1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1996, Nickolay Dudorov
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice unmodified, this list of conditions, and the following
12 *    disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
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#ifndef lint
61static const char rcsid[] =
62  "$FreeBSD$";
63#endif /* not lint */
64
65#include <sys/types.h>
66#include <sys/ioctl.h>
67#include <sys/signal.h>
68#include <sys/socket.h>
69
70#include <net/if.h>
71#include <netinet/in.h>
72#include <netinet/in_systm.h>
73#include <netinet/ip.h>
74
75#include <arpa/inet.h>
76#include <fcntl.h>
77#include <netdb.h>
78#include <stdio.h>
79#include <stdlib.h>
80#include <string.h>
81#include <syslog.h>
82#include <unistd.h>
83
84/* Tunnel interface configuration stuff */
85static struct ifaliasreq ifra;
86static struct ifreq ifrq;
87
88/* Global descriptors */
89int net;                          /* socket descriptor */
90int tun;                          /* tunnel descriptor */
91
92static void usage(void);
93
94static int
95Set_address(char *addr, struct sockaddr_in *sin)
96{
97  struct hostent *hp;
98
99  bzero((char *)sin, sizeof(struct sockaddr));
100  sin->sin_family = AF_INET;
101  if((sin->sin_addr.s_addr = inet_addr(addr)) == INADDR_NONE) {
102    hp = gethostbyname(addr);
103    if (!hp) {
104      syslog(LOG_ERR,"unknown host %s", addr);
105      return 1;
106    }
107    sin->sin_family = hp->h_addrtype;
108    bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
109  }
110  return 0;
111}
112
113static int
114tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr)
115{
116  int s;
117  struct sockaddr_in *sin;
118
119  /* Open tun device */
120  tun = open(dev_name, O_RDWR);
121  if (tun < 0) {
122    syslog(LOG_ERR,"can't open %s - %m", dev_name);
123    return(1);
124  }
125
126  /*
127   * At first, name the interface.
128   */
129  bzero((char *)&ifra, sizeof(ifra));
130  bzero((char *)&ifrq, sizeof(ifrq));
131
132  strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ);
133  strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ);
134
135  s = socket(AF_INET, SOCK_DGRAM, 0);
136  if (s < 0) {
137    syslog(LOG_ERR,"can't open socket - %m");
138    goto tunc_return;
139  }
140
141  /*
142   *  Delete (previous) addresses for interface
143   *
144   *  !!!!
145   *  On FreeBSD this ioctl returns error
146   *  when tunN have no addresses, so - log and ignore it.
147   *
148   */
149  if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
150    syslog(LOG_ERR,"SIOCDIFADDR - %m");
151  }
152
153  /*
154   *  Set interface address
155   */
156  sin = (struct sockaddr_in *)&(ifra.ifra_addr);
157  bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
158  sin->sin_len = sizeof(*sin);
159
160  /*
161   *  Set destination address
162   */
163  sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
164  if(Set_address(theiraddr,sin)) {
165    syslog(LOG_ERR,"bad destination address: %s",theiraddr);
166    goto stunc_return;
167  }
168  sin->sin_len = sizeof(*sin);
169
170  if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
171    syslog(LOG_ERR,"can't set interface address - %m");
172    goto stunc_return;
173  }
174
175  /*
176   *  Now, bring up the interface.
177   */
178  if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
179    syslog(LOG_ERR,"can't get interface flags - %m");
180    goto stunc_return;
181  }
182
183  ifrq.ifr_flags |= IFF_UP;
184  if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
185    close(s);
186    return(0);
187  }
188  syslog(LOG_ERR,"can't set interface UP - %m");
189stunc_return:
190  close(s);
191tunc_return:
192  close(tun);
193  return(1);
194}
195
196static void
197Finish(int signum)
198{
199  int s;
200
201  syslog(LOG_INFO,"exiting");
202
203  close(net);
204
205  s = socket(AF_INET, SOCK_DGRAM, 0);
206  if (s < 0) {
207    syslog(LOG_ERR,"can't open socket - %m");
208    goto closing_tun;
209  }
210
211  /*
212   *  Shut down interface.
213   */
214  if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
215    syslog(LOG_ERR,"can't get interface flags - %m");
216    goto closing_fds;
217  }
218
219  ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
220  if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
221    syslog(LOG_ERR,"can't set interface DOWN - %m");
222    goto closing_fds;
223  }
224
225  /*
226   *  Delete addresses for interface
227   */
228  bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
229  bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
230  bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
231  if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
232    syslog(LOG_ERR,"can't delete interface's addresses - %m");
233  }
234closing_fds:
235  close(s);
236closing_tun:
237  close(tun);
238  closelog();
239  exit(signum);
240}
241
242int main (int argc, char **argv)
243{
244  int  c, len, ipoff;
245
246  char *dev_name = NULL;
247  char *point_to = NULL;
248  char *to_point = NULL;
249  char *target;
250  char *source = NULL;
251  char *protocol = NULL;
252  int protnum;
253
254  struct sockaddr t_laddr;          /* Source address of tunnel */
255  struct sockaddr whereto;          /* Destination of tunnel */
256  struct sockaddr wherefrom;        /* Source of tunnel */
257  struct sockaddr_in *to;
258
259  char buf[0x2000];                 /* Packets buffer */
260  struct ip *ip = (struct ip *)buf;
261
262  fd_set rfds;                      /* File descriptors for select() */
263  int nfds;                         /* Return from select() */
264  int lastfd;                       /* highest fd we care about */
265
266
267  while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
268    switch (c) {
269    case 'd':
270      to_point = optarg;
271      break;
272    case 's':
273      point_to = optarg;
274      break;
275    case 't':
276      dev_name = optarg;
277      break;
278    case 'p':
279      protocol = optarg;
280      break;
281    }
282  }
283  argc -= optind;
284  argv += optind;
285
286  if ((argc != 1 && argc != 2) || (dev_name == NULL) ||
287      (point_to == NULL) || (to_point == NULL)) {
288    usage();
289  }
290
291  if(protocol == NULL)
292      protnum = 94;
293  else
294      protnum = atoi(protocol);
295
296  if (argc == 1) {
297      target = *argv;
298  } else {
299      source = *argv++; target = *argv;
300  }
301
302  /* Establish logging through 'syslog' */
303  openlog("nos-tun", LOG_PID, LOG_DAEMON);
304
305  if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
306    closelog();
307    exit(2);
308  }
309
310  if(tun_open(dev_name, &t_laddr, to_point)) {
311    closelog();
312    exit(3);
313  }
314
315  to = (struct sockaddr_in *)&whereto;
316  if(Set_address(target, to))
317    Finish(4);
318
319  if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
320    syslog(LOG_ERR,"can't open socket - %m");
321    Finish(5);
322  }
323
324  if (source) {
325	if (Set_address(source, (struct sockaddr_in *)&wherefrom))
326	  Finish(9);
327    if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
328	  syslog(LOG_ERR, "can't bind source address - %m");
329	  Finish(10);
330	}
331  }
332
333  if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
334    syslog(LOG_ERR,"can't connect to target - %m");
335    close(net);
336    Finish(6);
337  }
338
339  /*  Demonize it */
340  daemon(0,0);
341
342  /* Install signal handlers */
343  (void)signal(SIGHUP,Finish);
344  (void)signal(SIGINT,Finish);
345  (void)signal(SIGTERM,Finish);
346
347  if (tun > net)
348	lastfd = tun;
349  else
350	lastfd = net;
351
352  for (;;) {
353    /* Set file descriptors for select() */
354    FD_ZERO(&rfds);
355    FD_SET(tun,&rfds); FD_SET(net,&rfds);
356
357    nfds = select(lastfd+1,&rfds,NULL,NULL,NULL);
358    if(nfds < 0) {
359      syslog(LOG_ERR,"interrupted select");
360      close(net);
361      Finish(7);
362    }
363    if(nfds == 0) {         /* Impossible ? */
364      syslog(LOG_ERR,"timeout in select");
365      close(net);
366      Finish(8);
367    }
368
369
370    if(FD_ISSET(net,&rfds)) {
371      /* Read from socket ... */
372      len = read(net, buf, sizeof(buf));
373      /* Check if this is "our" packet */
374      if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
375	/* ... skip encapsulation headers ... */
376	ipoff = (ip->ip_hl << 2);
377	/* ... and write to tun-device */
378	write(tun,buf+ipoff,len-ipoff);
379      }
380    }
381
382    if(FD_ISSET(tun,&rfds)) {
383      /* Read from tun ... */
384      len = read(tun, buf, sizeof(buf));
385      /* ... and send to network */
386      if(send(net, buf, len,0) <= 0) {
387	syslog(LOG_ERR,"can't send - %m");
388      }
389    }
390  }
391}
392
393static void
394usage(void)
395{
396	fprintf(stderr,
397"usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n");
398	exit(1);
399}
400
401