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