@deftypefun {int} {gnutls_ocsp_req_set_extension} (gnutls_ocsp_req_t @var{req}, const char * @var{oid}, unsigned int @var{critical}, const gnutls_datum_t * @var{data})
@var{req}: should contain a @code{gnutls_ocsp_req_t}  type

@var{oid}: buffer with OID of extension as a string.

@var{critical}: critical flag, normally false.

@var{data}: the extension data

This function will add an extension to the OCSP request.  Calling
this function multiple times for the same OID will overwrite values
from earlier calls.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code is returned.
@end deftypefun