4 * Copyright (C) 2011 Simon Ruderich
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #include "connection.h"
34 /* Maximum line of a HTTP request line. Longer request lines are aborted with
35 * an error. The standard doesn't specify a maximum line length but this
36 * should be a good limit to make processing simpler. */
37 #define MAX_REQUEST_LINE 4096
40 static int initialize_tls_session_client(int peer_socket,
42 gnutls_session_t *session,
43 gnutls_certificate_credentials_t *x509_cred);
44 static int initialize_tls_session_server(int peer_socket,
45 gnutls_session_t *session,
46 gnutls_certificate_credentials_t *x509_cred);
48 static int read_http_request(FILE *client_fd, char *request, size_t length);
49 static void send_bad_request(FILE *client_fd);
50 static void send_forwarding_failure(FILE *client_fd);
51 static void tls_send_invalid_cert_message(gnutls_session_t session);
54 static void transfer_data(int client, int server);
55 static int read_from_write_to(int from, int to);
57 static void transfer_data_tls(int client, int server,
58 gnutls_session_t client_session,
59 gnutls_session_t server_session);
60 static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to);
62 static int connect_to_host(const char *hostname, const char *port);
64 static int parse_request(const char *buffer, char *host, char *port,
68 void handle_connection(int client_socket) {
70 FILE *client_fd, *server_fd;
72 char buffer[MAX_REQUEST_LINE];
73 char host[MAX_REQUEST_LINE];
79 /* client_x509_cred is used when talking to the client (acting as a TSL
80 * server), server_x509_cred is used when talking to the server (acting as
82 gnutls_certificate_credentials_t client_x509_cred, server_x509_cred;
84 gnutls_session_t client_session, server_session;
85 /* initialize_tls_session_*() called? - used for goto out */
86 int client_session_init, server_session_init;
87 /* gnutls_handshake() called? - used for goto out */
88 int client_session_started, server_session_started;
89 /* Validation failed? If yes we need to send the special "invalid"
91 int validation_failed;
93 LOG(LOG_DEBUG, "new connection");
98 client_session_init = 0;
99 server_session_init = 0;
100 client_session_started = 0;
101 server_session_started = 0;
102 validation_failed = 0;
104 client_fd = fdopen(client_socket, "a+");
105 if (NULL == client_fd) {
106 LOG_PERROR(LOG_WARNING, "fdopen(): client failed");
110 /* Read request line (CONNECT ..) and headers (they are discarded). */
111 result = read_http_request(client_fd, buffer, sizeof(buffer));
114 LOG(LOG_WARNING, "read_http_request(): client read error");
116 } else if (-2 == result) {
118 LOG(LOG_WARNING, "read_http_request(): client EOF");
119 send_bad_request(client_fd);
123 if (0 != parse_request(buffer, host, port, &version_minor)) {
124 LOG(LOG_WARNING, "bad request: %s", buffer);
125 send_bad_request(client_fd);
129 LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
131 /* Connect to proxy server or directly to server. */
132 if (NULL != global_proxy_host && NULL != global_proxy_port) {
133 LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host,
135 server_socket = connect_to_host(global_proxy_host, global_proxy_port);
137 LOG(LOG_DEBUG, "connecting to %s:%s", host, port);
138 server_socket = connect_to_host(host, port);
141 if (-1 == server_socket) {
142 LOG(LOG_WARNING, "failed to connect to server");
143 send_forwarding_failure(client_fd);
146 server_fd = fdopen(server_socket, "a+");
147 if (NULL == server_fd) {
148 LOG_PERROR(LOG_WARNING, "fdopen(): server failed");
149 send_forwarding_failure(client_fd);
153 /* Connect to proxy if requested (command line option). */
154 if (NULL != global_proxy_host && NULL != global_proxy_port) {
155 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
156 fprintf(server_fd, "\r\n");
158 /* Read response line from proxy server. */
159 result = read_http_request(server_fd, buffer, sizeof(buffer));
162 LOG(LOG_WARNING, "read_http_request(): proxy read error");
163 send_forwarding_failure(client_fd);
165 } else if (-2 == result) {
167 LOG(LOG_WARNING, "read_http_request(): proxy EOF");
168 send_forwarding_failure(client_fd);
172 /* Check response of proxy server. */
173 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
174 LOG(LOG_WARNING, "bad proxy response: %s", buffer);
175 send_forwarding_failure(client_fd);
180 LOG(LOG_DEBUG, "connection to server established");
182 result = initialize_tls_session_server(server_socket, &server_session,
184 /* Initialize TLS client credentials to talk to the server. */
186 LOG(LOG_WARNING, "initialize_tls_session_server() failed");
187 send_forwarding_failure(client_fd);
190 server_session_init = 1;
192 LOG(LOG_DEBUG, "starting server TLS handshake");
194 /* Try to establish TLS handshake between us and server. */
195 result = gnutls_handshake(server_session);
196 if (GNUTLS_E_SUCCESS != result) {
197 LOG(LOG_WARNING, "server TLS handshake failed: %s",
198 gnutls_strerror(result));
199 send_forwarding_failure(client_fd);
202 server_session_started = 1;
204 LOG(LOG_DEBUG, "server TLS handshake finished");
206 /* Make sure the server certificate is valid and known. */
207 if (0 != verify_tls_connection(server_session, host)) {
208 LOG(LOG_ERROR, "server certificate validation failed!");
209 /* We send the error message over our TLS connection to the client,
210 * but with an invalid certificate. */
211 validation_failed = 1;
214 /* Initialize TLS server credentials to talk to the client. */
215 result = initialize_tls_session_client(client_socket,
216 /* use special host if the server
217 * certificate was invalid */
218 (validation_failed) ? "invalid"
223 LOG(LOG_WARNING, "initialize_tls_session_client() failed");
224 send_forwarding_failure(client_fd);
227 client_session_init = 1;
229 /* We've established a connection, tell the client. */
230 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
231 fprintf(client_fd, "\r\n");
234 LOG(LOG_DEBUG, "starting client TLS handshake");
236 /* Try to establish TLS handshake between client and us. */
237 result = gnutls_handshake(client_session);
238 if (GNUTLS_E_SUCCESS != result) {
239 LOG(LOG_WARNING, "client TLS handshake failed: %s",
240 gnutls_strerror(result));
241 send_forwarding_failure(client_fd);
244 client_session_started = 1;
246 LOG(LOG_DEBUG, "client TLS handshake finished");
248 /* Tell the client that the verification failed. Shouldn't be necessary as
249 * the client should terminate the connection because he received the
250 * invalid certificate but better be sure. */
251 if (validation_failed) {
252 tls_send_invalid_cert_message(client_session);
256 LOG(LOG_DEBUG, "transferring data");
258 /* Proxy data between client and server until one suite is done (EOF or
260 transfer_data_tls(client_socket, server_socket,
261 client_session, server_session);
263 LOG(LOG_DEBUG, "finished transferring data");
266 /* Close TLS sessions if necessary. Use GNUTLS_SHUT_RDWR so the data is
267 * reliable transmitted. */
268 if (0 != server_session_started) {
269 gnutls_bye(server_session, GNUTLS_SHUT_RDWR);
271 if (0 != client_session_started) {
272 gnutls_bye(client_session, GNUTLS_SHUT_RDWR);
274 if (0 != server_session_init) {
275 gnutls_deinit(server_session);
276 gnutls_certificate_free_credentials(server_x509_cred);
278 if (0 != client_session_init) {
279 gnutls_deinit(client_session);
280 gnutls_certificate_free_cas(client_x509_cred);
281 gnutls_certificate_free_keys(client_x509_cred);
282 gnutls_certificate_free_credentials(client_x509_cred);
285 /* Close connection to server/proxy. */
286 if (NULL != server_fd) {
288 } else if (-1 != server_socket) {
289 close(server_socket);
291 LOG(LOG_DEBUG, "connection to server closed");
292 /* Close connection to client. */
293 if (NULL != client_fd) {
296 close(client_socket);
298 LOG(LOG_DEBUG, "connection to client closed");
300 LOG(LOG_DEBUG, "connection finished");
304 static int initialize_tls_session_client(int peer_socket,
305 const char *hostname,
306 gnutls_session_t *session,
307 gnutls_certificate_credentials_t *x509_cred) {
309 int use_invalid_cert;
312 /* The "invalid" hostname is special. If it's used we send an invalid
313 * certificate to let the client know something is wrong. */
314 use_invalid_cert = 0 == strcmp(hostname, "invalid");
316 /* Hostname too long. */
317 if (sizeof(path) - strlen(PROXY_SERVER_CERT_FORMAT) <= strlen(hostname)) {
319 "initialize_tls_session_client(): hostname too long: '%s'",
323 /* Try to prevent path traversals in hostnames. */
324 if (NULL != strstr(hostname, "..")) {
326 "initialize_tls_session_client(): possible path traversal: '%s'",
330 snprintf(path, sizeof(path), PROXY_SERVER_CERT_FORMAT, hostname);
332 result = gnutls_certificate_allocate_credentials(x509_cred);
333 if (GNUTLS_E_SUCCESS != result) {
335 "initialize_tls_session_client(): \
336 gnutls_certificate_allocate_credentials(): %s",
337 gnutls_strerror(result));
341 /* Load proxy CA file, this CA "list" is send to the client. */
342 if (!use_invalid_cert) {
343 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
345 GNUTLS_X509_FMT_PEM);
346 /* If the invalid hostname was specified do nothing, we use a self-signed
347 * certificate in this case. */
353 "initialize_tls_session_client(): can't read CA file: '%s'",
355 gnutls_certificate_free_credentials(*x509_cred);
358 /* And certificate for this website and proxy's private key. */
359 if (!use_invalid_cert) {
360 result = gnutls_certificate_set_x509_key_file(*x509_cred,
361 path, PROXY_KEY_FILE,
362 GNUTLS_X509_FMT_PEM);
363 /* If the invalid hostname was specified load our special "invalid"
366 result = gnutls_certificate_set_x509_key_file(*x509_cred,
367 PROXY_INVALID_CERT_FILE,
369 GNUTLS_X509_FMT_PEM);
371 if (GNUTLS_E_SUCCESS != result) {
373 "initialize_tls_session_client(): \
374 can't read server certificate ('%s') or key file ('%s'): %s",
375 path, PROXY_KEY_FILE, gnutls_strerror(result));
376 gnutls_certificate_free_credentials(*x509_cred);
377 /* Could be a missing certificate. */
381 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
383 result = gnutls_init(session, GNUTLS_SERVER);
384 if (GNUTLS_E_SUCCESS != result) {
386 "initialize_tls_session_client(): gnutls_init(): %s",
387 gnutls_strerror(result));
388 gnutls_certificate_free_credentials(*x509_cred);
391 result = gnutls_priority_set(*session, tls_priority_cache);
392 if (GNUTLS_E_SUCCESS != result) {
394 "initialize_tls_session_client(): gnutls_priority_set(): %s",
395 gnutls_strerror(result));
396 gnutls_deinit(*session);
397 gnutls_certificate_free_credentials(*x509_cred);
400 result = gnutls_credentials_set(*session,
401 GNUTLS_CRD_CERTIFICATE, *x509_cred);
402 if (GNUTLS_E_SUCCESS != result) {
404 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
405 gnutls_strerror(result));
406 gnutls_deinit(*session);
407 gnutls_certificate_free_credentials(*x509_cred);
411 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
415 static int initialize_tls_session_server(int peer_socket,
416 gnutls_session_t *session,
417 gnutls_certificate_credentials_t *x509_cred) {
420 result = gnutls_certificate_allocate_credentials(x509_cred);
421 if (GNUTLS_E_SUCCESS != result) {
423 "initialize_tls_session_server(): \
424 gnutls_certificate_allocate_credentials(): %s",
425 gnutls_strerror(result));
429 result = gnutls_init(session, GNUTLS_CLIENT);
430 if (GNUTLS_E_SUCCESS != result) {
432 "initialize_tls_session_server(): gnutls_init(): %s",
433 gnutls_strerror(result));
434 gnutls_certificate_free_credentials(*x509_cred);
437 gnutls_priority_set(*session, tls_priority_cache);
438 if (GNUTLS_E_SUCCESS != result) {
440 "initialize_tls_session_server(): gnutls_priority_set(): %s",
441 gnutls_strerror(result));
442 gnutls_deinit(*session);
443 gnutls_certificate_free_credentials(*x509_cred);
446 result = gnutls_credentials_set(*session,
447 GNUTLS_CRD_CERTIFICATE, *x509_cred);
448 if (GNUTLS_E_SUCCESS != result) {
450 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
451 gnutls_strerror(result));
452 gnutls_deinit(*session);
453 gnutls_certificate_free_credentials(*x509_cred);
457 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
463 /* Read HTTP request line and headers (ignored).
465 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
467 static int read_http_request(FILE *client_fd, char *request, size_t length) {
468 char buffer[MAX_REQUEST_LINE];
470 if (NULL == fgets(request, (int)length, client_fd)) {
471 if (ferror(client_fd)) {
472 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
479 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
481 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
485 if (ferror(client_fd)) {
486 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
493 static void send_bad_request(FILE *client_fd) {
494 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
495 fprintf(client_fd, "\r\n");
497 static void send_forwarding_failure(FILE *client_fd) {
498 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
499 fprintf(client_fd, "\r\n");
501 static void tls_send_invalid_cert_message(gnutls_session_t session) {
502 gnutls_record_send(session, "HTTP/1.0 500 Internal Server Error\r\n", 36);
503 gnutls_record_send(session, "\r\n", 2);
508 /* Transfer data between client and server sockets until one closes the
510 static void transfer_data(int client, int server) {
511 struct pollfd fds[2];
513 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
516 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
520 int result = poll(fds, 2, -1 /* no timeout */);
522 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
526 /* Data available from client. */
527 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
528 if (0 != read_from_write_to(client, server)) {
529 /* EOF (or other error) */
533 /* Data available from server. */
534 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
535 if (0 != read_from_write_to(server, client)) {
536 /* EOF (or other error) */
541 /* Client closed connection. */
542 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
545 /* Server closed connection. */
546 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
552 /* Read available data from socket from and write it to socket to. At maximum
553 * 4096 bytes are read/written. */
554 static int read_from_write_to(int from, int to) {
556 ssize_t size_written;
559 size_read = read(from, buffer, sizeof(buffer));
561 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
565 if (0 == size_read) {
569 size_written = write(to, buffer, (size_t)size_read);
570 if (0 > size_written) {
571 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
574 if (size_read != size_written) {
575 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
576 (long int)size_written, (long int)size_read);
584 /* Transfer data between client and server TLS connection until one closes the
586 static void transfer_data_tls(int client, int server,
587 gnutls_session_t client_session,
588 gnutls_session_t server_session) {
589 struct pollfd fds[2];
591 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
594 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
598 int result = poll(fds, 2, -1 /* no timeout */);
600 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
604 /* Data available from client. */
605 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
606 if (0 != read_from_write_to_tls(client_session, server_session)) {
607 /* EOF (or other error) */
611 /* Data available from server. */
612 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
613 if (0 != read_from_write_to_tls(server_session, client_session)) {
614 /* EOF (or other error) */
619 /* Client closed connection. */
620 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
623 /* Server closed connection. */
624 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
630 /* Read available data from session from and write to session to. */
631 static int read_from_write_to_tls(gnutls_session_t from,
632 gnutls_session_t to) {
635 ssize_t size_written;
638 /* Get maximum possible buffer size. */
639 size = gnutls_record_get_max_size(from);
640 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
642 if (size > gnutls_record_get_max_size(to)) {
643 size = gnutls_record_get_max_size(to);
645 if (size > sizeof(buffer)) {
646 size = sizeof(buffer);
648 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
651 size_read = gnutls_record_recv(from, buffer, size);
653 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
654 gnutls_strerror((int)size_read));
658 if (0 == size_read) {
662 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
663 if (0 > size_written) {
664 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
665 gnutls_strerror((int)size_written));
668 if (size_read != size_written) {
669 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
670 (long int)size_written, (long int)size_read);
678 static int connect_to_host(const char *hostname, const char *port) {
679 struct addrinfo gai_hints;
680 struct addrinfo *gai_result;
684 struct addrinfo *server;
686 if (NULL == hostname || NULL == port) {
690 /* Get IP of hostname server. */
691 memset(&gai_hints, 0, sizeof(gai_hints));
692 gai_hints.ai_family = AF_UNSPEC;
693 gai_hints.ai_socktype = SOCK_STREAM;
694 gai_hints.ai_protocol = 0;
695 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
696 | AI_ADDRCONFIG /* supported by this computer */
697 | AI_V4MAPPED; /* support IPv4 through IPv6 */
698 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
699 if (0 != gai_return) {
700 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
704 /* Now try to connect to each server returned by getaddrinfo(), use the
705 * first successful connect. */
706 for (server = gai_result; NULL != server; server = server->ai_next) {
707 server_socket = socket(server->ai_family,
709 server->ai_protocol);
710 if (-1 == server_socket) {
711 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
715 if (-1 != connect(server_socket, server->ai_addr,
716 server->ai_addrlen)) {
719 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
721 close(server_socket);
723 /* Make sure we free the result from getaddrinfo(). */
724 freeaddrinfo(gai_result);
726 if (NULL == server) {
727 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
731 return server_socket;
735 /* Parse HTTP CONNECT request string and save its parameters.
737 * The following format is expected: "CONNECT host:port HTTP/1.x".
739 * request and host must have the same size! port must be at least 6 bytes
742 static int parse_request(const char *request, char *host, char *port,
743 int *version_minor) {
744 int port_unused; /* just used to verify the port is numeric */
747 /* scanf() doesn't check spaces. */
748 if (0 != strncmp(request, "CONNECT ", 8)) {
751 /* Check request and extract data, "host:port" is not yet separated. */
752 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
753 host, version_minor)) {
756 /* Make sure ":port" is there. */
757 if (NULL == (position = strchr(host, ':'))) {
760 /* Make sure port is numeric. */
761 if (1 != sscanf(position + 1, "%d", &port_unused)) {
764 /* Store it in *port. */
765 strncpy(port, position + 1, 5);
767 /* And remove port from host. */