7.5.1 Checking for an Alert

This is a function that checks if an alert has been received in the current session.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>

#include "examples.h"

/* This function will check whether the given return code from
 * a gnutls function (recv/send), is an alert, and will print
 * that alert.
 */
void
check_alert (gnutls_session_t session, int ret)
{
  int last_alert;

  if (ret == GNUTLS_E_WARNING_ALERT_RECEIVED
      || ret == GNUTLS_E_FATAL_ALERT_RECEIVED)
    {
      last_alert = gnutls_alert_get (session);

      /* The check for renegotiation is only useful if we are 
       * a server, and we had requested a rehandshake.
       */
      if (last_alert == GNUTLS_A_NO_RENEGOTIATION &&
	  ret == GNUTLS_E_WARNING_ALERT_RECEIVED)
	printf ("* Received NO_RENEGOTIATION alert. "
		"Client Does not support renegotiation.\n");
      else
	printf ("* Received alert '%d': %s.\n", last_alert,
		gnutls_alert_get_name (last_alert));
    }
}