gnutls_x509_crt_get_subject_alt_name(3)

Linux manual pages	Section 3

Name

gnutls_x509_crt_get_subject_alt_name — Get certificate's alternative name, if any

Synopsis

#include <gnutls/x509.h>

`int gnutls_x509_crt_get_subject_alt_name(`	gnutls_x509_crt_t `cert`,
	unsigned int `seq`,
	void * `ret`,
	size_t * `ret_size`,
	unsigned int * `critical)`;

ARGUMENTS

gnutls_x509_crt_t cert: should contain a gnutls_x509_crt_t structure
unsigned int seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
void * ret: is the place where the alternative name will be copied to
size_t * ret_size: holds the size of ret.
unsigned int * critical: will be non zero if the extension is marked as critical (may be null)

DESCRIPTION

This function will return the alternative names, contained in the given certificate.

This is specified in X509v3 Certificate Extensions. GNUTLS will return the Alternative name (2.5.29.17), or a negative error code.

When the SAN type is otherName, it will extract the data in the otherName's value field, and GNUTLS_SAN_OTHERNAME is returned. You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get the corresponding OID and the "virtual" SAN types (e.g., GNUTLS_SAN_OTHERNAME_XMPP).

If an otherName OID is known, the data will be decoded. Otherwise the returned data will be DER encoded, and you will have to decode it yourself. Currently, only the RFC 3920 id−on−xmppAddr SAN is recognized.

RETURNS

the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t. It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ret_size is not large enough to hold the value. In that case ret_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

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