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  "$FreeBSD$";
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
92static int
93Set_address(char *addr, struct sockaddr_in *sin)
94{
95  struct hostent *hp;
96
97  bzero((char *)sin, sizeof(struct sockaddr));
98  sin->sin_family = AF_INET;
99  if((sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) {
100    hp = gethostbyname(addr);
101    if (!hp) {
102      syslog(LOG_ERR,"unknown host %s", addr);
103      return 1;
104    }
105    sin->sin_family = hp->h_addrtype;
106    bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
107  }
108  return 0;
109}
110
111static int
112tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr)
113{
114  int s;
115  struct sockaddr_in *sin;
116
117  /* Open tun device */
118  tun = open(dev_name, O_RDWR);
119  if (tun < 0) {
120    syslog(LOG_ERR,"can't open %s - %m", dev_name);
121    return(1);
122  }
123
124  /*
125   * At first, name the interface.
126   */
127  bzero((char *)&ifra, sizeof(ifra));
128  bzero((char *)&ifrq, sizeof(ifrq));
129
130  strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ);
131  strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ);
132
133  s = socket(AF_INET, SOCK_DGRAM, 0);
134  if (s < 0) {
135    syslog(LOG_ERR,"can't open socket - %m");
136    goto tunc_return;
137  }
138
139  /*
140   *  Delete (previous) addresses for interface
141   *
142   *  !!!!
143   *  On FreeBSD this ioctl returns error
144   *  when tunN have no addresses, so - log and ignore it.
145   *
146   */
147  if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
148    syslog(LOG_ERR,"SIOCDIFADDR - %m");
149  }
150
151  /*
152   *  Set interface address
153   */
154  sin = (struct sockaddr_in *)&(ifra.ifra_addr);
155  bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
156  sin->sin_len = sizeof(*sin);
157
158  /*
159   *  Set destination address
160   */
161  sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
162  if(Set_address(theiraddr,sin)) {
163    syslog(LOG_ERR,"bad destination address: %s",theiraddr);
164    goto stunc_return;
165  }
166  sin->sin_len = sizeof(*sin);
167
168  if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
169    syslog(LOG_ERR,"can't set interface address - %m");
170    goto stunc_return;
171  }
172
173  /*
174   *  Now, bring up the interface.
175   */
176  if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
177    syslog(LOG_ERR,"can't get interface flags - %m");
178    goto stunc_return;
179  }
180
181  ifrq.ifr_flags |= IFF_UP;
182  if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
183    close(s);
184    return(0);
185  }
186  syslog(LOG_ERR,"can't set interface UP - %m");
187stunc_return:
188  close(s);
189tunc_return:
190  close(tun);
191  return(1);
192}
193
194static void
195Finish(int signum)
196{
197  int s;
198
199  syslog(LOG_INFO,"exiting");
200
201  close(net);
202
203  s = socket(AF_INET, SOCK_DGRAM, 0);
204  if (s < 0) {
205    syslog(LOG_ERR,"can't open socket - %m");
206    goto closing_tun;
207  }
208
209  /*
210   *  Shut down interface.
211   */
212  if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
213    syslog(LOG_ERR,"can't get interface flags - %m");
214    goto closing_fds;
215  }
216
217  ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
218  if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
219    syslog(LOG_ERR,"can't set interface DOWN - %m");
220    goto closing_fds;
221  }
222
223  /*
224   *  Delete addresses for interface
225   */
226  bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
227  bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
228  bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
229  if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
230    syslog(LOG_ERR,"can't delete interface's addresses - %m");
231  }
232closing_fds:
233  close(s);
234closing_tun:
235  close(tun);
236  closelog();
237  exit(signum);
238}
239
240int main (int argc, char **argv)
241{
242  int  c, len, ipoff;
243
244  char *dev_name = NULL;
245  char *point_to = NULL;
246  char *to_point = NULL;
247  char *target;
248  char *source = NULL;
249  char *protocol = NULL;
250  int protnum;
251
252  struct sockaddr t_laddr;          /* Source address of tunnel */
253  struct sockaddr whereto;          /* Destination of tunnel */
254  struct sockaddr wherefrom;        /* Source of tunnel */
255  struct sockaddr_in *to;
256
257  char buf[0x2000];                 /* Packets buffer */
258  struct ip *ip = (struct ip *)buf;
259
260  fd_set rfds;                      /* File descriptors for select() */
261  int nfds;                         /* Return from select() */
262  int lastfd;                       /* highest fd we care about */
263
264
265  while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
266    switch (c) {
267    case 'd':
268      to_point = optarg;
269      break;
270    case 's':
271      point_to = optarg;
272      break;
273    case 't':
274      dev_name = optarg;
275      break;
276    case 'p':
277      protocol = optarg;
278      break;
279    }
280  }
281  argc -= optind;
282  argv += optind;
283
284  if ((argc != 1 && argc != 2) || (dev_name == NULL) ||
285      (point_to == NULL) || (to_point == NULL)) {
286    usage();
287  }
288
289  if(protocol == NULL)
290      protnum = 94;
291  else
292      protnum = atoi(protocol);
293
294  if (argc == 1) {
295      target = *argv;
296  } else {
297      source = *argv++; target = *argv;
298  }
299
300  /* Establish logging through 'syslog' */
301  openlog("nos-tun", LOG_PID, LOG_DAEMON);
302
303  if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
304    closelog();
305    exit(2);
306  }
307
308  if(tun_open(dev_name, &t_laddr, to_point)) {
309    closelog();
310    exit(3);
311  }
312
313  to = (struct sockaddr_in *)&whereto;
314  if(Set_address(target, to))
315    Finish(4);
316
317  if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
318    syslog(LOG_ERR,"can't open socket - %m");
319    Finish(5);
320  }
321
322  if (source) {
323	if (Set_address(source, (struct sockaddr_in *)&wherefrom))
324	  Finish(9);
325    if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
326	  syslog(LOG_ERR, "can't bind source address - %m");
327	  Finish(10);
328	}
329  }
330
331  if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
332    syslog(LOG_ERR,"can't connect to target - %m");
333    close(net);
334    Finish(6);
335  }
336
337  /*  Demonize it */
338  daemon(0,0);
339
340  /* Install signal handlers */
341  (void)signal(SIGHUP,Finish);
342  (void)signal(SIGINT,Finish);
343  (void)signal(SIGTERM,Finish);
344
345  if (tun > net)
346	lastfd = tun;
347  else
348	lastfd = net;
349
350  for (;;) {
351    /* Set file descriptors for select() */
352    FD_ZERO(&rfds);
353    FD_SET(tun,&rfds); FD_SET(net,&rfds);
354
355    nfds = select(lastfd+1,&rfds,NULL,NULL,NULL);
356    if(nfds < 0) {
357      syslog(LOG_ERR,"interrupted select");
358      close(net);
359      Finish(7);
360    }
361    if(nfds == 0) {         /* Impossible ? */
362      syslog(LOG_ERR,"timeout in select");
363      close(net);
364      Finish(8);
365    }
366
367
368    if(FD_ISSET(net,&rfds)) {
369      /* Read from socket ... */
370      len = read(net, buf, sizeof(buf));
371      /* Check if this is "our" packet */
372      if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
373	/* ... skip encapsulation headers ... */
374	ipoff = (ip->ip_hl << 2);
375	/* ... and write to tun-device */
376	write(tun,buf+ipoff,len-ipoff);
377      }
378    }
379
380    if(FD_ISSET(tun,&rfds)) {
381      /* Read from tun ... */
382      len = read(tun, buf, sizeof(buf));
383      /* ... and send to network */
384      if(send(net, buf, len,0) <= 0) {
385	syslog(LOG_ERR,"can't send - %m");
386      }
387    }
388  }
389}
390
391static void
392usage(void)
393{
394	fprintf(stderr,
395"usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n");
396	exit(1);
397}
398
399