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
  64       /* Perform the TLS handshake
  65        */
  66       do
  67         {
  68           ret = gnutls_handshake (session);
  69         }
  70       while (ret < 0 && gnutls_error_is_fatal (ret) == 0);
  71
  72       if (ret < 0)
  73         {
  74           fprintf (stderr, "*** Handshake failed\n");
  75           gnutls_perror (ret);
  76           goto end;
  77         }
  78       else
  79         {
  80           printf ("- Handshake was completed\n");
  81         }
  82
  83       if (t == 0)
  84         {                       /* the first time we connect */
  85           /* get the session data size */
  86           gnutls_session_get_data (session, NULL, &session_data_size);
  87           session_data = malloc (session_data_size);
  88
  89           /* put session data to the session variable */
  90           gnutls_session_get_data (session, session_data, &session_data_size);
  91
  92         }
  93       else
  94         {                       /* the second time we connect */
  95
  96           /* check if we actually resumed the previous session */
  97           if (gnutls_session_is_resumed (session) != 0)
  98             {
  99               printf ("- Previous session was resumed\n");
 100             }
 101           else
 102             {
 103               fprintf (stderr, "*** Previous session was NOT resumed\n");
 104             }
 105         }
 106
 107       /* This function was defined in a previous example
 108        */
 109       /* print_info(session); */
 110
 111       gnutls_record_send (session, MSG, strlen (MSG));
 112
 113       ret = gnutls_record_recv (session, buffer, MAX_BUF);
 114       if (ret == 0)
 115         {
 116           printf ("- Peer has closed the TLS connection\n");
 117           goto end;
 118         }
 119       else if (ret < 0)
 120         {
 121           fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
 122           goto end;
 123         }
 124
 125       printf ("- Received %d bytes: ", ret);
 126       for (ii = 0; ii < ret; ii++)
 127         {
 128           fputc (buffer[ii], stdout);
 129         }
 130       fputs ("\n", stdout);
 131
 132       gnutls_bye (session, GNUTLS_SHUT_RDWR);
 133
 134     end:
 135
 136       tcp_close (sd);
 137
 138       gnutls_deinit (session);
 139
 140     }                           /* for() */
 141
 142   gnutls_certificate_free_credentials (xcred);
 143
 144   gnutls_global_deinit ();
 145
 146   return 0;
 147 }