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 <fcntl.h> 64 #include <netdb.h> 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <string.h> 68 #include <syslog.h> 69 #include <sys/signal.h> 70 #include <sys/socket.h> 71 #include <sys/ioctl.h> 72 #include <netinet/in.h> 73 #include <netinet/in_systm.h> 74 #include <netinet/ip.h> 75 #include <net/if.h> 76 #include <arpa/inet.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 __P((void)); 88 89 int Set_address(char *addr, struct sockaddr_in *sin) 90 { 91 struct hostent *hp; 92 93 bzero((char *)sin, sizeof(struct sockaddr)); 94 sin->sin_family = AF_INET; 95 if((sin->sin_addr.s_addr = inet_addr(addr)) == (u_long)-1) { 96 hp = gethostbyname(addr); 97 if (!hp) { 98 syslog(LOG_ERR,"unknown host %s", addr); 99 return 1; 100 } 101 sin->sin_family = hp->h_addrtype; 102 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length); 103 } 104 return 0; 105 } 106 107 int tun_open(char *devname, struct sockaddr *ouraddr, char *theiraddr) 108 { 109 int s; 110 struct sockaddr_in *sin; 111 112 /* Open tun device */ 113 tun = open (devname, O_RDWR); 114 if (tun < 0) { 115 syslog(LOG_ERR,"can't open %s - %m",devname); 116 return(1); 117 } 118 119 /* 120 * At first, name the interface. 121 */ 122 bzero((char *)&ifra, sizeof(ifra)); 123 bzero((char *)&ifrq, sizeof(ifrq)); 124 125 strncpy(ifrq.ifr_name, devname+5, IFNAMSIZ); 126 strncpy(ifra.ifra_name, devname+5, IFNAMSIZ); 127 128 s = socket(AF_INET, SOCK_DGRAM, 0); 129 if (s < 0) { 130 syslog(LOG_ERR,"can't open socket - %m"); 131 goto tunc_return; 132 } 133 134 /* 135 * Delete (previous) adresses for interface 136 * 137 * !!!! 138 * On FreeBSD this ioctl returns error 139 * when tunN have no addresses, so - log and ignore it. 140 * 141 */ 142 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 143 syslog(LOG_ERR,"SIOCDIFADDR - %m"); 144 } 145 146 /* 147 * Set interface address 148 */ 149 sin = (struct sockaddr_in *)&(ifra.ifra_addr); 150 bcopy(ouraddr, sin, sizeof(struct sockaddr_in)); 151 sin->sin_len = sizeof(*sin); 152 153 /* 154 * Set destination address 155 */ 156 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 157 if(Set_address(theiraddr,sin)) { 158 syslog(LOG_ERR,"bad destination address: %s",theiraddr); 159 goto stunc_return; 160 } 161 sin->sin_len = sizeof(*sin); 162 163 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 164 syslog(LOG_ERR,"can't set interface address - %m"); 165 goto stunc_return; 166 } 167 168 /* 169 * Now, bring up the interface. 170 */ 171 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 172 syslog(LOG_ERR,"can't get interface flags - %m"); 173 goto stunc_return; 174 } 175 176 ifrq.ifr_flags |= IFF_UP; 177 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 178 close(s); 179 return(0); 180 } 181 syslog(LOG_ERR,"can't set interface UP - %m"); 182 stunc_return: 183 close(s); 184 tunc_return: 185 close(tun); 186 return(1); 187 } 188 189 void Finish(int signum) 190 { 191 int s; 192 193 syslog(LOG_INFO,"exiting"); 194 195 close(net); 196 197 s = socket(AF_INET, SOCK_DGRAM, 0); 198 if (s < 0) { 199 syslog(LOG_ERR,"can't open socket - %m"); 200 goto closing_tun; 201 } 202 203 /* 204 * Shut down interface. 205 */ 206 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 207 syslog(LOG_ERR,"can't get interface flags - %m"); 208 goto closing_fds; 209 } 210 211 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 212 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 213 syslog(LOG_ERR,"can't set interface DOWN - %m"); 214 goto closing_fds; 215 } 216 217 /* 218 * Delete adresses for interface 219 */ 220 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 221 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 222 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 223 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 224 syslog(LOG_ERR,"can't delete interface's addresses - %m"); 225 } 226 closing_fds: 227 close(s); 228 closing_tun: 229 close(tun); 230 closelog(); 231 exit(signum); 232 } 233 234 int main (int argc, char **argv) 235 { 236 int c, len, ipoff; 237 238 char *devname = NULL; 239 char *point_to = NULL; 240 char *to_point = NULL; 241 char *target; 242 char *protocol = NULL; 243 int protnum; 244 245 struct sockaddr t_laddr; /* Source address of tunnel */ 246 struct sockaddr whereto; /* Destination of tunnel */ 247 struct sockaddr_in *to; 248 249 char buf[0x2000]; /* Packets buffer */ 250 struct ip *ip = (struct ip *)buf; 251 252 fd_set rfds, wfds, efds; /* File descriptors for select() */ 253 int nfds; /* Return from select() */ 254 255 256 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) { 257 switch (c) { 258 case 'd': 259 to_point = optarg; 260 break; 261 case 's': 262 point_to = optarg; 263 break; 264 case 't': 265 devname = optarg; 266 break; 267 case 'p': 268 protocol = optarg; 269 break; 270 } 271 } 272 argc -= optind; 273 argv += optind; 274 275 if (argc != 1 || (devname == NULL) || 276 (point_to == NULL) || (to_point == NULL)) { 277 usage(); 278 } 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(devname, &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 (void)signal(SIGHUP,Finish); 320 (void)signal(SIGINT,Finish); 321 (void)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() 366 { 367 fprintf(stderr, 368 "usage: nos-tun -t <tun_name> -s <source_addr> -d <dest_addr> -p <protocol_number> <target_addr>\n"); 369 exit(1); 370 } 371 372