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/* 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;
}
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