1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 1996, Nickolay Dudorov 5 * 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 unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 */ 30 31 /* 32 * 'nos-tun' program configure tunN interface as a point-to-point 33 * connection with two "pseudo"-addresses between this host and 34 * 'target'. 35 * 36 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP) 37 * (known as NOS-incapsulation in CISCO-routers' terminology). 38 * 39 * 'nos-tun' can works with itself and CISCO-routers. 40 * (It may also work with Linux 'nos-tun's, but 41 * I have no Linux system here to test with). 42 * 43 * BUGS (or features ?): 44 * - you must specify ONE of the target host's addresses 45 * ( nos-tun sends and accepts packets only to/from this 46 * address ) 47 * - there can be only ONE tunnel between two hosts, 48 * more precisely - between given host and (one of) 49 * target hosts' address(es) 50 * (and why do you want more ?) 51 */ 52 53 /* 54 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com> 55 * I added a new flag for ip protocol number. 56 * We are using 4 as protocol number in ampr.org. 57 * 58 */ 59 60 #include <sys/types.h> 61 #include <sys/ioctl.h> 62 #include <sys/signal.h> 63 #include <sys/socket.h> 64 65 #include <net/if.h> 66 #include <netinet/in.h> 67 #include <netinet/in_systm.h> 68 #include <netinet/ip.h> 69 70 #include <arpa/inet.h> 71 #include <fcntl.h> 72 #include <netdb.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <syslog.h> 77 #include <unistd.h> 78 79 /* Tunnel interface configuration stuff */ 80 static struct ifaliasreq ifra; 81 static struct ifreq ifrq; 82 83 /* Global descriptors */ 84 int net; /* socket descriptor */ 85 int tun; /* tunnel descriptor */ 86 87 static void usage(void) __dead2; 88 89 static int 90 Set_address(char *addr, struct sockaddr_in *sin) 91 { 92 struct hostent *hp; 93 94 bzero((char *)sin, sizeof(struct sockaddr)); 95 sin->sin_family = AF_INET; 96 if((sin->sin_addr.s_addr = inet_addr(addr)) == INADDR_NONE) { 97 hp = gethostbyname(addr); 98 if (!hp) { 99 syslog(LOG_ERR,"unknown host %s", addr); 100 return 1; 101 } 102 sin->sin_family = hp->h_addrtype; 103 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length); 104 } 105 return 0; 106 } 107 108 static int 109 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr) 110 { 111 int s; 112 struct sockaddr_in *sin; 113 114 /* Open tun device */ 115 tun = open(dev_name, O_RDWR); 116 if (tun < 0) { 117 syslog(LOG_ERR,"can't open %s - %m", dev_name); 118 return(1); 119 } 120 121 /* 122 * At first, name the interface. 123 */ 124 bzero((char *)&ifra, sizeof(ifra)); 125 bzero((char *)&ifrq, sizeof(ifrq)); 126 127 strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ); 128 strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ); 129 130 s = socket(AF_INET, SOCK_DGRAM, 0); 131 if (s < 0) { 132 syslog(LOG_ERR,"can't open socket - %m"); 133 goto tunc_return; 134 } 135 136 /* 137 * Delete (previous) addresses for interface 138 * 139 * !!!! 140 * On FreeBSD this ioctl returns error 141 * when tunN have no addresses, so - log and ignore it. 142 * 143 */ 144 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 145 syslog(LOG_ERR,"SIOCDIFADDR - %m"); 146 } 147 148 /* 149 * Set interface address 150 */ 151 sin = (struct sockaddr_in *)&(ifra.ifra_addr); 152 bcopy(ouraddr, sin, sizeof(struct sockaddr_in)); 153 sin->sin_len = sizeof(*sin); 154 155 /* 156 * Set destination address 157 */ 158 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 159 if(Set_address(theiraddr,sin)) { 160 syslog(LOG_ERR,"bad destination address: %s",theiraddr); 161 goto stunc_return; 162 } 163 sin->sin_len = sizeof(*sin); 164 165 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 166 syslog(LOG_ERR,"can't set interface address - %m"); 167 goto stunc_return; 168 } 169 170 /* 171 * Now, bring up the interface. 172 */ 173 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 174 syslog(LOG_ERR,"can't get interface flags - %m"); 175 goto stunc_return; 176 } 177 178 ifrq.ifr_flags |= IFF_UP; 179 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 180 close(s); 181 return(0); 182 } 183 syslog(LOG_ERR,"can't set interface UP - %m"); 184 stunc_return: 185 close(s); 186 tunc_return: 187 close(tun); 188 return(1); 189 } 190 191 static void 192 Finish(int signum) 193 { 194 int s; 195 196 syslog(LOG_INFO,"exiting"); 197 198 close(net); 199 200 s = socket(AF_INET, SOCK_DGRAM, 0); 201 if (s < 0) { 202 syslog(LOG_ERR,"can't open socket - %m"); 203 goto closing_tun; 204 } 205 206 /* 207 * Shut down interface. 208 */ 209 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 210 syslog(LOG_ERR,"can't get interface flags - %m"); 211 goto closing_fds; 212 } 213 214 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 215 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 216 syslog(LOG_ERR,"can't set interface DOWN - %m"); 217 goto closing_fds; 218 } 219 220 /* 221 * Delete addresses for interface 222 */ 223 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 224 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 225 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 226 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 227 syslog(LOG_ERR,"can't delete interface's addresses - %m"); 228 } 229 closing_fds: 230 close(s); 231 closing_tun: 232 close(tun); 233 closelog(); 234 exit(signum); 235 } 236 237 int main (int argc, char **argv) 238 { 239 int c, len, ipoff; 240 241 char *dev_name = NULL; 242 char *point_to = NULL; 243 char *to_point = NULL; 244 char *target; 245 char *source = NULL; 246 char *protocol = NULL; 247 int protnum; 248 249 struct sockaddr t_laddr; /* Source address of tunnel */ 250 struct sockaddr whereto; /* Destination of tunnel */ 251 struct sockaddr wherefrom; /* Source of tunnel */ 252 struct sockaddr_in *to; 253 254 char buf[0x2000]; /* Packets buffer */ 255 struct ip *ip = (struct ip *)buf; 256 257 fd_set rfds; /* File descriptors for select() */ 258 int nfds; /* Return from select() */ 259 int lastfd; /* highest fd we care about */ 260 261 262 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) { 263 switch (c) { 264 case 'd': 265 to_point = optarg; 266 break; 267 case 's': 268 point_to = optarg; 269 break; 270 case 't': 271 dev_name = optarg; 272 break; 273 case 'p': 274 protocol = optarg; 275 break; 276 } 277 } 278 argc -= optind; 279 argv += optind; 280 281 if ((argc != 1 && argc != 2) || (dev_name == NULL) || 282 (point_to == NULL) || (to_point == NULL)) { 283 usage(); 284 } 285 286 if(protocol == NULL) 287 protnum = 94; 288 else 289 protnum = atoi(protocol); 290 291 if (argc == 1) { 292 target = *argv; 293 } else { 294 source = *argv++; target = *argv; 295 } 296 297 /* Establish logging through 'syslog' */ 298 openlog("nos-tun", LOG_PID, LOG_DAEMON); 299 300 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) { 301 closelog(); 302 exit(2); 303 } 304 305 if(tun_open(dev_name, &t_laddr, to_point)) { 306 closelog(); 307 exit(3); 308 } 309 310 to = (struct sockaddr_in *)&whereto; 311 if(Set_address(target, to)) 312 Finish(4); 313 314 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) { 315 syslog(LOG_ERR,"can't open socket - %m"); 316 Finish(5); 317 } 318 319 if (source) { 320 if (Set_address(source, (struct sockaddr_in *)&wherefrom)) 321 Finish(9); 322 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) { 323 syslog(LOG_ERR, "can't bind source address - %m"); 324 Finish(10); 325 } 326 } 327 328 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) { 329 syslog(LOG_ERR,"can't connect to target - %m"); 330 close(net); 331 Finish(6); 332 } 333 334 /* Demonize it */ 335 daemon(0,0); 336 337 /* Install signal handlers */ 338 (void)signal(SIGHUP,Finish); 339 (void)signal(SIGINT,Finish); 340 (void)signal(SIGTERM,Finish); 341 342 if (tun > net) 343 lastfd = tun; 344 else 345 lastfd = net; 346 347 for (;;) { 348 /* Set file descriptors for select() */ 349 FD_ZERO(&rfds); 350 FD_SET(tun,&rfds); FD_SET(net,&rfds); 351 352 nfds = select(lastfd+1,&rfds,NULL,NULL,NULL); 353 if(nfds < 0) { 354 syslog(LOG_ERR,"interrupted select"); 355 close(net); 356 Finish(7); 357 } 358 if(nfds == 0) { /* Impossible ? */ 359 syslog(LOG_ERR,"timeout in select"); 360 close(net); 361 Finish(8); 362 } 363 364 365 if(FD_ISSET(net,&rfds)) { 366 /* Read from socket ... */ 367 len = read(net, buf, sizeof(buf)); 368 /* Check if this is "our" packet */ 369 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) { 370 /* ... skip encapsulation headers ... */ 371 ipoff = (ip->ip_hl << 2); 372 /* ... and write to tun-device */ 373 write(tun,buf+ipoff,len-ipoff); 374 } 375 } 376 377 if(FD_ISSET(tun,&rfds)) { 378 /* Read from tun ... */ 379 len = read(tun, buf, sizeof(buf)); 380 /* ... and send to network */ 381 if(send(net, buf, len,0) <= 0) { 382 syslog(LOG_ERR,"can't send - %m"); 383 } 384 } 385 } 386 } 387 388 static void 389 usage(void) 390 { 391 fprintf(stderr, 392 "usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n"); 393 exit(1); 394 } 395 396