@deftypefun {void} {gnutls_session_set_verify_function} (gnutls_session_t @var{session}, gnutls_certificate_verify_function * @var{func}) @var{session}: is a @code{gnutls_session_t} type. @var{func}: is the callback function This function sets a callback to be called when peer's certificate has been received in order to verify it on receipt rather than doing after the handshake is completed. This overrides any callback set using @code{gnutls_certificate_set_verify_function()} . The callback's function prototype is: int (*callback)(gnutls_session_t); If the callback function is provided then gnutls will call it, in the handshake, just after the certificate message has been received. To verify or obtain the certificate the @code{gnutls_certificate_verify_peers2()} , @code{gnutls_certificate_type_get()} , @code{gnutls_certificate_get_peers()} functions can be used. The callback function should return 0 for the handshake to continue or non-zero to terminate. @strong{Since:} 3.4.6 @end deftypefun