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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
/* A very basic TLS client, with X.509 authentication.
*/
#define MAX_BUF 1024
#define CAFILE "ca.pem"
#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];
gnutls_certificate_credentials_t xcred;
/* Allow connections to servers that have OpenPGP keys as well.
*/
const int cert_type_priority[3] = { GNUTLS_CRT_X509,
GNUTLS_CRT_OPENPGP, 0
};
gnutls_global_init ();
/* X509 stuff */
gnutls_certificate_allocate_credentials (&xcred);
/* sets the trusted cas file
*/
gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);
/* Initialize TLS session
*/
gnutls_init (&session, GNUTLS_CLIENT);
/* Use default priorities */
gnutls_set_default_priority (session);
gnutls_certificate_type_set_priority (session, cert_type_priority);
/* put the x509 credentials to the current session
*/
gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);
/* connect to the peer
*/
sd = tcp_connect ();
gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);
/* Perform the TLS handshake
*/
ret = gnutls_handshake (session);
if (ret < 0)
{
fprintf (stderr, "*** Handshake failed\n");
gnutls_perror (ret);
goto end;
}
else
{
printf ("- Handshake was completed\n");
}
gnutls_record_send (session, MSG, strlen (MSG));
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)
{
fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
goto end;
}
printf ("- Received %d bytes: ", ret);
for (ii = 0; ii < ret; ii++)
{
fputc (buffer[ii], stdout);
}
fputs ("\n", stdout);
gnutls_bye (session, GNUTLS_SHUT_RDWR);
end:
tcp_close (sd);
gnutls_deinit (session);
gnutls_certificate_free_credentials (xcred);
gnutls_global_deinit ();
return 0;
}
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