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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]. Initially holds the sizeof value. DESCRIPTION Returns the value of one element inside a structure. If an element is OP- TIONAL 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 se- quence 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: "YYMMDDhh- mmss+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 num- ber 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 ele- ment 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 func- tion 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 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 4.21.0 asn1_read_value(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | INTEGER | ENUMERATED | BOOLEAN | UTCTIME | GENERALIZEDTIME | GENERALSTRING | CHOICE | ANY | RETURNS | COPYRIGHT | SEE ALSO
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