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 © 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/