2 * tlsproxy is a transparent TLS proxy for HTTPS connections.
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/>.
22 /* socket(), bind(), accept(), listen() */
23 #include <sys/types.h>
24 #include <sys/socket.h>
28 #include <arpa/inet.h>
37 /* Maximum line of the request line. Longer request lines are aborted with an
38 * error. The standard doesn't specify a maximum line length but this should
39 * be a good limit to make processing simpler. */
40 #define MAX_REQUEST_LINE 4096
43 /* Proxy hostname and port if specified on the command line. */
44 static char *use_proxy_host;
45 static char *use_proxy_port;
47 static void parse_arguments(int argc, char **argv);
48 static void print_usage(const char *argv);
50 static void handle_connection(int socket);
51 static int read_http_request(FILE *client_fd, char *request, size_t length);
52 static void send_close_bad_request(FILE *client_fd);
53 static void send_close_forwarding_failure(FILE *client_fd);
55 static void transfer_data(int client, int server);
56 static int read_from_write_to(int from, int to);
58 static int connect_to_host(const char *hostname, const char *port);
60 static int parse_request(const char *buffer, char *host, char *port,
64 int main(int argc, char **argv) {
66 int client_socket, server_socket;
67 struct sockaddr_in6 server_in;
69 parse_arguments(argc, argv);
71 port = atoi(argv[argc - 1]);
72 if (0 >= port || 0xffff < port) {
74 fprintf(stderr, "\ninvalid port");
78 server_socket = socket(PF_INET6, SOCK_STREAM, 0);
79 if (-1 == server_socket) {
85 /* Fast rebinding for debug mode, could cause invalid packets. */
87 int socket_option = 1;
88 setsockopt(server_socket, SOL_SOCKET, SO_REUSEADDR,
89 &socket_option, sizeof(socket_option));
93 /* Bind to the listen socket. */
94 memset(&server_in, 0, sizeof(server_in));
95 server_in.sin6_family = AF_INET6; /* IPv6 (and IPv4) */
96 server_in.sin6_addr = in6addr_any; /* bind to any address */
97 server_in.sin6_port = htons((uint16_t)port); /* port to bind to */
98 if (-1 == bind(server_socket, (struct sockaddr *)&server_in,
103 /* And accept connections. */
104 if (-1 == listen(server_socket, 5)) {
110 printf("Listening for connections on port %d.\n", port);
112 if (NULL != use_proxy_host && NULL != use_proxy_port) {
113 printf("Using proxy: %s:%s.\n", use_proxy_host, use_proxy_port);
118 /* Accept new connection. */
119 client_socket = accept(server_socket, NULL, NULL);
120 if (-1 == client_socket) {
125 handle_connection(client_socket);
131 static void parse_arguments(int argc, char **argv) {
134 while (-1 != (option = getopt(argc, argv, "p:h?"))) {
139 /* -p must have the format host:port. */
140 if (NULL == (position = strchr(optarg, ':'))
141 || position == optarg
142 || 0 == strlen(position + 1)
143 || 0 >= atoi(position + 1)
144 || 0xffff < atoi(position + 1)) {
145 fprintf(stderr, "-p host:port\n");
149 use_proxy_host = malloc((size_t)(position - optarg) + 1);
150 if (NULL == use_proxy_host) {
154 memcpy(use_proxy_host, optarg, (size_t)(position - optarg));
155 use_proxy_host[position - optarg] = '\0';
157 use_proxy_port = malloc(strlen(position + 1) + 1);
158 if (NULL == use_proxy_port) {
162 strcpy(use_proxy_port, position + 1);
168 print_usage(argv[0]);
173 if (optind >= argc) {
174 print_usage(argv[0]);
178 static void print_usage(const char *argv) {
179 fprintf(stderr, "Usage: %s [-p host:port] port\n", argv);
180 fprintf(stderr, "\n");
181 fprintf(stderr, "-p proxy hostname and port\n");
184 static void handle_connection(int client_socket) {
186 FILE *client_fd, *server_fd;
188 char buffer[MAX_REQUEST_LINE];
189 char host[MAX_REQUEST_LINE];
195 client_fd = fdopen(client_socket, "a+");
196 if (NULL == client_fd) {
198 close(client_socket);
203 printf("New connection:\n");
206 /* Read request line (CONNECT ..) and headers (they are discarded). */
207 result = read_http_request(client_fd, buffer, sizeof(buffer));
211 } else if (result == -2) {
213 send_close_bad_request(client_fd);
218 printf(" request: %s", buffer);
221 if (0 != parse_request(buffer, host, port, &version_minor)) {
222 send_close_bad_request(client_fd);
224 printf(" bad request\n");
230 printf(" %s:%s (HTTP 1.%d)\n", host, port, version_minor);
233 /* Connect to proxy server or directly to server. */
234 if (NULL != use_proxy_host && NULL != use_proxy_port) {
235 server_socket = connect_to_host(use_proxy_host, use_proxy_port);
237 server_socket = connect_to_host(host, port);
240 if (-1 == server_socket) {
241 send_close_forwarding_failure(client_fd);
244 server_fd = fdopen(server_socket, "a+");
245 if (NULL == server_fd) {
246 send_close_forwarding_failure(client_fd);
250 /* Connect to proxy if requested (command line option). */
251 if (NULL != use_proxy_host && NULL != use_proxy_port) {
252 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
253 fprintf(server_fd, "\r\n");
255 /* Read response line from proxy server. */
256 result = read_http_request(server_fd, buffer, sizeof(buffer));
259 send_close_forwarding_failure(client_fd);
261 } else if (result == -2) {
264 send_close_forwarding_failure(client_fd);
268 /* Check response of proxy server. */
269 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
271 printf(" bad proxy response\n");
274 send_close_forwarding_failure(client_fd);
280 printf(" connection to server established\n");
283 /* We've established a connection, tell the client. */
284 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
285 fprintf(client_fd, "\r\n");
288 /* And transfer all data between client and server transparently. */
289 transfer_data(client_socket, server_socket);
295 /* Read HTTP request line and headers (ignored).
297 * On success 0 is returned, -1 on client error (we close client descriptor in
298 * this case), -2 on unexpected EOF.
300 static int read_http_request(FILE *client_fd, char *request, size_t length) {
301 char buffer[MAX_REQUEST_LINE];
303 if (NULL == fgets(request, (int)length, client_fd)) {
304 if (ferror(client_fd)) {
305 perror("fgets(), request");
313 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
315 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
319 if (ferror(client_fd)) {
320 perror("fgets(), header");
328 static void send_close_bad_request(FILE *client_fd) {
329 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
330 fprintf(client_fd, "\r\n");
333 static void send_close_forwarding_failure(FILE *client_fd) {
334 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
335 fprintf(client_fd, "\r\n");
340 /* Transfer data between client and server sockets until one closes the
342 static void transfer_data(int client, int server) {
343 struct pollfd fds[2];
345 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
348 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
352 int result = poll(fds, 2, 0);
358 /* Data available from client. */
359 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
360 if (0 != read_from_write_to(client, server)) {
361 /* EOF (or other error) */
365 /* Data available from server. */
366 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
367 if (0 != read_from_write_to(server, client)) {
368 /* EOF (or other error) */
373 /* Client closed connection. */
374 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
377 /* Server closed connection. */
378 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
384 /* Read available data from socket from and write it to socket to. At maximum
385 * 4096 bytes are read/written. */
386 static int read_from_write_to(int from, int to) {
388 ssize_t size_written;
391 size_read = read(from, buffer, sizeof(buffer));
397 if (0 == size_read) {
401 size_written = write(to, buffer, (size_t)size_read);
402 if (0 > size_written) {
406 if (size_read != size_written) {
407 printf("only written %ld of %ld bytes!\n", size_read, size_written);
415 static int connect_to_host(const char *hostname, const char *port) {
416 struct addrinfo gai_hints;
417 struct addrinfo *gai_result;
421 struct addrinfo *server;
423 if (NULL == hostname || NULL == port) {
427 /* Get IP of hostname server. */
428 memset(&gai_hints, 0, sizeof(gai_hints));
429 gai_hints.ai_family = AF_UNSPEC;
430 gai_hints.ai_socktype = SOCK_STREAM;
431 gai_hints.ai_protocol = 0;
432 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
433 | AI_ADDRCONFIG /* supported by this computer */
434 | AI_V4MAPPED; /* support IPv4 through IPv6 */
435 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
436 if (0 != gai_return) {
437 perror("getaddrinfo()");
441 /* Now try to connect to each server returned by getaddrinfo(), use the
442 * first successful connect. */
443 for (server = gai_result; NULL != server; server = server->ai_next) {
444 server_socket = socket(server->ai_family,
446 server->ai_protocol);
447 if (-1 == server_socket) {
448 perror("socket(), trying next");
452 if (-1 != connect(server_socket, server->ai_addr,
453 server->ai_addrlen)) {
456 perror("connect(), trying next");
458 close(server_socket);
460 /* Make sure we free the result from getaddrinfo(). */
461 freeaddrinfo(gai_result);
463 if (NULL == server) {
464 fprintf(stderr, "no server found, aborting\n");
468 return server_socket;
472 /* Parse HTTP CONNECT request string and save its parameters.
474 * The following format is expected: "CONNECT host:port HTTP/1.y".
476 * request and host must have the same size! port must be at least 6 bytes
479 static int parse_request(const char *request, char *host, char *port,
480 int *version_minor) {
481 int port_unused; /* just used to verify the port is numeric */
484 /* scanf() doesn't check spaces. */
485 if (0 != strncmp(request, "CONNECT ", 8)) {
488 /* Check request and extract data, "host:port" is not yet separated. */
489 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
490 host, version_minor)) {
493 /* Make sure ":port" is there. */
494 if (NULL == (position = strchr(host, ':'))) {
497 /* Make sure port is numeric. */
498 if (1 != sscanf(position + 1, "%d", &port_unused)) {
501 /* Store it in *port. */
502 strncpy(port, position + 1, 5);
504 /* And remove port from host. */