NAME
asn1_read_value - Returns the value of one element inside a structure
SYNOPSIS
#include <libtasn1.h>
asn1_retCode asn1_read_value(ASN1_TYPE root, const char * name, void * ivalue, int * len);
ARGUMENTS
| ASN1_TYPE root | pointer to a structure. |
| const char * name | the name of the element inside a structure that you want to read. |
| void * ivalue | vector that will contain the element’s content, must be a pointer to memory cells already allocated. |
| int * len | number of bytes of *value: value[0]..value[len-1]. Initialy holds the sizeof value. |
DESCRIPTION
Returns the value of one element inside a structure.
If an element is OPTIONAL and the function "read_value" returns ASN1_ELEMENT_NOT_FOUND, it means that this element wasn’t present in the der encoding that created the structure. The first element of a SEQUENCE_OF or SET_OF is named "?1". The second one "?2" and so on.
INTEGER
VALUE will contain a two’s complement form integer.
integer=-1 -> value[0]=0xFF , len=1. integer=1 -> value[0]=0x01 , len=1.
ENUMERATED
As INTEGER (but only with not negative numbers).
BOOLEAN
VALUE will be the null terminated string "TRUE" or "FALSE" and LEN=5 or LEN=6.
OBJECT IDENTIFIER
VALUE will be a null terminated string with each number separated by a dot (i.e. "1.2.3.543.1").
LEN = strlen(VALUE)+1
UTCTIME
VALUE will be a null terminated string in one of these formats: "YYMMDDhhmmss+hh’mm’" or "YYMMDDhhmmss-hh’mm’". LEN=strlen(VALUE)+1.
GENERALIZEDTIME
VALUE will be a null terminated string in the same format used to set the value.
OCTET STRING
VALUE will contain the octet string and LEN will be the number of octets.
GENERALSTRING
VALUE will contain the generalstring and LEN will be the number of octets.
BIT STRING
VALUE will contain the bit string organized by bytes and LEN will be the number of bits.
CHOICE
If NAME indicates a choice type, VALUE will specify the alternative selected.
ANY
If NAME indicates an any type, VALUE will indicate the DER encoding of the structure actually used.
RETURNS
ASN1_SUCCESS
Set value OK.
ASN1_ELEMENT_NOT_FOUND
NAME is not a valid element.
ASN1_VALUE_NOT_FOUND
There isn’t any value for the element selected.
ASN1_MEM_ERROR
The value vector isn’t big enough to store the result. In this case LEN will contain the number of bytes needed.
COPYRIGHT
Copyright © 2006, 2007, 2008, 2009 Free Software Foundation, Inc.. Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.
SEE ALSO
The full documentation for libtasn1 is maintained as a Texinfo manual. If the info and libtasn1 programs are properly installed at your site, the command
| info libtasn1 | |
