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_server_error(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;
90 LOG(LOG_DEBUG, "new connection");
95 client_session_init = 0;
96 server_session_init = 0;
97 client_session_started = 0;
98 server_session_started = 0;
100 client_fd = fdopen(client_socket, "a+");
101 if (NULL == client_fd) {
102 LOG_PERROR(LOG_WARNING, "fdopen(): client failed");
106 /* Read request line (CONNECT ..) and headers (they are discarded). */
107 result = read_http_request(client_fd, buffer, sizeof(buffer));
110 LOG(LOG_WARNING, "read_http_request(): client read error");
112 } else if (-2 == result) {
114 LOG(LOG_WARNING, "read_http_request(): client EOF");
115 send_bad_request(client_fd);
119 if (0 != parse_request(buffer, host, port, &version_minor)) {
120 LOG(LOG_WARNING, "bad request: %s", buffer);
121 send_bad_request(client_fd);
125 LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
127 /* Connect to proxy server or directly to server. */
128 if (NULL != global_proxy_host && NULL != global_proxy_port) {
129 LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host,
131 server_socket = connect_to_host(global_proxy_host, global_proxy_port);
133 LOG(LOG_DEBUG, "connecting to %s:%s", host, port);
134 server_socket = connect_to_host(host, port);
137 if (-1 == server_socket) {
138 LOG(LOG_WARNING, "failed to connect to server");
139 send_forwarding_failure(client_fd);
142 server_fd = fdopen(server_socket, "a+");
143 if (NULL == server_fd) {
144 LOG_PERROR(LOG_WARNING, "fdopen(): server failed");
145 send_forwarding_failure(client_fd);
149 /* Connect to proxy if requested (command line option). */
150 if (NULL != global_proxy_host && NULL != global_proxy_port) {
151 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
152 fprintf(server_fd, "\r\n");
154 /* Read response line from proxy server. */
155 result = read_http_request(server_fd, buffer, sizeof(buffer));
158 LOG(LOG_WARNING, "read_http_request(): proxy read error");
159 send_forwarding_failure(client_fd);
161 } else if (-2 == result) {
163 LOG(LOG_WARNING, "read_http_request(): proxy EOF");
164 send_forwarding_failure(client_fd);
168 /* Check response of proxy server. */
169 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
170 LOG(LOG_WARNING, "bad proxy response: %s", buffer);
171 send_forwarding_failure(client_fd);
176 LOG(LOG_DEBUG, "connection to server established");
178 /* We've established a connection, tell the client. */
179 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
180 fprintf(client_fd, "\r\n");
183 /* Initialize TLS server credentials to talk to the client. */
184 result = initialize_tls_session_client(client_socket, host,
188 LOG(LOG_WARNING, "initialize_tls_session_client() failed");
189 send_forwarding_failure(client_fd);
192 client_session_init = 1;
194 LOG(LOG_DEBUG, "starting client TLS handshake");
196 /* Try to establish TLS handshake between client and us. */
197 result = gnutls_handshake(client_session);
198 if (GNUTLS_E_SUCCESS != result) {
199 LOG(LOG_WARNING, "client TLS handshake failed: %s",
200 gnutls_strerror(result));
201 send_forwarding_failure(client_fd);
204 client_session_started = 1;
206 LOG(LOG_DEBUG, "client TLS handshake finished");
208 result = initialize_tls_session_server(server_socket, &server_session,
210 /* Initialize TLS client credentials to talk to the server. */
212 LOG(LOG_WARNING, "initialize_tls_session_server() failed");
213 send_forwarding_failure(client_fd);
216 server_session_init = 1;
218 LOG(LOG_DEBUG, "starting server TLS handshake");
220 /* Try to establish TLS handshake between us and server. */
221 result = gnutls_handshake(server_session);
222 if (GNUTLS_E_SUCCESS != result) {
223 LOG(LOG_WARNING, "server TLS handshake failed: %s",
224 gnutls_strerror(result));
225 send_forwarding_failure(client_fd);
228 server_session_started = 1;
230 LOG(LOG_DEBUG, "server TLS handshake finished, transferring data");
232 /* Make sure the server certificate is valid and known. */
233 if (0 != verify_tls_connection(server_session, host)) {
234 LOG(LOG_ERROR, "server certificate validation failed!");
235 tls_send_server_error(client_session);
239 /* Proxy data between client and server until one suite is done (EOF or
241 transfer_data_tls(client_socket, server_socket,
242 client_session, server_session);
244 LOG(LOG_DEBUG, "finished transferring data");
247 /* Close TLS sessions if necessary. Use GNUTLS_SHUT_RDWR so the data is
248 * reliable transmitted. */
249 if (0 != server_session_started) {
250 gnutls_bye(server_session, GNUTLS_SHUT_RDWR);
252 if (0 != client_session_started) {
253 gnutls_bye(client_session, GNUTLS_SHUT_RDWR);
255 if (0 != server_session_init) {
256 gnutls_deinit(server_session);
257 gnutls_certificate_free_credentials(server_x509_cred);
259 if (0 != client_session_init) {
260 gnutls_deinit(client_session);
261 gnutls_certificate_free_cas(client_x509_cred);
262 gnutls_certificate_free_keys(client_x509_cred);
263 gnutls_certificate_free_credentials(client_x509_cred);
266 /* Close connection to server/proxy. */
267 if (NULL != server_fd) {
269 } else if (-1 != server_socket) {
270 close(server_socket);
272 LOG(LOG_DEBUG, "connection to server closed");
273 /* Close connection to client. */
274 if (NULL != client_fd) {
277 close(client_socket);
279 LOG(LOG_DEBUG, "connection to client closed");
281 LOG(LOG_DEBUG, "connection finished");
285 static int initialize_tls_session_client(int peer_socket,
286 const char *hostname,
287 gnutls_session_t *session,
288 gnutls_certificate_credentials_t *x509_cred) {
292 /* Hostname too long. */
293 if (sizeof(path) - strlen(PROXY_SERVER_CERT_FORMAT) <= strlen(hostname)) {
295 "initialize_tls_session_client(): hostname too long: '%s'",
299 /* Try to prevent path traversals in hostnames. */
300 if (NULL != strstr(hostname, "..")) {
302 "initialize_tls_session_client(): possible path traversal: '%s'",
306 snprintf(path, sizeof(path), PROXY_SERVER_CERT_FORMAT, hostname);
308 result = gnutls_certificate_allocate_credentials(x509_cred);
309 if (GNUTLS_E_SUCCESS != result) {
311 "initialize_tls_session_client(): \
312 gnutls_certificate_allocate_credentials(): %s",
313 gnutls_strerror(result));
317 /* Load proxy CA file, this CA "list" is send to the client. */
318 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
320 GNUTLS_X509_FMT_PEM);
323 "initialize_tls_session_client(): can't read CA file: '%s'",
327 /* And certificate for this website and proxy's private key. */
328 result = gnutls_certificate_set_x509_key_file(*x509_cred,
329 path, PROXY_KEY_FILE,
330 GNUTLS_X509_FMT_PEM);
331 if (GNUTLS_E_SUCCESS != result) {
333 "initialize_tls_session_client(): \
334 can't read server certificate ('%s') or key file ('%s'): %s",
335 path, PROXY_KEY_FILE, gnutls_strerror(result));
336 /* Could be a missing certificate. */
340 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
342 result = gnutls_init(session, GNUTLS_SERVER);
343 if (GNUTLS_E_SUCCESS != result) {
345 "initialize_tls_session_client(): gnutls_init(): %s",
346 gnutls_strerror(result));
349 result = gnutls_priority_set(*session, tls_priority_cache);
350 if (GNUTLS_E_SUCCESS != result) {
352 "initialize_tls_session_client(): gnutls_priority_set(): %s",
353 gnutls_strerror(result));
356 result = gnutls_credentials_set(*session,
357 GNUTLS_CRD_CERTIFICATE, *x509_cred);
358 if (GNUTLS_E_SUCCESS != result) {
360 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
361 gnutls_strerror(result));
365 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
369 static int initialize_tls_session_server(int peer_socket,
370 gnutls_session_t *session,
371 gnutls_certificate_credentials_t *x509_cred) {
374 result = gnutls_certificate_allocate_credentials(x509_cred);
375 if (GNUTLS_E_SUCCESS != result) {
377 "initialize_tls_session_server(): \
378 gnutls_certificate_allocate_credentials(): %s",
379 gnutls_strerror(result));
383 result = gnutls_init(session, GNUTLS_CLIENT);
384 if (GNUTLS_E_SUCCESS != result) {
386 "initialize_tls_session_server(): gnutls_init(): %s",
387 gnutls_strerror(result));
390 gnutls_priority_set(*session, tls_priority_cache);
391 if (GNUTLS_E_SUCCESS != result) {
393 "initialize_tls_session_server(): gnutls_priority_set(): %s",
394 gnutls_strerror(result));
397 result = gnutls_credentials_set(*session,
398 GNUTLS_CRD_CERTIFICATE, *x509_cred);
399 if (GNUTLS_E_SUCCESS != result) {
401 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
402 gnutls_strerror(result));
406 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
412 /* Read HTTP request line and headers (ignored).
414 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
416 static int read_http_request(FILE *client_fd, char *request, size_t length) {
417 char buffer[MAX_REQUEST_LINE];
419 if (NULL == fgets(request, (int)length, client_fd)) {
420 if (ferror(client_fd)) {
421 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
428 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
430 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
434 if (ferror(client_fd)) {
435 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
442 static void send_bad_request(FILE *client_fd) {
443 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
444 fprintf(client_fd, "\r\n");
446 static void send_forwarding_failure(FILE *client_fd) {
447 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
448 fprintf(client_fd, "\r\n");
450 static void tls_send_server_error(gnutls_session_t session) {
451 gnutls_record_send(session, "HTTP/1.0 500 Internal Server Error\r\n", 36);
452 gnutls_record_send(session, "\r\n", 2);
457 /* Transfer data between client and server sockets until one closes the
459 static void transfer_data(int client, int server) {
460 struct pollfd fds[2];
462 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
465 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
469 int result = poll(fds, 2, -1 /* no timeout */);
471 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
475 /* Data available from client. */
476 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
477 if (0 != read_from_write_to(client, server)) {
478 /* EOF (or other error) */
482 /* Data available from server. */
483 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
484 if (0 != read_from_write_to(server, client)) {
485 /* EOF (or other error) */
490 /* Client closed connection. */
491 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
494 /* Server closed connection. */
495 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
501 /* Read available data from socket from and write it to socket to. At maximum
502 * 4096 bytes are read/written. */
503 static int read_from_write_to(int from, int to) {
505 ssize_t size_written;
508 size_read = read(from, buffer, sizeof(buffer));
510 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
514 if (0 == size_read) {
518 size_written = write(to, buffer, (size_t)size_read);
519 if (0 > size_written) {
520 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
523 if (size_read != size_written) {
524 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
525 (long int)size_written, (long int)size_read);
533 /* Transfer data between client and server TLS connection until one closes the
535 static void transfer_data_tls(int client, int server,
536 gnutls_session_t client_session,
537 gnutls_session_t server_session) {
538 struct pollfd fds[2];
540 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
543 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
547 int result = poll(fds, 2, -1 /* no timeout */);
549 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
553 /* Data available from client. */
554 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
555 if (0 != read_from_write_to_tls(client_session, server_session)) {
556 /* EOF (or other error) */
560 /* Data available from server. */
561 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
562 if (0 != read_from_write_to_tls(server_session, client_session)) {
563 /* EOF (or other error) */
568 /* Client closed connection. */
569 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
572 /* Server closed connection. */
573 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
579 /* Read available data from session from and write to session to. */
580 static int read_from_write_to_tls(gnutls_session_t from,
581 gnutls_session_t to) {
584 ssize_t size_written;
587 /* Get maximum possible buffer size. */
588 size = gnutls_record_get_max_size(from);
589 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
591 if (size > gnutls_record_get_max_size(to)) {
592 size = gnutls_record_get_max_size(to);
594 if (size > sizeof(buffer)) {
595 size = sizeof(buffer);
597 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
600 size_read = gnutls_record_recv(from, buffer, size);
602 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
603 gnutls_strerror((int)size_read));
607 if (0 == size_read) {
611 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
612 if (0 > size_written) {
613 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
614 gnutls_strerror((int)size_written));
617 if (size_read != size_written) {
618 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
619 (long int)size_written, (long int)size_read);
627 static int connect_to_host(const char *hostname, const char *port) {
628 struct addrinfo gai_hints;
629 struct addrinfo *gai_result;
633 struct addrinfo *server;
635 if (NULL == hostname || NULL == port) {
639 /* Get IP of hostname server. */
640 memset(&gai_hints, 0, sizeof(gai_hints));
641 gai_hints.ai_family = AF_UNSPEC;
642 gai_hints.ai_socktype = SOCK_STREAM;
643 gai_hints.ai_protocol = 0;
644 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
645 | AI_ADDRCONFIG /* supported by this computer */
646 | AI_V4MAPPED; /* support IPv4 through IPv6 */
647 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
648 if (0 != gai_return) {
649 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
653 /* Now try to connect to each server returned by getaddrinfo(), use the
654 * first successful connect. */
655 for (server = gai_result; NULL != server; server = server->ai_next) {
656 server_socket = socket(server->ai_family,
658 server->ai_protocol);
659 if (-1 == server_socket) {
660 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
664 if (-1 != connect(server_socket, server->ai_addr,
665 server->ai_addrlen)) {
668 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
670 close(server_socket);
672 /* Make sure we free the result from getaddrinfo(). */
673 freeaddrinfo(gai_result);
675 if (NULL == server) {
676 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
680 return server_socket;
684 /* Parse HTTP CONNECT request string and save its parameters.
686 * The following format is expected: "CONNECT host:port HTTP/1.x".
688 * request and host must have the same size! port must be at least 6 bytes
691 static int parse_request(const char *request, char *host, char *port,
692 int *version_minor) {
693 int port_unused; /* just used to verify the port is numeric */
696 /* scanf() doesn't check spaces. */
697 if (0 != strncmp(request, "CONNECT ", 8)) {
700 /* Check request and extract data, "host:port" is not yet separated. */
701 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
702 host, version_minor)) {
705 /* Make sure ":port" is there. */
706 if (NULL == (position = strchr(host, ':'))) {
709 /* Make sure port is numeric. */
710 if (1 != sscanf(position + 1, "%d", &port_unused)) {
713 /* Store it in *port. */
714 strncpy(port, position + 1, 5);
716 /* And remove port from host. */