sbin/nos-tun/nos-tun.c

   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  * $DragonFly: src/sbin/nos-tun/nos-tun.c,v 1.6 2005/04/18 20:17:58 joerg Exp $
  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 <fcntl.h>
  61 #include <netdb.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <syslog.h>
  66 #include <sys/signal.h>
  67 #include <sys/socket.h>
  68 #include <sys/ioctl.h>
  69 #include <netinet/in.h>
  70 #include <netinet/in_systm.h>
  71 #include <netinet/ip.h>
  72 #include <net/if.h>
  73 #include <arpa/inet.h>
  74 #include <unistd.h>
  75
  76 /* Tunnel interface configuration stuff */
  77 static struct ifaliasreq ifra;
  78 static struct ifreq ifrq;
  79
  80 /* Global descriptors */
  81 int net;                          /* socket descriptor */
  82 int tun;                          /* tunnel descriptor */
  83
  84 static void usage(void);
  85
  86 static int
  87 Set_address(char *addr, struct sockaddr_in *my_sin)
  88 {
  89   struct hostent *hp;
  90
  91   bzero(my_sin, sizeof(struct sockaddr));
  92   my_sin->sin_family = AF_INET;
  93   if((my_sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) {
  94     hp = gethostbyname(addr);
  95     if (!hp) {
  96       syslog(LOG_ERR,"unknown host %s", addr);
  97       return 1;
  98     }
  99     my_sin->sin_family = hp->h_addrtype;
 100     bcopy(hp->h_addr, (caddr_t)&my_sin->sin_addr, hp->h_length);
 101   }
 102   return 0;
 103 }
 104
 105 static int
 106 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr)
 107 {
 108   int s;
 109   struct sockaddr_in *my_sin;
 110
 111   /* Open tun device */
 112   tun = open (dev_name, O_RDWR);
 113   if (tun < 0) {
 114     syslog(LOG_ERR,"can't open %s - %m",dev_name);
 115     return(1);
 116   }
 117
 118   /*
 119    * At first, name the interface.
 120    */
 121   bzero((char *)&ifra, sizeof(ifra));
 122   bzero((char *)&ifrq, sizeof(ifrq));
 123
 124   strncpy(ifrq.ifr_name, dev_name + 5, IFNAMSIZ);
 125   strncpy(ifra.ifra_name, dev_name + 5, IFNAMSIZ);
 126
 127   s = socket(AF_INET, SOCK_DGRAM, 0);
 128   if (s < 0) {
 129     syslog(LOG_ERR,"can't open socket - %m");
 130     goto tunc_return;
 131   }
 132
 133   /*
 134    *  Delete (previous) addresses for interface
 135    *
 136    *  !!!!
 137    *  On FreeBSD this ioctl returns error
 138    *  when tunN have no addresses, so - log and ignore it.
 139    *
 140    */
 141   if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
 142     syslog(LOG_ERR,"SIOCDIFADDR - %m");
 143   }
 144
 145   /*
 146    *  Set interface address
 147    */
 148   my_sin = (struct sockaddr_in *)&(ifra.ifra_addr);
 149   bcopy(ouraddr, my_sin, sizeof(struct sockaddr_in));
 150   my_sin->sin_len = sizeof(*my_sin);
 151
 152   /*
 153    *  Set destination address
 154    */
 155   my_sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
 156   if (Set_address(theiraddr, my_sin)) {
 157     syslog(LOG_ERR,"bad destination address: %s",theiraddr);
 158     goto stunc_return;
 159   }
 160   my_sin->sin_len = sizeof(*my_sin);
 161
 162   if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
 163     syslog(LOG_ERR,"can't set interface address - %m");
 164     goto stunc_return;
 165   }
 166
 167   /*
 168    *  Now, bring up the interface.
 169    */
 170   if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
 171     syslog(LOG_ERR,"can't get interface flags - %m");
 172     goto stunc_return;
 173   }
 174
 175   ifrq.ifr_flags |= IFF_UP;
 176   if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
 177     close(s);
 178     return(0);
 179   }
 180   syslog(LOG_ERR,"can't set interface UP - %m");
 181 stunc_return:
 182   close(s);
 183 tunc_return:
 184   close(tun);
 185   return(1);
 186 }
 187
 188 static void
 189 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 addresses 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 *dev_name = 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       dev_name = optarg;
 266       break;
 267     case 'p':
 268       protocol = optarg;
 269       break;
 270     }
 271   }
 272   argc -= optind;
 273   argv += optind;
 274
 275   if (argc != 1 || (dev_name == 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(dev_name, &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,
 368 "usage: nos-tun -t <tun_name> -s <source_addr> -d <dest_addr> -p <protocol_number> <target_addr>\n");
 369         exit(1);
 370 }
 371