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 * $FreeBSD: src/sbin/nos-tun/nos-tun.c,v 1.6.2.2 2001/08/01 23:14:00 obrien Exp $ 28 */ 29 30 /* 31 * 'nos-tun' program configure tunN interface as a point-to-point 32 * connection with two "pseudo"-addresses between this host and 33 * 'target'. 34 * 35 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP) 36 * (known as NOS-incapsulation in CISCO-routers' terminology). 37 * 38 * 'nos-tun' can works with itself and CISCO-routers. 39 * (It may also work with Linux 'nos-tun's, but 40 * I have no Linux system here to test with). 41 * 42 * BUGS (or features ?): 43 * - you must specify ONE of the target host's addresses 44 * ( nos-tun sends and accepts packets only to/from this 45 * address ) 46 * - there can be only ONE tunnel between two hosts, 47 * more precisely - between given host and (one of) 48 * target hosts' address(es) 49 * (and why do you want more ?) 50 */ 51 52 /* 53 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com> 54 * I added a new flag for ip protocol number. 55 * We are using 4 as protocol number in ampr.org. 56 */ 57 58 #include <fcntl.h> 59 #include <netdb.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <syslog.h> 64 #include <sys/signal.h> 65 #include <sys/socket.h> 66 #include <sys/ioctl.h> 67 #include <netinet/in.h> 68 #include <netinet/in_systm.h> 69 #include <netinet/ip.h> 70 #include <net/if.h> 71 #include <net/tun/if_tun.h> 72 #include <arpa/inet.h> 73 #include <unistd.h> 74 75 /* Tunnel interface configuration stuff */ 76 static struct ifaliasreq ifra; 77 static struct ifreq ifrq; 78 79 /* Tun(4) device autocloner */ 80 static const char *tun_dev = "/dev/tun"; 81 82 /* Global descriptors */ 83 int net; /* socket descriptor */ 84 int tun; /* tunnel descriptor */ 85 86 static void usage(void); 87 88 static int 89 Set_address(char *addr, struct sockaddr_in *my_sin) 90 { 91 struct hostent *hp; 92 93 bzero(my_sin, sizeof(struct sockaddr)); 94 my_sin->sin_family = AF_INET; 95 if((my_sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) { 96 hp = gethostbyname(addr); 97 if (!hp) { 98 syslog(LOG_ERR,"unknown host %s", addr); 99 return 1; 100 } 101 my_sin->sin_family = hp->h_addrtype; 102 bcopy(hp->h_addr, (caddr_t)&my_sin->sin_addr, hp->h_length); 103 } 104 return 0; 105 } 106 107 static int 108 tun_open(struct sockaddr *ouraddr, char *theiraddr) 109 { 110 int s; 111 struct sockaddr_in *my_sin; 112 113 /* Open tun device */ 114 tun = open(tun_dev, O_RDWR); 115 if (tun < 0) { 116 syslog(LOG_ERR,"can't open %s - %m",tun_dev); 117 return(1); 118 } 119 120 /* 121 * At first, name the interface. 122 */ 123 bzero((char *)&ifra, sizeof(ifra)); 124 bzero((char *)&ifrq, sizeof(ifrq)); 125 126 if (ioctl(tun, TUNGIFNAME, &ifrq) < 0) { 127 syslog(LOG_ERR,"can't get tun interface name - %m"); 128 goto tunc_return; 129 } 130 strlcpy(ifra.ifra_name, ifrq.ifr_name, IFNAMSIZ); 131 132 s = socket(AF_INET, SOCK_DGRAM, 0); 133 if (s < 0) { 134 syslog(LOG_ERR,"can't open socket - %m"); 135 goto tunc_return; 136 } 137 138 /* 139 * Delete (previous) addresses for interface 140 * 141 * !!!! 142 * On FreeBSD this ioctl returns error 143 * when tunN have no addresses, so - log and ignore it. 144 */ 145 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 146 syslog(LOG_ERR,"SIOCDIFADDR - %m"); 147 } 148 149 /* 150 * Set interface address 151 */ 152 my_sin = (struct sockaddr_in *)&(ifra.ifra_addr); 153 bcopy(ouraddr, my_sin, sizeof(struct sockaddr_in)); 154 my_sin->sin_len = sizeof(*my_sin); 155 156 /* 157 * Set destination address 158 */ 159 my_sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 160 if (Set_address(theiraddr, my_sin)) { 161 syslog(LOG_ERR,"bad destination address: %s",theiraddr); 162 goto stunc_return; 163 } 164 my_sin->sin_len = sizeof(*my_sin); 165 166 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 167 syslog(LOG_ERR,"can't set interface address - %m"); 168 goto stunc_return; 169 } 170 171 /* 172 * Now, bring up the interface. 173 */ 174 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 175 syslog(LOG_ERR,"can't get interface flags - %m"); 176 goto stunc_return; 177 } 178 179 ifrq.ifr_flags |= IFF_UP; 180 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 181 close(s); 182 return(0); 183 } 184 syslog(LOG_ERR,"can't set interface UP - %m"); 185 186 stunc_return: 187 close(s); 188 tunc_return: 189 close(tun); 190 return(1); 191 } 192 193 static void 194 Finish(int signum) 195 { 196 int s; 197 198 syslog(LOG_INFO,"exiting"); 199 200 close(net); 201 202 s = socket(AF_INET, SOCK_DGRAM, 0); 203 if (s < 0) { 204 syslog(LOG_ERR,"can't open socket - %m"); 205 goto closing_tun; 206 } 207 208 /* 209 * Shut down interface. 210 */ 211 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 212 syslog(LOG_ERR,"can't get interface flags - %m"); 213 goto closing_fds; 214 } 215 216 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 217 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 218 syslog(LOG_ERR,"can't set interface DOWN - %m"); 219 goto closing_fds; 220 } 221 222 /* 223 * Delete addresses for interface 224 */ 225 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 226 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 227 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 228 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 229 syslog(LOG_ERR,"can't delete interface's addresses - %m"); 230 } 231 232 closing_fds: 233 close(s); 234 closing_tun: 235 close(tun); 236 closelog(); 237 exit(signum); 238 } 239 240 int 241 main(int argc, char **argv) 242 { 243 int c, len, ipoff; 244 245 char *point_to = NULL; 246 char *to_point = NULL; 247 char *target; 248 char *protocol = NULL; 249 int protnum; 250 251 struct sockaddr t_laddr; /* Source address of tunnel */ 252 struct sockaddr whereto; /* Destination of tunnel */ 253 struct sockaddr_in *to; 254 255 char buf[0x2000]; /* Packets buffer */ 256 struct ip *ip = (struct ip *)buf; 257 258 fd_set rfds, wfds, efds; /* File descriptors for select() */ 259 int nfds; /* Return from select() */ 260 261 while ((c = getopt(argc, argv, "d:s:p:")) != -1) { 262 switch (c) { 263 case 'd': 264 to_point = optarg; 265 break; 266 case 's': 267 point_to = optarg; 268 break; 269 case 'p': 270 protocol = optarg; 271 break; 272 } 273 } 274 argc -= optind; 275 argv += optind; 276 277 if (argc != 1 || (point_to == NULL) || (to_point == NULL)) 278 usage(); 279 280 if(protocol == NULL) 281 protnum = 94; 282 else 283 protnum = atoi(protocol); 284 285 target = *argv; 286 287 /* Establish logging through 'syslog' */ 288 openlog("nos-tun", LOG_PID, LOG_DAEMON); 289 290 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) { 291 closelog(); 292 exit(2); 293 } 294 295 if(tun_open(&t_laddr, to_point)) { 296 closelog(); 297 exit(3); 298 } 299 300 to = (struct sockaddr_in *)&whereto; 301 if(Set_address(target, to)) 302 Finish(4); 303 304 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) { 305 syslog(LOG_ERR,"can't open socket - %m"); 306 Finish(5); 307 } 308 309 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) { 310 syslog(LOG_ERR,"can't connect to target - %m"); 311 close(net); 312 Finish(6); 313 } 314 315 /* Demonize it */ 316 daemon(0,0); 317 318 /* Install signal handlers */ 319 signal(SIGHUP,Finish); 320 signal(SIGINT,Finish); 321 signal(SIGTERM,Finish); 322 323 for (;;) { 324 /* Set file descriptors for select() */ 325 FD_ZERO(&rfds); FD_ZERO(&wfds); FD_ZERO(&efds); 326 FD_SET(tun,&rfds); FD_SET(net,&rfds); 327 328 nfds = select(net+10,&rfds,&wfds,&efds,NULL); 329 if(nfds < 0) { 330 syslog(LOG_ERR,"interrupted select"); 331 close(net); 332 Finish(7); 333 } 334 if(nfds == 0) { /* Impossible ? */ 335 syslog(LOG_ERR,"timeout in select"); 336 close(net); 337 Finish(8); 338 } 339 340 341 if(FD_ISSET(net,&rfds)) { 342 /* Read from socket ... */ 343 len = read(net, buf, sizeof(buf)); 344 /* Check if this is "our" packet */ 345 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) { 346 /* ... skip encapsulation headers ... */ 347 ipoff = (ip->ip_hl << 2); 348 /* ... and write to tun-device */ 349 write(tun,buf+ipoff,len-ipoff); 350 } 351 } 352 353 if(FD_ISSET(tun,&rfds)) { 354 /* Read from tun ... */ 355 len = read(tun, buf, sizeof(buf)); 356 /* ... and send to network */ 357 if(send(net, buf, len,0) <= 0) { 358 syslog(LOG_ERR,"can't send - %m"); 359 } 360 } 361 } 362 } 363 364 static void 365 usage(void) 366 { 367 fprintf(stderr, "usage: nos-tun -s <source_addr> -d <dest_addr> " 368 "-p <protocol_number> <target_addr>\n"); 369 exit(1); 370 } 371 372