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>
39 /* Maximum line of the request line. Longer request lines are aborted with an
40 * error. The standard doesn't specify a maximum line length but this should
41 * be a good limit to make processing simpler. */
42 #define MAX_REQUEST_LINE 4096
45 /* Server should shut down. Set by SIGINT handler. */
46 static volatile int done;
48 /* Proxy hostname and port if specified on the command line. */
49 static char *use_proxy_host;
50 static char *use_proxy_port;
53 static void sigint_handler(int signal);
55 static void parse_arguments(int argc, char **argv);
56 static void print_usage(const char *argv);
58 static void handle_connection(int socket);
59 static int read_http_request(FILE *client_fd, char *request, size_t length);
60 static void send_close_bad_request(FILE *client_fd);
61 static void send_close_forwarding_failure(FILE *client_fd);
63 static void transfer_data(int client, int server);
64 static int read_from_write_to(int from, int to);
66 static int connect_to_host(const char *hostname, const char *port);
68 static int parse_request(const char *buffer, char *host, char *port,
72 int main(int argc, char **argv) {
74 int client_socket, server_socket;
75 struct sockaddr_in6 server_in;
77 struct sigaction action;
79 parse_arguments(argc, argv);
81 port = atoi(argv[argc - 1]);
82 if (0 >= port || 0xffff < port) {
84 fprintf(stderr, "\ninvalid port");
88 /* Setup our SIGINT signal handler which allows a "normal" termination of
90 sigemptyset(&action.sa_mask);
91 action.sa_handler = sigint_handler;
93 sigaction(SIGINT, &action, NULL);
95 server_socket = socket(PF_INET6, SOCK_STREAM, 0);
96 if (-1 == server_socket) {
102 /* Fast rebinding for debug mode, could cause invalid packets. */
104 int socket_option = 1;
105 setsockopt(server_socket, SOL_SOCKET, SO_REUSEADDR,
106 &socket_option, sizeof(socket_option));
110 /* Bind to the listen socket. */
111 memset(&server_in, 0, sizeof(server_in));
112 server_in.sin6_family = AF_INET6; /* IPv6 (and IPv4) */
113 server_in.sin6_addr = in6addr_any; /* bind to any address */
114 server_in.sin6_port = htons((uint16_t)port); /* port to bind to */
115 if (-1 == bind(server_socket, (struct sockaddr *)&server_in,
116 sizeof(server_in))) {
120 /* And accept connections. */
121 if (-1 == listen(server_socket, 5)) {
127 printf("Listening for connections on port %d.\n", port);
129 if (NULL != use_proxy_host && NULL != use_proxy_port) {
130 printf("Using proxy: %s:%s.\n", use_proxy_host, use_proxy_port);
135 /* Accept new connection. */
136 client_socket = accept(server_socket, NULL, NULL);
137 if (-1 == client_socket) {
142 handle_connection(client_socket);
145 close(server_socket);
147 free(use_proxy_host);
148 free(use_proxy_port);
153 static void sigint_handler(int signal_number) {
159 static void parse_arguments(int argc, char **argv) {
162 while (-1 != (option = getopt(argc, argv, "p:h?"))) {
167 /* -p must have the format host:port. */
168 if (NULL == (position = strchr(optarg, ':'))
169 || position == optarg
170 || 0 == strlen(position + 1)
171 || 0 >= atoi(position + 1)
172 || 0xffff < atoi(position + 1)) {
173 fprintf(stderr, "-p host:port\n");
177 use_proxy_host = malloc((size_t)(position - optarg) + 1);
178 if (NULL == use_proxy_host) {
182 memcpy(use_proxy_host, optarg, (size_t)(position - optarg));
183 use_proxy_host[position - optarg] = '\0';
185 use_proxy_port = malloc(strlen(position + 1) + 1);
186 if (NULL == use_proxy_port) {
190 strcpy(use_proxy_port, position + 1);
196 print_usage(argv[0]);
201 if (optind >= argc) {
202 print_usage(argv[0]);
206 static void print_usage(const char *argv) {
207 fprintf(stderr, "Usage: %s [-p host:port] port\n", argv);
208 fprintf(stderr, "\n");
209 fprintf(stderr, "-p proxy hostname and port\n");
212 static void handle_connection(int client_socket) {
214 FILE *client_fd, *server_fd;
216 char buffer[MAX_REQUEST_LINE];
217 char host[MAX_REQUEST_LINE];
223 client_fd = fdopen(client_socket, "a+");
224 if (NULL == client_fd) {
226 close(client_socket);
231 printf("New connection:\n");
234 /* Read request line (CONNECT ..) and headers (they are discarded). */
235 result = read_http_request(client_fd, buffer, sizeof(buffer));
239 } else if (result == -2) {
241 send_close_bad_request(client_fd);
246 printf(" request: %s", buffer);
249 if (0 != parse_request(buffer, host, port, &version_minor)) {
250 send_close_bad_request(client_fd);
252 printf(" bad request\n");
258 printf(" %s:%s (HTTP 1.%d)\n", host, port, version_minor);
261 /* Connect to proxy server or directly to server. */
262 if (NULL != use_proxy_host && NULL != use_proxy_port) {
263 server_socket = connect_to_host(use_proxy_host, use_proxy_port);
265 server_socket = connect_to_host(host, port);
268 if (-1 == server_socket) {
269 send_close_forwarding_failure(client_fd);
272 server_fd = fdopen(server_socket, "a+");
273 if (NULL == server_fd) {
274 send_close_forwarding_failure(client_fd);
278 /* Connect to proxy if requested (command line option). */
279 if (NULL != use_proxy_host && NULL != use_proxy_port) {
280 fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
281 fprintf(server_fd, "\r\n");
283 /* Read response line from proxy server. */
284 result = read_http_request(server_fd, buffer, sizeof(buffer));
287 send_close_forwarding_failure(client_fd);
289 } else if (result == -2) {
292 send_close_forwarding_failure(client_fd);
296 /* Check response of proxy server. */
297 if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) {
299 printf(" bad proxy response\n");
302 send_close_forwarding_failure(client_fd);
308 printf(" connection to server established\n");
311 /* We've established a connection, tell the client. */
312 fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n");
313 fprintf(client_fd, "\r\n");
316 /* And transfer all data between client and server transparently. */
317 transfer_data(client_socket, server_socket);
323 /* Read HTTP request line and headers (ignored).
325 * On success 0 is returned, -1 on client error (we close client descriptor in
326 * this case), -2 on unexpected EOF.
328 static int read_http_request(FILE *client_fd, char *request, size_t length) {
329 char buffer[MAX_REQUEST_LINE];
331 if (NULL == fgets(request, (int)length, client_fd)) {
332 if (ferror(client_fd)) {
333 perror("fgets(), request");
341 while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
343 if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
347 if (ferror(client_fd)) {
348 perror("fgets(), header");
356 static void send_close_bad_request(FILE *client_fd) {
357 fprintf(client_fd, "HTTP/1.0 400 Bad Request\r\n");
358 fprintf(client_fd, "\r\n");
361 static void send_close_forwarding_failure(FILE *client_fd) {
362 fprintf(client_fd, "HTTP/1.0 503 Forwarding failure\r\n");
363 fprintf(client_fd, "\r\n");
368 /* Transfer data between client and server sockets until one closes the
370 static void transfer_data(int client, int server) {
371 struct pollfd fds[2];
373 fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
376 fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR;
380 int result = poll(fds, 2, 0);
386 /* Data available from client. */
387 if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
388 if (0 != read_from_write_to(client, server)) {
389 /* EOF (or other error) */
393 /* Data available from server. */
394 if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
395 if (0 != read_from_write_to(server, client)) {
396 /* EOF (or other error) */
401 /* Client closed connection. */
402 if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
405 /* Server closed connection. */
406 if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
412 /* Read available data from socket from and write it to socket to. At maximum
413 * 4096 bytes are read/written. */
414 static int read_from_write_to(int from, int to) {
416 ssize_t size_written;
419 size_read = read(from, buffer, sizeof(buffer));
425 if (0 == size_read) {
429 size_written = write(to, buffer, (size_t)size_read);
430 if (0 > size_written) {
434 if (size_read != size_written) {
435 printf("only written %ld of %ld bytes!\n", size_read, size_written);
443 static int connect_to_host(const char *hostname, const char *port) {
444 struct addrinfo gai_hints;
445 struct addrinfo *gai_result;
449 struct addrinfo *server;
451 if (NULL == hostname || NULL == port) {
455 /* Get IP of hostname server. */
456 memset(&gai_hints, 0, sizeof(gai_hints));
457 gai_hints.ai_family = AF_UNSPEC;
458 gai_hints.ai_socktype = SOCK_STREAM;
459 gai_hints.ai_protocol = 0;
460 gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */
461 | AI_ADDRCONFIG /* supported by this computer */
462 | AI_V4MAPPED; /* support IPv4 through IPv6 */
463 gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
464 if (0 != gai_return) {
465 perror("getaddrinfo()");
469 /* Now try to connect to each server returned by getaddrinfo(), use the
470 * first successful connect. */
471 for (server = gai_result; NULL != server; server = server->ai_next) {
472 server_socket = socket(server->ai_family,
474 server->ai_protocol);
475 if (-1 == server_socket) {
476 perror("socket(), trying next");
480 if (-1 != connect(server_socket, server->ai_addr,
481 server->ai_addrlen)) {
484 perror("connect(), trying next");
486 close(server_socket);
488 /* Make sure we free the result from getaddrinfo(). */
489 freeaddrinfo(gai_result);
491 if (NULL == server) {
492 fprintf(stderr, "no server found, aborting\n");
496 return server_socket;
500 /* Parse HTTP CONNECT request string and save its parameters.
502 * The following format is expected: "CONNECT host:port HTTP/1.y".
504 * request and host must have the same size! port must be at least 6 bytes
507 static int parse_request(const char *request, char *host, char *port,
508 int *version_minor) {
509 int port_unused; /* just used to verify the port is numeric */
512 /* scanf() doesn't check spaces. */
513 if (0 != strncmp(request, "CONNECT ", 8)) {
516 /* Check request and extract data, "host:port" is not yet separated. */
517 if (2 != sscanf(request, "CONNECT %s HTTP/1.%d",
518 host, version_minor)) {
521 /* Make sure ":port" is there. */
522 if (NULL == (position = strchr(host, ':'))) {
525 /* Make sure port is numeric. */
526 if (1 != sscanf(position + 1, "%d", &port_unused)) {
529 /* Store it in *port. */
530 strncpy(port, position + 1, 5);
532 /* And remove port from host. */