NAME

       asn1_read_value_type - API function

SYNOPSIS

       #include <libtasn1.h>

       int  asn1_read_value_type(asn1_node_const root, const char * name, void * ivalue, int * len, unsigned int
       * etype);

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.

       unsigned int * etype
                   The type of the value read (ASN1_ETYPE)

DESCRIPTION

       Returns the type and 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/