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asn1_read_value(3)                 libtasn1                 asn1_read_value(3)

NAME
       asn1_read_value - API function

SYNOPSIS
       #include <libtasn1.h>

       int asn1_read_value(asn1_node_const root, const char * name, void *
       ivalue, int * len);

ARGUMENTS
       asn1_node_const 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 (may be NULL).

       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 this 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. If the  root provided is a node to specific
       sequence element, then the keyword "?CURRENT" is also acceptable and
       indicates the current sequence element of this node.

       Note that there can be valid values with length zero. In these case
       this function will succeed and  len will be zero.

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 if value is returned, ASN1_ELEMENT_NOT_FOUND if  name is
       not a valid element, ASN1_VALUE_NOT_FOUND if there isn't any value for
       the element selected, and ASN1_MEM_ERROR if The value vector isn't big
       enough to store the result, and in this case  len will contain the
       number of bytes needed. On the occasion that the stored data are of
       zero-length this function may return ASN1_SUCCESS even if the provided
       len is zero.

COPYRIGHT
       Copyright (C) 2006-2022 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

       should give you access to the complete manual.  As an alternative you
       may obtain the manual from:

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

libtasn1                            4.19.0                  asn1_read_value(3)