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"
37 /* Maximum line of a HTTP request line. Longer request lines are aborted with
38 * an error. The standard doesn't specify a maximum line length but this
39 * should be a good limit to make processing simpler. */
40 #define MAX_REQUEST_LINE 4096
42 /* Paths to necessary TLS files: the CA and the server key. */
43 #define PROXY_CA_FILE "proxy-ca.pem"
44 #define PROXY_KEY_FILE "proxy-key.pem"
46 /* Helper macro for LOG/LOG_PERROR. Print file/line number if compiled with
49 #define LOG_PRINT_LOCATION fprintf(stdout, "%s:%-3d ", __FILE__, __LINE__);
51 #define LOG_PRINT_LOCATION
53 /* Call log_message() and print current file and line number. */
57 /* perror() replacement with debug level support. */
58 #define LOG_PERROR(level, message) \
60 log_message(level, "%s: %s", message, strerror(errno))
63 static int initialize_tls_session_client(int peer_socket,
65 gnutls_session_t *session,
66 gnutls_certificate_credentials_t *x509_cred);
67 static int initialize_tls_session_server(int peer_socket,
68 gnutls_session_t *session,
69 gnutls_certificate_credentials_t *x509_cred);
71 static int read_http_request(FILE *client_fd, char *request, size_t length);
72 static void send_bad_request(FILE *client_fd);
73 static void send_forwarding_failure(FILE *client_fd);
76 static void transfer_data(int client, int server);
77 static int read_from_write_to(int from, int to);
79 static void transfer_data_tls(int client, int server,
80 gnutls_session_t client_session,
81 gnutls_session_t server_session);
82 static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to);
84 static int connect_to_host(const char *hostname, const char *port);
86 static int parse_request(const char *buffer, char *host, char *port,
89 static void log_message(int level, const char *format, ...);
92 void handle_connection(int client_socket) {
94 FILE *client_fd, *server_fd;
96 char buffer[MAX_REQUEST_LINE];
97 char host[MAX_REQUEST_LINE];
103 /* client_x509_cred is used when talking to the client (acting as a TSL
104 * server), server_x509_cred is used when talking to the server (acting as
106 gnutls_certificate_credentials_t client_x509_cred, server_x509_cred;
108 gnutls_session_t client_session, server_session;
109 /* initialize_tls_session_*() called? - used for goto out */
110 int client_session_init, server_session_init;
111 /* gnutls_handshake() called? - used for goto out */
112 int client_session_started, server_session_started;
114 LOG(LOG_DEBUG, "new connection");
119 client_session_init = 0;
120 server_session_init = 0;
121 client_session_started = 0;
122 server_session_started = 0;
124 client_fd = fdopen(client_socket, "a+");
125 if (NULL == client_fd) {
126 LOG_PERROR(LOG_WARNING, "fdopen(): client failed");
130 /* Read request line (CONNECT ..) and headers (they are discarded). */
131 result = read_http_request(client_fd, buffer, sizeof(buffer));
134 LOG(LOG_WARNING, "read_http_request(): client read error");
136 } else if (-2 == result) {
138 LOG(LOG_WARNING, "read_http_request(): client EOF");
139 send_bad_request(client_fd);
143 if (0 != parse_request(buffer, host, port, &version_minor)) {
144 LOG(LOG_WARNING, "bad request: %s", buffer);
145 send_bad_request(client_fd);
149 LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
151 /* Connect to proxy server or directly to server. */
152 if (NULL != global_proxy_host && NULL != global_proxy_port) {
153 LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host,
155 server_socket = connect_to_host(global_proxy_host, global_proxy_port);
157 LOG(LOG_DEBUG, "connecting to %s:%s", host, port);
158 server_socket = connect_to_host(host, port);
161 if (-1 == server_socket) {
162 LOG(LOG_WARNING, "failed to connect to server");
163 send_forwarding_failure(client_fd);
166 server_fd = fdopen(server_socket, "a+");
167 if (NULL == server_fd) {
168 LOG_PERROR(LOG_WARNING, "fdopen(): server failed");
169 send_forwarding_failure(client_fd);
173 /* Connect to proxy if requested (command line option). */
174 if (NULL != global_proxy_host && NULL != global_proxy_port) {
175 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
176 fprintf(server_fd, "\r\n");
178 /* Read response line from proxy server. */
179 result = read_http_request(server_fd, buffer, sizeof(buffer));
182 LOG(LOG_WARNING, "read_http_request(): proxy read error");
183 send_forwarding_failure(client_fd);
185 } else if (-2 == result) {
187 LOG(LOG_WARNING, "read_http_request(): proxy EOF");
188 send_forwarding_failure(client_fd);
192 /* Check response of proxy server. */
193 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
194 LOG(LOG_WARNING, "bad proxy response: %s", buffer);
195 send_forwarding_failure(client_fd);
200 LOG(LOG_DEBUG, "connection to server established");
202 /* We've established a connection, tell the client. */
203 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
204 fprintf(client_fd, "\r\n");
207 /* Initialize TLS server credentials to talk to the client. */
208 result = initialize_tls_session_client(client_socket, host,
212 LOG(LOG_WARNING, "initialize_tls_session_client() failed");
213 send_forwarding_failure(client_fd);
216 client_session_init = 1;
218 LOG(LOG_DEBUG, "starting client TLS handshake");
220 /* Try to establish TLS handshake between client and us. */
221 result = gnutls_handshake(client_session);
222 if (GNUTLS_E_SUCCESS != result) {
223 LOG(LOG_WARNING, "client TLS handshake failed: %s",
224 gnutls_strerror(result));
225 send_forwarding_failure(client_fd);
228 client_session_started = 1;
230 LOG(LOG_DEBUG, "client TLS handshake finished");
232 result = initialize_tls_session_server(server_socket, &server_session,
234 /* Initialize TLS client credentials to talk to the server. */
236 LOG(LOG_WARNING, "initialize_tls_session_server() failed");
237 send_forwarding_failure(client_fd);
240 server_session_init = 1;
242 LOG(LOG_DEBUG, "starting server TLS handshake");
244 /* Try to establish TLS handshake between us and server. */
245 result = gnutls_handshake(server_session);
246 if (GNUTLS_E_SUCCESS != result) {
247 LOG(LOG_WARNING, "server TLS handshake failed: %s",
248 gnutls_strerror(result));
249 send_forwarding_failure(client_fd);
252 server_session_started = 1;
254 LOG(LOG_DEBUG, "server TLS handshake finished, transferring data");
256 /* FIXME: verify server's fingerprint */
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. */
267 if (0 != server_session_started) {
268 gnutls_bye(server_session, GNUTLS_SHUT_WR);
270 if (0 != client_session_started) {
271 gnutls_bye(client_session, GNUTLS_SHUT_WR);
273 if (0 != server_session_init) {
274 gnutls_deinit(server_session);
275 gnutls_certificate_free_credentials(server_x509_cred);
277 if (0 != client_session_init) {
278 gnutls_deinit(client_session);
279 gnutls_certificate_free_cas(client_x509_cred);
280 gnutls_certificate_free_keys(client_x509_cred);
281 gnutls_certificate_free_credentials(client_x509_cred);
284 /* Close connection to server/proxy. */
285 if (NULL != server_fd) {
287 } else if (-1 != server_socket) {
288 close(server_socket);
290 LOG(LOG_DEBUG, "connection to server closed");
291 /* Close connection to client. */
292 if (NULL != client_fd) {
295 close(client_socket);
297 LOG(LOG_DEBUG, "connection to client closed");
299 LOG(LOG_DEBUG, "connection finished");
303 static int initialize_tls_session_client(int peer_socket,
304 const char *hostname,
305 gnutls_session_t *session,
306 gnutls_certificate_credentials_t *x509_cred) {
309 /* The server certificate for the given hostname is stored in
310 * "./certificate-hostname-proxy.pem". */
311 #define PATH_FORMAT "./certificate-%s-proxy.pem"
313 /* Hostname too long. */
314 if (sizeof(path) - strlen(PATH_FORMAT) <= strlen(hostname)) {
316 "initialize_tls_session_client(): hostname too long: '%s'",
320 /* Try to prevent path traversals in hostnames. */
321 if (NULL != strstr(hostname, "..")) {
323 "initialize_tls_session_client(): possible path traversal: '%s'",
327 snprintf(path, sizeof(path), PATH_FORMAT, hostname);
330 result = gnutls_certificate_allocate_credentials(x509_cred);
331 if (GNUTLS_E_SUCCESS != result) {
333 "initialize_tls_session_client(): \
334 gnutls_certificate_allocate_credentials(): %s",
335 gnutls_strerror(result));
339 /* Load proxy CA file, this CA "list" is send to the client. */
340 result = gnutls_certificate_set_x509_trust_file(*x509_cred,
342 GNUTLS_X509_FMT_PEM);
345 "initialize_tls_session_client(): can't read CA file: '%s'",
349 /* And certificate for this website and proxy's private key. */
350 result = gnutls_certificate_set_x509_key_file(*x509_cred,
351 path, PROXY_KEY_FILE,
352 GNUTLS_X509_FMT_PEM);
353 if (GNUTLS_E_SUCCESS != result) {
355 "initialize_tls_session_client(): \
356 can't read server certificate ('%s') or key file ('%s'): %s",
357 path, PROXY_KEY_FILE, gnutls_strerror(result));
358 /* Could be a missing certificate. */
362 gnutls_certificate_set_dh_params(*x509_cred, tls_dh_params);
364 result = gnutls_init(session, GNUTLS_SERVER);
365 if (GNUTLS_E_SUCCESS != result) {
367 "initialize_tls_session_client(): gnutls_init(): %s",
368 gnutls_strerror(result));
371 result = gnutls_priority_set(*session, tls_priority_cache);
372 if (GNUTLS_E_SUCCESS != result) {
374 "initialize_tls_session_client(): gnutls_priority_set(): %s",
375 gnutls_strerror(result));
378 result = gnutls_credentials_set(*session,
379 GNUTLS_CRD_CERTIFICATE, *x509_cred);
380 if (GNUTLS_E_SUCCESS != result) {
382 "initialize_tls_session_client(): gnutls_credentials_set(): %s",
383 gnutls_strerror(result));
387 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
391 static int initialize_tls_session_server(int peer_socket,
392 gnutls_session_t *session,
393 gnutls_certificate_credentials_t *x509_cred) {
396 result = gnutls_certificate_allocate_credentials(x509_cred);
397 if (GNUTLS_E_SUCCESS != result) {
399 "initialize_tls_session_server(): \
400 gnutls_certificate_allocate_credentials(): %s",
401 gnutls_strerror(result));
405 result = gnutls_init(session, GNUTLS_CLIENT);
406 if (GNUTLS_E_SUCCESS != result) {
408 "initialize_tls_session_server(): gnutls_init(): %s",
409 gnutls_strerror(result));
412 gnutls_priority_set(*session, tls_priority_cache);
413 if (GNUTLS_E_SUCCESS != result) {
415 "initialize_tls_session_server(): gnutls_priority_set(): %s",
416 gnutls_strerror(result));
419 result = gnutls_credentials_set(*session,
420 GNUTLS_CRD_CERTIFICATE, *x509_cred);
421 if (GNUTLS_E_SUCCESS != result) {
423 "initialize_tls_session_server(): gnutls_credentials_set(): %s",
424 gnutls_strerror(result));
428 gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
434 /* Read HTTP request line and headers (ignored).
436 * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
438 static int read_http_request(FILE *client_fd, char *request, size_t length) {
439 char buffer[MAX_REQUEST_LINE];
441 if (NULL == fgets(request, (int)length, client_fd)) {
442 if (ferror(client_fd)) {
443 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
450 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
452 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
456 if (ferror(client_fd)) {
457 LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()");
464 static void send_bad_request(FILE *client_fd) {
465 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
466 fprintf(client_fd, "\r\n");
468 static void send_forwarding_failure(FILE *client_fd) {
469 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
470 fprintf(client_fd, "\r\n");
475 /* Transfer data between client and server sockets until one closes the
477 static void transfer_data(int client, int server) {
478 struct pollfd fds[2];
480 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
483 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
487 int result = poll(fds, 2, -1 /* no timeout */);
489 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
493 /* Data available from client. */
494 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
495 if (0 != read_from_write_to(client, server)) {
496 /* EOF (or other error) */
500 /* Data available from server. */
501 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
502 if (0 != read_from_write_to(server, client)) {
503 /* EOF (or other error) */
508 /* Client closed connection. */
509 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
512 /* Server closed connection. */
513 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
519 /* Read available data from socket from and write it to socket to. At maximum
520 * 4096 bytes are read/written. */
521 static int read_from_write_to(int from, int to) {
523 ssize_t size_written;
526 size_read = read(from, buffer, sizeof(buffer));
528 LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()");
532 if (0 == size_read) {
536 size_written = write(to, buffer, (size_t)size_read);
537 if (0 > size_written) {
538 LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()");
541 if (size_read != size_written) {
542 LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
543 (long int)size_written, (long int)size_read);
551 /* Transfer data between client and server TLS connection until one closes the
553 static void transfer_data_tls(int client, int server,
554 gnutls_session_t client_session,
555 gnutls_session_t server_session) {
556 struct pollfd fds[2];
558 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
561 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
565 int result = poll(fds, 2, -1 /* no timeout */);
567 LOG_PERROR(LOG_ERROR, "transfer_data(): poll()");
571 /* Data available from client. */
572 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
573 if (0 != read_from_write_to_tls(client_session, server_session)) {
574 /* EOF (or other error) */
578 /* Data available from server. */
579 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
580 if (0 != read_from_write_to_tls(server_session, client_session)) {
581 /* EOF (or other error) */
586 /* Client closed connection. */
587 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
590 /* Server closed connection. */
591 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
597 /* Read available data from session from and write to session to. */
598 static int read_from_write_to_tls(gnutls_session_t from,
599 gnutls_session_t to) {
602 ssize_t size_written;
605 /* Get maximum possible buffer size. */
606 size = gnutls_record_get_max_size(from);
607 LOG(LOG_DEBUG, "read_from_write_to_tls(): suggested buffer size: %ld",
609 if (size > gnutls_record_get_max_size(to)) {
610 size = gnutls_record_get_max_size(to);
612 if (size > sizeof(buffer)) {
613 size = sizeof(buffer);
615 LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld",
618 size_read = gnutls_record_recv(from, buffer, size);
620 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
621 gnutls_strerror((int)size_read));
625 if (0 == size_read) {
629 size_written = gnutls_record_send(to, buffer, (size_t)size_read);
630 if (0 > size_written) {
631 LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
632 gnutls_strerror((int)size_written));
635 if (size_read != size_written) {
636 LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
637 (long int)size_written, (long int)size_read);
645 static int connect_to_host(const char *hostname, const char *port) {
646 struct addrinfo gai_hints;
647 struct addrinfo *gai_result;
651 struct addrinfo *server;
653 if (NULL == hostname || NULL == port) {
657 /* Get IP of hostname server. */
658 memset(&gai_hints, 0, sizeof(gai_hints));
659 gai_hints.ai_family = AF_UNSPEC;
660 gai_hints.ai_socktype = SOCK_STREAM;
661 gai_hints.ai_protocol = 0;
662 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
663 | AI_ADDRCONFIG /* supported by this computer */
664 | AI_V4MAPPED; /* support IPv4 through IPv6 */
665 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
666 if (0 != gai_return) {
667 LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()");
671 /* Now try to connect to each server returned by getaddrinfo(), use the
672 * first successful connect. */
673 for (server = gai_result; NULL != server; server = server->ai_next) {
674 server_socket = socket(server->ai_family,
676 server->ai_protocol);
677 if (-1 == server_socket) {
678 LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next");
682 if (-1 != connect(server_socket, server->ai_addr,
683 server->ai_addrlen)) {
686 LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next");
688 close(server_socket);
690 /* Make sure we free the result from getaddrinfo(). */
691 freeaddrinfo(gai_result);
693 if (NULL == server) {
694 LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort");
698 return server_socket;
702 /* Parse HTTP CONNECT request string and save its parameters.
704 * The following format is expected: "CONNECT host:port HTTP/1.x".
706 * request and host must have the same size! port must be at least 6 bytes
709 static int parse_request(const char *request, char *host, char *port,
710 int *version_minor) {
711 int port_unused; /* just used to verify the port is numeric */
714 /* scanf() doesn't check spaces. */
715 if (0 != strncmp(request, "CONNECT ", 8)) {
718 /* Check request and extract data, "host:port" is not yet separated. */
719 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
720 host, version_minor)) {
723 /* Make sure ":port" is there. */
724 if (NULL == (position = strchr(host, ':'))) {
727 /* Make sure port is numeric. */
728 if (1 != sscanf(position + 1, "%d", &port_unused)) {
731 /* Store it in *port. */
732 strncpy(port, position + 1, 5);
734 /* And remove port from host. */
741 static void log_message(int level, const char *format, ...) {
743 const char *level_string;
745 if (global_log_level < level) {
750 case LOG_ERROR: level_string = "ERROR"; break;
751 case LOG_WARNING: level_string = "WARN "; break;
752 case LOG_DEBUG: level_string = "DEBUG"; break;
753 default: level_string = "UNKNOWN";
756 va_start(ap, format);
757 fprintf(stdout, "[%s] [%d] ", level_string, (int)pthread_self());
758 vfprintf(stdout, format, ap);
759 fprintf(stdout, "\n");