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"
33 /* Maximum line of a HTTP request line. Longer request lines are aborted with
34 * an error. The standard doesn't specify a maximum line length but this
35 * should be a good limit to make processing simpler. */
36 #define MAX_REQUEST_LINE 4096
39 static int initialize_tls_session_client(int peer_socket,
41 gnutls_session_t *session,
42 gnutls_certificate_credentials_t *x509_cred);
43 static int initialize_tls_session_server(int peer_socket,
44 gnutls_session_t *session,
45 gnutls_certificate_credentials_t *x509_cred);
47 static int read_http_request(FILE *client_fd, char *request, size_t length);
48 static void send_bad_request(FILE *client_fd);
49 static void send_forwarding_failure(FILE *client_fd);
52 static void transfer_data(int client, int server);
53 static int read_from_write_to(int from, int to);
55 static void transfer_data_tls(int client, int server,
56 gnutls_session_t client_session,
57 gnutls_session_t server_session);
58 static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to);
60 static int connect_to_host(const char *hostname, const char *port);
62 static int parse_request(const char *buffer, char *host, char *port,
66 void handle_connection(int client_socket) {
68 FILE *client_fd, *server_fd;
70 char buffer[MAX_REQUEST_LINE];
71 char host[MAX_REQUEST_LINE];
77 /* client_x509_cred is used when talking to the client (acting as a TSL
78 * server), server_x509_cred is used when talking to the server (acting as
80 gnutls_certificate_credentials_t client_x509_cred, server_x509_cred;
82 gnutls_session_t client_session, server_session;
83 /* initialize_tls_session_*() called? - used for goto out */
84 int client_session_init, server_session_init;
85 /* gnutls_handshake() called? - used for goto out */
86 int client_session_started, server_session_started;
88 LOG(LOG_DEBUG, "new connection");
93 client_session_init = 0;
94 server_session_init = 0;
95 client_session_started = 0;
96 server_session_started = 0;
98 client_fd = fdopen(client_socket, "a+");
99 if (NULL == client_fd) {
100 LOG_PERROR(LOG_WARNING, "fdopen(): client failed");
104 /* Read request line (CONNECT ..) and headers (they are discarded). */
105 result = read_http_request(client_fd, buffer, sizeof(buffer));
108 LOG(LOG_WARNING, "read_http_request(): client read error");
110 } else if (-2 == result) {
112 LOG(LOG_WARNING, "read_http_request(): client EOF");
113 send_bad_request(client_fd);
117 if (0 != parse_request(buffer, host, port, &version_minor)) {
118 LOG(LOG_WARNING, "bad request: %s", buffer);
119 send_bad_request(client_fd);
123 LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
125 /* Connect to proxy server or directly to server. */
126 if (NULL != global_proxy_host && NULL != global_proxy_port) {
127 LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host,
129 server_socket = connect_to_host(global_proxy_host, global_proxy_port);
131 LOG(LOG_DEBUG, "connecting to %s:%s", host, port);
132 server_socket = connect_to_host(host, port);
135 if (-1 == server_socket) {
136 LOG(LOG_WARNING, "failed to connect to server");
137 send_forwarding_failure(client_fd);
140 server_fd = fdopen(server_socket, "a+");
141 if (NULL == server_fd) {
142 LOG_PERROR(LOG_WARNING, "fdopen(): server failed");
143 send_forwarding_failure(client_fd);
147 /* Connect to proxy if requested (command line option). */
148 if (NULL != global_proxy_host && NULL != global_proxy_port) {
149 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
150 fprintf(server_fd, "\r\n");
152 /* Read response line from proxy server. */
153 result = read_http_request(server_fd, buffer, sizeof(buffer));
156 LOG(LOG_WARNING, "read_http_request(): proxy read error");
157 send_forwarding_failure(client_fd);
159 } else if (-2 == result) {
161 LOG(LOG_WARNING, "read_http_request(): proxy EOF");
162 send_forwarding_failure(client_fd);
166 /* Check response of proxy server. */
167 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
168 LOG(LOG_WARNING, "bad proxy response: %s", buffer);
169 send_forwarding_failure(client_fd);
174 LOG(LOG_DEBUG, "connection to server established");
176 /* We've established a connection, tell the client. */
177 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
178 fprintf(client_fd, "\r\n");
181 /* Initialize TLS server credentials to talk to the client. */
182 result = initialize_tls_session_client(client_socket, host,
186 LOG(LOG_WARNING, "initialize_tls_session_client() failed");
187 send_forwarding_failure(client_fd);
190 client_session_init = 1;
192 LOG(LOG_DEBUG, "starting client TLS handshake");
194 /* Try to establish TLS handshake between client and us. */
195 result = gnutls_handshake(client_session);
196 if (GNUTLS_E_SUCCESS != result) {
197 LOG(LOG_WARNING, "client TLS handshake failed: %s",
198 gnutls_strerror(result));
199 send_forwarding_failure(client_fd);
202 client_session_started = 1;
204 LOG(LOG_DEBUG, "client TLS handshake finished");
206 result = initialize_tls_session_server(server_socket, &server_session,
208 /* Initialize TLS client credentials to talk to the server. */
210 LOG(LOG_WARNING, "initialize_tls_session_server() failed");
211 send_forwarding_failure(client_fd);
214 server_session_init = 1;
216 LOG(LOG_DEBUG, "starting server TLS handshake");
218 /* Try to establish TLS handshake between us and server. */
219 result = gnutls_handshake(server_session);
220 if (GNUTLS_E_SUCCESS != result) {
221 LOG(LOG_WARNING, "server TLS handshake failed: %s",
222 gnutls_strerror(result));
223 send_forwarding_failure(client_fd);
226 server_session_started = 1;
228 LOG(LOG_DEBUG, "server TLS handshake finished, transferring data");
230 /* FIXME: verify server's fingerprint */
232 /* Proxy data between client and server until one suite is done (EOF or
234 transfer_data_tls(client_socket, server_socket,
235 client_session, server_session);
237 LOG(LOG_DEBUG, "finished transferring data");
240 /* Close TLS sessions if necessary. */
241 if (0 != server_session_started) {
242 gnutls_bye(server_session, GNUTLS_SHUT_WR);
244 if (0 != client_session_started) {
245 gnutls_bye(client_session, GNUTLS_SHUT_WR);
247 if (0 != server_session_init) {
248 gnutls_deinit(server_session);
249 gnutls_certificate_free_credentials(server_x509_cred);
251 if (0 != client_session_init) {
252 gnutls_deinit(client_session);
253 gnutls_certificate_free_cas(client_x509_cred);
254 gnutls_certificate_free_keys(client_x509_cred);
255 gnutls_certificate_free_credentials(client_x509_cred);
258 /* Close connection to server/proxy. */
259 if (NULL != server_fd) {
261 } else if (-1 != server_socket) {
262 close(server_socket);
264 LOG(LOG_DEBUG, "connection to server closed");
265 /* Close connection to client. */
266 if (NULL != client_fd) {
269 close(client_socket);
271 LOG(LOG_DEBUG, "connection to client closed");
273 LOG(LOG_DEBUG, "connection finished");
277 static int initialize_tls_session_client(int peer_socket,
278 const char *hostname,
279 gnutls_session_t *session,
280 gnutls_certificate_credentials_t *x509_cred) {
284 /* Hostname too long. */
285 if (sizeof(path) - strlen(PROXY_SERVER_CERT_FORMAT) <= strlen(hostname)) {
287 "initialize_tls_session_client(): hostname too long: '%s'",
291 /* Try to prevent path traversals in hostnames. */
292 if (NULL != strstr(hostname, "..")) {
294 "initialize_tls_session_client(): possible path traversal: '%s'",
298 snprintf(path, sizeof(path), PROXY_SERVER_CERT_FORMAT, hostname);
300 result = gnutls_certificate_allocate_credentials(x509_cred);
301 if (GNUTLS_E_SUCCESS != result) {
303 "initialize_tls_session_client(): \
304 gnutls_certificate_allocate_credentials(): %s",
305 gnutls_strerror(result));
309 /* Load proxy CA file, this CA "list" is send to the client. */
310 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
312 GNUTLS_X509_FMT_PEM);
315 "initialize_tls_session_client(): can't read CA file: '%s'",
319 /* And certificate for this website and proxy's private key. */
320 result = gnutls_certificate_set_x509_key_file(*x509_cred,
321 path, PROXY_KEY_FILE,
322 GNUTLS_X509_FMT_PEM);
323 if (GNUTLS_E_SUCCESS != result) {
325 "initialize_tls_session_client(): \
326 can't read server certificate ('%s') or key file ('%s'): %s",
327 path, PROXY_KEY_FILE, gnutls_strerror(result));
328 /* Could be a missing certificate. */
332 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
334 result = gnutls_init(session, GNUTLS_SERVER);
335 if (GNUTLS_E_SUCCESS != result) {
337 "initialize_tls_session_client(): gnutls_init(): %s",
338 gnutls_strerror(result));
341 result = gnutls_priority_set(*session, tls_priority_cache);
342 if (GNUTLS_E_SUCCESS != result) {
344 "initialize_tls_session_client(): gnutls_priority_set(): %s",
345 gnutls_strerror(result));
348 result = gnutls_credentials_set(*session,
349 GNUTLS_CRD_CERTIFICATE, *x509_cred);
350 if (GNUTLS_E_SUCCESS != result) {
352 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
353 gnutls_strerror(result));
357 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
361 static int initialize_tls_session_server(int peer_socket,
362 gnutls_session_t *session,
363 gnutls_certificate_credentials_t *x509_cred) {
366 result = gnutls_certificate_allocate_credentials(x509_cred);
367 if (GNUTLS_E_SUCCESS != result) {
369 "initialize_tls_session_server(): \
370 gnutls_certificate_allocate_credentials(): %s",
371 gnutls_strerror(result));
375 result = gnutls_init(session, GNUTLS_CLIENT);
376 if (GNUTLS_E_SUCCESS != result) {
378 "initialize_tls_session_server(): gnutls_init(): %s",
379 gnutls_strerror(result));
382 gnutls_priority_set(*session, tls_priority_cache);
383 if (GNUTLS_E_SUCCESS != result) {
385 "initialize_tls_session_server(): gnutls_priority_set(): %s",
386 gnutls_strerror(result));
389 result = gnutls_credentials_set(*session,
390 GNUTLS_CRD_CERTIFICATE, *x509_cred);
391 if (GNUTLS_E_SUCCESS != result) {
393 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
394 gnutls_strerror(result));
398 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
404 /* Read HTTP request line and headers (ignored).
406 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
408 static int read_http_request(FILE *client_fd, char *request, size_t length) {
409 char buffer[MAX_REQUEST_LINE];
411 if (NULL == fgets(request, (int)length, client_fd)) {
412 if (ferror(client_fd)) {
413 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
420 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
422 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
426 if (ferror(client_fd)) {
427 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
434 static void send_bad_request(FILE *client_fd) {
435 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
436 fprintf(client_fd, "\r\n");
438 static void send_forwarding_failure(FILE *client_fd) {
439 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
440 fprintf(client_fd, "\r\n");
445 /* Transfer data between client and server sockets until one closes the
447 static void transfer_data(int client, int server) {
448 struct pollfd fds[2];
450 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
453 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
457 int result = poll(fds, 2, -1 /* no timeout */);
459 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
463 /* Data available from client. */
464 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
465 if (0 != read_from_write_to(client, server)) {
466 /* EOF (or other error) */
470 /* Data available from server. */
471 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
472 if (0 != read_from_write_to(server, client)) {
473 /* EOF (or other error) */
478 /* Client closed connection. */
479 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
482 /* Server closed connection. */
483 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
489 /* Read available data from socket from and write it to socket to. At maximum
490 * 4096 bytes are read/written. */
491 static int read_from_write_to(int from, int to) {
493 ssize_t size_written;
496 size_read = read(from, buffer, sizeof(buffer));
498 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
502 if (0 == size_read) {
506 size_written = write(to, buffer, (size_t)size_read);
507 if (0 > size_written) {
508 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
511 if (size_read != size_written) {
512 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
513 (long int)size_written, (long int)size_read);
521 /* Transfer data between client and server TLS connection until one closes the
523 static void transfer_data_tls(int client, int server,
524 gnutls_session_t client_session,
525 gnutls_session_t server_session) {
526 struct pollfd fds[2];
528 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
531 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
535 int result = poll(fds, 2, -1 /* no timeout */);
537 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
541 /* Data available from client. */
542 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
543 if (0 != read_from_write_to_tls(client_session, server_session)) {
544 /* EOF (or other error) */
548 /* Data available from server. */
549 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
550 if (0 != read_from_write_to_tls(server_session, client_session)) {
551 /* EOF (or other error) */
556 /* Client closed connection. */
557 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
560 /* Server closed connection. */
561 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
567 /* Read available data from session from and write to session to. */
568 static int read_from_write_to_tls(gnutls_session_t from,
569 gnutls_session_t to) {
572 ssize_t size_written;
575 /* Get maximum possible buffer size. */
576 size = gnutls_record_get_max_size(from);
577 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
579 if (size > gnutls_record_get_max_size(to)) {
580 size = gnutls_record_get_max_size(to);
582 if (size > sizeof(buffer)) {
583 size = sizeof(buffer);
585 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
588 size_read = gnutls_record_recv(from, buffer, size);
590 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
591 gnutls_strerror((int)size_read));
595 if (0 == size_read) {
599 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
600 if (0 > size_written) {
601 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
602 gnutls_strerror((int)size_written));
605 if (size_read != size_written) {
606 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
607 (long int)size_written, (long int)size_read);
615 static int connect_to_host(const char *hostname, const char *port) {
616 struct addrinfo gai_hints;
617 struct addrinfo *gai_result;
621 struct addrinfo *server;
623 if (NULL == hostname || NULL == port) {
627 /* Get IP of hostname server. */
628 memset(&gai_hints, 0, sizeof(gai_hints));
629 gai_hints.ai_family = AF_UNSPEC;
630 gai_hints.ai_socktype = SOCK_STREAM;
631 gai_hints.ai_protocol = 0;
632 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
633 | AI_ADDRCONFIG /* supported by this computer */
634 | AI_V4MAPPED; /* support IPv4 through IPv6 */
635 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
636 if (0 != gai_return) {
637 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
641 /* Now try to connect to each server returned by getaddrinfo(), use the
642 * first successful connect. */
643 for (server = gai_result; NULL != server; server = server->ai_next) {
644 server_socket = socket(server->ai_family,
646 server->ai_protocol);
647 if (-1 == server_socket) {
648 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
652 if (-1 != connect(server_socket, server->ai_addr,
653 server->ai_addrlen)) {
656 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
658 close(server_socket);
660 /* Make sure we free the result from getaddrinfo(). */
661 freeaddrinfo(gai_result);
663 if (NULL == server) {
664 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
668 return server_socket;
672 /* Parse HTTP CONNECT request string and save its parameters.
674 * The following format is expected: "CONNECT host:port HTTP/1.x".
676 * request and host must have the same size! port must be at least 6 bytes
679 static int parse_request(const char *request, char *host, char *port,
680 int *version_minor) {
681 int port_unused; /* just used to verify the port is numeric */
684 /* scanf() doesn't check spaces. */
685 if (0 != strncmp(request, "CONNECT ", 8)) {
688 /* Check request and extract data, "host:port" is not yet separated. */
689 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
690 host, version_minor)) {
693 /* Make sure ":port" is there. */
694 if (NULL == (position = strchr(host, ':'))) {
697 /* Make sure port is numeric. */
698 if (1 != sscanf(position + 1, "%d", &port_unused)) {
701 /* Store it in *port. */
702 strncpy(port, position + 1, 5);
704 /* And remove port from host. */