/* 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 <sys/types.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <unistd.h>

#include <assert.h>

#include <gnutls/gnutls.h>

/* A very basic TLS client, with PSK authentication.

 */

#define CHECK(x) assert((x)>=0)

#define LOOP_CHECK(rval, cmd) \

        do { \

                rval = cmd; \

        } while(rval == GNUTLS_E_AGAIN || rval == GNUTLS_E_INTERRUPTED); \

        assert(rval >= 0)

#define MAX_BUF 1024

#define MSG "GET / HTTP/1.0\r\n\r\n"

extern int tcp_connect(void);

extern void tcp_close(int sd);

int main(void)

{

        int ret, sd, ii;

        gnutls_session_t session;

        char buffer[MAX_BUF + 1];

        const char *err;

        gnutls_psk_client_credentials_t pskcred;

        const gnutls_datum_t key = { (void *) "DEADBEEF", 8 };

        if (gnutls_check_version("3.6.3") == NULL) {

                fprintf(stderr, "GnuTLS 3.6.3 or later is required for this example\n");

                exit(1);

        }

        CHECK(gnutls_global_init());

        CHECK(gnutls_psk_allocate_client_credentials(&pskcred));

        CHECK(gnutls_psk_set_client_credentials(pskcred, "test", &key,

                                                GNUTLS_PSK_KEY_HEX));

        /* Initialize TLS session

         */

        CHECK(gnutls_init(&session, GNUTLS_CLIENT));

        ret =

            gnutls_set_default_priority_append(session,

                                         "-KX-ALL:+ECDHE-PSK:+DHE-PSK:+PSK",

                                         &err, 0);

        /* Alternative for pre-3.6.3 versions:

         * gnutls_priority_set_direct(session, "NORMAL:+ECDHE-PSK:+DHE-PSK:+PSK", &err)

         */

        if (ret < 0) {

                if (ret == GNUTLS_E_INVALID_REQUEST) {

                        fprintf(stderr, "Syntax error at: %s\n", err);

                }

                exit(1);

        }

        /* put the x509 credentials to the current session

         */

        CHECK(gnutls_credentials_set(session, GNUTLS_CRD_PSK, pskcred));

        /* connect to the peer

         */

        sd = tcp_connect();

        gnutls_transport_set_int(session, sd);

        gnutls_handshake_set_timeout(session,

                                     GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

        /* Perform the TLS handshake

         */

        do {

                ret = gnutls_handshake(session);

        }

        while (ret < 0 && gnutls_error_is_fatal(ret) == 0);

        if (ret < 0) {

                fprintf(stderr, "*** Handshake failed\n");

                gnutls_perror(ret);

                goto end;

        } else {

                char *desc;

                desc = gnutls_session_get_desc(session);

                printf("- Session info: %s\n", desc);

                gnutls_free(desc);

        }

        LOOP_CHECK(ret, gnutls_record_send(session, MSG, strlen(MSG)));

        LOOP_CHECK(ret, gnutls_record_recv(session, buffer, MAX_BUF));

        if (ret == 0) {

                printf("- Peer has closed the TLS connection\n");

                goto end;

        } else if (ret < 0 && gnutls_error_is_fatal(ret) == 0) {

                fprintf(stderr, "*** Warning: %s\n", gnutls_strerror(ret));

        } else if (ret < 0) {

                fprintf(stderr, "*** Error: %s\n", gnutls_strerror(ret));

                goto end;

        }

        if (ret > 0) {

                printf("- Received %d bytes: ", ret);

                for (ii = 0; ii < ret; ii++) {

                        fputc(buffer[ii], stdout);

                }

                fputs("\n", stdout);

        }

        CHECK(gnutls_bye(session, GNUTLS_SHUT_RDWR));

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_psk_free_client_credentials(pskcred);

        gnutls_global_deinit();

        return 0;

}