doc/examples/ex-client-anon.c

   1 /* This example code is placed in the public domain. */
   2
   3 #ifdef HAVE_CONFIG_H
   4 #include <config.h>
   5 #endif
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <sys/types.h>
  11 #include <sys/socket.h>
  12 #include <arpa/inet.h>
  13 #include <unistd.h>
  14 #include <gnutls/gnutls.h>
  15
  16 /* A very basic TLS client, with anonymous authentication.
  17  */
  18
  19 #define MAX_BUF 1024
  20 #define MSG "GET / HTTP/1.0\r\n\r\n"
  21
  22 extern int tcp_connect (void);
  23 extern void tcp_close (int sd);
  24
  25 int
  26 main (void)
  27 {
  28   int ret, sd, ii;
  29   gnutls_session_t session;
  30   char buffer[MAX_BUF + 1];
  31   gnutls_anon_client_credentials_t anoncred;
  32   /* Need to enable anonymous KX specifically. */
  33
  34   gnutls_global_init ();
  35
  36   gnutls_anon_allocate_client_credentials (&anoncred);
  37
  38   /* Initialize TLS session
  39    */
  40   gnutls_init (&session, GNUTLS_CLIENT);
  41
  42   /* Use default priorities */
  43   gnutls_priority_set_direct (session, "PERFORMANCE:+ANON-ECDH:+ANON-DH",
  44                               NULL);
  45
  46   /* put the anonymous credentials to the current session
  47    */
  48   gnutls_credentials_set (session, GNUTLS_CRD_ANON, anoncred);
  49
  50   /* connect to the peer
  51    */
  52   sd = tcp_connect ();
  53
  54   gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);
  55   gnutls_handshake_set_timeout (session, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
  56
  57   /* Perform the TLS handshake
  58    */
  59   do
  60     {
  61       ret = gnutls_handshake (session);
  62     }
  63   while (ret < 0 && gnutls_error_is_fatal (ret) == 0);
  64
  65   if (ret < 0)
  66     {
  67       fprintf (stderr, "*** Handshake failed\n");
  68       gnutls_perror (ret);
  69       goto end;
  70     }
  71   else
  72     {
  73       printf ("- Handshake was completed\n");
  74     }
  75
  76   gnutls_record_send (session, MSG, strlen (MSG));
  77
  78   ret = gnutls_record_recv (session, buffer, MAX_BUF);
  79   if (ret == 0)
  80     {
  81       printf ("- Peer has closed the TLS connection\n");
  82       goto end;
  83     }
  84   else if (ret < 0)
  85     {
  86       fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
  87       goto end;
  88     }
  89
  90   printf ("- Received %d bytes: ", ret);
  91   for (ii = 0; ii < ret; ii++)
  92     {
  93       fputc (buffer[ii], stdout);
  94     }
  95   fputs ("\n", stdout);
  96
  97   gnutls_bye (session, GNUTLS_SHUT_RDWR);
  98
  99 end:
 100
 101   tcp_close (sd);
 102
 103   gnutls_deinit (session);
 104
 105   gnutls_anon_free_client_credentials (anoncred);
 106
 107   gnutls_global_deinit ();
 108
 109   return 0;
 110 }