1 /* $OpenBSD: socks.c,v 1.21 2015/03/26 21:19:51 tobias 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 int 126 socks_connect(const char *host, const char *port, 127 struct addrinfo hints __attribute__ ((__unused__)), 128 const char *proxyhost, const char *proxyport, struct addrinfo proxyhints, 129 int socksv, const char *proxyuser) 130 { 131 int proxyfd, r, authretry = 0; 132 size_t hlen, wlen; 133 unsigned char buf[1024]; 134 size_t cnt; 135 struct sockaddr_storage addr; 136 struct sockaddr_in *in4 = (struct sockaddr_in *)&addr; 137 struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&addr; 138 in_port_t serverport; 139 const char *proxypass = NULL; 140 141 if (proxyport == NULL) 142 proxyport = (socksv == -1) ? HTTP_PROXY_PORT : SOCKS_PORT; 143 144 /* Abuse API to lookup port */ 145 if (decode_addrport("0.0.0.0", port, (struct sockaddr *)&addr, 146 sizeof(addr), 1, 1) == -1) 147 errx(1, "unknown port \"%.64s\"", port); 148 serverport = in4->sin_port; 149 150 again: 151 if (authretry++ > 3) 152 errx(1, "Too many authentication failures"); 153 154 proxyfd = remote_connect(proxyhost, proxyport, proxyhints); 155 156 if (proxyfd < 0) 157 return (-1); 158 159 if (socksv == 5) { 160 if (decode_addrport(host, port, (struct sockaddr *)&addr, 161 sizeof(addr), 0, 1) == -1) 162 addr.ss_family = 0; /* used in switch below */ 163 164 /* Version 5, one method: no authentication */ 165 buf[0] = SOCKS_V5; 166 buf[1] = 1; 167 buf[2] = SOCKS_NOAUTH; 168 cnt = atomicio(vwrite, proxyfd, buf, 3); 169 if (cnt != 3) 170 err(1, "write failed (%zu/3)", cnt); 171 172 cnt = atomicio(read, proxyfd, buf, 2); 173 if (cnt != 2) 174 err(1, "read failed (%zu/3)", cnt); 175 176 if (buf[1] == SOCKS_NOMETHOD) 177 errx(1, "authentication method negotiation failed"); 178 179 switch (addr.ss_family) { 180 case 0: 181 /* Version 5, connect: domain name */ 182 183 /* Max domain name length is 255 bytes */ 184 hlen = strlen(host); 185 if (hlen > 255) 186 errx(1, "host name too long for SOCKS5"); 187 buf[0] = SOCKS_V5; 188 buf[1] = SOCKS_CONNECT; 189 buf[2] = 0; 190 buf[3] = SOCKS_DOMAIN; 191 buf[4] = hlen; 192 memcpy(buf + 5, host, hlen); 193 memcpy(buf + 5 + hlen, &serverport, sizeof serverport); 194 wlen = 7 + hlen; 195 break; 196 case AF_INET: 197 /* Version 5, connect: IPv4 address */ 198 buf[0] = SOCKS_V5; 199 buf[1] = SOCKS_CONNECT; 200 buf[2] = 0; 201 buf[3] = SOCKS_IPV4; 202 memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr); 203 memcpy(buf + 8, &in4->sin_port, sizeof in4->sin_port); 204 wlen = 10; 205 break; 206 case AF_INET6: 207 /* Version 5, connect: IPv6 address */ 208 buf[0] = SOCKS_V5; 209 buf[1] = SOCKS_CONNECT; 210 buf[2] = 0; 211 buf[3] = SOCKS_IPV6; 212 memcpy(buf + 4, &in6->sin6_addr, sizeof in6->sin6_addr); 213 memcpy(buf + 20, &in6->sin6_port, 214 sizeof in6->sin6_port); 215 wlen = 22; 216 break; 217 default: 218 errx(1, "internal error: silly AF"); 219 } 220 221 cnt = atomicio(vwrite, proxyfd, buf, wlen); 222 if (cnt != wlen) 223 err(1, "write failed (%zu/%zu)", cnt, wlen); 224 225 cnt = atomicio(read, proxyfd, buf, 4); 226 if (cnt != 4) 227 err(1, "read failed (%zu/4)", cnt); 228 if (buf[1] != 0) 229 errx(1, "connection failed, SOCKS error %d", buf[1]); 230 switch (buf[3]) { 231 case SOCKS_IPV4: 232 cnt = atomicio(read, proxyfd, buf + 4, 6); 233 if (cnt != 6) 234 err(1, "read failed (%zu/6)", cnt); 235 break; 236 case SOCKS_IPV6: 237 cnt = atomicio(read, proxyfd, buf + 4, 18); 238 if (cnt != 18) 239 err(1, "read failed (%zu/18)", cnt); 240 break; 241 default: 242 errx(1, "connection failed, unsupported address type"); 243 } 244 } else if (socksv == 4) { 245 /* This will exit on lookup failure */ 246 decode_addrport(host, port, (struct sockaddr *)&addr, 247 sizeof(addr), 1, 0); 248 249 /* Version 4 */ 250 buf[0] = SOCKS_V4; 251 buf[1] = SOCKS_CONNECT; /* connect */ 252 memcpy(buf + 2, &in4->sin_port, sizeof in4->sin_port); 253 memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr); 254 buf[8] = 0; /* empty username */ 255 wlen = 9; 256 257 cnt = atomicio(vwrite, proxyfd, buf, wlen); 258 if (cnt != wlen) 259 err(1, "write failed (%zu/%zu)", cnt, wlen); 260 261 cnt = atomicio(read, proxyfd, buf, 8); 262 if (cnt != 8) 263 err(1, "read failed (%zu/8)", cnt); 264 if (buf[1] != 90) 265 errx(1, "connection failed, SOCKS error %d", buf[1]); 266 } else if (socksv == -1) { 267 /* HTTP proxy CONNECT */ 268 269 /* Disallow bad chars in hostname */ 270 if (strcspn(host, "\r\n\t []:") != strlen(host)) 271 errx(1, "Invalid hostname"); 272 273 /* Try to be sane about numeric IPv6 addresses */ 274 if (strchr(host, ':') != NULL) { 275 r = snprintf(buf, sizeof(buf), 276 "CONNECT [%s]:%d HTTP/1.0\r\n", 277 host, ntohs(serverport)); 278 } else { 279 r = snprintf(buf, sizeof(buf), 280 "CONNECT %s:%d HTTP/1.0\r\n", 281 host, ntohs(serverport)); 282 } 283 if (r == -1 || (size_t)r >= sizeof(buf)) 284 errx(1, "hostname too long"); 285 r = strlen(buf); 286 287 cnt = atomicio(vwrite, proxyfd, buf, r); 288 if (cnt != r) 289 err(1, "write failed (%zu/%d)", cnt, r); 290 291 if (authretry > 1) { 292 char resp[1024]; 293 294 proxypass = getproxypass(proxyuser, proxyhost); 295 r = snprintf(buf, sizeof(buf), "%s:%s", 296 proxyuser, proxypass); 297 if (r == -1 || (size_t)r >= sizeof(buf) || 298 b64_ntop(buf, strlen(buf), resp, 299 sizeof(resp)) == -1) 300 errx(1, "Proxy username/password too long"); 301 r = snprintf(buf, sizeof(buf), "Proxy-Authorization: " 302 "Basic %s\r\n", resp); 303 if (r == -1 || (size_t)r >= sizeof(buf)) 304 errx(1, "Proxy auth response too long"); 305 r = strlen(buf); 306 if ((cnt = atomicio(vwrite, proxyfd, buf, r)) != r) 307 err(1, "write failed (%zu/%d)", cnt, r); 308 } 309 310 /* Terminate headers */ 311 if ((cnt = atomicio(vwrite, proxyfd, "\r\n", 2)) != 2) 312 err(1, "write failed (%zu/2)", cnt); 313 314 /* Read status reply */ 315 proxy_read_line(proxyfd, buf, sizeof(buf)); 316 if (proxyuser != NULL && 317 strncmp(buf, "HTTP/1.0 407 ", 12) == 0) { 318 if (authretry > 1) { 319 fprintf(stderr, "Proxy authentication " 320 "failed\n"); 321 } 322 close(proxyfd); 323 goto again; 324 } else if (strncmp(buf, "HTTP/1.0 200 ", 12) != 0 && 325 strncmp(buf, "HTTP/1.1 200 ", 12) != 0) 326 errx(1, "Proxy error: \"%s\"", buf); 327 328 /* Headers continue until we hit an empty line */ 329 for (r = 0; r < HTTP_MAXHDRS; r++) { 330 proxy_read_line(proxyfd, buf, sizeof(buf)); 331 if (*buf == '\0') 332 break; 333 } 334 if (*buf != '\0') 335 errx(1, "Too many proxy headers received"); 336 } else 337 errx(1, "Unknown proxy protocol %d", socksv); 338 339 return (proxyfd); 340 } 341