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
62int remote_connect(const char *, const char *, struct addrinfo);
63int 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 */
72static int
73decode_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 */
106static int
107proxy_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 */
136static const char *
137getproxypass(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 */
150int
151socks_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
174again:
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