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
39 /* Format string used to send HTTP/1.0 error responses to the client.
41 * %s is used 4 times, first three are the error code (no %n$s!), the last is
43 #define HTTP_RESPONSE_FORMAT "HTTP/1.0 %s\r\n\
44 Content-Type: text/html; charset=US-ASCII\r\n\
46 <!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n\
48 <head><title>%s</title></head>\n\
56 static int initialize_tls_session_client(int peer_socket,
58 gnutls_session_t *session,
59 gnutls_certificate_credentials_t *x509_cred);
60 static int initialize_tls_session_server(int peer_socket,
61 gnutls_session_t *session,
62 gnutls_certificate_credentials_t *x509_cred);
64 static int read_http_request(FILE *client_fd, char *request, size_t length);
65 static void send_bad_request(FILE *client_fd);
66 static void send_forwarding_failure(FILE *client_fd);
67 static void tls_send_invalid_cert_message(gnutls_session_t session);
69 static void transfer_data(int client, int server);
70 static int read_from_write_to(int from, int to);
71 static void transfer_data_tls(int client, int server,
72 gnutls_session_t client_session,
73 gnutls_session_t server_session);
74 static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to);
76 static int connect_to_host(const char *hostname, const char *port);
78 static int parse_request(const char *buffer, char *host, char *port,
82 void handle_connection(int client_socket) {
84 FILE *client_fd, *server_fd;
86 char buffer[MAX_REQUEST_LINE];
87 char host[MAX_REQUEST_LINE];
93 /* client_x509_cred is used when talking to the client (acting as a TSL
94 * server), server_x509_cred is used when talking to the server (acting as
96 gnutls_certificate_credentials_t client_x509_cred, server_x509_cred;
98 gnutls_session_t client_session, server_session;
99 /* initialize_tls_session_*() called? - used for goto out */
100 int client_session_init, server_session_init;
101 /* gnutls_handshake() called? - used for goto out */
102 int client_session_started, server_session_started;
103 /* Validation failed? If yes we need to send the special "invalid"
105 int validation_failed;
107 LOG(LOG_DEBUG, "new connection");
112 client_session_init = 0;
113 server_session_init = 0;
114 client_session_started = 0;
115 server_session_started = 0;
116 validation_failed = 0;
118 client_fd = fdopen(client_socket, "a+");
119 if (NULL == client_fd) {
120 LOG_PERROR(LOG_WARNING, "fdopen(): client failed");
124 /* Read request line (CONNECT ..) and headers (they are discarded). */
125 result = read_http_request(client_fd, buffer, sizeof(buffer));
128 LOG(LOG_WARNING, "read_http_request(): client read error");
130 } else if (-2 == result) {
132 LOG(LOG_WARNING, "read_http_request(): client EOF");
133 send_bad_request(client_fd);
137 if (0 != parse_request(buffer, host, port, &version_minor)) {
138 LOG(LOG_WARNING, "bad request: %s", buffer);
139 send_bad_request(client_fd);
143 LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
145 /* Connect to proxy server or directly to server. */
146 if (NULL != global_proxy_host && NULL != global_proxy_port) {
147 LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host,
149 server_socket = connect_to_host(global_proxy_host, global_proxy_port);
151 LOG(LOG_DEBUG, "connecting to %s:%s", host, port);
152 server_socket = connect_to_host(host, port);
155 if (-1 == server_socket) {
156 LOG(LOG_WARNING, "failed to connect to server");
157 send_forwarding_failure(client_fd);
160 server_fd = fdopen(server_socket, "a+");
161 if (NULL == server_fd) {
162 LOG_PERROR(LOG_WARNING, "fdopen(): server failed");
163 send_forwarding_failure(client_fd);
167 /* Connect to proxy if requested (command line option). */
168 if (NULL != global_proxy_host && NULL != global_proxy_port) {
169 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
170 fprintf(server_fd, "\r\n");
172 /* Read response line from proxy server. */
173 result = read_http_request(server_fd, buffer, sizeof(buffer));
176 LOG(LOG_WARNING, "read_http_request(): proxy read error");
177 send_forwarding_failure(client_fd);
179 } else if (-2 == result) {
181 LOG(LOG_WARNING, "read_http_request(): proxy EOF");
182 send_forwarding_failure(client_fd);
186 /* Check response of proxy server. */
187 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
188 LOG(LOG_WARNING, "bad proxy response: %s", buffer);
189 send_forwarding_failure(client_fd);
194 LOG(LOG_DEBUG, "connection to server established");
196 /* If the -u option is used and we don't know this hostname's server
197 * certificate then just pass through the connection and let the client
198 * verify the server certificate. */
199 if (global_passthrough_unknown) {
203 if (-2 == server_certificate_path(&file, host, path, sizeof(path))) {
204 /* We've established a connection, tell the client. */
205 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
206 fprintf(client_fd, "\r\n");
209 LOG(LOG_DEBUG, "transferring data");
211 /* Proxy data between client and server until one suite is done
213 transfer_data(client_socket, server_socket);
215 LOG(LOG_DEBUG, "finished transferring data");
219 /* server_certificate_path() may open the file, close it. */
225 result = initialize_tls_session_server(server_socket, &server_session,
227 /* Initialize TLS client credentials to talk to the server. */
229 LOG(LOG_WARNING, "initialize_tls_session_server() failed");
230 send_forwarding_failure(client_fd);
233 server_session_init = 1;
235 LOG(LOG_DEBUG, "starting server TLS handshake");
237 /* Try to establish TLS handshake between us and server. */
238 result = gnutls_handshake(server_session);
239 if (GNUTLS_E_SUCCESS != result) {
240 LOG(LOG_WARNING, "server TLS handshake failed: %s",
241 gnutls_strerror(result));
242 send_forwarding_failure(client_fd);
245 server_session_started = 1;
247 LOG(LOG_DEBUG, "server TLS handshake finished");
249 /* Make sure the server certificate is valid and known. */
250 if (0 != verify_tls_connection(server_session, host)) {
251 LOG(LOG_ERROR, "server certificate validation failed!");
252 /* We send the error message over our TLS connection to the client,
253 * but with an invalid certificate. */
254 validation_failed = 1;
257 /* Initialize TLS server credentials to talk to the client. */
258 result = initialize_tls_session_client(client_socket,
259 /* use special host if the server
260 * certificate was invalid */
261 (validation_failed) ? "invalid"
266 LOG(LOG_WARNING, "initialize_tls_session_client() failed");
267 send_forwarding_failure(client_fd);
270 client_session_init = 1;
272 /* We've established a connection, tell the client. */
273 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
274 fprintf(client_fd, "\r\n");
277 LOG(LOG_DEBUG, "starting client TLS handshake");
279 /* Try to establish TLS handshake between client and us. */
280 result = gnutls_handshake(client_session);
281 if (GNUTLS_E_SUCCESS != result) {
282 LOG(LOG_WARNING, "client TLS handshake failed: %s",
283 gnutls_strerror(result));
284 send_forwarding_failure(client_fd);
287 client_session_started = 1;
289 LOG(LOG_DEBUG, "client TLS handshake finished");
291 /* Tell the client that the verification failed. Shouldn't be necessary as
292 * the client should terminate the connection because he received the
293 * invalid certificate but better be sure. */
294 if (validation_failed) {
295 tls_send_invalid_cert_message(client_session);
299 LOG(LOG_DEBUG, "transferring TLS data");
301 /* Proxy data between client and server until one suite is done (EOF or
303 transfer_data_tls(client_socket, server_socket,
304 client_session, server_session);
306 LOG(LOG_DEBUG, "finished transferring TLS data");
309 /* Close TLS sessions if necessary. Use GNUTLS_SHUT_RDWR so the data is
310 * reliable transmitted. */
311 if (0 != server_session_started) {
312 gnutls_bye(server_session, GNUTLS_SHUT_RDWR);
314 if (0 != client_session_started) {
315 gnutls_bye(client_session, GNUTLS_SHUT_RDWR);
317 if (0 != server_session_init) {
318 gnutls_deinit(server_session);
319 gnutls_certificate_free_credentials(server_x509_cred);
321 if (0 != client_session_init) {
322 gnutls_deinit(client_session);
323 gnutls_certificate_free_cas(client_x509_cred);
324 gnutls_certificate_free_keys(client_x509_cred);
325 gnutls_certificate_free_credentials(client_x509_cred);
328 /* Close connection to server/proxy. */
329 if (NULL != server_fd) {
331 } else if (-1 != server_socket) {
332 close(server_socket);
334 LOG(LOG_DEBUG, "connection to server closed");
335 /* Close connection to client. */
336 if (NULL != client_fd) {
339 close(client_socket);
341 LOG(LOG_DEBUG, "connection to client closed");
343 LOG(LOG_DEBUG, "connection finished");
347 static int initialize_tls_session_client(int peer_socket,
348 const char *hostname,
349 gnutls_session_t *session,
350 gnutls_certificate_credentials_t *x509_cred) {
352 int use_invalid_cert;
355 /* The "invalid" hostname is special. If it's used we send an invalid
356 * certificate to let the client know something is wrong. */
357 use_invalid_cert = 0 == strcmp(hostname, "invalid");
359 /* Hostname too long. */
360 if (sizeof(path) - strlen(PROXY_SERVER_CERT_FORMAT) <= strlen(hostname)) {
362 "initialize_tls_session_client(): hostname too long: '%s'",
366 /* Try to prevent path traversals in hostnames. */
367 if (NULL != strstr(hostname, "..")) {
369 "initialize_tls_session_client(): possible path traversal: '%s'",
373 snprintf(path, sizeof(path), PROXY_SERVER_CERT_FORMAT, hostname);
375 result = gnutls_certificate_allocate_credentials(x509_cred);
376 if (GNUTLS_E_SUCCESS != result) {
378 "initialize_tls_session_client(): \
379 gnutls_certificate_allocate_credentials(): %s",
380 gnutls_strerror(result));
384 /* Load proxy CA file, this CA "list" is send to the client. */
385 if (!use_invalid_cert) {
386 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
388 GNUTLS_X509_FMT_PEM);
389 /* If the invalid hostname was specified do nothing, we use a self-signed
390 * certificate in this case. */
396 "initialize_tls_session_client(): can't read CA file: '%s'",
398 gnutls_certificate_free_credentials(*x509_cred);
401 /* And certificate for this website and proxy's private key. */
402 if (!use_invalid_cert) {
403 result = gnutls_certificate_set_x509_key_file(*x509_cred,
404 path, PROXY_KEY_FILE,
405 GNUTLS_X509_FMT_PEM);
406 /* If the invalid hostname was specified load our special "invalid"
409 result = gnutls_certificate_set_x509_key_file(*x509_cred,
410 PROXY_INVALID_CERT_FILE,
412 GNUTLS_X509_FMT_PEM);
414 if (GNUTLS_E_SUCCESS != result) {
416 "initialize_tls_session_client(): \
417 can't read server certificate ('%s') or key file ('%s'): %s",
418 path, PROXY_KEY_FILE, gnutls_strerror(result));
419 gnutls_certificate_free_credentials(*x509_cred);
420 /* Could be a missing certificate. */
424 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
426 result = gnutls_init(session, GNUTLS_SERVER);
427 if (GNUTLS_E_SUCCESS != result) {
429 "initialize_tls_session_client(): gnutls_init(): %s",
430 gnutls_strerror(result));
431 gnutls_certificate_free_credentials(*x509_cred);
434 result = gnutls_priority_set(*session, tls_priority_cache);
435 if (GNUTLS_E_SUCCESS != result) {
437 "initialize_tls_session_client(): gnutls_priority_set(): %s",
438 gnutls_strerror(result));
439 gnutls_deinit(*session);
440 gnutls_certificate_free_credentials(*x509_cred);
443 result = gnutls_credentials_set(*session,
444 GNUTLS_CRD_CERTIFICATE, *x509_cred);
445 if (GNUTLS_E_SUCCESS != result) {
447 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
448 gnutls_strerror(result));
449 gnutls_deinit(*session);
450 gnutls_certificate_free_credentials(*x509_cred);
454 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
458 static int initialize_tls_session_server(int peer_socket,
459 gnutls_session_t *session,
460 gnutls_certificate_credentials_t *x509_cred) {
463 result = gnutls_certificate_allocate_credentials(x509_cred);
464 if (GNUTLS_E_SUCCESS != result) {
466 "initialize_tls_session_server(): \
467 gnutls_certificate_allocate_credentials(): %s",
468 gnutls_strerror(result));
472 result = gnutls_init(session, GNUTLS_CLIENT);
473 if (GNUTLS_E_SUCCESS != result) {
475 "initialize_tls_session_server(): gnutls_init(): %s",
476 gnutls_strerror(result));
477 gnutls_certificate_free_credentials(*x509_cred);
480 gnutls_priority_set(*session, tls_priority_cache);
481 if (GNUTLS_E_SUCCESS != result) {
483 "initialize_tls_session_server(): gnutls_priority_set(): %s",
484 gnutls_strerror(result));
485 gnutls_deinit(*session);
486 gnutls_certificate_free_credentials(*x509_cred);
489 result = gnutls_credentials_set(*session,
490 GNUTLS_CRD_CERTIFICATE, *x509_cred);
491 if (GNUTLS_E_SUCCESS != result) {
493 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
494 gnutls_strerror(result));
495 gnutls_deinit(*session);
496 gnutls_certificate_free_credentials(*x509_cred);
500 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
506 /* Read HTTP request line and headers (ignored).
508 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
510 static int read_http_request(FILE *client_fd, char *request, size_t length) {
511 char buffer[MAX_REQUEST_LINE];
513 if (NULL == fgets(request, (int)length, client_fd)) {
514 if (ferror(client_fd)) {
515 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
522 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
524 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
528 if (ferror(client_fd)) {
529 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
536 static void send_bad_request(FILE *client_fd) {
537 #define RESPONSE_ERROR "400 Bad Request"
538 #define RESPONSE_MSG "Your browser sent an invalid request."
539 fprintf(client_fd, HTTP_RESPONSE_FORMAT,
540 RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR,
542 #undef RESPONSE_ERROR
545 static void send_forwarding_failure(FILE *client_fd) {
546 #define RESPONSE_ERROR "503 Forwarding failure"
547 #define RESPONSE_MSG "Failed to connect to server, check logs."
548 fprintf(client_fd, HTTP_RESPONSE_FORMAT,
549 RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR,
551 #undef RESPONSE_ERROR
554 static void tls_send_invalid_cert_message(gnutls_session_t session) {
555 #define RESPONSE_ERROR "500 Internal Server Error"
556 #define RESPONSE_MSG "Server certificate validation failed, check logs."
558 char buffer[sizeof(HTTP_RESPONSE_FORMAT) - 1 /* '\0' */
559 - 4 * 2 /* four %s */
560 + (sizeof(RESPONSE_ERROR) - 1 /* '\0' */) * 3
561 + sizeof(RESPONSE_MSG) - 1 /* '\0' */
564 snprintf(buffer, sizeof(buffer),
565 HTTP_RESPONSE_FORMAT,
566 RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_MSG);
568 gnutls_record_send(session, buffer, sizeof(buffer) - 1);
569 /* don't send trailing '\0' */
570 #undef RESPONSE_ERROR
575 /* Transfer data between client and server sockets until one closes the
577 static void transfer_data(int client, int server) {
578 struct pollfd fds[2];
580 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
583 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
587 int result = poll(fds, 2, -1 /* no timeout */);
589 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
593 /* Data available from client. */
594 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
595 if (0 != read_from_write_to(client, server)) {
596 /* EOF (or other error) */
600 /* Data available from server. */
601 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
602 if (0 != read_from_write_to(server, client)) {
603 /* EOF (or other error) */
608 /* Client closed connection. */
609 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
612 /* Server closed connection. */
613 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
619 /* Read available data from socket from and write it to socket to. At maximum
620 * 4096 bytes are read/written. */
621 static int read_from_write_to(int from, int to) {
623 ssize_t size_written;
626 LOG(LOG_DEBUG, "read_from_write_to(): %d -> %d", from, to);
628 size_read = read(from, buffer, sizeof(buffer));
630 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
634 if (0 == size_read) {
638 size_written = write(to, buffer, (size_t)size_read);
639 if (0 > size_written) {
640 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
643 if (size_read != size_written) {
644 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
645 (long int)size_written, (long int)size_read);
652 /* Transfer data between client and server TLS connection until one closes the
654 static void transfer_data_tls(int client, int server,
655 gnutls_session_t client_session,
656 gnutls_session_t server_session) {
657 struct pollfd fds[2];
659 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
662 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
666 int result = poll(fds, 2, -1 /* no timeout */);
668 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
672 /* Data available from client. */
673 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
674 if (0 != read_from_write_to_tls(client_session, server_session)) {
675 /* EOF (or other error) */
679 /* Data available from server. */
680 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
681 if (0 != read_from_write_to_tls(server_session, client_session)) {
682 /* EOF (or other error) */
687 /* Client closed connection. */
688 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
691 /* Server closed connection. */
692 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
698 /* Read available data from session from and write to session to. */
699 static int read_from_write_to_tls(gnutls_session_t from,
700 gnutls_session_t to) {
703 ssize_t size_written;
706 /* Get maximum possible buffer size. */
707 size = gnutls_record_get_max_size(from);
708 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
710 if (size > gnutls_record_get_max_size(to)) {
711 size = gnutls_record_get_max_size(to);
713 if (size > sizeof(buffer)) {
714 size = sizeof(buffer);
716 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
719 size_read = gnutls_record_recv(from, buffer, size);
721 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
722 gnutls_strerror((int)size_read));
726 if (0 == size_read) {
730 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
731 if (0 > size_written) {
732 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
733 gnutls_strerror((int)size_written));
736 if (size_read != size_written) {
737 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
738 (long int)size_written, (long int)size_read);
746 static int connect_to_host(const char *hostname, const char *port) {
747 struct addrinfo gai_hints;
748 struct addrinfo *gai_result;
752 struct addrinfo *server;
754 if (NULL == hostname || NULL == port) {
758 /* Get IP of hostname server. */
759 memset(&gai_hints, 0, sizeof(gai_hints));
760 gai_hints.ai_family = AF_UNSPEC;
761 gai_hints.ai_socktype = SOCK_STREAM;
762 gai_hints.ai_protocol = 0;
763 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
764 | AI_ADDRCONFIG /* supported by this computer */
765 | AI_V4MAPPED; /* support IPv4 through IPv6 */
766 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
767 if (0 != gai_return) {
768 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
772 /* Now try to connect to each server returned by getaddrinfo(), use the
773 * first successful connect. */
774 for (server = gai_result; NULL != server; server = server->ai_next) {
775 server_socket = socket(server->ai_family,
777 server->ai_protocol);
778 if (-1 == server_socket) {
779 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
783 if (-1 != connect(server_socket, server->ai_addr,
784 server->ai_addrlen)) {
787 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
789 close(server_socket);
791 /* Make sure we free the result from getaddrinfo(). */
792 freeaddrinfo(gai_result);
794 if (NULL == server) {
795 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
799 return server_socket;
803 /* Parse HTTP CONNECT request string and save its parameters.
805 * The following format is expected: "CONNECT host:port HTTP/1.x".
807 * request and host must have the same size! port must be at least 6 bytes
810 static int parse_request(const char *request, char *host, char *port,
811 int *version_minor) {
812 int port_unused; /* just used to verify the port is numeric */
815 /* scanf() doesn't check spaces. */
816 if (0 != strncmp(request, "CONNECT ", 8)) {
819 /* Check request and extract data, "host:port" is not yet separated. */
820 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
821 host, version_minor)) {
824 /* Make sure ":port" is there. */
825 if (NULL == (position = strchr(host, ':'))) {
828 /* Make sure port is numeric. */
829 if (1 != sscanf(position + 1, "%d", &port_unused)) {
832 /* Store it in *port. */
833 strncpy(port, position + 1, 5);
835 /* And remove port from host. */