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Procedure for Calling C Decode Functions

1. Append IE with value type ASN1T_HandoverType to list int Appendid_eNB_UE_S1AP_ID ASN1T_HandoverType value Get IE using id key value ASN1T_HandoverRequired_protocolIEs_element GetIE ASN1T_ProtocolIE_ID id Legacy Table Constraint Model The primary difference as to what a user sees and works with in the legacy model as opposed to the unions model lies in the representation of open type elements that contain a table constraint The standard form of an open type element constrained with a table constraint within a SEQUENCE container is as follows lt Type gt SEQUENCE lt element gt lt Class gt amp lt type field gt lt ObjectSet gt index element 87 Legacy Table Constraint Model If tables is not specified on the command line a standard open type structure is used to hold the element value typedef struct lt Type gt ASN10penType lt element gt The asn1openType built in type holds the element data in encoded form The only validation that is done on the element is to verify that it is a well formed tag length value TLV structure if BER encoding is used or a valid length prefixed structure for PER If the tables command line option is selected the code generated is different In this case ASN1OpenType above is replaced with asniobject Or ASN1TObject for C This is defined in asnitype h as follows typedef
2. General Status Messages Error Code Error Name Description 28 29 RTERR_FILNOTFOU RTERR_READERR File not found This status code is returned if an attempt is made to open a file input stream for decoding and the given file does not exist Read error This status code if returned if a read IO error is encountered when reading from an input stream associated with a physical device such as a file or socket 30 RTERR_WRITEERR Write error This status code if returned if a write IO error is encountered when attempting to out put data to an output stream associated with a physical device such as a file or socket 31 RTERR_INVBASE64 Invalid Base64 encoding This status code is re turned when an error is detected in decoding base64 data 32 33 RTERR_INVSOCKET RTERR_INVATTR Invalid socket This status code is returned when an attempt is made to read or write from a scoket and the given socket handle is invalid This may be the result of not having established a proper connection before trying to use the socket handle variable Invalid attribute This status code is returned by the decoder when an attribute is encountered in an XML instance that was not defined in the XML schema 34 RTERR_REGEXP Invalid regular expression This status code is re turned when a syntax error is detected in a regu lar expression value Details of the syntax error can be obtained
3. printf rtInitContext failed check license n rtErrPrint amp ctxt return stat pu_setBuffer amp ctxt msgbuf msglen aligned step 2 initialize the data variable asnlInit_PersonnelRecord amp employee step 3 call the decode function stat asnlPD_PersonnelRecord amp ctxt amp employee if stat 0 process received data else error processing rtxErrPrint amp ctxt step 4 free the context rtFreeContext amp ctxt An input stream can be used instead of a memory buffer as the data source by replacing the pu_setBuffer call above with one of the rtxStream CreateReader functions to set up a file mem ory or socket stream as input Procedure for Using the C Control Class De code Method The following are the steps are involved in decoding a PER message using the generated C class 1 Instantiate an ASN 1 PER decode buffer object ASN PERDecodeBuffer to describe the mes sage to be decoded The constructor takes as arguments a pointer to the message to be decoded the length of the message and a flag indicating whether aligned encoding was used or not 2 Instantiate an ASN1IT_ lt ProdName gt object to hold the decoded message data 3 Instantiate an ASN1IC_ lt ProdName gt object to decode the message This class associates the message buffer object with the object that is to receive the decoded data The results of the dec
4. CHOICE Value The mapping of an ASN 1 CHOICE value declaration to a global C or C value declaration is as follows ASN 1 production lt name gt lt ChoiceType gt lt value gt Generated code lt ChoiceType gt lt name gt The choice value will be initialized in the value initialization function For example consider the following declaration ChoiceType CHOICE oid OBJECT IDENTIFIER id INTEGER 80 Table Constraint Related Structures value ChoiceType id 1 This would result in the following definition in the C or C source file ChoiceType value Code generated in the value initialization function would be as follows value t T_ChoiceType_id value u id 1 Table Constraint Related Structures The following sections describe changes to generated code that occur when the tables or ta ble unions option is specified on the command line or when Table Constraint Options are selected from the GUI This option causes additional code to be generated for items required to support table constraints as specified in the X 682 standard This includes the generation of structures and classes for Information Object Classes Information Objects and Information Object Sets as spec ified in the X 681 standard Most of the additional items that are generated are read only tables for use by the run time for data validation purposes However generated structu
5. perform operations on decoded structure reset memory stat rtxMemReset amp ctxt More details may be found in the sample programs included in the ASNIC software development kit Two Phase Messaging MDER is specified using ITU T X 208 which uses a two phase method for encoding and decod ing ANY DEFINED By types These types are used to allow flexibility in message transmission by specifying a hole in a message to be filled in by a type specified by an object identifier Let us assume for sake of example that we wish to transmit a message that has a generic header and a payload defined by some object identifier We must first encode the payload and attach it to the message Then we can encode the whole message and transmit it Because this takes two steps we call this two phase encoding The inverse holds for decoding The whole message is first decoded The payload may then be identified and decoded according to its specific type This section describes how to perform two phase encoding and decoding using the MDER Run Time Library Examples are also provided in the distribution Two phase Encoding We demonstrate an example of two phase encoding using communication with an electrocardio gram This code is based on the ASN 1 specification provided in IEEE 11073 20601 2008 and submitted drafts for an application of this type Two phase encoding requires the use of multiple encoding contexts to enc
6. C C header filename This is used to specify the name of a C C header file to be used to store generated defini 38 Compiler Configuration File Name Values Description tions for the module By default the header file name is set to the ASN 1 name of the module with h appended to the end lt alias ASN 1 to computer lan This item allows a name in the ASN 1 specifica asnlname name codename name gt guage name mapping tion being compiled to be mapped to an alternate name in the generated computer language files The primary use is to allow shorter names to be used in places where a combination of names may be very long In this release the only names that can be used in the alias statement are infor mation object set names Production Level These attributes can be applied at the production level by including them within a lt production gt Description This attribute identifies the production type to which this section applies It is required This is used to specify a specific C integer or character string type be used in place of the de fault definition generated by ASNIC In the case of integers ASNIC will normally try and use the smallest integer type available based on the value or value range constraint on the integer type If the integer is not constrained the int32 32 bit integer type will be used For character string ASNIC will use a character
7. 117 Generated C C files and the compat Option These contain the functions to decode Name and encode Name respectively The ASN T_Name cpp file contains the type class methods and the ASN C_Name cpp files contains the control class methods Note that not all productions have a control class only PDU types do for BER or PER therefore the ASN C_ lt type gt cpp file may not be generated Similar files would be generated for the other productions in the module as well Note that for C the code reduction effect is less than that for pure C This is because most of the linkers cannot omit virtual methods even if they are not being used by the application These virtual methods refer to separate C functions and these functions are being linked into the application even if they are not actually used But still the size of the final application created with maxcfiles option should be less than the size of the application created without this option Generated C C files and the compat Option ASNIC 5 6 and below did not generate separate files for common definitions encode and de code functions lt moduleName gt c cpp lt moduleName gt Enc c cpp lt moduleName gt Dec c cpp All code was generated in a single file with the name lt moduleName gt c cpp If it is necessary to maintain this behavior then use the compat 5 6 option Also the behavior of the cfile option is slightly changed in ASNIC 5 7 and above In 5 6 a
8. In this definition lt object gt is an instance of the control class i e ASN1C_ lt prodName gt generated for the given production The lt outputStream gt placeholder represents an output stream object type This is an object derived from an ASN EncodeStream class The function result variable stat returns the completion status Error status codes are negative Return status values are defined in the rtxErrCodes h include file Another way to encode a message using the C classes is to use the lt lt streaming operator lt outputStream gt lt lt lt object gt Exceptions are not used in ASNIC C therefore the user must fetch the status value follow ing a call such as this in order to determine if it was successful The getStatus method in the ASN1EncodeStream class is used for this purpose Also the method Encode without parameters is supported for backward compatibility In this case it is necessary to create control class 1 e ASN1C_ lt prodName gt using an output stream reference as the first parameter and msgdata reference as the second parameter of the constructor Procedure for Using the Streaming C Control Class Encode Method The procedure to encode a message directly to an output stream using the C class interface is as follows 1 Create an OSRTOutputStream object for the type of output stream Choices are OSRTFileOut putStream for a file OSRTMemoryOutputStream for a memory buffer or OSRTSocketO
9. Populating Linked List Structures Populating generated list based SEQUENCE OF structures for the most part requires the use of dynamic memory to allocate elements to be added to the list note that it is possible to use static elements for this but this is unusual The recommended method is to use the built in run time memory management facilities available within the ASNIC runtime library This allows all list memory to be freed with one call after encoding is complete In the case of C the rtxMemAlloc or rtxMemAllocType function would first be used to allocate a record of the element type This element would then be initialized and populated with data The rtxDListAppend function would then be called to append it to the given list For C the compiler generates the helper methods NewElement and Append in the generated control class for a SEQUENCE OF type An instance of this class can be created using the list element within a generated structure as a parameter The helper methods can then be used to allocate and initialize an element and then append it to the list after it is populated See the cpp sample_ber employee writer cpp file for an example of how these methods are used In this program the following logic is used to populate one of the elements in the children list for encoding ASN1T_ChildInformation pChildInfo ASN1C__SeqOfChildInformation listHelper encodeBuffer msgData children pChildiInfo listHelp
10. Print Format The prtfmt option can be used in conjunction with any of the genPrint options documented above to alter the format of the printed data There are two possible print formats details and bracetext 243 Generated Compare Functions The details format prints a line by line display of every item in the generated structure For exam ple the following is an excerpt from a details display Employee name givenName John Employee name initial P Employee name familyName Smith Employee number 51 Employee title Director The alternative format bracetext provides a C like structure printout This is a more concise format that will omit optional fields that are not present in the decoded data An example of this is as follows Employee name givenName John initial P familyName Smith number 51 title Director As of ASNIC version 6 0 and higher bracetext is the default format used if prtfmt is not specified on the commandline Previous versions of ASN1C had details as the default setting Generated Compare Functions The genCompare option causes comparison functions to be generated These functions can be used to compare the contents of two generated type variables If an output file is not specified with the genCompare qualifier the functions are written to separate c files for each module in the source file The format of the name of each file is lt m
11. Procedure for Using the C Control Class Encode Method The procedure to encode a message using the C class interface is as follows 1 Create a variable of the ASN1T_ lt name gt type and populate it with the data to be encoded 2 Create an ASN BEREncode Buffer object 3 Create a variable of the generated ASN1C_ lt name gt class specifying the items created in 1 and 2 as arguments to the constructor 154 Generated C Encode Method Format and Calling Parameters 4 Invoke the Encode method The constructor of the ASN1C_ lt type gt class takes a message buffer object argument This makes it possible to specify a static encode message buffer when the class variable is declared A static buffer can improve encoding performance greatly as it relieves the internal software from having to repeatedly resize the buffer to hold the encoded message If you know the general size of the messages you will be sending or have a fixed size maximum message length then a static buffer should be used The message buffer argument can also be used to specify the start address and length of a received message to be decoded After the data to be encoded is set the Encode method is called This method returns the length of the encoded message or a negative value indicating that an error occurred The error codes can be found in the asn type h run time header file or in Appendix A of the C C Common Functions Reference Manual If encoding is
12. bs set 0 In this example lt seqVar gt would represent a generated SEQUENCE variable type and lt element gt would represent a bit string element within this type See the section on the ASN CBitStr class in the ASNIC C C Common Run time User s Manual for details on all of the methods available in this class 49 OCTET STRING OCTET STRING The ASN 1 OCTET STRING type is converted into a C structured type containing an integer to hold the number of octets and an array of unsigned characters OCTETs to hold the octet string contents The number of octets integer specifies the actual number of octets in the contents field The allocation for the contents field depends on how the octet string is specified in the ASN 1 definition If a size constraint is used a static array of that size is generated otherwise a pointer variable is generated to hold a dynamically allocated string The decoder will automatically allocate memory to hold a parsed string based on the received length of the string For C constructors and assignment operators are generated to make assigning variables to the structures easier In addition to the default constructor a constructor is provided for string or binary data An assignment operator is generated for direct assignment of a null terminated string to the structure note this assignment operator copies the null terminator at the end of the string to the data Dynamic OCTET STRING ASN 1
13. define NamedBS_bitTen 10 define SET_BS3_ bitTen bs lt code to set bit gt define CLEAR _BS3_bitTen bs lt code to clear bit gt define TEST_BS3_bitTen bs lt code to test bit gt Type definitions typedef struct ASN1T_NamedBS OSUINT32 numbits OSOCTET data 2 NamedBS The named bit constants would be used to access the data array within the ASN T_NamedBS type If bit macros were not generated the rtxSerBit function could be used to set the named bit bitOne with the following code NamedBS bs memset amp bs 0 sizeof bs rtxSetBit bs data 10 NamedBS_bitOne The statement to clear the bit using rtxClearBit would be as follows rtxClearBit bs data 10 NamedBS_bitOne Finally the bit could be tested using rtxTestBit with the following statement if rtxTestBit bs data 10 NamedBS_bitOne 48 BIT STRING bit is set Note that the compiler generated a fixed length data array for this specification It did this because the maximum size of the string is known due to the named bits it must only be large enough to hold the maximum valued named bit constant Contents Constraint It is possible to specify a contents constraint on a BIT STRING type using the CONTAINING keyword This indicates that the encoded contents of the specified type should be packed within the BIT STRING container An example of this type of constraint is as follows
14. error processing decodeBuffer PrintErrorInfo O step 6 free dynamic memory object aligned object object r msgData will be done automatically when both the decodeBuffer and employ of scope objects go out A stream can be used as the data input source instead of amemory buffer by creating an OSRT input stream object in step and associating it with the decodeBuffer object For example to read from a file input stream the decodeBuffer declaration in step 1 would be replaced with the following two statements OSRTFileInputStream istrm filename 198 Decoding a Series of Messages Us ing the C Control Class Interface ASNIPERDecodeBuffer decodeBuffer istrm aligned Decoding a Series of Messages Using the C Control Class Interface The above example is fine as a sample for decoding a single message but what happens in the more typical scenario of having a long running loop that continuously decodes messages The logic shown above would not be optimal from a performance standpoint because of the constant creation and destruction of the message processing objects It would be much better to create all of the required objects outside of the loop and then reuse them to decode and process each message A code fragment showing a way to do this is as follows include employee h include file generat main OSOCTET msgbuf 1024 int msglen stat OSBOO
15. format 1 e without the braces But this should provide the general idea of how it is done 254 How to Use It Example 2 An Error Handler Despite the addition of things like extensibility and version brackets ASN 1 implementations get out of sync For situations such as this the user needs some way to intervene in the parsing process to set things straight This is faulttolerance the ability to recover from certain types of errors The error handler interface is provided for this purpose The concept is simple Instead of throwing an exception and immediately terminating the parsing process a user defined callback function is first invoked to allow the user to check the error If the user can fix the error all he or she needs to do is apply the appropriate patch and return a status of 0 The parser will be none the wiser It will continue on thinking everything is fine This interface is probably best suited for recovering from errors in BER or DER instead of PER The reason is the TLV format of BER makes it relatively easy to skip an element and continue on It is much more difficult to find these boundaries in PER Our example can be found in the cpp sample_ber errorHandler subdirectory In this example we have purposely added a bogus element to one of the constructs within an encoded employee record The error handler will be invoked when this element is encountered Our recovery action will simply be to print out a wa
16. stat rtInitContext amp ctxt if stat 0 printf rtInitContext failed check license n rtxErrPrint amp ctxt return stat Create memory output stream stat rtxStreamMemoryCreateWriter amp ctxt 0 0 if stat lt 0 printf Create memory output stream failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat Encode stat OEREnc_PersonnelRecord amp ctxt amp employee msgptr rtxStreamMemoryGetBuffer amp ctxt amp len if trace printf Hex dump of encoded record n rtxHexDump msgptr len In general static buffers should be used for encoding messages where possible as they offer a substantial performance benefit over dynamic buffer allocation The problem with static buffers however is that you are required to estimate in advance the approximate size of the messages you will be encoding There is no built in formula to do this the size of an ASN 1 message can vary widely based on data types and other factors The use of streams is a good alternative for large messages as the entire encoded message does not need to fit into memory 203 Generated OER Decode Functions Generated OER Decode Functions OER encode decode functions are generated when the oer switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C OER decode function is generated T
17. A decode function can then be called to decode the message If the return status indicates success 0 then the message will have been decoded into the given ASN 1 type variable The decode function may automatically allocate dynamic memory to hold variable length variables during the course of decoding This memory will be tracked in the context structure so the programmer does not need to worry about freeing it It will be released when the context is freed The final step of the procedure is to free the context block The function to free the context is rtFreeContext A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main PersonnelRecord data OSCTXT ctxt OSBOOL trace TRUE verbose FALSE const char filename message xml int i stat logic to read message into msgbuf This example uses a static context block step 1 initialize the context block stat rtXmlInitContext amp ctxt if stat 0 rtxErrPrint amp ctxt return stat step 2 open an input stream stat rtxStreamFileCreateReader amp ctxt filename if stat 0 rtxErrPrint amp ctxt return 1 step 3 attempt to match the start tag to a known value if 0 rtXmlpMatchStartTag amp ctxt OSUTF8 Employee Note that it is necessary to mark the last event active in the pull pars
18. ContainingBS BIT STRING CONTAINING INTEGER ASNIC will generate a type definition that references the type that is within the containing con straint In this case that would be INTEGER therefore the generated type definition would be as follows typedef OSINT32 ContainingBS The generated encoders and decoders would handle the extra packing and unpacking required to get this to and from a BIT STRING container This direct use of the containing type can be suppressed through the use of the noContaining command line argument In this case a normal BIT STRING type will be used and it will be the users responsibility to do the necessary packing and unpacking operations to encode and decode the variable correctly ASN1CBitStr Control Class When C code generation is specified a control class is generated for operating on the target bit string This class is derived from the ASN1CBitStr class This class contains methods for operating on bits within the string Objects of this class can also be declared inline to make operating on bits within other ASN 1 constructs easier For example ina SEQUENCE containing a bit string element the generated type will contain a public member variable containing the ASNIT type that holds the message data If one wanted to operate on the bit string contained within that element they could do so by using the ASN1CBitStr class inline as follows ASNICBitStr bs lt seqVar gt lt element gt
19. Control Class Encode Method 4 Invoke the ASN1C_ lt ProdName gt object Encode method 5 Check the return status The return value is a status value indicating whether encoding was successful or not Zero indicates success If encoding failed the status value will be a negative number The encode buffer method printErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred 6 If encoding was successful get the start of message pointer and message length The start of message pointer is obtained by calling the getMsgPtr method of the encode buffer object If static encoding was specified i e a message buffer address and size were specified to the PER Encode Buffer class constructor the start of message pointer is the buffer start address The message length is obtained by calling the getMsgLen method of the encode buffer object A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC main const OSOCTET msgptr OSOCTET msgbuf 1024 int msglen stat OSBOOL aligned TRUE step 1 instantiate an instance of the PER encod buffer class This example specifies a static message buffer ASNIPEREncodeBuffer encodeBuffer msgbuf sizeof msgbuf aligned step 2 populate msgData with data to be encoded ASN1T_PersonnelRecord msgData msgData
20. OSCTXT pctxt In this definition lt testFunc gt denotes the formatted function name defined above The pct xt argument is used to hold a context pointer to keep track of dynamic memory allocation parameters This is a basic handle variable that is used to make the function reentrant so that it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable must have been previously initialized using the rt nitContext run time function The pvalue argument is a pointer to hold the populated data variable This variable is of the type generated for the ASN 1 production The test function will automatically allocate dynamic memory using the run time memory management for the main variable as well as variable length fields within the structure This memory is tracked within the context structure and is released when the context structure is freed In the case of C a method is added to the generated control class for test code generation The name of this method is genTestInstance The prototype is as follows lt typeName gt pvalue lt object gt genTestInstance j where lt typeName gt is the ASN1T_ lt name gt type name of the generated type and lt object gt is an instance of the ASN1IC_ lt name gt generated control class 248 Generated Test Functions Generated DOM Test Functions A new command line
21. The difference between the two types is the C version contains constructors to initialize the value to zero or to a given open type value If the tables command line option is selected and the ASN 1 type definition references a table constraint the code generated is different In this case ASN OpenType above is replaced with ASN1 Object or ASNITObject for C This is defined in asn type h as follows typedef struct generic table constraint value holder ASN10OpenType encoded void decoded 69 Character String Types OSINT32 index table index ASN1Object This allows a value of any ASN 1 type to be represented in both encoded and decoded forms Encoded form is the open type form shown above It is simply a pointer to a byte buffer and a count of the number of byes in the encoded message component The decoded form is a pointer to a variable of a specific type The pointer is void because there could be a potentially large number of different types that can be represented in the table constraint used to constrain a type field to a given set of values The index member of the type is for internal use by table constraint processing functions to keep track of which row in a table is being referenced If the table unions command line option is used a more specialized type of structure is generated In this case instead of a void pointer being used to hold an instance of a type containing data to be encoded all
22. The type for the protocol IE list element is created in much the same way as the main message type was above typedef struct HandoverRequired_protocollIEs_element ProtocolIE_ID id Criticality criticality struct information object selector x7 HandoverRequiredIEs_TVALUE t HandoverRequiredIEs information objects union id id MME UE S1AP ID criticality reject presence mandatory if MME_UE_S1AP_ID _HandoverRequiredIEs_id_MME_UE_S1AP_ID id id HandoverType criticality reject presence mandatory 7 HandoverType _HandoverRequiredIEs_id_HandoverType x id id Cause criticality ignore presence mandatory a u value HandoverRequired_protocollEs_element In this case the protocol IE id field and criticality are generated as usual using the fixed type field type definitions The open type field once again results in the generation of a union structure of all possible type fields that can be used Note in this case the field names are automatically generated _HandoverRequiredIEs_id_ MME_UE_S1AP_ID etc The reason for this was the use of inline information object definitions in the information object set as opposed to defined object definitions This is a sample from that set HandoverRequiredIEs S1AP PROTOCOL IES ID id MME UE S1AP ID CRITICALITY reject TYP ID id HandoverType CRITICALITY rej
23. end of loop BER Decode Performance Enhance ment Techniques There are a number of different things that can be done in application code to improve BER decode performance These include adjusting memory allocation parameters using compact code genera tion using decode fast copy and using initialization functions Dynamic Memory Management By far the biggest performance bottleneck when decoding ASN 1 messages is the allocation of memory from the heap Each call to new or malloc is very expensive 173 Compact Code Generation The decoding functions must allocate memory because the sizes of many of the variables that make up a message are not known at compile time For example an OCTET STRING that does not contain a size constraint can be an indeterminate number of bytes in length ASNIC does two things by default to reduce dynamic memory allocations and improve decoding performance 1 Uses static variables wherever it can Any BIT STRING OCTET STRING character string or SEQUENCE OF or SET OF construct that contains a size constraint will result in the generation of a static array of elements sized to the max constraint bound 2 Uses a special nibble allocation algorithm for allocating dynamic memory This algorithm al locates memory in large blocks and then splits up these blocks on subsequent memory alloca tion requests This results in fewer calls to the kernel to get memory The downside is that one request for
24. pvalue For a Type Field definition a virtual method is added for each encoding rules type to call the generated C encode and decode functions If print is specified a print method is also generated virtual int encode lt ER gt lt FieldName gt OSCTXT pctxt ASN1TObject amp object return 0 virtual int decode lt ER gt lt FieldName gt OSCTXT pctxt ASN1TObject amp object return 0 virtual void print lt FieldName gt ASN1ConstCharPtr name ASN1TObject amp object For an Object Field class lt ClassName gt lt FieldName gt In each of these definitions lt FieldName gt would be replaced with the name of the field without the leading amp lt TypeName gt would be replaced with the C type name for the ASN 1 Type lt ClassName gt would be replaced with the C type name of the class for the Information Object lt ER gt would be replaced by an encoding rules type BER PER or XER As an example consider the following ASN 1 class definition ATTRIBUTE CLASS amp Type amp ParameterType OPTIONAL amp id OBJECT IDENTIFIER UNIQUE WITH SYNTAX amp Type ID amp id This would result in the following definition in the C source file class EXTERN ATTRIBUTE protected ASN1TObjId id 90 Legacy Table Constraint Model ATTRIBUTE public virtual int encodeBERType OSCTXT pctxt ASN1ITO
25. ssseeseeesesseeeeseesresressersresrerstesesrrssreseeseresressesee 30 Porting Run time Code to Other Platforms eeseseeseeeeseseeeseserssrseresresseseresresseseresresserseesees 32 Compiler C nfig ration File sienien a A E e E E E ASi 33 Compil r Error Reportin oeren ea a E Reels Pa iia A eal Indi lea aes aek 41 ASN T TO C C Map pin csi a ea Mere nai A aa E Goa te A A a EE E EES 43 Type Mappini os a a ce as Bee E E a E RE 43 SCOTS AIN N E A A E E A 43 INTEGER terori nTa R E e EE E E dm alas 43 BEF STRING erie saa a a E E ASN 45 OCTETS DRING masarni re eTe See io eee ae a eee 50 ENUMERA TED 0 a cog a ath hg Gacraan saan chide A anders ep eee oe gee tecietss 51 NULE ccs tee ca Pa tg Aas ie RO A a IE a Sl AA TE 53 OBJECT IDENTIFIER A aest oe ee a e tan sth Sas EO i 53 REALE FID ate Sue acc a e a Es ea e 54 REAT ea teks eg eh aoa a eee ae ae 54 SEQUENCE acs area ci ce SN alah eee Neal nt a eae E SNe aD Ae Da 55 SET oian a a E a R N ete ones 60 SEQUENCE OF ia hose A e outa S E EAEE E E 61 SARO E A E E E E A 65 CHOICES ton ar a ad he cleat ha esata dogg eat a aa 65 Open Type stir seen a A A aaah tod E agak mania 69 Character Strine TYPES aiie no TEE cea E Cat oS E T RL a 70 Time String Types ereis ieee tet E R T a N 71 EXTERNA Tosan t R a aE TEE ea ae A 12 EMBEDDED PDV ieena o a e r A AE E E ane E ET 12 Parameterized Types n Inn u a E Gul is yada eg see nae ale sa e 13 Value Mappings 4c cS ite eee Mie tat aie ee oe ieee eee 75 BOOLEAN V
26. BIT STRING can also be used as the type in this type of declaration ASN 1 production lt name gt OCTET STRING lt bstring gt B Generated code OSUINT32 lt name gt _numocts lt length gt OSOCTET lt name gt _data lt data gt A hexadecimal string would be the same except the ASN 1 constant would end in a H Character String Value A character string declaration would cause a C or C const char declaration to be generated ASN 1 production lt name gt lt string type gt lt value gt Generated code T11 Object Identifier Value Specification const char lt name gt lt value gt In this definition lt string type gt could be any of the standard 8 bit characters string types such as TA5String PrintableString etc Note Code generation is not currently supported for value declarations of larger character string types such as BMPString Object Identifier Value Specification Object identifier values result in a structure being populated in the C or C source file ASN 1 production lt name gt OBJECT IDENTIFIER lt value gt Generated code ASN1OBJID lt name gt lt value gt For example consider the following declaration oid OBJECT IDENTIFIER ccitt b 5 10 This would result in the following definition in the C or C source file ASNLOBJID oid 35 f Oy by L0 bi To populate a variable in
27. This option instructs the compiler not to au tomatically generate unique names to resolve 15 Running ASNIC from the Command line Option Argument Description name collisions in the generated code Name collisions can occur for example if two mod ules are being compiled that contain a produc tion with the same name A unique name is gen erated by prepending the module name to one of the productions to form a name of the form lt module gt _ lt name gt Note that name collisions can also be manual ly resolved by using the typePrefix enumPre fix and valuePrefix configuration items see the Compiler Configuration File section for more details Previous versions of the compiler did not gener ate unique names by default The compiler op tion uniquenames has been deprecated in favor of nouniquenames lt directory gt This option is used to specify the name of a di rectory to which all of the generated files will be written objdir lt directory gt This option is used in conjunction with the gen Make option to specify the name of the object file directory to be added to the makefile Com piled object files will be output to this directory oh lt directory gt This option is used to specify the name of a di rectory to which only the generated header files h will be written oer None This option instructs the compiler to gener ate functions that imp
28. and the Ext specification contains the extension enumerated items The form of the typedef following the struct specification depends on whether or not the enumerated type contains an extension marker or not If a marker is present it means the type can contain values outside the root enumeration An OSUINT32 is always used in the final typedef to ensure a consistent size of an enumerated variable and to handle the case of unknown extension values NULL The ASN 1 NULL type does not generate an associated C or C type definition OBJECT IDENTIFIER The ASN 1 OBJECT IDENTIFIER type is converted into a C or C structured type to hold the subidentifier values that make up the object identifier ASN 1 production lt name gt OBJECT IDENTIFIER Generated C code typedef ASN1OBJID lt name gt Generated C code typedef ASN1TObjId ASN1T_ lt name gt In this case different base types are used for C and C The difference between the two is the C version includes constructors and assignment operators that make setting the value a bit easier 53 RELATIVE OID The ASN OBJID type i e the type used in the C mapping is defined in asnI type h to be the following typedef struct OSUINT32 numids number of subidentifiers OSUINT32 subid ASN_K_MAXSUBIDS subidentifier values ASN1OBJID The constant ASN_K_MAXSUBIDS specifies the maximum number of sub identifiers that can be
29. be resolved 278 ASN 1 specific Status Messages Error Code Error Name Description ASN_E_BASE 10 ASN_E_INVPERENC Invalid PER encoding This occurs when a given element within an ASN 1 specification is con figured to have an expected PER encoding and the decoded value does not match this encoding 279 280
30. gnu files in the root directory of the installation are sample files for Windows 32 Visual C and GNU compilers respectively Either of these can be renamed to platform mk for building in either of these environments 6 Invoke the makefile in the build_lib subdirectory If all parameters were set up correctly the result should be binary library files created in the lib subdirectory Compiler Configuration File In addition to command line options a configuration file can be used to specify compiler options These options can be applied not only globally but also to specific modules and productions A simple form of XML is used to format items in the file XML was chosen because it is fairly well known and provides a natural interface for representing hierarchical data such as the structure of ASN 1 modules and productions The use of an external configuration file was chosen over embedding directives within the ASN 1 source itself due to the fact that ASN 1 source versions tend to change frequently An external configuration file can be reused with a new version of an ASN 1 module but internal directives would have to be reapplied to the new version of the ASN 1 code At the outer level of the markup is the lt asniconfig gt lt asniconfig gt tag pair Within this tag pair the specification of global items and modules can be made Global items are applied to all items in all modules An example would be the lt storage gt qualifier A
31. structures at different levels within other nested ASN 1 structures SEQUENCEs SETs or other CHOICEs A problem arises when CHOICE element names at different levels are not unique this is likely when elements are unnamed The problem is that generated tag constants are not guaran teed to be unique since only the production and end element names are used The compiler gets around this problem by checking for duplicates If the generated name is not unique a sequential number is appended to make it unique The compiler outputs an informational message when it does this An example of this can be found in the following production C CHOICE 0 INTEGER 1 CHOICE 0 INTEGER 1 BOOLEAN This will produce the following C code define T_C_alInt define T_C_aChoice define T_C_alInt_1l define T_C_aBool NRNEHE typedef struct ant ce union OSINT32 alInt struct 67 CHOICE intti union OSINT32 alInt OSBOOL aBool u aChoice C Note that _1 was appended to the second instance of T_c_arnt Developers must take care to ensure they are using the correct tag constant value when this happens Populating Generated Choice Structures Populating generated CHOICE structures is more complex then for other generated types due to the use of pointers within the union construct As previously mentioned the use of pointers with C can be prevented by using the
32. typedef OSBOOL lt name gt Generated C code typedef OSBOOL ASN1T_ lt name gt For example if B PRIVATE 10 BOOLEAN was defined as an ASN 1 production the generated C type definition would be typedef ossooL B Note that the tag information is not represented in the type definition It is handled within the generated encode decode functions The only difference between the C and C mapping is the addition of the asnit_ prefix on the C type INTEGER The ASN 1 INTEGER type is converted into one of several different C types depending on con straints specified on the type By default an INTEGER with no constraints results in the generation of an OSINT32 type In the global include file osSysTypes h os1nT32 is defined to be an int which is normally a signed 32 bit integer value on most computer systems ASN 1 production lt name gt INTEGER Generated C code typedef OSINT32 lt name gt Generated C code typedef OSINT32 ASN1T_ lt name gt 43 INTEGER Value range constraints can be used to alter the C type used to represent a given integer value For example the following declaration from the SNMP SMI specification would cause an OSUINT32 type mapped to a C unsigned int to be used Counter APPLICATION 1 IMPLICIT INTEGER 0 4294967295 In this case an os1nT32 could not be used because all values within the given range could not be represented Other value rang
33. 1 name id subid 2 1 C Code Generation The C classes generated for ASN 1 information objects are derived from the ASN 1 class objects The constructors in these classes populate the fixed type field member variables with the values specified in the information object The classes also implement the virtual methods generated for the information object type fields All non optional methods are required to be implemented The optional methods are only implemented if they are defined in the information object definition An example of an information object definition that is derived from the ASN 1 class above is as follows name ATTRIBUTE WITH SYNTAX VisibleString ID Qh OL ab A This results in the generation of the following C class class EXTERN name public ATTRIBUTE public name virtual int encodeBERType OSCTXT pctxt ASN1TObject amp object virtual int decodeBERType OSCTXT pctxt ASN1TObject amp object bi The constructor implementation for this class not shown sets the fixed type fields ia to the assigned values 0 1 1 The class also implements the virtual methods for the type field virtual 94 Legacy Table Constraint Model methods defined in the base class These methods simply call the BER encode or decode method for the assigned type this example assumes ber was specified for code generation other encode rules could have been used
34. 1 SEQUENCE definition the lt element name gt tokens at the beginning of element dec larations are optional It is possible to include only a type name without a field identifier to define an element This is normally done with defined type elements but can be done with built in types as well An example of a SEQUENCE with unnamed elements would be as follows AnInt PRIVATE 1 INTEGER Aseq PRIVATE 2 SEQUENCE x INTEGER AntInt In this case the first element x is named and the second element is unnamed ASNI1C handles this by generating an element name using the type name with the first character set to lower case For built in types a constant element name is used for each type for example alnt is used for INTEGER There is one caveat however ASNIC cannot handle multiple unnamed elements in a SEQUENCE or SET with the same type names Element names must be used in this case to distinguish the elements So for the example above the generated code would be as follows typedef OSINT32 AnInt 57 SEQUENCE typedef struct Aseq OSINT32 x AnInt anInt Aseq OPTIONAL keyword Elements within a sequence can be declared to be optional using the OPTIONAL keyword This indicates that the element is not required in the encoded message An additional construct is added to the generated code to indicate whether an optional element is present in the message or
35. 1s We 108 Substitution Groups typedef struct EXTERN MyBaseElement_group int ty union t 1 MyBaseElement myBaseElement t 2 MyExtendedElement myExtendedElement u MyBaseElement_group typedef struct EXTERN MyType MyBaseElement_group myBaseElement MyType typedef MyType MyElement In this case if myElement Or MyType is used it can be populated with either base element or extended element data 109 110 Generated C C Source Code Header h File The generated C or C include file contains a section for each ASN 1 production defined in the ASN 1 source file Different items will be generated depending on whether the selected output code is C or C In general C will add some additional items such as a control class definition onto what is generated for C The following items are generated for each ASN 1 production e Tag value constant e Choice tag constants CHOICE type only e Named bit number constants BIT STRING type only e Enumerated type option values ENUMERATED or INTEGER type only e C type definition e Encode function prototype e Decode function prototype e Other function prototypes depending on selected options for example print e C control class definition C only A sample section from a C header file is as follows J Kk kk ko he A EmployeeNumber E E A
36. Before any encode function can be called the user must first initialize an encoding context This is a variable of type OSCTXT This variable holds all of the working data used during the encod ing of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished by using the mderInitContext function as follows OSCTXT ctxt if mderInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 After initializing the context and populating a variable of the structure to be encoded an encode function can be called to encode the message A program fragment that could be used to encode a simple release request PDU is as follows include IEEE 11073 20601 ASN1 h include file generated by ASNIC int main void ApduType data typedef generated by ASNIC OSCTXT ctxt OSOCTET msgptr int stat Step 1 Initialize the context and set the buffer pointer stat mderInitContext amp ctxt if stat 0 initialization failed could be a license problem rtxErrPrint amp ctxt return stat Step 2 Populate the structure to b ncoded asnlInit_ApduType amp data data t T_ApduType_rirq data u rlrq rtxMemAllocTypeZ amp ctxt
37. C TYPE MAPPINGS ASNIC can accept as input XML schema definition XSD specifications in addition to ASN 1 specifications If an XSD specification is compiled the compiler does internal translations of the XSD types into equivalent ASN 1 types as specified in ITU T standard X 694 The following sec tions provide information on the translations and the C C type definitions generated for the dif ferent XSD types XSD Simple Types The translation of XSD simple types into ASN 1 types is straightforward in most cases a one to one mapping from XSD simple type to ASN 1 primitive type exists The following table sum marizes these mappings XSD Simple Type ASN 1 Type anyURI UTF8String base64Binary OCTET STRING boolean BOOLEAN byte INTEGER 128 127 date UTF8String datetime UTF8String decimal UTF8String double REAL duration UTF8String ENTITIES SEQUENCE OF UTF8String ENTITY UTF8String float REAL gDay UTF8String gMonth UTF8String gMonthDay UTF8String gYear UTF8String gYearMonth UTF8String hexBinary OCTET STRING ID UTF8String IDREF UTF8String IDREFS SEQUENCE OF UTF8String integer INTEGER 97 XSD Complex Types XSD Simple Type ASN 1 Type int INTEGER 2147483648 2147483647 language UTF8String long INTEGER 9223372036854775808 9223372036854775807 Name UTF8String NCName UTF8String ne
38. C C null terminated character string types The C version of the product contains additional control classes for parsing and formatting time string values When C code generation is specified a control class is generated for operating on the target time string This class is derived from the ASNI CGeneralizedTime or ASN CUTCTime 71 EXTERNAL class for GeneralizedTime or UTCTime respectively These classes contain methods for formatting or parsing time components such as month day year etc from the strings Objects of these classes can be declared inline to make the task of formatting or parsing time strings easier For example in a SEQUENCE containing a time string element the generated type will contain a public member variable containing the ASNIT type that holds the message data If one wanted to operate on the time string contained within that element they could do so by using one of the time string classes inline as follows ASN1CGeneralizedTime gtime msgbuf lt seqVar gt lt element gt gtime setMonth ASN1CTime November In this example lt seqvar gt would represent a generated SEQUENCE variable type and lt element gt would represent a time string element within this type See the ASN1CTime ASN1CGeneralizedTime and ASN1CUTCTime Subsections in the C C Run Time Library Reference Manual for details on all of the methods available in these classes EXTERNAL The ASN 1 EXTERNAL type is a useful t
39. Constraint It is possible to specify a contents constraint on an OCTET STRING type using the CONTAINING keyword This indicates that the encoded contents of the specified type should be packed within the OCTET STRING container An example of this type of constraint is as follows ContainingOS OCTET STRING CONTAINING INTEGER ASNIC will generate a type definition that references the type that is within the containing con straint In this case that would be INTEGER therefore the generated type definition would be as follows typedef OSINT32 ContainingOS The generated encoders and decoders would handle the extra packing and unpacking required to get this to and from an OCTET STRING container This direct use of the containing type can be suppressed through the use of the noContaining command line argument In this case a normal OCTET STRING type will be used and it will be the users responsibility to do the necessary packing and unpacking operations to encode and decode the variable correctly ENUMERATED The ASN 1 ENUMERATED type is converted into different types depending on whether C or C code is being generated The C mapping is either a C enum or integer type depending on whether or not the ASN 1 type is extensible or not The C mapping adds a struct wrapper around this type to provide a namespace to aid in making the enumerated values unique across all modules C Mapping 51 ENUMERATED ASN 1 p
40. DataProto pDataProto DataProto pnode gt data Create memory input stream stat rtxStreamMemoryCreateReader amp ctxt OSOCTET pDataProto gt data_proto_info data pDataProto gt data_proto_info numocts Note here that the rtxst reamMemoryCreateReader function is used to stream data from the previous ly decoded message It points to the octets held inside of the open type After initializing the stream reader the data can be decoded into the appropriate structure using the corresponding MDERDec function Decode PhdAssociationInformation asnlInit_PhdAssociationInformation amp phdAssocInfo stat MDERDec_PhdAssociationInformation amp ctxt amp phdAssocInfo if stat 0 215 Two phase Decoding printf decode of ApduType failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt return 1 rtxStreamClose amp ctxt pnode pnode gt next 216 Generated XML Functions Generated XER Encode Functions XER stands for XML Encoding Rules a form of XML specified in the X 693 standard for use with ASN 1 NOTE XER is maintained as a legacy XML format for ASN 1 New applications should consider using XML as described in the next section instead of XER XML is more closely aligned with W3C standard XML and XML schema XER C encode functions are generated when the xer switch is specified on the command line For each ASN 1 prouction defined in
41. Decod 0 decoding successful data in msgData process received data else error processing case TV_ handle other known messages Note that the call to free memory is not required to release dynamic memory when using the C interface This is because the control class hides all of the details of managing the context and releasing dynamic memory The memory is automatically released when both the message buffer object ASNIBERMessageBuffer and the control class object ASNIC_ lt ProdName gt are deleted or go out of scope Reference counting of a context variable shared by both interfaces is used to accomplish this Decoding a Series of Messages Using the C Control Class Interface The above example is fine as a sample for decoding a single message but what happens in the more typical scenario of having a long running loop that continuously decodes messages The logic shown above would not be optimal from a performance standpoint because of the constant creation and destruction of the message processing objects It would be much better to create all of the required objects outside of the loop and then reuse them to decode and process each message A code fragment showing a way to do this is as follows include employee h include file generated by ASNIC main OSOCTET msgbuf 1024 ASNITAG msgtag int msglen status Create message buffer ASNIT and ASNIC objects
42. Generated C Function Format and Calling Parameters ssssseesseeesseeessressersseessee 223 Procedure for Calling C Decode Functions s sssessesssesssesessseesseesseesseressreessresseesse 224 Procedure for Using the C Interface eeeeeseeseeeeesieesesresseseresresrereresresseserssresse 226 Procedure for Interfacing with Other C and C X ML Parser Libraries 227 Generated XML Encode Functions sssesseeseeeeesesesesressessrssresseserssressesnrestessetseesrenseeseeseessee 227 Generated C Function Format and Calling Parameters sssesessseeeseseessressesssessseee 229 Procedure for Calling C Encode Functions oo cee ceeeeseesseceseeeeeeeeseecsaeenseeseeeeenees 230 Generated C Encode Method Format and Calling Parameters 0 0 eee 231 Procedure for Using the C Control Class Encode Method eeeeeeeeeeeees 231 Generated XML Decode Functions 2i 2 i0sccnii ddan pied lddaneanladinue 233 Generated C Function Format and Calling Parameters ceesceeeseceeeseeeenteeees 233 Procedure for Calling C Decode Functions 00 0 cece eeeceeseeeenceceseceeeeeeeeeeneeeaeenes 234 Generated C Decode Method Format and Calling Parameters eee 236 Procedure for Using the C Control Class Decode Method sosesc 236 Additional Generated Functions ss vce2ttidecstis decal seeertea ected Hedileee hee eahesteetedenlees 239 Generated Initialization Functions 0 0 0 eeeeseesseceseceseeesscecaeceseessneeeaeecsaecaeesseeesaeess
43. OBJECT IDENTIFIER UNIQUE WITH SYNTAX amp Type ID amp id This would result in the following definition in the C source file typedef struct ATTRIBUTE int TypeSize int encodeType OSCTXT void ASN1TagType int decodeType OSCTXT void ASN1ITagType int ASNI1OBJID id C Code generation The C abstract class generated to model an ASN 1 CLASS contains member variables for each of the fields within the class Derived information object classes are required to populate these variables with the values defined in the ASN 1 information object specification The C class also 89 Legacy Table Constraint Model contains virtual methods representing each of the type fields within the ASN 1 class specification If the field is not defined to be OPTIONAL in the ASN 1 specification then it is declared to be abstract in the generated class definition A class generated for an ASN 1 information object that references this base class is required to implement these abstract virtual methods For each of the following CLASS fields a corresponding member variable is generated in the C class definition as follows For a Value Field definition the following member variable will be added Also an Equals method will be added if required for table constraint processing lt TypeName gt lt FieldName gt inline OSBOOL idEquals lt TypeName gt
44. OK status indicating encoding was successful A negative value indicates encoding failed Return status val ues are defined in the asnItype h include file The error text and a stack trace can be displayed using the rtxErrPrint function Populating Generated Structure Variables for Encoding See the section Populating Generated Structure Variables for Encoding for a discussion on how to populate variables for encoding There is no difference in how it is done for BER versus how it is done for OER Procedure for Calling C Encode Functions This section describes the step by step procedure for calling a C OER encode function This method must be used if C code generation was done Before an OER encode function can be called the user must first initialize an encoding context block structure The context block is initialized by calling the rt nitContext function The user then has the option to do stream based or memory based encoding If stream based is to be done the user must call a rtxStreamCreate Writer function for the type of stream to which data will be written For example if the user wishes to write data to a file the rtxStreamFileCreate Writer function would be called To do memory based encoding the rtx nitContextBuffer function would be called This can be used to specify use of a static or dynamic memory buffer Specification of a dynamic buffer is possible by setting the buffer address argument to null and the buffer size ar
45. PROTOCOL IES amp Value IEsSetParam id In this case 1EsSetParam refers to an information object set specification that constrains the values that are allowed to be passed for any given instance of a type referencing a ProtocolIE Field The compiler does not add any extra code to check for these values so the parameter can be discarded note that this is not true if the tables compiler option is specified After processing the Infor mation Object Class references within the construct refer to the section on Information Objects 74 Value Mappings for information on how this is done the reduced definition for ProtocolIE Field becomes the following ProtocolIE Field SEQUENCE id ProtocolIE ID criticality Criticality value ASN 1 OPEN TYPE References to the field are simply replaced with a reference to the protocolID Fiela typedef If tables is specified the parameters are used and a new type instance is created in accordance with the rules above Value Mappings ASNIC can parse any type of ASN 1 value specification but it will only generate code for follow ing value specifications e BOOLEAN e INTEGER e REAL e ENUMERATED e Binary String e Hexadecimal String e Character String e OBJECT IDENTIFER All value types except INTEGER and REAL cause an extern statement to be generated in the header file and a global value assignment to be added
46. Reserved Usage asnlc lt filename gt lt options gt lt filename gt ASN 1 or XSD source filename s Multiple filenames may be specified and wildcards are allowed language options g generate C cod c generate C code c generate C code java generate Java code cldc generate Java ME CLDC compatible code xsd lt filename gt generate XML schema definitions encoding rule options ber generate BER encode decode functions cer generate CER encode decode functions der generate DER encode decode functions oer generate OER encode decode functions mder generate MDER encode decode functions per generate PER encode decode functions xer generate XER encode decode functions xml generate XML encode decode functions basic options asnl lt file gt generate pretty printed ASN 1 source code asnstd lt std gt set standard to be used for parsing ASN 1 source file Possible values x208 x680 mixed default is x680 compact generate compact code compat lt version gt generate code compatible with previous compiler version lt version gt format is x x for example 5 3 Running ASNIC from the Command line config lt file gt specify configuration file depends compile main file and dependent IMPORT items html generate HTML marked up version of ASN 1 I lt directory gt set import file directory lax do not generate co
47. SYNTAX amp Type IDENTIFIED BY amp id HAS PROPERTY amp property The ASNIC compiler generates code for these constructs when they are referenced in the ASN 1 source file that is being compiled The generated code for these constructs is written to the RtClass h and c cpp source files Information Object Information Object code will be generated in a header and source file with a C struct C class to hold the values The name of the header and source file are of the following format lt ModuleName gt Table h lt ModuleName gt Table c cpp In this definition lt ModuleName gt would be replaced with the name of the ASN 1 module in which the information object is defined C Code Generation 93 Legacy Table Constraint Model For C a global variable is generated to hold the information object definition This is very similar to the code generated for a value definition An example of an information object definition that is derived from the ASN 1 ATTRIBUTE class above is as follows name ATTRIBUTE WITH SYNTAX VisibleString ID 05 Dan PEF This results in the generation of the following C constant ATTRIBUTE name Code generated in information object initialization function name TypeSize sizeof _name_Type name encodeType amp asnlE__name_Type name decodeType amp asnlD__name_Type name id numids 3 name id subid 0 0 name id subid 1
48. So the call to the memFreeAll method that is defined in the ASN C_Type base class will force all memory held at that point to be released Performance Considerations Dynamic Memory Management Please refer to Performance Considerations Dynamic Memory Management in the BER Decode Functions section for a discussion of memory management performance issues All of the issues that apply to BER and DER also apply to PER as well 200 Generated Octet Encoding Rules OER Functions Generated OER Encode Functions OER encode decode functions are generated when the oer switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C OER encode function is generated This function will convert a populated C variable of the given type into an OER encoded ASN 1 message C is not directly supported for OER however it is possible to call the generated C functions from a C program Generated C Function Format and Calling Pa rameters The format of the name of each generated PER encode function is as follows OEREnc_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all gene
49. This option is used to generate special code for table constraints in ASN 1 specifications that have a common pattern as found in many of the 3rd Generation Partnership Project 3GPP specifications Specifications having this pat tern include NBAP RANAP S1AP and X2AP ASNIC can take advantage of this common pattern to generate more efficient code Note This option is deprecated The new option that provides the same functionality is table unions which may be used to replace the 3gpp tables option combination appInfo lt items gt This option only has meaning when generating an XML schema definitions XSD file using the xsd option It instructs the compiler to generate an XSD application information section lt appinfo gt for certain ASN 1 only items The items are speci Running ASNIC from the Command line Option Argument Description fied as a comma delimited list Valid values for items are tags enum and ext lt items gt is an optional parameter If it is not specified it is assumed that application informa tion should be produced for all three item class es ASN 1 tags ASN 1 enumerations and ex tended elements array none This option specifies that an array type will be used for SEQUENCE OF SET OF constructs arraySize lt size gt This option specifies the size of array variable asn 1 lt filename gt This option causes pretty printed ASN
50. a a Note that the name for the aa element type is x a aa It contains both the name for a at level 1 and aa at level 2 The concatanation of all of the intermdeiate element names can lead to very long names in some cases To get around the problem the shortnames command line option can be used to form shorter names In this case only the type name and the last element name are used 56 SEQUENCE In the example above this would lead to an element name of x aa The disadvantage of this is that the names may not always be unique If using this option results in non unique names an _n suffix is added where n is a sequential number to make the names unique Note that although the compiler can handle embedded constructed types within productions it is generally not considered good style to define productions this way It is much better to manually define the constructed types for use in the final production definition For example the production defined at the start of this section can be rewritten as the following set of productions X SEQUENCE al INTEGER a2 BOOLEAN OCTET STRING SEQUENCE XxX X Y y This makes the generated code easier to understand for the end user Unnamed Elements Note As of X 680 unnamed elements are not allowed elements must be named ASN1C still provides backward compatibility support for this syntax however In an ASN
51. a few bytes of memory can result in a large block being allocated Common run time functions are available for controlling the memory allocation process First the default size of a memory block as allocated by the nibble allocation algorithm can be changed By default this value is set to 4K bytes The run time function r MemSetDefBlkSize can be called to change this size This takes a single argument the value to which the size should be changed It is also possible to change the underlying functions called from within the memory management abstraction layer to obtain or free heap memory By default the standard C malloc realloc and free functions are used These can be changed by calling the rtMemSetAllocFuncs function This function takes as arguments function pointers to the allocate reallocate and free functions to be used in place of the standard C functions Another run time memory management function that can improve performance is rtMemReset This function is useful when decoding messages in a loop It is used instead of rtMemFree at the bottom of the loop to make dynamic memory available for decoding the next message The difference is that rtMemReset does not actually free the dynamic memory It instead just resets the internal memory management parameters so that memory already allocated can be reused Therefore all the memory required to handle message decoding is normally allocated within the first few passes of the loop From t
52. a generated structure with this value the rtsetorp utility function can be used see the C C Run Time Library Reference Manual for a full description of this function In addition the C base type for this construct asN1TobjId contains constructors and assignment operators that allow direct assignment of values in this form to the target variable Constructed Type Values ASNIC will generate code for following remaining value definitions only when their use is required in legacy table constraint validation code SEQUENCE e SET SEQUENCE OF e SET OF 78 Constructed Type Values CHOICE Note SEQUENCE SET SEQUENCE OF SET OF and CHOICE values are available only when the tables option is selected The values are initialized in a module value initialization function The format of this func tion name is as follows init_ lt ModuleName gt Value OSCTXT pctxt Where lt ModuleName gt would be replaced with the name of the module containing the value specifications The only required argument is an initialized context block structure used to hold dynamic memory allocated in the creation of the value structures If the value definitions are used in table constraint definitions then the generated table constraint processing code will handle the initialization of these definitions otherwise the initialization function must be called explicitly SEQUENCE or SET Value Specification The mapping of an ASN
53. an XML namespace The calling sequence for each decode function is as follows status lt ns gt XmlDec_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The pvalue argument is a pointer to a variable to hold the decoded result This variable is of the type generated from the ASN 1 production The decode function will automatically allocate dynamic memory for variable length fields within the structure This memory is tracked within the context structure and is released when the context structure is freed The function returns the status of the decode operation Status code zero indicates the function was successful A negative value indicates decoding failed Return status values are defined in the rtxErrCodes h include file The reason text and a stack trace can be displayed using the rtxErrPrint function Procedure for Calling C Decode Functions This section describes the step by step procedure for calling a C XML decode function This method must be used if C code generation was done This method can also be used as an a
54. an infor mation object definition ASN E UNDEFCLAS This indicates that the specified class is not defined within context of the module that uses it ASN E INVFIELD This indicates the specified class field is not valid it must be defined ASN E UNDEFOSET ASN E INVVALELM This indicates that ASN1C was unable to find the specified object set in the context of the module in which it s used An invalid value was supplied for an element in a type ASN E MISVALELM This indicates that a non optional element is missing a val ue when it should have one ASN E INVLIDENT This indicates that an invalid identifier was specified in an enumeration ASN E FILNOTFOU ASN E INVSIZE This indicates that the requested file was not found This indicates that an invalid size specification for a type was provided check size constraints for base types ASN E UNRESOBJ This indicates that the specified information object could not be resolved within the context of the named module ASN E TOOMANY This indicates that too many sub elements for the specified type were provided ASN E LOOPDETECTED ASN E INVXMLATTR This indicates a loop was detected in the course of code generation typically this is raised during test code gener ation This indicates that the specified attribute type must be a simple type ASN E INTERNAL This indicates that internal structures used for generating cod
55. an output filename is specified after the genPrtToStrm qualifier all functions are written to that file Before calling generated print to stream functions a callback function should be registered Oth erwise a default callback function will be used that directs the print stream to the standard output device The callback function is declared as void rtxPrintCallback void pPrntStrmInfo const char fmtspec va_list arglist 242 Print Format The first parameter is user defined data which will be passed to each invocation of the callback function This parameter can be used to pass print stream specific data for example a file pointer if the callback function is to output data to a file The second and third parameters to the callback function constitute the data to be printed in the form of format specification followed by list of arguments A simple callback function for printing to file can be defined as follows void writeToFile void pPrntStrmInfo const char fmtspec va_list arglist FILE fp FILE pPrntStrmiInfo vfprintf fp fmtspec arglist Once the callback function is defined it has to be registered with the runtime library There are two types of registrations possible 1 global which applies to all print streams and 2 context level which applies to print streams associated with a particular context For registering a global callback use rtxSetGlobalPrintStream rtxPrintC
56. and very common single level nested SEQUENCE OF construct might be as follows A SEQUENCE OF SEQUENCE a INTEGER b BOOLEAN In this case a temporary type is generated for the element of the SEQUENCE OF production This results in the following two equivalent ASN 1 types A element SEQUENCE a INTEGER b BOOLEAN A SEQUENCE OF A element These types are then converted into the equivalent C or C typedefs using the standard mapping that was previously described SEQUENCE OF Type Elements in Other Constructed Types Frequently a SEQUENCE OF construct is used to define an array of some common type in an element in some other constructed type for example a SEQUENCE An example of this is as follows SomePDU SEQUENCE addresses SEQUENCE OF AliasAddress 64 SET OF Normally this would result in the addresses element being pulled out and used to create a tempo rary type with a name equal to somepDU addresses as follows SomePDU addresses SEQUENCE OF AliasAddress SomePDU SEQUENCE addresses SomePDU addresses However when the SEQUENCE OF element references a simple defined type as above with no additional tagging or constraint information an optimization is done to reduce the size of the gen erated code This optimization is to g
57. are deleted or go out of scope Reference counting of a context variable shared by both interfaces is used to accomplish this Decoding a Series of Messages Using the C Control Class Interface The above example is fine as a sample for decoding a single message but what happens in the more typical scenario of having a long running loop that continuously decodes messages The logic shown above would not be optimal from a performance standpoint because of the constant creation and destruction of the message processing objects It would be much better to create all of the required objects outside of the loop and then reuse them to decode and process each message A code fragment showing a way to do this is as follows include Employee h include file generated by ASNIC include rtbersrc ASNIBERDecodeStream h include rtxsrc OSRTFileInputStream h int main 184 Generated Streaming C Decode Method Format and Calling Parameters ASNITAG tag int i len const char filename message dat OSBOOL trace TRUE Decode ASNIBERDecodeStream in new OSRTFileInputStream filename if in getStatus 0 in printErrorInfo return 1 ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ msgData for FP A if in peekTagAndLen tag len 0 printf peekTagAndLen failed n in printErrorInfo return 1 Now switch on initial tag v
58. as well Generated Type Assignments If the information object contains an embedded type definition it is extracted from the definition to form a new type to be added to the generated C or C code The format of the new type name is as follows _ lt ObjectName gt _ lt FieldName gt where lt object Name gt is replaced with the information object name and lt rieldName gt is replaced with the name of the field from within the object Information Object Set Table constraint processing code to support Information Object Sets is generated in a header and source file with a C struct C class to hold the values The name of the header and source file are of the following format lt ModuleName gt Table h lt ModuleName gt Table c cpp In this definition lt ModuleName gt would be replaced with the name of the ASN 1 module in which the information object is defined C Code Generation AC global variable is generated containing a static array of values for the ASN 1 CLASS definition Each structure in the array is the equivalent C structure representing the corresponding ASN 1 information object An example of an Information Object Set definition that is derived from the ASN 1 ATTRIBUTE class above is as follows SupportedAttributes ATTRIBUTE name commonName This results in the generation of the following C constant ATTRIBUTE SupportedAttributes 2 int SupportedAttributes_Size 2 Code generate
59. assigned to a value of the type This constant is set to 128 as per the ASN 1 standard The ASN TObjld type used in the C mapping is defined in ASNITObjId h This class extends the C ASN OBJID structure and adds many additional constructors and helper methods See the ASNIC C C Common Run time Reference Manual for more details RELATIVE OID The ASN 1 RELATIVE OID type is converted into a C or C structured type that is identical to that of the OBJECT IDENTIFIER described above ASN 1 production lt name gt RELATIVE OID Generated C code typedef ASNI1OBJID lt name gt Generated C code typedef ASN1TObjJId ASN1T_ lt name gt A RELATIVE OID is identical to an OBJECT IDENTIFIER except that it does not contain the restriction on the initial two arc values that they fall within a certain range see the X 680 standard for more details on this REAL The ASN 1 REAL type is mapped to the C type OSREAL In the global include file osSysTypes h OSREAL is defined to be a double ASN 1 production ASN 1 production Generated C code typedef OSREAL lt name gt Generated C code typedef OSREAL ASN1T_ lt name gt 54 SEQUENCE SEQUENCE This section discusses the mapping of an ASN 1 SEQUENCE type to C The C mapping is similar but there are some differences These are discussed in the C Mapping of SEQUENCE subsection at the end of this section An ASN 1 SEQUENCE is a cons
60. buffer allocation is a good alternative Using the form of the ASN PEREncodeBuffer constructor that does not include buffer address and size arguments specifies dynamic buffer allocation This constructor only requires a Boolean value to specify whether aligned or unaligned encoding should be performed aligned is true The following code fragment illustrates PER encoding using a dynamic buffer include employee h include file generated by ASNI1C main OSOCTET msgptr int msglen stat OSBOOL aligned TRUE Create an instance of the compiler generated class This example does dynamic encoding no message buffer is specified ASN1PEREncodeBuffer encodeBuffer aligned ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ encodeBuffer msgData Populate msgData within the class variable msgData name givenName SMITH Encode if stat employee Encod 0 l printf Encoding was successful n printf Hex dump of encoded record n ncodeBuffer hexDump printf Binary dump n 192 Procedure for Using the C Control Class Encode Method encodeBuffer binDump employee Get start of message pointer and length msgptr encodeBuffer getMsgPtr len encodeBuffer getMsgLen else printf Encoding failed n encodeBuffer printErroriInfo exit 0 return 0 It is al
61. by invoking rtxErrPrint to print the details of the error contained within the con text variable 35 RTERR_PATMATCH Pattern match error This status code is returned by the decoder when a value in an XML instance does not match the pattern facet defined in the XML schema It can also be returned by numer ic encode functions that cannot format a numer ic value to match the pattern specified for that value 36 RTERR_ATTRMISRQ Missing required attribute This status code is re turned by the decoder when an XML instance is 274 General Status Messages Error Code Error Name Description missing a required attribute value as defined in the XML schema 37 RTERR_HOSTNOTFOU Host name could not be resolved This status code is returned from run time socket functions when they are unable to connect to a given host computer 38 RTERR_HTTPERR HTTP protocol error This status code is re turned by functions doing HTTP protocol op erations such as SOAP functions It is returned when a protocol error is detected Details on the specific error can be obtained by calling rtxEr rPrint 39 RTERR_SOAPERR SOAP error This status code when an error is detected when tryingto execute a SOAP opera tion 40 RTERR_EXPIRED Evaluation license expired This error is returned from evaluation versions of the run time library when the hard coded evaluation period
62. compiling the generat 10 Running ASNIC from the Command line Option Argument Description ed C or C code into a Dynamic Link Library DLL genMakeLib lt filename gt This option instructs the compiler to generate a portable makefile for compiling the generated C or C code into a static library file genPrint lt filename gt This option allows the specification of a C or C print source c or cpp file to which generated print functions will be written Print functions are de bug functions that allow the contents of generat ed type variables to be written to stdout The lt filename gt argument to this option is op tional If not specified the print functions will be written to lt modulename gt Print c where lt mod ulename gt is the name of the module from the ASN 1 source file genPrtToStr prtToStr lt filename gt This option allows the specification of a C or C source c or cpp file to which gener ated print to string functions will be written Print to string functions are similar to print functions except that the output is written to a user provided text buffer instead of stdout This makes it possible for the use to display the re sults on different output devices for example in a text window The lt filename gt argument to this option is op tional If not specified the functions will be written to lt modulename gt Print c where lt mod ulename
63. element in the resulting ASN 1 SEQUENCE assignment e If the sequence contains a repeating element denoted by having a maxOccurs attribute with a value greater than one then a SEQUENCE OF type for this element is used in the ASN 1 SEQUENCE for the element e If attributes are defined within the complex type container containing the sequence group at tributes are defined these attribute declarations are added to the resulting ASN 1 as element dec larations as per the X 694 standard In XML encodings these appear as attributes in the markup in binary encodings they are elements Example lt xsd complexType name Name gt lt xsd sequence gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string minOccurs 0 gt lt xsd element name familyName type xsd string gt lt xsd sequence gt lt xsd complexType gt would result in the creation of the following C type definition typedef struct EXTERN Name struct unsigned initialPresent 1 m const OSUTF8CHAR givenName const OSUTF8CHAR initial const OSUTF8CHAR familyName Name xsd all The xsd all type is similar to an ASN 1 SET in that it allows for a series of elements to be specified that can be transmitted in any order However due to some technicalities with the type itis modeled in X 694 to be a SEQUENCE type with a special embedded array called order This array specifies
64. element2 name gt ae eek The lt type1 gt and lt type2 gt placeholders represent the equivalent C types for the ASN 1 types lt e1 ement1 type gt and lt element2 type gt respectively This form of the structure will be generated if the internal types are primitive lt tempName1 gt and lt tempName2 gt are formed using the algorithm de scribed above for pulling structured types out of the definition This form is used for constructed elements and elements that map to structured C types The example above would result in the following generated C typedefs typedef struct A_x OSINT32 al OSBOOL a2 Ax typedef struct A_y OSUINT32 numocts OSOCTET data 10 A_y typedef struct A A_X X A_y yi A In this case elements x and y map to structured C types so temporary typedefs are generated In the case of nesting levels greater than two all of the intermediate element names are used to form the final name For example consider the following type definition that contains three nesting levels X SEQUENCE a SEQUENCE aa SEQUENCE x INTEGER y BOOLEAN bb INTEGER In this case the generation of temporary types results in the following equivalent type definitions X a aa SEQUENCE x INTEGER y BOOLEAN X a SEQUENCE aa X a aa bb INTEGER X SEQUENCE X
65. encode function can be called the user must first initialize an encoding context block structure The context block is initialized by calling rt nitContext to initialize a context block 218 Procedure for Calling C Encode Functions structure The user then must call the xersetEncBufptr function to specify a message buffer to receive the encoded message Specification of a dynamic message buffer is possible by setting the buffer address argument to null and the buffer size argument to zero This function also also allows specification of whether standard XER or canonical XER encoding should be done An encode function can then be called to encode the message If the return status indicates success 0 then the message will have been encoded in the given buffer XER encoding starts from the beginning of the buffer and proceeds from low memory to high memory until the message is com plete This differs from BER where encoding was done from back to front Therefore the buffer start address is where the encoded XER message begins The length of the encoded message can be obtained by calling the xerGetMsgLen run time function If dynamic encoding was specified i e a buffer start address and length were not given the run time routine xerGetMsgPtr can be used to obtain the start address of the message This routine will also return the length of the encoded message A program fragment that could be used to encode an employee record is as f
66. for are those determined to be Protocol Data Units or PDU s for short A PDU is a top level message type in a specification These are the only types control classes are required for because the only purpose of a control class is to provide the user with a simplified calling interface for encoding and decoding a message They are not used in any of the ASNIC internally generated logic the exception to this rule is the XER XML encoding rules where they are used internally and still must be generated for all types A type is determined to be a PDU in two different ways 1 If it is explicitly declared to be PDU via the lt isPDU gt configuration setting or pdu com mand line option 2 If no explicit declarations exist a type is determined to be a PDU if it is not referenced by any other types In the employee sample program EmployeeNumber would not be considered to be a PDU because it is referenced as an element within the Employee production For the purpose of this discussion we will assume EmployeeNumber was explicitly declared to be a PDU via a configuration setting or command line specification ASN1C_EmployeeNumber is the control class declaration The purpose of the control class is to provide a linkage between the message buffer object and the ASN 1 typed object containing the message data The class provides methods such as EncodeTo and DecodeFrom for encoding and decoding the contents to the linked objects It also provides
67. function can be called directly if the type of message is known if msgtag TV_PersonnelRecord 166 Generated C Function For mat and Calling Parameters Step 3 Call decode function note last two args should always be ASNIEXPL and 0 status asnlD_PersonnelRecord amp ctxt amp employee ASNIEXPL 0 Step 4 Check return status if status 0 process received data in employee variable Remember to release dynamic memory when done rtxMemFree amp ctxt else error processing else check for other known message types Decoding a Series of Messages Using the C Decode Functions The above example is fine as a sample for decoding a single message but what happens in the more typical scenario of having a long running loop that continuously decodes messages It will be necessary to put the decoding logic into a loop main OSOCTET msgbuf 1024 ASNITAG msgtag int msglen OSCTXT CEEX PersonnelRecord employee Step 1 Initialize a context variable for decoding if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 for 7 logic to read message into msgbuf xd_setp amp ctxt msgbuf 0 amp msgtag amp msglen Step 2 Test message tag for type
68. generating code in one of two forms for information in an object specification 1 Simple form in this form references to variable type fields within standard types are simply treated as open types and an open type placeholder is inserted 2 Table unions form in this form all of the classes objects and object sets within a specification result in the generation of code for parsing and formatting the information field references within 127 Generated Information Object Table Structures standard type structures Open types with relational constraints result in the generation of C union structures that enumerate all of allowed fields as defined by the constraint This form is selected by using the table unions command line option 3 Legacy table form this is similar to 2 in that all information object related items result in the generation of additional code In this case however instead of a union structure being generated for open types with relational constraints a void pointer is used to hold an object in decoded form This form is selected using the tables command line option To better understand the support in this area the individual components of Information Object specifications are examined We begin with the CLASS specification that provides a schema for Information Object definitions A sample class specification is as follows OPERATION CLASS amp operationCode CHOI
69. givenName IA5String initial IA5String familyName IA5String feted END By default the following c files would be generated note this assumes no additional code gen eration options were selected Employee c EmployeeEnc c EmployeeDec c If maxcfiles was selected as in the following command line asnlc employee asn c ber trac maxcfiles Running ASNIC with the maxcfiles option the following c files for this type would be generated for the Name type asnlD_Name c asnlE_Name c These contain the functions to decode Name and encode Name respectively Similar files would be generated for the other productions in the module as well Generated C files In general the generation logic for C is similar to the logic for C Instead of the c file exten sion cpp is used 116 Generated C files lt moduleName gt cpp Common definitions and functions for ex ample asnlFree_ lt type gt and or global val ue constant definitions This file also contains constructors destructors and all methods for ASNI1C_ lt Type gt and ASNIT_ lt Type gt control classes lt moduleName gt Enc cpp C encode functions and C encode methods lt moduleName gt Dec cpp C decode functions and C decode methods If additional options are used such as genPrint genCopy etc additional files will be generated Filename Description lt moduleName gt Copy cpp copy f
70. gt 1s the name of the ASN 1 pro duction for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePre fix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production lt namespace gt is set using the ASNIC namespace com mand line argument Note that this should not be confused with the notion of an XML namespace The calling sequence for each encode function is as follows status lt ns gt XmlEnc_ lt name gt OSCTXT pctxt lt name gt value const OSUTF8CHAR elemName const OSUTF8CHAR nsPrefix In this definition lt ns gt is short for lt namespace gt and lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The value argument contains the value to be encoded or holds a pointer to the value to be encoded This variable is of the type generated from the ASN 1 production The object is passed by value if it is a primitive ASN 1 data type such as BOOLEAN INTEGER ENUME
71. gt is the name of the module from the ASN 1 source file genPrtToStrm ToStrm prt lt filename gt This option allows the specification of a C or C source c or cpp file to which generat ed print to stream functions will be written Print to stream functions are similar to print functions except that the output is written to a us er provided stream instead of stdout The stream is in the form of an output callback function that can be set within the run time context making it possible to redirect output to any type of device 11 Running ASNIC from the Command line Option Argument Description The lt filename gt argument to this option is op tional If not specified the functions will be written to lt modulename gt Print c where lt mod ulename gt is the name of the module from the ASN 1 source file genTables tables lt filename gt This option is used to generate additional code for the handling of table constraints as defined in the X 682 standard See the Generated Infor mation Object Table Structures section for ad ditional details on the type of code generated to support table constraints Note An alternaitve option for C C is table unions which gener ates union structures for table constraints These are generally easier to work with then the legacy void pointer approach used in this option genTest lt filename gt This option allow
72. is added because the object set is extensible and it therefore may contain a value that is currently not included in the set 130 Legacy Table Form Code Generation Legacy Table Form Code Generation In the legacy form of table constraint code generation the following structure would be generated for the Invoke type above typedef struct EXTERN Invoke OSINT32 invokeID _OPERATION_operationCode opcode ASN1Object argument This is almost identical to the type generated in the simple case The difference is the ASNI Object type or ASN TObject for C that is used instead of ASN OpenType This type is defined in the asnItype h run time header file as follows typedef struct ASN1Object ASN10OpenType encoded void decoded OSINT32 index This holds the value to be encoded or decoded in both encoded or decoded form The way a user uses this to encode a value of this type is as follows 1 Populate a variable of the type to be used as the argument to the invoke type 2 Plug the address of this variable into the decoded void pointer in the structure above 3 Populate the remaining Invoke type fields 4 Encode the Invoke type to produce the final message Note that in this case the intermediate type does not need to be manually encoded by the user The generated encoder has logic built in to encode the complete message using the information in the generated tables Additional Code Generated wit
73. is down or otherwise unreachable 55 RTERR_NOCONN Not connected This status code is returned when an operation is issued on an unconnected socket 56 RTERR_CONNREFUSED Connection refused This status code is returned when an attempt to communicate on an open socket is refused by the host 276 ASN 1 specific Status Messages Error Code Error Name Description 57 RTERR_INVSOCKOPT 58 RTERR_SOAPFAULT Invalid option This status code is returned when an invalid option is passed to socket This error is returned when the decoded SOAP envelope is a fault message 59 RTERR_MARKNOTSUP This error is returned when an attempt is made to mark a stream position on a stream type that does not support it 60 RTERR_NOTSUPP Feature is not supported This status code is re turned when a feature that is currently not sup ported is encountered 61 RTERR_CODESETCONVFAIIThis status code is returned when transcoding from one character set to another one for exam ple from UTF 8 to UTF 16 and a conversion error occurs ASN 1 specific Status Messages The following table describes status messages that may arise during the course of encoding or decoding an ASN 1 message The errors below indicate that while the system was able to read the data successfully it was unable to decode it properly Error Code Error Name Description 2 ASN_OK_ F
74. lik vent handlers stream generate stream based encode decode functions strict do strict checking of table constraint conformance tables generate table constraint functions table unions generate union structures for table constraints param lt name gt lt value gt create types from param types using given value prtToStr lt filename gt generate print to string functions C C prtToStrm lt filename gt generate print to stream functions C C genTest lt filename gt generate sample test functions reader generate sample reader program writer generate sample writer program compare lt filename gt generate comparison functions C C copy lt filename gt generate copy functions C C maxcfiles generate separate file for each function C C XSD options lt items gt can be tags appinfo tags enum ext appinfo for ASN 1 items enum and or ext all if lt items gt not given non native attributes for lt items gt lt items gt is same as for appinfo appinfo lt items gt generat ex default attrs lt items gt generat targetns lt namespace gt no targ useAsnlxXsd Specify target namespace lt namespace gt is namespace URI if not given declaration is added t namespac reference types in asnl xsd schema Running ASNIC from the Command line Symbian options symbian lt items gt generate code for Symbian OS lt items gt can be dll e g s
75. loop to start again with no outstanding memory allocations for the next pass If the buffer already contains multiple BER messages encoded back to back then it is necessary to modify the buffer pointer in each iteration The getByteIndex method should be used at the end of loop to get the current offset in the buffer This offset should be used with the decode buffer object s setBuffer method call at the beginning of the loop to determine the correct buffer pointer and length OSUINT32 offset 0 for offset lt msglen set buffer pointer and its length to decode 172 BER Decode Performance Enhancement Techniques decodeBuffer setBuffer amp msgbuf offset msglen offset int curlen int msglen offset status decodeBuffer ParseTagLen msgtag curlen if status 0 handle error Now switch on initial tag value to determine what type of message was received switch msgtag case TV_PersonnelRecord compiler generated constant if status employee Decod 0 decoding successful data in employeeData process received data else error processing break default handle unknown message type her switch get new offset offset decodeBuffer getByteIndex Need to reinitialize objects for next iteration if it is not last iteration if offset lt msglen employee memFreeAll
76. lt object gt Exceptions are not used in ASNIC C therefore the user must fetch the status value follow ing a call such as this in order to determine if it was successful The getStatus method in the ASN1DecodeStream class is used for this purpose Also the method Decode without parameters is supported for backward compatibility In this case it is necessary to create a control class object i e ASN1C_ lt prodName gt using an input stream reference as the first parameter and a reference to a variable of the generated type as the second parameter of the constructor Procedure for Using the Streaming C Control Class Decode Method Normally the receiving message can be one of several different message types It is therefore nec essary to determine the type of message that was received so that the appropriate decode function can be called to decode it The ASN BERDecodeStream class has standard methods for parsing the initial tag length from a message to determine the type of message received These calls are used in conjunction with a switch statement on generated tag constants for the known message set Each switch case statement contains logic to create an object instance of a specific ASNIC generated control class and to invoke and then to invoke that object s decode method A program fragment that could be used to decode an employee record is as follows include Employee h include file generated by ASNI1C include r
77. messages It hides most of the complexity of calling the encode decode functions directly BER DER or PER Class Definition The general form of the class definition for BER DER or PER encoding rules is as follows class ASN1C_ lt name gt public ASN1CType protected ASN1T_ lt name gt amp msgData public ASN1C_ lt name gt ASNI1T_ lt name gt amp data ASN1C_ lt name gt ASN1MessageBufferlIF amp msgBuf ASN1T_ lt name gt amp data standard encode decode methods defined in ASN1CType base class int Encode 124 BER DER or PER Class Definition int Decode stream encode decode methods int EncodeTo ASN1MessageBufferIF amp msgBuf int DecodeFrom ASN1MessageBufferIF amp msgBuf pi The name of the generated class is ASNIC_ lt name gt where lt name gt is the name of the production The only defined attribute is a protected variable reference named msgData of the generated type Two constructors are generated The first is for stream operations and allows the control class to be created using only a reference to a variable of the generated type The EncodeTo and DecodeFrom methods can then be used to encode or decode directly to and from a stream The lt lt and gt gt stream operators can be used as well The second constructor is the legacy form that allows a message buffer to be associated with a data variable at the time of creation The Encode and Decode meth
78. method of the encode buffer object A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNI1C main const OSOCTET msgptr OSOCTET msgbuf 1024 int msglen stat OSBOOL canonical FALSE step 1 instantiate an instance of the XER encod buffer class This example specifies a static message buffer ASN1XEREncodeBuffer encodeBuffer msgbuf sizeof msgbuf 220 Generated XER Decode Functions canonical step 2 populate msgData with data to be encoded ASN1T_PersonnelRecord msgData msgData name givenName SMITH step 3 instantiate an instance of the ASN1C_ lt ProdName gt class to associate th ncode buffer and message data ASN1C_PersonnelRecord employ encodeBuffer msgData steps 4 and 5 encode and check return status if stat employee Encod 0 printf encoded XML message n printf const char msgbuf printf n step 6 get start of message pointer and message length start of message pointer is start of msgbuf call getMsgLen to get message length msgptr encodeBuffer getMsgPtr will return amp msgbuf len encodeBuffer getMsgLen else printf Encoding failed n encodeBuffer printErroriInfo exit 0 msgptr and len now describe fully encode
79. msgData return this The generated ASNIT lt name gt structure will also contain an additional copy constructor if C is used and PDU generation is not disabled A destructor is also generated if the type contains dynamic memory fields This destructor will free the dynamic memory upon destruction of the type instance For example typedef struct EXTERN ASN1T_PersonnelRecord public ASNITPDU ASN1T_PersonnelRecord m uniPresent 0 m seqOfseqPresent 0 ASN1T_PersonnelRecord ASN1C_PersonnelRecord srcData ASN1T_PersonnelRecord ASN1IT_PersonnelRecord This constructor is used to create an instance of the ASNIT_ lt name gt type from an ASNIC_ lt name gt control class object Memory Management of Copied Items Prior to ASNIC version 5 6 dynamic memory of decoded or copied items would only be available as long as the control class instance and or the message buffer object used to decode or copy the item remained in scope or was not deleted This restriction no longer exists as long as the type being copied is a Protocol Data Unit PDU The copied item will now hold a reference to the context variable used to create the item and will increment the item s reference count This reference is contained in the ASN TPDU base class variable from which PDU data types are now derived The dynamic memory within the item will persist until the item is deleted 247 Generated Test Functions
80. oid2 3 0 1 2 logic to read message into msgbuf Step 1 Initialize a context variable for decoding if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check licens return 1 xd_setp amp ctxt msgbuf 0 amp msgtag amp msglen step 2 call module initialization functions Test_init amp ctxt Step 3 Call decode function status asnlD_Invoke amp ctxt amp invoke ASNIEXPL 0 Step 4 Check return status if status 0 process received data in amp invoke opcode if rtCmpTCOID invoke variable amp 0idl 0 argument is a VisibleString ASN1VisibleString pArg ASN1VisibleString else if rtCmpTCOID amp invoke opcode msgData argument decoded amp 0id2 0 argument is an INTE OSINT32 OSINT32 arg G ER msgData argument decoded generated by ASNI1C y n 139 General Procedures for Encoding and Decoding Remember to release dynamic memory when done ASNIMEMFREE amp ctxt else error processing General Procedures for Encoding and Decoding Encoding functions and methods generated by the ASN1C compiler are designed to be similar in use across the different encoding rule types In other words if you have written an application to use the Basic Encoding Rules B
81. one must be careful to release this memory when done with the structure If the built in memory management functions macros are used 7txMem all memory used for the variables is automatically released when rtxMemFree is called Open Type Note The X 680 Open Type replaces the X 208 ANY or ANY DEFINED BY constructs An ANY or ANY DEFINED BY encountered within an ASN 1 module will result in the gen eration of code corresponding to the Open Type described below An Open Type as defined in the X 680 standard is specified as a reference to a Type Field in an Information Object Class The most common form of this is when the Type field in the built in TYPE IDENTIFIER class is referenced as follows TYPE IDENTIFIER amp Type See the section in this document on Information Objects for a more detailed explanation The Open Type is converted into a C or C structure used to model a dynamic OCTET STRING type This structure contains a pointer and length field The pointer is assumed to point at a string of previously encoded ASN 1 data When a message containing an open type is decoded the address of the open type contents field is stored in the pointer field and the length of the component is stored in the length field The general mapping of an Open Type to C C is as follows ASN 1 production lt name gt ANY Generated C code typedef ASN1OpenType lt name gt Generated C code typedef ASN1TOpenType lt name gt
82. option added in ASNIC version 6 0 is domtest This is similar to gentest except that data for the test variables is not random it is extracted from an XML Document Object Model DOM tree at run time In order to use this capability it is necessary to have the libxml2 http xmlsoft org XML parser installed on your system Calls are then made to parse a given XML document and create a DOM tree Data from the DOM tree will then be transfered to data varaibles of generated structures This has the same end result as decoding the XML documents using the XML decoder Generated Sample Programs In addition to test functions it is possible to generate writer and reader sample programs These programs contain sample code to populate and encode an instance of ASN 1 data and then read and decode this data respectively These programs are generated using the genwriter and genreader command line switches 249 250 Event Handler Interface The events command line switch causes hooks for user defined event handlers to be inserted into the generated decode functions What these event handlers do is up to the user They fire when key message processing events or errors occur during the course of parsing an ASN 1 message They are similar in functionality to the Simple API for XML SAX that was introduced to provide a simple interface for parsing XML messages The notypes option can be used in conjunction with the events option to ge
83. option allows the specification of a C or C source c or cpp file to which all of the gen erated encode decode functions will be written If not specified the default is to write to a series of c or cpp files based on the ASN 1 module name s of the documents being compiled compact None This option instructs the compiler to generate more compact code at the expense of some con Running ASNIC from the Command line Option Argument Description straint and error checking This is an optimiza tion option that should be used after an applica tion is thoroughly tested compat lt versionNumber gt Generate code compatible with an older version of the compiler The compiler will attempt to generate code more closely aligned with the giv en previous release of the compiler lt versionNumber gt is specified as x x for exam ple compat 5 2 config lt filename gt This option is used to specify the name of a file containing configuration information for the source file being parsed A full discussion of the contents of a configuration file is provided in the Compiler Configuration File section cppns lt namespace gt This option is used to add a C namespace name to generated C files depends None This option instructs the compiler to generate a full set of header and source files that con tain only the productions in the main file being co
84. parameters then all code will be placed in one source file with name lt filename gt Maximum Lines per File In each of the cases above it is possible to specify an approximate maximum number of lines that each of the generated c files may contain This is done using the maxlines option If maxlines is specified with no parameter a default maximum number of lines 50 000 will be set otherwise the given value will be used If the given maximum lines limit is surpassed in a file a new file will be started with an _1 appended for example lt moduleName gt Enc_l c Additional files will be numbered sequentially if necessary _2 _3 etc Note that this limit is a lower threshold and not exact A complete compilation unit for example a function will not be split because of this threshold The way it works is the threshold is checked before the output of a compilation unit If it is found to be exceeded a new file is started at that time Therefore a user should plan for a reserve to be in place above the limit to compensate for this overflow The reason for having this limit is because some C C compilers have problems with very large c files For example one product will not allow the debugger to work on lines in a file over the 64k threshold Use of the maxcfiles Option The maxcfiles option allows generation of more compact code by putting each encode decode copy compare etc function into a separate file This allow
85. print handler class definition or the defini tion could be added to an existing header file This file will contain a class derived from the AsnINamedEventHandler base class as follows class PrintHandler public AsnlNamedEventHandler protected const char mVarName int mIndentSpaces public PrintHandler const char varName PrintHandler void indent virtual void startElement const char name int index 1 virtual void endElement const char name int index 1 virtual void boolValue OSBOOL value other virtual contents method declarations In this definition we chose to add the mVarName and mIndentSpaces member variables to keep track of these items The user is free to add any type of member variables he or she wants The only firm requirement in defining this derived class is the implementation of the virtual methods We implement these virtual methods as follows In startElement we print the name equal sign and opening brace 253 How to Use It void PrintHandler startElement const char name int index indent printf Ss n name mIndentLevel In this simplified implementation we simply indent this is another private method within the class and print out the name equal sign and opening brace We then increment the indent level Note that this is a highly simplified form We don t even bother to check if the index argument is
86. production lt name gt OCTET STRING Generated C code typedef ASN1DynOctStr lt name gt Generated C code typedef ASN1TDynOctStr ASNIT_ lt name gt In this case different base types are used for C and C The difference between the two is the C version includes constructors assignment operators and other helper methods that make it easier to manipulate binary data The ASNI DynOctStr type 1 e the type used in the C mapping is defined in the asn type h header file as follows typedef struct ASN1DynOctStr OSUINT32 numocts const OSOCTET data ASN1DynOctStr The ASN TDynOctStr type is defined in the ASN TOctStr h header file This class extends the C ASN1DynOctStr class and adds many additional constructors and methods See the C C Com mon Run time Reference Manual for a complete description of this class Static sized OCTET STRING ASN 1 production 50 ENUMERATED lt name gt OCTET STRING SIZE lt len gt Generated C code typedef struct OSUINT32 numocts OSOCTET data lt len gt lt name gt Generated C code typedef struct OSUINT32 numocts OSOCTET data lt len gt ctors ASN1T_ lt name gt ASN1T_ lt name gt OSUINT32 _numocts const OSOCTET _data ASN1T_ lt name gt const char cstring assignment operators ASN1T_ lt name gt amp operator const char cstring ASNIT_ lt name gt Contents
87. released when both the OSXMLDecodeBuffer and ASN C_ lt ProdName gt ob jects go out of scope A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main const char filename message xml OSBOOL verbose FALSE trace TRUE int i stat logic to read message into msgbuf step 1 instantiate an XML decode buffer object OSXMLDecodeBuffer decodeBuffer filename step 2 instantiate an ASN1T_ lt ProdName gt object ASN1T_PersonnelRecord msgData step 3 instantiate an ASN1C_ lt ProdName gt object ASN1C_PersonnelRecord employ decodeBuffer msgData step 4 decode the record stat employee Decod ys step 5 check the return status if stat 0 process received data 237 Procedure for Using the C Control Class Decode Method else error processing decodeBuffer PrintErrorInfo step 6 free dynamic memory will be done automatically when both the decodeBuffer and employ objects go out of scope 238 Additional Generated Functions Generated Initialization Functions As of ASNIC version 6 0 initialization functions are automatically generated in previous ver sions it was necessary to use the gen nit option to force this action If for some reason a user does want initialization functions to be generated the no
88. standards It is capable of parsing advanced syntax including Information Object Specifications as defined in the ITU T X 681 standard as well as Parameterized Types as defined in ITU T X 683 The compiler is also capable of using table constraints as defined in ITU T X 682 to generate single step encoders and decoders that can encode or decode multi part messages in a single function call This release of the compiler contains a special command line option asnstd x208 that allows compilation of deprecated features from the older X 208 and X 209 standards These include the ANY data type and unnamed fields in SEQUENCE SET and CHOICE types This version can also parse type syntax from common macro definitions such as the OPERATION and ERROR macros in ROSE Using the Compiler Running ASN1C from the Com mand line The ASNIC compiler distribution contains command line compiler executables as well as a graph ical user interface GUI wizard that can aid in the specification of compiler options This section describes how to run the command line version the next section describes the GUI To test if the compiler was successfully installed enter asnic with no parameters as follows note if you have not updated your PATH variable you will need to enter the full pathname asnic You should observe the following display or something similar ASN1C Compiler Version 6 4 x Copyright c 1997 2011 Objective Systems Inc All Rights
89. storage class such as dynamic can be specified and applied to all productions in all modules This will cause dynamic storage pointers to be used for any embedded structures within all of the generated code to reduce memory consumption demands The specification of a module is done using the lt module gt lt module gt tag pair This tag pair can only be nested within the top level lt asniconfig gt section The module is identified by using the required lt name gt lt name gt tag pair or by specifying the name as an attribute for example lt module name MyModule gt Other attributes specified within the lt module gt section apply only to that module and not to other modules specified within the specification A complete list of all module attributes is provided in the table at the end of this section The specification of an individual production is done using the lt production gt lt production gt tag pair This tag pair can only be nested within a lt module gt section The production is identified by using the required lt name gt lt name gt tag pair or by specifying the name as an attribute for example lt production name MyProa gt Other attributes within the production section apply only to the ref erenced production and nothing else A complete list of attributes that can be applied to individual productions is provided in the table at the end of this section When an attribute is specified in more than one section
90. string point er char by default The chararray item can be used on strings with size constrains to specify a static character array variable be used section Name Values lt name gt production name lt name gt lt ctype gt byte intl6 uintl6 int32 uint32 int64 string chararray lt enumPrefix gt lt prefix text enumPrefix gt This is used to specify a prefix that will be applied to all generated enumerated identifiers within a module This can be used to prevent name clashes if multiple modules are involved in a compilation note this attribute is normally not needed for C enumerated identifiers be cause they are already wrapped in a structure to allows the type name to be used as an additional identifier 39 Compiler Configuration File Name Values Description lt format gt lt format gt base64 hex xmllist lt isBigInteger gt n a This is used to set format options specific to XER encoding The base64 or hex alternative is used to set the output format that binary da ta in OCTET STRING variables is displayed in in XML markup The xmllist alternative is used with SEQUENCE OF or SET OF types to denote that items should be displayed in XML space separated list format as opposed to a using a sep arate element for each list item This is a flag variable an empty element in XML terminology that specifies that this pro duction will be used to sto
91. struct generic table constraint value holder ASN10penType encoded void decoded OSINT32 index table index ASN1Object This allows a value of any ASN 1 type to be represented in both encoded and decoded forms Encoded form is the open type form shown above It is simply a pointer to a byte buffer and a count of the number of byes in the encoded message component The decoded form is a pointer to a variable of a specific type The pointer is void because there could be a potentially large number of different types that can be represented in the table constraint used to constrain a type field to a given set of values The index member of the type is for internal use by table constraint processing functions to keep track of which row in a table is being referenced In addition to this change in how open types are represented a large amount of supporting code is generated to support the table constraint validation process This additional code is described below Note that it is not necessary for the average user to understand this as it is not for use by users in accomplishing encoding and decoding of messages It is only described for completeness in order to know what that additional code is used for CLASS specification All of the Class code will be generated in a module class header file with the following filename format lt ModuleName gt Class h In this definition lt ModuleName gt would be replaced with the name of
92. the ASN 1 source file a C XER encode function is generated This function will convert a populated C variable of the given type into an XER encoded ASN 1 message i e an XML document If C code generation is specified a control class is generated that contains an Encode method that wraps this function This function is invoked through the class interface to encode an ASN 1 message into the variable referenced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each generated XER encode function is as follows asnlXE_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each encode function is as follows status asnlXE_ lt name gt OSCTXT pctxt lt name gt value const char elemName const char attributes In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant s
93. the C Encode Functions A common application of BER encoding is the repetitive encoding of a series of the same type of message over and over again For example a TAP3 batch application might read billing data out of a database table and encode each of the records for a batch transmission If a user was to repeatedly allocate free memory and reinitialize the C objects involved in the encoding of a message performance would suffer This is not necessary however because the C objects and memory heap can be reused to allow multiple messages to be encoded As example showing how to do this is as follows include employee h include file generated by ASNIC main const OSOCTET msgptr OSOCTET msgbuf 1024 int msglen OSCTXT EEX PersonnelRecord data Init context structure if stat rtInitContext amp ctxt 0 printf rtInitContext failed stat d n stat return 1 Encode loop starts here this will repeatedly use th objects declared above to encode the messages for 77 xe_setp amp ctxt msgbuf sizeof msgbuf logic here to read record from some source database flat file socket etc populate structure with data to be encoded data name SMITH call encode function if msglen asnlE_PersonnelRecord amp ctxt amp data ASNIEXPL gt 0 encoding successful get pointer to start of messa
94. the most specific application is always used For example assume a lt typePrefix gt qualifier is used within a module specification to specify a 33 Compiler Configuration File prefix for all generated types in the module and another one is used to a specify a prefix for a single production The production with the type prefix will be generated with the type prefix assigned to it and all other generated types will contain the type prefix assigned at the module level Values in the different sections can be specified in one of the following ways 1 Using the lt name gt value lt name gt form This assigns the given value to the given name For ex ample the following would be used to specify the name of the H323 MESSAGES module in a module section lt name gt H323 MESSAGES lt name gt 2 Flag variables that turn some attribute on or off would be specified using a single lt name gt entry For example to specify a given production is a PDU the following would be specified in a production section lt isPDU gt 3 An attribute list can be associated with some items This is normally used as a shorthand form for specifying lists of names For example to specify a list of type names to be included in the generated code for a particular module the following would be used lt include types TypeNamel1 TypeName2 TypeName3 gt The following are some examples of configuration specifications lt asnl
95. the order in which XML elements were received if XML decoding of an XML instance was done If this information were then retransmitted in binary using BER or PER the order information would be encoded and transmitted followed by the SEQUENCE elements in the declared order If the data were then serialized back into XML the order information would be used to put the elements back in the same order in which they were originally received The mapping to C type would be the same as for xsd sequence above with the addition of the special order array An example of this is as follows 99 xsd choice and xsd union lt xsd complexType name Name gt lt xsd all gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string gt lt xsd element name familyName type xsd string gt lt xsd all gt lt xsd complexType gt would result in the creation of the following C type definition typedef struct EXTERN Name struct OSUINT32 n OSUINT8 elem 3 _order const OSUTF8CHAR givenName const OSUTF8CHAR initial const OSUTF8CHAR familyName Name In this case the _order element is for the order element described earlier Normally the user does not need to deal with this item When the generated initialization is called for the type or C constructor the array will be set to indicate elements should be transmitted in the declared order If XML dec
96. to disable warnings output compiler warning messages nodatestamp do not put date time stamp in generated files C C options array use arrays for SEQUENCE OF SET OF types arraySize lt size gt specify the size of the array variable dynamicArray use dynamic arrays for SEQUENCE OF SET OF types linkedList use linked lists for SEQUENCE OF SET OF types hfile lt filename gt C or C header h filename default is lt ASN 1 Module Name gt h cfile lt filename gt C or C source c or cpp filename default is lt ASN 1 Module Name gt c genBitMacros generate named bit set clear test macros genFree generate memory free functions for all types hdrGuardPfx lt pfx gt add prefix to header guard defines in h files maxlines lt num gt set limit of number of lines per source file default value is 50000 noInit do not generate initialization functions noEnumConvert do not generate conversion functions for enumerated items BER CER DER PER only oh lt directory gt set output directory for header files static generate static elements not pointers cppNs lt namespace gt add a C namespace to generated code C only C C makefile project options genMake lt filename gt generate makefile to compile generated cod genMakeDLL lt filename gt generate makefile to build DLL genMakeLib lt filename gt generate makefile
97. to generate boilerplate reader and writer ap plications as well as randomized test data for populating a sample encoded message The items in the Protocol Data Units frame may be used in conjunction to select the appropriate PDU data type to be used in the sample programs The Debugging and Event Handlers frame contains options that generate code for adding trace diagnostics and event handling hooks into generated code It is possible to generate a type parser by generating only an event handler and no data types for the decoded messages This grants a great deal of flexibility in handling input data at the expense of generating pre defined functions for most common encoding and decoding tasks Users of embedded systems may find this useful as it will shrink the output considerably while allowing them fine control over decoding procedures 26 XSD Options The Other Options frame contains miscellaneous modifications to code output including type name resolution avoiding duplicate names date stamp removal useful when generated code will be stored in source control and a line item for including any new command line features not yet represented in the GUI XSD Options If the Generate equivalent XML schema XSD file option was checked in the Common Code Gen eration Options screen the following window will be presented for modifying the contents of the generated XSD XSD Generation Options E Generate Application Information An
98. to reduce the size of the generated code base by selecting only a subset of the types val ues in a specification for compilation Note that if a type or value is included that has dependent types or values for example the element types in a SEQUENCE SET or CHOICE all of the dependent types will be automatically included as well lt include encoders names gt lt include decoders names gt ASN 1 type names specified as an attribute list ASN 1 type names specified as an attribute list This item allows a list of ASN 1 types to be in cluded in the generated code for which only en code functions will be generated This item allows a list of ASN 1 types to be in cluded in the generated code for which only de code functions will be generated lt include memfree names gt ASN 1 type names specified as an attribute list This item allows a list of ASN 1 types to be included in the generated code for which only memory free functions will be generated lt include imports From name gt ASN 1 module name s specified as an attribute list This form of the include directive tells the com piler to only include types and or values in the generated code that are imported by the given module s 36 Compiler Configuration File Name Values Description lt exclude types names values names gt ASN 1 type or values names are specified as an a
99. to the C or C source file INTEGER and REAL value specifications cause define statements to be generated BOOLEAN Value A BOOLEAN value causes an extern statement to be generated in the header file and a global declaration of type OSBOOL to be generated in the C or C source file The mapping of ASN 1 declaration to global C or C value declaration is as follows ASN 1 production lt name gt BOOLEAN lt value gt 75 INTEGER Value Generated code OSBOOL lt name gt lt value gt INTEGER Value The INTEGER type causes a define statement to be generated in the header file of the form ASN1V_ lt valueName gt Where lt valueName gt would be replaced with the name in the ASN 1 source file The reason for doing this is the common use of INTEGER values for size and value range con straints in the ASN 1 specifications By generating define statements the symbolic names can be included in the source code making it easier to adjust the boundary values This mapping is defined as follows ASN 1 production lt name gt INTEGER lt value gt Generated code define ASN1V_ lt name gt lt value gt For example the following declaration ivalue INTEGER 5 will cause the following statement to be added to the generated header file define ASN1V_ivalue 5 The reason the asniv_ prefix is added is to prevent collisions with INTEGER value declarations and other declarat
100. type definition define T_MyType_alt 1 define T_MyType_alt_1l 2 typedef struct EXTERN MyType int t union re Aa OSINT32 alt a OR ae AY const OSUTF8CHAR alt_l u MyType Repeating Groups Repeating groups are specified in XML schema definitions using the minOccurs and maxOccurs facets on sequence or choice definitions These items are converted to ASN 1 SEQUENCE OF types An example of a repeating group is as follows lt xsd complexType name Names gt lt xsd sequence maxOccurs unbounded gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string gt lt xsd element name familyName type xsd string gt lt xsd sequence gt lt xsd complexType gt in this case ASNIC pulls the group out to form a type of form lt name gt element where lt name gt would be replaced with the complex type name In this case the name would be Names element A SEQUENCE OF type is then formed based on this newly formed type SEQUENCE OF Names element The generated C code corresponding to this is as follows typedef struct EXTERN Names_element const OSUTF8CHAR givenName const OSUTF8CHAR initial const OSUTF8CHAR familyName Names_element List of Names_element 101 Repeating Elements typedef OSRTDList Names This generated code is not identical to the code generated by performing an X 694 translatio
101. variable referenced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each generated PER decode function is as follows asnlPD_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows 194 Generated C Decode Method Format and Calling Parameters status asnlPD_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The pvalue argument is a pointer to a variable to hold the decoded result This variable is of the type generated from the ASN 1 production The decode function will automatically allocate dynamic memory for va
102. variables of gen erated types print This is the standard print option that causes print functions to be generated that output data to the standard output device stdout genPrtToStr This option causes print functions to be generated that write their output to a memory buffer genPrtToStrm This option causes print functions to be generated that write their output to an output stream via a user defined print callback function 240 Print to Standard Output Print to Standard Output The print option causes functions to be generated that print the contents of variables of generated types to the standard output device It is possible to specify the name of a c or cpp file as an argument to this option to specify the name of the file to which these functions will be written This is an optional argument If not specified the functions are written to separate files for each module in the source file The format of the name of each file is lt module gt Print c If an output filename is specified after the print qualifier all functions are written to that file The format of the name of each generated print function is as follows asnlPrint_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the l
103. was used the start address of the encoded message can be obtained by calling the rtX mlEncGetMsgPtr function Since the encoded XML message is nothing more than a null terminated string in a memory buffer the standard C library function strlen can be used to obtain the length A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC int main int argc char argv PersonnelRecord employee OSCTXT Ett OSOCTET msgbuf 4096 int stat Initialize context and set encode buffer pointer stat rtXmlInitContext amp ctxt if 0 stat printf context initialization failed n 230 Generated C Encode Method Format and Calling Parameters rtxErrPrint amp ctxt return stat rtXmlSetEncBufPtr amp ctxt msgbuf sizeof msgbuf Populate variable with data to be encoded mployee name givenName John Encode data stat XmlEnc_PersonnelRecord_PDU amp ctxt amp employee if stat 0 Note message can be treated as a null terminated string in memory printf encoded XML message n puts char msgbuf printf n else error processing rtFreeContext amp ctxt release the context pointer Generated C Encode Method Format and Calling Parameters When C code generation is specified using the xml switch the
104. where Name would be another type defined elsewhere within the module The compiler performs the substitution to create the proper C typedef for signedName typedef struct SignedName Name toBeSigned ASN1OBJID algorithmOID Params params ASN1DynBitStr signature SignedName When processing parameterized type definitions the compiler will first look to see if the param eters are actually used in the final generated code If not they will simply be discarded and the parameterized type converted to a normal type reference For example when used with informa tion objects parameterized types are frequently used to pass information object set definitions to impose table constraints on the final type Since table constraints do not affect the code that is generated by the compiler when table constraint code generation is not enabled the parameterized type definition is reduced to a normal type definition and references to it are handled in the same way as defined type references This can lead to a significant reduction in generated code in cases where a parameterized type is referenced over and over again For example consider the following often repeated pattern from the UMTS 3GPP specs ProtocolIE Field RANAP PROTOCOL IES IEsSetParam SEQUENCE id RANAP PROTOCOL IES amp id IEsSetParam criticality RANAP PROTOCOL IES amp criticality IEsSetParam id value RANAP
105. within constructors SEQUENCE SET CHOICE must begin with lowercase letters e Elements within constructors not properly delimited with commas either a comma is omitted at the end of an element declaration or an extra comma is added at the end of an element declaration before the closing brace e Invalid special characters only letters numbers and the hyphen character are allowed The use of the underscore character _ in identifiers is not allowed in ASN 1 but is allowed in C Since C does not allow hyphens in identifiers ASN1C converts all hyphens in an ASN 1 specification to underscore characters in the generated code Semantics errors occur on the compiler back end as the code is being generated In this case parsing was successful but the compiler does not know how to generate the code These errors are flagged by embedding error messages directly in the generated code The error messages always begin with an identifier with the prefix ASN so a search can be done for this string in order to find the locations of the errors A single error message is output to stderr after compilation on the unit is complete to indicate error conditions exist 42 ASN 1 To C C Mappings Type Mappings BOOLEAN The ASN 1 BOOLEAN type is converted into a C type named OSBOOL In the global include file osSysTypes h OSBOOL is defined to be an unsigned char ASN 1 production lt name gt BOOLEAN Generated C code
106. 1 SEQUENCE or SET value declaration to a global C or C value declaration is as follows ASN 1 production lt name gt lt SeqType gt lt value gt Generated code lt SeqType gt lt name gt The sequence value will be initialized in the value initialization function For example consider the following declaration SeqType SEQUENCE id INTEGER name VisibleString value SeqType id 12 name abc This would result in the following definition in the C or C source file SeqType value Code generated in value initialization function would be as follows 79 Constructed Type Values value id 12 value name abc SEQUENCE OF SET OF Value The mapping of an ASN 1 SEQUENCE OF or SET OF value declaration to a global C or C value declaration is as follows ASN 1 production lt name gt lt SeqOfType gt lt value gt Generated code lt SeqOfType gt lt name gt The sequence of value will be initialized in the value initialization function For example consider the following declaration SegOfType SEQUENCE OF SIZE 2 INTEGER value SeqOfType 1 2 This would result in the following definition in the C or C source file SegqOfType value Code generated in the value initialization function would be as follows value n 2 value element 0 1 value element 1 2
107. 1 to be generated to the given file name or to stdout if no filename was given Besides the obvi ous use of providing neatly formatted ASN 1 source code the tool is also useful for pro ducing ASN 1 source code from XML schema document XSD files as well as producing trimmed specifications when lt include gt or lt ex clude gt configuration directives are used asnstd x208 x680 mixed This option instructs the compiler to parse ASN 1 syntax conforming to the specified stan dard x680 the default refers to modern ASN 1 as specified in the ITU T X 680 X 690 series of standards x208 refers to the now dep recated X 208 and X 209 standards This syntax allowed the ANY construct as well as unnamed fields in SEQUENCE SET and CHOICE con structs This option also allows for parsing and generation of code for ROSE OPERATION and ERROR macros and SNMP OBJECTTYPE macros The mixed option is used to specify a source file that contains modules with both X 208 and X 680 based syntax attrs lt items gt This option only has meaning when generating an XML schema definitions XSD file using the xsd option It instructs the compiler to generate non native attributes for certain ASN 1 only items that can not be expressed in XSD The items are speci Running ASNIC from the Command line Option Argument Description fied as a comma delimited list Valid values for items ar
108. 2008 and 2010 project files the procedure to see the custom rule is very similar to that for Visual C 6 0 except that you choose Properties when you right click on the first ASN 1 file and then click on Custom Build Step or Custom Build Tool on the left w32 None This option is used with makefile and or Visual Studio project generation to indicate the gener ated file is to be used on a Windows 32 bit sys tem In the case of makefile generation this will cause a makefile to be generated taht si compat ible with the Visual Studio nmake utility 19 Using the GUI Wizard to Run ASN1IC Option Argument Description w64 warnings None None This option is similar to the w32 option docu mented above except that it specifies a Windows 64 bit system Output information on compiler generated warn ings Xer None This option instructs the compiler to generate functions that implement the XML Encoding Rules XER as specified in the X 693 ASN 1 standard xml None This option instructs the compiler to generate functions that encode decode data in an XML format that is more closely aligned with World Wide Web Consortium W3C XML schema The xsd option can be used in conjunction with this option to generate a schema describing the XML format xsd lt filename gt This option instructs the compiler to generate an equivalent XML Schema Defi
109. 8 will be used 121 122 Generated Encode Decode Function and Methods Encode Decode Function Prototypes If BER or DER encoding is specified a BER encode and decode function prototype is generated for each production DER uses the same form there are only minor differences between the two types of generated functions These prototypes are of the following general form int asnlE_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue ASNlTagType tagging int asnlD_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue ASN1TagType tagging int length The prototype with the asn E_ prefix is for encoding and the one with asn1D_ is for decoding The first parameter is a context variable used for reentrancy This allows the encoder decoder to keep track of what it is doing between function invocations The second parameter is for passing the actual data variable to be encoded or decoded This is a pointer to a variable of the generated type The third parameter specifies whether implicit or explicit tagging should be used In practically all cases users of the generated function should set this parameter to ASN EXPL explicit This tells the encoder to include an explicit tag around the encoded result The only time this would not be used is when the encoder or decoder is making internal calls to handle implicit tagging of elements The final parameter decode case only is length Thi
110. A A I oe La EmployeeNumber K ey KK KK A A A A A A A A A A A A A A A A A A A A I He define TV_EmployeeNumber TM_APPL TM_PRIM 2 typedef OSINT32 ASN1IT_EmployeeNumber class EXTERN ASN1C_EmployeeNumber public ASN1CType protected ASN1T_EmployeeNumber amp msgData public ASN1C_EmployeeNumber ASN1T_EmployeeNumber amp data ASN1C_EmployeeNumber ASN1MessageBufferIF amp msgBuf ASN1T_EmployeeNumber amp data standard encode decode methods defined in ASN1CType base class int Encode int Decode stream encode decode methods int EncodeTo ASN1MessageBufferIF amp msgBuf t DecodeFrom ASN1MessageBufferIF amp msgBuf EXTERN int asnlE_EmployeeNumber OSCTXT pctxt ASN1IT_EmployeeNumber pvalue ASN1TagType tagging EXTERN int asnlD_EmployeeNumber OSCTXT pctxt ASN1T_EmployeeNumber pvalue ASNiTagType tagging int length 112 Header h File Note the two main differences between this and the C version 1 The use of the ASN T_ prefix on the type definition The C version uses the ASN T_ prefix for the typedef and the ASN C_ prefix for the control class definition 2 The inclusion of the ASN1C_EmployeeNumber control class As of ASNIC version 5 6 control classes are not automatically generated for all ASN 1 types The only types they are generated
111. ASNIBERDecodeBuffer decodeBuffer msgbuf len ASN1T_PersonnelRecord employeeData ASN1C_PersonnelRecord employ decodeBuffer employeeData for 77 logic to read message into msgbuf 171 Generated C Decode Method Format and Calling Parameters status decodeBuffer ParseTagLen msgtag msglen if status 0 handle error Now switch on initial tag value to determine what type of message was received switch msgtag case TV_PersonnelRecord compiler generated constant if status employee Decod 0 decoding successful data in employeeData process received data else error processing break default handle unknown message type her switch Need to reinitialize objects for next iteration if isLastIteration employee memFreeAll end of loop This is quite similar to the first example Note that we have pulled the ASN T_Employee and ASNIC_Employee object creation logic out of the switch statement and moved it above the loop These objects can now be reused to process each received message The only other change was the call to employee memFreeAll that was added at the bottom of the loop Since we can t count on the objects being deleted to automatically release allocated memory we need to do it manually This call will free all memory held within the decoding context This will allow the
112. ASS s Val ueField or ValueSetField This type will appear as a defined type in the CLASS s ValueField or ValueSetField 92 Legacy Table Constraint Model This new type assignment is used for compiler internal code generation purpose It is not re quired for a user to understand this logic 3 Anew Value Assignment is created for a ValueField s default value definition as follows _ lt ClassName gt _ lt FieldName gt _default lt Type gt lt Value gt Here className is replaced with name of the Class Assignment and FieldName is replaced with name of this ValueField vaiue is the default value in the Class s ValueField and type is the type in Class s ValueField This value is used as a defined value in the information object definition for an absent value of the field This new value assignment is used for compiler internal code generation purpose It is not required for user to understand this logic ABSTRACT SYNTAX and TYPE IDENTIFIER The ASN 1 ABTRACT SYNTAX and TYPE IDENTIFIER classes are useful ASN 1 definitions These classes are described using the following ASN 1 definitions TYPE IDENTIFIER CLASS amp id OBJECT IDENTIFIER UNIQUE amp Type WITH SYNTAX amp Type IDENTIFIED BY amp id ABSTRACT SYNTAX CLASS amp id OBJEC IDENTIFIER UNIQUE amp Type amp property BIT STRING handles invalid encoding 0 DEFAULT WITH
113. BEGIN 134 General Procedure for Ta ble Constraint Encoding ATTRIBUTE CLASS amp Type amp id OBJECT IDENTIFIER UNIQUE WITH SYNTAX WITH SYNTAX amp Type ID amp id name ATTRIBUTE WITH SYNTAX VisibleString ID 011 name ATTRIBUTE WITH SYNTAX INTEGER ID iO Mahe o SupportedAttributes ATTRIBUTE name commonName Invoke SEQUENCE opcode ATTRIBUTE amp id SupportedAttributes argument ATTRIBUTE amp Type SupportedAttributes opcode END In the above example the Invoke type contains a table constraint Its element opcode refers to the ATTRIBUTE id field and argument element refers to the ATTRIBUTE Type field The opcode element is an index element for the Invoke type s table constraint The argument element is an open type whose type is determined by the opcode value In this example opcode is the key field The opcode element can have only two possible values 0 1 1 or 01 2 If the opcode value is 0 1 1 then argument will have a VisibleString value and if the opcode value is 0 1 2 then argument will have an INTEGER value Any other value of the opcode element will be violation of the Table Constraint If the SupportedAttributes information object set was extensible indicated by a at the end of the definition then the argument element may have a value o
114. C like brace format As of re lease version 6 0 bractext is the default details was the default or only option in previous ver sions shortnames None Generate a shorter form of an element name for a deeply nested production By default all inter mediate names are used to form names for ele ments in nested types This can lead to very long names for deeply nested types This option caus es only the production name and the last element name to be used to form a generated type name static None This has the same effect as specifying the glob al lt storage gt static lt storage gt configuration item The compiler will insert static elements instead of pointer variables in some generated structures stream None This option instructs the compiler to gener ate stream based encoders decoders instead of memory buffer based This makes it possible to encode directly to or decode directly from a source or sink such as a file or socket In the case of BER it will also cause forward encoders to be generated which will use indefinite lengths for all constructed elements in a message 17 Running ASNIC from the Command line Option Argument Description Note that stream and memory buffer based en code decode functions cannot be used combined in any way The two are mutually exclusive If the stream option is selected then only stream based run time functions can be used wi
115. CE local INTEGER global OBJECT IDENTIFIER amp ArgumentType amp ResultType amp Errors ERROR OPTIONAL Users familiar with ASN 1 will recognize this as a simplified definition of the ROSE OPERATION MACRO using the Information Object format When a class specification such as this is parsed information on its fields is maintained in memory for later reference In the simple form of code generation the class definition itself does not result in the generation of any corresponding C or C code It is only an abstract template that will be used to define new items later on in the specification In the table form if C is specified an abstract base class is generated off of which other classes are derived for information object specifications Fields from within the class can be referenced in standard ASN 1 types It is these types of ref erences that the compiler is mainly concerned with These are typically header types that are used to add a common header to a variety of other message body types An example would be the following ASN 1 type definition for a ROSE invoke message header Invoke SEQUENCE invokeID INTEGER opcode OPERATION operationCode argument OPERATION amp ArgumentType This is a very simple case that purposely omits a lot of additional information such as Information Object Set constraints that are typically a part of definitions such as this The reason thi
116. Calling C Decode Functions This section describes the step by step procedure for calling a C PER decode function This method must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done Unlike BER the user must know the ASN 1 type of a PER message before it can be decoded This is because the type cannot be determined at run time There are no embedded tag values to reference to determine the type of message received 195 Procedure for Calling C Decode Functions The following are the basic steps in calling a compiler generated decode function 1 Prepare a context variable for decoding 2 Initialize the data structure to receive the decoded data 3 Call the appropriate compiler generated decode function to decode the message 4 Free the context after use of the decoded data is complete to free allocated memory structures Before a PER decode function can be called the user must first initialize a context block structure The context block is initialized by either calling the rtNewContext function to allocate a dynamic context block or by calling rt nitContext to initialize a static block The pu_setBuffer function must then be called to specify a message buffer that contains the PER encoded message to be decoded This function also allows for the specification of aligned or unaligned decoding The variable that is to receive the d
117. DTC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue int asnlPETC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue int asnlPDTC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue The purpose of these functions is to verify the fixed values within the table constraints are what they should be and to encode or decode the open type fields using the encoder or decoder assigned to the given table row Calls to these functions are automatically built into the standard encode or decode functions for the given type They should be considered hidden functions not for use within an application that uses the API C Code Generation For C code is generated for ASN 1 classes information objects and information object sets This code is then referenced when table constraint processing must be performed Each of the generated C classes builds on each other First the classes generated that correspond to ASN 1 CLASS definitions form the base class foundation Then C classes derived from these base classes corresponding to the information objects are generated Finally C singleton classes corresponding to the information object sets are generated Each of these classes provides a con tainer for a collection of C objects that make up the object set Additional encode and decode functions are also generated as they were in the C code generation case for interfacing with the object definitions abov
118. ER and then later decide to use the Packed Encoding Rules PER it should only be a simple matter of changing a few function calls to accomplish the change Procedures for such things as populating data for encoding accessing decoded data and dynamic memory management are the same for all of the different encoding rules This section describes common procedures for encoding or decoding data that are applicable to any of the different encoding rules Subsequent sections will then describe what will change for the different rules Dynamic Memory Management The ASNIC run time uses specialized dynamic memory functions to improve the performance of the encoder decoder It is imperative to understand how these functions work in order to avoid memory problems in compiled applications ASNIC also provides the capability to plug in a dif ferent memory management scheme at two different levels the high level API called by the gen erated code and the low level API that provides the core memory managment functionality The ASNIC Default Memory Manager The default ASN1C run time memory manager uses an algorithm called the nibble allocation al gorithm Large blocks of memory are allocated up front and then split up to provide memory for smaller allocation requests This reduces the number of calls required to the C malloc and free functions These functions are very expensive in terms of performance The large blocks of memory are tracked through the A
119. ER encode buffer object ASN XEREncode Buffer to describe the buffer into which the message will be encoded Constructors are available that allow a static message buffer to be specified and or canonical encoding to be turned on canonical encoding removes all encoding options from the final message to produce a single encoded representation of the data The default constructor specifies use of a dynamic encode buffer and canonical encoding set to off Instantiate an ASNIT_ lt type gt object and populate it with data to be encoded Instantiate an ASN1C_ lt type gt object to associate the message buffer with the data to be encod ed Invoke the ASN1C_ lt type gt object Encode method Check the return status The return value is a status value indicating whether encoding was successful or not Zero indicates success If encoding failed the status value will be a negative number The encode buffer method printErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred If encoding was successful get the start of message pointer and message length The start of message pointer is obtained by calling the getMsgPtr method of the encode buffer object If static encoding was specified i e a message buffer address and size were specified to the XER Encode Buffer class constructor the start of message pointer is the buffer start address The message length is obtained by calling the getMsgLen
120. EXTERN ASNIC_A OSRTMessageBufferIF amp msgBuf EXTERN ASNIC_A OSRTContext amp context 119 Generated Build Files standard encode decode methods defined in ASN1CType base class int Encode int Decode stream encode decode methods EXTERN int EncodeTo OSRTMessageBufferIF amp msgBuf EXTERN int DecodeFrom OSRTMessageBufferIF amp msgBuf bi Note the use of ExTERN in the generated code it prefixes the constructors and the encoding and decoding functions but not the class declaration These prefixes are repeated in the implementation EXTERN ASN1C_A ASN1C_A ASN1CType Users should not have to modify generated code for use on the Symbian platform but should be aware of these particular differences when writing Symbian applications Generated Build Files Generated Makefile The genmake option causes a portable makefile to be generated to assist in the C or C compi lation of all of the generated C or C source files This makefile contains a rule to invoke ASN1C to regenerate the c and h files if any of the dependent ASN 1 source files are modified It also contains rules to compile all of the C or C source files Header file dependencies are generated for all the C or C source files Two basic types of makefiles are generated 1 A GNU compatible makefile This makefile is compatib
121. Generated Test Functions The genTest option causes test functions to be generated These functions can be used to populate variables of generated types with random test data The main purpose is to provide a code template to users for writing code to populate variables This is quite useful to users because generated data types can become very complex as the ASN 1 schemas become more complex It is sometimes difficult to figure out how to navigate all of the lists and pointers Using genTest can provide code that simply has to be modified to accomplish the population of a data variable with any type of data The generated test functions are written to a c or cpp file with a name of the following format lt asnlModuleName gt Test c where lt asnIModuleName gt is the name of the ASN 1 module that contains the type definitions The format of the name of each generated test function is as follows asnlTest_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each generated test function is as follows lt typeName gt pvalue lt testFunc gt
122. IMPLICIT SEQUENCE identification CHOICE syntaxes SEQUENCE abstract OBJECT IDENTIFIER transfer OBJECT IDENTIFIER syntax OBJECT IDENTIFIER presentation context id INTEGER context negotiation SEQUENCE presentation context id INTE transfer syntax OBJECT IDENTIFIER Q R transfer syntax OBJECT IDENTIFIER fixed NULL data value descriptor ObjectDescriptor OPTIONAL data value OCTET STRING WITH COMPONENTS data value descriptor ABSENT The ASNIC compiler is used to create a meta definition for this structure This code will be always generated in the AsniEmbeddedPDV h and AsnlEmbeddedPDV c cpp files The code will only be gen erated if the given ASN 1 source specification requires this definition The resulting C structure is populated just like any other compiler generated structure for working with ASN 1 data Note NOTE It is recommended that if a specification contains multiple ASN 1 source files that reference EMBEDDEDPDYV all of these source files be compiled with a single ASNIC call in order to ensure that only a singled copy of the AsnlEmbeddedPDV source files are generated Parameterized Types The ASNIC compiler can parse parameterized type definitions and references as specified in the X 683 standard These types allow dummy parameters to be
123. ITU T international standards X 680 through X 683 ISO IEC 8824 It generates code for encoding decoding data in accordance with the fol lowing encoding rules e Basic Encoding Rules BER Distinguished Encoding Rules DER or Canonical Encoding Rules CER as published in the ITU T X 690 and ISO IEC 8825 1 standards e Packed Encoding Rules PER as published in the ITU T X 691 and ISO IEC 8825 2 standards Both aligned and unaligned variants are supported via a switch that is set at run time e XML Encoding Rules XER as published in the ITU T X 693 and ISO IEC 8825 3 standards e Medical Device Encoding Rules MDER as published in the ISO TEEE 11073 standards e Octet Encoding Rules OER as published in the NTCIP 1102 2004 standard Additional support for XML is provided in the form of an option to generate an equivalent XML Schema Definitions XSD file for a given ASN 1 specification Encoders and decoders can then be generated using the xml option to format or parse XML documents that conform to this schema This level of support is closer to the W3C definition of XML then is the ITU T X 693 XER defi nition As of release version 6 0 it is possible to compile an XML schema definitions XSD file and generate encoders decoders that can generate XML in compliance with the schema as well as binary encoders encoders that implement the ASN 1 binary encoding rules The compiler is capable of parsing all ASN 1 syntax as defined in the
124. J OK Rk I ok define TV_EmployeeNumber TM_APPL TM_PRIM 2 typedef OSINT32 EmployeeNumber EXTERN int asnlE_EmployeeNumber OSCTXT pctxt EmployeeNumber pvalue ASNiTagType tagging EXTERN int asnlD_EmployeeNumber OSCTXT pctxt EmployeeNumber pvalue ASNiTagType tagging int length This corresponds to the following ASN 1 production specification 111 Header h File EmployeeNumber APPLICATION 2 IMPLICIT INTEGER In this definition 7V_EmployeeNumber is the tag constant Doing a logical OR on the class form and identifier fields forms this constant This constant can be used in a comparison operation with a tag parsed from a message The following line typedef OSINT32 EmployeeNumber declares EmployeeNumber to be of an integer type note OSINT32 and other primitive type def initions can be found in the osSysTypes h header file asnlE_EmployeeNumber and asnID_EmployeeNumber are function prototypes for the encode and decode functions respectively These are BER function prototypes If the per switch is used PER function prototypes are generated The PER prototypes begin with the prefix asn PE_ and asn PD_ for encoder and decoder respectively XER function prototypes begin with asn XE_ and asnlXD_ A sample section from a C header file for the same production is as follows KK KK A A A A A A A A A A A A A A A A A A
125. Jnit switch can be used to turn initialization function generation off The use of initialization functions are optional a variable can be initialized by simply setting its contents to zero for example by using the C run time memset function The advantage of initial ization function is that they provide smarter initialization which can lead to improved application performance For example it is not necessary to set a large byte array to zero prior to its receiving a populated value The use of memset in this situation can result in degraded performance Generated initialization functions are written to the main lt module gt c file This file contains com mon constants global variables and functions that are generic to all type of encode decode func tions If the cfile command line option is used the functions are written to the specified c or cpp file along with all other generated functions If maxcfiles is specified each generated initialization function is written to a separate c file The format of the name of each generated initialization function is as follows asnliInit_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be appl
126. L aligned TRUE step 1 instantiate a PER decode buffer object ASNIPERDecodeBuffer decodeBuffer msgbuf msglen step 2 instantiate an ASN1T_ lt ProdName gt object ASN1T_PersonnelRecord msgData step 3 instantiate an ASN1C_ lt ProdName gt object d by ASNIC aligned ASN1C_PersonnelRecord employ decodeBuffer msgData loop to continuously decode records for logic to read message into msgbuf stat employee Decod j3 step 5 check the return status if stat 0 process received data else error processing decodeBuffer PrintErrorInfo step 6 free dynamic memory mployee memFreeAll If reading unaligned data it is necessary to do a byte align operation to move 199 Performance Considerations Dy namic Memory Management to the next octet boundary before decoding the next message decodeBuffer byteAlign The only difference between this and the previous example is the addition of the decoding loop and the modification of step 6 in the procedure The decoding loop is an infinite loop to continuously read and decode messages from some interface such as a network socket The decode calls are the same but before in step 6 we were counting on the message buffer and control objects to go out of scope to cause the memory to be released Since the objects are now being reused this will not happen
127. NIVERSAL 20 IMPLICIT OCTET STRING VideotexString tis UNIVERSAL 21 IMPLICIT OCTET STRING TA5String ei UNIVERSAL 22 IMPLICIT OCTET STRING UTCTime UNIVERSAL 23 IMPLICIT GeneralizedTim GeneralizedTim UNIVERSAL 24 IMPLICIT IA5String GraphicString UNIVERSAL 25 IMPLICIT OCTET STRING VisibleString UNIVERSAL 26 IMPLICIT OCTET STRING GeneralString UNIVERSAL 27 IMPLICIT OCTET STRING UniversalString 225 UNIVERSAL 28 IMPLICIT OCTET STRING BMPString r UNIVERSAL 30 IMPLICIT OCTET STRING ObjectDescriptor UNIVERSAL 7 IMPLICIT GraphicString Of these all are represented by const char pointers except for the BMPString UniversalString and UTF8String types 70 Time String Types The BMPString type is a 16 bit character string for which the following structure is used typedef struct OSUINT32 nchars OSUNICHAR data Asn1l1l6BitCharString The osunrcuar type used in this definition represents a Unicode character UTF 16 and is defined to be aC unsigned short type See the rtBMPTocString rtBMPToNewCString and the rtcToBMPstring run time function descrip tions for information on utilities that can convert standard C strings to and from BMP string format The universalString type is a 32 bit character string for which the following structure is used typedef struct OSUINT32 nchars OS32BITCHAR data Asn1l32BitCharString The os32B1TcHar type used in this definition is defined to be a C unsigned int type S
128. QUENCE OSINT32 invokeID OPERATION_operationCode opcode ASN10OpenType argument The following would be the procedure to add the Invoke header type to an ASN 1 message body 1 Encode the body type 2 Get the message pointer and length of the encoded body 3 Plug the pointer and length into the numocts and data items of the argument open type field in the Invoke type variable 4 Populate the remaining Invoke type fields 5 Encode the Invoke type to produce the final message In this case the amount of code generated to support the information object references is minimal The amount of coding required by a user to encode or decode the variable type field elements however can be rather large This is a tradeoff that exists between using the compiler generated table constraints solution as we will see below and using the simple form Unions Table Form Code Generation If we now add table constraints to our original type definition it might look as follows Invoke SEQUENCE invokeID INTEGER opcode OPERATION amp o0perationCode My ops argument OPERATION amp ArgumentType My ops opcode The My ops constraint on the opcode element specifies an information object set that con strains the element value to one of the values in the object set The My ops opcode constraint 129 Unions Table Form Code Generation on the argument element goes a
129. R gt 1 lt INTEGER gt lt INTEGER gt 2 lt INTEGER gt lt INTEGER gt 3 lt INTEGER gt lt A gt in XML it would be the following lt A gt 1 2 3 lt A gt e The values of the BOOLEAN data type are expressed as the lower case words true or false with no delimiters In XER the values are lt TRUE gt and lt FALSE gt e Enumerated token values are expressed as the identifiers themselves instead of as empty XML elements i e elements wrapped in lt gt For example a value of the ASN 1 type Colors ENUMERATED red blue green equal to red would simply be lt color gt red lt color gt instead of lt color gt lt red gt lt color gt e The special REAL values lt PLUS INFINITY gt and lt MINUS INFINITY gt are represented as INF and INF respectively e GeneralizedTime and UTCTime values are transformed into the XSD representation for date Time YY YY MMDDTHH MM SS SSSS Zl l HH MM when encoded to XML When an XML document is decoded the time format is transformed into the ASN 1 format Also if code is generated by compiling XML schema specifications the generated XML will con tain features defined in the schema which cannot be specified using plain ASN 1 such as attributes and namespaces Note that it is possible to support these items if ASN 1 with Extended XER no tation E XER is used but this is not supported by ASNIC Its method of supporting these con structs
130. RAG Fragment decode success status This is returned when decoding is successful but only a fragment of the item was decoded User should repeat the decode operation in order to fully decode mes sage 100 ASN_E_BASE Error base ASN 1 specific errors start at this base number to distinguish them from common and other error types ASN_E_BASE ASN_E_INVOBJID Invalid object identifier This error code is re turned when an object identifier is encountered that is not valid Possible reasons for being in valid include invalid first and second arc identi fiers first must be 0 1 or 2 second must be less than 40 not enough subidentifier values must be 2 or more or too many arc values maximum number is 128 ASN_E_BASE 1 ASN_E_INVLEN Invalid length This error code is returned when a length value is parsed that is not consistent with 277 ASN 1 specific Status Messages Error Code Error Name Description other lengths in a BER or DER message This typically happens when an inner length within a constructed type is larger than the outer length value ASN_E_BASE 2 ASN_E_BADTAG Bad tag value This error code is returned when a tag value is parsed with an identifier code that is too large to fit in a 32 bit integer variable ASN_E_BASE 3 ASN_E_INVBINS Invalid binary string This error code is returned when decoding XER data and a bit string value is
131. RATED etc It is passed using a pointer reference if it is a structured ASN 1 type value in this case the name will be pvalue instead of value Check the generated function prototype in the header file to determine how this argument is to be passed for a given function The elemName and nsPrefix arguments are used to pass the XML element name and namespace prefix respectively The two arguments are combined to form a qualified name QName of the form lt nsPrefix elemName gt If elemName is null or empty then no element tag is added to the encoded content If nsPrefix is null or empty the element name is applied as a local name only without a prefix The function result variable stat returns the status of the encode operation Status code zero indi cates the function was successful A negative value indicates encoding failed Return status values 229 Procedure for Calling C Encode Functions are defined in the rtxErrCodes h include file The error text and a stack trace can be displayed using the rtxErrPrint function In addition to the XML encode function generated for types a different type of encode function is generated for Protocol Data Units PDU s These are types in an ASN 1 specification that are not referenced by any other types In an XML schema specification these are global elements that are not reference within any other types or global elements The format of the a PDU encode function is the same name format
132. RlrqApdu 208 Encoding a Series of Messages Using the C Encode Functions data u rlrq gt reason normal Step 3 Call the generated encode function stat mderEnc_ApduType amp ctxt amp data Step 4 Check the return status if stat lt 0 rtxErrPrint amp ctxt retur Stary stat rtFreeContext amp ctxt if stat 0 printf Error freeing context n return stat return 0 Encoding a Series of Messages Using the C Encode Functions Encoding a series of messages in MDER is very similar to encoding a series of messages in any other set of encoding rules Performance can be improved by calling rt xMemReset to avoid allocat ing new memory for dynamic message structures as in the code below initialize context et c for 7 initialize populate message structure to b ncoded call mderEnc_ lt messageType gt call rtxMemReset when finished encoding rtxMemReset pctxt More details may be found in the sample programs included in the ASNIC software development kit Generated MDER Decode Functions Generated C Function Format and Calling Pa rameters The format of the name of each decode function generated is as follows mderDec_ lt prefix gt lt prodName gt 209 Procedure for Calling C Decode Functions where lt prodName gt is the name of the ASN 1 production for which the function
133. SN 1 context block OSCTXT structure For C this means that an initialized context block is required for all memory allocations and deal locations All allocations are done using this block as an argument to routines such as rtxMemaAlloc All memory can be released at once when a user is done with a structure containing dynamic mem ory items by calling rtxMemFree Other functions are available for doing other dynamic memory operations as well See the C C Run time Reference Manual for details on these High Level Memory Management API 140 Dynamic Memory Management The high level memory management API consists of C macros and functions called in gemerated code and or in application programs to allocate and free memory within the ASNIC run time At the top level are a set of macro definitions that begin with the prefix rtxMem These are mapped to a set of similar functions that begin with the prefix rt MemHeap A table showing this basic mapping is as follows Macro Function Description rtxMemAlloc rtxMemHeapAlloc Allocate memory rtxMemAllocz rtxMemHeapAllocz Allocate and zero memory rtxMemRealloc rtxMemHeapRealloc Reallocate memory rtxMemF ree rtxMemHeapFreeAll Free all memory in context rtxMemFreePtr rtxMemHeapFreePtr Free a specific memory block See the ASNIC C C Common Runtime Reference Manual for further details on these functions and macros It is possible to rep
134. Therefore there is no need to allocate memory for the data and then copy the data from the buffer into the allocated memory structure As an example of what fast copy does consider a simple ASN 1 SEQUENCE consisting of an element a an INTEGER and b an OCTET STRING Simple SEQUENCE a INTEGER b OCTET STRING Assume an encoded value of this type contains a value of a 123 hex 7B and b contains the hex octets 0x01 0x02 0x03 The generated variable for the OCTET STRING will contain a data pointer So rather than allocate memory for this string and copy the data to it fast copy will simply store a pointer directly to the data in the buffer Simple a 123 Simple b numocts 3 Simple b data ptr Message buffer A or m ofofo fo os The pointer stored in the data structure points directly at data in the message buffer No memory allocation or copy is done 175 Using Initialization Functions The user must keep in mind that if this technique is used the message buffer containing the decoded message must be available as long as the type variable containing the decoded data is in use This will not work in a producer consumer threading model where one thread is decoding messages and the next thread is processing the contents The producer thread will overwrite the buffer contents and therefore data referenced in the decoded message type variable that the consumer is proc
135. XSD element with minmaxOc curs gt 1 and more instances of the element are received the content model group RTERR_INVOPT Invalid option in choice This status code is re turned when encoding or decoding an ASN 1 CHOICE or XSD xsd choice construct When encoding it occurs when a value in the generated t member variable is outside the range of index es of items in the content model group It occurs on the decode side when an element is received that is not defined in the content model group 10 RTERR_NOMEM No dynamic memory available This status code is returned when a dynamic memory allocation request is made and an insufficient amount of memory is available to satisfy the request 11 RTERR_INVHEXS Invalid hexadecimal string This status code is returned when decoding a hexadecimal string value and a character is encountered in the string that is not in the valid hexadecimal character set 0 9A Fa f or whitespace 12 RTERR_INVREAL Invalid real number value This status code is re turned when decoding a numeric floating point value and an invalid character is received i e not numeric decimal point plus or minus sign or exponent character 13 RTERR_STROVFLW String overflow This status code is returned when a fixed sized field is being decoded as specified by a size constraint and the item con tains more characters or bytes then this amount It can occur when a run
136. ader After initializing the context and populating a variable of the structure to be encoded a decode function can be called to decode a message from the stream If the return status indicates success the C variable that was passed as an argument will contain the decoded message contents Note that the decoder may have allocated dynamic memory and stored pointers to objects in the C structure After processing on the C structure is complete the run time library function rxMemFree should be called to free the allocated memory After stream processing is complete the stream is closed by invoking the rtxStreamClose function A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC 179 Generated Streaming C Function Format and Calling Parameters include rtxsrc rtxStreamFile h main ASNITAG msgtag int msglen OSCTXT ctxt PersonnelRecord employee const char filename message dat Step 1 Initialize a context variable for decoding if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 Step 2 Open the input stream to read data stat rtxStreamFileCreateReader amp ctxt filename if stat 0 rtxErrPrint amp ctxt return stat Step 3 Test messag
137. aeenas 239 Generated Memory Free Functions sic iiss iessiecseckedisievecatayesaceededeccsansavastiseevacegavaccetaee dvecteaye 239 Generated Print PUNCHONS 224 2 i riaeh didi usta iaedaut adden ative eden ees 240 Print to Standard Output sssrinin oett a E aE RR ERE 241 Print to Sting esenee a E eased ee E ARS 241 Print to Stream hacia tiveteetitenek tee ee Ne E aE ee RG eed SAA ede 242 Print Format sonnantes aiiai a EEE EEEE S EAE 243 Generated Compare PuncttOns cijssacdviveccceisagesssaasanseessaseaedaawasaasaceaenesassascenele dees teasssnereunieoans 244 vi ASNIC Generated Copy Functions ayiccsisisvssactasascevashcesqstswesdecainteaeds sue EE TEE S N Eaa asdar ebesi 245 Generated Fest F nctionS seie eesin ee E E E E e A SEES 248 Event Handler Interface soisessa sE E a EE EEEE Ea tni 251 How it Works ccvsshcceiecesntanwassbentsud sina shdvg sandy cd E E EE E T EE A aT 251 How 00 Use It creana tigrene A E E E R RS 253 IMPORT EXPORT Of Types essrsnnsorinuii naina te e E RE 259 ROSE and SNMP Macro Support sssssseesssseesseessesssesssseesseesseesseeesetesseeesseesseesseessseeesseesseesseesset 261 ROSE OPERATION and ERROR eseseseseesseossessesseessessesseessessosseesseesosseesseosoesoesseosseseessee 261 SNMP OBJECT TYPE oaae a a a E EE E RE E A A 264 Az Runtime Status CodeScssiini stes iin i E A O AEA ads aaa ads 267 ASNIG Brror Messages riniorrer iracas e ian E E E E TAA 267 General Status Messages s cccaissageanitubeteecisaav
138. age buffers that can be described 1 static this is a fixed size byte array into which the message is encoded 2 dynamic in this case the encoder manages the allocation of memory to hold the encoded mes sage 3 stream in this case the encoder writes the encoded data directly to an output stream 146 Accessing Encoded Message Components The static buffer case is generally the better performing case because no dynamic memory alloca tions are required However the user must know in advance the amount of memory that will be required to hold an encoded message There is no fixed formula to determine this number ASN 1 encoding involves the possible additions of tags and lengths and other decorations to the provided data that will increase the size beyond the initial size of the populated data structures The way to find out is either by trial and error an error will be signaled if the provided buffer is not large enough or by using a very large buffer in comparison to the size of the data In the dynamic case the buffer description passed into the encoder is a null buffer pointer and zero size This tells the encoder that it is to allocate memory for the message It does this by allocating an initial amount of memory and when this is used up it expands the buffer by reallocating This can be an expensive operation in terms of performance especially if a large number of reallocations are required For this reason run time helpe
139. allback myCallback void pStrmInfo For registering a context level callback use rtxSetPrintStream OSCTXT pctxt rtxPrintCallback myCallback void pStrmInfo Once the callback function is registered the calling of each generated print to stream function will result in output being directed to the callback function The print to stream functions are declared as follows asnlPrtToStrm_ lt name gt OSCTXT pctxt const char name lt name gt pvalue The name and pvalue arguments are the same as they were in the print case The pctxt argument is used to specify an ASN1C context If a valid context argument is passed and there is a context level callback registered then that callback will be used If there is no context level callback registered or the pctxt argument is NULL then the global callback will be used If there is no global callback registered the default callback will be used which writes the print output to stdout If C code generation is specified setPrintStream and toStream methods are added to the ASN1C control class for the type The setPrintStream method takes only myCallback and pStrmInfo argu ments the pctxt argument is obtained from the context pointer reference contained within the class The toStream method takes only a name argument the pctxt argument is derived from the context pointer reference within the class and the pvalue argument is obtained from the msgData reference contained within the class
140. allei eii i a E E AE E R E 75 INTEGER Valei a ae dite ier A e aes ie aa 76 REAL Valts enoei e e e i a ace a Ree 76 Enumerated Value Specification snsc aasa ganas 77 Binary and Hexadecimal String Valley oi 230 tes ee ctl oes 77 Character Sting Value sisse e aa ed teh Eten eee oe eee 11 iii ASNIC Object Identifier Value Specification cs siccssesiisecaciapeavecsasesesessavessesssedeestanvavectensdaeesanvees 78 Constructed Type Values ensisi devedecanecesangis E E EEEa 78 Table Constraint Related Structures s sc ciasncckavsseveustavsevaedishgvessnaydeaedadesceeeaseacbatacbecnctessavens 81 Unions Table Constraint Model ccccscccissscccsascvjeacases se ceeiuscdaasgsdetaacsdua scars sdevecseadsdcacsuaas 81 Legacy Table Constraint Model scccssccievsicisccccasstsversadvesacetiesenenavaeaanasevssesnssndaentedersteaye 87 XSD TO C E TY PE MAPPINGS nirna a a alee et and a G 97 XSD Simple Types soscsacissnvcatasvecadeeavataeds neS A EE E E EEE AEA A REE AEE 97 ASD Complex Types sisenenud eian a E E E ERE 98 RSCUSSQUEMC dirien ea TE E EE E RT A A EA tens denelles 98 KSC AID nnua oa R EE E E E E R R E S 99 sd choice and ASAUMION 5 sdssksessigecssecgsndvedsaressuedsseaenessspapacde e E asii E ia a aSk 100 R p ating GTO pS aces sa5eceisdseaassevsbancssuptaa es eira E E EE AE RE E RE aai 101 Repeating Elements rsio trenerio ar i EE E AE A E E 102 KSA list ein ip a a E E A A T E ATE 102 RSCIAIY Apasesdiasiedevisyaveldesaeeracasanv
141. allows any of a set of elements defined to be in the group to be used in the place of the base element A simple example of this is as follows lt xsd element name MyElement type MyType gt lt xsd complexType name MyType gt lt xsd sequence gt lt xsd element ref MyBaseElement gt lt xsd sequence gt lt xsd complexType gt lt xsd element name MyBaseElement type xsd string gt lt xsd element name MyExtendedElement type xsd string substitutionGroup MyBaseElement gt In this case the global element myElement references myType which is defined as a sequence with a single element reference to MyBaseElement MyBaseElement is the head element in a substitution group that also includes myExt endedElement This means MyType can either reference MyBaseElement Or MyExtendedElement As per X 694 ASNIC generates a special type that acts as a container for all the different possi ble elements in the substitution group This is a choice type with the name lt BaseElement gt _group where lt BaseElement gt would be replaced with the name of the subsitution group head element my BaseElement in this case The generated C type definitions for the above XSD definitions follow typedef const OSUTF8CHAR MyBaseElement typedef const OSUTF8CHAR MyExtendedElement define T_MyBaseE define T_MyBaseE lement_group_myBaseElement 1 lement_group_myExtendedElement 2
142. alue to determine what type of message was received switch msgtag case TV_PersonnelRecord compiler generated constant in gt gt employee if in getStatus 0 printf decode of PersonnelRecord failed n in printErrorInfo return 1 or employee DecodeFrom in case TV_ handle other known messages Need to reinitialize objects for next iteration mployee memFreeAll end of loop return 0 This is quite similar to the first example Note that we have pulled the ASN T_Employee and ASN1IC_Employee object creation logic out of the switch statement and moved it above the loop These objects can now be reused to process each received message 185 Generated Streaming C Decode Method Format and Calling Parameters The only other change was the call to employee memFreeAll that was added at the bottom of the loop Since the objects are not deleted to automatically release allocated memory we need to do it manually This call will free all memory held within the decoding context This will allow the loop to start again with no outstanding memory allocations for the next pass 186 Generated PER Functions Generated PER Encode Functions PER encode decode functions are generated when the per switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C PER encode function is generated This function
143. ample decoding of the element id is deferred Identifier SEQUENCE id INTEGER oid OBJECT IDENTIFIER The following configuration file is required to indicate the element id is to be processed as an open type i e that it will be decoded later lt asnlconfig gt lt module gt lt name gt modulename lt name gt lt production gt lt name gt Identifier lt name gt lt element gt lt name gt id lt name gt lt isOpenType gt lt element gt lt production gt lt module gt lt asnlconfig gt In the generated code the element id type will be replaced with an open type Asn OpenType for C or AsnITOpenType for C and the following additional function is generated EXTERN int asnlD_Identifier_id_OpenType OSCTXT pctxt OSINT32 pvalue In the Identifier decode function element id is decoded as an open type Generated BER Streaming Decode Functions BER messages can be directly read and decoded from an input stream such as a file network or memory stream using BER streaming decode functions The ASN1C compiler stream option is used to generate decoders of this type For each ASN 1 production defined in an ASN 1 source file a C streaming decode function is generated This function will decode an ASN 1 message into a C variable of the given type If C code generation is specified a control class is generated that contains a DecodeFrom method that wr
144. ample of an information object set that uses the information object class defined above is as follows SupportedAttributes ATTRIBUTE name commonName This results in the generation of the following C class class EXTERN SupportedAttributes protected ATTRIBUTE mObjectSet 2 const size_t mNumObjects static SupportedAttributes mpInstance SupportedAttributes OSCTXT pctxt public ATTRIBUTE lookupObject ASN1TObjJId _id static SupportedAttributes instance OSCTXT pctxt The mobject Set array is the container for the information object classes These objects are created and this array populated in the class constructor Note that this is a singleton class as evidenced by the protected constructor and instance methods Therefore the object set array is only initialized once the first time the instance method is invoked The other method of interest is the lookupobject method This was generated for the id field be cause it was identified as a key field This determination was made because ia was declared to be UNIQUE in the class definition above A field can also be determined to be a key field if it is referenced via the e notation in a table constraint in a standard type definition For example in the following element assignment argument OPERATION amp Type SupportedAttributes opcode the opcode element s ATTRIBUTE class field is identified as a key field 96 XSD TO C
145. an existing stream is open in the context The ex isting stream must first be closed before initial izaing a stream for a new operation 47 RTERR_NULLPTR Null pointer This status code is returned when a null pointer is encountered in a place where it is expected that the pointer value is to be set 48 RTERR_FAILED General failure Low level call returned error 49 RTERR_ATTRFIXEDVAL Attribute fixed value mismatch The attribute contained a value that was different than the fixed value defined in the schema for the at tribute 50 RTERR_MULTIPLE Multiple errors occurred during an encode or de code operation See the error list within the con text structure for a full list of all errors 51 RTERR_NOTYPEINFO This error is returned when decoding a derived type definition and no information exists as to what type of data is in the element content When decoding XML this normally means that an xsi type attribute was not found identifying the type of content 52 RTERR_ADDRINUSE Address already in use This status code is re turned when an attempt is made to bind a socket to an address that is already in use 53 RTERR_CONNRESET Remote connection was reset This status code is returned when the connection is reset by the remote host via explicit command or a crash 54 RTERR_UNREACHABLE Network failure This status code is returned when the network or host
146. and message buffer objects go out of scope For example consider the following code fragment ASN1T_ lt type gt func2 ASNIT_ lt type gt p new ASNIT_ lt type gt ASNIBERDecodeBuffer decbuf ASN1C_ lt type gt cc decbuf p cc Decode After return cc and decbuf go out of scope therefore all memory allocated within struct p is released return p void funcl ASN1T_ lt type gt pType func2 pType is not usable at this point because dynamic memory has been released As can be seen from this example once func exits all memory that was allocated by the decode function will be released Therefore any items that require dynamic memory within the data vari able will be in an undefined state An exception to this rule occurs when the type of the message being decoded is a Protocol Data Unit PDU These are the main message types in a specification The ASN1C compiler designates types that are not referenced by any other types as PDU types This behavior can be overridden by using the pdu command line argument or lt isPDU gt configuration file element The significance of PDU types is that generated classes for these types are derived from the ASNITPDU base class This class holds a reference to a context object The context object is set by Decode and copy methods Thus even if control class and message buffer objects go out of scope the memory will not be freed until t
147. ant is generated for each of these values The format of this constant is 65 CHOICE T_ lt name gt _ lt element name gt where lt name gt is the name of the ASN 1 production and lt element name gt is the name of the CHOICE alternative If a CHOICE alternative is not given an explicit name then lt element name gt is automatically generated by taking the type name and making the first letter lowercase this is the same as was done for the ASN 1 SEQUENCE type with unnamed elements If the generated name is not unique a sequential number is appended to make it unique The union of choice alternatives is made of the equivalent C or C type definition followed by the element name for each of the elements The rules for element generation are essentially the same as was described for SEQUENCE above Constructed types or elements that map to C structured types are pulled out and temporary types are created Unnamed elements names are automatically generated from the type name by making the first character of the name lowercase One difference between temporary types used in a SEQUENCE and in a CHOICE is that a pointer variable will be generated for use within the CHOICE union construct ASN 1 production lt name gt CHOICE lt elementl name gt lt elementl type gt lt element2 name gt lt element2 type gt Generated C code define T_ lt name gt _ lt elementl name gt 1 define T_ lt name gt _
148. aps this function This function is invoked through the class interface to decode an ASN 1 message into the variable referenced in the msgData component of the class In this version there are three types of streams file socket and memory The most useful are file and socket streams It is possible to decode data directly from a file or socket without intermediate 177 Generated Streaming C Function Format and Calling Parameters copying into memory If the full amount of data is not available for reading then the behavior of these streams will be different the file and memory input streams will report an error the socket input stream will block until data is available or an I O error occurs for example the remote side closes the connection Generated Streaming C Function Format and Calling Parameters The format of the name of each streaming decode function generated is as follows asn1lBSD_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows status asnlBSD_ lt name gt OSCTXT pctxt lt
149. as above with the suffix _PDU This function does not contain the elemName and nsPrefix arguments these are built into the function as defined in the schema For this reason calling PDU functions is usually more conve nient than calling the equivalent function for the referenced type Procedure for Calling C Encode Functions This section describes the step by step procedure for calling C XML encode functions This pro cedure is similar to that for the other encoding methods except that some of the functions used are specific to XML Before an XML encode function can be called the user must first initialize an encoding context block structure The context block is initialized by calling rtXmlInitContext to initialize a context block structure The user then must call the rtXm SetEncBufPtr function to specify a message buffer to receive the encoded message Specification of a dynamic message buffer is possible by setting the buffer address argument to null and the buffer size argument to zero An encode function can then be called to encode the message If the return status indicates success then the message will have been encoded in the given buffer XML encoding starts from the begin ning of the buffer and proceeds from low memory to high memory until the message is complete This differs from BER where encoding was done from back to front Therefore the buffer start address is where the encoded XML message begins If a dynamic message buffer
150. associated with ASN E RANGERR This indicates the value is not within defined range for its associated type ASN E VALPARSE This indicates a general failure to parse a value definition It would be raised for example if a floating point number was used as part of a SIZE constraint ASN E INVRANGE ASN E IMPORTMOD This indicates an invalid range specification for example when the lower bound is greater than the upper bound This indicates that the specified import module object was not found ASN E NOTSUPP This indicates that the requested functionality is not sup ported by the compiler Most often the error is raised when generating test code for complex value definitions ASN E IDNOTFOU This indicates the compiler was unable to look up the spec ified identifier ASN E NOFIELD ASN E DUPLNAME This indicates that the specified field could not be found in the named class This indicates the specified name is already defined ASN W UNNAMED This warning is raised when specifications use unnamed fields These fields not allowed in X 680 but ASN1C sup ports them for purposes of backwards compatibility with X 208 268 General Status Messages Error Code Error Description ASN E UNDEFOBJ ASN E ABSCLSFLD This indicates that the named object is not defined within context of the requested module This indicates that the specified field is absent in
151. be isolated to a given production processing function Once the code is debugged this option should not be used as it adversely af fects performance 18 Running ASNIC from the Command line Option Argument Description usepdu vcproj lt PDU type name gt This option is used to specify the name of the Protocol Data Unit PDU type to be used in gen erated reader and writer programs This option instructs the compiler to gener ate Visual C or Visual Studio compatible project files to compile generated source code This is a Windows only option By passing one of the listed years the compiler will generate a project that links against libraries provided for those versions of Visual Studio For example specifying 2008 will generate a project that links against libraries in the _vs2008 directory Not specifying a year will cause the compiler to link against libraries compiled for Visual Studio 6 0 A custom build rule is generated that deletes the generated source files and then invokes ASNIC to regenerate them when a rebuild is done Doing a clean operation will cause the generated source files to be deleted a subsequent build will regen erate them For Visual C 6 0 project files you can see this build rule by locating the first ASN 1 file under the Source Files for the project right clicking it choosing Settings and then choosing the Cus tom Build tab For Visual Studio 2005
152. before some setup is required to perform the decode ApduType data OSCTXT CEXt OSBOOL trace TRUE verbose FALSE const char filename message dat int i stat Initialize context structure stat mderInitContext amp ctxt 214 Two phase Decoding if stat 0 rtxErrPrint amp ctxt return stat rtxSetDiag amp ctxt verbose In this case the content is read from an input file so a file stream is created using rtxStreamFile CreateReader Thereafter the PDU data type is initialized using its initialization function and the message is decoded with the generated mpERDec function Create file input stream stat rtxStreamFileCreateReader amp ctxt filename if 0 stat rtxErrPrint tect xt rtFreeContext amp ctxt return stat asnlInit_ApduType amp data Call compiler generated decode function stat MDERDec_ApduType amp ctxt amp data if stat 0 printf decode of ApduType failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt return 1 rtxStreamClose amp ctxt The second phase of the decode can now proceed Because the open type data can appear in a list a while loop is used to cycle through the data Decode APDU open type data if data t T_ApduType_aarq OSRTDListNode pnode data u aarg gt data_proto_list head while 0 pnode PhdAssociationInformation phdAssocInfo
153. bject amp object 0 virtual int decodeBERType OSCTXT pctxt ASN1ITObject amp object 0 OSBOOL isParameterTypePresent if m ParameterTypePresent return TRUE else return FALSE virtual int encodeBERParameterType OSCTXT pctxt ASN1TObject amp object return 0 virtual int decodeBERParameterType OSCTXT pctxt ASN1TObject amp object return 0 inline OSBOOL idEquals ASN1TObjId pvalue return 0 rtCmpTCOID amp id pvalue 7 This assumes that only BER or DER was specified as the encoding rules type First notice that member variables have been generated for the fixed type fields in the definition These include the ia field Information object classes derived from this definition are expected to populate these fields in their constructors Also virtual methods have been generated for each of the type fields in the class These include the Type fields The method generated for Type is abstract and must be implemented in a derived information object class The method generated for the Parametertype field has a default imple mentations that does nothing That is because it is a optional field Also generated are Equals methods for the fixed type fields These are used by the generated code to verify that data in a generated structure to be encoded or data that has just been decoded matches the table constraint values Th
154. ble a normal status is returned Simple Table Constraint 1 This function will verify all the fixed type values match what is defined in the table constraint object set If an element value does not exist in the table i e the information object set and the object set is not extensible then a table constraint violation exception will be thrown General Procedure for Table Constraint Encod ing The general procedure to encode an ASN 1 message with table constraints is the same as without table constraints The only difference is in the open type data population procedure The table unions option will cause union structure to be generated for open type field containing relationsal table constraints These are populated for encoding in much the same way CHOICE onstructs are handled The tables option will cause ASN TObject fields to be inserted in the generated code instead of AsnI OpenType declarations The procedure to populate the value for an ASN TObDject item is as follows 1 Check the ASN 1 specification or generated C code for the type of the type field value in the information object set that corresponds to the selected key field value 2 Create a variable of that type and assign a pointer to it to the Asn Object decoded member variable as void 3 Follow the common BER PER DER encode procedure A complete example showing how to assign an open type value in the legacy tables case is as follows Test DEFINITIONS
155. ble of type OSCTXT This variable holds all of the working data used during the decod ing of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished by using the rtInitContext function Also the context must be initialized for streaming operations by calling the rtxStreamInit function OSCTXT ctxt context variable if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 rtxStreamInit amp ctxt Initialize stream The next step is to create a stream object within the context This object is an abstraction of the output device to which the data is to be encoded and is initialized by calling one of the following functions e rtxStreamFileOpen e rtxStreamFileAttach e rtxStreamSocketAttach e rtxStreamMemoryCreate 224 Procedure for Calling C Decode Functions e rtxStreamMemoryAttach The flags parameter of these functions should be set to the OSRTSTRMF_INPUT constant value to indicate an input stream is being created see the C C Common Run Time Library Reference Manual for a full description of these functions A decode function can then be called to decode the message If the return status indicates success 0 then the message will have been decoded into the given ASN 1 typ
156. cause the identifiers are wrapped in a struct declaration which provides a namespace for the values see the C section below for more details In addition to the generated type definition helper functions are also generated to make it easier to convert to from enumerated and string format The signatures of these functions are as follows const OSUTF8CHAR lt name gt _ToString OSINT32 value int lt name gt _ToEnum OSCTXT pctxt const OSUTF8CHAR value lt name gt pvalue The first function would be used to convert an enumerated value into string form The second would do the opposite convert from string to enumerated C Mapping ASN 1 production lt name gt ENUMERATED lt idl gt lt vall gt lt id2 gt lt val2 gt 52 NULL Generated code struct lt name gt enum Root idl vall id2 val2 enum Ext extidl extvall bi typedef OSUINT32 ASN1T_ lt name gt The struct type provides a namespace for the enumerated elements This allows the same enumer ated constant names to be used in different productions within the ASN 1 specification An enu merated item is specified in the code using the lt name gt lt id gt form Every generated definition contains a Root enumerated specification and optionally an Ext spec ification The Root specification contains the root elements of the type or all of the elements if it is not an extended type
157. codeBuffer msgbuf len ASN1T_Invoke msgData ASN1C_Invoke invoke decodeBuffer msgData step 3 call decode function if status invoke Decod 0 decoding successful data in msgData use key field value to set type of message data ASNIOBJID oidl 3 0 1 1 ASNIOBJID oid2 3 0 1 2 if msgData opcode oidl argument is a VisibleString ASN1VisibleString pArg ASN1IVisibleString msgData argument decoded else if msgData opcode oid2 argument is an INTEGER OSINT32 arg OSINT32 msgData argument decoded else error processing 138 General Procedure for Ta ble Constraint Decoding present in msgData argument encoded field and it would be up to the user to determine how to process it The decoding procedure for C requires one additional step This is a call to the module initialization functions after context initialization is complete All module initialization functions for all modules in the project must be invoked The module initialization function definitions can be found in the lt ModuleName gt Table h file A C program fragment that could be used to decode the Invoke example is as follows include TestTable h include fil main OSOCTET msgbuf 1024 ASN1ITAG msgtag int msglen OSCTXT ctxt Invoke invoke ASN1LOBJID oidl1l 3 0 1 1 ASNLOBJID
158. coding a Series of Messages Using the C Encode Functions ceeeeeeeeeeeeees 209 Generated IMDER Decode Functions i c sc2csseeesstevetiee ined anid nteneeuseeialdanueiae 209 Generated C Function Format and Calling Parameters cceescceceseceeeseeeeeteeees 209 Procedure for Calling C Decode Functions 000 0 eee eeeceeceeeseeeneeeeseceeeeeeeeeeaeeeaeenes 210 Decoding a Series of Messages Using the C Decode Functions eeeeeeeee 211 Two Phase Messaging ui hcaceussiacienyidesash cucasvassdsadasutinn ss E E O GAE RE AAE E 212 Two phase Encoding facssasorsecsstccedsaneacaaselsbeneetivnvalatedynat aasaenevateseauaad vodanegsdeeneonneaeaaees 212 Two phase Decoding siicczi sass iaccics tna nigeaacasusians ils anes E A a dae ae 214 Generated XML PunctiOns 2 ciiges tele BAN ree ack iat Ale RNa setae aes Eee eres 217 Generated XER Encode Functions i c st eiiescantiniis ae aiehdadiieean ecu a laiees 217 Generated C Function Format and Calling Parameters cceeecceeeseceeeteeeenteeees 217 Generated C Encode Method Format and Calling Parameters 0 0 eeeeeeeeees 218 Procedure for Calling C Encode Functions oo cee ceeeesceesseceseceeeeesseecnaeenseenseeeeaees 218 Procedure for Using the C Control Class Encode Method 220 Generated XER Decode Functions 5356 2 jc sears coli Oh peanta eet eae ath Daa etaanrdeu 221 Procedure for Using the C Interface gt sci scctadcitsssiecssstiaeesceeddans sieeddstathecens sean ugeaeten 223
159. coding is to be done specified by the use of the stream ASN1C command line option In this case the procedures described in the Generated BER Streaming Encode Functions section Before any encode function can be called the user must first initialize an encoding context This is a variable of type OSCTXT This variable holds all of the working data used during the encod ing of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished by using the rtInitContext function as follows OSCTXT ctxt if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 The next step is to specify an encode buffer into which the message will be encoded This is accom plished by calling the xe_setp run time function The user can either pass the address of a buffer and size allocated in his or her program referred to as a static buffer or set these parameters to zero and let the encode function manage the buffer memory allocation referred to as a dynamic buffer Better performance can normally be attained by using a static buffer because this eliminates the high overhead operation of allocating and reallocating memory After initializing the context and populating a variable of the structure to be encoded an encode fu
160. config gt lt storage gt dynamic lt storage gt lt asnlconfig gt This specification indicates dynamic storage should be used in all places where its use would result in significant memory usage savings within all modules in the specified source file lt asnlconfig gt lt module gt lt name gt H323 MESSAGES lt name gt lt sourceFile gt h225 asn lt sourceFile gt lt typePrefix gt H225 lt typePrefix gt lt module gt lt asnlconfig gt This specification applies to module H323 MESSAGES in the source file being processed For IMPORT statements involving this module it indicates that the source file h225 asn should be searched for specifications It also indicates that when C or C types are generated they should be prefixed with H225 This can help prevent name clashes if one or more modules are involved and they contain productions with common names The following tables specify the list of attributes that can be applied at all of the different levels global module and individual production Global Level 34 Compiler Configuration File These attributes can be applied at the global level by including them within the lt asniconfig gt sec tion Name Values Description lt events gt lt events gt lt rootdir gt lt rootdir gt defaultValue keyword lt ASNIC root directo ry gt This configuration item is for use with Event Handling as described in a
161. crosoft XML parser MSXML The GNOME libxml2 parser and the XERCES XML parser Interfacing to other parsers only requires building an abstraction layer to map the common interface to the vendor s interface A diagram showing the components used in the XML decode process is as follows Step 1 Generate code C header file struct MySeq int a bool b char c MySeq SEQUENCE a INTEGER b BOOLEAN C source file startElement c UTF8String characters endElement Step 2 Build Application XML document Populated data var oxi XML Parser ASNIC generated SAX handlers ASNIC generates code to implement the following methods defined in the SAX content handler interface startElement characters 222 Procedure for Using the C Interface endElement The interface defines other methods that can be implemented as well but these are sufficient to decode XER encoded data Procedure for Using the C Interface The ASNIC compiler generates XER decode functions for C for constructed types in a specifica tion These can be invoked in the same manner as other decode functions In this case they install the generated SAX content handler functions and invoke the XML parser s parse function to parse a document The procedure to call these generated functions is described below Generated C Function Format and Calling Pa rameters The format of t
162. ction result variable stat returns the status value from the PER encode function This status value will be 0 0 if encoding was successful or a negative error status value if encoding fails Return status values are defined in the asnItype h include file The user must call the encode buffer class methods getMsgPtr and getMsgLen to obtain the starting address and length of the encoded message component Populating Generated Structure Variables for Encoding See the section Populating Generated Structure Variables for Encoding for a discussion on how to populate variables for encoding There is no difference in how it is done for BER versus how it is done for PER Procedure for Calling C Encode Functions This section describes the step by step procedure for calling a C PER encode function This method must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done Before a PER encode function can be called the user must first initialize an encoding context block structure The context block is initialized by calling the rt nitContext to initialize the block The user then must call pu_setBuffer to specify a message buffer to receive the encoded message Specification of a dynamic message buffer is possible by setting the buffer address argument to null and the buffer size argument to zero The pu_setBuffer function also allows for the specificatio
163. ction is generated to make it easier to find an item in the list based on the key field The general format for this type of function is as follows lt ProtocolIE FieldType gt asnlGet_ lt ProtocollEsType gt lt KeyFieldType gt lt key gt lt ProtocollEsType gt plist In this definition lt ProtocolIEsType gt refers to the main list type SEQUENCE OF definiing the information element list lt ProtocolIE FieldType gt is the type of an element within this list and lt KeyFieldType gt is the type of index key field An example of this type of function from the 1AP definitions is as follows Get IE using id key value HandoverRequired_protocollEs_element asnlGet_HandoverRequired_protocollEs ProtocolIE_ID id HandoverRequired_protocollIEs plist Generated C Classes and Methods This section discusses items that are generated idfferently for C for union table constraints Choice Selector TVALUE Type For C an enumerated type is generated for each of the options in a type field union These corre spond to each of the items in the information object set associated with the union For example the TVALUE type generated for SIAP_ELEMENTARY_PROCEDURES is as follows typedef enum T_S1AP_PDU_Descriptions_S1AP_ELEMENTARY_PROCEDURES_UNDEF_ T_S1IAP_PDU_Descriptions_S1AP_ELEMENTARY_PROCEDURES_handoverPreparation T_S1IAP_PDU_Descriptio
164. ctory the name does not matter and lib src rt src and build_lib subdirectories note in these definitions is a wildcard character indicating there are multiple directories matching this pattern The tree should be as follows pe build lib 2 Copy the files ending in extension mk from the root directory of the installation to the root directory of the target platform note if transferring from DOS to UNIX or vice versa FTP the files in ASCII mode to ensure lines are terminated properly 3 Copy all files from the src and the different rt src subdirectories from the installation to the src and rt sre directories on the target platform note if transferring from DOS to UNIX or vice versa FTP the files in ASCII mode to ensure lines are terminated properly 4 Copy the makefile from the build_lib subdirectory of the installation to the build_lib subdirec tory on the target platform note if transferring from DOS to UNIX or vice versa FTP the files in ASCH mode to ensure lines are terminated properly 5 Edit the platform mk file in the root subdirectory and modify the compilation parameters to fit those of the compiler of the target system In general the following parameters will need to be adjusted a cc C compiler executable name b ccc C compiler executable name 32 Compiler Configuration File c crLacs_ Flags that should be specified on the C or C command line The platform w32 and platform
165. d It is possible to perform XML to binary transcoding of a multi part message for example a SOAP message by decoding each part and then reencoding in binary form and switching the content type within this structure An example of a sequence with a single wildcard element is as follows lt xsd complexType name MyType gt lt xsd sequence gt lt xsd element name ElementOne type xsd string gt lt xsd element name ElementTwo type xsd int gt lt xsd any processContents lax gt lt xsd sequence gt lt xsd complexType gt The generated C type definition is as follows typedef struct EXTERN MyType const OSUTF8CHAR elementOne OSINT32 elementTwo OSXSDAny elem MyType As per the X 694 standard the element was given the standard element name elem 103 XML Attribute Declarations XML Attribute Declarations XML attribute declarations in XSD are translated into ASN 1 elements that are added to a SE QUENCE type In binary encodings there is no way to tell encoded attributes apart from encoded elements They just represent data fields in ASN 1 For XML special logic is added to the gener ated XML encoders and decoders to encode and decode the items as attributes An example of an attribute being added to an xsd sequence declaration is as follows lt xsd complexType name Name gt lt xsd sequence gt lt xsd element name givenName type xsd string gt lt xsd element name i
166. d close the stream if stat 0 error processing rtxStreamClose amp ctxt In general streaming encoding is slower than memory buffer based encoding However in the case of streaming encoding it is not necessary to implement code to write or send the encoded data to an output device The streaming functions also use less memory because there is no need for a large destination memory buffer For this reason the final performance of the streaming functions may be the same or better than buffer oriented functions Encoding a Series of Messages Using the Streaming C Encode Functions A common application of BER encoding is the repetitive encoding of a series of the same type of message over and over again For example a TAP3 batch application might read billing data out of a database table and encode each of the records for a batch transmission Encoding a series of messages using the streaming C encode functions is very similar to encoding of one message All that is necessary is to set up a loop in which the asn BSE_ lt name gt functions will be called It is also possible to call different asn BSE_ lt name gt functions one after another An example showing how to do this is as follows 160 Generated Streaming C Encode Method Format and Calling Parameters include employee h include file generated by ASNI1C int main int stat OSCTXT CExt Employee employee typedef gen
167. d in the Information Object Set initialization function TypeSize sizeof _name_Type SupportedAttributes encodeType asnlE__name_Type SupportedAttributes decodeType asn1D__name_Type SupportedAttributes 0 0 0 SupportedAttributes 0 id numids 3 0 0 0 SupportedAttributes id subid 0 OF SupportedAttributes id subid 1 1 SupportedAttributes id subid 2 1 95 Legacy Table Constraint Model SupportedAttributes 1 TypeSize sizeof _commonName_Type SupportedAttributes 1 encodeType amp asnlE__commonName_Type SupportedAttributes 1 decodeType amp asn1D__commonName_Type SupportedAttributes 1 id numids 3 SupportedAttributes 1 id subid 0 0 SupportedAttributes 1 id subid 1 1 SupportedAttributes 1 id subid 2 1 SupportedAttributes 1 id subid 3 1 C Code Generation In C ASN 1 information object sets are mapped to C classes In this case a C singleton class is generated This class contains a container to hold an instance of each of the ASN 1 infor mation object C objects in a static array The class also contains an object lookup method for each of the key fields Key fields are identified in the class as either a fields that are marked unique or b fields that are referenced in table constraints with the notation The generated constructor initializes all required values and information objects An ex
168. d messag Generated XER Decode Functions NOTE XER is maintained as a legacy XML format for ASN 1 New applications should consider using XML as described in the next section instead of XER XML is more closely aligned with W3C standard XML and XML schema The code generated to decode XML messages is different than that of the other encoding rules This is because off theshelf XML parser software is used to parse the XML documents to be decoded This software contains a common interface known as the Simple API for XML or SAX that is a de facto standard that is supported by most parsers ASN1C generates an implementation of the content handler interface defined by this standard This implementation receives the parsed XML data and uses it to populate the structures generated by the compiler The default XML parser used is the EXPAT parser http expat sourceforge net This is a lightweight open source parser that was implemented in C The C SAX interface was added by 221 Generated XER Decode Functions adapting the headers of the Apache XERCES C XML Parser http xml apache org to work with the underlying C code These headers were used to build a common C SAX interface across different vendor s SAX interfaces unlike Java these interfaces are not all the same The ASN1C XER SAX C and C libraries come with the EXPAT parser as the default parser and also include plug in interfaces that allow the code to work with the Mi
169. d or decoded The message buffer object is a work buffer object for encoding or decoding The interface reference can also be used to specify a stream Stream classes are derived from this same base class The data type reference is a reference to the ASN T_ variable that was generated for the data type EncodeFrom and DecodeTo methods are declared that wrap the respective compiler generat ed C encode and decode stream functions Standard Encode and Decode methods exist in the ASN1CType base class for direct encoding and decoding to a memory buffer Command line op tions may cause additional methods to be generated For example if the print command line ar gument was specified a Print method is generated to wrap the corresponding C print function Specification of the XML encoding rules option xer causes a number of additional methods to be generated for constructed types These additional methods are implementations of the standard Simple API for XML SAX content handling interface used to parse content from XML messages The startElement characters and endElement methods are implemented as well as additional sup port methods The control class is also defined to inherit from the ASN XERSAX Handler base class as well as ASN CType or one of its descendents The equivalent C and C type definitions for each of the various ASN 1 types follow Generated C Source Files By default the ASN1C compiler generates the following set of c
170. d to all generated C and C typedef names note for C the prefix is applied after the standard ASN1T_ prefix This can be used to prevent name clashes if multiple modules are involved in a compilation and they all contain common names This is used to specify a prefix that will be applied to all generated enumerated identifiers within a module This can be used to prevent name clashes if multiple modules are involved in a compilation note this attribute is normally not needed for C enumerated identifiers be cause they are already wrapped in a structure to allows the type name to be used as an additional identifier 37 Compiler Configuration File Name Values Description lt valuePrefix gt lt val prefix text uePrefix gt lt classPrefix gt classPrefix gt lt prefix text This is used to specify a prefix that will be ap plied to all generated value constants within a module This can be used to prevent name clash es if multiple modules are involved that use a common name for two or more different value declarations This is used to specify a prefix that will be ap plied to all generated items in a module derived from an ASN 1 CLASS definition lt objectPrefix gt lt ob prefix text jectPrefix gt This is used to specify a prefix that will be ap plied to all generated items in a module derived from an ASN 1 Information Object definition lt object
171. d type definitions will cause the compiler to search and generate code for modules specified in the imports statement of an ASN 1 specification Basic encoding rules are selected by default Only one of BER DER and CER can be checked at any time XML and XER are also mutually exclusive options Generated function options are shown in the following tab 24 Common Code Generation Options Common Code Generation Options Language Options Function Options Utility Options Generated Function Types V Encode Copy Print Functions V Decode Compare E Stream Print Format Constraints Do not generate constraint checks Jax Enable strict constraint checks strict Generate code to handle table constraints tables legacy setting in C C Do not generate inline containing types noContaining Space Optimization Generate compact code compact Do not generate indefinite length processing code noIndefLen Do not generate code to save restore unknown extensions noOpenExt Do not generate types for items embedded in information objects E Do not generate XML namespaces for ASN 1 modules noxmins F Generate short form of type names shortnames The options in this tab control which functions are generated and what modifications are made to those functions By default encoding and decoding functions are generated by the compiler If the target applica tion does not require enc
172. declared that will be replaced with actual parameters when the type is referenced This is similar to templates in C A simple and common example of the use of parameterized types is for the declaration of an upper bound on a sized type as follows SizedOctetString INTEGER ub OCTET STRING SIZE 1 ub In this definition ub would be replaced with an actual value when the type is referenced For example a sized octet string with an upper bound of 32 would be declared as follows OctetString32 SizedOctetString 32 The compiler would handle this in the same way as if the original type was declared to be an octet string of size 1 to 32 That is it will generate a C structure containing a static byte array of size 32 as follows typedef struct OctetString32 73 Parameterized Types OSUINT32 numocts OSOCTET data 32 OctetString32 Another common example of parameterization is the substitution of a given type inside a common container type For example security specifications frequently contain a signed parameterized type that allows a digital signature to be applied to other types An example of this is as follows SIGNED ToBeSigned SEQUENCE toBeSigned ToBeSigned algorithmOID OBJECT IDENTIFIER params Params signature BIT STRING An example of a reference to this definition would be as follows SignedName SIGNED Name
173. dvashavensaavecsceubnscnedenwesaatesupenens 121 Generated Encode Decode Function and Methods s nssssssssssssssessseeessseesseessessseresseessseesseesse 123 Encode Decode Function Prototypes wisi ciicciaitiseecsaaveseaesscncsansaeaasadeseadensnaceedasscvancncvesacees 123 Generated C Control Class Definition 200 0 ccc cecccccesccecsseceesscceessccecnsccesssecesseceeseeeoes 124 BER DER or PER Class Definition i isis gsacciasaceesssdsvedaseceaces sabeatesavaradeasdveedsensncceaesenys 124 XER Class Definition senansa en a a R E E seats E R 126 Generated Methods cx ccsssieverscdisasecdsaseopcdaatadenedaanaveasisepeaceasuaccaus E EEN E REEE 127 Generated Information Object Table Structures sesssseesseessesssessseessseesseessesseesseeesseee 127 Simple Form Code Generation sisiscccinacascaselesiadsasanecteasdsvestaveacdssoteeeendvacaatesdendesusencen 129 Unions Table Form Code Generation ssssesssssesesesessstesseesserssereseessseesseesseesseesseee 129 Legacy Table Form Code Generation ccceescccsssecesscecseececeeneeceeeecsueeecseeeeenaeees 131 Additional Code Generated with the tables option s ssssssssssesssessssseessressesseesseee 131 General Procedure for Table Constraint Encoding 000 eee eeeeceeeeseeeenteeeesteeeeneeeees 134 iv ASNIC General Procedure for Table Constraint Decoding eee eeeeeeeseceeeteeeenneeeeneeeenes 137 General Procedures for Encoding and Decoding 00 cee
174. e EncodeTo out can be used here if if or employ step 5 out getsS printf out print tatus 0 Encoding failed ErrorInfo return 1 trace printf EncodeTo method heck status of the operation Status i n out getStatus Encoding was successful n Encoding a Series of Messages Using the Streaming C Control Class Interface Encoding a series of messages using the streaming C control class is similar to the C method of encoding All that is necessary is to create a loop in which EncodeTo or Encode methods will be called or the overloaded lt lt streaming operator It is also possible to call different EncodeTo methods or Encode or operator lt lt one after another An example showing how to do this is as follows include employee h f include rtbersrc ASNIBEREncodeStream h include file generated by ASNI1C include rtxsrc OSRTFileOutputStream h 163 Generated BER Decode Functions int main const int msglen char filenam OSOCTET msgptr OSOCTET msgbuf 1024 const step 1 ASNIBEREncodeStream out 0 if out getStatus out printErroriInfo return 1 step 2 message dat construct stream object new OSRTFileOutputStream filename construct ASN1C C generated class ASN1T_Pe
175. e The Project Wizard will allow you to save your compilation options and file settings into a project file and retrieve them later If you wish to make a new project click the icon next to Create a New Project Get Project File Name WW 4 Saree WI rm cpp gt sample ber gt employee Search employee Organize v New folder cd EE Desktop Name Date modified Type B Downloads TEF g A employee acp 3 16 2010 11 19AM ACP File T Recent Places 33 Libraries Documents d Music Pictures f Videos jE Computer fly COMPAQ C a FACTORY_IMAGI v Filename Gua cScss Save as type acproj acp Hide Folders 21 Using Projects Previously saved projects may be recalled by clicking the icon next to Open an Existing Project r Load ASNIC Project OO d cpp gt sample_ber gt employee Searc Organize v New folder s m Fr Favorites Name Date modified Type E Desktop _ employee acp 3 16 2010 11 19AM ACP File B Downloads Recent Places 3 Libraries Documents d Music Pictures amp Videos m jE Computer fly COMPAQ C ca FACTORY_IMAGI lt K D s File name employee acp v acproj acp on fe ne The project format has changed in ASNIC 6 3 to help accommodate the transition to Qt 4 5 Changes to the interface necessitated changes to the underlying project file format Pro
176. e These functions have the following proto types BER DER int asnlETC_ lt ProdName gt OSCTXT pctxt 132 Additional Code Generat ed with the tables option lt ProdName gt pvalue lt ClassName gt pobject int asnlDTC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue lt ClassName gt pobject PER int asnlPETC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue lt ClassName gt pobject int asnlPDTC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue lt ClassName gt pobject These prototypes are identical to the prototypes generated in C code generation case except for the addition of the pobject argument This argument is for a pointer to the information object that matches the key field value for a given encoding These functions have different logic for process ing Relative and Simple table constraints The logic associated with each case is as follows On the encode side Relative Table Constraint 1 The lookupObject method is invoked on the object set instance to find the class object for the data in the populated type variable to be encoded 2 If amatch is found the table constraint encode function as defined above is invoked This func tion will verify all fixed type values match what is defined in the information object definition and will encode all type fields and store the resulting encoded data in the ASN TObject encoded fields 3 Ifa match is
177. e notypes option along with the events option In this case no backing data types to hold decoded data are generated Instead parsing functions are generated that store the data internally within local variables inside the parsing functions This data is dispatched to the callback functions and immeditely disposed of upon return from the function It is up to the user to decide inside the callback handler what they want to keep and they must make copies at that time The result is a very fast and low memory consuming parser that is ideal for parsing messages in which only select parts of the messages are of interest Another use case for pure parser functions is validation These functions can be used to determine if a PER message is valid without going through the high overhead operation of decoding They can be used on the front end of an application to reject invalid messages before processing of the messages is done In some cases this can result in significantly increased performance 256 How to Use It An example of a pure parser can be found in the cpp sample_per per2xmlEH directory This pro gram uses a pure parser to convert PER encoded data into XML The steps in creating an event handler are the same as in Example 1 above An implementation of the Asn NamedEventHandler interface must be created This is done in the xmlHandler h and xmlHandler cpp files A detailed discussion of this code will not be provided here What it does i
178. e are inconsistent ASN E NOPDU This indicates that a PDU type was not found for generat ing a reader or writer program General Status Messages The following table contains both system and validation failures that may occur during program execution These failures do not arise from ASN 1 specific features such as an invalid PER en coding but instead comprehend such failures as buffer overflows invalid socket options or closed streams 269 General Status Messages Error Code Error Name Description 0 2 RT_OK RT_OK_FRAG Normal completion status Message fragment return status This is returned when a part of a message is successfully de coded The application should continue to in voke the decode function until a zero status is returned RTERR_BUFOVFLW Encode buffer overflow This status code is re turned when encoding into a static buffer and there is no space left for the item currently being encoded RTERR_ENDOFBUF Unexpected end of buffer This status code is returned when decoding and the decoder expects more data to be available but instead runs into the end of the decode buffer RTERR_IDNOTFOU RTERR_INVENUM Expected identifier not found This status is re turned when the decoder is expecting a certain element to be present at the current position and instead something different is encountered An example is decoding a sequence container type in w
179. e functions are nested to accomplish decoding of complex variables At the top level these parameters should always be set to the constants ASNIEXPL and zero respectively The function result variable status returns the status of the decode operation The return status will be zero if decoding is successful or negative if an error occurs Return status values are defined in the asnltype h include file Procedure for Calling C Decode Functions This section describes the step by step procedure for calling a C BER or DER decode function This method must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done 165 Generated C Function For mat and Calling Parameters Before any decode function can be called the user must first initialize a context variable This is a variable of type OSCTXT This variable holds all of the working data used during the decoding of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished as follows OSCTXT ctxt if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return l The next step is the specification of a buffer containing a message to be decoded This is accom plis
180. e tag for type of message received note this is optional the decode function can be called directly if the type of message is known if stat berDecStrmPeekTagAndLen amp ctxt amp tag amp len 0 rtxErrPrint amp ctxt return stat if msgtag TV_PersonnelRecord Step 4 Call decode function note last two args should always be ASN1EXPL and 0 status asnlBSD_PersonnelRecord amp ctxt amp employee ASN1EXPL 0 Step 5 Check return status if status 0 process received data in employee variable else error processing else check for other known message types Step 6 Close the stream rtxStreamClose amp ctxt 180 Generated Streaming C Function Format and Calling Parameters Remember to release dynamic memory when done rtFreeContext amp ctxt Decoding a Series of Messages Using the Streaming C Decode Functions The above example is fine as a sample for decoding a single message but what happens in the more typical scenario of having a long running loop that continuously decodes messages It will be necessary to put the decoding logic into a loop A code fragment showing a way to do this is as follows include employee h include file generated by ASNIC include rtxsrc rtxStreamFile h main ASNITAG msgtag int msglen stat OSCTXT ctxt PersonnelRecord empl
181. e tags enum and ext lt items gt is an optional parameter If it is not specified it is assumed that application informa tion should be produced for all three item class es ASN 1 tags ASN 1 enumerations and ex tended elements ber None This option instructs the compiler to generate functions that implement the Basic Encoding Rules BER as specified in the X 690 ASN 1 standard bindir lt directory gt This option is used in conjunction with the gen Make option to specify the name of the binary executable directory to be added to the make file Linked executable programs will be output to this directory bitMacros None This option instructs the compiler to generate ad ditional macros to set clear and test named bits in BIT STRING constructs By default only bit number constants are generated Bit macros pro vide slightly better performance because mask values required to do the operations are comput ed at compile time rather than runtime C None Generate C source code c or csharp None Generate C source code See the ASNIC C User s Guide for more information and options for generating C code c or cpp None Generate C source code Cer None This option instructs the compiler to gener ate functions that implement the Canonical En coding Rules CER as specified in the X 690 ASN 1 standard cfile lt filename gt This
182. e variable The decode function may automatically allocate dynamic memory to hold variable length items during the course of decoding This memory will be tracked in the context structure so the programmer does not need to worry about freeing it It will be released when the context is freed The final step of the procedure is to close the stream and free the context block The function to free the context is rtFreeContext A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main int stat OSCTXT ctxt PersonnelRecord employee ASN1ConstCharPtr filename message xml Step 1 Init context structure if rtInitContext amp ctxt 0 return 1 rtxStreamInit amp ctxt Step 2 Open a stream stat rtxStreamFileOpen amp ctxt filename OSRTSTRMF_INPUT if stat 0 rtErrPrint amp ctxt errInfo return 1 Step 3 decode the record stat asnlXD_PersonnelRecord amp ctxt amp employee if stat 0 if trace printf Decode of PersonnelRecord was successful n printf Decoded record n asnilPrint_PersonnelRecord Employee amp employee else printf decode of PersonnelRecord failed n rtxErrPrint amp ctxt rtxStreamClose amp ctxt return 1 225 Procedure for Using the C Interface Step 4 Close the stream a
183. eBuffer class has a standard method for parsing the initial tag length from a message to determine the type of message received This call is used in conjunction with a switch statement on generated tag constants for the known message set in order to pick a decoder to call Once it is known which type of message has been received an instance of a generated message class can be instantiated and the decode function called The start of message pointer and message length if known must be specified either in the constructor call or in the call to the decode function itself A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNI1C main OSOCTET msgbuf 1024 ASN1TAG msgtag int msglen status logic to read message into msgbuf Use the ASNIBERDecodeBuffer class to parse the initial tag length from the message ASNIBERDecodeBuffer decodeBuffer msgbuf len status decodeBuffer ParseTagLen msgtag msglen if status 0 handle error Now switch on initial tag value to determine what type of message was received switch msgtag 170 Generated C Decode Method Format and Calling Parameters case TV_PersonnelRecord compiler generated constant ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ decodeBuffer msgData if status employee
184. ecoded data must then be initialized This can be done by either initializing the variable to zero using memset or by calling the ASNIC generated initialization function A decode function can then be called to decode the message If the return status indicates success 0 then the message will have been decoded into the given ASN 1 type variable The decode function may automatically allocate dynamic memory to hold variable length variables during the course of decoding This memory will be tracked in the context structure so the programmer does not need to worry about freeing it It will be released when the context is freed The final step of the procedure is to free the context block This must be done regardless of whether the block is static declared on the stack and initialized using rtInitContext or dynamic created using rtNewContext The function to free the context is rtFreeContext A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main OSOCTET msgbuf 1024 ASNITAG msgtag int msglen stat OSCTXT ctxt OSBOOL aligned TRUE PersonnelRecord employee logic to read message into msgbuf This example uses a static context block step 1 prepare the context block stat rtInitContext amp ctxt if stat 0 196 Procedure for Using the C Control Class Decode Method
185. ect TYP MME UE S1AP ID PRESENCE mandator HandoverType PRESENCE mandator In this case the name is formed by combining the information object set name with the name of each key field within the set Generated IE Append Function 85 Unions Table Constraint Model A user would need to allocate objects of this structure populate them and add them to the protocol IE list In order to make this easier helper functions are generated assist in adding information items to the list The general format of these append functions is as follows int asnlAppend_ lt ProtocollEsType gt _ lt KeyValueName gt OSCTXT pctxt lt ProtocollEsType gt plist lt ValueType gt value In this definition lt ProtocollEsType gt refers to the main list type SEQUENCE OF defining the information element list lt xeyvalueName gt is the name of the primary key field defined in the as sociated information object set lt valueType gt is the type of the value for the indexed information object set item An example of this type of function from the S1AP definitions is as follows Append IE with value type MME_UE_S1AP_ID to list int asnlAppend_HandoverRequired_protocollEs_id_MME_UE_S1AP_ID OSCTXT pctxt HandoverRequired_protocollIEs plist MME_UE_S1AP_ID value Generated IE Get Function In addition to the list append function a second type of helper fun
186. ed to be a C reserved word The base element is then added and is of type ostn7T32 the default type used for xsd integer In the case of a simple content restriction the processing is similar A complete new separate type is generated even if the result of the restriction leaves the original type unaltered i e the restriction is handled by code within the generated encode and or decode function This proves to be a cleaner solution in most cases than trying to reuse the type being restricted For example lt xsd complexType name SmallSizeType gt lt xsd simpleContent gt lt xsd restriction base SizeType gt lt xsd minInclusive value 2 gt lt xsd maxInclusive value 6 gt lt xsd attribute name system type xsd token use required gt lt xsd restriction gt lt xsd simpleContent gt lt xsd complexType gt This applies a restriction to the SizeType that was previously derived In this case the generated C type is as follows typedef struct EXTERN SmallSizeType const OSUTF8CHAR system_ OSINT32 base SmallSizeType In this case the type definition is almost identical to the original sizetType The only exception is that the bit mask field for optional elements is removed a consequence of the use required 106 xsd complexContent attribute that was added to the system attribute declaration The handling of the mintnclusive and maxInclusive attributes is handled inside the gene
187. ee the rtucsTocstring rtUCSToNewCString and the rtcToucsstring run time function descrip tions for information on utilities that can convert standard C strings to and from Universal Charac ter Set UCS 4 string format See also the rtucsTowcsstring and rtwcsToucsstring for informa tion on utilities that can convert standard wide character string to and from Universalstring type The utrsstring type is represented as a string of unsigned characters using the osutrscHar data type This type is defined to be unsigned char This makes it possible to use the characters in the upper range of the UTF 8 space as positive numbers The contents of this string type are assumed to contain the UTF 8 encoding of a character string For the most part standard C character string functions such as strcpy strcat etc can be used with these strings with some type casting Utility functions are provided for working with UTF 8 string data The UTF 8 encoding for a standard ASCII string is simply the string itself For Unicode strings represented in C C using the wide character type wchar_t the run time functions rtxuTFsTowcs and rtxwcsTouTFs can be used for converting to and from UTF 8 format The function rt xvalidateuTFrs can be used to ensure that a given UTF 8 encoding is valid See the C C Run Time Library Reference Manual for a complete description of these functions Time String Types The ASN 1 GeneralizedTime and UTCTime types are mapped to standard
188. eeeesceceeneeceeeeeceeeeeeeteeeeseeeeaaees 140 Dynamic Memory Management 2 222 c0 01iseis veneered 140 Populating Generated Structure Variables for Encoding cee eeeeeeseesseeeeeeeees 145 Accessing Encoded Message Components ceescecesscecseneeceeeeeceeeeecseeeeesteeeesaes 146 Generated BER FUnctions o2 i2 2222 issies tid Giset ele isi ek einai elaine 149 Generated BER Encode Functions ie1202 cheek ne ek Vile 149 Generated C Function Format and Calling Parameters ceeeceeeseceeseeeeenteeees 149 Generated C Encode Method Format and Calling Parameters eeeeeeeeees 154 Generated BER Streaming Encode Functions ecceesceeeeeceeeseeeceseeeceeeeecseeeesteeeenaeeees 157 Generated Streaming C Function Format and Calling Parameters eee 158 Generated Streaming C Encode Method Format and Calling Parameters 161 Generated BER Decode Functions tics2i cktn ci etddnavnniinlavidanianciets 164 Generated C Function Format and Calling Parameters ceeecceeseeeeeeteeeenteeees 165 Generated C Decode Method Format and Calling Parameters eee 169 BER Decode Performance Enhancement Techniques cccsescceceseeeeeseceeeneeeesteeeenaees 173 Dynamic Memory Management 4 22 2c4auneaiae ance deed aes 173 Compact Code Generation asiek vests nti pieces teetaai lie tewssestededh Hats eaten ieee 174 Decode Fast Copy serere reini a E A A OR E OEE a a L Eae 175 Using Initia
189. eesaegeedeacuaseadatasvaudannadeasdsapen E E S 103 XML Attribute Declarations esseseseeeeeseeeseesseesseeesersseerseseesetesseesseeeseeeseeessresseesse 104 Xsdiany Attrib te ooreis ieie sat a EEE E A EEEE A EE EEE EN 105 KSCSIMPIECOMENC senio nenne E R E A 106 RSACOMPLEXCOMECME ecadedsscoadsesvadiarsavdanachevsdadavsveass EE AE S E S TE Niit 107 Substitution Groups seisis eeit iiien iE a E E ER e ERE 108 Generated C C H Source Code reese en eet aee EEE E E A raS 111 Header Ch File ni Denei ua a a N sea ews ewes 111 Generated C Source Files sinire sed tigahaevisalevencdassnchenashgvsaigavaraadebe tenesnseadeatederendeasbens 114 Maximum Lines per File sijcacissasceasnassbiaaisaziad ds geaataseguaeeesedcaansgeedtendugesccasenezaenayebaa 115 Use of the maxcfiles Option cysseciass serccsavnvaseisdcveesadusbacesdetenedesveyuastsesencseauadcedese tenes 115 Generated CHF TS ornini sees a ids deeds Ea I ER AERE EEEREN 116 Generated C C files and the compat Option sssesssesssssessssessessseesseersseeesseesseesseessees 118 Generated C files and the symbian Option ss sssssssesssessssseesseessressessseresseessseessresseessee 118 Writable Static Data miraio i inaenea a T aE E R E A E EEE IRE 118 Extern Linkage serne rnnt a A R E A E R herons 119 Generated Build Biles sisser e E EE a a aa Sh 120 Generated Makefile nensis shaeaasials tates ai a aug deus E S E a ES 120 Generated VC Project Files ciccyaicisueccesansaseasaigeaaeteanca
190. efine an enumerated bit string that specifies named con stants for different bit positions ASNIC provides support for this type by generating symbolic constants and optional macros that can be used to set clear or test these named bits These sym bolic constants equate the bit name to the bit number defined in the specification They can be used with the rtBitSet rtBitClear and rtBitTest run time functions to set clear and test the named bits In addition generated C code contains an enumerated constant added to the control class with an entry for each of the bit numbers These entries can be used in calls to the methods of the ASNI1CBitStr class to set clear and test bits 47 BIT STRING The genBitMacros command line option can be used to generate macros to set clear or test the named bits in a bit string structure These macros offer better performance then using the run time functions because all calculations of mask and index values are done at compile time However they can result in a large amount of additional generated code For example the following ASN 1 production NamedBS BIT STRING bitOne 1 bitTen 10 Would translate to the following if genBitMacros was specified Named bit constants define NamedBS_bitOne 1 define SET_BS3_ bitOne bs lt code to set bit gt define CLEAR_BS3_bitOne bs lt code to clear bit gt define TEST_BS3_bitOne bs lt code to test bit gt
191. elements and a pointer to hold an array of the refer enced data type a dynamic array e A structure containing an integer count of elements and a fixed sized array of the referenced data type a static array The linked list option is the default for constructed types An array is used for a sequence of prim itive types The allocation for the contents field of the array depends on how the SEQUENCE OF is specified in the ASN 1 definition If a size constraint is used a static array of that size is gener ated otherwise a pointer variable is generated to hold a dynamically allocated array of values The decoder will automatically allocate memory to hold parsed SEQUENCE OF data values The type used for a given SEQUENCE OF construct can be modified by the use of a configuration item The lt storage gt qualifier is used for this purpose The dynamicArray keyword can be used at the global module or production level to specify that dynamic memory i e a pointer is used for the array The syntax of this qualifier is as follows lt storage gt dynamicArray lt storage gt The array keyword is used to specify that a static array is to be generated to hold the data In this case if the SEQUENCE OF production does not contain a size constraint the maxSize attribute must be used to specify the maximum size of the array For example lt storage maxSize 100 gt array lt storage gt If maxSize is not specified and the ASN 1 production conta
192. en an contextual tag is provided more than once ASN E MULTDEF A choice tag has multiple definitions ASN E UNDEFVAL The referenced value is not defined or cannot be found ASN E INVTYPNAM ASN E UNDEFTAG The referenced type must be tagged in this context Invalid type name This is a parsing failure all type names must begin with an uppercase letter ASN E UNKNOWN Undocumented error occurred in routine A status value is provided with this error message to help locate the cause of the failure 267 ASNIC Error Messages Error Code Error Description ASN I NOCASE ASN E IMPFILOPN A case statement for the named object was not generated The compiler was unable to open the named import file ASN E IMPFILPAR The compiler was unable to parse the named imported module ASN E IMPNOTFOU The named type was not found in the import module as specified in the IMPORT statement ASN E INVCNSTRNT ASN W INVOBJNAM Invalid constraint specification Invalid object name The object name must begin with a lowercase letter ASN E SETTOOBIG Set contains more than 32 elements ASN E DUPLCASE This tag was used in a previous switch case statement ASN E AMBIGUOUS ASN E VALTYPMIS This indicates a general ambiguity in the specification such as multiple embedded extensible elements This indicates the value specified does not match the type it is
193. en the parser leaves a given element space Using the ex ample above these would occur after the parsing of a b and c are complete The name of the element is once again passed to the event handling callback function 3 contents methods A series of virtual methods are defined to pass all of the different types of primitive values that might be encountered when parsing a message see the event handler class definition below for a complete list 4 error This event will be fired when a parsing error occurs It will provide fault tolerance to the parsing process as it will give the user the opportunity to fix or ignore errors on the fly to allow the parsing process to continue These events are defined as unimplemented virtual methods in two base classes AsnINamedEventHandler the first 3 events and Asn ErrorHandler the error event These class es are defined in the asn CppEvtHndlr h header file The start and end element methods are invoked when an element is parsed within a constructed type The start method is invoked as soon as the tag length is parsed in a BER message or the preamble length is parsed in a PER message The end method is invoked after the contents of the field are processed The signature of these methods is as follows virtual void startElement const char name int index Os virtual void endElement const char name int index 0 The name argument is used pass the element name The index argument i
194. enced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each decode function generated is as follows asnlD_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows status asnlD_ lt name gt OSCTXT pctxt lt name gt pvalue ASNiTagType tagging int length In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable must be initialized using the rtInitContext run time function before use The pvalue argument is a pointer to a variable of the generated type that will receive the decoded data The tagging and length arguments are for internal use when calls to decod
195. encoded field will hold the data in encoded form 137 General Procedure for Ta ble Constraint Decoding For the above complete example the Invoke type s argument element will be decoded as one of the types in the SupportedAttributes information object set i e either as a VisibleString or INTEGER type If the SupportedAttributes information object set is extensible then the argument element may be of a type not defined in the set In this case the decoder will set the Asn Object encoded field as before but the Asn1Object decoded field will be NULL indicating the value is of an un known type A C program fragment that could be used to decode the Invoke example is as follows include Test h include file generated by ASNIC main In this case the type of the decoded argument can be determined by testing the key field value In the example as shown the SupportedAttributes information object set is not extensible therefore the type of the argument must be one of the two shown If the set were extensible indicated by a in the definition then it is possible that an unknown opcode could be received which would mean the type can not be determined In this case the original encoded message data would be OSOCTET msgbuf 1024 ASNITAG msgtag int msglen status step 1 logic to read message into msgbuf step 2 create decode buffer and msg data type ASNIBERDecodeBuffer de
196. encoding using a dynamic buffer This also illustrates using the getMsgCopy method to fetch a copy of the encoded message include employee h include file generated by ASNIC main OSOCTET msgptr int msglen construct encodeBuffer class with no arguments ASNIBEREncodeBuffer encodeBuffer ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ encodeBuffer msgData populate msgData structure msgData name SMITH call Encode method if msglen employee Encode gt 0 encoding successful get copy of message msgptr encodeBuffer getMsgCopy delete msgptr free the dynamic memory else error processing Encoding a Series of Messages Using the C Control Class Interface A common application of BER encoding is the repetitive encoding of a series of the same type of message over and over again For example a TAP3 batch application might read billing data out of a database table and encode each of the records for a batch transmission If a user was to repeatedly instantiate and destroy the C objects involved in the encoding of a message performance would suffer This is not necessary however because the C objects can be reused to allow multiple messages to be encoded As example showing how to do this is as follows include employee h include file generated by ASNI1C main const OSOCTET msgptr OSOCTET m
197. enerate a common name for the new temporary type that can be used for other similar references The form of this common name is as follows _SeqOf lt elementProdName gt So instead of this SomePDU addresses SEQUENCE OF AliasAddress The following equivalent type would be generated _SeqOfAliasAddress SEQUENCE OF AliasAddress The advantage is that the new type can now be easily reused if SEQUENCE OF AliasAddress is used in any other element declarations Note the illegal use of an underscore in the first position This is to ensure that no name collisions occur with other ASN 1 productions defined within the specification Some SEQUENCE OF elements in constructed types are inlined In other words no temporary type is created instead either the osrtpList reference for linked list or the array definition is inserted directly into the generated C structure This is particularly true when XSD files are being compiled SET OF The ASN 1 SET OF type is converted into a C or C structured type that is identical to that for SEQUENCE OF as described in the previous section CHOICE The ASN 1 CHOICE type is converted into a C or C structured type containing an integer for the choice tag value t followed by a union u of all of the equivalent types that make up the CHOICE elements The tag value is simply a sequential number starting at one for each alternative in the CHOICE A define const
198. entries from the referenced Information Object Set are used in a union structure in much the same way as is done in a CHOICE construct If code is being generated from an XML schema file and the file contains an lt xsd any gt wildcard declaration a special type of any structure is inserted into the generated C C code This is the type OSXSDAny which is defined in the osSysTypes h header file This structure contains a union which contains alternatives for data in either binary or XML text form This makes it possible to transfer data in either binary form if working with binary encoding rules or XML form if working with XML Character String Types All 8 bit character character string types are derived from the C character pointer const char base type This pointer is used to hold a null terminated C string for encoding decoding For en coding the string can either be static i e a string literal or address of a static buffer or dynamic The decoder allocates dynamic memory from within its context to hold the memory for the string This memory is released when the rtxMemrree function is called The useful character string types in ASN 1 are as follows UTF8String UNIVERSAL 12 IMPLICIT OCTET STRING NumericString UNIVERSAL 18 IMPLICIT IA5String PrintableString UNIVERSAL 19 IMPLICIT IA5String T6lString TS U
199. eps 1 2 and 3 instantiate an instance of the XER decoding classes This example specifies an XML file as the message input source ASN1T_PersonnelRecord employee ASN1XERDecodeBuffer decodeBuffer filename ASN1C_PersonnelRecord employeeC decodeBuffer employee step 4 invoke the decode method stat employeeC Decod Lae 226 Procedure for Interfacing with Oth er C and C X ML Parser Libraries if 0 stat employeeC Print employee else decodeBuffer printErroriInfo step 5 dynamic memory is released when employeeC and decode buffer objects go out of scope return stat Procedure for Interfacing with Other C and C X ML Parser Libraries As mentioned previously the Expat XML Parser library is the default XML parser library imple mentation used for decoding XER messages It is also possible to use the C SAX handlers gen erated by ASNIC with other XML parser library implementations The XER Run Time Library ASNIXER provides a common interface to other parsers via a common adapter interface layer There is a special XML interface object file for each of the following supported XML parsers e rtXmlLibxml2IF interface to LIBXML2 e rtXmlXercesIF interface to XERCES e rtXmlExpatIF interface to EXPAT e rtXmlMicrolF interface to custom small footprint microparser The XER Run Time Library is completely independent from the XML reade
200. er NewElement fill_Name amp pChildInfo gt name Ralph T Smith pChildiInfo gt dateOfBirth 19571111 listHelper Append pChildInfo In this example msgData is an instance of the main PDU class being encoded PersonnelRecord This object contains an element called children which is a linked list of chilainformation records 63 SEQUENCE OF The code snippet illustrates how to use the generated control class for the list to allocate a record populate it and append it to the list ASNIC also generates helper methods in SEQUENCE SET and CHOICE control classes to as sist in allocating and adding elements to inline SEQUENCE OF lists These methods are named new_ lt elem gt _element and append_to_ lt elem gt where lt elem gt would be replaced with the name of the element they apply to Generation of Temporary Types for SEQUENCE OF Ele ments As with other constructed types the lt type gt variable can reference any ASN 1 type including other ASN 1 constructed types Therefore it is possible to have a SEQUENCE OF SEQUENCE SE QUENCE OF CHOICE etc When a constructed type or type that maps to a C structured type is referenced a temporary type is generated for use in the final production The format of this temporary type name is as follows lt prodName gt _element In this definition lt prodName gt refers to the name of the production containing the SEQUENCE OF type For example a simple
201. er to that it can be parsed again in the PDU decode function rtXmlpMarkLastEventActive amp ctxt 235 Generated C Decode Method Format and Calling Parameters step 4 call the decode function stat XmlDec_PersonnelRecord_PDU amp ctxt amp data if stat 0 process received data else error processing rtxErrPrint amp ctxt can check for other possible tag matches here step 5 free the context rtFreeContext amp ctxt Generated C Decode Method Format and Calling Parameters Generated decode functions are invoked through the class interface by calling the base class Decode or DecodeFrom methods The calling sequence for this method is as follows status lt object gt Decod ps In this definition lt object gt is an object of the class generated for the given production An OSXMLDecodeBuffer object must be passed to the lt object gt constructor prior to decoding This is where the message stream containing the XML document to be decoded is specified Several constructors are available allowing the specification of XML input from a file memory buffer or another stream The function result variable status returns the status of the decode operation The return status will be zero if decoding is successful or a negative value if an error occurs Return status values are documented in the C C Common Functions Reference Manual a
202. er_a lib multithreading and MD dynamic link libraries options asnlper_a lib A asnlxer_a lib These are not thread safe However they provide the smallest asnixml_a lib footprint of the different libraries asnirt lib DLL libraries These are used to link against the DLL versions asnlber lib asnlper lib asnlxer lib asnlxml lib of the run time libraries asn rt dll etc asnletme alib Static multi threaded libraries These libraries were built with the E ee MT option They should be used if your application contains asnlxermt_a lib threads and you wish to link with the static libraries The DLLs asnlxmlmt_a lib are also thread safe In Visual Studio 2005 and greater all libraries are multi threaded by default so these libraries are not available for those versions asnirtmd_a lib DLL ready multi threaded libraries These libraries were built asnlbermd_a lib denicem a iib with the MD option They allow linking additional object mod asnlxermd_a lib ules in with the ASNIC run time modules to produce larger asnlxmlmd_a lib DLLs For dynamic linking on UNIX Linux a shared object version of each run time library is included in the lib subdirectory This file typically has the extension so for shared object or sl for shared library See the documentation for your UNIX compiler to determine how to link using these files Compiling and linking code generated to support the XML encoding rules XER is mo
203. erated by ASNIC const char filename message dat Step 1 Initialize the context and stream if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 stat rtxStreamFileCreateWriter amp ctxt filename if stat 0 rtxErrPrint amp ctxt return stat for 7 Step 2 Populate the structure to b ncoded mployee name SMITH Step 3 Call the generated encode function stat asnlBSE_Employee amp ctxt amp employee ASN1EXPL Step 4 Check the return status and break the loop if error occurs if stat 0 error processing break Step 5 Close the stream rtxStreamClose amp ctxt Generated Streaming C Encode Method For mat and Calling Parameters C code generation of stream based encoders is selected by using the c and stream com piler command line options In this case ASN1C generates an EncodeTo method that wraps the C function call This method provides a more simplified calling interface because it hides things such as the context structure and tag type parameters 161 Generated Streaming C Encode Method Format and Calling Parameters The calling sequence for the generated C class method is as follows stat lt object gt EncodeTo lt outputStream gt
204. ere generated for all types This default behavior can be overridden by using a configuration file entry or the pdu command line switch to explicitly declare the PDU types The lt isPDU gt flag is used to declare a type to be a PDU in a configuration file An example of this is as follows lt asnlconfig gt lt module gt lt name gt H323 MESSAGES lt name gt lt production gt lt name gt H323 UserInformat ion lt name gt lt isPDU gt lt production gt 125 XER Class Definition lt module gt lt asnlconfig gt This will cause only a single ASN C_ control class definition to be added to the generated code for the H323 UserInformation production If the module contains no PDUs i e contains support types only the lt noPDU gt empty element can be specified at the module level to indicate that no control classes should be generated for the module XER Class Definition For the XML encoding rules XER the generated class definition is as follows class ASN1C_ lt name gt public ASN1CType protected ASN1XERSAXHandler ASN1T_ lt name gt amp msgData additional control variables public ASN1C_ lt name gt ASN1C_ lt name gt ASN1MessageBufferIF amp msgBuf ASN1IT_ lt name gt amp data standard int Encode int Decode ASNIT_ lt name gt amp data ncode decode methods defined in ASN1CType base class Qi Qi ncode decode method
205. ersion of ASN1C contains logic to parse some common MACRO definitions that are still in widespread use despite the fact that MACRO syntax was retired with this version of the standard The types of MACRO definitions that are supported are ROSE OPERATION and ERROR and SNMP OBJECT TYPE ROSE OPERATION and ERROR ROSE stands for Remote Operations Service Element and defines a request response transaction protocol in which requests to a conforming entity must be answered with the result or errors defined in operation definitions Variations of this are used in a number of protocols in use today including CSTA and TCAP The definition of the ROSE OPERATION MACRO that is built into the ASNIC is as follows OPERATION MACRO BEGIN TYPE NOTATION Parameter Result Errors LinkedOperations VALUE NOTATION value VALUE INTEGER Parameter ArgKeyword NamedType empty ArgKeyword ARGUMENT PARAMETER Result RESULT ResultType empty Errors ERRORS ErrorNames empty LinkedOperations LINKED LinkedOperationNames empty ResultType NamedType empty ErrorNames ErrorList empty ErrorList Error ErrorList Error Error value ERROR shall reference an error value type shall reference an error type if no value is specified LinkedOperationNames OperationList emp
206. es A param eterized type is used as a shorthand notation to pass an information object set into a container type The container type holds a list of the IE fields The structure of an IE field type is similar to a mes sage type the first element is used as an index element to the remaining elements That is followed by one or more fixed type or variable type elements In the case defined above only a single fixed type and variable type element is shown but there may be more An example of this pattern from the S1AP LTE specification follows HandoverRequired SEQUENCE protocollEs ProtocollIE Container HandoverRequiredIEs ProtocollIE Container S1AP PROTOCOL IES IEsSetParam SEQUENCE SIZE 0 maxProtocollIEs OF ProtocolIE Field IEsSetParam ProtocolIE Field S1AP PROTOCOL IES IEsSetParam SEQUENCE id S1AP PROTOCOL IES amp id IEsSetParam criticality S1AP PROTOCOL IES amp criticality IEsSetParam id value S1AP PROTOCOL IES amp Value IEsSetParam id In this case standard parameterized type instantiation is used to create a type definition for the protocollEs element This results in a list type being generated List of HandoverRequired_protocollEs_element 84 Unions Table Constraint Model typedef OSRTDList HandoverRequired_protocollEs
207. es an a R E REEE EE RE E 269 ASN l specific Status Messages syscisscacdtiaveasssdyeadsasuaccesdigsenatsauegacessddaedenlocsaaselpeincdeaoneaents 277 vii viii Overview of ASN1C The ASNIC code generation tool translates an Abstract Syntax Notation 1 ASN 1 or XML Schema Definitions XSD source file into computer language source files that allow ASN 1 da ta to be encoded decoded This release of the compiler includes options to generate code in four different languages C C C or Java This manual discusses the C and C code generation capabilities The ASNIC Java User s Manual discusses the Java code generation capability The ASNIC C User s Manual discusses the C code generation capability Each ASN 1 module that is encountered in an ASN 1 source file results in the generation of the following two types of C C language files 1 An include h file containing C C typedefs and classes that represent each of the ASN 1 productions listed in the ASN 1 source file and 2 A set of C C source c or cpp files containing C C encode and decode functions One encode and decode function is generated for each ASN 1 production The number of files gen erated can be controlled through command line options These files when compiled and linked with the ASN 1 low level encode decode function library provide a complete package for working with ASN 1 encoded data ASNIC works with the version of ASN 1 specified in
208. es the object identifiers and data that are contained in the MIB The version of the MACRO currently supported by this version of ASNIC can be found in the SMI Version 2 RFC RFC 2578 The compiler generates code for two of the items specified in this MACRO definition 1 The ASN 1 type that is specified using the SYNTAX command and 2 The assigned OBJECT IDENTIFIER value For an example of the generated code we can look at the following definition from the UDP MIB udpInDatagrams OBJECT TYPE SYNTAX Counter32 MAX ACCESS read only STATUS current DESCRIPTION The total number of UDP datagrams delivered to UDP users 264 SNMP OBJECT TYPE udp 1 In this case a type definition is generated for the SYNTAX element and an Object Identifier value is generated for the entire item The name used for the type definition is lt name gt _SYNTAX where lt name gt would be replaced with the OBJECT TYPE name i e udpInDatagrams The name used for the Object Identifier value constant is the OBJECTTYPE name So for the above definitions the following two C items would be generated typedef Counter32 udpInDatagrams_SYNTAX ASN1OBJID udpInDatagrams 8 1 3 6 1 2 1 7 1 265 266 Appendix A Runtime Status Codes This appendix describes status code messages returned by the ASNIC C C runtime libraries When deploying applications linked against optimized runtime lib
209. es would cause different integer types to be used that provide the most efficient amount of storage The following table shows the types that would be used for the different range values Min Lower Bound Max Upper Bound ASNIC Type C Type 128 127 OSINTS char signed 8 bit int 0 255 OSUINT8 unsigned char un signed 8 bit number 32768 32767 OSINT16 short signed 16 bit int 0 65535 OSUINT16 unsigned short un signed 16 bit int 2147483648 2147483647 OSINT32 int signed 32 bit inte ger 0 4294967295 OSUINT32 unsigned int unsigned 32 bit integer The C type that is used to represent a given integer value can also be altered using the lt ctype gt configuration variable setting This allows any of the integer types above to be used for a given integer type as well as a 64 bit integer type The values that can be used with lt ctype gt are byte int16 uint16 int32 uint32 and int64 An example of using this setting is as follows Suppose you have the following integer declaration in your ASN 1 source file MyIntType APPLICATION 1 INTEGER You could then have ASNIC use a 64 bit integer type for this integer by adding the following declaration to a configuration file to be associated with this module lt production gt lt name gt My Int Type lt name gt lt intCType gt int 64 lt intCType gt lt production gt The lt intctType gt setting is also available at the module l
210. essing This will also not work if the message buffer is an automatic variable in a function and the decoded result type is being passed out The result type variable will point at data in the buffer variable that has gone out of scope To set fast copy the rtSetFastCopy function must be invoked with the initialized context variable that will be used to decode a message This should be done once prior to entering the loop that will be used to decode a stream of messages Using Initialization Functions Initialization functions are generated by the ASN1C compiler when the gen nit option is added to the ASN1C command line These functions can be used as an alternative to memset ing a variable to zero to prepare it to receive decoded data The advantage is that the initialization functions are smarter and know exactly what within the structures needs to be zeroed as opposed to blindly clearing everything So for example large byte arrays used to hold OCTET STRING data will not be zeroed This can add up to significant performance improvements in the long run particular in complex deeply nested ASN 1 types If initialization functions are generated the generated decode logic will use them wherever it can in place of calls to zero memory BER DER Deferred Decoding Another way to improve decoding performance of large messages is through the use of deferred decoding This allows for the selective decoding of only parts of a message in a sing
211. esults in the following C type typedef struct EXTERN MyType List of const OSUTF8CHAR OSRTDList attr MyType To populate a variable of this type for encoding one would add name value strings to the list for each attribute For example MyType myVar rtxDListInit amp myVar attr rtxDListAppend amp ctxt amp myVar attr OSUTF8 attrl valuel rtxDListAppend amp ctxt amp myVar attr OSUTF8 attr2 value2 and so on 105 xsd simpleContent xsd simpleContent The xsd simpleContent type is used to either extend or restrict an existing simple type definition In the case of extension the common use is to add attributes to a simple type ASN1C will generate a C structure in this case with an element called base that is of the simple type being extended An example of this is as follows lt xsd complexType name SizeType gt lt xsd simpleContent gt lt xsd extension base xsd integer gt lt xsd attribute name system type xsd token gt lt xsd extension gt lt xsd simpleContent gt lt xsd complexType gt this results in the following generated C type definition typedef struct EXTERN SizeType struct unsigned system_Present 1 m const OSUTF8CHAR system_ OSINT32 base SizeType In this case the attribute system was added first note the name change to system_ which was the result of system being determin
212. etBuffer amp ctxt msgbuf msglen aligned if stat asnlPE_Employee amp ctxt amp employee 0 msglen pe_GetMsgLen amp ctxt else error processing In general static buffers should be used for encoding messages where possible as they offer a substantial performance benefit over dynamic buffer allocation The problem with static buffers however is that you are required to estimate in advance the approximate size of the messages you will be encoding There is no built in formula to do this the size of an ASN 1 message can vary widely based on data types and other factors If performance is not a significant issue then dynamic buffer allocation is a good alternative Set ting the buffer pointer argument to NULL in the call to pu_setBuffer specifies dynamic allocation This tells the encoding functions to allocate a buffer dynamically The address of the start of the message is obtained after encoding by calling the run time function pe_GetMsgPtr The following code fragment illustrates PER encoding using a dynamic buffer 189 Procedure for Using the C Control Class Encode Method include employee h include file generated by ASNIC main OSOCTET msgptr int msglen stat OSCTXT ecxt OSBOOL aligned TRUE Employee employee typedef generated by ASNIC mployee name givenName SMITH stat rtInitContext amp ctxt if stat 0 p
213. evel to specify that the given C integer type be used for all unconstrained integers within the module Large Integer Support In C and C the maximum size for an integer type is normally 64 bits or 32 bits on some old er platforms ASN 1 has no such limitation on integer sizes and some applications security key 44 BIT STRING values for example demand larger sizes In order to accommodate these types of applications the ASNIC compiler allows an integer to be declared a big integer via a configuration file variable the lt isBigInteger gt setting is used to do this see the section describing the configuration file for full details When the compiler detects this setting it will declare the integer to be a character string variable instead of a C int or unsigned int type The character string would then be populated with a character string representation of the value to be encoded Supported character string repre sentations are hexadecimal strings starting with Ox octal strings starting with 0o and decimal no prefix For example the following INTEGER type might be declared in the ASN 1 source file SecurityKeyType APPLICATION 2 INTEGER Then in a configuration file used with the ASN 1 definition above the following declaration can be made lt production gt lt name gt SecurityKeyType lt name gt lt isBigInteger gt lt production gt This will cause the compiler to generate the f
214. f a type that is not in the defined set In this case if the index element value is outside the information object set then the argument element will be assumed to be an Asn OpenType The Invoke type encode function call will use the value from argument encoded data field i e it will have to be pre encoded because the encode function will not be able to determine from the table constraint how to encode it A C program fragment that could be used to encode an instance of the Invoke type is as follows include TestTable h include file generated by ASNI1C main const OSOCTET msgptr OSOCTET msgbuf 1024 int msglen step 1 construct ASNIC C generated class this specifies a static encode message buffer ASNIBEREncodeBuffer encodeBuffer msgbuf sizeof msgbuf 135 General Procedure for Ta ble Constraint Encoding step 2 populate msgData structure with data to be encoded ASN1T_Invoke msgData ASN1C_Invoke invoke encodeBuffer msgData msgData opcode numids 3 msgData opcode subid 0 0 msgData opcode subid 1 1 msgData opcode subid 2 1 ASN1VisibleString argument objsys msgData argument decoded void amp argument note opcode value is 0 1 1 so argument must be ASN1VisibleString type step 3 invoke Encode method if msglen invoke Encode gt 0 encoding successful get pointer to start
215. fault but may be added when users need to free specific types individually instead of relying on ASNI1C s built in memory management functions Bit macro functions may also be generated for setting clearing and testing bits in BIT sTRING productions Table constraints in C C were modified for ASNIC version 6 2 to make their data structures easier to manipulate The table unions option causes a cxorce like union structure to be generated for information object classes In practice the generated code is more compact easier to read and confers several advantages for developers principally type safety and readability The Generate static elements option is used to add static elements to corce constructs instead of pointer values Using fully qualified enumerated types will cause ASN1C to emit enumerated types prefixed by their parent module name Enumerated types are often reused in different modules and ASN IC s automatic name resolution is usually insufficient to disambiguate which type is which This option only needs to be selected in C since C enumerations are contained in classes The other options are described in greater detail in Running ASNIC from the command line 28 Compilation C C Code Generation Options Code Modifications Makefiles and Projects E Generate Makefiles E Generate Visual Studio Project Generate Libraries E Link applications using shared libraries The preceding
216. fication of a C or C source c or cpp file to which generated copy functions will be written Copy functions allow a copy to be made of an ASNIC generated vari able For C they cause copy constructors and assignment operators to be added to generated classes The lt filename gt argument to this option is op tional If not specified the functions will be written to lt modulename gt Copy c where lt mod ulename gt is the name of the module from the ASN 1 source file genFree None This option instructs the compiler to generate a memory free function for each ASN 1 produc tion Normally memory is freed within ASNIC by using the rtxMemFree run time function to free all memory at once that is held by a context Generated free functions allow finer grained control over memory freeing by just allowing the memory held for specific objects to be freed genMake lt filename gt This option instructs the compiler to generate a portable makefile for compiling the generat ed C or C code If used with the w32 com mand line option a makefile that is compatible with the Microsoft Visual Studio nmake utility is generated otherwise a GNU compatible make file is generated Note that the nmake option may now be used instead of the make w32 combination to pro duce a Visual Studio makefile genMakeDLL lt filename gt This option instructs the compiler to generate a portable makefile for
217. file a C encode function is generated This function will convert a populated C variable of the given type into an encoded ASN 1 message If C code generation is specified a control class is generated that contains an Encode method that wraps this function This function is invoked through the class interface to convert a populated msgData attribute variable into an encoded ASN 1 message Generated C Function Format and Calling Pa rameters The format of the name of each generated encode function is as follows asnlE_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each encode function is as follows len asnlE_ lt name gt OSCTXT pctxt lt name gt pvalue ASN1TagType tagging In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asyn chronous or threaded application The user is required to supply a po
218. further control of the compilation process They are optional and are only needed if the default compilation process is to be altered for example if a type prefix is to be added to a generated type name See the Compiler Configuration File section for details on defining these files Common Code Generation Options Code generation options common to all language types are specified in the following tabbed win dow 23 Common Code Generation Options Input File Type Modern ASN 1 1997 based on X 680 standard Legacy ASN 1 based on obsolete X 208 standard with ROSE or SNMP macros E Lax Syntax Check Additional Translations V Generate equivalent XML schema XSD file Application Language Type c C None syntax check only Encoding Rules F BER DER CER select aligned or unaligned PER at run time Code Options F Generate code for all dependent imported type definitions E Generate code compatible with compiler version Language options pictured above encompass not only the output language choice but also input specification type encoding rules and code compatibility options Certain options will be inactive greyed out depending on the file type selected For example if an XSD file is selected the option Generate ASN 1 file based on X 694 will be active and the option Generate equivalent XML schema XSD file will be inactive Checking Generate code for all dependent importe
219. gativelnteger INTEGER MIN 1 NMTOKEN UTF8String NMTOKENS SEQUENCE OF UTF8String nonNegativelnteger INTEGER 0 MAX nonPositiveInteger INTEGER MIN 0 normalizedString UTF8String positiveInteger INTEGER 1 MAX short INTEGER 32768 32767 string UTF8String time UTF8String token UTF8String unsignedByte INTEGER 0 255 unsignedShort INTEGER 0 65535 unsignedInt INTEGER 0 4294967295 unsignedLong INTEGER 0 1844674407370955 1615 The C C mappings for these types can be found in the section above on ASN 1 type mappings XSD Complex Types XSD complex types and selected simple types are mapped to equivalent ASN 1 constructed types In some cases simplifications are done to make the generated code easier to work with The fol lowing are mappings for specific XSD complex types xsd sequence The XSD sequence type is normally mapped to an ASN 1 SEQUENCE type The following items describe special processing that may occur when processing a sequence definition e If the resulting SEQUENCE type contains only a single repeating element it is converted into a SEQUENCE OF type This can occur if either the sequence declaration has a maxOccurs 98 xsd all attribute with a value greater than one or if the single element inside has a similar maxOccurs attribute e Ifthe sequence contains an element that has a minOccurs 0 attribute declaration the element is mapped to be an OPTIONAL
220. ge msgptr xe_getp amp ctxt 153 Generated C Encode Method Format and Calling Parameters do something with th ncoded message else error processing Call rtxMemReset to reset the memory heap for the next iteration Note all data allocated by rtxMemAlloc will become invalid after this call rtxMemReset amp ctxt rtFreeContext amp ctxt The rtxMemReset call does not free memory instead it marks it as empty so that it may be reused in the next iteration Thus all memory allocated by rtxMemAlloc will be overwritten and data will be lost Generated C Encode Method Format and Calling Parameters When C code generation is specified the ASN1C compiler generates an Encode method in the generated control class that wraps the C function call This method provides a more simplified calling interface because it hides things such as the context structure and the tag type parameters The calling sequence for the generated C class method is as follows len lt object gt Encode In this definition lt object gt is an instance of the control class i e ASN1C_ lt prodName gt generated for the given production The function result variable len returns the length of the data actually encoded or an error status code if encoding fails Error status codes are negative to tell them apart from length values Return status values are defined in the asn type h include file
221. generate code to save restore unknown extensions and Do not generate types for items embedded in information objects may all be used to reduce the amount of generated code Generate compact code cannot be used in conjunction with Generate compatible code If XML validation is not needed check Do not generate XML namespaces for ASN 1 modules This will result in a smaller codebase as well as smaller output XML data Check Generate short form of type names if generated type names are too long for the target language The following tab provides options for generating utility functions and applications Common Code Generation Options l Language Options Function Options Utility Options Sample Program Generation l Generate writer sample program writer Generate reader sample program reader Generate code for populating data structures test rotocol Data Units PDUs Treat all types as Protocol Data Units PDU s pdu Specify a PDU for the sample programs usepdu bugging and Event Handlers Generate code to invoke event handler callback functions events Generate pure parser event handler callbacks with no types notypes Add tracing diagnostic messages to code trace Other Options V Automatically create unique names for duplicate items Do not add date stamp to generated files nodatestamp Enter command ine options not available in GUI The Sample Program Generation frame allows you
222. generated EncodeTo and De codeFrom methods in the PDU control class are set up to encode complete XML documents in cluding the start document header as well as namespace attributes in the main element tag Generated encode functions are invoked through the class interface by calling the base class Encode method The calling sequence for this method is as follows stat lt object gt Encode In this definition lt object gt is an object of the class generated for the given production The function result variable stat returns the status value from the XML encode function This status value will be zero if encoding was successful or a negative error status value if encoding fails Return status values are defined in the rtxErrCodes h include file The user must call the encode buffer class methods getMsgPtr and getMsgLen to obtain the starting address and length of the encoded message component Procedure for Using the C Control Class En code Method The procedure to encode a message using the C class interface is as follows 231 Procedure for Using the C Control Class Encode Method Instantiate an XML encode buffer object OSXMLEncodeBuffer to describe the buffer into which the message will be encoded Constructors are available that allow a static message buffer to be specified The default constructor specifies use of a dynamic encode buffer Instantiate an ASNIT_ lt type gt object and populate it with da
223. generated for each corresponding ASN 1 source file lt directory gt This option is used to specify a directory that the compiler will search for ASN 1 source files for IMPORT items Multiple I qualifiers can be used to specify multiple directories to search java None Generate Java source code See the ASNIC Java User s Guide for more information on Java code generation lax None This option instructs the compiler to not gener ate code to check constraints When used in con junction with the compact option it produces the smallest code base for a given ASN 1 spec ification laxsyntax None This option instructs the compiler to not do a thorough syntax check when compiling a spec ification and to generate code even if the speci fication contains non fatal syntax errors Use of the code generated in this case can have unpre dictable results however if a user knows that certain parts of a specification are not going to be used this option can save time libdir lt directory gt This option is used in conjunction with the gen Make option to specify the name of the library directory to be added to the makefile linkedList none This option specifies that a linked list type is to be used for SEQUENCE OF SET OF constructs list None Generate listing This will dump the source code to the standard output device as it is parsed This can be useful for finding
224. generation was done 178 Generated Streaming C Function Format and Calling Parameters Before any decode function can be called the user must first initialize a context variable This is a variable of type OSCTXT This variable holds all of the working data used during the decoding of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished by using the berStr mlnitContext function OSCTXT ctxt context variable if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 The next step is to create a stream object within the context This object is an abstraction of the output device to which the data is to be encoded and is initialized by calling one of the following functions e rtxStreamFileOpen e rtxStreamFileAttach e rtxStreamSocketAttach e rtxStreamMemoryCreate e rtxStreamMemoryAttach The flags parameter of these functions should be set to the OSRTSTRMF_INPUT constant value to indicate an input stream is being created see the C C Common Run Time Library Reference Manual for a full description of these functions A simplified version of the Open functions are the CreateReader functions e rtxStreamFileCreateReader e rtxStreamMemoryCreateReader e rtxStreamSocketCreateRe
225. ginal status is passed out which forces the termination of the decoding process 255 How to Use It The full text of the handler is as follows int MyErrorHandler error OSCTXT pCtxt ASNICCB pCCB int stat This handler is set up to look explicitly for ASN_E_NOTINSET errors because we know the SET might contain some bogus elements if stat ASN_E_NOTINSET Print information on the error that was encountered printf decod rror detected n rtErrPrint pCtxt printf n Skip element xd_NextElement pCtxt Return an OK status to indicate parsing can continue return 0 else return stat pass existing status back out Now we need to register the handler Unlike event handlers only a single error handler can be registered The method to do this in the message buffer class is setErrorHandler The following two lines of code in the reader program register the handler MyErrorHandler errorHandler decodeBuffer setErrorHandler amp errorHandler The error handlers can be as complicated as you need them to be You can use them in conjunction with event handlers in order to figure out where you are within a message in order to look for a specific error at a specific place Or you can be very generic and try to continue no matter what Example 3 A Pure Parser to Convert PER encoded Data to XML A pure parser is created by using th
226. greater than or equal to zero This would determine if a x should be appended to the element name In the sample program that is included with the compiler distribution the implementation is complete In endElement we simply terminate our brace block as follows void PrintHandler endElement const char name int index mIndentLevel indent printf n Next we need to create an object of our derived class and register it prior to invoking the decode method In the reader cpp program the following lines do this Create and register an event handler object PrintHandler pHandler new PrintHandler employee decodeBuffer addEventHandler pHandler The addEventHandler method defined in the Asn MessageBuffer base class is the mechanism used to do this Note that event handler objects can be stacked Several can be registered before invoking the decode function When this is done the entire list of event handler objects is iterated through and the appropriate event handling callback function invoked whenever a defined event is encountered The implementation is now complete The program can now be compiled and run When this is done the resulting output is as follows employee name givenName John initial pr familyName Smith This can certainly be improved For one thing it can be changed to print primitive values out in a name value
227. gument to zero An encode function can then be called to encode the message If the return status indicates success 0 then the message will have been encoded in the given buffer or written to the given stream OER encoding starts from the beginning of the buffer and proceeds from low memory to high memory until the message is complete This differs from definite length BER where encoding was done from back to front Therefore the buffer start address is where the encoded OER message begins The length of the encoded message can be obtained by calling the rtxCtxtGetMsgLen run time function If dynamic encoding was specified i e a buffer start address and length were not given the rtxCtxtGetMsgPtr run time function can be used to obtain the start address of the message This routine will also return the length of the encoded message If a memory stream was used the message start address and length can be obtained by calling the rtxStreamMemoryGetBuffer function A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC 202 Procedure for Calling C Encode Functions main PersonnelRecord employee OSCTXT EET OSOCTET msgptr int i len stat const char filename message dat Populate employee C structure asnlInit_PersonnelRecord amp employee mployee name givenName SMITH Initialize context
228. h the tables op tion When the tables command line option is used additional code is generated to support the addi tional processing required to verify table constraints This code varies depending on whether C or C code generation is selected The C code is designed to take advantage of the object oriented capabilities of C These capabilities are well suited for modeling the behavior of information objects in practice The following subsections describe the code generated for each of these lan guages The code generated to support these constraints is intended for use only in compiler generated code Therefore it is not necessary for the average user to understand the mappings in order to use 131 Additional Code Generat ed with the tables option the product The information presented here is informative only to provide a better understanding of how the compiler handles table constraints C Code Generation For C code is generated for the Information Object Sets defined within a specification in the form of a global array of structures Each structure in the array is an equivalent C structure representing the corresponding ASN 1 information object Additional encode and decode functions are also generated for each type that contains table con straints These functions have the following prototypes BER DER int asnlETC_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue int asnl
229. hat point on that memory is reused thereby making dynamic memory allocation a negligent issue in the overall performance of the decoder A more detailed explanation of these functions and other memory management functions can be found in the C C Common Run Time Library Reference Manual Compact Code Generation Using the compact code generation option compact and lax validation option ax can also improve decoding performance The compact option causes code to be generated that contains no diagnostic or error trace mes sages In addition some status checks and other non critical code are removed providing a slightly less robust but faster code base 174 Decode Fast Copy The ax option causes all constraint checks to be removed from the generated code Performance intensive applications should also be sure to link with the compact version of the base run time libraries These libraries can be found in the ib_opt for optimized subdirectory These run time libraries also have all diagnostics and error trace messages removed as well as some non critical status checks Decode Fast Copy Fast Copy is a special run time flag that can be set for the decoder that can substantially reduce the number of copy operations that need to be done to decode a message The copy operations are reduced by taking advantage of the fact that the data contents of some ASN 1 types already exist in decoded form in the message buffer
230. he destructor of an ASNITPDU inherited class is called The example above will work correctly without any modifications in this case Another way to keep data is to make a copy of the decoded object before it goes out of scope A method called newCopy is also generated in the control class for these types which can be used to create a copy of the decoded object This copy of the object will persist after the control class and message buffer objects are deleted The returned object can be deleted using the standard C delete operator when it is no longer needed 144 Populating Generated Struc ture Variables for Encoding Returning to the example above it can be made to work if the type being decoded is a PDU type by doing the following ASNI1T_ lt type gt func2 ASN1T_ lt type gt msgdata ASNIBERDecodeBuffer decbuf ASN1C_ lt type gt cc decbuf msgdata cc Decode Use newCopy to return a copy of the decoded item return cc newCopy Populating Generated Structure Variables for Encoding Prior to calling a compiler generated encode function a variable of the type generated by the com piler must be populated This is normally a straightforward procedure just plug in the values to be encoded into the defined fields However things get more complicated when more complex constructed structures are involved These structures frequently contain pointer types which means memory management issues mus
231. he name of each generated C XER decode function is as follows asnlXD_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows status asnlXD_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so that it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable must be initialized using the rtInitContext run time function before use C XER decoding is stream oriented To perform streaming operations the context pointer pctxt must also be initialized as a stream by using the rtxStreamInit run time library function see the C C Common Run Time Library Reference Manual for a description of the run time stream C functions The pvalue argument is a p
232. hed by calling the xd_setp run time library function This function takes as an argument the start address of the message to be decoded The function returns the starting tag value and overall length of the message This makes it possible to identify the type of message received and apply the appropriate decode function to decode it A decode function can then be called to decode the message If the return status indicates success the C variable that was passed as an argument will contain the decoded message contents Note that the decoder may have allocated dynamic memory and stored pointers to objects in the C structure After processing on the C structure is complete the run time library function rtxMemFree should be called to free the allocated memory A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main OSOCTET msgbuf 1024 ASNITAG msgtag int msglen OSCTXT CURE PersonnelRecord employee logic to read message into msgbuf Step 1 Initialize a context variable for decoding if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 xd_setp amp ctxt msgbuf 0 amp msgtag amp msglen Step 2 Test message tag for type of message received note this is optional the decode
233. hich the declared elements are expected to be in the given order If an element is encoun tered that is not the one expected this error is raised Invalid enumerated identifier This status is re turned when an enumerated value is being en coded or decoded and the given value is not in the set of values defined in the enumeration facet RTERR_SETDUPL Duplicate element in set This status code is re turned when decoding an ASN 1 SET or XSD xsd all construct It is raised if a given element defined in the content model group occurs mul tiple times in the instance being decoded RTERR_SETMISRQ Missing required element in set This status code is returned when decoding an ASN 1 SET or XSD xsd all construct and all required elements in the content model group are not found to be present in the instance being decoded RTERR_NOTINSET Element not in set This status code is returned when encoding or decoding an ASN 1 SET or XSD xsd all construct When encoding it occurs 270 General Status Messages Error Code Error Name Description when a value in the generated _order member variable is outside the range of indexes of items in the content model group It occurs on the de code side when an element is received that is not defined in the content model group RTERR_SEQOVFLW Sequence overflow This status code is returned when decoding a repeating element ASN 1 SE QUENCE OF or
234. his function will parse the data contents from an OER encoded ASN 1 message and populate a variable of the corresponding type with the data Generated C Function Format and Calling Pa rameters The format of the name of each generated OER decode function is as follows OERDec_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows status OERDec_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The pvalue argument is a pointer to a variable to hold the decoded result This variable is of the type generated from the ASN 1 production The decode function will automatically allocate dyna
235. iables this type of error is commonly known as dangling pointers Using the second technique 1 e using C malloc and free can solve this problem In this case the memory for each of the elements can be safely freed after the encode function is called But the downside is that a free call must be made for each corresponding malloc call For complex structures remembering to do this can be difficult thus leading to problems with memory leaks The third technique uses the compiler run time library memory management functions to allocate and free the memory The main advantage of this technique as opposed to using C malloc and free is that all allocated memory can be freed with a single rtxMemFree call The rtxMemAlloc macro can be used to allocate memory in much the same way as the C malloc function with the only difference being that a pointer to an initialized OSCTXT structure is passed in addition to the number of bytes to allocate All allocated memory is tracked within the context structure so that when the rtxMemFree function is called all memory is released at once Accessing Encoded Message Components After a message has been encoded the user must obtain the start address and length of the message in order to do further operations with it Before a message can be encoded the user must describe the buffer the message is to be encoded into by specifying a message buffer start address and size There are three different types of mess
236. ic static list ar ray or dynamicArray keyword This variable allows a user to substitute a known binary PER encoding for the given element This encoding will be inserted into the encoded data stream on encoding and skipped over on decod ing Its purpose is the production of more com pact and faster code for PER by bypassing run time calculations needed to encode or decode variable data The definition is the same as for the global case except that the specified storage type will only be applied to the generated C or C type for this element Compiler Error Reporting Errors that can occur when generating source code from an ASN 1 source specification take two forms syntax errors and semantics errors 41 Compiler Error Reporting Syntax errors are errors in the ASN 1 source specification itself These occur when the rules spec ified in the ASN 1 grammar are not followed ASNIC will flag these types of errors with the error message Syntax Error and abort compilation on the source file The offending line number will be provided The user can re run the compilation with the 1 flag specified to see the lines listed as they are parsed This can be quite helpful in tracking down a syntax error The most common types of syntax errors are as follows e Invalid case on identifiers module name must begin with an uppercase letter productions types must begin with an uppercase letter and element names
237. ied in the ASN 1 definition 3 If the genCopy command line switch was specified a copy constructor will be generated to allow an instance of the data contained within a PDU control class object to be copied 4 Also if genCopy was specified a destructor is generated if the type contains dynamic fields This destructor will free all memory held by the type when the object is deleted or goes out of scope SET The ASN 1 SET type is converted into a C or C structured type that is identical to that for SEQUENCE as described in the previous section The only difference between SEQUENCE and SET is that elements may be transmitted in any order in a SET whereas they must be in the defined order in a SEQUENCE The only impact this has on ASNIC is in the generated decoder for a SET type The decoder must take into account the possibility of out of order elements This is handled by using a loop to parse each element in the message Each time an item is parsed an internal mask 60 SEQUENCE OF bit within the decoder is set to indicate the element was received The complete set of received elements is then checked after the loop is completed to verify all required elements were received SEQUENCE OF The ASN 1 SEQUENCE OF type is converted into one of the following C C types e A doubly linked list structure OSRTDList for C or ASN1TSeqOfList a class derived from OSRTDList for C e A structure containing an integer count of
238. ied to all generated typedef names and function names for the production The calling sequence for each generated initialization function is as follows asnlInit_ lt name gt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pvalue argument is used to pass a pointer to a variable of the item to be initialized Generated Memory Free Functions The genFree option causes functions to be generated that free dynamic memory allocated using the ASNIC run time memory management functions and macros rtxMem By default all memory held within a context is freed using the rtxMemFree run time function It is also possible to free an individual memory item using the rtMemFreePtr function But it is not possible to free all 239 Generated Print Functions memory held within a specific generated type container For example a SEQUENCE type could contain elements that require dynamic memory These elements in turn can reference other types that require dynamic memory The generated memory free functions make it possible to release all memory held within a variable of the type with a single call Generated memory free functions are written to the main lt module gt c file This file contains com mon constants global variables and functions that are generic to all type of encode decode func tions If the cfile command line option is used the functions are written to the specified c o
239. ield gt lt ObjectSet gt element1 81 Unions Table Constraint Model In this definition lt class gt would be replaced with a reference to an Information Object Class lt fixed type field gt would be a fixed type field wtihin that class and lt type fiela gt would be a type field within the class lt objectset gt would be a reference to an Information Object Set which would define all of the possibilities for content within the message The first element lt element1 gt would be used as the index element in the object set relation An example of this pattern from the S1AP LTE specification is as follows InitiatingMessage SEQUENCE procedureCode S1AP ELEMENTARY PROCEDURE amp procedureCode S1AP ELEMENTARY PROCEDURES criticality S1AP ELEMENTARY PROCEDURE amp criticality SLAP ELEMENTARY PROCEDURES procedureCode value S1AP ELEMENTARY PROCEDURE amp InitiatingMessage SLAP ELEMENTARY PROCEDURES procedureCode In this definition procedureCode and criticality are defined to be a enumerated fixed types and value is defined to be an open type field to hold variable content as defined in the object set definition In the legacy model defined below a loose coupling would be defined for the open type field using the built in asNiobject s
240. ignature in addition to the name argument the method also takes a buffer and bufSize argument to describe the buffer to which the text is to be written The second signature does not take a name argument instead the name of the item that the control class instance describes is defaulted Print to Stream The genPrtToStrm option causes functions to be generated that print the contents of variables of generated types to an output stream via a user defined callback function The advantage of these functions is that a user can register a callback function and then the print stream is automatically directed to the callback function This makes it easier to support print to file or print to window type of functionalities It also make it possible to create an optimized print to string capability by maintaining a structure that keeps track of the current end of string position in the output buffer The generated print to string functions always must use the strlen run time function to find the end position an operation that becomes compute intensive in large string buffers that are constantly appended to It is possible to specify the name of a c or cpp file as an argument to this option to specify the name of the file to which these functions will be written This is an optional argument If not specified the functions are written to separate files for each module in the source file The format of the name of each file is lt module gt PrtToStrm c If
241. ill automatically allocate memory to hold a parsed string based on the received length of the string In the static case the length of the character array is determined by adjusting the given size value which represents the number of bits into the number of bytes required to hold the bits Dynamic Bit String ASN 1 production lt name gt BIT STRING Generated C code typedef ASN1IDynBitStr lt name gt Generated C code typedef ASN1ITDynBitStr ASN1IT_ lt name gt In this case different base types are used for C and C The difference between the two is the C version includes constructors that initialize the value and methods for setting the value The ASN DynBitStr type 1 e the type used in the C mapping is defined in the asn type h header file as follows typedef struct ASN1DynBitStr OSUINT32 numbits const OSOCTET data ASN1IDynBitStr The ASN1TDynBitStr type is defined in the asn CppTypes h header file as follows struct ASNITDynBitStr public ASN1DynBitStr ctors ASN1TDynBitStr numbits 0 ASNITDynBitStr OSUINT32 _numbits OSOCTET _data ASN1TDynBitStr ASN1DynBitStr amp _bs ASNITDynBitStr Note that memory management of the byte array containing the bit string data is the responsibility of the user The wrapper class does not free the memory on destruction nor deep copy the data when a string is copied Static sized BIT STRING ASN 1 production lt
242. ill be inserted to capture encoded extension elements for inclusion in the final encoded message This element will be of type OSRTDList and have the name extElem1 This is a linked list of open type fields Each entry in the list is of type ASNI OpenType The fields will contain complete encodings of any extension elements that may have been present in a message when it is decoded On subsequent encode of the type the extension fields will be copied into the new message The noOpenExt command line option can be used to alter this default behavior If this option is specified the extElem element is not included in the generated code and extension data that may be present in a decoded message is simply dropped If the SEQUENCE type contains an extension marker and extension elements then the actual extension elements will be present in addition to the extElem1 element These elements will be treated as optional elements whether they were declared that way or not The reason is because a version message could be received that does not contain the elements Additional bits will be generated in the bit mask if version brackets are present These are groupings of extended elements that typically correspond to a particular version of a protocol An example would be as follows TestSequenc SEQUENCE item code INTEGER 0 254 item name TA5String SIZE 3 10 OPTIONAL woh Ty
243. ins no size constraint then a dynamic array is used The list keyword can also be used in a similar fashion to specify the use of a linked linked structure to hold the elements lt storage gt list lt storage gt See the section entitled Compiler Configuration File for further details on setting up a configuration file Dynamic SEQUENCE OF Type ASN 1 production 61 SEQUENCE OF lt name gt SEQUENCE OF lt type gt Generated C code typedef struct OSUINT32 n lt type gt elem lt name gt Generated C code typedef struct public ASNITPDU OSUINT32 n lt type gt elem ASN1T_ lt name gt ASN1T_ lt name gt ASN1IT_ lt name gt Note that parsed values can be accessed from the dynamic data variable just as they would be from a Static array variable i e an array subscript can be used ex elem 0 elem 1 In the case of C a constructor is generated to initialize the element count to zero If the type represents a PDU type either by default by not referencing any other types or explicitly via the pdu command line option the ASN TPDU base class is extended and a destructor is added This destructor ensures that memory allocated for elements is freed upon destruction of the object Static sized SEQUENCE OF Type ASN 1 production lt name gt SEQUENCE SIZE lt len gt OF lt type gt Generated C code typedef str
244. inter to a variable of this type declared somewhere in his or her program The variable should be initialized using the rtInitCon text run time library function see the C C Common Run Time Library Reference Manual for a complete description of this function 149 Generated C Function For mat and Calling Parameters The pvalue argument holds a pointer to the data to be encoded and is of the type generated from the ASN 1 production The tagging argument is for internal use when calls to encode functions are nested to accomplish encoding of complex variables It indicates whether the tag associated with the production should be applied or not implicit versus explicit tagging At the top level the tag should always be applied so this parameter should always be set to the constant ASNIEXPL for EXPLICIT The function result variable 1en returns the length of the data actually encoded or an error status code if encoding fails Error status codes are negative to tell them apart from length values Return status values are defined in the asnitype h include file Procedure for Calling C Encode Functions This section describes the step by step procedure for calling a C BER or DER encode function This method must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done Note that the procedures described here cannot be used if stream based en
245. ion is as follows stat asnlBSE_ lt name gt OSCTXT pctxt lt name gt pvalue ASNiTagType tagging In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program This variable must be initialized using both the rtInitContext and rtStreamBuflnit run time library functions see the C C Common Run Time Library Reference Manual for a description of these functions The pvalue argument holds a pointer to the data to be encoded and is of the type generated from the ASN 1 production The tagging argument is for internal use when calls to encode functions are nested to accomplish encoding of complex variables It indicates whether the tag associated with the production should be applied or not implicit versus explicit tagging At the top level the tag should always be applied so this parameter should always be set to the constant ASNIEXPL for EXPLICIT The function result variable stat returns the completion status of the operation 0 0 means the SUCCESS Procedure for Calling Streaming C Encode Functions This section describes the step by step procedure for calling a strea
246. ions 0 ce eceeceeseesseceseceeeeesseecnaeceeenseeenaeees 195 Procedure for Using the C Control Class Decode Method cee eeeeeeeeeeereee 197 Decoding a Series of Messages Using the C Control Class Interface 199 Performance Considerations Dynamic Memory Management eseceeseeeeeeees 200 Generated Octet Encoding Rules OER Functions 0 eee eeeeescecsneceseeeeeeeeaeecaecnseeeseeeeaeees 201 Generated OER Encode Functions 2 2 12icdiceeclaindinnciGnnGa lancet 201 Generated C Function Format and Calling Parameters ceescceeeseeeeeseeeeeteeees 201 Populating Generated Structure Variables for Encoding eee eeeeeeseeeseeeeeeeees 202 Procedure for Calling C Encode Functions oo cee ceeeeseessecsseeseeeeeseecsaeenseesseeennees 202 Generated OER Decode Functions 2 i2 2 53scci tn enteceneeis eee aed 204 ASNIC Generated C Function Format and Calling Parameters ceeeceeeeceeeeseeeeeteeees 204 Procedure for Calling C Decode Functions 00 0 eee eeeceeeseeeneeceseceeeeeseeeeseeeaeenes 204 Generated Medical Device Encoding Rules MDER Functions 00 ceeceeeeeeeeeceeeeeeeeeeteeeees 207 Generated IMDER Encode Functions jcii2 isiessddnieldaniies divtiees docetuediard cea neeteieass 207 Generated C Function Format and Calling Parameters eescceeesceeeeteeeenteeees 207 Procedure for Calling C Encode Functions 20 0 0 cee eeceessecsseceseeeseeeeseecnaeesseeeseeeenees 208 En
247. ions such as enumeration items with the same name REAL Value The REAL type causes a define statement to be generated in the header file of the form ASN1V_ lt valueName gt Where lt valueName gt would be replaced with the name in the ASN 1 source file By generating define statements the symbolic names can be included in the source code making it easier to adjust the boundary values This mapping is defined as follows ASN 1 production lt name gt REAL lt value gt Generated code define ASN1V_ lt name gt lt value gt For example the following declaration 76 Enumerated Value Specification rvalue REAL 5 5 will cause the following statement to be added to the generated header file define ASN1V_rvalue 5 5 The reason the asniv_ prefix is added is to prevent collisions with other declarations such as enu meration items with the same name Enumerated Value Specification The mapping of an ASN 1 enumerated value declaration to a global C or C value declaration is as follows ASN 1 production lt name gt lt EnumType gt lt value gt Generated code OSUINT32 lt name gt lt value gt Binary and Hexadecimal String Value Binary and hexadecimal string value specifications cause two global C variables to be generated a numocts variable describing the length of the string and a data variable describing the string contents The mapping for a binary string is as follows note
248. is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each encode function follows stat mderEnc_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable should be initialized using the 207 Procedure for Calling C Encode Functions mderInitContext run time library function see the C MDER Runtime Library Reference Manual for a complete description of this function The pvalue argument holds a pointer to the data to be encoded and is of the type generated from the ASN 1 production The function result variable st at returns an error status code if encoding fails Return status values are defined in the asnitype h include file Procedure for Calling C Encode Functions This section describes the step by step procedure for calling a C MDER encode function
249. is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each decode function is as follows status mderDec_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable must be initialized using the mderInitContext run time function before use The pvalue argument is a pointer to a variable of the generated type that will receive the decoded data The function result variable status returns the status of the decode operation The return status will be greater than or equal to zero if decoding is successful or negative if an error occurs Return status values are defined in the asn type h include file Procedure for Calling C Decode Functions This section describes the step by step procedure for calling a C MDER decode function This meth
250. is ex pired 41 RTERR_UNEXPELEM Unexpected element encountered This status code is returned when an element is encountered in a position where something else for example an attribute was expected 42 RTERR_INVOCCUR Invalid number of occurrences This status code is returned by the decoder when an XML in stance contains a number of occurrences of a repeating element that is outside the bounds minOccursmaxOccurs defined for the element in the XML schema 43 RTERR_INVMSGBUF Invalid message buffer has been passed to de code or validate method This status code is re turned by decode or validate method when the used message buffer instance has type different from OSMessageBufferIF XMLDecode 44 RTERR_DECELEMFAIL Element decode failed This status code and pa rameters are added to the failure status by the decoder to allow the specific element on which a decode error was detected to be identified 45 RTERR_DECATTRFAIL Attribute decode failed This status code and pa rameters are added to the failure status by the 275 General Status Messages Error Code Error Name Description decoder to allow the specific attribute on which a decode error was detected to be identified 46 RTERR_STRMINUSE Stream in use This status code is returned by stream functions when an attempt is made to ini tialize a stream or create a reader or writer when
251. is method will be generated only if it is required to check a table constraint OPTIONAL keyword Fields within a CLASS can be declared to be optional using the OPTIONAL keyword This indi cates that the field is not required in the information object An additional construct is added to the generated code to indicate whether an optional field is present in the information object or not This construct is a bit structure placed at the beginning of the generated structure This structure always has variable name m and contains single bit elements of the form lt fieldname gt Present as follows struct unsigned lt field namel gt Present 1 unsigned lt field name2 gt Present 1 m 91 Legacy Table Constraint Model In this case the fields included in this construct correspond to only those fields marked as OP TIONAL within the CLASS Ifa CLASS contains no optional fields the entire construct is omitted For example we will change the CLASS in the previous example to make one field optional ATTRIBUTE CLASS amp Type OPTIONAL amp id OBJECT IDENTIFIER UNIQUE In this case the following C typedef is generated in C struct or C class definition struct unsigned TypePresent 1 m When this structure is populated for encoding the information object processing code will set TypePresent flag accordingly to indicate whether the field is present or not In C code generati
252. is the direct compilation of XML schema files It is also important to note that the xsd switch is complementary to the xml switch when gener ating XML encoders and decoders This is because the XML schema produced from the ASN 1 specification using the xsd switch can be used to validate the XML messages generated using the XML encode functions Similarly an XML instance can be validated using the generated XML schema prior to decoding XML C encode functions are generated when the xml switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C XML encode function is generated In the case of XML schema a C encode function is generated for each type and global element declaration This function will convert a populated C variable of the given type into an XML en coded message i e an XML document 228 Generated C Function For mat and Calling Parameters If C code generation is specified a control class is generated that contains an Encode method that wraps this function This function is invoked through the class interface to encode an ASN 1 message into the variable referenced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each generated XML encode function is as follows lt namespace gt XmlEnc_ lt prefix gt lt prodName gt where lt namespace gt is an optional C namespace prefix lt prodName
253. jects made with previous versions may be loaded with version 6 3 but new projects are incompatible with previous versions Additional metadata are stored in the project file to help with version tracking Files may be added to a project in the following window 22 Common Code Generation Options Select Files and Directories ASN 1 XSD Files C acv630 cpp sample_ber employee employee asn Include Import Directories Configuration File s Output Directory C acv630 cpp sample_ber employee In this window the ASN 1 file or files to be compiled are selected This is done by clicking the Add button on the right hand side of the top windows pane A file selection box will appear allowing you to select the ASN 1 or XSD files to be compiled Files can be removed from the pane by highlighting the entry and clicking the Remove button ASN 1 specifications and XML Schema Documents must not be compiled in the same project Once an asn file has been added no xsd files may be added Include directories are selected in a similar manner in the middle pane These are directories the compiler will search for import files By default the compiler looks for files in the current working directory with the name of the module being imported and extension asn or xsd Additional directories can be searched for these files by adding them here User defined configuration files are specified in the third pane These allow
254. l by including them within an lt element gt section 40 Compiler Error Reporting Name Values Description lt name gt lt name gt lt ctype gt element name chararray This attribute identifies the element within a SE QUENCE SET or CHOICE construct to which this section applies It is required This is used to specify a specific C type be used in place of the default definition generated by ASNIC In the case of elements the only sup ported customization is for character string types which would normally be represented by a char acter pointer type char to be changed to use static character arrays This can only be done if the string type contains a size constraint lt isOpenType gt n a This flag variable specifies that this element will be decoded as an open type 1 e skipped Refer to the section on deferred decoding for further information Note that this variable can only be used with BER CER or DER encoding rules lt notUsed gt n a This flag variable specifies that this element will not be used at all in the generated code It can only be applied to optional elements within a SEQUENCE or SET or to elements within a CHOICE Its purpose is for production of more compact code by allowing users to configure out items that are of no interest to them lt perEncoding gt perEncoding gt lt storage gt lt storage gt lt hex data dynam
255. lace the high level memory allocation functions with functions that implement a custom memory management scheme This is done by implementing some or all of the C rtxMemHeap functions defined in the following interface note a default implementation is shown that replaces the ASN1C memory manager with direct calls to the standard C run time memory management functions include lt stdlib h gt include rtxMemory h Create a memory heap int rtxMemHeapCreate void ppvMemHeap return 0 Allocate memory void rtxMemHeapAlloc void ppvMemHeap int nbytes return malloc nbytes Allocate and zero memory void rtxMemHeapAllocZ void ppvMemHeap int nbytes void ptr malloc nbytes if 0 ptr memset ptr 0 nbytes return ptr Free memory pointer void rtxMemHeapFreePtr void ppvMemHeap void mem_p free mem_p Reallocate memory void rtxMemHeapRealloc void ppvMemHeap void mem_p int nbytes_ return realloc mem_p nbytes_ 141 Dynamic Memory Management Clears heap memory frees all memory reset all heap s variables void rtxMemHeapFreeAll void ppvMemHeap should remove all allocated memory there is no analog in standard memory management Frees all memory and heap structure as well if was allocated void rtxMemHeapRelease void ppvMemHeap should free all memory allocated fr memory heap
256. later section in this document It is used to include a special event that is fired when a PER message is being parsed This event occurs at the location a value should be present in the message but is not and a default value has been specified in the ASN 1 file for the element In this case the normal event sequence startElement contents endElement is executed using the default value This configuration item is used to specify the root directory of the ASNIC installation for makefile or Visual Studio project generation It is only needed if generation of these items is done outside of the ASNIC installation lt storage gt lt storage gt dynamic static list ar ray or dynamicArray keyword If dynamic it indicates that dynamic storage 1 e pointers should be used everywhere with in the generated types where use could result in lower memory consumption These places in clude the array element for sized SEQUENCE OF SET OF types and all alternative elements within CHOICE constructs If static it indicates static types should be used in these places In general static types are easier to work with If list a linked list type will be used for SE QUENCE OF SET OF constructs instead of an array type If array an array type will be used for SEQUENCE OF SET OF constructs The max Size attribute can be used in this case to spec ify the size of the array variable for example lt storage maxSize 12 gt arra
257. le decode function call When combined with the fast copy procedure defined above this can significantly reduce decoding time because large parts of messages can be skipped Deferred decoding can be done on elements defined within a SEQUENCE SET or CHOICE con struct It is done by designating an element to be an open type by using the lt isOpenType gt con figuration setting This setting causes the ASN1C compiler to insert an Asn OpenType placeholder in place of the type that would have normally been used for the element The data in its original encoded form will be stored in the open type container when the message is decoded If fast copy is used only a pointer to the data in the message buffer is stored so large copies of data are avoided The data within the deferred decoding open type container can be fully decoded later by using a special decode function generated by the ASNIC compiler for this purpose The format of this function is as follows asnlD_ lt ProdName gt _ lt ElementName gt _OpenType OSCTXT pctxt lt ElementType gt pvalue 176 Generated BER Streaming Decode Functions Here lt ProdName gt is replaced with name of the type assignment and lt ElementName gt is replaced with name of the element In this function the argument pctxt is used to pass the a pointer to a context variable initialized with the open type data and the pvalue argument will hold the final decoded data value In following ex
258. le with the GNU make utility which is suitable for compiling code on Linux and many UNIX operating systems and 2 A Microsoft Visual Studio compatible makefile This makefile is compatible with the Microsoft Visual Studio nmake utility A GNU compatible makefile is produced by default the Microsoft compatible file is produced when the w32 command line option is specified in addition to genmake Both of these makefile types rely on definitions in the platform mk make include file This file contains parameters specific to different compiler and linker utilities available on different plat forms Typically all the needs to be done to port to a different platform is to adjust the parameters in this file When a makefile is generated it is assumed that the ASN1C project exists within the ASN1C in stallation directory tree The generation logic tries to determine the root directory of the installation 120 Generated VC Project Files by traversing upward from the project directory in an attempt to locate the rtsrc subdirectory which is assumed to be the installation root directory The makefile variable OSROOTDIR is then set to this value A similar traversal is done to locate the platform mk and xmlparser mk files These paths are then set in the makefile If the project directory is located outside of the ASNIC directory tree the user must set the OSROOTDIR environment variable to point at the ASNIC root directory in order for the
259. lement the Octet Encod ing Rules OER as specified in the NTCIP 1102 2004 standard param lt name gt lt value gt This option is used to instantiate all parameter ized types with the ASN 1 modules that are be ing compiled with the given parameter value In this declaration lt name gt refers to the dummy reference in a parameterized type definition and lt value gt refers to an actual value pdu lt typeName gt Designate given type name to be a Protocol Definition Unit PDU type This will cause a C control class to be generated for the given type By default PDU types are determined to be 16 Running ASNIC from the Command line Option Argument Description types that are not referenced by any other types within a module This option allows that behav ior to be overridden The all keyword may be specified for lt type Name gt to indicate that all productions within an ASN 1 module should be treated as PDU types per None This option instructs the compiler to generate functions that implement the Packed Encoding Rules PER as specified in the ASN 1 stan dards prtfmt bracetext details Sets the print format for generated print func tions The details option causes a line by line display of all generated fields in a generated structure to be printed The bracetext option causes a more concise printout showing only the relevant fields in a
260. list is converted to ASN 1 it is modeled as a SEQUENCE OF type For example lt xsd simpleType name MyType gt lt xsd list itemType xsd int gt lt xsd simpleType gt results in the generation of the following C type typedef struct EXTERN MyType 102 xsd any OSUINT32 n OSINT32 elem MyType Special code is added to the generated XML encode and decode function to ensure the data is encoded in spaceseparated list form instead of as XML elements xsd any The xsd any element is a wildcard placeholder that allows an occurence of any element definition to occur at a given location It is similar to the ASN 1 open type and can be modeled as such however ASNIC uses a special type for these items osxspany that allows for either binary or xml textual data to be stored This allows items to be stored in binary form if binary encoding rules are being used and XML text form if XML text encoding is used The definition of the osxspAny type is as follows typedef enum OSXSDAny_binary OSXSDAny_xmlText OSXSDAnyAl1t typedef struct OSXSDAny OSXSDAnyAlt t union OSOpenType binary const OSUTF8CHAR xmlText u OSXSDAny The t value is set to either osxsDAny_binary Or OSXSDAny_xmlText to identify the content type If binary decoding is being done BER DER CER or PER the decoder will populate the binary alternative element if XML decoding is being done the xmitext field is populate
261. lization Functions scicss ssacisassdectscvevsacscrgececssaseacnaesdaasassssed tegoaataassbaceve 176 BER DER Deferred Decoding sgecisoe ues inendien paadisdaenasasenecede spheandedabancearateaoanteses 176 Generated BER Streaming Decode Functions eee eeeeeeeseeenceceseceeeeeeeesaeecsaeenseesees 177 Generated Streaming C Function Format and Calling Parameters 00 0 178 Generated Streaming C Decode Method Format and Calling Parameters 182 Generated PER PUnCUHONS uca ss cline ela in esaa eSEE eam SA E 187 Generated PER Encode Functions s 2 2i0c s2234 denn ested iia adisteea ecieaiesieden dei aan 187 Generated C Function Format and Calling Parameters eesccesesceeeeeeeeeeeeeeees 187 Generated C Encode Method Format and Calling Parameters eeeceeeeeeeees 188 Populating Generated Structure Variables for Encoding cee eeseeeseceeeeeeeeeeneees 188 Procedure for Calling C Encode Functions 0 0 0 cee eeseessecssecsseceseeeeseecsaecnseeeseeeenees 188 Procedure for Using the C Control Class Encode Method 0 0 cee ceeeeeseeeeeees 190 Encoding a Series of PER Messages using the C Interface 00 0 eeeeeeeeeeeeeteeee 194 Generated PER Decode Functions scucin2 niin tek ineeeiheiinn dates 194 Generated C Function Format and Calling Parameters ceesceeesceeeeeeeeeneeeeees 194 Generated C Decode Method Format and Calling Parameters 0 eee 195 Procedure for Calling C Decode Funct
262. lloc and free functions must have the same prototype as the standard C functions Some systems do not have a realloc like function In this case realloc_func may be set to NULL This will cause the malloc_func free_func pair to be used to do reallocations This function must be called before the context initialization function rtInitContext because con text initialization requires low level memory management facilities be in place in order to do its work Note that this function makes use of static global memory to hold the function definitions This type of memory is not available in all run time environments most notably Symbian In this case an alternative function is provided for setting the memory functions This function is rtxJnitContextExt which must be called in place of the standard context initialization function rt nitContext In this case there is a bit more work required to initialize a context because the ASN 1 subcontext must be manually initialized This is an example of the code required to do this int stat rtxInitContextExt pctxt malloc_func realloc_func free_func if 0 stat Add ASN 1 error codes to global table rtErrASNlInit Init ASN 1 info block stat rtCtxtInitASNlInfo pctxt Memory management can also be tuned by setting the default memory heap block size The way memory management works is that a large block of memory is allocated up front on the first mem ory manage
263. lt element2 name gt 2 typedef struct int t union lt typel gt lt element1l name gt lt type2 gt lt element2 name gt u lt name gt OF typedef struct lt tempNamel gt typedef struct lt tempName2 gt typedef struct int t union lt tempNamel gt lt elementl name gt lt tempName2 gt lt element2 name gt u 66 CHOICE lt name gt If the static command line option or lt storage gt static lt storage gt configuration variable is set for the given production then pointers will not be used for the variable declarations Note This is true for the C case only for C pointers must be used due to the fact that the generated code will not compile if constructors are used in a non pointer variable within a union construct The C mapping is the same with the exception that the asnwit_ prefix is added to the generated type name lt typel gt and lt type2 gt are the equivalent C types representing the ASN 1 types lt element1 type gt and lt element 2 type gt respectively lt tempName1 gt and lt t empName2 gt represent the names of temporary types that may have been generated as the result of using nested constructed types within the def inition Choice alternatives may be unnamed in which case lt element name gt is derived from lt ele ment type gt by making the first letter lowercase One needs to be careful when nesting CHOICE
264. lternative to using the control class interface if C code generation was done These are the steps involved calling a compiler generated decode function 1 Prepare a context variable for decoding 2 Open an input stream for the XML document to be decoded 3 Decode the initial tag value to figure out what type of message was received optional 4 Call the appropriate compiler generated decode function to decode the message 5 Free the context after use of the decoded data is complete to free allocated memory structures Before a C XML decode function can be called the user must first initialize a context block struc ture The context block structure is initialized by calling the rtXmlInitContext function An input stream is then opened using one of the rtxStream functions If the data is to be read from a file the rtxStreamFileCreateReader function can use used Similar functions exist for opening a memory or socket based stream 234 Procedure for Calling C Decode Functions If the user knows the type of XML message that is to be processed he can directly call the decode function at this point If not the user may call the rtXmlpMatchStartTag method to match the initial tag in the message with a known start tag The user can continue to do this until a match is found with one of the expected message types Note that the rtXmlpMarkLastEvent function must be called if the tag is to be reparsed to attempt another match operation
265. makefile generation to be successful If this is done it is assumed that the platform mk and xmlparser mk files are located in this directory as well If the compiler is unable to determine the root directory using any of the methods described above an error will be generated and the user will need to manually edit the makefile to set the required root directory parameters and makefile include file paths Generated VC Project Files The vcproj option causes Microsoft Visual Studio project and workspace files to be generated that can be used to build the generated code The files are compatible with Visual Studio version 6 0 but higher versions of Visula Studio can convert these files to the newer formats This option can be used with the d option that will generate project files to compile all generated code into a DLL and mt that will add multi threaded compilation options to generated projects Because there are several different versions of Visual Studio the vcproj option takes an optional argument the release year of the version of Visual Studio used This modifies the resulting project to link against the appropriate set of libraries distributed with ASNIC If no year is specified the project will link against the usual c and cpp directories If 2003 is specified the project will us the c_vs2003 and cpp_vs2003 directories If 2005 is specified c_vs2005 and cpp_vs2005 will be used Likewise if 2008 is specified c_vs2008 and cpp_vs200
266. ment call This block is then subdivided on subsequent calls until the memory is used up A new block is then started The default value is 4K 4096 bytes The value can be set lower for space constrained systems and higher to improve performance in systems that have sufficient memory resources To set the block size the following run time function should be used void rtxMemSetDefB1kSize OSUINT32 b1lkSize This function must be called prior to context initialization C Memory Management In the case of C the ownership of memory is handled by the control class and message buffer objects These classes share a context structure and use reference counting to manage the allocation 143 Dynamic Memory Management and release of the context block When a message buffer object is created a context block structure is created as well When this object is then passed into a control class constructor its reference count is incremented Then when either the control class object or message buffer object are deleted or go out of scope the count is decremented When the count goes to zero i e when both the message buffer object and control class object go away the context structure is released What this means to the user is that a control class or message buffer object must be kept in scope when using a data structure associated with that class A common mistake is to try and pass a data variable out of a method and use it after the control
267. mented within the error handler 252 How to Use It How to Use It To define event handlers two things must be done 1 One or more new classes must be derived from the Asn NamedEventHandler and or the Asn1ErrorHandler base classes All pure virtual methods must be implemented 2 Objects of these classes must be created and registered prior to calling the generated decode method or function The best way to illustrate this procedure is through examples We will first show a simple event handler application to provide a customized formatted printout of the fields in a PER message Then we will show a simple error handler that will ignore unrecognized fields in a BER message Example 1 A Formatted Print Handler The ASNIC evaluation and distribution kits include a sample program for doing a formatted print of parsed data This code can be found in the cpp sample_per eventHandler directory Parts of the code will be reproduced here for reference but refer to this directory to see the full implementation The format for the printout will be simple Each element name will be printed followed by an equal sign and an open brace and newline The value will then be printed followed by another newline Finally a closing brace followed by another newline will terminate the printing of the element An indentation count will be maintained to allow for a properly indented printout A header file must first be created to hold our
268. mic memory for variable length fields within the structure This memory is tracked within the context structure and is released when the context structure is freed The function result variable stat returns the status of the decode operation Status code 0 0 indi cates the function was successful A negative value indicates decoding failed Return status values are defined in the asn ErrCodes h and rtxErrCodes h header files The reason text and a stack trace can be displayed using the rtxErrPrint function described later in this document Procedure for Calling C Decode Functions This section describes the step by step procedure for calling a C OER decode function 204 Procedure for Calling C Decode Functions Unlike BER the user must know the ASN 1 type of an OER message before it can be decoded This is because the type cannot be determined at run time There are no embedded tag values to reference to determine the type of message received The following are the basic steps in calling a compiler generated decode function 1 Prepare a context variable for decoding 2 Initialize the data structure to receive the decoded data 3 Call the appropriate compiler generated decode function to decode the message 4 Free the context after use of the decoded data is complete to free allocated memory structures Before an OER decode function can be called the user must first initialize a context block structure The context block i
269. ming C BER encode function This method must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done 158 Generated Streaming C Function Format and Calling Parameters Before any encode function can be called the user must first initialize an encoding context This is a variable of type OSCTXT This variable holds all of the working data used during the encoding of a message The context variable is within the top level calling function It must be initialized before use This can be accomplished by using the berStrmInitContext function OSCTXT Cext if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 The next step is to create a stream object within the context This object is an abstraction of the output device to which the data is to be encoded and is initialized by calling one of the following functions e rtxStreamFileOpen e rtxStreamFileAttach e rtxStreamSocketAttach e rtxStreamMemoryCreate e rtxStreamMemoryAttach The flags parameter of these functions should be set to the O9RTSTRMF_OUTPUT constant value to indicate an output stream is being created see the C C Common Run Time Library Reference Manual for a full description of these functions It is also possible to use a simplified f
270. mp commands work despite the fact that the output has been written to a stream This is because a capture buffer is used when tracing is enabled to record all of the encoded information If memory is tight a user should ensure that trace output is turned off when using the stream Encoding a Series of PER Messages using the C Interface When encoding a series of PER messages using the C interface performance can be improved by reusing the message processing objects to encode each message rather than creating and destroying the objects each time A detailed example of how to do this was given in the section on BER message encoding The PER case would be similar with the PER function calls substituted for the BER calls As was the case for BER the encode message buffer object init method can be used to reinitialize the encode buffer between invocations of the encode functions Generated PER Decode Functions PER encode decode functions are generated when the per switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C PER decode function is generated This function will parse the data contents from a PER encoded ASN 1 message and populate a variable of the corresponding type with the data If C code generation is specified a control class is generated that contains a Decode method that wraps this function This function is invoked through the class interface to encode an ASN 1 message into the
271. mpiled and items those productions depend on from IMPORT files der None This option instructs the compiler to generate functions that implement the Distinguished En coding Rules DER as specified in the X 690 ASN 1 standard dll None When used in conjunction with the genMake command line option the generated makefile uses dynamically linked libraries DLLs in Win dows or so files in UNIX instead of statical ly linked libraries dynamicArray none This option specifies that a dynamic array type is to be used for SEQUENCE OF SET OF con structs genbuild None This option instructs the compiler to generate a build script when producing Java source code The generated build script is either a batch file Windows or a shell script UNIX genCompare compare lt filename gt This option allows the specification of a C or C source c or cpp file to which generat ed compare functions will be written Compare Running ASNIC from the Command line Option Argument Description functions allow two variables of a given ASN 1 type to be compared for equality The lt filename gt argument to this option is op tional If not specified the functions will be writ ten to lt modulename gt Compare c where lt mod ulename gt is the name of the module from the ASN 1 source file genCopy copy lt filename gt This option allows the speci
272. n of aligned or unaligned encoding An encode function can then be called to encode the message If the return status indicates success 0 then the message will have been encoded in the given buffer PER encoding starts from the beginning of the buffer and proceeds from low memory to high memory until the message is com plete This differs from BER where encoding was done from back to front Therefore the buffer 188 Procedure for Calling C Encode Functions start address is where the encoded PER message begins The length of the encoded message can be obtained by calling the pe_GetMsgLen run time function If dynamic encoding was specified i e a buffer start address and length were not given the run time routine pe_GetMsgPtr can be used to obtain the start address of the message This routine will also return the length of the encoded message A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC main OSOCTET msgbuf 1024 int msglen stat OSCTXT ctxt OSBOOL aligned TRUE Employee employee typedef generated by ASNIC Populate employee C structure mployee name givenName SMITH Allocate and initialize a new context pointer stat rtInitContext amp ctxt if stat 0 printf rtInitContext failed check license n rtxErrPrint amp ctxt return stat pu_s
273. n a nutshell is adds the angle brackets lt gt around the element names in the startElement and endElement callbacks The data callbacks simply output a textual representation of the data as they do in the print handler case The only difference in reader cpp from the other examples is that 1 There is no declaration of an employee variable to hold decoded data because no type for this variable was generated and 2 The Parse method is invoked instead of the Decode method This is the generated method def inition for a pureparser If one examines the generated class definitions they will see that no Encode or Decode methods were generated Compiling and running this program will show the encoded PER message written to stdout as an XML message The resulting message is also saved in the message xml file 257 258 IMPORT EXPORT of Types ASNIC allows productions to be shared between different modules through the ASN 1 IM PORT EXPORT mechanism The compiler parses but ignores the EXPORTS declaration within a module As far as it is concerned any type defined within a module is available for import by another module When ASNIC sees an IMPORT statement it first checks its list of loaded modules to see if the module has already been loaded into memory If not it will attempt to find and parse another source file containing the module The logic for locating the source file is as follows 1 The configuration file if s
274. n encoded to the given stream Streaming BER encoding starts from the beginning of the message until the message is complete This is sometimes referred to as forward encoding This differs from regular BER where encod ing is done from back to front Indefinite lengths are used for all constructed elements in the mes sage Also there is no permanent buffer for streaming encoding all octets are written to the stream The buffer in the context structure is used only as a cache 157 Generated Streaming C Function Format and Calling Parameters If C code generation is specified a control class is generated that contains an EncodeTo method that wraps the stream encode C function This function is invoked through the class interface to convert a populated msgData attribute variable into an encoded ASN 1 message Generated Streaming C Function Format and Calling Parameters The format of the name of each generated streaming encode function is as follows asnlBSE_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each encode funct
275. n his or her program The value argument contains the value to be encoded or holds a pointer to the value to be encoded This variable is of the type generated from the ASN 1 production The object is passed by value if it is a primitive ASN 1 data type such as BOOLEAN INTEGER ENUMERATED etc It is passed using a pointer reference if it is a structured ASN 1 type value Check the generated function prototype in the header file to determine how the value argument is to be passed for a given function The function result variable stat returns the status of the encode operation Status code 0 0 in dicates the function was successful Note that this return value differs from that of BER encode functions in that the encoded length of the message component is not returned only an OK status 187 Generated C Encode Method Format and Calling Parameters indicating encoding was successful A negative value indicates encoding failed Return status val ues are defined in the asnItype h include file The error text and a stack trace can be displayed using the rtErrPrint function Generated C Encode Method Format and Calling Parameters Generated encode functions are invoked through the class interface by calling the base class Encode method The calling sequence for this method is as follows stat lt object gt Encode In this definition lt object gt is an object of the class generated for the given production The fun
276. n this definition lt object gt is an instance of the control class 1 e ASN1C_ lt prodName gt generated for the given production An ASNIBERDecodeBuffer object reference is a required argument to the lt object gt constructor This is where the message start address and length are specified The message length argument is used to specify the size of the message if it is known In ASN 1 BER or DER encoded messages the overall length of the message is embedded in the first few 169 Generated C Decode Method Format and Calling Parameters bytes of the message so this variable is not required It is used as a test mechanism to determine if a corrupt or partial message was received If the parsed message length is greater than this value an error is returned If the value is specified to be zero the default then this test is bypassed The function result variable status returns the status of the decode operation The return status will be zero if decoding is successful or a negative value if an error occurs Return status values are defined in Appendix A of the C C Common Functions Reference Manual and online in the asnItype h include file Procedure for Using the C Control Class Decode Method Normally when a message is received and read into a buffer it can be one of several different message types So the first job a programmer has before calling a decode function is determining which function to call The ASNIBERDecod
277. n to ASN 1 and compiling the resulting specification with ASN1C it is much simpler The generated encoder and decoder make the necessary adjustments to ensure that the encodings are the same regardless of the process used Repeating Elements It is common in XSD to specify that elements within a composite group can occur a multiple number of times For example lt xsd complexType name Name gt lt xsd sequence gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string gt lt xsd element name familyName type xsd string maxOccurs 2 gt lt xsd sequence gt lt xsd complexType gt In this case the familyName element may occur one or two times If minoccurs is absent its de fault value is 1 X 694 specifies that a SEQUENCE OF type be formed for this element and then the element renamed to familyName list to reference this element The C code produced by this transformation is as follows typedef struct EXTERN Name const OSUTF8CHAR givenName const OSUTF8CHAR initial struct OSUINT32 n const OSUTF8CHAR elem 2 familyName_list Name In this case an array was used to represent familyName_list In others a linked list might be used to represent the repeating item xsd list Another way to represent repeating items in XSD is by using xsd list This is a simple type in XSD that refers to a space separated list of repeating items When the
278. name givenName SMITH step 3 instantiate an instance of the ASN1C_ lt ProdName gt class to associate th ncode buffer and message data ASN1C_PersonnelRecord employ encodeBuffer msgData steps 4 and 5 encode and check return status if stat employee Encod 0 printf Encoding was successful n printf Hex dump of encoded record n ncodeBuffer hexDump printf Binary dump n encodeBuffer binDump employee step 6 get start of message pointer and message length start of message pointer is start of msgbuf call getMsgLen to get message length 191 Procedure for Using the C Control Class Encode Method msgptr encodeBuffer getMsgPtr will return amp msgbuf len encodeBuffer getMsgLen else printf Encoding failed n encodeBuffer printErroriInfo exit 0 msgptr and len now describe fully encoded messag In general static buffers should be used for encoding messages where possible as they offer a substantial performance benefit over dynamic buffer allocation The problem with static buffers however is that you are required to estimate in advance the approximate size of the messages you will be encoding There is no built in formula to do this the size of an ASN 1 message can vary widely based on data types and other factors If performance is not a significant issue then dynamic
279. name gt BIT STRING SIZE lt len gt Generated C code typedef struct OSUINT32 numbits 46 BIT STRING OSOCTET data lt adjusted_len gt lt name gt Generated C code typedef struct lt name gt OSUINT32 numbits OSOCTET data lt adjusted_len gt ctors ASN1T_ lt name gt ASN1IT_ lt name gt OSUINT32 _numbits const OSOCTET _data ASN1IT_ lt name gt lt adjusted_len gt lt len gt DI Fiz For example the following ASN 1 production BS PRIVATE 220 BIT STRING SIZE 42 Would translate to the following C typedef typedef struct BS OSUINT32 numbits OSOCTET data 6 BS In this case six octets would be required to hold the 42 bits eight in the first five bytes and two in the last byte In the case of small sized strings less than or equal to 32 bits a built in type is used rather than generating a custom type This built in type is defined as follows typedef struct ASN1BitStr32 OSUINT32 numbits OSOCTET data 4 ASNIBitStr32 The C variant ASN1TBitStr32 adds constructors for initialization and copying Note that for C ASNIC generates special constructors and assignment operators to make pop ulating a structure easier In this case two constructors were generated a default constructor and one that takes numbits and data as arguments Named Bits In the ASN 1 standard it is possible to d
280. name gt pvalue ASNiTagType tagging int length In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of decode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The variable must be initialized using the berStrmInitContext run time function before use The pvalue argument is a pointer to a variable of the generated type that will receive the decoded data The tagging and length arguments are for internal use when calls to decode functions are nested to accomplish decoding of complex variables At the top level these parameters should always be set to the constants ASNIEXPL and zero respectively The function result variable status returns the status of the decode operation The return status will be zero if decoding is successful or negative if an error occurs Return status values are defined in the rtxErrCodes h include file Procedure for Calling Streaming C Decode Functions This section describes the step by step procedure for calling a streaming C BER decode function This procedure must be followed if C code generation was done This procedure can also be used as an alternative to using the control class interface if C code
281. namic memory when done rtFreeContext amp ctxt The only changes were the addition of the for loop and the call to rtxMemReset that was added at the bottom of the loop This function resets the memory tracking parameters within the con text to allow previously allocated memory to be reused for the next decode operation Optionally rtxMemFree can be called to release all memory This will allow the loop to start again with no outstanding memory allocations for the next pass Generated Streaming C Decode Method For mat and Calling Parameters Generated C streaming decode functions are invoked through the C class interface by calling the generated DecodeFrom method The calling sequence for this method is as follows status lt object gt DecodeFrom lt inputStream gt In this definition lt object gt is an instance of the control class i e ASN1C_ lt prodName gt generated for the given production The lt inputStream gt placeholder represents an input stream object type This is an object derived from an ASN DecodeStream class The function result variable stat returns the completion status Error status codes are negative Return status values are defined in the rtxErrCodes h include file 182 Generated Streaming C Decode Method Format and Calling Parameters Another way to decode message using the C class interface is to use the gt gt stream operator lt inputStream gt gt gt
282. nction can be called to encode the message If the return status indicates success positive length value the run time library function xe_getp can be called to obtain the start address of the encoded message Note that the returned address is not the start address of the target buffer BER encoded messages are constructed from back to front i e starting at the end of the buffer and working 150 Generated C Function For mat and Calling Parameters backwards so the start point will fall somewhere in the middle of the buffer after encoding is complete This is illustrated in the following diagram Encode buffer size 1K Buffer start Start of 4 Encode this way End of Buffer address 0x500 Message 0x100 0x200 In this example a 1K encode buffer is declared which happens to start at address 0x100 When the context is initialized with a pointer to this buffer and size equal to 1K it positions the internal encode pointer to the end of the buffer address 0x500 Encoding then proceeds from back to front until encoding of the message is complete In this case the encoded message turned out to be 0x300 768 bytes in length and the start address fell at 0x200 This is the value that would be returned by the xe_getp function A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC int main OSOCTET msgbuf 1024 msgptr in
283. nd below the cfile option did not have any effect for files containing copy print compare etc func tions For ASNIC 5 7 and above cfile causes everything to be output to one file unless specific filename parameters are specified with genPrint genCopy etc Once again to maintain the pre vious behavior the compat 5 6 option can be used Generated C files and the symbian Option ASNIC version 6 1 introduced the symbian option to generate code that targets the Symbian platform While an exhaustive discussion of the differences between Symbian C and standard C is impractical for this User s Guide the differences in generated code are relatively minimal Two principle areas of concern are writable static data WSD and extern linkage Writable Static Data Writable static data are per process data that exist throughout the lifetime of the process The use of WSD complicates memory management in many cases especially in shared libraries A minimum of four kilobytes is allocated for WSD every single time a DLL is loaded even if less space is required If 50 bytes were needed for example 4046 bytes would be wasted every time the DLL was loaded For this reason the use of WSD is highly discouraged 118 Extern Linkage In practice WSD are globally scoped variables declared outside of a function struct or class and static variables declared in functions WSD may be eliminated by modifying primitive types with c
284. nd free the context rtxStreamClose amp ctxt rtFreeContext amp ctxt return 0 Procedure for Using the C Interface SAX handler methods are added to the C control class generated for each ASN 1 production The procedure to invoke the generated decode method is similar to that for the other encoding rules It is as follows Instantiate an ASN 1 XER decode buffer object ASNIXERDecodeBuffer to describe the mes sage to be decoded Constructors exist that allow an XML file or memory buffer to be specified as an input source Instantiate an ASN1T_TypeName object to hold the decoded message data Instantiate an ASN1C_TypeName object to decode the message This class associates the mes sage buffer object with the object that is to receive the decoded data The results of the decode operation will be placed in the variable declared in step 2 Invoke the ASN1C_TypeName object Decode method This method initiates and invokes the XML parser s parse method to parse the document This in turn invokes the generated SAX handler methods Release dynamic memory that was allocated by the decoder All memory associated with the decode context is released when both the ASN1IXERDecodeBuffer and ASN1IC_TypeName objects go out of scope A program fragment that could be used to decode an employee record is as follows int main int argc char argv const char filename employee xml int stat st
285. nd in the rtxErrCodes h include file Procedure for Using the C Control Class De code Method The following are the steps are involved in decoding an XML message using the generated C class 1 Instantiate an XML decode buffer object OSXMLDecodeBuffer to describe the message to be decoded There are several choices of constructors that can be used including one that takes 236 Procedure for Using the C Control Class Decode Method the name of a file which contains the XML message one the allows a memory buffer to be specified and one that allows an existing stream object to be used Instantiate an ASN1T_ lt ProdName gt object to hold the decoded message data Instantiate an ASN1C_ lt ProdName gt object to decode the message This class associates the message buffer object with the object that is to receive the decoded data The results of the decode operation will be placed in the variable declared in step 2 Invoke the ASN1C_ lt ProdName gt object Decode or DecodeFrom method Check the return status The return value is a status value indicating whether decoding was successful or not Zero indicates success If decoding failed the status value will be a negative number The decode buffer method printErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred Release dynamic memory that was allocated by the decoder All memory associated with the decode context is
286. nded to contain two additional elements in uyEx tendedtype The resulting C type definitions for MyType MyExtendedType and the special deriva tions type are as follows typedef struct EXTERN MyType const OSUTF8CHAR elementOne OSINT32 elementTwo MyType typedef struct EXTERN MyExtendedType const OSUTF8CHAR elementOne OSINT32 elementTwo const OSUTF8CHAR elementThree OSINT32 elementFour MyExtendedType define T_MyType_derivations_myType 1 define T_MyType_derivations_myExtendedType 2 107 Substitution Groups typedef struct EXTERN MyType_derivations Ent ey union FRCS TESS MyType myType f Pen i DO MyExtendedType myExtendedType u MyType_derivations The derivations type is a choice between the base type and all derivations of that base type It will be used wherever the base type is referenced This makes it possible to use an instance of the extended type in these places The case of restriction is handled in a similar fashion In this case instead of creating a new type with additional elements a new type is created with all restrictions implemented This type may be identical to the base type definition Substitution Groups A substitution group is similar to a complex content type in that it allows derivations from a com mon base In this case however the base is an XSD element and the substitution group
287. ned by the decoder when an invalid sequence of bytes is detected in a UTF 8 char acter string Array index out of bounds This status code is returned when an attempt is made to add some thing to an array and the given index is outside the defined bounds of the array 20 RTERR_INVPARAM Invalid parameter passed to a function of method This status code is returned by a func tion or method when it does an initial check on the values of parameters passed in If a parame ter is found to not have a value in the expected range this error code is returned 21 RTERR_INVFORMAT Invalid value format This status code is returned when a value is received or passed into a func tion that is not in the expected format For ex ample the time string parsing function expects a 272 General Status Messages Error Code Error Name Description string in the form nn nn nn where n s are num bers If not in this format this error code is re turned 22 RTERR_NOTINIT Context not initialized This status code is re turned when the run time context structure OS CTXT is attempted to be used without having been initialized This can occur if rtxInitContext is not invoked to initialize a context variable be fore use in any other API call It can also occur is there is a license violation for example eval uation license expired 23 RTERR_TOOBIG Value will not fit in targe
288. nerate pure parsing functions In this case no C types or encode or decode functions are generated for the productions within the given ASN 1 source file Instead only a set of parser functions are generated that invoke the event handler callback functions This gives the user total control over what is done with the message data Data that is not needed can be discarded and only the parts of the message needed for a given application need to be saved How it Works Users of XML parsers are probably already quite familiar with the concepts of SAX Significant events are defined that occur during the parsing of a message As a parser works through a message these events are fired as they occur by invoking user defined callback functions These callback functions are also known as event handler functions A diagram illustrating this parsing process is as fol Parser ASN 1 decode function lows The events are defined to be significant actions that occur during the parsing process We will define the following events that will be passed to the user when an ASN 1 message is parsed 1 startElement This event occurs when the parser moves into a new element For example if we have a SEQUENCE a b c construct type names omitted this event will fire when we begin parsing a b and c The name of the element is passed to the event handling callback function 251 How it Works 2 endElement This event occurs wh
289. nitial type xsd string gt lt xsd element name familyName type xsd string gt lt xsd sequence gt lt xsd attribute name occupation type xsd string gt lt xsd complexType gt This results in the following C type definition being generated typedef struct EXTERN Name struct unsigned occupationPresent 1 m const OSUTF8CHAR occupation const OSUTF8CHAR givenName const OSUTF8CHAR initial const OSUTF8CHAR familyName Name The attribute is marked as optional hence the occupationPresent flag in the bit mask since XML attributes are optional by default The attribute declarations also occur before the element declara tions in the generated structure Attributes can also be added to a choice group In this case an ASN 1 SEQUENCE is formed consisting of the attribute elements and an embedded element choice for the choice group An example of this is as follows lt xsd complexType name NamePart gt lt xsd choice gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string gt lt xsd element name familyName type xsd string gt lt xsd choice gt lt xsd attribute name occupation type xsd string gt lt xsd complexType gt This results in the following C type definitions being generated define T_NamePart_choice_givenName 1 define T_NamePart_choice_initial 2 define T_NamePart_choice_familyName 3
290. nition XSD for each of the ASN 1 productions in the ASN 1 source file The definitions are written to the giv en filename or to lt modulename gt xsd if the file name argument is not provided Using the GUI Wizard to Run ASN1C ASNIC includes a graphical user interface GUI wizard that can be used as an alternative to the command line version It is a cross platform GUI and has been ported to Windows and several UNIXes The GUI makes it possible to specify ASN 1 files and configuration files via file naviga tion windows to set command line options by checking boxes and to get online help on specific options The Windows installation program should have installed an ASN1C Compiler option on your computer desktop and an ASN1C option on the start menu The wizard can be launched using either of these items The UNIX version should be installed in aswic_INSTALL_DIR bin no desk top shortcuts are created so it will be necessary to create one or to run the wizard from the com mand line Using Projects The wizard is navigated by means of Next and Back buttons Following is the initial window 20 Using Projects ASN1C Project Wizard E New Project ASN1C 6 3 0 Evaluation License License expire date is Thu Apr 15 11 08 09 2010 o Open Project The status window will display the version of the software you have installed as well as report any errors upon startup that occur such as a missing license fil
291. not This construct is a bit structure placed at the beginning of the generated sequence structure This structure always has variable name m and contains single bit elements of the form lt ele ment name gt Present as follows struct unsigned lt element namel gt Present 1 unsigned lt element name2 gt Present 1 m In this case the elements included in this construct correspond to only those elements marked as OPTIONAL within the production If a production contains no optional elements the entire construct is omitted For example the production in the previous example can be changed to make both elements op tional Aseq PRIVATE 2 SEQUENCE x INTEGER OPTIONAL AntInt OPTIONAL In this case the following C typedef is generated typedef struct Aseq struct unsigned xPresent 1 unsigned anIntPresent 1 m OSINT32 X AnInt anInt Aseq When this structure is populated for encoding the developer must set the xPresent and anIntPresent flags accordingly to indicate whether the elements are to be included in the encoded message or not Conversely when a message is decoded into this structure the developer must test the flags to determine if the element was provided in the message or not The generated C structure will contain a constructor if OPTIONAL elements are present This constructor will set all optional bits to zero when a variable of the
292. not found and the information object set is not extensible then a table constraint er ror status will be returned If the information object set is extensible a normal status is returned Simple Table Constraint 1 This function will verify all the fixed type values match what is defined in the table constraint information object set If an element value does not exist in the table i e the information object set and the object set is not extensible then a table constraint violation exception will be thrown The normal encode logic is then performed to encode all of the standard and open type fields in the message On the decode side the logic is reversed The normal decode logic is performed to populate the standard and open type fields in the generated structure 133 General Procedure for Ta ble Constraint Encoding Relative Table Constraint 1 The lookupObject method is invoked on the decoded key field value to find an object match 2 If a match is found the table constraint decode function as defined above is invoked This func tion will verify all fixed type values match what is defined in the information object definition and will fully decode all type fields and store pointers to the decoded type variables in the ASN1TObject decoded fields 3 Ifa match is not found and the information object set is not extensible then a table constraint er ror status will be returned If the information object set is extensi
293. notations E Generate Non native Attribute Annotations Specify the Target XML Namespace V Reference Types in the asn1 xsd schema These options are described in Running ASNIC from the command line C C Code Generation Options The following windows describe the options available for generating C or C source code 27 C C Code Generation Options C C Code Generation Options z Code Modifications Makefiles and Projects Additional Code Generation V Generate Initialization Functions Generate Memory Free Functions genfree Generate Named Bit Macros genBitMacros Generate table constraints using unions table unions enerated C C Type Modifiers Generate static member variables in choice constructs static Use fully qualified enums fgenum Generate Symbian compatible code Add a header guard prefix Add a C namespace Output File Options Output code to c h files based on module names Max lines per file Output each generated function to a separate source file maxcfiles Output all code to a single c h file c The first tab Code Modifications contains options for adding C C specific function types adding type modifiers and changing how files are output By default ASN1C generates initialization functions that are used by generated code to ensure that newly constructed types have appropriate default values Memory free functions are not generated by de
294. ns_S1AP_ELEMENTARY_PROCEDURES_handoverResourceAllocation 86 Legacy Table Constraint Model T_S1AP_PDU_Descriptions_S1AP_ELEMENTARY_PROCEDURES_pathSwitchRequest S1AP_ELEMENTARY_PROCEDURES_TVALUE The generated names include the name of the module object set and object in order to ensure that no name clashes occur between enumerations with common names For C this type is generated as a class with TVALUE as a public member inside class S1AP_ELEMENTARY PROCEDURES public enum TVALUE __UNDEF_ _handoverPreparation _handoverResourceAllocation _pathSwitchRequest 7 In this case the type module and object set names are not needed because the class name provides for unambiguous enumerated item names Generated Helper Methods For C special asniAppend_ lt name gt and asniGet IE_ lt name gt functions are generated to help a user append information elements IE s to a list and get an indexed IE respectively For C these are added as methods to the generated control class for the list type For example for the HandoverRequired_protocoliks type the following methods are added to the control class class EXTERN ASN1C_HandoverRequired_protocollIEs public ASN1CSeqOfList Append IE with value type ASNIT_MME_UE_S1AP_ID to list int Append_id_MME_UE_S1AP_ID ASN1T_MME _UE_S1AP_ID value
295. nstraint checks in code laxsyntax do not do a thorough ASN 1 syntax check list generate listing noContaining do not generate inline type for CONTAINING lt type gt nodecode do not generate decode functions noencode do not generat ncode functions noIndefLen do not generate indefinite length tests noObjectTypes do not gen types for items embedded in info objects noOpenExt do not generate open extension elements notypes do not generate type definitions noxmins do not generate XML namespaces for ASN 1 modules 0o lt directory gt set output file directory also srcdir lt dir gt libdir lt directory gt set output libraries directory bindir lt directory gt set output binary directory objdir lt directory gt set output object directory pdu lt type gt designate lt type gt to be a Protocol Data Unit PDU lt type gt may be all to select all type definitions usepdu lt type gt specify a Protocol Data Unit PDU type for which sample reader writer programs and test code has to be generated print lt filename gt generate print functions prtfmt details bracetext format of output generated by print shortnames reduce the length of compiler generated names syntaxcheck do syntax check only no code generation trace add trace diag msgs to generated code no UniqueNames resolve name clashes by generating unique names default on us noUniqueNames
296. ntext amp ctxt2 Populate apdu with test data OSCRTLMEMSET amp aarg 0 sizeof AarqApdu aarq assoc_version numbits 32 rtxSetBit aarq assoc_version data 32 AssociationVersion_assoc_versionl pDataProto rtxMemAllocType amp ctxt2 DataProto pDataProto gt data_proto_id data_proto_id_20601 pDataProto gt data_proto_info numocts len pDataProto gt data_proto_info data msgptr rtxDListAppend amp ctxt2 amp aarq data_proto_list pDataProto The msgptr variable is used here to fill in the contents of the data_proto_info structure The rest of the contents are initialized and then encoded apdu t T_ApduType_aarq apdu u aarg amp aarq Create memory output stream stat rtxStreamMemoryCreateWriter amp ctxt2 0 0 if stat lt 0 printf Create memory output stream failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt Encode stat MDEREnc_ApduType amp ctxt2 amp apdu Again a memory stream writer is used here for encoding but other options exist to write to a file or a socket Two phase Decoding Two phase decoding is the reverse operation of two phase encoding In this scenario a message is received and decoded The header and payload are contained in the message and the payload type and content must be decoded after the message is received This example shows how to decode the message encoded in the previous section As
297. o it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her or her program The value argument contains the value to be encoded or holds a pointer to the value to be encoded This variable is of the type generated from the ASN 1 production The object is passed by value 217 Generated C Encode Method Format and Calling Parameters if it is a primitive ASN 1 data type such as BOOLEAN INTEGER ENUMERATED etc It is passed using a pointer reference if it is a structured ASN 1 type value in this case the name will be pvalue instead of value Check the generated function prototype in the header file to determine how this argument is to be passed for a given function The elemName and attributes arguments are used to pass the XML element name and attributes respectively The elemName argument is the name that will be included in the lt name gt lt name gt brackets used to delimit an XML item There are three distinct ways this argument can be specified 1 If it contains standard text this text will be used as the element name 2 If itis null a default element name will be applied Default names for all of the built in ASN 1 types are defined in the 2002 X 680 standard For example lt BOOLEA N gt is the default element name for the BOOLEAN built in type 6699 3 If the name is empty i e equal to a zero length
298. object This is the same as in the legacy model The open type field element3 would be expanded into the union structure as is shown The lt Se lectorEnumType gt would be an enumerated type that is generated to represent each of the choices in the referenced information object set The union then contains an entry for each of the possible types as defined in the object set that can be used in the open type field Comments are used to list the fixed type fields corresponding to each open type field An example of the code that is generated from the S1AP sample ASN 1 snippet above is as follows typedef enum T_S1AP_PDU_Descriptions_S1AP_EL ARY_PROCE T_S1AP_PDU_Descriptions_S1AP_EL Z ARY_PROCE T_S1AP_PDU_Descriptions_S1AP_E CLS ys SLAP_EL DURE EMENTARY_PROCE typedef struct InitiatingMessage ProcedureCode procedureCode Criticality criticality information object Bef selector _TVALUE S1AP_ELE TARY_PROCEDURE _TVALUE S1AP E 2y union EMENTARY PROCE DURE t procedureCod criticality x7 HandoverRequired reject ARY_PROCE id HandoverPreparation handoverPreparation procedureCod criticality xj HandoverRequest reject procedureCod criticality X7 HandoverNotify ignore id Hand
299. object if exists In most cases it is only necessary to implement the following functions rtxMemHeapAlloc rtxMemHeapAllocZ rtxMemHeapFreePtr and rtxMemHeapRealloc Note that there is no analog in standard memory management for ASNIC s rtxMemFree macro i e the rtxMemHeapFreeAll function A user would be responsible for freeing all items in a generated ASNIC structure indi vidually if standard memory management is used The rtxMemHeapCreate and rtxMemHeapRelease functions are specialized functions used when a special heap is to be used for allocation for example a static block within an embedded system In this case r xMemHeapCreate must set the ppyMemHeap argument to point at the block of memory to be used This will then be passed in to all of the other memory management functions for their use through the OSCTXT structure The rx MemHeapRelease function can then be used to dispose of this memory when it is no longer needed To add these definitions to an application program compile the C source file it can have any name and link the resulting object file OBJ or O in with the application Built in Compact Memory Management A built in version of the simple memory management API described above i e with direct calls to malloc free etc is available for users who have the source code version of the run time The only difference in this API with what is described above is that tracking of allocated mem ory is done thro
300. ocInfo data_req_ mode_capab data_req_init_manager_count 0 ze ge Create memory output stream stat rtxStreamMemoryCreateWriter amp ctxt 0 0 if stat lt 0 printf Create memory output stream failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat Encode stat MDEREnc_PhdAssociationInformation amp ctxt amp phdAssocInfo msgptr rtxStreamMemoryGetBuffer amp ctxt amp len In brief the data structures used for the payload are initialized to zero using the oscRTLME MSE T macro which here acts just like the C runtime library memset function The data used for populating this example are taken from a draft specification After filling in the necessary fields the rtxstreamMemoryCreateWriter function is used to create a memory stream for encoding the payload More information on this function can be found in the C C Common Run Time Library manual In case of failure errors are trapped and reported Finally the proper mpEREnc function is called to encode the data A pointer to the message content is retrieved using the rtxStreamMemoryGetBuffer function This pointer is used later to fill in the contents of the payload 213 Two phase Decoding After encoding the payload the rest of the message content must be populated and encoded Initialize 2nd context structure stat rtInitCo
301. od must be used if C code generation was done This method can also be used as an alternative to using the control class interface if C code generation was done Before any decode function can be called the user must first initialize a context variable This is a variable of type OSCTXT This variable holds all of the working data used during the decoding of a message The context variable is declared as a normal automatic variable within the top level calling function It must be initialized before use This can be accomplished as follows OSCTAT ctxt int stat stat mderInitContext amp ctxt if stat 0 rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat The next step is to create a stream reader that will read from the given source In our example we read from a file but it is also possible to read data from a socket or other source as well A decode function can then be called to decode the message If the return status indicates success the C variable that was passed as an argument will contain the decoded message contents Note that 210 Decoding a Series of Messages Using the C Decode Functions the decoder may have allocated dynamic memory and stored pointers to objects in the C structure After processing on the C structure is complete the run time library function rtxmemF ree should be called to free the allocated memory A program fragment that could be used to decode a simple PDU ty
302. ode both the header and payload They must therefore be declared with the rest of the pertinent variables ApduType apdu AargApdu aard DataProto pDataProto PhdAssociationInformation phdAssocInfo OSCTXT ctxt ctxt2 OSOCTET msgptr int len const char filename message dat 212 Two phase Encoding We first populate and encode the payload specific details will vary depending on the application Populate and encode PhdAssociationInformation OSCRTLMEMSET amp phdAssocInfo 0 sizeof phdAssocInfo phdAssociInfo protocol_version numbits 32 phdAssociInfo protocol_version data 0 0x40 phdAssociInfo encoding_rules numbits 16 rtxSetBit phdAssocInfo encoding_rules data 16 EncodingRules_mder hdAssociInfo nomenclature_version numbits 32 rtxSetBit phdAssocInfo nomenclature_version data 32 NomenclatureVersion_nom_versionl 5 phdAssocInfo functional_units numbits 32 phdAssocInfo system_type numbits 32 rtxSetBit phdAssocInfo system_type data 32 SystemType_sys_type_agent static const OSOCTET sysId 0x317 0x32 0x33 0x34 0x35 0x36 0x37 0x38 5 phdAssocinfo system_id numocts OSUINT32 8 phdAssociInfo system_id data OSOCTET sysId p hdAssocInfo dev_config_id extended_config_start phdAssocInfo data_req_ mode_capab data_req_ mode_flags numbits hdAssocInfo data_req_ mode_capab data_req_init_agent_count 1 hdAss
303. ode operation will be placed in the variable declared in step 2 4 Invoke the ASN1C_ lt ProdName gt object Decode method 5 Check the return status The return value is a status value indicating whether decoding was suc cessful or not Zero 0 indicates success If decoding failed the status value will be a negative 197 Procedure for Using the C Control Class Decode Method number The decode buffer method PrintErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred 6 Release dynamic memory that was allocated by the decoder All memory associated with the decode context is released when both the ASN PERDecodeBuffer and ASNIC_ lt ProdName gt objects go out of scope A program fragment that could be used to decode an employee record is as follows include employee h include fil main OSOCTET msgbuf 1024 int msglen stat OSBOOL aligned TRUE logic to read message into msgbuf generated by ASNI1C step 1 instantiate a PER decode buffer ASNIPERDecodeBuffer decodeBuffer msgbuf step 2 instantiate an ASN1T_ lt ProdName gt ASN1T_PersonnelRecord msgData msglen step 3 instantiate an ASN1C_ lt ProdName gt ASN1C_PersonnelRecord employ decodeBuff step 4 decode the record stat employee Decod Os step 5 check the return status if stat 0 process received data else
304. oded back to back it is necessary to advance the buffer pointer in each iteration main OSOCTET msgbuf 1024 ASNITAG msgtag int offset 0 msglen len OSCTXT ctxt PersonnelRecord employee FILE fp Step 1 Initialize a context variable for decoding if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n 168 Generated C Decode Method Format and Calling Parameters return 1 if fp fopen filename rb msglen fread msgbuf 1 sizeof msgbuf fp else handle error for offset lt msglen xd_setp amp ctxt msgbuf offset msglen offset amp msgtag amp len Decode if tag TV_PersonnelRecord Call compiler generated decode function stat asnlD_PersonnelRecord amp ctxt amp employee ASNI1EXPL 0 if stat 0 decoding successful data in employee else error handling return 1 else printf unexpected tag hx received n tag offset ctxt buffer byteIndex rtxMemReset amp ctxt Generated C Decode Method Format and Calling Parameters Generated decode functions are invoked through the class interface by calling the base class Decode method The calling sequence for this method is as follows status lt object gt Decod Che I
305. oding is done the contents of the array will be adjusted to indicate the order the elements were received in xsd choice and xsd union The xsd choice type is converted to an ASN 1 CHOICE type ASNIC generates exactly the same code For example lt xsd complexType name NamePart gt lt xsd choice gt lt xsd element name givenName type xsd string gt lt xsd element name initial type xsd string gt lt xsd element name familyName type xsd string gt lt xsd choice gt lt xsd complexType gt in this case the generated code is the same as for ASN 1 CHOICE define T_NamePart_givenName 1 define T_NamePart_initial 2 define T_NamePart_familyName 3 typedef struct EXTERN NamePart int t union fA ES Ley const OSUTF8CHAR givenName t 2 const OSUTF8CHAR initial LEE 3 const OSUTF8CHAR familyName u 100 Repeating Groups NamePart Similar to xsd choice is xsd union The main difference is that xsd union alternatives are unnamed As specified in X 694 special names are generated in this case using the base name alt The generated name for the first member is alt names for successive members are alt n where n is a sequential number starting at 1 An example of this naming is as follows lt xsd simpleType name MyType gt lt xsd union memberTypes xsd int xsd language gt lt xsd simpleType gt This generates the following C
306. oding or decoding capabilities for example if it is only intended to read messages and does not need to write them unchecking the corresponding checkbox will reduce the amount of code generated Check Stream to modify generated encode and decode functions to use streams instead of memory buffers This allows encoding and decoding to a source or sink such as a file or socket Stream based encoding and decoding cannot be combined with buffer based As an aid to debugging Print functions may also be generated Three different different types exist print to stdout print to string and print to stream These allow the contents of generated types to be printed to the standard output a string or a stream such as a file or socket Constraint checking may be relaxed or tightened depending on selected options Constraints may be ignored completely by checking Do not generate constraint checks To tighten constraints check Enable strict constraint checks ASN1C supports decoding and encoding values described by table constraints checking Generate code to handle table constraints will enable this behavior This option is a legacy option for C and C code generation generating table constraints in unions is the preferred method see the following section 25 Common Code Generation Options To reduce the code footprint several other options may be selected Generate compact code Do not generate indefinite length processing code Do not
307. ods defined in the ASN1CType base class can be used with this construction form to encode and decode to the associated buffer The constructor arguments are a reference to an ASNI MessageBufferIF message buffer interface type and a reference to an ASNIT_ lt name gt type The message buffer interface argument is a ref erence to an abstract message buffer or stream class Implementations of the interface class are available for BER DER PER or XER encode or decode message buffers or fora BER or XER encode or decode stream The ASNIT_ lt name gt argument is used to specify the data variable containing data to be encoded or to receive data on a decode call The procedure for encoding is to declare a variable of this type populate it with data and then instantiate the ASN C_ lt name gt object to associate a message buffer object with the data to be encoded The Encode or Encode To method can then be called to encode the data On the decode side a variable must be declared and passed to the constructor to receive the decoded data Note that the ASN C_ class declarations are only required in the application code as an entry point for encoding or decoding a top level message or Protocol Data Unit PDU As of ASNIC version 5 6 control classes are only generated for ASN 1 types that are determined to be PDU s A type is determined to be a PDU if it is referenced by no other types This differs from previous versions of ASNIC where control classes w
308. odule gt Compare c If an output filename is specified after the genCompare qualifier all func tions are written to that file The format of the name of each generated compare function is as follows asnlCompare_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each generated compare function is as follows OSBOOL asnlCompare_ lt name gt const char name lt name gt pvalue lt name gt pCmpValue char errBuff int errBufSize 244 Generated Copy Functions In this definition lt name gt denotes the prefixed production name defined above The name argument is used to hold the top level name of the variable being compared It is typically set to the same name as the pvalue argument in quotes for example to compare employee records a call to asnlCompare_Employee employee amp employee etc might be used The pvalue argument is used to pass a pointer to a variable of the item to the first item to be compared The pCmpValue argument is used to pass the second value The two items are then compared field b
309. of message msgptr encodeBuffer getMsgPtr else error processing The encoding procedure for C requires one extra step This is a call to the module initialization functions after context initialization is complete All module initialization functions for all modules in the project must be invoked The module initialization function definitions can be found in the lt ModuleName gt Table h file The format of each module initialization function name is as follows void lt ModuleName gt _init OSCTXT pctxt Here ModuleName would be replaced with name of the module A C program fragment that could be used to encode the Invoke record defined above is as follows include TestTable h include file generated by ASNIC int main OSOCTET msgbuf 1024 msgptr int msglen OSCTXT CEES Invoke invoke typedef generated by ASNIC Step 1 Initialize the context and set the buffer pointer if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 xe_setp amp ctxt msgbuf sizeof msgbuf 136 General Procedure for Ta ble Constraint Decoding step 2 call module initialization functions Test_init amp ctxt Step 3 Populate the structure to b ncoded msgData opcode numids msgData opcode subid 0 0 msgData opcode subid 1 1 msgDa
310. of message received note this is optional the decode function can be called directly if the type of message is known 167 Generated C Function For mat and Calling Parameters Now switch on initial tag value to determine what type of message was received switch msgtag case TV_PersonnelRecord compiler generated constant status asnlD_PersonnelRecord amp ctxt amp employee ASNIEXPL 0 if status 0 decoding successful data in employee process received data else error processing break default handle unknown message type here switch Need to reinitialize objects for next iteration rtxMemReset amp ctxt The only changes were the addition of the for loop and the call to rtx MemReset that was added at the bottom of the loop This function resets the memory tracking parameters within the con text to allow previously allocated memory to be reused for the next decode operation Optionally rtxMemFree can be called to release all memory This will allow the loop to start again with no outstanding memory allocations for the next pass The example above assumes that logic existed that would read each message to be processed into the same buffer for every message processed inside the loop i e the buffer is reused each time In the case in which the buffer already contains multiple messages enc
311. of tags required If performance is not a significant issue then dynamic buffer allocation is a good alternative Set ting the buffer pointer argument to NULL in the call to xe_setp specifies dynamic allocation This tells the encoding functions to allocate a buffer dynamically The address of the start of the message is obtained as before by calling xe_getp Note that this is not the start of the allocated memory that is maintained within the context structure To free the memory either the rt MemFree function may be used to free all memory held by the context or the xe_free function used to free the encode buffer only The following code fragment illustrates encoding using a dynamic buffer include employee h include file generated by ASNIC main OSOCTET msgptr int msglen OSCTXT CEXtF Employee employee typedef generated by ASNIC if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 xe_setp amp ctxt NULL 0 mployee name givenName SMITH msglen asnlE_Employee amp ctxt amp employee ASNIEXPL if msglen gt 0 msgptr xe_getp amp ctxt rtxMemFree amp ctxt don t call free msgptr 152 Generated C Function For mat and Calling Parameters else error processing Encoding a Series of Messages Using
312. ointer to a variable to hold the decoded result This variable is of the type generated from the ASN 1 production The decode function will automatically allocate dynamic memory for variable length fields within the structure This memory is tracked within the context structure and is released when the context structure is freed 223 Procedure for Calling C Decode Functions The function result variable stat returns the status of the decode operation Status code zero indi cates the function was successful A negative value indicates decoding failed Return status values are defined in the rtxErrCodes h include file The reason text and a stack trace can be displayed using the rtxErrPrint function Procedure for Calling C Decode Functions This section describes the step by step procedure for calling a C XER decode function This method must be used if C code generation was done This method cannot be used as an alternative to using the control class interface if C code generation was done Use the C procedure instead There are four steps to calling a compiler generated decode function 1 Prepare a context variable for decoding 2 Open a stream 3 Call the appropriate compiler generated decode function to decode the message 4 Free the context after use of the decoded data is complete to free allocated memory structures Before a C XER decode function can be called the user must initialize a context variable This is a varia
313. ollowing type declaration typedef const char SecurityKeyType The SecurityKeyType variable can now be populated with a hexadecimal string for encoding such as the following SecurityKeyType secKey 0xfd09874da875cc90240087cd12fd Note that in this definition the ox prefix is required to identify the string as containing hexadecimal characters On the decode side the decoder will populate the variable with the same type of character string after decoding There are also a number of run time functions available for big integer support This set of func tions provides an arbitrary length integer math package that can be used to perform mathematical operations as well as convert values into various string forms See the ASNJC C C Common Run time User s Manual for a description of these functions BIT STRING The ASN 1 BIT STRING type is converted into a C or C structured type containing an integer to hold the number of bits and an array of unsigned characters OCTETs to hold the bit string contents The number of bits integer specifies the actual number of bits used in the bit string and takes into account any unused bits in the last byte The type definition of the contents field depends on how the bit string is specified in the ASN 1 definition If a size constraint is used a static array is generated otherwise a pointer variable is 45 BIT STRING generated to hold a dynamically allocated string The decoder w
314. ollows include employee h include file generated by ASNIC main OSOCTET msgbuf 4096 int msglen stat OSCTXT ctxt OSBOOL cxer FALSE canonical XER flag OSBOOL aligned TRUE Employee employee typedef generated by ASNIC Initialize context and set encode buffer pointer if rtInitContext amp ctxt 0 rtxErrPrint amp ctxt return 1 xerSetEncBufPtr amp ctxt msgbuf sizeof msgbuf cxer Populate variable with data to be encoded mployee name givenName John Encode data stat asnlXE_Employee amp ctxt amp employee 0 0 if stat 0 msglen xerGetMsgLen amp ctxt else error processing rtFreeContext amp ctxt release the context pointer After encoding is complete msgbuf contains the XML textual representation of the data By de fault a UTF 8 encoding is used For the ASCII character set this results in a buffer containing nor 219 Procedure for Using the C Control Class Encode Method mal textual data Therefore the contents of the buffer are represented as a normal text string and can be displayed using the C printf run time function or any other function capable of displaying text Procedure for Using the C Control Class En code Method The procedure to encode a message using the C class interface is as follows 1 Instantiate an ASN 1 X
315. om previous step Vv Final encoded message On the decode side the process would be reversed with the message flowing up the stack ROSE Layer 1 At the ROSE layer the header would be decoded producing information on the OPERATION type based on the MACRO definition and message type Invoke Result etc The invoke identifier would also be available for use in session management In our example we would know at this point that we got a login invoke request N Based on the information from step 1 the ROSE layer would know that the Open Type field contains a pointer and length to an encoded Login ARGUMENT component It would then route this information to the appropriate processor within the Application Layer for handling this type of message Oo The Application Layer would call the specific decoder associated with the Login ARGUMENT It would then have available to it the username password the user is logging in with It could then do whatever applicationspecific processing is required with this information database lookup etc 4 Finally the Application Layer would begin the encoding process again in order to send back a Result or Error message to the Login Request A picture showing this is as follows Application Layer Call specific function to decode Login ARGUMENT and process data A Encoded message pointer and length Decode ROSE header message structure Invoke Open type structure contains message poin
316. on an EncodeFrom and DecodeTo method is generated within the generated class structure These are standard methods that initialize context information and then call the generated C like encode or decode function If the generation of print functions was specified by including print on the compiler command line a Print method is also generated that calls the C print function For XER additional methods are generated to implement a SAX content handler interface to an XML parser This includes a startElement characters and endElement method An init and finalize method may also be generated to initialize a variable prior to parsing and to complete population of a variable with decoded data Generated Information Object Table Structures Information Objects and Classes are used to define multi layer protocols in which holes are de fined within ASN 1 types for passing message components to different layers for processing These items are also used to define the contents of various messages that are allowed in a particular ex change of messages The ASN1C compiler extracts the types involved in these message exchanges and generates encoders decoders for them The holes in the types are accounted for by adding open type holders to the generated structures These open type holders consist of a byte count and pointer for storing information on an encoded message fragment for processing at the next level The ASNIC compiler is capable of
317. on an additional method is generated for an optional field as follows OSBOOL is lt FieldName gt Present if m lt FieldName gt Present return TRUE else return FALSE This function is used to check if the field value is present in an information object definition Generation of New ASN 1 Assignments from CLASS Assignments During CLASS definition code generation the following new assignments are created for C or C code generation 1 Anew Type Assignment is created for a TypeField s type definition as follows _ lt ClassName gt _ lt FieldName gt lt Type gt Here className is replaced with name of the Class Assignment and FieldName is replaced with name of this field Type is the type definition in CLASS s TypeField This type is used as a defined type in the information object definition for an absent value of the TypeField It is also useful for generation of a value for a related Open Type definition in a table constraint 2 Anew Type Assignment is created for a Value Field or Value Set Field type definition as follows if the type definition is one of the following ConstraintedType ENUMERATED NamedList BIT STRING SEQUENCE SET CHOICE SEQUENCE OF SET OF _ lt ClassName gt _ lt FieldName gt lt Type gt Here className is replaced with the name of the CLASS assignment and FieldName is replaced with name of the ValueField or ValueSetField type is the type definition in the CL
318. onst Complex types i e classes or structs with non trivial constructors will be marked as WSD whether marked const or not It is common in generated code to use lookup tables for some types e g ENUMERATED These tables are composed of simple types and marked as const to avoid being marked as WSD by Sym bian compilers Extern Linkage Most common compilers support applying external linkage to an entire class but Symbian s does not Symbian also requires that both prototype and implementation be marked with the appropriate linkage When the symbian option is specified generated code is modified to accommodate these requirements The following specification will demonstrate the differences between code generated with Symbian and without Test DEFINITIONS BEGIN A NULL END The usual class definition for this specification looks like this class EXTERN ASNIC_A public ASN1CType protected public ASNIC_A ASN1C_A OSRTMessageBufferIF amp msgBuf ASN1C_A OSRTContext amp context standard encode decode methods defined in ASN1CType base class int Encode int Decode stream encode decode methods int EncodeTo OSRTMessageBufferIF amp msgBuf int DecodeFrom OSRTMessageBufferIF amp msgBuf 5 It is very similar to the Symbian class definition class ASNIC_A public ASN1CType protected public EXTERN ASNIC_A
319. orm of these function calls to create a writer interface to a file memory or socket stream e rtxStreamFileCreateWriter e rtxStreamMemoryCreate Writer e rtxStreamSocketCreateWriter After initializing the context and populating a variable of the structure to be encoded an encode function can be called to encode the message to the stream The stream must then be closed by calling the rtxStreamClose function A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNIC int main int stat OSCTXT ctxt Employee employee typedef generated by ASNIC 159 Generated Streaming C Function Format and Calling Parameters const char filename message dat Step 1 Initialize the context and stream if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 Step 2 create a file stream object within the context stat rtxStreamFileCreateWriter amp ctxt filename if stat 0 rtxErrPrint amp ctxt return stat Step 3 Populate the structure to b ncoded mployee name SMITH Step 4 Call the generated encode function stat asnlBSE_Employee amp ctxt amp employee ASNI1EXPL Step 5 Check the return status an
320. other utility methods to make populat ing the typed variable object easier ASNIC always adds an ASN C_prefix to the production name to form the class name Most gen erated classes are derived from the standard ASN1CType base class defined in asn1 Message h The following ASN 1 types cause code to be generated from different base classes e BIT STRING The generated control class is derived from the ASNI CBitStr class e SEQUENCE OF or SET OF with linked list storage The generated control class is derived from the ASN CSeqOfList base class Defined Type The generated control class for defined types is derived from the generated base class for the reference type For example if we have A INTEGER and B A then B is a defined type and would inherit from the base class generated for A class ASN1C_B public ASNIC_A 113 Generated C Source Files These intermediate classes are also derived from the ASN CType base class Their purpose is the addition of functionality specific to the given ASN 1 type For example the ASNI CBitStr control class provides methods for setting clearing and testing bits in the referenced bit string variable In the generated control class the msgData member variable is a reference to a variable of the generated type The constructor takes two arguments an Asn MessageBufferlF message buffer interface object reference and a reference to a variable of the data type to be encode
321. overNotification handoverNotification DUR ES_handoverPreparation DUR ES_handoverResourceAllocation DUR information objects handoverResourceAllocation ES_pathSwitchRequest id HandoverResourceAllocation 83 Unions Table Constraint Model u InitiatingMessage Note that the long names generated in the SLAP_ELEMENTARY_PROCEDURE_TVALUE type can be reduced by using the lt alias gt configuration element Generated C Type Definitions for Information Element IE Types In addition to message types another common pattern in 3GPP specifications is protocol informa tion element IE types The general form of these types is a list of information elements as follows lt ProtocollEsType gt lt ProtocolIE ContainerType gt lt ObjectSet gt lt ProtocolIE ContainerType gt lt Class gt lt ObjectSetParam gt SEQUENCE SIZE lt size gt OF lt ProtocollIE FieldType gt ObjectSetParam lt ProtocollIE FieldType gt lt Class gt lt ObjectSetParam gt SEQUENCE lt elementl gt lt Class gt amp lt fixed type field gt ObjectSetParam lt element2 gt lt Class gt amp lt fixed type field gt ObjectSetParam element1l lt element3 gt lt Class gt amp lt Type field gt ObjectSetParam element1 There are a few different variations of this but the overall pattern is similar in all cas
322. oyee const char filename message dat Step 1 Initialize a context variable for decoding if berStrmInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 Step 2 Open the input stream to read data stat rtxStreamFileCreateReader amp ctxt filename if stat 0 rtxErrPrint amp ctxt return stat for 7 Step 3 Test message tag for type of message received note this is optional the decode function can be called directly if the type of message is known if stat berDecStrmPeekTagAndLen amp ctxt amp tag amp len 0 rtxErrPrint amp ctxt return stat if msgtag TV_PersonnelRecord Step 4 Call decode function note last two args should always be ASNIEXPL and 0 181 Generated Streaming C Decode Method Format and Calling Parameters stat asnlBSD_PersonnelRecord amp ctxt amp employee ASNIEXPL 0 Step 5 Check return status if stat 0 process received data in employee variable else error processing else check for other known message types Need to reset all memory for next iteration rtxMemReset amp ctxt end of loop Step 6 Close the stream rtxStreamClose amp ctxt Remember to release dy
323. p rriective SYSTEMS INC ASNIC ASN 1 Compiler Version 6 4 C C User s Guide Objective Systems Inc February 2011 The software described in this document is furnished under a license agreement and may be used only in accordance with the terms of this agreement Copyright Notice Copyright 1997 2011 Objective Systems Inc All rights reserved This document may be distributed in any form electronic or otherwise provided that it is distributed in its entirety and that the copyright and this notice are included Author s Contact Information Comments suggestions and inquiries regarding ASN1C may be submitted via electronic mail to info obj sys com Table of Contents Overview o ASNIC wie ie Geta eel ee ae ell eee es 1 Using the Comprei seiri e decease ne Aare eae aati teeta Gets eee 3 Running ASNIC from the Command line sesesseeseeeeseeesesresseseresressereresressrssrestessessresresseese 3 Using the GUI Wizard to Run ASNIC sessessssssessssrsesssssressessssssessesssssnesseesseserssessassssresses 20 USMO ETOCS ar t a r E E eae wae as vate eines E 20 Common Code Generation Options ssssssssesessseessssesssetsseesseesseesssetesseesseesseesseeessees 23 XSD OPU ONS ces 2a dro EE dpc lade ahaa ea scsi A E nO dag EOE Oe hi 27 C C Code Generation Options anaiAiievncsca dees eee ere eean eee 27 Compilations ersen ea San Buhay a a E a A E weg cee er Ae 29 Compiling and Linking Generated Code
324. parse errors maxcfiles None Maximize number of generated C files This op tion instructs the compiler to generate a sepa rate c file for each generated C function In the case of C a separate cpp file is generated for each control class type and C function This is a space optimization option it can lead to smaller executable sizes by allowing the linker to only link in the required program module object files 13 Running ASNIC from the Command line Option Argument Description maxlines mder lt number gt None This option is used to specify the maximum number of lines per generated c or cpp file If this number is exceeded a new file is started with a _n suffix where n is a sequential num ber The default value if not specified is 50 000 lines which will prevent the VC Maximum line numbers exceeded warning that is common when compiling large ASN 1 source files Note that this number is approximate the next file will not be started until this number is ex ceeded and the compilation unit that is currently being generated is complete This option instructs the compiler to generate functions that implement the Medical Device Encoding Rules MDER as specified in the IEEF ISO 11073 standard mt None When used in conjunction with the genMake command line option the generated makefile uses multi threaded libraries nmake lt filename g
325. pe follows include ISO 11073 20601 ASN1 h include file generated by ASNI1C int main void ApduType data OSCTXT CEXE const char filename message dat int stat Step 1 Initialize a context variable for decoding stat mderInitContext amp ctxt if stat 0 initialization failed could be a license problem rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat Step 2 Initialize a stream reader stat rtxStreamFileCreateReader amp ctxt filename if 0 stat rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat Step 3 decode stat MDERDec_ApduType amp ctxt amp data if stat 0 printf decode of data failed n rtxErrPrint amp ctxt rtFreeContext amp ctxt return 1 Decoding a Series of Messages Using the C Decode Functions Decoding a series of messages is very similar to the method used for other encoding rules MDER however is simpler Users need not concern themselves with idiosyncrasies like byte alignment or length markers Short pseudo code is shown below As in the encoding example rtxMemreset is used at the end of the loop to avoid allocating new memory for dynamic data structures This helps to improve performance 211 Two Phase Messaging initialize context et c for d initialize data structure call mderDec_ lt name gt function
326. pecified is checked for a lt sourceFile gt element containing the name of the source file for the module Note that the lt oid gt configuration item can be used to distin guish modules that have the same names but different object identifiers 2 If this element is not present the compiler looks for a file with the name lt ModuleName gt asn where module name is the name of the module specified in the IMPORT statement In both cases the I command line option can be used to tell the compiler where to look for the files The other way of specifying multiple modules is to include them all within a single ASN 1 source file It is possible to have an ASN 1 source file containing multiple module definitions in which modules IMPORT definitions from other modules An example of this would be the following ModuleA DEFINITIONS BEGIN IMPORTS B From ModuleB A 33 gt B END oduleB DEFINITIONS BEGIN B INTEGER END This entire fragment of code would be present in a single ASN 1 source file 259 260 ROSE and SNMP Macro Support The ASNIC compiler has a special processing mode that contains extensions to handle items in the older 1990 version of ASN 1 i e the now deprecated X 208 and X 209 standards This mode is activated by using the asnstd x208 command line option Although the X 208 and X 209 standards are no longer supported by the ITU T they are still in use today This v
327. piler The only additional option that must be set is the inclusion of the ASN 1 C C header file include directory with the I option When linking a program with compiler generated code it is necessary to include the ASN 1 run time libraries It is necessary to include at least one of the encoding rules libraries asn1 ber asn1 per or asn1xer as well as the common run time functions library asnIrt See the ASNI C C C Run time Reference Manual for further details on these libraries For static linking on Windows systems the name of the library files are asn ber_a lib asnIper_a lib or asnIxer_a lib for BER DER CER PER XER or XML respectively and 30 Compiling and Linking Generated Code asnIrt_a lib for the common run time components On UNIX Linux the library names are libasn1ber a libasnIper a libasn1xer a libasn1xml a and libasnIrt a The library files are located in the lib subdirectory For UNIX the L switch should be used to point to the subdirectory path and lasnIber lasn1 per lasn1xer lasnlxml and or lasnIrt used to link with the libraries For Windows the LIBPATH switch should be used to specify the library path There are several other variations of the C C run time library files for Windows The following table summarizes what options were used to build each of these variations Library Files Description asnirt_a lib Static single threaded libraries These are built without MT asnlb
328. r cpp file along with all other generated functions If maxcfiles is specified each generated function is written to a separate c file The format of the name of each generated memory free function is as follows asnlFree_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each generated memory free function is as follows asnlFree_ lt name gt OSCTXT pctxt lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold the context pointer that the memory to be freed was allocated with This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her or her program The pvalue argument is used to pass a pointer to a variable of the item that contains the dynamic memory to be freed Generated Print Functions The following options are available for generating code to print the contents of
329. r functions are provided that allow the user to control the size increment of buffer expansions See the C C Run Time Library Reference Manual for a description of these functions In either case after a message is encoded it is necessary to get the start address and length of the message Even in the static buffer case the message start address may be different then the buffer start address see the section on encoding BER messages For this reason each set of encoding rules has a run time C function for getting the message start address and length See the C C Run Time Library Reference Manual for a description of these functions The C message buffer classes contain the getMsgPtr getMsgCopy and getMsgLength methods for this purpose A stream message buffer can be used for BER encoding This type of buffer is used when the stream option was used to generate the encode functions See the section on BER stream encoding for a complete description on how to set up an output stream to receive encoded data 147 148 Generated BER Functions Generated BER Encode Functions Note This section assumes standard memory buffer based encoding is to be done If stream based encoding is to be done specified by adding stream to the ASNIC command line see the Generated BER Streaming Encode Functions section for correct procedures on using the stream based encode functions For each ASN 1 production defined in the ASN 1 source
330. raries ASNIC by default does not include a stacktrace instead only an error code is provided These codes are described more fully in this appendix The descriptions are derived from the contents of rtxsrc rtxErrCodes h and rt src asniErrCodes h Users may always look at these two files or the documentation generated from them for a fully updated list of error messages and their descriptions ASN1C Error Messages The following table describes error messages that ASN1C may report during the course of code generation not during runtime These include syntax errors import warnings type resolution fail ures and others Users should note that there are several classes of status messages in this list errors asN E mes sages warnings AsN w messages and informational notices asn 1 messages Error Code Error Description ASN E NOTYPE ASN E UNDEFTYPE The type referenced was not defined within the context of No type was defined for the referenced element in a SE QUENCE or SET this module ASN E NOTAG The object must be tagged in this context This usually occurs when context specific tags are required to disam biguate elements in a SEQUENCE or SET ASN W DUPLICATE The referenced type or value was previously defined ASN W DUPLTAG ASN E UNRECTYP The type described is not recognized by the compiler The referenced tag was previously defined in a CHOICE or SET this happens wh
331. rated encode and decode function in the form of constraint checks xsd complexContent The xsd complexContent type is used to extend or restrict complex types in different ways It is similar to deriving types from base types in higher level programming languages such as C or Java A common usage pattern in the case of extension is to add additional elements to an existing sequence or choice group In this case a new type is formed that contains all elements those declared in the base definition and those in the derived type Also generated is a new type with the name lt baseType gt _derivations which is a choice of all of the different derivations of the base type This is used wherever the complex content base type is referenced to allow any derivation of the type to be used in a message An example of this is as follows lt xsd complexType name MyType gt lt xsd sequence gt lt xsd element name ElementOne type xsd string gt lt xsd element name ElementTwo type xsd int gt lt xsd sequence gt lt xsd complexType gt lt xsd complexType name MyExtendedType gt lt xsd complexContent gt lt xsd extension base MyType gt lt xsd sequence gt lt xsd element name ElementThree type xsd string gt lt xsd element name ElementFour type xsd int gt lt xsd sequence gt lt xsd extension gt lt xsd complexContent gt lt xsd complexType gt The base type in this case is MyType and it is exte
332. rated typedef names and function names for the production The calling sequence for each encode function is as follows status OEREnc_ lt name gt OSCTXT pctxt lt name gt value In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere in his or her program The value argument contains the value to be encoded or holds a pointer to the value to be encoded This variable is of the type generated from the ASN 1 production The object is passed by value if it is a primitive ASN 1 data type such as BOOLEAN INTEGER ENUMERATED etc It is passed using a pointer reference if it is a structured ASN 1 type value Check the generated function prototype in the header file to determine how the value argument is to be passed for a given function The function result variable stat returns the status of the encode operation Status code 0 0 in dicates the function was successful Note that this return value differs from that of BER encode 201 Populating Generated Struc ture Variables for Encoding functions in that the encoded length of the message component is not returned only an
333. re an integer larger than the C or C int type on the given system normally 32 bits A C string type char will be used to hold a textual representation of the value This qualifier can be applied to either an integer or constructed type If constructed all in teger elements within the constructed type are flagged as big integers lt isPDU gt n a This is a flag variable that specifies that this pro duction represents a Protocol Data Unit PDU This is defined as a production that will be en coded or decoded from within the application code This attribute only makes a difference in the generation of C classes Control classes that are only used in the application code are on ly generated for types with this attribute set lt storage gt lt storage gt dynamic static list ar ray or dynamicArray keyword The definition is the same as for the global case except that the specified storage type will only be applied to the generated C or C type for the given production lt typePrefix gt lt type prefix text Prefix gt Element Level This is used to specify a prefix that will be ap plied to all generated C and C typedef names note for C the prefix is applied after the standard ASN1T_ prefix This can be used to prevent name clashes if multiple modules are involved in a compilation and they all contain common names These attributes can be applied at the element leve
334. re complex then the other rules because XER requires the use of third party XML parser software This re quires the use of additional include directories when compiling and libraries when linking The C sample programs that are provided use the EXPAT XML parser http expat sourceforge net All of the necessary include files and binary libraries are included with the distribution for using this parser If a different parser is to be used consult the vendor s documentation for compile and link procedures See the makefile in any of the sample subdirectories of the distribution for an example of what must be included to build a program using generated source code 31 Porting Run time Code to Other Platforms Porting Run time Code to Other Plat forms The run time source version of the compiler includes ANSI standard source code for the base run time libraries This code can be used to build binary versions of the run time libraries for other operating environments Included with the source code is a portable makefile that can be used to build the libraries on the target platform with minimal changes All platform specific items are isolated in the platform mk file in the root directory of the installation The procedure to port the run time code to a different platform is as follows note this assumes common UNIX or GNU compilation utilities are in place on the target platform 1 Create a directory tree containing a root dire
335. received that contains something other than 1 or 0 characters ASN_E_BASE 4 ASN_E_INVINDEX Invalid table constraint index This error code is returned when a value is provided to index into a table and the value does not match any of the defined indexes ASN_E_BASE 5 ASN_E_INVTCVAL Invalid table constraint value This error code is returned when a the value for an element in a table constrained message instance does not match the value for the element defined in the table ASN_E_BASE 6 ASN_E_CONCMODF Concurrent list modification error This error is returned from within a list iterator when it is de tected that the list was modified outside the con trol of the iterator ASN_E_BASE 7 ASN_E_ILLSTATE Illegal state for operation This error is returned in places where an operation is attempted but the object is not in a state that would allow the op eration to be completed One example is in a list iterator class when an attempt is made to remove a node but the node does not exist ASN_E_BASE 8 ASN_E_NOTPDU This error is returned when a control class En code or Decode method is called on a non PDU Only PDUs have implementations of these methods ASN_E_BASE 9 ASN_E_UNDEFTYP Element type could not be resolved at run time This error is returned when the run time parser module is used AsnIRTProd to decode a type at run time and the type of the element could not
336. res for types that use table constraints are different than when table constraint code generation is not enabled These differences will be pointed out There are two models currently supported for table contraint generation Unions and Legacy These are documented in the following sections Unions Table Constraint Model The unions table constraint model originated from common patterns used in a series of ASN 1 specifications in use in 3rd Generation Partnership Project 3GPP standards These standards in clude Node Application Part B NBAP Radio Access Network Application Part RANAP and Radio Network Subsystem Application Part RNSAP in the current 3G network and in S1AP and X2AP protocols in the newer 4G network LTE standards This model was later extended to gen erate these type of structures for other specifications that made use of table constraints including security and legacy telecom speifications Generated C Type Definitions for Message Types The standard message type used by many specifications that employ table constraints is usually a SEQUENCE type with elements that use a relational table constraint that uses fixed type and type fields The general form is as follows lt Type gt SEQUENCE lt elementl gt lt Class gt amp lt fixed type field gt lt ObjectSet gt lt element2 gt lt Class gt amp lt fixed type field gt lt ObjectSet gt element1 lt element3 gt lt Class gt amp lt type f
337. riable length fields within the structure This memory is tracked within the context structure and is released when the context structure is freed The function result variable stat returns the status of the decode operation Status code 0 0 indi cates the function was successful A negative value indicates decoding failed Return status values are defined in the asnltype h include file The reason text and a stack trace can be displayed using the rtErrPrint function described later in this document Generated C Decode Method Format and Calling Parameters Generated decode functions are invoked through the class interface by calling the base class Decode method The calling sequence for this method is as follows status lt object gt Decod 0S In this definition lt object gt is an object of the class generated for the given production An ASNIPERDecodeBuffer object must be passed to the lt object gt constructor prior to decoding This is where the message start address and length are specified A Boolean argument is also passed indicating whether the message to be decoded was encoded using aligned or unaligned PER The function result variable status returns the status of the decode operation The return status will be zero 0 if decoding is successful or a negative value if an error occurs Return status values are documented in the C C Common Functions Reference Manual and in the rtxErrCodes h include file Procedure for
338. rintf rtInitContext failed check license n rtxErrPrint amp ctxt return stat pu_setBuffer amp ctxt 0 0 aligned if stat asnlPE_Employee amp ctxt amp employee 0 msgptr pe_GetMsgPtr amp ctxt amp msglen else error processing It is also possible to encode directly to a stream interface To do this the call to pu_setBuffer above would be replaced with a call to create a stream writer within the context such as rtxStreamFile Create Writer The call to the generated PER encode function would not change it will automati cally know to use the stream interface instead of a memory buffer Procedure for Using the C Control Class En code Method The procedure to encode a message using the C class interface is as follows 1 Instantiate an ASN 1 PER encode buffer object ASN 1PEREncodeBuffer to describe the buffer into which the message will be encoded Two overloaded constructors are available The first form takes as arguments a static encode buffer and size and a Boolean value indicating whether aligned encoding is to be done The second form only takes the Boolean aligned argument This form is used to specify dynamic encoding 2 Instantiate an ASN1IT_ lt ProdName gt object and populate it with data to be encoded 3 Instantiate an ASN1C_ lt ProdName gt object to associate the message buffer with the data to be encoded 190 Procedure for Using the C
339. rning message skip the element and continue As before the first step is to create a class derived from the Asn ErrorHandler base class This class is as follows class MyErrorHandler public AsnlErrorHandler public The error handler callback method This is the method that the user must override to provide customized error handling virtual int error OSCTXT pCtxt ASN1CCB pCCB int stat pa Simple enough All we are doing is providing an implementation of the error method Implementing the error method requires some knowledge of the run time internals In most cases it will be necessary to somehow alter the decoding buffer pointer so that the same field isn t looked at again If this isn t done an infinite loop can occur as the parser encounters the same error condition over and over again The run time functions xd_NextElement or xd_OpenType might be useful in the endeavor as they provide a way to skip the current element and move on to the next item Our sample handler corrects the error in which an unknown element is encountered within a SET construct This will cause the error status ASN_E_NOTINSET to be generated When the error handler sees this status it prints information on the error that was encountered to the console skips to the next element and then returns an O status that allows the decoder to continue If some other error occurred i e status was not equal to ASN_E_NOTINSET then the ori
340. roduction lt name gt ENUMERATED lt idl1 gt lt vall gt lt id2 gt lt val2 gt Generated code typedef enum idl vall id2 val2 lt name gt _Root typedef OSUINT32 lt name gt The compiler will automatically generate a new identifier value if it detects a duplicate within the source specification The format of this generated identifier is id_n where id is the original identifier and n is a sequential number The compiler will output an informational message when this is done This message is only displayed if the warnings qualifier is specified on the command line A configuration setting is also available to further disambiguate duplicate enumerated item names This is the enum prefix setting that is available at both the module and production levels For example the following would cause the prefix h225 to be added to all enumerated identifiers within the H225 module lt module gt lt name gt H225 lt name gt lt enumPrefix gt h225 lt enumPrefix gt lt module gt The fgenum fully qualified enum option may also be used to make C names unique When spec ified enumerated identifiers will be automatically prefixed with the enclosing type name In the specification above each of the identifiers would have the form lt name gt _ lt id gt This can be use ful in situations where common identifiers are often repeated in different types This is not a prob lem in C be
341. rs because the adapter layer within these libraries defines a common SAX API If an application is linked statically then the static variant of one of these interface objects their names have suffix _a should be linked cooperatively with the XML parser ASNIXER and ASNIRT libraries If the application is linked dynamically using dynamically linked libraries DLL in Windows or shared objects SO or SL in UNIX Linux then it is necessary to link the application with the dynamic variant of the interfaces without suffix _a dynamic version of the XML parser ASN1XER and ASNIRT dynamic libraries Generated XML Encode Functions XML C encode and decode functions are generated when the xml switch is specified on the com mand line These are similar to the XER encode functions described earlier Like XER this func tion allows data in a populated variable to be formatted into an XML document Unlike the XER 227 Generated XML Encode Functions variant this function will produce XML that adheres more closely to the Worldwide Web Consor tium W3C XML conventions In particular the following differences exist e Lists of numbers enumerated tokens and named bits are expressed in space separated list form instead of as individually wrapped elements or value lists For example the ASN 1 specification A SEQUENCE OF INTEGER with value 1 2 3 P would produce the following encoding in XER lt A gt lt INTEGE
342. rsonnelRecord msgData ASN1C_PersonnelRecord employ 77 d for msgData step 3 populate msgData structure with data to be encoded note this uses the generated assignment operator to assign a string msgData name step 4 out lt lt employee invoke lt lt EncodeTo SMITH operator or EncodeTo method out can be used here or employ step 5 if out getStatus fetch and check status TSO of printf Encoding failed Status i n out getStatus out printErroriInfo return 1 if trace printf Generated BER Decode Functions NOTE This section assumes standard memory buffer based decoding is to be done If stream based decoding is to be done specified by adding stream to the ASNIC command line see the Generated BER Streaming Decode Functions section for correct procedures on using the stream based functions Encoding was successful n For each ASN 1 production defined in an ASN 1 source file a C decode function is generated This function will decode an ASN 1 message into a C variable of the given type 164 Generated C Function For mat and Calling Parameters If C code generation is specified a control class is generated that contains a Decode method that wraps this function This function is invoked through the class interface to decode an ASN 1 message into the variable refer
343. s stream int EncodeTo int DecodeFrom ASN1MessageBufferIF amp msgBuf ASN1MessageBufferIF amp msgBuf SAX Content Handler Interface virtual void s const const const const XMI XMI XMI At virtual void const XMI virtual void cons cons cons t ct ct XMI XMI XMI LC LC LC c LC LC LC LC h h h h h h h tartElement const uri const localname const qname tributes amp attrs haracters const chars const unsigned int length endElement const uri const localname const qname The main differences between the BER DER PER control class definition and this are 1 The class generated for XER inherits from the ASN XERSAXHandler base class and 126 Generated Methods 2 The class implements the standard SAX content handler methods This allows an object of this class to be registered as a SAX content handler with any SAX com pliant XML parser The parser would be used to read and parse XML documents The methods generated by ASN1C would then receive the parsed data via the SAX interface and use the results to populate the data variables with the decoded data Note that for XML code generation xml command line option the SAX handler interface is not generated That is because XML decoders use a pull parser instead of SAX code to parse the XML input stream Generated Methods For each producti
344. s for each module in the source file The format of the name of each file is lt module gt PrtToStr c If an output filename is specified after the genPrtToStr qualifier all functions are written to that file The calling sequence for each generated print to string function is as follows 241 Print to Stream asnlPrtToStr_ lt name gt const char name lt name gt pvalue char buffer int bufSize The name and pvalue arguments are the same as they were in the print case The buffer and bufSize arguments are used to describe the memory buffer the text is to be written into These arguments specify a fixed size buffer If the generated text is larger than the given buffer size as much text as possible is written to the buffer and a 1 status value is returned If the buffer is large enough to hold the text output all text is written to the buffer and a zero status is returned If there is text already in the buffer the function will append to this text rather than overwrite it starting at the first null character So in this case there must be enough space in the buffer starting from the first null character to hold all of the generated text otherwise a status of 1 is returned For this reason initializing a newly allocated buffer with zeroes before passing it to the function is a good idea For C two toString methods are generated in the control class that call the generated print to string function With the first s
345. s information is not present is because we are just interested in showing the items that the compiler is concerned with We will use this type to demonstrate the simple form of code generation We will then add table constraints and discuss what changes when the tables command line options is used The opcode field within this definition is an example of a fixed type field reference It is known as this because if you go back to the original class specification you will see that operationCode is defined to be of a specific type namely a choice between a local and global value The generated typedef for this field will contain a reference to the type from the class definition 128 Simple Form Code Generation The argument field is an example of a variable type field In this case if you refer back to the class definition you will see that no type is provided This means that this field can contain an instance of any encoded type note in practice table constraints can be used with Information Object Sets to limit the message types that can be placed in this field The generated typedef for this field contains an open type ASN OpenType reference to hold a previously encoded component to be specified in the final message Simple Form Code Generation In the simple form of information object code generation the Invoke type above would result in the following C or C typedefs being generated typedef struct Invoke SE
346. s initialized by calling the rt nitContext function The user then has the option to do stream based or memory based decoding If stream based is to be done the user must call a rtxStreamCreateReader function for the type of stream from which data will be read For example if the user wishes to read data from a file the rtxStreamFileCreateReader function would be called To do memory based decoding the rtx nitContextBuffer function would be called The message to be decoded must reside in memory The arguments to this function would then specify the message buffer in which the data to be decoded exists The variable that is to receive the decoded data must then be initialized This can be done by either initializing the variable to zero using memset or by calling the ASNIC generated initialization function A decode function can then be called to decode the message If the return status indicates success 0 then the message will have been decoded into the given ASN 1 type variable The decode function may automatically allocate dynamic memory to hold variable length variables during the course of decoding This memory will be tracked in the context structure so the programmer does not need to worry about freeing it It will be released when the either the context is freed or explicitly when the rtxMemFree or rtxMemReset function is called The final step of the procedure is to free the context block This must be done regardless of whether
347. s is ignored when tagging is set to ASNJEXPL explicit so users can ignore it for the most part and set it to zero In the implicit case this speci fies the number of octets to be extracted from the byte stream This is necessary because implicit indicates no tag length pair precedes the data therefore it is up to the user to indicate how many bytes of data are present If PER encoding is specified the format of the generated prototypes is different The PER proto types are of the following general form int asnlPE_ lt ProdName gt OSCTXT pctxt lt ProdName gt value int asnlPD_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue In these prototypes the prefixes are different a P character is added to indicate they are PER encoders decoders and the tagging argument variables are omitted In the encode case the value of the production to be encoded may be passed by value if it is a simple type for example BOOLEAN or INTEGER Structured values will still be passed using a pointer argument If XER encoding is specified function prototypes are generated with the following format 123 Generated C Control Class Definition int asnlXE_ lt ProdName gt OSCTXT pctxt lt ProdName gt value const char elemName const char attributes int asnlXD_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue The encode function signature includes arguments for the context and val
348. s provide a smart alternative to memset ing in that only what needs to be set to zero actually is Note that previous versions of ASNIC did not generate initialization functions by default The genlnit switch has been deprecated in favor of nolnit noEnumConvert None This option suppresses the generation of utility functions in C and C that assist in convert ing enumerated values to strings and vice versa XER and XML encodings are unaffected by this option since conversions are necessary for en coding and decoding noObjectTypes None This option suppresses the generation of appli cation language types corresponding to ASN 1 types embedded within information object defi nitions noOpenExt None This option instructs the compiler to not add an open extension element extE em in constructs that contain extensibility markers The purpose of the element is to collect any unknown items in a message If an application does not care about these unknown items it can use this option to reduce the size of the generated code notypes None This options suppresses the generation of type definitions It is used in conjunction with the events options to generate pure parser functions noxmlns None This option instructs the compiler not to insert XML namespace entries in generated XML doc uments This includes xmins attributes and pre fixed names nouniquenames None
349. s the linker to link in only the required functions as opposed to all functions in a compiled object module This option might be useful for applications that have minimal space requirements for example embedded systems Note Some sophisticated linkers have the capability to pull individual functions out of an object module directly for final inclusion in the target executable or shared object file In this case the maxcfiles option does not provide any advantage in reducing the size of the application program 115 Generated C files To achieve the best results it is necessary to put all compiled object files into an object library a or lib file and include this library in the link command The genMake option when used in conjunction with maxcfiles will generate a makefile that will compile each of the generated files and add them to a library with a name based on the name of the ASN 1 module being compiled lt moduleName gt lib for Windows or lib lt moduleName gt a for NIX The format of each generated c file name is as follows asnl lt suffix gt _ lt prodname gt c where lt suffix gt depends on encoding rules and the function type encode decode free etc and lt prodname gt is the ASN 1 production name For example consider one type definition within the employee asn ASN 1 specification Employee DEFINITIONS BEGIN ans Name APPLICATION 1 IMPLICIT SEQUENCE
350. s the specification of a C or C source c or cpp file to which generated test functions will be written Test functions are used to populate an instance of a generated PDU type variable with random test data This instance can then be used in an encode function call to test the encoder Another advantage of these functions is that they can act as templates for writing your own population functions The lt filename gt argument to this option is op tional If not specified the functions will be written to lt modulename gt Test c where lt modu lename gt is the name of the module from the ASN 1 source file hdrGuardPrefix lt prefix gt This option allows the specification of a prefix that will be used in the generated defines that are added to header files to make sure they are only included once hfile lt filename gt This option allows the specification of a header h file to which all of the generated typedefs and function prototypes will be written If not specified the default is lt modulename gt h where lt modulename gt is the name of the module from the ASN 1 source file html None This option instructs the compiler to generat ed HTML markup for every compiled ASN 1 12 Running ASNIC from the Command line Option Argument Description file This markup contains hyperlinks to all ref erenced items within the specifications One HTML file is
351. s used for SEQUENCE OF SET OF constructs only It is used to pass the index of the item in the array This argument is set to 1 for all other constructs There is one contents method for passing each of the ASN 1 data types Some methods are used to handle several different types For example the charValue method is used for values of all of the different character string types A5String NumericString PrintableString etc as well as for big integer values Note that this method is overloaded The second implementation is for 16 bit character strings These strings are represented as an array of unsigned short integers in ASNIC All of the other contents methods correspond to a single equivalent ASN 1 primitive type The error handler base class has a single virtual method that must be implemented This is the error method and this has the following signature virtual int error OSCTXT pCtxt ASNICCB pCCB int stat 0 In this definition pCtxt is a pointer to the standard ASN 1 context block that should already be familiar The pCCB structure is known as a Context Control Block This can be thought of as a sub context used to control the parsing of nested constructed types within a message It is included as a parameter to the error method mainly to allow access to the seqx field This is the sequence element index used when parsing a SEQUENCE construct If parsing a particular element is to be retried this item must be decre
352. setPrefix gt objectsetPrefix gt lt prefix text This is used to specify a prefix that will be ap plied to all generated items in a module derived from an ASN 1 Information Object Set defini tion lt noPDU gt lt intCType gt n a byte intl6 uintl6 int32 uint32 int64 string Indicates that this module contains no PDU defi nitions This is normally true in modules that are imported to get common type definitions for ex ample InformationFramework This will pre vent the C version of the compiler from gen erating any control class definitions for the types in the module This is used to specify a specific C integer type be used for all unconstrained integer types By default ASN1C will use the int32 32 bit inte ger type for all unconstrained integers lt arcCType gt int32 int64 The is used to specify a specific C integer type be used for the arc types in Object Identifier def initions By default int32 32 bit integer arc val ues are generated lt namespace gt namespace gt lt namespace URI This is used to specify the target namespace for the given module when generating XSD and or XML code By default the compiler will not in clude a targetNamespace directive in the gener ated XSD code i e all items will not be assigned to any namespace This option only has mean ing when used with the xml xsd command line options lt hFile gt lt hFile gt
353. sgData msgData name givenName SMITH step 3 instantiate an instance of the ASN1C_ lt ProdName gt class to associate th ncode buffer and message data ASN1C_PersonnelRecord employ encodeBuffer msgData steps 4 and 5 encode and check return status if stat employee Encod 0 printf encoded XML message n printf const char msgbuf 232 Generated XML Decode Functions printf n step 6 get start of message pointer and message length start of message pointer is start of msgbuf call getMsgLen to get message length msgptr encodeBuffer getMsgPtr will return amp msgbuf len encodeBuffer getMsgLen else printf Encoding failed n encodeBuffer printErroriInfo exit 0 msgptr and len now describe fully encoded messag Generated XML Decode Functions A major difference between generated XER decode functions and generated XML decode functions in ASNIC version 6 0 and later is that the XML functions no longer use the Simple API for XML SAX interface Instead the XML runtime now uses an XML pull parser developed in house for improved efficiency The pull parser also provides a similar interface to that of binary encoding rules such as BER or PER meaning easier integration with existing encoding rules Finally the pull parser interface does not require integration with any 3rd party XML parser sof
354. sgbuf 1024 int msglen ASNIBEREncodeBuffer encodeBuffer msgbuf sizeof msgbuf 156 Generated BER Streaming Encode Functions ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ encodeBuffer msgData Encode loop starts here this will repeatedly use th objects declared above to encode the messages for 77 logic here to read record from some source database flat file socket etc populate structure with data to sbe encoded msgData name SMITH invoke Encode method if msglen employee Encode gt 0 encoding successful get pointer to start of message smsgptr encodeBuffer getMsgPtr do something with th ncoded messag else error processing Call the init method on th ncodeBuffer object to prepare the buffer for encoding another message encodeBuffer init Generated BER Streaming Encode Functions BER messages can be encoded directly to an output stream such as a file network or memory stream The ASN1C compiler has the stream option to generate encode functions of this type For each ASN 1 production defined in the ASN 1 source file a C stream encode function is generated This function will encode a populated C variable of the given type into an encoded ASN 1 message and write it to a stream If the return status indicates success 0 the message will have bee
355. so possible to encode a PER message to a stream rather than a memory buffer To do this you would first declare a variable of one of the OSRT output stream classes This would then be associated with the encode buffer through the ASN1PERencode buffer declaration Everything after that would be similar to the memory buffer based program The preceding program fragment rewritten to do streaming output to a file would look like this include employee h include file generated by ASNI1C main int stat OSBOOL aligned TRUE const char filename message_out per Create an instance of the compiler generated class This example write output to a file stream OSRTFileOutputStream fostrm filename ASNIPEREncodeBuffer encodeBuffer fostrm aligned ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ encodeBuffer msgData Populate msgData within the class variable msgData name givenName SMITH Encode if stat employee Encod 0 printf Encoding was successful n printf Hex dump of encoded record n ncodeBuffer hexDump printf Binary dump n encodeBuffer binDump employee else printf Encoding failed n encodeBuffer printErroriInfo 193 Encoding a Series of PER Mes sages using the C Interface exit 0 return 0 Note that the encodeBuffer hexDump and encodeBuffer binDu
356. source files for a given ASN 1 module note the name of the module would be substituted for lt moduleName gt lt moduleName gt c common definitions and functions for example asnlFree_ lt type gt and or global value constant definitions lt moduleName gt Enc c encode functions asnlE_ lt type gt lt moduleName gt Dec c decode functions asn1 D_ lt type gt If additional options are used such as genPrint genCopy etc additional files will be generated lt moduleName gt Copy c copy functions generated if genCopy is speci fied lt moduleName gt Print c print functions generated if genPrint is speci fied lt moduleName gt Compare c comparison functions generated if genCom pare is specified 114 Maximum Lines per File lt moduleName gt PrtToStr c print to string functions generated if genPrt ToStr is specified lt moduleName gt PrtToStrm c print to stream functions generated if genPrt ToStrm is specified lt moduleName gt Table c table constraint functions generated if gen Table option is specified lt moduleName gt Test c test functions generated if genTest is specified If genCopy genPrint etc have a filename parameter then the code will be written to the given file instead of the default one If the cfile lt filename gt option is used and genCopy genPrint etc op tions do not have
357. static command line option If this is done the elements within the union construct will be standard inline variable declarations and can be populated directly Otherwise the methods listed below can be used to populate the variables The recommended way to populate the pointer elements is to declare variables of the embedded type to be used on the stack prior to populating the CHOICE structure The embedded variable would then be populated with the data to be encoded and then the address of this variable would be plugged into the CHOICE union pointer field Consider the following definitions AsciiString PRIVATE 28 OCTET STRING EBCDICString PRIVATE 29 OCTET STRING String CHOICE AsciiString EBCDICString This would result in the following type definitions typedef OSDynOctStr AsciiString typedef OSDynOctStr EBCDICString typedef struct String Ene GP union ROE Sd ey AsciiString asciiString SE ee Re ee EBCDICString eBCDICString u String To set the AsciiString choice value one would first declare an AsciiString variable populate it and then plug the address into a variable of type String structure as follows AsciiString asciiString String string asciiString Hello string t T_String_AsciiString string u asciiString amp asciiString 68 Open Type It is also possible to allocate dynamic memory for the CHOICE union option variable but
358. step further it ties the type of the field to the type specified in the row that matches the given opcode value An example of the information object set and corresponding information objects would be as fol lows My ops OPERATION makeCall fwdCall makeCall OPERATION ArgumentType MakeCallArgument amp 0perationCode local 10 fwdCall OPERATION amp ArgumentType FwdCallArgument amp 0perationCode local 11 The C or C type generated for the SEQUENCE above when table unions is specified would be as follows typedef struct EXTERN Invoke OSINT32 invokeID _OPERATION_operationCode opcode struct information object selector ad My_ops_TVALUE t My_ops information objects xf union operationCode local 10 MakeCallArgument makeCall operationCode local 11 FwdCallArgument fwdCall ASN1OpenType extEleml1 u argument Invoke Each of the options from the information object set are enumerated in the union structure All a user needs to do to encode a variable of this type is to set the t value in the structure to the selected information object field and then populate the type field This is very similar to populating a CHOICE construct The comments in the elements show what the value of the key element s must be if that alternative is selected The open type field at the end extElem1
359. string not to be confused with null then no element name is applied to the encoded data The function result variable stat returns the status of the encode operation Status code zero indi cates the function was successful A negative value indicates encoding failed Return status values are defined in the rtxErrCodes h include file The error text and a stack trace can be displayed using the rtxErrPrint function Generated C Encode Method Format and Calling Parameters Generated encode functions are invoked through the class interface by calling the base class Encode method The calling sequence for this method is as follows stat lt object gt Encode In this definition lt object gt is an object of the class generated for the given production The function result variable stat returns the status value from the XER encode function This status value will be zero if encoding was successful or a negative error status value if encoding fails Return status values are defined in the rtxErrCodes h include file The user must call the encode buffer class methods getMsgPtr and getMsgLen to obtain the starting address and length of the encoded message component Procedure for Calling C Encode Functions This section describes the step by step procedure for calling C XER encode functions This pro cedure is similar to that for the other encoding methods except that some of the functions used are specific to XER Before an XER
360. structured type is declared The programmer therefore does not have to be worried about clearing bits for elements that are not used only with setting bits for the elements that are to be encoded 58 SEQUENCE DEFAULT keyword The DEFAULT keyword allows a default value to be specified for elements within the SE QUENCE ASNIC will parse this specification and treat it as it does an optional element Note that the value specification is only parsed in simple cases for primitive values It is up to the pro grammer to provide the value in complex cases For BER encoding a value must be specified be it the default or other value For DER or PER it is a requirement that no value be present in the encoding for the default value For integer and boolean default values the compiler automatically generates code to handle this requirement based on the value in the structure For other values an optional present flag bit is generated The programmer must set this bit to false on the encode side to specify default value selected If this is done a value is not encoded into the message On the decode side the developer must test for present bit not set If this is the case the default value specified in the ASN 1 speci fication must be used and the value in the structure ignored Extension Elements If the SEQUENCE type contains an open extension field 1 e a at the end of the specification or a in the middle a special element w
361. successful a pointer to the encoded message can be obtained by using the getMsgPtr or getMsgCopy methods available in the ASN BEREncodeBuffer class The getMsgPtr method is faster as it simply returns a pointer to the actual start of message that is maintained within the message buffer object The getMsgCopy method will return a copy of the message Memory for this copy will be allocated using the standard new operator so it is up to the user to free this memory using delete when finished with the copy A program fragment that could be used to encode an employee record is as follows This example uses a static encode buffer include employee h include file generated by ASNIC main const OSOCTET msgptr OSOCTET msgbuf 1024 int msglen step 1 construct ASNIC C generated class this specifies a static encode message buffer ASNIBEREncodeBuffer encodeBuffer msgbuf sizeof msgbuf ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ encodeBuffer msgData step 2 populate msgData structure with data to be encoded msgData name SMITH step 3 invoke Encode method if msglen employee Encode gt 0 encoding successful get pointer to start of message msgptr encodeBuffer getMsgPtr else error processing 155 Generated C Encode Method Format and Calling Parameters The following code fragment illustrates
362. t This option instructs the compiler to generate a Visual Studio compatible makefile It is equiva lent to using the genMake w32 combination of command line options noContaining nodecode None None This option suppresses the generation of in line code to support the CONTAINING key word Instead a normal OCTET STRING or BIT STRING type is inserted as was done in pre vious ASNIC versions This option suppresses the generation of decode functions noencode None This option suppresses the generation of encode functions noIndefLen This option instructs the compiler to omit indef inite length tests in generated decode functions These tests result in the generation of a large amount of code If you know that your applica tion only uses definite length encoding this op tion can result in a much smaller code base size noInit None This option instructs the compiler to not gener ate an initialization function for each ASN 1 pro 14 Running ASNIC from the Command line Option Argument Description duction A variable of a generated structure can always be initialized by memset ing the variable to zero However this is not usually the most ef ficient way to initialize a variable because if it contains large byte arrays a significant amount of processing is required to set all bytes to zero and they don t need to be Initialization func tion
363. t amp getCopy ASN1T_ lt name gt pDstData 0 For example ASN1T_PersonnelRecord amp getCopy ASN1T_PersonnelRecord pDstData 0 The pDstData argument is used to pass the pointer to a destination variable where the value will be copied It may be null in this case the new ASN1IT_ lt name gt variable will be allocated via a call to the rtxMemAlloc function A newCopy method that will create a new dynamically allocated copy of the referenced ASNIT_ data member variable An assignment operator This is used to copy one instance of a control class to another one inline ASN1C_ lt name gt amp operator ASN1C_ lt name gt amp srcData srcData getCopy amp msgData return this For example inline ASN1C_PersonnelRecord operator ASN1C_PersonnelRecord amp srcData srcData getCopy amp msgData return this Finally the class declaration might look as follows class EXTERN ASN1C_PersonnelRecord 246 Generated Copy Functions public ASN1CType protected ASN1T_PersonnelRecord msgData public ASN1C_PersonnelRecord ASN1MessageBuffer amp msgBuf ASN1T_PersonnelRecord amp data ASN1C_PersonnelRecord ASN1C_PersonnelRecord amp original ASN1T_PersonnelRecord amp getCopy ASN1T_PersonnelRecord pDstData 0 ASN1T_PersonnelRecord newCopy inline ASN1C_PersonnelRecord amp operator ASN1C_PersonnelRecord amp srcData srcData getCopy amp
364. t be dealt with There are three alternatives for managing memory for these types 1 Allocate the variables on the stack and plug the address of the variables into the pointer fields 2 Use the standard malloc and free C functions or new and delete C operators to allocate mem ory to hold the data and 3 Use the rxtMemAlloc and rtxMemFree run time library functions or their associated macros Allocating the variables on the stack is an easy way to get temporary memory and have it released when it is no longer being used But one has to be careful when using additional functions to populate these types of variables A common mistake is the storage of the addresses of automatic variables in the pointer fields of a passed in structure An example of this error is as follows assume A B and C are other structured types typedef struct A a B b CEE Parent void fillParent Parent parent A aa B bb Cs ec 145 Accessing Encoded Message Components logic to populate aa bb and cc parent gt a amp aa parent gt b amp bb parent gt c cc main Parent parent fillParent amp parent encodeParent amp parent error pointers in parent reference memory that is out of scope In this example the automatic variables aa bb and cc go out of scope when the fi Parent function exits Yet the parent structure is still holding pointers to the now out of scope var
365. t msglen OSCTXT CUxXt Employee employee typedef generated by ASNIC Step 1 Initialize the context and set the buffer pointer if rtInitContext amp ctxt 0 initialization failed could be a license problem printf context initialization failed check license n return 1 xe_setp amp ctxt msgbuf sizeof msgbuf Step 2 Populate the structure to b ncoded mployee name givenName SMITH Step 3 Call the generated encode function msglen asnlE_Employee amp ctxt amp employee ASN1EXPL Step 4 Check the return status note the test is gt 0 because the returned value is the length of the encoded message component if msglen gt 0 151 Generated C Function For mat and Calling Parameters Step 5 If encoding is successful call xe_getp to fetch a pointer to the start of th ncoded message msgptr xe_getp amp ctxt else TUXErrPrint ctxt return msglen In general static buffers should be used for encoding messages where possible as they offer a substantial performance benefit over dynamic buffer allocation The problem with static buffers however is that you are required to estimate in advance the approximate size of the messages you will be encoding There is no built in formula to do this the size of an ASN 1 message can vary widely based on data types and the number
366. t typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each generated print function is as follows asnlPrint_ lt name gt const char name lt name gt pvalue In this definition lt name gt denotes the prefixed production name defined above The name argument is used to hold the top level name of the variable being printed It is typically set to the same name as the pvalue argument in quotes for example to print an employee record a call to asnIPrint_Employee employee amp employee might be used The pvalue argument is used to pass a pointer to a variable of the item to be printed If C code generation is specified a Print method is added to the ASNIC control class for the type This method takes only a name argument the pvalue argument is obtained from the msgData reference contained within the class Print to String The genPrtToStr option causes functions to be generated that print the contents of variables of generated types to a given text buffer This buffer can then be used to output the information to other mediums such as a file or window display It is possible to specify the name of a c or cpp file as an argument to this option to specify the name of the file to which these functions will be written This is an optional argument If not specified the functions are written to separate file
367. t variable This status is returned by the decoder when a target variable is not large enough to hold a a decoded value A typical case is an integer value that is too large to fit in the standard C integer type typically a 32 bit value on a given platform If this occurs it is usually necessary to use a configuration file setting to force the compiler to use a different data type for the item For example for integer the lt isBigInteger gt setting can be used to force use of a big integer type 24 RTERR_INVCHAR Invalid character This status code is returned when a character is encountered that is not valid for a given data type For example if an integer value is being decoded and a non numeric char acter is encountered this error will be raised 25 RTERR_XMLSTATE XML state error This status code is returned when the XML parser 26 RTERR_XMLPARSE XML parser error This status code in returned when the underlying XML parser application by default this is Expat returns an error code The parser error code or text is returned as a pa rameter in is not in the correct state to do a cer tain operation 27 RTERR_SEQORDER Sequence order error This status code is re turned when decoding an ASN 1 SEQUENCE or XSD xsd sequence construct It is raised if the elements were received in an order different than that specified the errInfo structure within the context structure 273
368. ta opcode subid 2 1 note opcode value is 0 1 1 so argument must be ASN1VisibleString type ASN1VisibleString argument objsys msgData argument decoded void amp argument Step 4 Call the generated encode function msglen asnlE_Invoke amp ctxt amp invoke ASN1EXPL Step 5 Check the return status note the test is gt 0 because the returned value is the length of the encoded message component if msglen gt 0 Step 6 If encoding is successful call xe_getp to fetch a pointer to the start of th ncoded message msgptr xe_getp amp ctxt else error processing General Procedure for Table Constraint Decod ing The general procedure to decode an ASN 1 message with table constraints is the same as without table constraints The only difference will exist in the decoded data for open type fields within the message In this case the Asn Object AsnITObject s decoded member variable will contain the original decoded type and the encoded member variable will contain the original data in encoded form Refer to the BER DER PER decoding procedure for further information The procedure to retrieve the value for open type fields is as follow 1 Check the possible Type in the Information Object Set from index element value 2 Assign or cast the Asn Object decoded member variable void to the result type 3 The Asn Object
369. ta to be encoded Instantiate an ASN1C_ lt type gt object to associate the message buffer with the data to be encod ed Invoke the ASN1C_ lt type gt object Encode or EncodeTo method Check the return status The return value is a status value indicating whether encoding was successful or not Zero indicates success If encoding failed the status value will be a negative number The encode buffer method printErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred If encoding was successful get the start of message pointer and message length The start of message pointer is obtained by calling the getMsgPtr method of the encode buffer object If static encoding was specified i e a message buffer address and size were specified to the XML Encode Buffer class constructor the start of message pointer is the buffer start address The message length is obtained by calling the getMsgLen method of the encode buffer object A program fragment that could be used to encode an employee record is as follows include employee h include file generated by ASNI1C main OSOCTET msgbuf 4096 int msglen stat step 1 instantiate an instance of the XML encod buffer class This example specifies a static message buffer OSXMLEncodeBuffer encodeBuffer msgbuf sizeof msgbuf step 2 populate msgData with data to be encoded ASN1T_PersonnelRecord m
370. tbersrc ASNIBERDecodeStream h include rtxsrc OSRTFileInputStream h main ASNITAG tag int i len const char filename message dat OSBOOL trace TRUE Decode ASNIBERDecodeStream in new OSRTFileInputStream filename if in getStatus 0 in printErrorInfo return 1 if in peekTagAndLen tag len 0 printf peekTagAndLen failed n in printErrorInfo return 1 Now switch on initial tag value to determine what 183 Generated Streaming C Decode Method Format and Calling Parameters type of message was received switch msgtag case TV_PersonnelRecord compiler generated constant ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ msgData in gt gt employee if in getStatus 0 printf decode of PersonnelRecord failed n in printErrorInfo return i or employee DecodeFrom in break case TV_ handle other known messages return 0 Note that the call to free memory and the stream close method are not required to release dynamic memory when using the C interface This is because the control class hides all of the details of managing the context and releasing dynamic memory The memory is automatically released when both the input stream object ASN BERDecodeStream and derived classes and the control class object ASNJC_ lt ProdName gt
371. ter and length of encoded Login ARGUMENT A Encoded ROSE message ROSE Layer 263 SNMP OBJECT TYPE The login OPERATION also contains references to ERROR definitions These are defined using a separate MACRO that is built into the compiler The definition of this MACRO is as follows ERROR MACRO BEGIN TYPE NOTATION Parameter VALUE NOTATION value VALUE INTEGER Parameter PARAMETER NamedType empty NamedType identifier type typ END In this definition an error is assigned an identifying number as well as on optional parameter type to hold parameters associated with the error An example of a reference to this MACRO for the authent icationFailure error in the login operation defined earlier would be as follows applicationError ERROR PARAMETER SEQUENCE errorText IA5String The ASNIC compiler will generate a type definition for the error parameter and a value constant for the error value The format of the name of the type generated will be lt name gt _PARAMETER where lt name gt is the ERROR name applicationError in this case with the first letter set to upper case The name of the value will simply be the ERROR name SNMP OBJECT TYPE The SNMP OBJECT TYPE MACRO is one of several MACROs used in Management Information Base MIB definitions It is the only MACRO of interest to ASNIC because it is the one that specifi
372. th the generated code strict None This option instructs the compiler to generate code for strict validation of table constraints By default generated code will not check for value field constraints It should be noted that real world messages typi cally do not strictly follow value field table con straint definitions Therefore this option should be used with care syntaxcheck None This option instructs the compiler to do a syntax check of the ASN 1 source files only No code is to be generated table unions None This option instructs the compiler to generate union structures for table constraints in C C instead of void pointers as is done when the ta bles option is used These are generally easier to use as they present all options in a user friendly way targetns lt namespace gt This option only has meaning when generating an XML schema definitions XSD file using the xsd option It allows specification of a target namespace lt namespace gt is a namespace URI if it is not provided no target namespace declaration is added to the generated XSD file trace None This option is used to tell the compiler to add trace diagnostic messages to the generated code These messages cause print statements to be added to the generated code to print entry and ex it information into the generated functions This is a debugging option that allows encode decode problems to
373. the ASN 1 module name for this class definition C Code generation The C structure definition generated to model an ASN 1 class contains member variables for each of the fields within the class 88 Legacy Table Constraint Model For each of the following class fields the corresponding member variable is included in the gen erated C structure as follows For a Value Field lt TypeName gt lt FieldName gt For TypeField definitions an encode and decode function pointer and type size field is generated to hold the information of the type for the OpenType If the print option is selected a print function pointer is also added int lt FieldName gt Size int encode lt FieldName gt int decode lt FieldName gt 7 void print lt FieldName gt For an Object Field lt ClassName gt lt FieldName gt For an ObjectSetField definition an array of class definitions is generated to hold the list of infor mation objects lt ClassName gt lt FieldName gt In each of these definitions lt FieldName gt would be replaced with the name of the field without the leading amp lt TypeName gt would be replaced with the C type name for the ASN 1 Type lt ClassName gt would be replaced with the C type name of the class for the Information Object As an example consider the following ASN 1 class definition ATTRIBUTE CLASS amp Type amp id
374. the block is static declared on the stack and initialized using rtInitContext or dynamic created using rtNewContext The function to free the context is rtFreeContext A program fragment that could be used to decode an employee record is as follows include employee h include file generated by ASNIC main OSOCTET pMsgBuf int len stat 205 Procedure for Calling C Decode Functions OSCTXT ctxt PersonnelRecord employee const char filename message dat step 1 initialize context stat rtInitContext amp ctxt if stat 0 printf rtInitContext failed check license n rtErrPrint amp ctxt return stat step 2 read input file into a memory buffer stat rtxFileReadBinary amp ctxt filename amp pMsgBuf amp len if 0 stat stat rtxInitContextBuffer amp ctxt pMsgBuf len if 0 stat rtxErrPrint amp ctxt rtFreeContext amp ctxt return stat step 3 initialize the data variable asnlInit_PersonnelRecord amp employee step 4 call the decode function stat OERDec_PersonnelRecord amp ctxt amp employee if stat 0 process received data else error processing rtxErrPrint amp ctxt step 4 free the context rtFreeContext amp ctxt An input stream can be used instead of a memory buffer as the data source by replacing the rt
375. time function is called with a fixed sixed static buffer and whatever op eration is being done causes the bounds of this buffer to be exceeded 271 General Status Messages Error Code Error Name Description 14 15 RTERR_BADVALUE RTERR_TOODEEP Bad value This status code is returned anywhere where an API is expecting a value to be within a certain range and it not within this range An example is the encoding or decoding date values when the month or day value is not within the legal range 1 12 for month and 1 to whatever the max days is for a given month Nesting level too deep This status code is re turned when a preconfigured maximum nesting level for elements within a content model group is exceeded 16 RTERR_CONSVIO Constraint violation This status code is returned when constraints defined the schema are vio lated These include XSD facets such as min maxOccurs minmaxLength patterns etc Also ASN 1 value range size and permitted alphabet constraints 17 RTERR_ENDOFFILE Unexpected end of file error This status code is returned when an unexpected end of file condi tion is detected on decode It is similar to the ENDOFBUEF error code described above except that in this case decoding is being done from a file stream instead of from a memory buffer 18 19 RTERR_INVUTF8 RTERR_OUTOFBND Invalid UTF 8 character encoding This status code is retur
376. to build static library make lt filename gt same as genMake as described abov Running ASNIC from the Command line nmake lt filename gt generate Windows nmake fil same as genMak w32 vcproj version generate Visual Studio project files version is 2008 2005 2003 Windows only builddll generate makefile project to build DLL dll usedlil generate makefile project to use DLL s mt generate makefile project to use multithreaded libs w32 generate code for Windows 32 bit O S default GNU w64 generate code for Windows 64 bit O S default GNU Java options compare generate comparison functions dirs output Java code to module name dirs genbuild generate build script genant generate ant build xml script genjsources generate lt modulename gt mk for list of java files getset generate get set methods and protected member vars pkgname lt text gt pkgpfx lt text gt java4 C options nspfx lt text gt Java package name Java package prefix genera te code for Java 1 4 C namespace prefix namespace lt text gt C namespace name dirs output C code to module name dirs csfile lt filename gt generate one cs file or one per module cs gencssources generate lt modulename gt mk for list of C files genMake generate makefile to build generated code pro options events generate code to invoke SAX
377. tructed type consisting of a series of element definitions These elements can be of any ASN 1 type including other constructed types For example it is possible to nest a SEQUENCE definition within another SEQUENCE definition as follows A SEQUENCE x SEQUENCE al INTEGER a2 BOOLEAN Fy y OCTET STRING SIZE 10 In this example the production has two elements x and y The nested SEQUENCE x has two additional elements a1 and a2 The ASN1C compiler first recursively pulls all of the embedded constructed elements out of the SE QUENCE and forms new internal types The names of these types are of the form lt name gt _ lt element namel gt _ lt elementname2 gt _ lt element nameN gt For example in the definition above two tempo rary types would be generated a_x and a_y a_yis generated because a static OCTET STRING maps to a C struct type The general form is as follows ASN 1 production lt name gt SEQUENCE lt elementil name gt lt elementl type gt lt element2 name gt lt element2 type gt Generated C code typedef struct lt typel gt lt element1 name gt lt type2 gt lt element2 nam Vv SaaneSi or typedef struct SrenpNan is typedef struct 55 SEQUENCE lt tempName2 gt typedef struct lt tempNamel gt lt elementl name gt lt tempName2 gt lt
378. tructure This structure uses a void pointer to hold a link to a variable of the typed data structure This is inconvenient for the developer because he would need to consult the object set definition within the ASN 1 specification in order to determine what type of data is to be used with each procedure code It is also error prone in that the void pointer provides for no type checking at compile time In the new model the generated structure is designed to be similar as to what is used to represent a CHOICE type That is to say the structure is a union with a choice selector value and all possible types listed out in a union structure This is the general form typedef struct lt Type gt lt ElementiType gt lt element1 gt lt Element2Type gt lt element2 gt information object selector x lt SelectorEnumType gt t lt ObjectSet gt information objects union lt element1 gt lt objectl element1l value gt lt element2 gt lt objectl element2 value gt lt object1l element3 type gt lt object1l name gt 82 Unions Table Constraint Model lt element1 gt lt object2 element1 value gt lt element2 gt lt object2 element2 value gt lt object2 element3 type gt lt object2 name gt In this definition the first two elements of the sequence would use the equivalent C or C type as defined in the fixed type field in the information
379. tting used to set the prefix is the lt typeprefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each generated copy function is as follows void asnliCopy_ lt name gt OSCTXT pctxt lt name gt pSrcValue lt name gt pDstValue In this definition lt name gt denotes the prefixed production name defined above The pointer to the context structure pctxt provides a storage area for the function to store all variables that have been copied 245 Generated Copy Functions The pSrcValue argument is used to pass a pointer to a variable to be copied The pDstValue argu ment is used to pass the pointer to the destination value The source value is then copied to the destination value field by field Memory will be allocated for dynamic fields using calls to the rtxMemAlloc function If C is used cpp option is specified and PDU generation is not disabled lt noPDU gt config option is not used then the control class ASN1C_ lt name gt additionally will contain e A copy constructor that can be used to create an exact copy of the class instance The calling sequence is as follows ASN1C_ lt name gt ASN1C_ lt name gt amp orginal For example ASN1C_PersonnelRecord ASN1C_PersonnelRecord amp original A getCopy method that creates a copy of the ASN T_ lt name gt variable ASN1T_ lt name g
380. ttribute list lt storage gt lt storage gt dynamic static list ar ray or dynamicArray keyword This item allows a list of ASN 1 types and or values to be excluded in the generated code By default the compiler generates code for all types and values within a specification This is gener ally not as useful as in include directive because most types in a specification are referenced by other types If an attempt is made to exclude a type or value referenced by another item the di rective will be ignored The definition is the same as for the global case except that the specified storage type will only be applied to generated C and C types from the given module lt sourceFile gt lt source source file name File gt Indicates the given module is contained within the given ASN 1 source file This is used on IM PORTS to instruct the compiler where to look for imported definitions lt prefix gt lt prefix gt prefix text This is used to specify a general prefix that will be applied to all generated C and C names note for C types the prefix is applied after the standard ASN1T_ prefix This can be used to prevent name clashes if multiple modules are involved in a compilation and they all contain common names lt typePrefix gt lt type prefix text Prefix gt lt enumPrefix gt enumPrefix gt lt prefix text This is used to specify a prefix that will be ap plie
381. tware XML decode functions are generated when the xml switch is specified on the command line For each ASN 1 production defined in the ASN 1 source file a C XML decode function is generated This function will parse the data contents from an XML message of the corresponding ASN 1 or XML schema type and populate a variable of the C type with the data If C code generation is specified a control class is generated that contains a DecodeFrom method that wraps this function This function is invoked through the class interface to encode an ASN 1 message into the variable referenced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each generated XML decode function is as follows lt namespace gt XmlDec_ lt prefix gt lt prodName gt where lt namespace gt is an optional C namespace prefix lt prodName gt is the name of the ASN 1 pro duction for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePre fix gt element This element specifies a prefix that will be applied to all generated typedef names 233 Procedure for Calling C Decode Functions and function names for the production lt namespace gt is set using the ASNIC namespace com mand line argument Note that this should not be confused with the notion of
382. ty OperationList Operation OperationList Operation Operation value OPERATION shall reference an op value type shall reference an op type if no value is specified NamedType identifier type typ END This MACRO does not need to be defined in the ASN 1 specification to be parsed In fact any attempt to redefine this MACRO will be ignored Its definition is hard coded into the compiler The compiler uses this definition to parse types and values out of OPERATION definitions An example of an OPERATION definition is as follows 261 ROSE OPERATION and ERROR login OPERATION ARGUMENT SEQUENCE username IA5String password IA5String RESULT SEQUENCE ticket OCTET STRING welcomeMessage IA5String ERRORS authenticationFailure insufficientResources 1 In this case there are two embedded types an ARGUMENT type and a RESULT type and an integer value 1 that identifies the OPERATION There are also error definitions The ASNIC compiler generates two types of items for the OPERATION 1 It extracts the type definitions from within the OPERATION definitions and generates equiva lent C C structures and encoders decoders and 2 It generates value constants for the value associated with the OPERATION i e the value to the right of the in the definition The compiler does not generate any structures or code related to the OPERATION itself for e
383. typedef struct EXTERN NamePart_choice int ES 104 xsd any Attribute union EOC Ls 87 const OSUTF8CHAR givenName PRP te ple a const OSUTF8CHAR initial EOE BRL const OSUTF8CHAR familyName u NamePart_choice typedef struct EXTERN NamePart struct unsigned occupationPresent 1 m const OSUTF8CHAR occupation NamePart_choice choice NamePart In this case occupation attribute declaration was added as before But the choice group became a separate embedded element called choice which the ASN1C compiler pulled out to create the NamePart_choice temporary type This type was then referenced by the choice element in the gen erated type definition for NamePart xsd anyAttribute An xsd anyAttribute declaration is the attribute equivalent to the xsd any wildcard element decla ration described earlier The main difference is that a single xsd anyAttribute declaration indicates that any number of undeclared attributes may occur whereas xsd any without a maxOccurs facet indicates that only a single wildcard element may occur at that position X 694 models xsd anyAttribute as a SEQUENCE OF UTFSString in ASN 1 Each string in the sequence is expected to be in a name value format The generated C type for this is simply a linked list of character strings For example lt xsd complexType name MyType gt lt xsd anyAttribute processContents lax gt lt xsd complexType gt r
384. uct OSUINT32 n lt type gt elem lt len gt lt name gt Generated C code typedef struct OSUINT32 n lt type gt elem lt len gt ASN1T_ lt name gt List based SEQUENCE OF Type A doubly linked list header type OSRTDList is used for the type definition if the list storage configuration setting is used see above This can be used for either a sized or unsized SEQUENCE OF construct The generated C or C code is as follows Generated C code 62 SEQUENCE OF typedef OSRTDList lt name gt Generated C code typedef ASN1TSeqOfList ASN1IT_ lt name gt The type definition of the OSRTDList structure can be found in the osSysTypes h header file The common run time utility functions beginning with the prefix rtxDList are available for initializing and adding elements to the list See the C C Common Run time Reference Manual for a full description of these functions For C the ASN TSeqOfList class is used or in the case of PDU types the ASV TPDUSeqOfList class The ASNITSeqOfList extends the C OSRTDList structure and adds constructors and other helper methods The ASNJTPDUSeqOjList is similar except that it also extends the ASN TPDU base class to add additional memory management capabilities needed by PDU types to automat ically release memory on destruction See the ASN CSeqOfList section in the C C Common Run time Reference Manual for details on all of the methods available in this class
385. ue as in the other cases It also has an element name argument elemName that contains the name of the element to be encoded and an attributes argument attributes that can be used to encode an attributes string The decode function is generated for PDU types only decoding of internally referenced types is accomplished through generated SAX handler callback functions which are invoked by an XML parser If XML functions are generated using the xml switch the function prototypes are as follows int XmlEnc_ lt ProdName gt OSCTXT pctxt lt ProdName gt value const OSUTF8CHAR elemName const OSUTF8CHAR nsPrefix int XmlDec_ lt ProdName gt OSCTXT pctxt lt ProdName gt pvalue In this case the encode function contains an argument for XML element name elemName and also namespace prefix nsPrefix Generated C Control Class Definition A control class definition is generated for each defined production in the ASN 1 source file that is determined to be a Protocol Data Unit PDU By default any type defined in an ASN 1 source file that is not referenced by any other type is a PDU This default behavior can be overridden by using a configuration file setting lt isPDU gt or a command line option pdu to explicitly declare that certain types are PDU s The generated control class is derived from the ASN CType base class This class provides a set of common attributes and methods for encoding decoding ASN 1
386. ugh the context This makes it possible to provide an implementation of the rtxMemHeapFreeAll function as described above This memory management scheme is slower than the default manager i e nibble based but has a smaller code footprint This form of memory management is enabled by defining the MEMCOMPACT C compile time setting This can be done by either adding D_MEMCOMPACT to the C compiler command line arguments or by uncommenting this item at the beginning of the rtxMemory h header file Uncomment this definition before building the C or C run time libraries to enable compact memory management This will have a smaller code footprint than the standard memory management however the performance may not be as good define _MEMCOMPACT Low Level Memory Management API 142 Dynamic Memory Management It is possible to replace the core memory management functions used by the ASNIC run time memory manager This has the advantage of preserving the existing management scheme but with the use of different core functions Using different core functions may be necessary on some sys tems that do not have the standard C run time functions malloc free and realloc or when extra functionality is desired To replace the core functions the following run time library function would be used void rtxMemSetAllocFuncs OSMallocFunc malloc_func OSReallocFunc realloc_func OSFreeFunc free_func The malloc rea
387. unctions generated if genCopy is speci fied lt moduleName gt Print cpp print functions generated if genPrint is speci fied lt moduleName gt Compare cpp comparison functions generated if genCom pare is specified lt moduleName gt PrtToStr cpp print to string functions generated if genPrt ToStr is specified lt moduleName gt PrtToStrm cpp print to stream functions generated if genPrt ToStrm is specified lt moduleName gt Table cpp table constraint functions generated if gen Table option is specified lt moduleName gt Test cpp test functions generated if genTest is specified The maxcfiles option for C works very similar to how it works for C The only differences are a few additional files are generated and the cpp extension is used instead of c Additional files are generated to hold ASNIC_ lt Type gt and ASNIT_ lt Type gt control classes The format of the filenames of these files is as follows asnl lt suffix gt _ lt prodname gt cpp ASN1C_ lt prodname gt cpp ASN1T_ lt prodname gt cpp where lt suffix gt depends on the encoding rules and function type selected encode decode free etc and lt prodname gt is the ASN 1 production name For the example presented previously in the C Files section the following files would be generated for the Name production in the employee asn file asnlD_Name cpp asnlE_Name cpp ASN1T_Name cpp ASN1C_Name cpp
388. urgency ENUMERATED normal high DEFAULT normal alternate item cod INTEGER 0 254 alternate item nam TA5String SIZE 3 10 OPTIONAL 1 59 SET In this case a special bit flag will be added to the mask structure to indicate the presence or absence of the entire element block This will be of the form _v ExtPresent where would be replaced by the sequential version number In the example above this number would be three two would be the version extension number of the urgency field Therefore the generated bit mask would be as follows struct unsigned item_namePresent 1 unsigned urgencyPresent 1 unsigned _v3ExtPresent 1 unsigned alternate_item_namePresent 1 m In this case the setting of the _v3ExtPresent flag would indicate the presence or absence of the entire version block Note that it is also possible to have optional items within the block alter nate item name C Mapping of SEQUENCE The C mapping of an ASN 1 SEQUENCE type is very similar to the C mapping However there are some important differences 1 As with all C types the prefix ASN1T_ is added before the typename to distinguish the data class from the control class the control class contains an ASN1C_ prefix 2 A default constructor is generated to initialize the structure elements This constructor will ini tialize all elements and set any simple default values that may have been specif
389. utput Stream for an IP socket connection 2 Create an ASNI BEREncodeStream object using the stream object created in 1 as an argument 3 Create a variable of the ASN T_ lt name gt type and populate it with the data to be encoded 4 Create a variable of the generated ASN1C_ lt name gt class specifying the item created in 2 as an argument to the constructor 5 Invoke the EncodeTo method or lt lt operator A program fragment that could be used to encode an employee record is as follows This example uses a file output stream include employee h include file generated by ASNI1C include rtbersrc ASN1IBEREncodeStream h include rtxsrc OSRTFileOutputStream h 162 Generated Streaming C Encode Method Format and Calling Parameters main Q int msglen const char filenam ASNIBEREncodeStream out tatus 0 ErroriInfo if step 1 out getsS out print message dat construct output stream object return 1 step 2 new OSRTFileOutputStream filename construct ASN1C C generated class ASN1T_PersonnelRecord msgData ASN1C_PersonnelRecord employ msgData step 3 populate msgData structure with data to be note this uses the generated assignment operator to assign a string encoded msgData name SMITH step 4 invoke lt lt operator or out lt lt employe
390. will convert a populated C variable of the given type into a PER encoded ASN 1 message If C code generation is specified a control class is generated that contains an Encode method that wraps this function This function is invoked through the class interface to encode an ASN 1 message into the variable referenced in the msgData component of the class Generated C Function Format and Calling Pa rameters The format of the name of each generated PER encode function is as follows asnlPE_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt is an optional prefix that can be set via a configuration file setting The configuration setting used to set the prefix is the lt typePrefix gt element This element specifies a prefix that will be applied to all generated typedef names and function names for the production The calling sequence for each encode function is as follows status asnlPE_ lt name gt OSCTXT pctxt lt name gt value In this definition lt name gt denotes the prefixed production name defined above The pctxt argument is used to hold a context pointer to keep track of encode parameters This is a basic handle variable that is used to make the function reentrant so it can be used in an asynchronous or threaded application The user is required to supply a pointer to a variable of this type declared somewhere i
391. window contains options for generating makefiles and Visual Studio projects Make file and project targets may be modified by selecting Generate Libraries or Link applications using shared libraries If the latter option is checked applications will be dynamically linked instead of statically linked Compilation When all options have been specified the final screen may be used to execute the compilation command 29 Compiling and Linking Generated Code Compile Compilation Options F Generate listing ist Show compilation warnings warnings Compilation command C acv630 pin asn 1c C acv630 cpp sample_ber employee employee asn O C acv630 cpp sample_ber employee useAsn 1Xsd ber per xml xsd cpp depends ist warnings Compilation Results a Save Project TZ compile Included in the window are the compiler command an option to save the project and the output from compilation Selected options are reflected in the command line It is also possible to generate a printed listing of the input specifications Warnings encountered during compilation will also be printed if the appropriate check box is marked Click Finish to terminate the program The wizard will ask whether or not to save any changes made whether a new project has been created or not Compiling and Linking Generated Code C C source code generated by the compiler can be compiled using any ANSI standard C or C com
392. xFil eReadBinary code block above with one of the rtxStreamCreateReader functions to set up a file memory or socket stream as input 206 Generated Medical Device Encoding Rules MDER Functions Note MDER is available only as a professional compiler option The encoding and decoding functions are built on top of ASN1C s streaming functions and will not work with the typical buffer based implementations seen in BER or PER When introduced in version 6 4 no C implementation for MDER was available The Medical Device Encoding Rules MDER are described in IEEE standard 11073 20601 2008 Annex F This standard describes a simplified encoding to be used across medical devices ASN1C can generate encoders and decoders for specifications based on the IEEE standard which uses a strict subset of ASN 1 To generate encoding and decoding functions use the mder switch on the command line or select the appropriate option in the GUI The following sections describe the generated encoding and decoding functions Descriptions of the MDER run time functions may be found in our CMDER Runtime Library Reference Manual Generated MDER Encode Functions Generated C Function Format and Calling Pa rameters The format of the name of each generated encode function is as follows mderEnc_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt
393. xam ple code to encode the body and header in a single step The reason is because of the multi layered nature of the protocol It is assumed that the user of such a protocol would be most interested in doing the processing in multiple stages hence no single function or structure is generated Therefore to encode the login example the user would do the following 1 At the application layer the Login ARGUMENT structure would be populated with the user name and password to be encoded 2 The encode function for Login ARGUMENT would be called and the resulting message pointer and length would be passed down to the next layer the ROSE layer 3 At the ROSE layer the Invoke structure would be populated with the OPERATION value in voke identifier and other header parameters The parameter numocts value would be populated with the length of the message passed in from step 2 The parameter data field would be popu lated with the message pointer passed in from step 2 4 The encode function for Invoke would be called resulting in a fully encoded ROSE Invoke message ready for transfer across the communications link The following is a picture showing this process 262 ROSE OPERATION and ERROR Application Layer Populate specific message structure Login ARGUMENT and encode Vv Encoded message pointer and length Populate ROSE header message structure Invoke and encode Open type structure contains message pointer and length fr
394. y lt storage gt If dynamicArray a dynamic array will be used for SEQUENCE OF SET OF constructs A dynam ic array is an array that uses dynamic storage for the array elements Module Level These attributes can be applied at the module level by including them within a lt module gt section 35 Compiler Configuration File Name Values Description lt name gt lt name gt lt oid gt module name module OID object identifier This attribute identifies the module to which this section applies Either this or the lt oid gt ele ment attribute is required This attribute provides for an alternate form of module identification for the case when module name is not unique For example a given ASN 1 module may have multiple versions A unique version of the module can be identified using the OID value lt codename gt _ lt code name gt C C Java or C name This item specifies an alternate name for the module to be used in generated code By default the module name is used in the form it appears in the ASN 1 specification with hyphens converted to underscores lt include types names values names gt ASN 1 type or value names are specified as an attribute list This item allows a list of ASN 1 types and or values to be included in the generated code By default the compiler generates code for all types and values within a specification This allows the user
395. y field for equality The errBuff and errBuffSize arguments are used to describe a text buffer into which information on what fields the comparison failed on is written These arguments specify a fixed size buffer if the generated text is larger than the given buffer size the text is terminated These arguments may be omitted by passing null 0 values if you only care to know if the structures are different and not concerned with the details The return value of the function is a Boolean value that is true if the variables are equal and false if they are not Generated Copy Functions The genCopy option causes copy functions to be generated These functions can be used to copy the content of one generated type variable to another If no output file is specified with the genCopy qualifier the functions are written to separate c cpp files for each module in the source file The format of the name of each file is lt module gt Copy c cpp where lt module gt would be replaced with the name of the ASN 1 module If an output filename is specified after the genCopy qualifier all functions are written to that file The format of the name of each generated copy function is as follows asnlCopy_ lt prefix gt lt prodName gt where lt prodName gt is the name of the ASN 1 production for which the function is being generated and lt prefix gt 1s an optional prefix that can be set via a configuration file setting The configuration se
396. ymbian dll default symbian application style code Note that this usage summary shows all options for the pro version of ASNIC Some of these options are not available in the basic version To use the compiler at a minimum an ASN 1 or XSD source file must be provided The source file specification can be a full pathname or only what is necessary to qualify the file If directory information is not provided the user s current default directory is assumed If a file extension is not provided the default extension asn is appended to the name Multiple source filenames may be specified on the command line to compile a set of files The wildcard characters and are also allowed in source filenames for example the command asnic asncode gt will compile all ASN 1 files in the current working directory The source file s must contain ASN 1 productions that define ASN 1 types and or value specifi cations This file must strictly adhere to the syntax specified in ASN 1 standard ITU T X 680 The asnstd x208 command line option should be used to parse files based on the 1990 ASN 1 standard x 208 or that contain references to ROSE macro specifications The following table lists all of the command line options and what they are used for The options are shown in alphabetical order Note that the Java and C options are not shown here They are shown in their respective documents Option Argument Description 3gpp None
397. ype used to include non ASN 1 or other data within an ASN 1 encoded message This type is described using the following ASN 1 SEQUENCE EXTERNAL UNIVERSAL 8 IMPLICIT SEQUENCE direct reference OBJECT IDENTIFIER OPTIONAL indirect reference INTEGER OPTIONAL data value descriptor ObjectDescriptor OPTIONAL encoding CHOICE single ASN1l type 0 ABSTRACT SYNTAX amp Type octet aligned 1 IMPLICIT OCTET STRING arbitrary 2 IMPLICIT BIT STRING The ASNIC compiler is used to create a meta definition for this structure This code will always be generated in the asniExternal h and AsniExternal c cpp files The code will only be generated if the given ASN 1 source specification requires this definition The resulting C structure is populated just like any other compiler generated structure for working with ASN 1 data Note NOTE It is recommended that if a specification contains multiple ASN 1 source files that reference EXTERNAL all of these source files be compiled with a single ASNIC call in order to ensure that only a single copy of the Asn1 External source files are generated EMBEDDED PDV The ASN 1 EMBEDDED PDV type is a useful type used to include non ASN 1 or other data within an ASN 1 encoded message This type is described using the following ASN 1 SEQUENCE 12 Parameterized Types EmbeddedPDV UNIVERSAL 11

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