1 /* $OpenBSD: socks.c,v 1.23 2015/12/10 18:31:52 mmcc 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 <readpassphrase.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 int remote_connect(const char *, const char *, struct addrinfo); 57 int socks_connect(const char *, const char *, struct addrinfo, 58 const char *, const char *, struct addrinfo, int, 59 const char *); 60 61 static int 62 decode_addrport(const char *h, const char *p, struct sockaddr *addr, 63 socklen_t addrlen, int v4only, int numeric) 64 { 65 int r; 66 struct addrinfo hints, *res; 67 68 bzero(&hints, sizeof(hints)); 69 hints.ai_family = v4only ? PF_INET : PF_UNSPEC; 70 hints.ai_flags = numeric ? AI_NUMERICHOST : 0; 71 hints.ai_socktype = SOCK_STREAM; 72 r = getaddrinfo(h, p, &hints, &res); 73 /* Don't fatal when attempting to convert a numeric address */ 74 if (r != 0) { 75 if (!numeric) { 76 errx(1, "getaddrinfo(\"%.64s\", \"%.64s\"): %s", h, p, 77 gai_strerror(r)); 78 } 79 return (-1); 80 } 81 if (addrlen < res->ai_addrlen) { 82 freeaddrinfo(res); 83 errx(1, "internal error: addrlen < res->ai_addrlen"); 84 } 85 memcpy(addr, res->ai_addr, res->ai_addrlen); 86 freeaddrinfo(res); 87 return (0); 88 } 89 90 static int 91 proxy_read_line(int fd, char *buf, size_t bufsz) 92 { 93 size_t off; 94 95 for(off = 0;;) { 96 if (off >= bufsz) 97 errx(1, "proxy read too long"); 98 if (atomicio(read, fd, buf + off, 1) != 1) 99 err(1, "proxy read"); 100 /* Skip CR */ 101 if (buf[off] == '\r') 102 continue; 103 if (buf[off] == '\n') { 104 buf[off] = '\0'; 105 break; 106 } 107 off++; 108 } 109 return (off); 110 } 111 112 static const char * 113 getproxypass(const char *proxyuser, const char *proxyhost) 114 { 115 char prompt[512]; 116 static char pw[256]; 117 118 snprintf(prompt, sizeof(prompt), "Proxy password for %s@%s: ", 119 proxyuser, proxyhost); 120 if (readpassphrase(prompt, pw, sizeof(pw), RPP_REQUIRE_TTY) == NULL) 121 errx(1, "Unable to read proxy passphrase"); 122 return (pw); 123 } 124 125 /* 126 * Error strings adapted from the generally accepted SOCKSv4 spec: 127 * 128 * http://ftp.icm.edu.pl/packages/socks/socks4/SOCKS4.protocol 129 */ 130 static const char * 131 socks4_strerror(int e) 132 { 133 switch (e) { 134 case 90: 135 return "Succeeded"; 136 case 91: 137 return "Request rejected or failed"; 138 case 92: 139 return "SOCKS server cannot connect to identd on the client"; 140 case 93: 141 return "Client program and identd report different user-ids"; 142 default: 143 return "Unknown error"; 144 } 145 } 146 147 /* 148 * Error strings taken almost directly from RFC 1928. 149 */ 150 static const char * 151 socks5_strerror(int e) 152 { 153 switch (e) { 154 case 0: 155 return "Succeeded"; 156 case 1: 157 return "General SOCKS server failure"; 158 case 2: 159 return "Connection not allowed by ruleset"; 160 case 3: 161 return "Network unreachable"; 162 case 4: 163 return "Host unreachable"; 164 case 5: 165 return "Connection refused"; 166 case 6: 167 return "TTL expired"; 168 case 7: 169 return "Command not supported"; 170 case 8: 171 return "Address type not supported"; 172 default: 173 return "Unknown error"; 174 } 175 } 176 177 int 178 socks_connect(const char *host, const char *port, 179 struct addrinfo hints __attribute__ ((__unused__)), 180 const char *proxyhost, const char *proxyport, struct addrinfo proxyhints, 181 int socksv, const char *proxyuser) 182 { 183 int proxyfd, r, authretry = 0; 184 size_t hlen, wlen; 185 unsigned char buf[1024]; 186 size_t cnt; 187 struct sockaddr_storage addr; 188 struct sockaddr_in *in4 = (struct sockaddr_in *)&addr; 189 struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&addr; 190 in_port_t serverport; 191 const char *proxypass = NULL; 192 193 if (proxyport == NULL) 194 proxyport = (socksv == -1) ? HTTP_PROXY_PORT : SOCKS_PORT; 195 196 /* Abuse API to lookup port */ 197 if (decode_addrport("0.0.0.0", port, (struct sockaddr *)&addr, 198 sizeof(addr), 1, 1) == -1) 199 errx(1, "unknown port \"%.64s\"", port); 200 serverport = in4->sin_port; 201 202 again: 203 if (authretry++ > 3) 204 errx(1, "Too many authentication failures"); 205 206 proxyfd = remote_connect(proxyhost, proxyport, proxyhints); 207 208 if (proxyfd < 0) 209 return (-1); 210 211 if (socksv == 5) { 212 if (decode_addrport(host, port, (struct sockaddr *)&addr, 213 sizeof(addr), 0, 1) == -1) 214 addr.ss_family = 0; /* used in switch below */ 215 216 /* Version 5, one method: no authentication */ 217 buf[0] = SOCKS_V5; 218 buf[1] = 1; 219 buf[2] = SOCKS_NOAUTH; 220 cnt = atomicio(vwrite, proxyfd, buf, 3); 221 if (cnt != 3) 222 err(1, "write failed (%zu/3)", cnt); 223 224 cnt = atomicio(read, proxyfd, buf, 2); 225 if (cnt != 2) 226 err(1, "read failed (%zu/3)", cnt); 227 228 if (buf[1] == SOCKS_NOMETHOD) 229 errx(1, "authentication method negotiation failed"); 230 231 switch (addr.ss_family) { 232 case 0: 233 /* Version 5, connect: domain name */ 234 235 /* Max domain name length is 255 bytes */ 236 hlen = strlen(host); 237 if (hlen > 255) 238 errx(1, "host name too long for SOCKS5"); 239 buf[0] = SOCKS_V5; 240 buf[1] = SOCKS_CONNECT; 241 buf[2] = 0; 242 buf[3] = SOCKS_DOMAIN; 243 buf[4] = hlen; 244 memcpy(buf + 5, host, hlen); 245 memcpy(buf + 5 + hlen, &serverport, sizeof serverport); 246 wlen = 7 + hlen; 247 break; 248 case AF_INET: 249 /* Version 5, connect: IPv4 address */ 250 buf[0] = SOCKS_V5; 251 buf[1] = SOCKS_CONNECT; 252 buf[2] = 0; 253 buf[3] = SOCKS_IPV4; 254 memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr); 255 memcpy(buf + 8, &in4->sin_port, sizeof in4->sin_port); 256 wlen = 10; 257 break; 258 case AF_INET6: 259 /* Version 5, connect: IPv6 address */ 260 buf[0] = SOCKS_V5; 261 buf[1] = SOCKS_CONNECT; 262 buf[2] = 0; 263 buf[3] = SOCKS_IPV6; 264 memcpy(buf + 4, &in6->sin6_addr, sizeof in6->sin6_addr); 265 memcpy(buf + 20, &in6->sin6_port, 266 sizeof in6->sin6_port); 267 wlen = 22; 268 break; 269 default: 270 errx(1, "internal error: silly AF"); 271 } 272 273 cnt = atomicio(vwrite, proxyfd, buf, wlen); 274 if (cnt != wlen) 275 err(1, "write failed (%zu/%zu)", cnt, wlen); 276 277 cnt = atomicio(read, proxyfd, buf, 4); 278 if (cnt != 4) 279 err(1, "read failed (%zu/4)", cnt); 280 if (buf[1] != 0) { 281 errx(1, "connection failed, SOCKSv5 error: %s", 282 socks5_strerror(buf[1])); 283 } 284 switch (buf[3]) { 285 case SOCKS_IPV4: 286 cnt = atomicio(read, proxyfd, buf + 4, 6); 287 if (cnt != 6) 288 err(1, "read failed (%zu/6)", cnt); 289 break; 290 case SOCKS_IPV6: 291 cnt = atomicio(read, proxyfd, buf + 4, 18); 292 if (cnt != 18) 293 err(1, "read failed (%zu/18)", cnt); 294 break; 295 default: 296 errx(1, "connection failed, unsupported address type"); 297 } 298 } else if (socksv == 4) { 299 /* This will exit on lookup failure */ 300 decode_addrport(host, port, (struct sockaddr *)&addr, 301 sizeof(addr), 1, 0); 302 303 /* Version 4 */ 304 buf[0] = SOCKS_V4; 305 buf[1] = SOCKS_CONNECT; /* connect */ 306 memcpy(buf + 2, &in4->sin_port, sizeof in4->sin_port); 307 memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr); 308 buf[8] = 0; /* empty username */ 309 wlen = 9; 310 311 cnt = atomicio(vwrite, proxyfd, buf, wlen); 312 if (cnt != wlen) 313 err(1, "write failed (%zu/%zu)", cnt, wlen); 314 315 cnt = atomicio(read, proxyfd, buf, 8); 316 if (cnt != 8) 317 err(1, "read failed (%zu/8)", cnt); 318 if (buf[1] != 90) { 319 errx(1, "connection failed, SOCKSv4 error: %s", 320 socks4_strerror(buf[1])); 321 } 322 } else if (socksv == -1) { 323 /* HTTP proxy CONNECT */ 324 325 /* Disallow bad chars in hostname */ 326 if (strcspn(host, "\r\n\t []:") != strlen(host)) 327 errx(1, "Invalid hostname"); 328 329 /* Try to be sane about numeric IPv6 addresses */ 330 if (strchr(host, ':') != NULL) { 331 r = snprintf(buf, sizeof(buf), 332 "CONNECT [%s]:%d HTTP/1.0\r\n", 333 host, ntohs(serverport)); 334 } else { 335 r = snprintf(buf, sizeof(buf), 336 "CONNECT %s:%d HTTP/1.0\r\n", 337 host, ntohs(serverport)); 338 } 339 if (r == -1 || (size_t)r >= sizeof(buf)) 340 errx(1, "hostname too long"); 341 r = strlen(buf); 342 343 cnt = atomicio(vwrite, proxyfd, buf, r); 344 if (cnt != r) 345 err(1, "write failed (%zu/%d)", cnt, r); 346 347 if (authretry > 1) { 348 char resp[1024]; 349 350 proxypass = getproxypass(proxyuser, proxyhost); 351 r = snprintf(buf, sizeof(buf), "%s:%s", 352 proxyuser, proxypass); 353 if (r == -1 || (size_t)r >= sizeof(buf) || 354 b64_ntop(buf, strlen(buf), resp, 355 sizeof(resp)) == -1) 356 errx(1, "Proxy username/password too long"); 357 r = snprintf(buf, sizeof(buf), "Proxy-Authorization: " 358 "Basic %s\r\n", resp); 359 if (r == -1 || (size_t)r >= sizeof(buf)) 360 errx(1, "Proxy auth response too long"); 361 r = strlen(buf); 362 if ((cnt = atomicio(vwrite, proxyfd, buf, r)) != r) 363 err(1, "write failed (%zu/%d)", cnt, r); 364 } 365 366 /* Terminate headers */ 367 if ((cnt = atomicio(vwrite, proxyfd, "\r\n", 2)) != 2) 368 err(1, "write failed (%zu/2)", cnt); 369 370 /* Read status reply */ 371 proxy_read_line(proxyfd, buf, sizeof(buf)); 372 if (proxyuser != NULL && 373 strncmp(buf, "HTTP/1.0 407 ", 12) == 0) { 374 if (authretry > 1) { 375 fprintf(stderr, "Proxy authentication " 376 "failed\n"); 377 } 378 close(proxyfd); 379 goto again; 380 } else if (strncmp(buf, "HTTP/1.0 200 ", 12) != 0 && 381 strncmp(buf, "HTTP/1.1 200 ", 12) != 0) 382 errx(1, "Proxy error: \"%s\"", buf); 383 384 /* Headers continue until we hit an empty line */ 385 for (r = 0; r < HTTP_MAXHDRS; r++) { 386 proxy_read_line(proxyfd, buf, sizeof(buf)); 387 if (*buf == '\0') 388 break; 389 } 390 if (*buf != '\0') 391 errx(1, "Too many proxy headers received"); 392 } else 393 errx(1, "Unknown proxy protocol %d", socksv); 394 395 return (proxyfd); 396 } 397