1 /*	$OpenBSD: socks.c,v 1.17 2006/09/25 04:51:20 ray Exp $	*/
2 
3 /*
4  * Copyright (c) 1999 Niklas Hallqvist.  All rights reserved.
5  * Copyright (c) 2004, 2005 Damien Miller.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #pragma ident	"%Z%%M%	%I%	%E% SMI"
29 
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <netinet/in.h>
33 #include <arpa/inet.h>
34 
35 #include <err.h>
36 #include <errno.h>
37 #include <netdb.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42 #include <resolv.h>
43 #include <strings.h>
44 #include "atomicio.h"
45 
46 #define	SOCKS_PORT	"1080"
47 #define	HTTP_PROXY_PORT	"3128"
48 #define	HTTP_MAXHDRS	64
49 #define	SOCKS_V5	5
50 #define	SOCKS_V4	4
51 #define	SOCKS_NOAUTH	0
52 #define	SOCKS_NOMETHOD	0xff
53 #define	SOCKS_CONNECT	1
54 #define	SOCKS_IPV4	1
55 #define	SOCKS_DOMAIN	3
56 #define	SOCKS_IPV6	4
57 
58 #define	HTTP_10_407	"HTTP/1.0 407 "
59 #define	HTTP_10_200	"HTTP/1.0 200 "
60 #define	HTTP_11_200	"HTTP/1.1 200 "
61 
62 int remote_connect(const char *, const char *, struct addrinfo);
63 int socks_connect(const char *, const char *,
64 	    const char *, const char *, struct addrinfo, int,
65 	    const char *);
66 
67 /*
68  * Convert string representation of host (h) and service/port (p) into
69  * sockaddr structure and return 0 on success, -1 on failure.
70  * Indicate whether the host address is IPv4 (v4only) and numeric.
71  */
72 static int
decode_addrport(const char * h,const char * p,struct sockaddr * addr,socklen_t addrlen,int v4only,int numeric)73 decode_addrport(const char *h, const char *p, struct sockaddr *addr,
74     socklen_t addrlen, int v4only, int numeric)
75 {
76 	int r;
77 	struct addrinfo hints, *res;
78 
79 	bzero(&hints, sizeof (hints));
80 	hints.ai_family = v4only ? PF_INET : PF_UNSPEC;
81 	hints.ai_flags = numeric ? AI_NUMERICHOST : 0;
82 	hints.ai_socktype = SOCK_STREAM;
83 	r = getaddrinfo(h, p, &hints, &res);
84 	/* Don't fatal when attempting to convert a numeric address */
85 	if (r != 0) {
86 		if (!numeric) {
87 			errx(1, "getaddrinfo(\"%.64s\", \"%.64s\"): %s", h, p,
88 			    gai_strerror(r));
89 		}
90 		return (-1);
91 	}
92 	if (addrlen < res->ai_addrlen) {
93 		freeaddrinfo(res);
94 		errx(1, "internal error: addrlen < res->ai_addrlen");
95 	}
96 	(void) memcpy(addr, res->ai_addr, res->ai_addrlen);
97 	freeaddrinfo(res);
98 	return (0);
99 }
100 
101 /*
102  * Read single line from a descriptor into buffer up to bufsz bytes,
103  * byte by byte. Returns length of the line (including ending NULL),
104  * exits upon failure.
105  */
106 static int
proxy_read_line(int fd,char * buf,size_t bufsz)107 proxy_read_line(int fd, char *buf, size_t bufsz)
108 {
109 	size_t off;
110 
111 	for (off = 0; ; ) {
112 		if (off >= bufsz)
113 			errx(1, "proxy read too long");
114 		if (atomicio(read, fd, buf + off, 1) != 1)
115 			err(1, "proxy read");
116 		/* Skip CR */
117 		if (buf[off] == '\r')
118 			continue;
119 		if (buf[off] == '\n') {
120 			buf[off] = '\0';
121 			break;
122 		}
123 		/*
124 		 * we rewite \r\n to NULL since socks_connect() relies
125 		 * on *buf being zero in that case.
126 		 */
127 		off++;
128 	}
129 	return (off);
130 }
131 
132 /*
133  * Read proxy password from user and return it. The arguments are used
134  * only for prompt construction.
135  */
136 static const char *
getproxypass(const char * proxyuser,const char * proxyhost)137 getproxypass(const char *proxyuser, const char *proxyhost)
138 {
139 	char prompt[512];
140 	const char *pw;
141 
142 	(void) snprintf(prompt, sizeof (prompt), "Proxy password for %s@%s: ",
143 	    proxyuser, proxyhost);
144 	if ((pw = getpassphrase(prompt)) == NULL)
145 		errx(1, "Unable to read proxy passphrase");
146 	return (pw);
147 }
148 
149 /* perform connection via proxy using SOCKSv[45] or HTTP proxy CONNECT */
150 int
socks_connect(const char * host,const char * port,const char * proxyhost,const char * proxyport,struct addrinfo proxyhints,int socksv,const char * proxyuser)151 socks_connect(const char *host, const char *port, const char *proxyhost,
152     const char *proxyport, struct addrinfo proxyhints, int socksv,
153     const char *proxyuser)
154 {
155 	int proxyfd, r, authretry = 0;
156 	size_t hlen, wlen;
157 	char buf[1024];
158 	size_t cnt;
159 	struct sockaddr_storage addr;
160 	struct sockaddr_in *in4 = (struct sockaddr_in *)&addr;
161 	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&addr;
162 	in_port_t serverport;
163 	const char *proxypass = NULL;
164 
165 	if (proxyport == NULL)
166 		proxyport = (socksv == -1) ? HTTP_PROXY_PORT : SOCKS_PORT;
167 
168 	/* Abuse API to lookup port */
169 	if (decode_addrport("0.0.0.0", port, (struct sockaddr *)&addr,
170 	    sizeof (addr), 1, 1) == -1)
171 		errx(1, "unknown port \"%.64s\"", port);
172 	serverport = in4->sin_port;
173 
174 again:
175 	if (authretry++ > 3)
176 		errx(1, "Too many authentication failures");
177 
178 	proxyfd = remote_connect(proxyhost, proxyport, proxyhints);
179 
180 	if (proxyfd < 0)
181 		return (-1);
182 
183 	if (socksv == 5) {
184 		if (decode_addrport(host, port, (struct sockaddr *)&addr,
185 		    sizeof (addr), 0, 1) == -1)
186 			addr.ss_family = 0; /* used in switch below */
187 
188 		/* Version 5, one method: no authentication */
189 		buf[0] = SOCKS_V5;
190 		buf[1] = 1;
191 		buf[2] = SOCKS_NOAUTH;
192 		cnt = atomicio(vwrite, proxyfd, buf, 3);
193 		if (cnt != 3)
194 			err(1, "write failed (%d/3)", cnt);
195 
196 		cnt = atomicio(read, proxyfd, buf, 2);
197 		if (cnt != 2)
198 			err(1, "read failed (%d/3)", cnt);
199 
200 		if ((unsigned char)buf[1] == SOCKS_NOMETHOD)
201 			errx(1, "authentication method negotiation failed");
202 
203 		switch (addr.ss_family) {
204 		case 0:
205 			/* Version 5, connect: domain name */
206 
207 			/* Max domain name length is 255 bytes */
208 			hlen = strlen(host);
209 			if (hlen > 255)
210 				errx(1, "host name too long for SOCKS5");
211 			buf[0] = SOCKS_V5;
212 			buf[1] = SOCKS_CONNECT;
213 			buf[2] = 0;
214 			buf[3] = SOCKS_DOMAIN;
215 			buf[4] = hlen;
216 			(void) memcpy(buf + 5, host, hlen);
217 			(void) memcpy(buf + 5 + hlen, &serverport,
218 			    sizeof (serverport));
219 			wlen = 5 + hlen + sizeof (serverport);
220 			break;
221 		case AF_INET:
222 			/* Version 5, connect: IPv4 address */
223 			buf[0] = SOCKS_V5;
224 			buf[1] = SOCKS_CONNECT;
225 			buf[2] = 0;
226 			buf[3] = SOCKS_IPV4;
227 			(void) memcpy(buf + 4, &in4->sin_addr,
228 			    sizeof (in4->sin_addr));
229 			(void) memcpy(buf + 8, &in4->sin_port,
230 			    sizeof (in4->sin_port));
231 			wlen = 4 + sizeof (in4->sin_addr) +
232 			    sizeof (in4->sin_port);
233 			break;
234 		case AF_INET6:
235 			/* Version 5, connect: IPv6 address */
236 			buf[0] = SOCKS_V5;
237 			buf[1] = SOCKS_CONNECT;
238 			buf[2] = 0;
239 			buf[3] = SOCKS_IPV6;
240 			(void) memcpy(buf + 4, &in6->sin6_addr,
241 			    sizeof (in6->sin6_addr));
242 			(void) memcpy(buf + 20, &in6->sin6_port,
243 			    sizeof (in6->sin6_port));
244 			wlen = 4 + sizeof (in6->sin6_addr) +
245 			    sizeof (in6->sin6_port);
246 			break;
247 		default:
248 			errx(1, "internal error: silly AF");
249 		}
250 
251 		cnt = atomicio(vwrite, proxyfd, buf, wlen);
252 		if (cnt != wlen)
253 			err(1, "write failed (%d/%d)", cnt, wlen);
254 
255 		/*
256 		 * read proxy reply which is 4 byte "header", BND.ADDR
257 		 * and BND.PORT according to RFC 1928, section 6. BND.ADDR
258 		 * is 4 bytes in case of IPv4 which gives us 10 bytes in sum.
259 		 */
260 		cnt = atomicio(read, proxyfd, buf, 10);
261 		if (cnt != 10)
262 			err(1, "read failed (%d/10)", cnt);
263 		if (buf[1] != 0)
264 			errx(1, "connection failed, SOCKS error %d", buf[1]);
265 	} else if (socksv == 4) {
266 		/* This will exit on lookup failure */
267 		(void) decode_addrport(host, port, (struct sockaddr *)&addr,
268 		    sizeof (addr), 1, 0);
269 
270 		/* Version 4 */
271 		buf[0] = SOCKS_V4;
272 		buf[1] = SOCKS_CONNECT;	/* connect */
273 		(void) memcpy(buf + 2, &in4->sin_port, sizeof (in4->sin_port));
274 		(void) memcpy(buf + 4, &in4->sin_addr, sizeof (in4->sin_addr));
275 		buf[8] = 0;	/* empty username */
276 		wlen = 9;
277 
278 		cnt = atomicio(vwrite, proxyfd, buf, wlen);
279 		if (cnt != wlen)
280 			err(1, "write failed (%d/%d)", cnt, wlen);
281 
282 		/*
283 		 * SOCKSv4 proxy replies consists of 2 byte "header",
284 		 * port number and numeric IPv4 address which gives 8 bytes.
285 		 */
286 		cnt = atomicio(read, proxyfd, buf, 8);
287 		if (cnt != 8)
288 			err(1, "read failed (%d/8)", cnt);
289 		if (buf[1] != 90)
290 			errx(1, "connection failed, SOCKS error %d", buf[1]);
291 	} else if (socksv == -1) {
292 		/* HTTP proxy CONNECT according to RFC 2817, section 5 */
293 
294 		/* Disallow bad chars in hostname */
295 		if (strcspn(host, "\r\n\t []:") != strlen(host))
296 			errx(1, "Invalid hostname");
297 
298 		/* Try to be sane about numeric IPv6 addresses */
299 		if (strchr(host, ':') != NULL) {
300 			r = snprintf(buf, sizeof (buf),
301 			    "CONNECT [%s]:%d HTTP/1.0\r\n",
302 			    host, ntohs(serverport));
303 		} else {
304 			r = snprintf(buf, sizeof (buf),
305 			    "CONNECT %s:%d HTTP/1.0\r\n",
306 			    host, ntohs(serverport));
307 		}
308 		if (r == -1 || (size_t)r >= sizeof (buf))
309 			errx(1, "hostname too long");
310 		r = strlen(buf);
311 
312 		cnt = atomicio(vwrite, proxyfd, buf, r);
313 		if (cnt != r)
314 			err(1, "write failed (%d/%d)", cnt, r);
315 
316 		if (authretry > 1) {
317 			char resp[1024];
318 
319 			proxypass = getproxypass(proxyuser, proxyhost);
320 			r = snprintf(buf, sizeof (buf), "%s:%s",
321 			    proxyuser, proxypass);
322 			free((void *)proxypass);
323 			if (r == -1 || (size_t)r >= sizeof (buf) ||
324 			    b64_ntop((unsigned char *)buf, strlen(buf), resp,
325 			    sizeof (resp)) == -1)
326 				errx(1, "Proxy username/password too long");
327 			r = snprintf(buf, sizeof (buf), "Proxy-Authorization: "
328 			    "Basic %s\r\n", resp);
329 			if (r == -1 || (size_t)r >= sizeof (buf))
330 				errx(1, "Proxy auth response too long");
331 			r = strlen(buf);
332 			if ((cnt = atomicio(vwrite, proxyfd, buf, r)) != r)
333 				err(1, "write failed (%d/%d)", cnt, r);
334 		}
335 
336 		/* Terminate headers */
337 		if ((r = atomicio(vwrite, proxyfd, "\r\n", 2)) != 2)
338 			err(1, "write failed (2/%d)", r);
339 
340 		/* Read status reply */
341 		(void) proxy_read_line(proxyfd, buf, sizeof (buf));
342 		if (proxyuser != NULL &&
343 		    strncmp(buf, HTTP_10_407, strlen(HTTP_10_407)) == 0) {
344 			if (authretry > 1) {
345 				(void) fprintf(stderr, "Proxy authentication "
346 				    "failed\n");
347 			}
348 			(void) close(proxyfd);
349 			goto again;
350 		} else if (strncmp(buf, HTTP_10_200,
351 		    strlen(HTTP_10_200)) != 0 && strncmp(buf, HTTP_11_200,
352 		    strlen(HTTP_11_200)) != 0)
353 			errx(1, "Proxy error: \"%s\"", buf);
354 
355 		/* Headers continue until we hit an empty line */
356 		for (r = 0; r < HTTP_MAXHDRS; r++) {
357 			(void) proxy_read_line(proxyfd, buf, sizeof (buf));
358 			if (*buf == '\0')
359 				break;
360 		}
361 		if (*buf != '\0')
362 			errx(1, "Too many proxy headers received");
363 	} else
364 		errx(1, "Unknown proxy protocol %d", socksv);
365 
366 	return (proxyfd);
367 }
368