int gnutls_x509_crt_get_extension_info(gnutls_x509_crt_t cert, int indx, void * oid, size_t * sizeof_oid, int * critical);
should contain a gnutls_x509_crt_t structure
Specifies which extension OID to send. Use zero to get the first one.
void * oid
a pointer to a structure to hold the OID
size_t * sizeof_oid
initially holds the maximum size of oid, on return
holds actual size of oid.
int * critical
output variable with critical flag, may be NULL.
This function will return the requested extension OID in the
certificate, and the critical flag for it. The extension OID will
be stored as a string in the provided buffer. Use
gnutls_x509_crt_get_extension_data() to extract the data.
If the buffer provided is not long enough to hold the output, then
*sizeof_oid is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be
On success, GNUTLS_E_SUCCESS (zero) is returned,
otherwise an error code is returned. If you have reached the
last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
will be returned.