xref: /titanic_41/usr/src/cmd/ssh/ssh-socks5-proxy-connect/ssh-socks5-proxy-connect.c (revision 743541abe0006f1be576e21a976c36fb2e87accc)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  *
21  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
22  * Use is subject to license terms.
23  */
24 
25 #pragma ident	"%Z%%M%	%I%	%E% SMI"
26 
27 /*
28  * A SOCKS client that let's users 'ssh' to the
29  * outside of the firewall by opening up a connection
30  * through the SOCKS server. Supports only SOCKS v5.
31  */
32 
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <netdb.h>
37 #include <strings.h>
38 #include <unistd.h>
39 #include <inttypes.h>
40 #include <errno.h>
41 #include <poll.h>
42 #include <signal.h>
43 #include <locale.h>
44 #include <libintl.h>
45 #include <netinet/in.h>
46 #include <sys/types.h>
47 #include <sys/socket.h>
48 #include <arpa/inet.h>
49 #include <sys/time.h>
50 #include <sys/stropts.h>
51 #include <sys/stat.h>
52 #include <sys/varargs.h>
53 #include "proxy-io.h"
54 
55 #define	DEFAULT_SOCKS5_PORT	"1080"
56 
57 static int debug_flag = 0;
58 
59 static void
usage(void)60 usage(void)
61 {
62 	(void) fprintf(stderr, gettext("Usage: ssh-socks5-proxy-connect "
63 	    "[-h socks5_proxy_host] [-p socks5_proxy_port] \n"
64 	    "remote_host remote_port\n"));
65 	exit(1);
66 }
67 
68 /* PRINTFLIKE1 */
69 static void
debug(const char * format,...)70 debug(const char *format, ...)
71 {
72 	char fmtbuf[BUFFER_SIZ];
73 	va_list args;
74 
75 	if (debug_flag == 0) {
76 	    return;
77 	}
78 	va_start(args, format);
79 	(void) snprintf(fmtbuf, sizeof (fmtbuf),
80 	    "ssh-socks5-proxy: %s\n", format);
81 	(void) vfprintf(stderr, fmtbuf, args);
82 	va_end(args);
83 }
84 
85 static void
signal_handler(int sig)86 signal_handler(int sig)
87 {
88 	exit(0);
89 }
90 
91 static int
do_version_exchange(int sockfd)92 do_version_exchange(int sockfd)
93 {
94 	char buffer[3], recv_buf[2];
95 
96 	buffer[0] = 0x05;			/* VER */
97 	buffer[1] = 0x01;			/* NMETHODS */
98 	buffer[2] = 0x00;			/* METHODS */
99 
100 	if (write(sockfd, &buffer, sizeof (buffer)) < 0) {
101 	    perror("write");
102 	    return (0);
103 	}
104 
105 	if (read(sockfd, &recv_buf, sizeof (recv_buf)) == -1) {
106 	    perror("read");
107 	    return (0);
108 	}
109 
110 	/*
111 	 * No need to check the server's version as per
112 	 * the protocol spec. Check the method supported
113 	 * by the server. Currently if the server does not
114 	 * support NO AUTH, we disconnect.
115 	 */
116 	if (recv_buf[1] != 0x00) {
117 	    debug("Unsupported Authentication Method");
118 	    return (0);
119 	}
120 
121 	/* Return success. */
122 	return (1);
123 }
124 
125 static void
send_request(int sockfd,const char * ssh_host,uchar_t ssh_host_len,uint16_t * ssh_port)126 send_request(
127     int sockfd,
128     const char *ssh_host,
129     uchar_t ssh_host_len,
130     uint16_t *ssh_port)
131 {
132 	int failure = 1;
133 	char *buffer, *temp, recv_buf[BUFFER_SIZ];
134 	uchar_t version = 0x05, cmd = 0x01, rsv = 0x00, atyp = 0x03;
135 
136 	buffer = malloc(strlen(ssh_host) + 7);
137 
138 	temp = buffer;
139 
140 	/* Assemble the request packet */
141 	(void) memcpy(temp, &version, sizeof (version));
142 	temp += sizeof (version);
143 	(void) memcpy(temp, &cmd, sizeof (cmd));
144 	temp += sizeof (cmd);
145 	(void) memcpy(temp, &rsv, sizeof (rsv));
146 	temp += sizeof (rsv);
147 	(void) memcpy(temp, &atyp, sizeof (atyp));
148 	temp += sizeof (atyp);
149 	(void) memcpy(temp, &ssh_host_len, sizeof (ssh_host_len));
150 	temp += sizeof (ssh_host_len);
151 	(void) memcpy(temp, ssh_host, strlen(ssh_host));
152 	temp += strlen(ssh_host);
153 	(void) memcpy(temp, ssh_port, sizeof (*ssh_port));
154 	temp += sizeof (*ssh_port);
155 
156 	if (write(sockfd, buffer, temp - buffer) == -1) {
157 	    perror("write");
158 	    exit(1);
159 	}
160 
161 	/*
162 	 * The maximum size of the protocol message we are waiting for is 10
163 	 * bytes -- VER[1], REP[1], RSV[1], ATYP[1], BND.ADDR[4] and
164 	 * BND.PORT[2]; see RFC 1928, section "6. Replies" for more details.
165 	 * Everything else is already a part of the data we are supposed to
166 	 * deliver to the requester. We know that BND.ADDR is exactly 4 bytes
167 	 * since as you can see below, we accept only ATYP == 1 which specifies
168 	 * that the IPv4 address is in a binary format.
169 	 */
170 	if (read(sockfd, &recv_buf, 10) == -1) {
171 	    perror("read");
172 	    exit(1);
173 	}
174 
175 	/* temp now points to the recieve buffer. */
176 	temp = recv_buf;
177 
178 	/* Check the server's version. */
179 	if (*temp++ != 0x05) {
180 	    (void) fprintf(stderr, gettext("Unsupported SOCKS version: %x\n"),
181 		recv_buf[0]);
182 	    exit(1);
183 	}
184 
185 	/* Check server's reply */
186 	switch (*temp++) {
187 	    case 0x00:
188 		failure = 0;
189 		debug("CONNECT command Succeeded.");
190 		break;
191 	    case 0x01:
192 		debug("General SOCKS server failure.");
193 		break;
194 	    case 0x02:
195 		debug("Connection not allowed by ruleset.");
196 		break;
197 	    case 0x03:
198 		debug("Network Unreachable.");
199 		break;
200 	    case 0x04:
201 		debug("Host unreachable.");
202 		break;
203 	    case 0x05:
204 		debug("Connection refused.");
205 		break;
206 	    case 0x06:
207 		debug("TTL expired.");
208 		break;
209 	    case 0x07:
210 		debug("Command not supported");
211 		break;
212 	    case 0x08:
213 		debug("Address type not supported.");
214 		break;
215 	    default:
216 		(void) fprintf(stderr, gettext("ssh-socks5-proxy: "
217 		    "SOCKS Server reply not understood\n"));
218 	}
219 
220 	if (failure == 1) {
221 	    exit(1);
222 	}
223 
224 	/* Parse the rest of the packet */
225 
226 	/* Ignore RSV */
227 	temp++;
228 
229 	/* Check ATYP */
230 	if (*temp != 0x01) {
231 	    (void) fprintf(stderr, gettext("ssh-socks5-proxy: "
232 		"Address type not supported: %u\n"), *temp);
233 	    exit(1);
234 	}
235 
236 	free(buffer);
237 }
238 
239 int
main(int argc,char ** argv)240 main(int argc, char **argv)
241 {
242 	extern char 	*optarg;
243 	extern int	optind;
244 	int 		retval, err_code, sock;
245 	uint16_t 	ssh_port;
246 	uchar_t 	ssh_host_len;
247 	char 		*socks_server = NULL, *socks_port = NULL;
248 	char 		*ssh_host;
249 	struct 		addrinfo hints, *ai;
250 	struct 		pollfd fds[2];
251 
252 	/* Initialization for variables, set locale and textdomain */
253 
254 	(void) setlocale(LC_ALL, "");
255 
256 #if !defined(TEXT_DOMAIN)	/* Should be defined by cc -D */
257 #define	TEXT_DOMAIN "SYS_TEST"  /* Use this only if it weren't */
258 #endif
259 	(void) textdomain(TEXT_DOMAIN);
260 
261 	/* Set up the signal handler */
262 	(void) signal(SIGINT, signal_handler);
263 	(void) signal(SIGPIPE, signal_handler);
264 	(void) signal(SIGPOLL, signal_handler);
265 
266 	while ((retval = getopt(argc, argv, "dp:h:")) != -1) {
267 	    switch (retval) {
268 		case 'h':
269 		    socks_server = optarg;
270 		    break;
271 		case 'p':
272 		    socks_port = optarg;
273 		    break;
274 		case 'd':
275 		    debug_flag = 1;
276 		    break;
277 		default:
278 		    break;
279 	    }
280 	}
281 
282 	if (optind != argc - 2) {
283 		usage();
284 	}
285 
286 	ssh_host = argv[optind++];
287 	ssh_host_len = (uchar_t)strlen(ssh_host);
288 	ssh_port = htons(atoi(argv[optind]));
289 
290 	/*
291 	 * If the name and/or port number of the
292 	 * socks server were not passed on the
293 	 * command line, try the user's environment.
294 	 */
295 	if (socks_server == NULL) {
296 	    if ((socks_server = getenv("SOCKS5_SERVER")) == NULL) {
297 		(void) fprintf(stderr, gettext("ssh-socks5-proxy: "
298 		    "SOCKS5 SERVER not specified\n"));
299 		exit(1);
300 	    }
301 	}
302 	if (socks_port == NULL) {
303 	    if ((socks_port = getenv("SOCKS5_PORT")) == NULL) {
304 		socks_port = DEFAULT_SOCKS5_PORT;
305 	    }
306 	}
307 
308 	debug("SOCKS5_SERVER = %s", socks_server);
309 	debug("SOCKS5_PORT = %s", socks_port);
310 
311 	bzero(&hints, sizeof (struct addrinfo));
312 	hints.ai_family = PF_UNSPEC;
313 	hints.ai_socktype = SOCK_STREAM;
314 
315 	if ((err_code = getaddrinfo(socks_server, socks_port, &hints, &ai))
316 	    != 0) {
317 	    (void) fprintf(stderr, "%s: %s\n", socks_server,
318 		gai_strerror(err_code));
319 	    exit(1);
320 	}
321 
322 	if ((sock = socket(ai->ai_family, SOCK_STREAM, 0)) < 0) {
323 	    perror("socket");
324 	    exit(1);
325 	}
326 
327 	/* Connect to the SOCKS server */
328 	if (connect(sock, ai->ai_addr, ai->ai_addrlen) == 0) {
329 	    debug("Connected to the SOCKS server");
330 	    /* Do the SOCKS v5 communication with the server. */
331 	    if (do_version_exchange(sock) > 0) {
332 		debug("Done version exchange");
333 		send_request(sock, ssh_host, ssh_host_len, &ssh_port);
334 	    } else {
335 		(void) fprintf(stderr, gettext("ssh-socks5-proxy: Client and "
336 		    "Server versions differ.\n"));
337 		(void) close(sock);
338 		exit(1);
339 	    }
340 	} else {
341 	    perror("connect");
342 	    (void) close(sock);
343 	    exit(1);
344 	}
345 
346 	fds[0].fd = STDIN_FILENO; 	/* Poll stdin for data. */
347 	fds[1].fd = sock; 		/* Poll the socket for data. */
348 	fds[0].events = fds[1].events = POLLIN;
349 
350 	for (;;) {
351 	    if (poll(fds, 2, INFTIM) == -1) {
352 		perror("poll");
353 		(void) close(sock);
354 		exit(1);
355 	    }
356 
357 	    /* Data arrived on stdin, write it to the socket */
358 	    if (fds[0].revents & POLLIN) {
359 		if (proxy_read_write_loop(STDIN_FILENO, sock) == 0) {
360 			(void) close(sock);
361 			exit(1);
362 		}
363 	    } else if (fds[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
364 		(void) close(sock);
365 		exit(1);
366 	    }
367 
368 	    /* Data arrived on the socket, write it to stdout */
369 	    if (fds[1].revents & POLLIN) {
370 		if (proxy_read_write_loop(sock, STDOUT_FILENO) == 0) {
371 			(void) close(sock);
372 			exit(1);
373 		}
374 	    } else if (fds[1].revents & (POLLERR | POLLHUP | POLLNVAL)) {
375 		(void) close(sock);
376 		exit(1);
377 	    }
378 	}
379 
380 	/* NOTREACHED */
381 	return (0);
382 }
383