doc/tex/ex2.tex

   1 \begin{verbatim}
   2
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <sys/types.h>
   6 #include <sys/socket.h>
   7 #include <netinet/in.h>
   8 #include <arpa/inet.h>
   9 #include <gnutls.h>
  10
  11 #define MAX_BUF 1024
  12 #define CRLFILE "crl.pem"
  13 #define CAFILE "ca.pem"
  14 #define SA struct sockaddr
  15 #define MSG "GET / HTTP/1.0\r\n\r\n"
  16
  17 int main()
  18 {
  19    const char *PORT = "443";
  20    const char *SERVER = "127.0.0.1";
  21    int err, ret;
  22    int sd, ii;
  23    struct sockaddr_in sa;
  24    GNUTLS_STATE state;
  25    char buffer[MAX_BUF + 1];
  26    GNUTLS_CERTIFICATE_CLIENT_CREDENTIALS xcred;
  27    const int protocol_priority[] = { GNUTLS_TLS1, GNUTLS_SSL3, 0 };
  28    const int kx_priority[] = { GNUTLS_KX_RSA, 0 };
  29    const int cipher_priority[] = { GNUTLS_CIPHER_3DES_CBC, GNUTLS_CIPHER_ARCFOUR, 0};
  30    const int comp_priority[] = { GNUTLS_COMP_ZLIB, GNUTLS_COMP_NULL, 0 };
  31    const int mac_priority[] = { GNUTLS_MAC_SHA, GNUTLS_MAC_MD5, 0 };
  32
  33
  34    if (gnutls_global_init() < 0) {
  35       fprintf(stderr, "global state initialization error\n");
  36       exit(1);
  37    }
  38    /* X509 stuff */
  39    if (gnutls_certificate_allocate_client_sc(&xcred) < 0) {
  40       fprintf(stderr, "memory error\n");
  41       exit(1);
  42    }
  43    /* set's the trusted cas file
  44     */
  45    gnutls_certificate_set_x509_trust_file(xcred, CAFILE, CRLFILE, GNUTLS_X509_FMT_PEM);
  46
  47    /* connects to server
  48     */
  49    sd = socket(AF_INET, SOCK_STREAM, 0);
  50
  51    memset(&sa, '\0', sizeof(sa));
  52    sa.sin_family = AF_INET;
  53    sa.sin_port = htons(atoi(PORT));
  54    inet_pton(AF_INET, SERVER, &sa.sin_addr);
  55
  56    err = connect(sd, (SA *) & sa, sizeof(sa));
  57    if (err < 0) {
  58       fprintf(stderr, "Connect error\n");
  59       exit(1);
  60    }
  61    /* Initialize TLS state
  62     */
  63    gnutls_init(&state, GNUTLS_CLIENT);
  64
  65    /* allow both SSL3 and TLS1
  66     */
  67    gnutls_protocol_set_priority(state, protocol_priority);
  68
  69    /* allow only ARCFOUR and 3DES ciphers
  70     * (3DES has the highest priority)
  71     */
  72    gnutls_cipher_set_priority(state, cipher_priority);
  73
  74    /* only allow null compression
  75     */
  76    gnutls_compression_set_priority(state, comp_priority);
  77
  78    /* use GNUTLS_KX_RSA
  79     */
  80    gnutls_kx_set_priority(state, kx_priority);
  81
  82    /* allow the usage of both SHA and MD5
  83     */
  84    gnutls_mac_set_priority(state, mac_priority);
  85
  86
  87    /* put the x509 credentials to the current state
  88     */
  89    gnutls_cred_set(state, GNUTLS_CRD_CERTIFICATE, xcred);
  90
  91
  92    gnutls_transport_set_ptr( state, sd);
  93    /* Perform the TLS handshake
  94     */
  95    ret = gnutls_handshake( state);
  96
  97    if (ret < 0) {
  98       fprintf(stderr, "*** Handshake failed\n");
  99       gnutls_perror(ret);
 100       goto end;
 101    } else {
 102       printf("- Handshake was completed\n");
 103    }
 104
 105    gnutls_record_send( state, MSG, strlen(MSG));
 106
 107    ret = gnutls_record_recv( state, buffer, MAX_BUF);
 108    if (gnutls_error_is_fatal(ret) == 1 || ret == 0) {
 109       if (ret == 0) {
 110          printf("- Peer has closed the GNUTLS connection\n");
 111          goto end;
 112       } else {
 113          fprintf(stderr, "*** Received corrupted data(%d) - server has terminated the connection abnormally\n",
 114                  ret);
 115          goto end;
 116       }
 117    } else {
 118       if (ret == GNUTLS_E_WARNING_ALERT_RECEIVED || ret == GNUTLS_E_FATAL_ALERT_RECEIVED)
 119          printf("* Received alert [%d]\n", gnutls_alert_get(state));
 120       if (ret == GNUTLS_E_REHANDSHAKE)
 121          printf("* Received HelloRequest message (server asked to rehandshake)\n");
 122          gnutls_alert_send_appropriate( state, ret); /* we don't want rehandshake */
 123    }
 124
 125    if (ret > 0) {
 126       printf("- Received %d bytes: ", ret);
 127       for (ii = 0; ii < ret; ii++) {
 128          fputc(buffer[ii], stdout);
 129       }
 130       fputs("\n", stdout);
 131    }
 132    gnutls_bye( state, GNUTLS_SHUT_RDWR);
 133
 134  end:
 135
 136    shutdown(sd, SHUT_RDWR);     /* no more receptions */
 137    close(sd);
 138
 139    gnutls_deinit(state);
 140
 141    gnutls_certificate_free_client_sc(xcred);
 142
 143    gnutls_global_deinit();
 144
 145    return 0;
 146 }
 147
 148 \end{verbatim}