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

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <string.h>

#include <unistd.h>

#include <gnutls/gnutls.h>

#include <assert.h>

#define KEYFILE "key.pem"

#define CERTFILE "cert.pem"

#define CAFILE "/etc/ssl/certs/ca-certificates.crt"

#define CRLFILE "crl.pem"

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

#define LOOP_CHECK(rval, cmd) \

        do { \

                rval = cmd; \

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

/* The OCSP status file contains up to date information about revocation

 * of the server's certificate. That can be periodically be updated

 * using:

 * $ ocsptool --ask --load-cert your_cert.pem --load-issuer your_issuer.pem

 *            --load-signer your_issuer.pem --outfile ocsp-status.der

 */

#define OCSP_STATUS_FILE "ocsp-status.der"

/* This is a sample TLS 1.0 echo server, using X.509 authentication and

 * OCSP stapling support.

 */

#define MAX_BUF 1024

#define PORT 5556               /* listen to 5556 port */

int main(void)

{

        int listen_sd;

        int sd, ret;

        gnutls_certificate_credentials_t x509_cred;

        gnutls_priority_t priority_cache;

        struct sockaddr_in sa_serv;

        struct sockaddr_in sa_cli;

        socklen_t client_len;

        char topbuf[512];

        gnutls_session_t session;

        char buffer[MAX_BUF + 1];

        int optval = 1;

        /* for backwards compatibility with gnutls < 3.3.0 */

        CHECK(gnutls_global_init());

        CHECK(gnutls_certificate_allocate_credentials(&x509_cred));

        CHECK(gnutls_certificate_set_x509_trust_file(x509_cred, CAFILE,

                                                     GNUTLS_X509_FMT_PEM));

        CHECK(gnutls_certificate_set_x509_crl_file(x509_cred, CRLFILE,

                                                   GNUTLS_X509_FMT_PEM));

        /* The following code sets the certificate key pair as well as, 

         * an OCSP response which corresponds to it. It is possible

         * to set multiple key-pairs and multiple OCSP status responses

         * (the latter since 3.5.6). See the manual pages of the individual

         * functions for more information.

         */

        CHECK(gnutls_certificate_set_x509_key_file(x509_cred, CERTFILE,

                                                   KEYFILE,

                                                   GNUTLS_X509_FMT_PEM));

        CHECK(gnutls_certificate_set_ocsp_status_request_file(x509_cred,

                                                              OCSP_STATUS_FILE,

                                                              0));

        CHECK(gnutls_priority_init(&priority_cache, NULL, NULL));

        /* Instead of the default options as shown above one could specify

         * additional options such as server precedence in ciphersuite selection

         * as follows:

         * gnutls_priority_init2(&priority_cache,

         *                       "%SERVER_PRECEDENCE",

         *                       NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND);

	 */

#if GNUTLS_VERSION_NUMBER >= 0x030506

        /* only available since GnuTLS 3.5.6, on previous versions see

         * gnutls_certificate_set_dh_params(). */

        gnutls_certificate_set_known_dh_params(x509_cred, GNUTLS_SEC_PARAM_MEDIUM);

#endif

        /* Socket operations

         */

        listen_sd = socket(AF_INET, SOCK_STREAM, 0);

        memset(&sa_serv, '\0', sizeof(sa_serv));

        sa_serv.sin_family = AF_INET;

        sa_serv.sin_addr.s_addr = INADDR_ANY;

        sa_serv.sin_port = htons(PORT); /* Server Port number */

        setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,

                   sizeof(int));

        bind(listen_sd, (struct sockaddr *) &sa_serv, sizeof(sa_serv));

        listen(listen_sd, 1024);

        printf("Server ready. Listening to port '%d'.\n\n", PORT);

        client_len = sizeof(sa_cli);

        for (;;) {

                CHECK(gnutls_init(&session, GNUTLS_SERVER));

                CHECK(gnutls_priority_set(session, priority_cache));

                CHECK(gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,

                                             x509_cred));

                /* We don't request any certificate from the client.

                 * If we did we would need to verify it. One way of

                 * doing that is shown in the "Verifying a certificate"

                 * example.

                 */

                gnutls_certificate_server_set_request(session,

                                                      GNUTLS_CERT_IGNORE);

                gnutls_handshake_set_timeout(session,

                                             GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

                sd = accept(listen_sd, (struct sockaddr *) &sa_cli,

                            &client_len);

                printf("- connection from %s, port %d\n",

                       inet_ntop(AF_INET, &sa_cli.sin_addr, topbuf,

                                 sizeof(topbuf)), ntohs(sa_cli.sin_port));

                gnutls_transport_set_int(session, sd);

                LOOP_CHECK(ret, gnutls_handshake(session));

                if (ret < 0) {

                        close(sd);

                        gnutls_deinit(session);

                        fprintf(stderr,

                                "*** Handshake has failed (%s)\n\n",

                                gnutls_strerror(ret));

                        continue;

                }

                printf("- Handshake was completed\n");

                /* see the Getting peer's information example */

                /* print_info(session); */

                for (;;) {

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

                        if (ret == 0) {

                                printf

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

                                break;

                        } else if (ret < 0

                                   && gnutls_error_is_fatal(ret) == 0) {

                                fprintf(stderr, "*** Warning: %s\n",

                                        gnutls_strerror(ret));

                        } else if (ret < 0) {

                                fprintf(stderr, "\n*** Received corrupted "

                                        "data(%d). Closing the connection.\n\n",

                                        ret);

                                break;

                        } else if (ret > 0) {

                                /* echo data back to the client

                                 */

                                CHECK(gnutls_record_send(session, buffer, ret));

                        }

                }

                printf("\n");

                /* do not wait for the peer to close the connection.

                 */

                LOOP_CHECK(ret, gnutls_bye(session, GNUTLS_SHUT_WR));

                close(sd);

                gnutls_deinit(session);

        }

        close(listen_sd);

        gnutls_certificate_free_credentials(x509_cred);

        gnutls_priority_deinit(priority_cache);

        gnutls_global_deinit();

        return 0;

}