GNU Libtasn1

https://www.gnu.org/software/libtasn1/manual/
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### Assignments file example (assign.asn1)

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Example assignments file that pairs with the definitions file, specifying values for Dss-Sig-Value.

```text
dp MYPKIX1.Dss-Sig-Value

r 42
s 47
other.x 66
other.y y1
other.y.y1 15
z (NULL)
```

--------------------------------

### ASN.1 definitions file example (pkix.asn)

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Example ASN.1 definitions file defining OtherStruct and Dss-Sig-Value, used with asn1Coding.

```asn1
MYPKIX1 { }

DEFINITIONS IMPLICIT TAGS ::=

BEGIN

OtherStruct ::= SEQUENCE {
     x       INTEGER,
     y       CHOICE {
         y1 INTEGER,
         y2 OCTET STRING }
}

Dss-Sig-Value ::= SEQUENCE {
     r       INTEGER,
     s       INTEGER,
     other   OtherStruct,
     z       INTEGER OPTIONAL
}

END
```

--------------------------------

### asn1_parser2tree function

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Starts the parse algorithm to create structures from an ASN.1 file.

```c
int asn1_parser2tree (const char * FILE, asn1_node * DEFINITIONS, char * ERROR_DESC)
```

--------------------------------

### ASN.1 Definition Example

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Naming.html

A sample ASN.1 definition used to demonstrate naming conventions for types and fields.

```ASN.1
      Example { 1 2 3 4 }

      DEFINITIONS EXPLICIT TAGS ::=

      BEGIN

      Group ::= SEQUENCE {
         id   OBJECT IDENTIFIER,
         value  Value
      }

      Value ::= SEQUENCE {
         value1  INTEGER,
         value2  BOOLEAN
      }

      END
```

--------------------------------

### Assignments file for CHOICE root element

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Example assignments file when the root element is of CHOICE type, using '' to denote the root and specifying the chosen alternative.

```text
elt PKIX1Implicit88.GeneralName

''      dNSName
dNSName example.org
```

--------------------------------

### ASN.1 Structure Definition Example

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

A sample ASN.1 definition demonstrating nested sequences and the naming convention used to access types and fields.

```text
Example { 1 2 3 4 }

DEFINITIONS EXPLICIT TAGS ::=

BEGIN

Group ::= SEQUENCE {
   id   OBJECT IDENTIFIER,
   value  Value
}

Value ::= SEQUENCE {
   value1  INTEGER,
   value2  BOOLEAN
}

END
```

--------------------------------

### asn1Decoding command invocation

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Decoding.html

Example command to decode DER data from a file named assign.out using the pkix.asn definition file.

```bash
$ asn1Decoding pkix.asn assign.out PKIX1.Dss-Sig-Value
```

--------------------------------

### Invalid ASN.1 Version Declaration

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

An example of an invalid ASN.1 declaration where the assignment operator is not properly separated.

```text
-- INCORRECT
Version ::=INTEGER
```

--------------------------------

### asn1_print_structure

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Prints the structure's tree starting from the name element inside the given structure to the specified output file.

```APIDOC
## asn1_print_structure

### Description
Prints the structure's tree starting from the name element inside the given structure to the specified output file.

### Function Signature
void asn1_print_structure(FILE *OUT, asn1_node_const STRUCTURE, const char *NAME, int MODE)

### Parameters
- **OUT** (FILE *) - Required - Pointer to the output file (e.g. stdout).
- **STRUCTURE** (asn1_node_const) - Required - Pointer to the structure that you want to visit.
- **NAME** (const char *) - Required - An element of the structure.
- **MODE** (int) - Required - Specify how much of the structure to print, can be ASN1_PRINT_NAME, ASN1_PRINT_NAME_TYPE, ASN1_PRINT_NAME_TYPE_VALUE, or ASN1_PRINT_ALL.
```

--------------------------------

### asn1_der_decoding_startEnd

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Finds the start and end positions of an element in a DER encoding string. Useful for extracting sub-sequences like tbsCertificate from an X509 certificate.

```APIDOC
## asn1_der_decoding_startEnd

### Description
Finds the start and end point of an element in a DER encoding string. If you have a DER encoding and have already used asn1_der_decoding() to fill a structure, you can find the piece of string concerning an element. Since libtasn1 3.7, ider and ider_len can be omitted if the element is already decoded.

### Function Signature
int asn1_der_decoding_startEnd(asn1_node element, const void * ider, int ider_len, const char * name_element, int * start, int * end)

### Parameters
- **element** (asn1_node) - Required - Pointer to an ASN1 element.
- **ider** (const void *) - Required - Vector that contains the DER encoding.
- **ider_len** (int) - Required - Number of bytes of ider: ider[0]..ider[len-1].
- **name_element** (const char *) - Required - An element of NAME structure.
- **start** (int *) - Required - The position of the first byte of NAME_ELEMENT decoding (ider[*start]).
- **end** (int *) - Required - The position of the last byte of NAME_ELEMENT decoding (ider[*end]).

### Returns
- ASN1_SUCCESS if DER encoding OK.
- ASN1_ELEMENT_NOT_FOUND if ELEMENT is asn1_node EMPTY or name_element is not a valid element.
- ASN1_TAG_ERROR or ASN1_DER_ERROR if the der encoding doesn't match the structure ELEMENT.
```

--------------------------------

### Invalid ASN.1 declaration

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-syntax.html

An example of an invalid declaration where the ::= token is not properly separated from the type.

```asn1
   -- INCORRECT
   Version ::=INTEGER
```

--------------------------------

### asn1_find_node

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Auxiliary-functions.html

Searches for an element called name starting from pointer. The name is composed by different identifiers separated by dots. Returns the search result or NULL if not found.

```APIDOC
## asn1_find_node

### Description
Searches for an element called `name` starting from `pointer`. The name is composed by different identifiers separated by dots. When `pointer` has a name, the first identifier must be the name of `pointer`, otherwise it must be the name of one child of `pointer`.

### Function Signature
`asn1_node asn1_find_node(asn1_node_const pointer, const char * name)`

### Parameters
- **pointer** (asn1_node_const) - Required - NODE_ASN element pointer.
- **name** (const char *) - Required - Null terminated string with the element's name to find.

### Returns
- The search result, or `NULL` if not found.
```

--------------------------------

### asn1_get_length_ber

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Function-and-Data-Index.html

DER function. Gets the length of a BER encoded value.

```APIDOC
## asn1_get_length_ber

### Description
DER function. Gets the length of a BER encoded value.

### Section
DER functions

```

--------------------------------

### asn1Decoding help output

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Decoding.html

Displays the usage syntax and available command-line options for the asn1Decoding utility.

```text
Usage: asn1Decoding [OPTION] DEFINITIONS ENCODED ASN1TYPE
Decodes DER data in ENCODED file, for the ASN1TYPE element
described in ASN.1 DEFINITIONS file, and print decoded structures.

  -b, --benchmark       perform a benchmark on decoding
  -s, --strict          use strict DER decoding
  -t, --no-time-strict  use strict DER decoding but not in time fields
  -h, --help            display this help and exit
  -v, --version         output version information and exit

Report bugs to: help-libtasn1@gnu.org
GNU Libtasn1 home page: <https://www.gnu.org/software/libtasn1/>
General help using GNU software: <https://www.gnu.org/gethelp/>
```

--------------------------------

### asn1_get_object_id_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Function-and-Data-Index.html

DER function. Gets an OBJECT IDENTIFIER value from DER data.

```APIDOC
## asn1_get_object_id_der

### Description
DER function. Gets an OBJECT IDENTIFIER value from DER data.

### Section
DER functions

```

--------------------------------

### Assignment file syntax for asn1Coding

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Shows the required syntax for the assignments file: an instance name followed by an ASN.1 definition, then name-value pairs. Use '' to denote the root element.

```text
InstanceName  Asn1Definition

nameString  value

nameString  value
...
```

--------------------------------

### asn1Coding usage and options

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Displays the command-line usage and options for asn1Coding, including -c, -o, -h, and -v.

```text
Usage: asn1Coding [OPTION] DEFINITIONS ASSIGNMENTS
Generates a DER encoding of ASN.1 DEFINITIONS file
and ASSIGNMENTS file with value assignments.

Mandatory arguments to long options are mandatory for short options too.
  -c, --check           checks the syntax only
  -o, --output=FILE     output file
  -h, --help            display this help and exit
  -v, --version         output version information and exit

Report bugs to: help-libtasn1@gnu.org
GNU Libtasn1 home page: <https://www.gnu.org/software/libtasn1/>
General help using GNU software: <https://www.gnu.org/gethelp/>
```

--------------------------------

### Clone Libtasn1 repository

Source: https://www.gnu.org/software/libtasn1

Use this command to check out the Libtasn1 source code from the GitLab repository.

```bash
$ git clone https://gitlab.com/gnutls/libtasn1.git
```

--------------------------------

### Running asn1Coding command

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Command to generate a DER encoding file named assign.out from the definitions and assignments files.

```bash
$ asn1Coding pkix.asn assign.asn1
```

--------------------------------

### asn1_check_version

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Auxiliary-functions.html

Checks that the version of the library is at minimum the requested one and returns the version string; returns NULL if the condition is not satisfied. If NULL is passed, no check is done and the version string is simply returned.

```APIDOC
## asn1_check_version

### Description
Check that the version of the library is at minimum the requested one and return the version string; return `NULL` if the condition is not satisfied. If a `NULL` is passed to this function, no check is done, but the version string is simply returned.

### Function Signature
`const char * asn1_check_version(const char * req_version)`

### Parameters
- **req_version** (const char *) - Required - Required version number, or `NULL`.

### Returns
- Version string of run-time library, or `NULL` if the run-time library does not meet the required version number.
```

--------------------------------

### Initialize asn1_node with NULL

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Library-Notes.html

The NULL constant is used for initializing variables of type asn1_node.

```c
 asn1_node definitions = NULL;
```

--------------------------------

### Correct ASN.1 Version Declaration

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

The correct syntax for an ASN.1 declaration with proper spacing around the assignment operator.

```text
Version ::= INTEGER
```

--------------------------------

### asn1Parser usage and options

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Parser.html

Shows the full usage message for asn1Parser, including its purpose, options, and contact information. Use this to understand the command-line interface and available flags.

```text
Usage: asn1Parser [OPTION] FILE
Read FILE with ASN.1 definitions and generate
a C array that is used with libtasn1 functions.

Mandatory arguments to long options are mandatory for short options too.
  -c, --check           checks the syntax only
  -o, --output=FILE     output file
  -n, --name=NAME       array name
  -h, --help            display this help and exit
  -v, --version         output version information and exit

Report bugs to: help-libtasn1@gnu.org
GNU Libtasn1 home page: <https://www.gnu.org/software/libtasn1/>
General help using GNU software: <https://www.gnu.org/gethelp/>

```

--------------------------------

### asn1_array2tree

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Creates the structures needed to manage ASN.1 definitions from an array of ASN.1 declarations.

```APIDOC
## asn1_array2tree

### Description
Creates the structures needed to manage the ASN.1 definitions. `array` is a vector created by `asn1_parser2array()`.

### Function Signature
`int asn1_array2tree (const asn1_static_node * array, asn1_node * definitions, char * errorDescription)`

### Parameters
- **array** (const asn1_static_node *) - Required - Specify the array that contains ASN.1 declarations.
- **definitions** (asn1_node *) - Required - Return the pointer to the structure created by *ARRAY ASN.1 declarations.
- **errorDescription** (char *) - Required - Return the error description.

### Returns
- `ASN1_SUCCESS` if structure was created correctly.
- `ASN1_ELEMENT_NOT_EMPTY` if *definitions not NULL.
- `ASN1_IDENTIFIER_NOT_FOUND` if in the file there is an identifier that is not defined (see `errorDescription` for more information).
- `ASN1_ARRAY_ERROR` if the array pointed by `array` is wrong.
```

--------------------------------

### asn1Coding [OPTION] DEFINITIONS ASSIGNMENTS

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Invoking-asn1Coding.html

Generates a DER encoding from a file with ASN.1 definitions and another one with assignments. The output is a binary file with the DER encoding.

```APIDOC
## asn1Coding [OPTION] DEFINITIONS ASSIGNMENTS

### Description
Generates a DER encoding from a file with ASN.1 definitions and another one with assignments. The output file is a binary file with the DER encoding.

### Method
CLI

### Endpoint
asn1Coding [OPTION] DEFINITIONS ASSIGNMENTS

### Parameters
#### Options
- **-c, --check** - Checks the syntax only.
- **-o, --output=FILE** - Output file.
- **-h, --help** - Display this help and exit.
- **-v, --version** - Output version information and exit.

### Request Example
```
$ asn1Coding pkix.asn assign.asn1
```

### Response
#### Success Response
Generates a binary file with the DER encoding. The output file name is specified by the -o option, or defaults to a file named 'assign.out' as shown in the example.

#### Response Example
```
assign.out
```

```

--------------------------------

### Invoke asn1Coding

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

The asn1Coding utility generates a DER encoding from an ASN.1 definitions file and an assignments file.

```bash
Usage: asn1Coding [OPTION] DEFINITIONS ASSIGNMENTS
Generates a DER encoding of ASN.1 DEFINITIONS file
and ASSIGNMENTS file with value assignments.

Mandatory arguments to long options are mandatory for short options too.
  -c, --check           checks the syntax only
  -o, --output=FILE     output file
  -h, --help            display this help and exit
  -v, --version         output version information and exit
```

--------------------------------

### asn1Parser

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Reads a file with ASN.1 definitions and generates a C array for use with libtasn1 functions. Supports syntax checking and custom output file and array name.

```APIDOC
## asn1Parser

### Description
Reads a file with ASN.1 definitions and generates a C array for use with libtasn1 functions. Supports syntax checking and custom output file and array name.

### Usage
asn1Parser [OPTION] FILE

### Options
- **-c, --check** - Checks the syntax only.
- **-o, --output=FILE** - Output file.
- **-n, --name=NAME** - Array name.
- **-h, --help** - Display help and exit.
- **-v, --version** - Output version information and exit.

### Arguments
- **FILE** - The input file with ASN.1 definitions.

### Example
```bash
asn1Parser -o output.c -n my_array definitions.asn
```
```

--------------------------------

### Allocate error description buffer

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Functions requiring an errorDescription argument need a pre-allocated buffer of at least ASN1_MAX_ERROR_DESCRIPTION_SIZE bytes.

```c
char description[ASN1_MAX_ERROR_DESCRIPTION_SIZE];
```

--------------------------------

### Invoke asn1Decoding

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

The asn1Decoding utility generates an ASN.1 structure from an ASN.1 definitions file and a binary DER encoded file.

```bash
Usage: asn1Decoding [OPTION] DEFINITIONS ENCODED ASN1TYPE
Decodes DER data in ENCODED file, for the ASN1TYPE element
described in ASN.1 DEFINITIONS file, and print decoded structures.

  -b, --benchmark       perform a benchmark on decoding
  -s, --strict          use strict DER decoding
  -t, --no-time-strict  use strict DER decoding but not in time fields
  -h, --help            display this help and exit
  -v, --version         output version information and exit
```

--------------------------------

### asn1_expand_any_defined_by

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Expands every ANY DEFINED BY element in a structure created from DER decoding. The element ANY must be defined by an OBJECT IDENTIFIER.

```APIDOC
## asn1_expand_any_defined_by

### Description
Expands every "ANY DEFINED BY" element of a structure created from a DER decoding process (asn1_der_decoding function). The element ANY must be defined by an OBJECT IDENTIFIER. The type used to expand the element ANY is the first one following the definition of the actual value of the OBJECT IDENTIFIER.

### Function Signature
int asn1_expand_any_defined_by(asn1_node_const definitions, asn1_node * element)

### Parameters
- **definitions** (asn1_node_const) - Required - ASN1 definitions.
- **element** (asn1_node *) - Required - Pointer to an ASN1 structure.

### Returns
- ASN1_SUCCESS if Substitution OK.
- ASN1_ERROR_TYPE_ANY if some "ANY DEFINED BY" element couldn't be expanded due to a problem in OBJECT_ID -> TYPE association.
- Other error codes depending on DER decoding.
```

--------------------------------

### asn1_print_structure

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Prints the structure's tree to a file descriptor.

```APIDOC
## asn1_print_structure

### Description
Prints on the `out` file descriptor the structure's tree starting from the `name` element inside the structure `structure`.

### Function Signature
`void asn1_print_structure (FILE * out, asn1_node_const structure, const char * name, int mode)`

### Parameters
- **out** (FILE *) - Required - Pointer to the output file (e.g. stdout).
- **structure** (asn1_node_const) - Required - Pointer to the structure that you want to visit.
- **name** (const char *) - Required - An element of the structure.
- **mode** (int) - Required - Specify how much of the structure to print, can be `ASN1_PRINT_NAME`, `ASN1_PRINT_NAME_TYPE`, `ASN1_PRINT_NAME_TYPE_VALUE`, or `ASN1_PRINT_ALL`.

### Returns
- void
```

--------------------------------

### Invoke asn1Parser

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

The asn1Parser utility reads an ASN.1 definitions file and generates a C array for use with libtasn1 functions.

```bash
Usage: asn1Parser [OPTION] FILE
Read FILE with ASN.1 definitions and generate
a C array that is used with libtasn1 functions.

Mandatory arguments to long options are mandatory for short options too.
  -c, --check           checks the syntax only
  -o, --output=FILE     output file
  -n, --name=NAME       array name
  -h, --help            display this help and exit
  -v, --version         output version information and exit
```

--------------------------------

### asn1_perror

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Error-handling-functions.html

Prints a string to stderr with a description of an error returned by a libtasn1 function. Similar to perror().

```APIDOC
## asn1_perror

### Description
Prints a string to stderr with a description of an error returned by a libtasn1 function. This function is like perror().

### Function Signature
void asn1_perror(int error)

### Parameters
- **error** (int) - Required - An error returned by a libtasn1 function.

### Since
1.6

```

--------------------------------

### asn1_parser2array function

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Generates a C structure definition from an ASN.1 file.

```c
int asn1_parser2array (const char * INPUTFILENAME, const char * OUTPUTFILENAME, const char * VECTORNAME, char * ERROR_DESC)
```

--------------------------------

### asn1_parser2tree

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-schema-functions.html

Parses an ASN.1 file and creates a tree structure. Returns ASN1_SUCCESS on success or an error code on failure.

```APIDOC
## asn1_parser2tree

### Description
Parses an ASN.1 file and creates the structures needed to manage the definitions included in the file. Returns ASN1_SUCCESS if the file has correct syntax and every identifier is known.

### Function Signature
`int asn1_parser2tree (const char *file, asn1_node *definitions, char *error_desc)`

### Parameters
- **file** (const char *) - Required - Specify the path and the name of file that contains ASN.1 declarations.
- **definitions** (asn1_node *) - Required - Return the pointer to the structure created from "file" ASN.1 declarations.
- **error_desc** (char *) - Required - Return the error description or an empty string if success.

### Returns
- `ASN1_SUCCESS` if the file has a correct syntax and every identifier is known.
- `ASN1_ELEMENT_NOT_EMPTY` if `definitions` not `NULL`.
- `ASN1_FILE_NOT_FOUND` if an error occurred while opening `file`.
- `ASN1_SYNTAX_ERROR` if the syntax is not correct.
- `ASN1_IDENTIFIER_NOT_FOUND` if in the file there is an identifier that is not defined.
- `ASN1_NAME_TOO_LONG` if in the file there is an identifier with more than `ASN1_MAX_NAME_SIZE` characters.
```

--------------------------------

### asn1_parser2array

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-schema-functions.html

Generates a C structure from an ASN.1 file, creating a file containing a C vector to manage the definitions. Returns ASN1_SUCCESS on success or an error code on failure.

```APIDOC
## asn1_parser2array

### Description
Generates a C structure from an ASN.1 file. Creates a file containing a C vector to use to manage the definitions included in the input file. If inputFileName is "/aa/bb/xx.yy" and outputFileName is NULL, the file created is "/aa/bb/xx_asn1_tab.c". If vectorName is NULL the vector name will be "xx_asn1_tab".

### Function Signature
`int asn1_parser2array (const char *inputFileName, const char *outputFileName, const char *vectorName, char *error_desc)`

### Parameters
- **inputFileName** (const char *) - Required - Specify the path and the name of file that contains ASN.1 declarations.
- **outputFileName** (const char *) - Required - Specify the path and the name of file that will contain the C vector definition.
- **vectorName** (const char *) - Required - Specify the name of the C vector.
- **error_desc** (char *) - Required - Return the error description or an empty string if success.

### Returns
- `ASN1_SUCCESS` if the file has a correct syntax and every identifier is known.
- `ASN1_FILE_NOT_FOUND` if an error occurred while opening `inputFileName`.
- `ASN1_SYNTAX_ERROR` if the syntax is not correct.
- `ASN1_IDENTIFIER_NOT_FOUND` if in the file there is an identifier that is not defined.
- `ASN1_NAME_TOO_LONG` if in the file there is an identifier with more than `ASN1_MAX_NAME_SIZE` characters.
```

--------------------------------

### asn1_create_element

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Creates a structure of a specified type from ASN.1 definitions.

```APIDOC
## asn1_create_element

### Description
Creates a structure of type `source_name`. Example using "pkix.asn": rc = asn1_create_element(cert_def, "PKIX1.Certificate", certptr);

### Function Signature
`int asn1_create_element (asn1_node_const definitions, const char * source_name, asn1_node * element)`

### Parameters
- **definitions** (asn1_node_const) - Required - Pointer to the structure returned by "parser_asn1" function.
- **source_name** (const char *) - Required - The name of the type of the new structure (must be inside p_structure).
- **element** (asn1_node *) - Required - Pointer to the structure created.

### Returns
- `ASN1_SUCCESS` if creation OK.
- `ASN1_ELEMENT_NOT_FOUND` if `source_name` is not known.
```

--------------------------------

### asn1_array2tree function

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Creates structures from an array generated by asn1_parser2array.

```c
int asn1_array2tree (const asn1_static_node * ARRAY, asn1_node * DEFINITIONS, char * ERRORDESCRIPTION)
```

--------------------------------

### asn1_dup_node

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Creates a deep copy of an asn1_node variable. Returns NULL on failure.

```APIDOC
## asn1_dup_node

### Description
Creates a deep copy of an asn1_node variable. This function will return an exact copy of the provided structure.

### Function Signature
`asn1_node asn1_dup_node(asn1_node_const src, const char * src_name)`

### Parameters
- **src** (asn1_node_const) - Required - Source asn1 node.
- **src_name** (const char *) - Required - Field name in source node.

### Returns
- **asn1_node** - Return NULL on failure.
```

--------------------------------

### asn1_check_version

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Function-and-Data-Index.html

Auxiliary function. Checks the version of the libtasn1 library.

```APIDOC
## asn1_check_version

### Description
Auxiliary function. Checks the version of the libtasn1 library.

### Section
Auxiliary functions

```

--------------------------------

### asn1_find_structure_from_oid

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Searches for a structure defined just after an OID definition.

```APIDOC
## asn1_find_structure_from_oid

### Description
Search the structure that is defined just after an OID definition.

### Function Signature
`const char * asn1_find_structure_from_oid (asn1_node_const definitions, const char * oidValue)`

### Parameters
- **definitions** (asn1_node_const) - Required - ASN1 definitions.
- **oidValue** (const char *) - Required - Value of the OID to search (e.g. "1.2.3.4").

### Returns
- `NULL` when `oidValue` not found, otherwise the pointer to a constant string that contains the element name defined just after the OID.
```

--------------------------------

### ASN.1 definition structure

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-syntax.html

The standard structure for defining ASN.1 modules, requiring a name, tags, and a body enclosed in BEGIN and END.

```asn1
      definitions_name {<object definition>}

      DEFINITIONS <EXPLICIT or IMPLICIT> TAGS ::=

      BEGIN

      <type and constants definitions>

      END
```

--------------------------------

### asn1_encode_simple_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Creates the DER encoding for various simple ASN.1 types like strings. It stores the tag and length in a provided buffer.

```APIDOC
## asn1_encode_simple_der

### Description
Creates the DER encoding for various simple ASN.1 types like strings etc. It stores the tag and length in `tl`, which should have space for at least `ASN1_MAX_TL_SIZE` bytes. Initially `tl_len` should contain the size of `tl`. The complete DER encoding should consist of the value in `tl` appended with the provided `str`.

### Function Signature
`int asn1_encode_simple_der (unsigned int etype, const unsigned char * str, unsigned int str_len, unsigned char * tl, unsigned int * tl_len)`

### Parameters
- **etype** (unsigned int) - Required - The type of the string to be encoded (ASN1_ETYPE_).
- **str** (const unsigned char *) - Required - The string data.
- **str_len** (unsigned int) - Required - The string length.
- **tl** (unsigned char *) - Required - The encoded tag and length.
- **tl_len** (unsigned int *) - Required - The bytes of the `tl` field.

### Returns
`ASN1_SUCCESS` if successful or an error value.
```

--------------------------------

### asn1_strerror

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Error-handling-functions.html

Returns a string with a description of an error returned by a libtasn1 function. Similar to strerror().

```APIDOC
## asn1_strerror

### Description
Returns a string with a description of an error returned by a libtasn1 function. This function is similar to strerror.

### Function Signature
const char * asn1_strerror(int error)

### Parameters
- **error** (int) - Required - An error returned by a libtasn1 function.

### Returns
Pointer to static zero-terminated string describing error code.

### Since
1.6

```

--------------------------------

### asn1_der_decoding2

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Fills an ASN1 structure with values from a DER encoding string. The structure must be created with asn1_create_element().

```APIDOC
## asn1_der_decoding2

### Description
Fill the structure * 'element' with values of a DER encoding string. The structure must just be created with function 'asn1_create_element()'. If 'ASN1_DECODE_FLAG_ALLOW_PADDING' flag is set then the function will ignore padding after the decoded DER data. Upon a successful return the value of * 'max_ider_len' will be set to the number of bytes decoded.

### Function Signature
```c
int asn1_der_decoding2 (asn1_node * ELEMENT, const void * IDER, int * MAX_IDER_LEN, unsigned int FLAGS, char * ERRORDESCRIPTION);
```

### Parameters
- **ELEMENT** (asn1_node *) - Input/Output - Pointer to an ASN1 structure.
- **IDER** (const void *) - Input - Vector that contains the DER encoding.
- **MAX_IDER_LEN** (int *) - Input/Output - Pointer to an integer giving the information about the maximal number of bytes occupied by * 'ider'. The real size of the DER encoding is returned through this pointer.
- **FLAGS** (unsigned int) - Input - Flags controlling the behaviour of the function.
- **ERRORDESCRIPTION** (char *) - Output - Null-terminated string contains details when an error occurred.

### Returns
Returns 'ASN1_SUCCESS' on success, or an error.
```

--------------------------------

### asn1_get_bit_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Extracts a BIT SEQUENCE from DER data. Returns ASN1_SUCCESS on success or an error.

```APIDOC
## asn1_get_bit_der

### Description
Extract a BIT SEQUENCE from DER data.

### Function Signature
int asn1_get_bit_der(const unsigned char * der, int der_len, int * ret_len, unsigned char * str, int str_size, int * bit_len)

### Parameters
- **der** (const unsigned char *) - Input - DER data to decode containing the BIT SEQUENCE.
- **der_len** (int) - Input - Length of DER data to decode.
- **ret_len** (int *) - Output - Output variable containing the length of the DER data.
- **str** (unsigned char *) - Output - Pre-allocated output buffer to put decoded BIT SEQUENCE in.
- **str_size** (int) - Input - Length of pre-allocated output buffer.
- **bit_len** (int *) - Output - Output variable containing the size of the BIT SEQUENCE.

### Returns
ASN1_SUCCESS on success, or an error.
```

--------------------------------

### asn1_bit_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Creates a length-value DER encoding for input data as it would have been for a BIT STRING, without the BIT STRING tag. The output buffer must be large enough; use asn1_length_der to determine the required size.

```APIDOC
## asn1_bit_der

### Description
Creates a length-value DER encoding for the input data as it would have been for a BIT STRING. The DER encoded data will be copied in `der`. Note that the BIT STRING tag is not included in the output. This function does not return any value because it is expected that `der_len` will contain enough bytes to store the string plus the DER encoding. The DER encoding size can be obtained using `asn1_length_der()`.

### Function Signature
`void asn1_bit_der (const unsigned char * str, int bit_len, unsigned char * der, int * der_len)`

### Parameters
- **str** (const unsigned char *) - Required - BIT string.
- **bit_len** (int) - Required - Number of meaningful bits in STR.
- **der** (unsigned char *) - Required - String returned.
- **der_len** (int *) - Required - Number of meaningful bytes of DER (der[0]..der[ans_len-1]).

### Returns
This function does not return a value.
```

--------------------------------

### asn1_number_of_elements

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Counts the number of elements of a sub-structure with names equal to "?1", "?2", ...

```APIDOC
## asn1_number_of_elements

### Description
Counts the number of elements of a sub-structure called NAME with names equal to "?1","?2", ...

### Function Signature
`int asn1_number_of_elements (asn1_node_const element, const char * name, int * num)`

### Parameters
- **element** (asn1_node_const) - Required - Pointer to the root of an ASN1 structure.
- **name** (const char *) - Required - The name of a sub-structure of ROOT.
- **num** (int *) - Required - Pointer to an integer where the result will be stored.

### Returns
- `ASN1_SUCCESS` if successful.
- `ASN1_ELEMENT_NOT_FOUND` if `name` is not known.
- `ASN1_GENERIC_ERROR` if pointer `num` is `NULL`.
```

--------------------------------

### asn1_copy_node

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-field-functions.html

Creates a deep copy of an asn1_node variable.

```APIDOC
## asn1_copy_node

### Description
Create a deep copy of a asn1_node variable. That function requires `dst` to be expanded using `asn1_create_element()`.

### Function Signature
`int asn1_copy_node (asn1_node dst, const char * dst_name, asn1_node_const src, const char * src_name)`

### Parameters
- **dst** (asn1_node) - Required - Destination asn1 node.
- **dst_name** (const char *) - Required - Field name in destination node.
- **src** (asn1_node_const) - Required - Source asn1 node.
- **src_name** (const char *) - Required - Field name in source node.

### Returns
- Return `ASN1_SUCCESS` on success.
```

--------------------------------

### asn1_copy_node

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Function-and-Data-Index.html

ASN.1 field function. Copies an ASN.1 node.

```APIDOC
## asn1_copy_node

### Description
ASN.1 field function. Copies an ASN.1 node.

### Section
ASN.1 field functions

```

--------------------------------

### Correct ASN.1 declaration

Source: https://www.gnu.org/software/libtasn1/manual/html_node/ASN_002e1-syntax.html

The correct form of the declaration ensuring the ::= token is separated from other elements.

```asn1
   Version ::= INTEGER
```

--------------------------------

### asn1_expand_any_defined_by

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Expands an 'ANY DEFINED BY' element of a structure created from a DER decoding process. The type used for expansion is the first one following the definition of the actual value of the OBJECT IDENTIFIER indicated by OBJECTNAME.

```APIDOC
## asn1_expand_any_defined_by

### Description
Expands an "ANY DEFINED BY" element of a structure created from a DER decoding process (the asn1_der_decoding() function). The type used for expansion is the first one following the definition of the actual value of the OBJECT IDENTIFIER indicated by OBJECTNAME.

### Function Signature
int asn1_expand_any_defined_by (asn1_node_const DEFINITIONS, asn1_node * ELEMENT, const char * OBJECTNAME)

### Parameters
- **DEFINITIONS** (asn1_node_const) - Required - ASN1 definitions
- **ELEMENT** (asn1_node *) - Required - pointer to an ASN1 structure
- **OBJECTNAME** (const char *) - Required - name of the OBJECT IDENTIFIER field to use to define the type for expansion.

### Returns
ASN1_SUCCESS if Substitution OK, ASN1_ERROR_TYPE_ANY if some "ANY DEFINED BY" element couldn't be expanded due to a problem in OBJECT_ID -> TYPE association, or other error codes depending on DER decoding.
```

--------------------------------

### asn1_der_decoding2

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Fills an ASN1 structure with values from a DER encoding string. Supports flags for padding and strict DER. Returns ASN1_SUCCESS on success or specific error codes.

```APIDOC
## asn1_der_decoding2

### Description
Fill the structure *element with values of a DER encoding string. The structure must just be created with function asn1_create_element(). If ASN1_DECODE_FLAG_ALLOW_PADDING flag is set then the function will ignore padding after the decoded DER data. Upon a successful return the value of *max_ider_len will be set to the number of bytes decoded. If ASN1_DECODE_FLAG_STRICT_DER flag is set then the function will not decode any BER-encoded elements.

### Function Signature
int asn1_der_decoding2(asn1_node * element, const void * ider, int * max_ider_len, unsigned int flags, char * errorDescription)

### Parameters
- **element** (asn1_node *) - Input/Output - Pointer to an ASN1 structure.
- **ider** (const void *) - Input - Vector that contains the DER encoding.
- **max_ider_len** (int *) - Input/Output - Pointer to an integer giving the information about the maximal number of bytes occupied by *ider. The real size of the DER encoding is returned through this pointer.
- **flags** (unsigned int) - Input - Flags controlling the behaviour of the function.
- **errorDescription** (char *) - Output - Null-terminated string contains details when an error occurred.

### Returns
ASN1_SUCCESS if DER encoding OK, ASN1_ELEMENT_NOT_FOUND if ELEMENT is NULL, and ASN1_TAG_ERROR or ASN1_DER_ERROR if the der encoding doesn't match the structure name (*ELEMENT deleted).
```

--------------------------------

### asn1_get_tag_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Decodes the class and tag from DER data. Returns ASN1_SUCCESS on success or an error.

```APIDOC
## asn1_get_tag_der

### Description
Decode the class and TAG from DER code.

### Function Signature
int asn1_get_tag_der(const unsigned char * der, int der_len, unsigned char * cls, int * len, unsigned long * tag)

### Parameters
- **der** (const unsigned char *) - Input - DER data to decode.
- **der_len** (int) - Input - Length of DER data to decode.
- **cls** (unsigned char *) - Output - Output variable containing decoded class.
- **len** (int *) - Output - Output variable containing the length of the DER TAG data.
- **tag** (unsigned long *) - Output - Output variable containing the decoded tag (may be NULL).

### Returns
Returns ASN1_SUCCESS on success, or an error.
```

--------------------------------

### asn1_find_structure_from_oid

Source: https://www.gnu.org/software/libtasn1/manual/libtasn1.txt

Searches the structure that is defined just after an OID definition. Returns NULL when oidValue is not found, otherwise the pointer to a constant string that contains the element name defined just after the OID.

```APIDOC
## asn1_find_structure_from_oid

### Description
Searches the structure that is defined just after an OID definition.

### Function Signature
const char *asn1_find_structure_from_oid(asn1_node_const DEFINITIONS, const char *OIDVALUE)

### Parameters
- **DEFINITIONS** (asn1_node_const) - Required - ASN1 definitions.
- **OIDVALUE** (const char *) - Required - Value of the OID to search (e.g. "1.2.3.4").

### Returns
- **NULL** - When oidValue not found.
- **const char *** - Pointer to a constant string that contains the element name defined just after the OID.
```

--------------------------------

### asn1_octet_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Creates a length-value DER encoding for input data, without the OCTET STRING tag. The output buffer must be large enough; use asn1_length_der to determine the required size.

```APIDOC
## asn1_octet_der

### Description
Creates a length-value DER encoding for the input data. The DER encoding of the input data will be placed in the `der` variable. Note that the OCTET STRING tag is not included in the output. This function does not return any value because it is expected that `der_len` will contain enough bytes to store the string plus the DER encoding. The DER encoding size can be obtained using `asn1_length_der()`.

### Function Signature
`void asn1_octet_der (const unsigned char * str, int str_len, unsigned char * der, int * der_len)`

### Parameters
- **str** (const unsigned char *) - Required - The input data.
- **str_len** (int) - Required - STR length (str[0]..str[*str_len-1]).
- **der** (unsigned char *) - Required - Encoded string returned.
- **der_len** (int *) - Required - Number of meaningful bytes of DER (der[0]..der[der_len-1]).

### Returns
This function does not return a value.
```

--------------------------------

### asn1_parser2array

Source: https://www.gnu.org/software/libtasn1/manual/html_node/Function-and-Data-Index.html

ASN.1 schema function. Parses an ASN.1 schema into an array.

```APIDOC
## asn1_parser2array

### Description
ASN.1 schema function. Parses an ASN.1 schema into an array.

### Section
ASN.1 schema functions

```

--------------------------------

### asn1_get_octet_der

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Extracts an OCTET SEQUENCE from DER data, expecting data past the tag field. Returns ASN1_SUCCESS on success or an error.

```APIDOC
## asn1_get_octet_der

### Description
Extract an OCTET SEQUENCE from DER data. Note that this function expects the DER data past the tag field, i.e., the length and content octets.

### Function Signature
int asn1_get_octet_der(const unsigned char * der, int der_len, int * ret_len, unsigned char * str, int str_size, int * str_len)

### Parameters
- **der** (const unsigned char *) - Input - DER data to decode containing the OCTET SEQUENCE.
- **der_len** (int) - Input - The length of the der data to decode.
- **ret_len** (int *) - Output - Output variable containing the encoded length of the DER data.
- **str** (unsigned char *) - Output - Pre-allocated output buffer to put decoded OCTET SEQUENCE in.
- **str_size** (int) - Input - Length of pre-allocated output buffer.
- **str_len** (int *) - Output - Output variable containing the length of the contents of the OCTET SEQUENCE.

### Returns
Returns ASN1_SUCCESS on success, or an error.
```

--------------------------------

### asn1_der_decoding

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Decodes a DER encoding string into an ASN.1 structure. The structure must be created with asn1_create_element().

```APIDOC
## asn1_der_decoding

### Description
Decodes a DER encoding string into an ASN.1 structure. The structure must be created with asn1_create_element().

### Function Signature
int asn1_der_decoding(asn1_node * element, const void * ider, int ider_len, char * errorDescription)

### Parameters
- **element** (asn1_node *) - Required - Pointer to an ASN1 structure.
- **ider** (const void *) - Required - Vector that contains the DER encoding.
- **ider_len** (int) - Required - Number of bytes of ider: ider[0]..ider[len-1].
- **errorDescription** (char *) - Required - Null-terminated string contains details when an error occurred.

### Returns
- ASN1_SUCCESS if DER encoding OK.
- ASN1_ELEMENT_NOT_FOUND if ELEMENT is NULL.
- ASN1_TAG_ERROR or ASN1_DER_ERROR if the der encoding doesn't match the structure name (ELEMENT deleted).
```

--------------------------------

### asn1_der_coding

Source: https://www.gnu.org/software/libtasn1/manual/html_node/DER-functions.html

Creates the DER encoding for a named structure inside an ASN.1 element. The output buffer must be pre-allocated; on insufficient size, the required length is returned.

```APIDOC
## asn1_der_coding

### Description
Creates the DER encoding for the NAME structure (inside *POINTER structure).

### Function Signature
`int asn1_der_coding (asn1_node_const element, const char * name, void * ider, int * len, char * ErrorDescription)`

### Parameters
- **element** (asn1_node_const) - Required - Pointer to an ASN1 element.
- **name** (const char *) - Required - The name of the structure you want to encode (it must be inside *POINTER).
- **ider** (void *) - Required - Vector that will contain the DER encoding. DER must be a pointer to memory cells already allocated.
- **len** (int *) - Required - Number of bytes of *`ider`: `ider`[0]..`ider`[len-1], Initially holds the sizeof of der vector.
- **ErrorDescription** (char *) - Required - Return the error description or an empty string if success.

### Returns
`ASN1_SUCCESS` if DER encoding OK, `ASN1_ELEMENT_NOT_FOUND` if `name` is not a valid element, `ASN1_VALUE_NOT_FOUND` if there is an element without a value, `ASN1_MEM_ERROR` if the `ider` vector isn't big enough and in this case `len` will contain the length needed.
```
Tokens:
Raw