7.5.2 Example client with X.509 certificate authentication and TOFU

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

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

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/xssl.h>
#include "examples.h"

/* A simple TLS client, with X.509 authentication. Certificate verification
 * with a fixed CA, and trust on first use. 
 */

extern int tcp_connect(void);
extern void tcp_close(int sd);

int main(void)
{
        int ret;
        char *line = NULL;
        size_t line_len;
        xssl_cred_t cred;
        xssl_t sb;
        gnutls_cinput_st aux[2];
        unsigned aux_size = 0;
        unsigned int status;
        int fd;

        gnutls_global_init();

        fd = tcp_connect();

        aux[aux_size].type = GNUTLS_CINPUT_TYPE_FILE;
        aux[aux_size].contents = GNUTLS_CINPUT_CAS;
        aux[aux_size].fmt = GNUTLS_X509_FMT_PEM;
        aux[aux_size].i1.file = "/path/to/ca/file";
        aux_size++;

        /* This may be skipped to use the default DB file */
        aux[aux_size].type = GNUTLS_CINPUT_TYPE_FILE;
        aux[aux_size].contents = GNUTLS_CINPUT_TOFU_DB;
        aux[aux_size].i1.file = "/path/to/trust/db/file";
        aux_size++;

        ret =
            xssl_cred_init(&cred,
                           GNUTLS_VMETHOD_GIVEN_CAS | GNUTLS_VMETHOD_TOFU,
                           aux, aux_size);
        if (ret < 0)
                exit(1);

        /* Initialize TLS session
         */
        ret = xssl_client_init(&sb, "www.example.com", NULL,
                               (gnutls_transport_ptr_t) fd,
                               NULL, cred, &status, 0);
        if (ret < 0) {
                if (ret == GNUTLS_E_AUTH_ERROR) {
                        gnutls_datum_t txt;

                        gnutls_certificate_verification_status_print
                            (status, GNUTLS_CRT_X509, &txt, 0);

                        fprintf(stderr, "Verification error (%x): %s\n",
                                status, txt.data);
                        gnutls_free(txt.data);
                }
                exit(1);
        }
#define REQ "GET / HTTP/1.0\r\n"
        ret = xssl_write(sb, REQ, sizeof(REQ) - 1);
        if (ret < 0)
                exit(1);

        do {
                ret = xssl_getline(sb, &line, &line_len);
                if (ret < 0)
                        exit(1);

                fprintf(stderr, "received: %s\n", line);
        }
        while (ret >= 0);

        gnutls_free(line);

        xssl_deinit(sb);

        tcp_close(fd);

        xssl_cred_deinit(cred);

        gnutls_global_deinit();

        return 0;
}

This document was generated on February 9, 2014 using texi2html 5.0.