nos-tun.c revision 141611 
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
59static const char rcsid[] =
60  "$FreeBSD: head/sbin/nos-tun/nos-tun.c 141611 2005-02-10 09:19:34Z ru $";
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 */
83static struct ifaliasreq ifra;
84static struct ifreq ifrq;
85
86/* Global descriptors */
87int net;                          /* socket descriptor */
88int tun;                          /* tunnel descriptor */
89
90static void usage(void);
91
92int Set_address(char *addr, struct sockaddr_in *sin)
93{
94  struct hostent *hp;
95
96  bzero((char *)sin, sizeof(struct sockaddr));
97  sin->sin_family = AF_INET;
98  if((sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) {
99    hp = gethostbyname(addr);
100    if (!hp) {
101      syslog(LOG_ERR,"unknown host %s", addr);
102      return 1;
103    }
104    sin->sin_family = hp->h_addrtype;
105    bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
106  }
107  return 0;
108}
109
110int tun_open(char *devname, struct sockaddr *ouraddr, char *theiraddr)
111{
112  int s;
113  struct sockaddr_in *sin;
114
115  /* Open tun device */
116  tun = open (devname, O_RDWR);
117  if (tun < 0) {
118    syslog(LOG_ERR,"can't open %s - %m",devname);
119    return(1);
120  }
121
122  /*
123   * At first, name the interface.
124   */
125  bzero((char *)&ifra, sizeof(ifra));
126  bzero((char *)&ifrq, sizeof(ifrq));
127
128  strncpy(ifrq.ifr_name, devname+5, IFNAMSIZ);
129  strncpy(ifra.ifra_name, devname+5, IFNAMSIZ);
130
131  s = socket(AF_INET, SOCK_DGRAM, 0);
132  if (s < 0) {
133    syslog(LOG_ERR,"can't open socket - %m");
134    goto tunc_return;
135  }
136
137  /*
138   *  Delete (previous) addresses for interface
139   *
140   *  !!!!
141   *  On FreeBSD this ioctl returns error
142   *  when tunN have no addresses, so - log and ignore it.
143   *
144   */
145  if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
146    syslog(LOG_ERR,"SIOCDIFADDR - %m");
147  }
148
149  /*
150   *  Set interface address
151   */
152  sin = (struct sockaddr_in *)&(ifra.ifra_addr);
153  bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
154  sin->sin_len = sizeof(*sin);
155
156  /*
157   *  Set destination address
158   */
159  sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
160  if(Set_address(theiraddr,sin)) {
161    syslog(LOG_ERR,"bad destination address: %s",theiraddr);
162    goto stunc_return;
163  }
164  sin->sin_len = sizeof(*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");
185stunc_return:
186  close(s);
187tunc_return:
188  close(tun);
189  return(1);
190}
191
192void 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  }
229closing_fds:
230  close(s);
231closing_tun:
232  close(tun);
233  closelog();
234  exit(signum);
235}
236
237int main (int argc, char **argv)
238{
239  int  c, len, ipoff;
240
241  char *devname = 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      devname = 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) || (devname == 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(devname, &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
388static void
389usage()
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