1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 * 21 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 22 * Use is subject to license terms. 23 */ 24 25 #pragma ident "%Z%%M% %I% %E% SMI" 26 27 /* 28 * A SOCKS client that let's users 'ssh' to the 29 * outside of the firewall by opening up a connection 30 * through the SOCKS server. Supports only SOCKS v5. 31 */ 32 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 #include <netdb.h> 37 #include <strings.h> 38 #include <unistd.h> 39 #include <inttypes.h> 40 #include <errno.h> 41 #include <poll.h> 42 #include <signal.h> 43 #include <locale.h> 44 #include <libintl.h> 45 #include <netinet/in.h> 46 #include <sys/types.h> 47 #include <sys/socket.h> 48 #include <arpa/inet.h> 49 #include <sys/time.h> 50 #include <sys/stropts.h> 51 #include <sys/stat.h> 52 #include <sys/varargs.h> 53 #include "proxy-io.h" 54 55 #define DEFAULT_SOCKS5_PORT "1080" 56 57 static int debug_flag = 0; 58 59 static void 60 usage(void) 61 { 62 (void) fprintf(stderr, gettext("Usage: ssh-socks5-proxy-connect " 63 "[-h socks5_proxy_host] [-p socks5_proxy_port] \n" 64 "remote_host remote_port\n")); 65 exit(1); 66 } 67 68 /* PRINTFLIKE1 */ 69 static void 70 debug(const char *format, ...) 71 { 72 char fmtbuf[BUFFER_SIZ]; 73 va_list args; 74 75 if (debug_flag == 0) { 76 return; 77 } 78 va_start(args, format); 79 (void) snprintf(fmtbuf, sizeof (fmtbuf), 80 "ssh-socks5-proxy: %s\n", format); 81 (void) vfprintf(stderr, fmtbuf, args); 82 va_end(args); 83 } 84 85 static void 86 signal_handler(int sig) 87 { 88 exit(0); 89 } 90 91 static int 92 do_version_exchange(int sockfd) 93 { 94 char buffer[3], recv_buf[2]; 95 96 buffer[0] = 0x05; /* VER */ 97 buffer[1] = 0x01; /* NMETHODS */ 98 buffer[2] = 0x00; /* METHODS */ 99 100 if (write(sockfd, &buffer, sizeof (buffer)) < 0) { 101 perror("write"); 102 return (0); 103 } 104 105 if (read(sockfd, &recv_buf, sizeof (recv_buf)) == -1) { 106 perror("read"); 107 return (0); 108 } 109 110 /* 111 * No need to check the server's version as per 112 * the protocol spec. Check the method supported 113 * by the server. Currently if the server does not 114 * support NO AUTH, we disconnect. 115 */ 116 if (recv_buf[1] != 0x00) { 117 debug("Unsupported Authentication Method"); 118 return (0); 119 } 120 121 /* Return success. */ 122 return (1); 123 } 124 125 static void 126 send_request( 127 int sockfd, 128 const char *ssh_host, 129 uchar_t ssh_host_len, 130 uint16_t *ssh_port) 131 { 132 int failure = 1; 133 char *buffer, *temp, recv_buf[BUFFER_SIZ]; 134 uchar_t version = 0x05, cmd = 0x01, rsv = 0x00, atyp = 0x03; 135 136 buffer = malloc(strlen(ssh_host) + 7); 137 138 temp = buffer; 139 140 /* Assemble the request packet */ 141 (void) memcpy(temp, &version, sizeof (version)); 142 temp += sizeof (version); 143 (void) memcpy(temp, &cmd, sizeof (cmd)); 144 temp += sizeof (cmd); 145 (void) memcpy(temp, &rsv, sizeof (rsv)); 146 temp += sizeof (rsv); 147 (void) memcpy(temp, &atyp, sizeof (atyp)); 148 temp += sizeof (atyp); 149 (void) memcpy(temp, &ssh_host_len, sizeof (ssh_host_len)); 150 temp += sizeof (ssh_host_len); 151 (void) memcpy(temp, ssh_host, strlen(ssh_host)); 152 temp += strlen(ssh_host); 153 (void) memcpy(temp, ssh_port, sizeof (*ssh_port)); 154 temp += sizeof (*ssh_port); 155 156 if (write(sockfd, buffer, temp - buffer) == -1) { 157 perror("write"); 158 exit(1); 159 } 160 161 /* 162 * The maximum size of the protocol message we are waiting for is 10 163 * bytes -- VER[1], REP[1], RSV[1], ATYP[1], BND.ADDR[4] and 164 * BND.PORT[2]; see RFC 1928, section "6. Replies" for more details. 165 * Everything else is already a part of the data we are supposed to 166 * deliver to the requester. We know that BND.ADDR is exactly 4 bytes 167 * since as you can see below, we accept only ATYP == 1 which specifies 168 * that the IPv4 address is in a binary format. 169 */ 170 if (read(sockfd, &recv_buf, 10) == -1) { 171 perror("read"); 172 exit(1); 173 } 174 175 /* temp now points to the recieve buffer. */ 176 temp = recv_buf; 177 178 /* Check the server's version. */ 179 if (*temp++ != 0x05) { 180 (void) fprintf(stderr, gettext("Unsupported SOCKS version: %x\n"), 181 recv_buf[0]); 182 exit(1); 183 } 184 185 /* Check server's reply */ 186 switch (*temp++) { 187 case 0x00: 188 failure = 0; 189 debug("CONNECT command Succeeded."); 190 break; 191 case 0x01: 192 debug("General SOCKS server failure."); 193 break; 194 case 0x02: 195 debug("Connection not allowed by ruleset."); 196 break; 197 case 0x03: 198 debug("Network Unreachable."); 199 break; 200 case 0x04: 201 debug("Host unreachable."); 202 break; 203 case 0x05: 204 debug("Connection refused."); 205 break; 206 case 0x06: 207 debug("TTL expired."); 208 break; 209 case 0x07: 210 debug("Command not supported"); 211 break; 212 case 0x08: 213 debug("Address type not supported."); 214 break; 215 default: 216 (void) fprintf(stderr, gettext("ssh-socks5-proxy: " 217 "SOCKS Server reply not understood\n")); 218 } 219 220 if (failure == 1) { 221 exit(1); 222 } 223 224 /* Parse the rest of the packet */ 225 226 /* Ignore RSV */ 227 temp++; 228 229 /* Check ATYP */ 230 if (*temp != 0x01) { 231 (void) fprintf(stderr, gettext("ssh-socks5-proxy: " 232 "Address type not supported: %u\n"), *temp); 233 exit(1); 234 } 235 236 free(buffer); 237 } 238 239 int 240 main(int argc, char **argv) 241 { 242 extern char *optarg; 243 extern int optind; 244 int retval, err_code, sock; 245 uint16_t ssh_port; 246 uchar_t ssh_host_len; 247 char *socks_server = NULL, *socks_port = NULL; 248 char *ssh_host; 249 struct addrinfo hints, *ai; 250 struct pollfd fds[2]; 251 252 /* Initialization for variables, set locale and textdomain */ 253 254 (void) setlocale(LC_ALL, ""); 255 256 #if !defined(TEXT_DOMAIN) /* Should be defined by cc -D */ 257 #define TEXT_DOMAIN "SYS_TEST" /* Use this only if it weren't */ 258 #endif 259 (void) textdomain(TEXT_DOMAIN); 260 261 /* Set up the signal handler */ 262 (void) signal(SIGINT, signal_handler); 263 (void) signal(SIGPIPE, signal_handler); 264 (void) signal(SIGPOLL, signal_handler); 265 266 while ((retval = getopt(argc, argv, "dp:h:")) != -1) { 267 switch (retval) { 268 case 'h': 269 socks_server = optarg; 270 break; 271 case 'p': 272 socks_port = optarg; 273 break; 274 case 'd': 275 debug_flag = 1; 276 break; 277 default: 278 break; 279 } 280 } 281 282 if (optind != argc - 2) { 283 usage(); 284 } 285 286 ssh_host = argv[optind++]; 287 ssh_host_len = (uchar_t)strlen(ssh_host); 288 ssh_port = htons(atoi(argv[optind])); 289 290 /* 291 * If the name and/or port number of the 292 * socks server were not passed on the 293 * command line, try the user's environment. 294 */ 295 if (socks_server == NULL) { 296 if ((socks_server = getenv("SOCKS5_SERVER")) == NULL) { 297 (void) fprintf(stderr, gettext("ssh-socks5-proxy: " 298 "SOCKS5 SERVER not specified\n")); 299 exit(1); 300 } 301 } 302 if (socks_port == NULL) { 303 if ((socks_port = getenv("SOCKS5_PORT")) == NULL) { 304 socks_port = DEFAULT_SOCKS5_PORT; 305 } 306 } 307 308 debug("SOCKS5_SERVER = %s", socks_server); 309 debug("SOCKS5_PORT = %s", socks_port); 310 311 bzero(&hints, sizeof (struct addrinfo)); 312 hints.ai_family = PF_UNSPEC; 313 hints.ai_socktype = SOCK_STREAM; 314 315 if ((err_code = getaddrinfo(socks_server, socks_port, &hints, &ai)) 316 != 0) { 317 (void) fprintf(stderr, "%s: %s\n", socks_server, 318 gai_strerror(err_code)); 319 exit(1); 320 } 321 322 if ((sock = socket(ai->ai_family, SOCK_STREAM, 0)) < 0) { 323 perror("socket"); 324 exit(1); 325 } 326 327 /* Connect to the SOCKS server */ 328 if (connect(sock, ai->ai_addr, ai->ai_addrlen) == 0) { 329 debug("Connected to the SOCKS server"); 330 /* Do the SOCKS v5 communication with the server. */ 331 if (do_version_exchange(sock) > 0) { 332 debug("Done version exchange"); 333 send_request(sock, ssh_host, ssh_host_len, &ssh_port); 334 } else { 335 (void) fprintf(stderr, gettext("ssh-socks5-proxy: Client and " 336 "Server versions differ.\n")); 337 (void) close(sock); 338 exit(1); 339 } 340 } else { 341 perror("connect"); 342 (void) close(sock); 343 exit(1); 344 } 345 346 fds[0].fd = STDIN_FILENO; /* Poll stdin for data. */ 347 fds[1].fd = sock; /* Poll the socket for data. */ 348 fds[0].events = fds[1].events = POLLIN; 349 350 for (;;) { 351 if (poll(fds, 2, INFTIM) == -1) { 352 perror("poll"); 353 (void) close(sock); 354 exit(1); 355 } 356 357 /* Data arrived on stdin, write it to the socket */ 358 if (fds[0].revents & POLLIN) { 359 if (proxy_read_write_loop(STDIN_FILENO, sock) == 0) { 360 (void) close(sock); 361 exit(1); 362 } 363 } else if (fds[0].revents & (POLLERR | POLLHUP | POLLNVAL)) { 364 (void) close(sock); 365 exit(1); 366 } 367 368 /* Data arrived on the socket, write it to stdout */ 369 if (fds[1].revents & POLLIN) { 370 if (proxy_read_write_loop(sock, STDOUT_FILENO) == 0) { 371 (void) close(sock); 372 exit(1); 373 } 374 } else if (fds[1].revents & (POLLERR | POLLHUP | POLLNVAL)) { 375 (void) close(sock); 376 exit(1); 377 } 378 } 379 380 /* NOTREACHED */ 381 return (0); 382 } 383