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<title>GnuTLS 3.5.3: Echo server with X.509 authentication</title>
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<a name="Echo-server-with-X_002e509-authentication"></a>
<div class="header">
<p>
Next: <a href="Echo-server-with-SRP-authentication.html#Echo-server-with-SRP-authentication" accesskey="n" rel="next">Echo server with SRP authentication</a>, Up: <a href="Server-examples.html#Server-examples" accesskey="u" rel="up">Server examples</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Echo-server-with-X_002e509-authentication-1"></a>
<h4 class="subsection">7.2.1 Echo server with <acronym>X.509</acronym> authentication</h4>
<p>This example is a very simple echo server which supports
<acronym>X.509</acronym> authentication.
</p>
<pre class="verbatim">/* 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)
/* 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 */
/* These are global */
static gnutls_dh_params_t dh_params;
static int generate_dh_params(void)
{
unsigned int bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
GNUTLS_SEC_PARAM_MEDIUM);
/* Generate Diffie-Hellman parameters - for use with DHE
* kx algorithms. When short bit length is used, it might
* be wise to regenerate parameters often.
*/
CHECK(gnutls_dh_params_init(&dh_params));
CHECK(gnutls_dh_params_generate2(dh_params, bits));
return 0;
}
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));
CHECK(gnutls_certificate_set_x509_key_file(x509_cred, CERTFILE,
KEYFILE,
GNUTLS_X509_FMT_PEM));
/* loads an OCSP status request if available */
CHECK(gnutls_certificate_set_ocsp_status_request_file(x509_cred,
OCSP_STATUS_FILE,
0));
generate_dh_params();
CHECK(gnutls_priority_init(&priority_cache,
"PERFORMANCE:%SERVER_PRECEDENCE", NULL));
gnutls_certificate_set_dh_params(x509_cred, dh_params);
/* 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);
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);
do {
ret = gnutls_handshake(session);
}
while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
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 (;;) {
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.
*/
CHECK(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;
}
</pre>
<hr>
<div class="header">
<p>
Next: <a href="Echo-server-with-SRP-authentication.html#Echo-server-with-SRP-authentication" accesskey="n" rel="next">Echo server with SRP authentication</a>, Up: <a href="Server-examples.html#Server-examples" accesskey="u" rel="up">Server examples</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
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