1 /* 2 * Copyright (c) 1996, Nickolay Dudorov 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 /* 30 * 'nos-tun' program configure tunN interface as a point-to-point 31 * connection with two "pseudo"-addresses between this host and 32 * 'target'. 33 * 34 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP) 35 * (known as NOS-incapsulation in CISCO-routers' terminology). 36 * 37 * 'nos-tun' can works with itself and CISCO-routers. 38 * (It may also work with Linux 'nos-tun's, but 39 * I have no Linux system here to test with). 40 * 41 * BUGS (or features ?): 42 * - you must specify ONE of the target host's addresses 43 * ( nos-tun sends and accepts packets only to/from this 44 * address ) 45 * - there can be only ONE tunnel between two hosts, 46 * more precisely - between given host and (one of) 47 * target hosts' address(es) 48 * (and why do you want more ?) 49 */ 50 51 /* 52 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com> 53 * I added a new flag for ip protocol number. 54 * We are using 4 as protocol number in ampr.org. 55 * 56 */ 57 58 #ifndef lint 59 static const char rcsid[] = 60 "$FreeBSD$"; 61 #endif /* not lint */ 62 63 #include <sys/types.h> 64 #include <sys/ioctl.h> 65 #include <sys/signal.h> 66 #include <sys/socket.h> 67 68 #include <net/if.h> 69 #include <netinet/in.h> 70 #include <netinet/in_systm.h> 71 #include <netinet/ip.h> 72 73 #include <arpa/inet.h> 74 #include <fcntl.h> 75 #include <netdb.h> 76 #include <stdio.h> 77 #include <stdlib.h> 78 #include <string.h> 79 #include <syslog.h> 80 #include <unistd.h> 81 82 /* Tunnel interface configuration stuff */ 83 static struct ifaliasreq ifra; 84 static struct ifreq ifrq; 85 86 /* Global descriptors */ 87 int net; /* socket descriptor */ 88 int tun; /* tunnel descriptor */ 89 90 static void usage(void); 91 92 static int 93 Set_address(char *addr, struct sockaddr_in *sin) 94 { 95 struct hostent *hp; 96 97 bzero((char *)sin, sizeof(struct sockaddr)); 98 sin->sin_family = AF_INET; 99 if((sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) { 100 hp = gethostbyname(addr); 101 if (!hp) { 102 syslog(LOG_ERR,"unknown host %s", addr); 103 return 1; 104 } 105 sin->sin_family = hp->h_addrtype; 106 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length); 107 } 108 return 0; 109 } 110 111 static int 112 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr) 113 { 114 int s; 115 struct sockaddr_in *sin; 116 117 /* Open tun device */ 118 tun = open(dev_name, O_RDWR); 119 if (tun < 0) { 120 syslog(LOG_ERR,"can't open %s - %m", dev_name); 121 return(1); 122 } 123 124 /* 125 * At first, name the interface. 126 */ 127 bzero((char *)&ifra, sizeof(ifra)); 128 bzero((char *)&ifrq, sizeof(ifrq)); 129 130 strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ); 131 strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ); 132 133 s = socket(AF_INET, SOCK_DGRAM, 0); 134 if (s < 0) { 135 syslog(LOG_ERR,"can't open socket - %m"); 136 goto tunc_return; 137 } 138 139 /* 140 * Delete (previous) addresses for interface 141 * 142 * !!!! 143 * On FreeBSD this ioctl returns error 144 * when tunN have no addresses, so - log and ignore it. 145 * 146 */ 147 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 148 syslog(LOG_ERR,"SIOCDIFADDR - %m"); 149 } 150 151 /* 152 * Set interface address 153 */ 154 sin = (struct sockaddr_in *)&(ifra.ifra_addr); 155 bcopy(ouraddr, sin, sizeof(struct sockaddr_in)); 156 sin->sin_len = sizeof(*sin); 157 158 /* 159 * Set destination address 160 */ 161 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 162 if(Set_address(theiraddr,sin)) { 163 syslog(LOG_ERR,"bad destination address: %s",theiraddr); 164 goto stunc_return; 165 } 166 sin->sin_len = sizeof(*sin); 167 168 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 169 syslog(LOG_ERR,"can't set interface address - %m"); 170 goto stunc_return; 171 } 172 173 /* 174 * Now, bring up the interface. 175 */ 176 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 177 syslog(LOG_ERR,"can't get interface flags - %m"); 178 goto stunc_return; 179 } 180 181 ifrq.ifr_flags |= IFF_UP; 182 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 183 close(s); 184 return(0); 185 } 186 syslog(LOG_ERR,"can't set interface UP - %m"); 187 stunc_return: 188 close(s); 189 tunc_return: 190 close(tun); 191 return(1); 192 } 193 194 static void 195 Finish(int signum) 196 { 197 int s; 198 199 syslog(LOG_INFO,"exiting"); 200 201 close(net); 202 203 s = socket(AF_INET, SOCK_DGRAM, 0); 204 if (s < 0) { 205 syslog(LOG_ERR,"can't open socket - %m"); 206 goto closing_tun; 207 } 208 209 /* 210 * Shut down interface. 211 */ 212 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 213 syslog(LOG_ERR,"can't get interface flags - %m"); 214 goto closing_fds; 215 } 216 217 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 218 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 219 syslog(LOG_ERR,"can't set interface DOWN - %m"); 220 goto closing_fds; 221 } 222 223 /* 224 * Delete addresses for interface 225 */ 226 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 227 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 228 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 229 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 230 syslog(LOG_ERR,"can't delete interface's addresses - %m"); 231 } 232 closing_fds: 233 close(s); 234 closing_tun: 235 close(tun); 236 closelog(); 237 exit(signum); 238 } 239 240 int main (int argc, char **argv) 241 { 242 int c, len, ipoff; 243 244 char *dev_name = NULL; 245 char *point_to = NULL; 246 char *to_point = NULL; 247 char *target; 248 char *source = NULL; 249 char *protocol = NULL; 250 int protnum; 251 252 struct sockaddr t_laddr; /* Source address of tunnel */ 253 struct sockaddr whereto; /* Destination of tunnel */ 254 struct sockaddr wherefrom; /* Source of tunnel */ 255 struct sockaddr_in *to; 256 257 char buf[0x2000]; /* Packets buffer */ 258 struct ip *ip = (struct ip *)buf; 259 260 fd_set rfds; /* File descriptors for select() */ 261 int nfds; /* Return from select() */ 262 int lastfd; /* highest fd we care about */ 263 264 265 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) { 266 switch (c) { 267 case 'd': 268 to_point = optarg; 269 break; 270 case 's': 271 point_to = optarg; 272 break; 273 case 't': 274 dev_name = optarg; 275 break; 276 case 'p': 277 protocol = optarg; 278 break; 279 } 280 } 281 argc -= optind; 282 argv += optind; 283 284 if ((argc != 1 && argc != 2) || (dev_name == NULL) || 285 (point_to == NULL) || (to_point == NULL)) { 286 usage(); 287 } 288 289 if(protocol == NULL) 290 protnum = 94; 291 else 292 protnum = atoi(protocol); 293 294 if (argc == 1) { 295 target = *argv; 296 } else { 297 source = *argv++; target = *argv; 298 } 299 300 /* Establish logging through 'syslog' */ 301 openlog("nos-tun", LOG_PID, LOG_DAEMON); 302 303 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) { 304 closelog(); 305 exit(2); 306 } 307 308 if(tun_open(dev_name, &t_laddr, to_point)) { 309 closelog(); 310 exit(3); 311 } 312 313 to = (struct sockaddr_in *)&whereto; 314 if(Set_address(target, to)) 315 Finish(4); 316 317 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) { 318 syslog(LOG_ERR,"can't open socket - %m"); 319 Finish(5); 320 } 321 322 if (source) { 323 if (Set_address(source, (struct sockaddr_in *)&wherefrom)) 324 Finish(9); 325 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) { 326 syslog(LOG_ERR, "can't bind source address - %m"); 327 Finish(10); 328 } 329 } 330 331 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) { 332 syslog(LOG_ERR,"can't connect to target - %m"); 333 close(net); 334 Finish(6); 335 } 336 337 /* Demonize it */ 338 daemon(0,0); 339 340 /* Install signal handlers */ 341 (void)signal(SIGHUP,Finish); 342 (void)signal(SIGINT,Finish); 343 (void)signal(SIGTERM,Finish); 344 345 if (tun > net) 346 lastfd = tun; 347 else 348 lastfd = net; 349 350 for (;;) { 351 /* Set file descriptors for select() */ 352 FD_ZERO(&rfds); 353 FD_SET(tun,&rfds); FD_SET(net,&rfds); 354 355 nfds = select(lastfd+1,&rfds,NULL,NULL,NULL); 356 if(nfds < 0) { 357 syslog(LOG_ERR,"interrupted select"); 358 close(net); 359 Finish(7); 360 } 361 if(nfds == 0) { /* Impossible ? */ 362 syslog(LOG_ERR,"timeout in select"); 363 close(net); 364 Finish(8); 365 } 366 367 368 if(FD_ISSET(net,&rfds)) { 369 /* Read from socket ... */ 370 len = read(net, buf, sizeof(buf)); 371 /* Check if this is "our" packet */ 372 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) { 373 /* ... skip encapsulation headers ... */ 374 ipoff = (ip->ip_hl << 2); 375 /* ... and write to tun-device */ 376 write(tun,buf+ipoff,len-ipoff); 377 } 378 } 379 380 if(FD_ISSET(tun,&rfds)) { 381 /* Read from tun ... */ 382 len = read(tun, buf, sizeof(buf)); 383 /* ... and send to network */ 384 if(send(net, buf, len,0) <= 0) { 385 syslog(LOG_ERR,"can't send - %m"); 386 } 387 } 388 } 389 } 390 391 static void 392 usage(void) 393 { 394 fprintf(stderr, 395 "usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n"); 396 exit(1); 397 } 398 399