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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]. Ini-
		   tially 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  se-
       quence  element,	then the keyword "?CURRENT" is also acceptable and in-
       dicates 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: "YYMMD-
       Dhhmmss+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 se-
       lected.

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 num-
       ber  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) 2006-2025 Free Software Foundation, Inc..
       Copying	and  distribution  of this file, with or without modification,
       are permitted in	any medium without royalty provided the	copyright  no-
       tice 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			    4.20.0		    asn1_read_value(3)

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