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 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 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 * 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 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 (%d/3)", cnt); 193 194 cnt = atomicio(read, proxyfd, buf, 2); 195 if (cnt != 2) 196 err(1, "read failed (%d/3)", 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 (%d/%d)", 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 (%d/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 (%d/%d)", 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 (%d/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 (%d/%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 (%d/%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