doc/examples/ex-client-resume.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 <string.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <gnutls/gnutls.h>
  11
  12 /* Those functions are defined in other examples.
  13  */
  14 extern void check_alert (gnutls_session_t session, int ret);
  15 extern int tcp_connect (void);
  16 extern void tcp_close (int sd);
  17
  18 #define MAX_BUF 1024
  19 #define CAFILE "/etc/ssl/certs/ca-certificates.crt"
  20 #define MSG "GET / HTTP/1.0\r\n\r\n"
  21
  22 int
  23 main (void)
  24 {
  25   int ret;
  26   int sd, ii;
  27   gnutls_session_t session;
  28   char buffer[MAX_BUF + 1];
  29   gnutls_certificate_credentials_t xcred;
  30
  31   /* variables used in session resuming
  32    */
  33   int t;
  34   char *session_data = NULL;
  35   size_t session_data_size = 0;
  36
  37   gnutls_global_init ();
  38
  39   /* X509 stuff */
  40   gnutls_certificate_allocate_credentials (&xcred);
  41
  42   gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);
  43
  44   for (t = 0; t < 2; t++)
  45     {                           /* connect 2 times to the server */
  46
  47       sd = tcp_connect ();
  48
  49       gnutls_init (&session, GNUTLS_CLIENT);
  50
  51       gnutls_priority_set_direct (session, "PERFORMANCE:!ARCFOUR-128", NULL);
  52
  53       gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);
  54
  55       if (t > 0)
  56         {
  57           /* if this is not the first time we connect */
  58           gnutls_session_set_data (session, session_data, session_data_size);
  59           free (session_data);
  60         }
  61
  62       gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);
  63       gnutls_handshake_set_timeout (session, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
  64
  65       /* Perform the TLS handshake
  66        */
  67       do
  68         {
  69           ret = gnutls_handshake (session);
  70         }
  71       while (ret < 0 && gnutls_error_is_fatal (ret) == 0);
  72
  73       if (ret < 0)
  74         {
  75           fprintf (stderr, "*** Handshake failed\n");
  76           gnutls_perror (ret);
  77           goto end;
  78         }
  79       else
  80         {
  81           printf ("- Handshake was completed\n");
  82         }
  83
  84       if (t == 0)
  85         {                       /* the first time we connect */
  86           /* get the session data size */
  87           gnutls_session_get_data (session, NULL, &session_data_size);
  88           session_data = malloc (session_data_size);
  89
  90           /* put session data to the session variable */
  91           gnutls_session_get_data (session, session_data, &session_data_size);
  92
  93         }
  94       else
  95         {                       /* the second time we connect */
  96
  97           /* check if we actually resumed the previous session */
  98           if (gnutls_session_is_resumed (session) != 0)
  99             {
 100               printf ("- Previous session was resumed\n");
 101             }
 102           else
 103             {
 104               fprintf (stderr, "*** Previous session was NOT resumed\n");
 105             }
 106         }
 107
 108       /* This function was defined in a previous example
 109        */
 110       /* print_info(session); */
 111
 112       gnutls_record_send (session, MSG, strlen (MSG));
 113
 114       ret = gnutls_record_recv (session, buffer, MAX_BUF);
 115       if (ret == 0)
 116         {
 117           printf ("- Peer has closed the TLS connection\n");
 118           goto end;
 119         }
 120       else if (ret < 0)
 121         {
 122           fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
 123           goto end;
 124         }
 125
 126       printf ("- Received %d bytes: ", ret);
 127       for (ii = 0; ii < ret; ii++)
 128         {
 129           fputc (buffer[ii], stdout);
 130         }
 131       fputs ("\n", stdout);
 132
 133       gnutls_bye (session, GNUTLS_SHUT_RDWR);
 134
 135     end:
 136
 137       tcp_close (sd);
 138
 139       gnutls_deinit (session);
 140
 141     }                           /* for() */
 142
 143   gnutls_certificate_free_credentials (xcred);
 144
 145   gnutls_global_deinit ();
 146
 147   return 0;
 148 }