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. Use GNUTLS_SHUT_RDWR so the data is
241 * reliable transmitted. */
242 if (0 != server_session_started) {
243 gnutls_bye(server_session, GNUTLS_SHUT_RDWR);
245 if (0 != client_session_started) {
246 gnutls_bye(client_session, GNUTLS_SHUT_RDWR);
248 if (0 != server_session_init) {
249 gnutls_deinit(server_session);
250 gnutls_certificate_free_credentials(server_x509_cred);
252 if (0 != client_session_init) {
253 gnutls_deinit(client_session);
254 gnutls_certificate_free_cas(client_x509_cred);
255 gnutls_certificate_free_keys(client_x509_cred);
256 gnutls_certificate_free_credentials(client_x509_cred);
259 /* Close connection to server/proxy. */
260 if (NULL != server_fd) {
262 } else if (-1 != server_socket) {
263 close(server_socket);
265 LOG(LOG_DEBUG, "connection to server closed");
266 /* Close connection to client. */
267 if (NULL != client_fd) {
270 close(client_socket);
272 LOG(LOG_DEBUG, "connection to client closed");
274 LOG(LOG_DEBUG, "connection finished");
278 static int initialize_tls_session_client(int peer_socket,
279 const char *hostname,
280 gnutls_session_t *session,
281 gnutls_certificate_credentials_t *x509_cred) {
285 /* Hostname too long. */
286 if (sizeof(path) - strlen(PROXY_SERVER_CERT_FORMAT) <= strlen(hostname)) {
288 "initialize_tls_session_client(): hostname too long: '%s'",
292 /* Try to prevent path traversals in hostnames. */
293 if (NULL != strstr(hostname, "..")) {
295 "initialize_tls_session_client(): possible path traversal: '%s'",
299 snprintf(path, sizeof(path), PROXY_SERVER_CERT_FORMAT, hostname);
301 result = gnutls_certificate_allocate_credentials(x509_cred);
302 if (GNUTLS_E_SUCCESS != result) {
304 "initialize_tls_session_client(): \
305 gnutls_certificate_allocate_credentials(): %s",
306 gnutls_strerror(result));
310 /* Load proxy CA file, this CA "list" is send to the client. */
311 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
313 GNUTLS_X509_FMT_PEM);
316 "initialize_tls_session_client(): can't read CA file: '%s'",
320 /* And certificate for this website and proxy's private key. */
321 result = gnutls_certificate_set_x509_key_file(*x509_cred,
322 path, PROXY_KEY_FILE,
323 GNUTLS_X509_FMT_PEM);
324 if (GNUTLS_E_SUCCESS != result) {
326 "initialize_tls_session_client(): \
327 can't read server certificate ('%s') or key file ('%s'): %s",
328 path, PROXY_KEY_FILE, gnutls_strerror(result));
329 /* Could be a missing certificate. */
333 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
335 result = gnutls_init(session, GNUTLS_SERVER);
336 if (GNUTLS_E_SUCCESS != result) {
338 "initialize_tls_session_client(): gnutls_init(): %s",
339 gnutls_strerror(result));
342 result = gnutls_priority_set(*session, tls_priority_cache);
343 if (GNUTLS_E_SUCCESS != result) {
345 "initialize_tls_session_client(): gnutls_priority_set(): %s",
346 gnutls_strerror(result));
349 result = gnutls_credentials_set(*session,
350 GNUTLS_CRD_CERTIFICATE, *x509_cred);
351 if (GNUTLS_E_SUCCESS != result) {
353 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
354 gnutls_strerror(result));
358 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
362 static int initialize_tls_session_server(int peer_socket,
363 gnutls_session_t *session,
364 gnutls_certificate_credentials_t *x509_cred) {
367 result = gnutls_certificate_allocate_credentials(x509_cred);
368 if (GNUTLS_E_SUCCESS != result) {
370 "initialize_tls_session_server(): \
371 gnutls_certificate_allocate_credentials(): %s",
372 gnutls_strerror(result));
376 result = gnutls_init(session, GNUTLS_CLIENT);
377 if (GNUTLS_E_SUCCESS != result) {
379 "initialize_tls_session_server(): gnutls_init(): %s",
380 gnutls_strerror(result));
383 gnutls_priority_set(*session, tls_priority_cache);
384 if (GNUTLS_E_SUCCESS != result) {
386 "initialize_tls_session_server(): gnutls_priority_set(): %s",
387 gnutls_strerror(result));
390 result = gnutls_credentials_set(*session,
391 GNUTLS_CRD_CERTIFICATE, *x509_cred);
392 if (GNUTLS_E_SUCCESS != result) {
394 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
395 gnutls_strerror(result));
399 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
405 /* Read HTTP request line and headers (ignored).
407 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
409 static int read_http_request(FILE *client_fd, char *request, size_t length) {
410 char buffer[MAX_REQUEST_LINE];
412 if (NULL == fgets(request, (int)length, client_fd)) {
413 if (ferror(client_fd)) {
414 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
421 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
423 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
427 if (ferror(client_fd)) {
428 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
435 static void send_bad_request(FILE *client_fd) {
436 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
437 fprintf(client_fd, "\r\n");
439 static void send_forwarding_failure(FILE *client_fd) {
440 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
441 fprintf(client_fd, "\r\n");
446 /* Transfer data between client and server sockets until one closes the
448 static void transfer_data(int client, int server) {
449 struct pollfd fds[2];
451 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
454 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
458 int result = poll(fds, 2, -1 /* no timeout */);
460 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
464 /* Data available from client. */
465 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
466 if (0 != read_from_write_to(client, server)) {
467 /* EOF (or other error) */
471 /* Data available from server. */
472 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
473 if (0 != read_from_write_to(server, client)) {
474 /* EOF (or other error) */
479 /* Client closed connection. */
480 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
483 /* Server closed connection. */
484 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
490 /* Read available data from socket from and write it to socket to. At maximum
491 * 4096 bytes are read/written. */
492 static int read_from_write_to(int from, int to) {
494 ssize_t size_written;
497 size_read = read(from, buffer, sizeof(buffer));
499 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
503 if (0 == size_read) {
507 size_written = write(to, buffer, (size_t)size_read);
508 if (0 > size_written) {
509 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
512 if (size_read != size_written) {
513 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
514 (long int)size_written, (long int)size_read);
522 /* Transfer data between client and server TLS connection until one closes the
524 static void transfer_data_tls(int client, int server,
525 gnutls_session_t client_session,
526 gnutls_session_t server_session) {
527 struct pollfd fds[2];
529 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
532 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
536 int result = poll(fds, 2, -1 /* no timeout */);
538 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
542 /* Data available from client. */
543 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
544 if (0 != read_from_write_to_tls(client_session, server_session)) {
545 /* EOF (or other error) */
549 /* Data available from server. */
550 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
551 if (0 != read_from_write_to_tls(server_session, client_session)) {
552 /* EOF (or other error) */
557 /* Client closed connection. */
558 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
561 /* Server closed connection. */
562 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
568 /* Read available data from session from and write to session to. */
569 static int read_from_write_to_tls(gnutls_session_t from,
570 gnutls_session_t to) {
573 ssize_t size_written;
576 /* Get maximum possible buffer size. */
577 size = gnutls_record_get_max_size(from);
578 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
580 if (size > gnutls_record_get_max_size(to)) {
581 size = gnutls_record_get_max_size(to);
583 if (size > sizeof(buffer)) {
584 size = sizeof(buffer);
586 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
589 size_read = gnutls_record_recv(from, buffer, size);
591 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
592 gnutls_strerror((int)size_read));
596 if (0 == size_read) {
600 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
601 if (0 > size_written) {
602 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
603 gnutls_strerror((int)size_written));
606 if (size_read != size_written) {
607 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
608 (long int)size_written, (long int)size_read);
616 static int connect_to_host(const char *hostname, const char *port) {
617 struct addrinfo gai_hints;
618 struct addrinfo *gai_result;
622 struct addrinfo *server;
624 if (NULL == hostname || NULL == port) {
628 /* Get IP of hostname server. */
629 memset(&gai_hints, 0, sizeof(gai_hints));
630 gai_hints.ai_family = AF_UNSPEC;
631 gai_hints.ai_socktype = SOCK_STREAM;
632 gai_hints.ai_protocol = 0;
633 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
634 | AI_ADDRCONFIG /* supported by this computer */
635 | AI_V4MAPPED; /* support IPv4 through IPv6 */
636 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
637 if (0 != gai_return) {
638 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
642 /* Now try to connect to each server returned by getaddrinfo(), use the
643 * first successful connect. */
644 for (server = gai_result; NULL != server; server = server->ai_next) {
645 server_socket = socket(server->ai_family,
647 server->ai_protocol);
648 if (-1 == server_socket) {
649 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
653 if (-1 != connect(server_socket, server->ai_addr,
654 server->ai_addrlen)) {
657 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
659 close(server_socket);
661 /* Make sure we free the result from getaddrinfo(). */
662 freeaddrinfo(gai_result);
664 if (NULL == server) {
665 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
669 return server_socket;
673 /* Parse HTTP CONNECT request string and save its parameters.
675 * The following format is expected: "CONNECT host:port HTTP/1.x".
677 * request and host must have the same size! port must be at least 6 bytes
680 static int parse_request(const char *request, char *host, char *port,
681 int *version_minor) {
682 int port_unused; /* just used to verify the port is numeric */
685 /* scanf() doesn't check spaces. */
686 if (0 != strncmp(request, "CONNECT ", 8)) {
689 /* Check request and extract data, "host:port" is not yet separated. */
690 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
691 host, version_minor)) {
694 /* Make sure ":port" is there. */
695 if (NULL == (position = strchr(host, ':'))) {
698 /* Make sure port is numeric. */
699 if (1 != sscanf(position + 1, "%d", &port_unused)) {
702 /* Store it in *port. */
703 strncpy(port, position + 1, 5);
705 /* And remove port from host. */