1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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 #include <sys/types.h>
61 #include <sys/ioctl.h>
62 #include <sys/signal.h>
63 #include <sys/socket.h>
64
65 #include <net/if.h>
66 #include <netinet/in.h>
67 #include <netinet/in_systm.h>
68 #include <netinet/ip.h>
69
70 #include <arpa/inet.h>
71 #include <fcntl.h>
72 #include <netdb.h>
73 #include <stdio.h>
74 #include <stdlib.h>
75 #include <string.h>
76 #include <syslog.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(void) __dead2;
88
89 static int
Set_address(char * addr,struct sockaddr_in * sin)90 Set_address(char *addr, struct sockaddr_in *sin)
91 {
92 struct hostent *hp;
93
94 bzero((char *)sin, sizeof(struct sockaddr));
95 sin->sin_family = AF_INET;
96 if((sin->sin_addr.s_addr = inet_addr(addr)) == INADDR_NONE) {
97 hp = gethostbyname(addr);
98 if (!hp) {
99 syslog(LOG_ERR,"unknown host %s", addr);
100 return 1;
101 }
102 sin->sin_family = hp->h_addrtype;
103 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
104 }
105 return 0;
106 }
107
108 static int
tun_open(char * dev_name,struct sockaddr * ouraddr,char * theiraddr)109 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr)
110 {
111 int s;
112 struct sockaddr_in *sin;
113
114 /* Open tun device */
115 tun = open(dev_name, O_RDWR);
116 if (tun < 0) {
117 syslog(LOG_ERR,"can't open %s - %m", dev_name);
118 return(1);
119 }
120
121 /*
122 * At first, name the interface.
123 */
124 bzero((char *)&ifra, sizeof(ifra));
125 bzero((char *)&ifrq, sizeof(ifrq));
126
127 strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ);
128 strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ);
129
130 s = socket(AF_INET, SOCK_DGRAM, 0);
131 if (s < 0) {
132 syslog(LOG_ERR,"can't open socket - %m");
133 goto tunc_return;
134 }
135
136 /*
137 * Delete (previous) addresses for interface
138 *
139 * !!!!
140 * On FreeBSD this ioctl returns error
141 * when tunN have no addresses, so - log and ignore it.
142 *
143 */
144 if (ioctl(s, SIOCDIFADDR, &ifrq) < 0) {
145 syslog(LOG_ERR,"SIOCDIFADDR - %m");
146 }
147
148 /*
149 * Set interface address
150 */
151 sin = (struct sockaddr_in *)&(ifra.ifra_addr);
152 bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
153 sin->sin_len = sizeof(*sin);
154
155 /*
156 * Set destination address
157 */
158 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
159 if(Set_address(theiraddr,sin)) {
160 syslog(LOG_ERR,"bad destination address: %s",theiraddr);
161 goto stunc_return;
162 }
163 sin->sin_len = sizeof(*sin);
164
165 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
166 syslog(LOG_ERR,"can't set interface address - %m");
167 goto stunc_return;
168 }
169
170 /*
171 * Now, bring up the interface.
172 */
173 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
174 syslog(LOG_ERR,"can't get interface flags - %m");
175 goto stunc_return;
176 }
177
178 ifrq.ifr_flags |= IFF_UP;
179 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
180 close(s);
181 return(0);
182 }
183 syslog(LOG_ERR,"can't set interface UP - %m");
184 stunc_return:
185 close(s);
186 tunc_return:
187 close(tun);
188 return(1);
189 }
190
191 static void
Finish(int signum)192 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(&ifrq.ifr_addr, sizeof(ifrq.ifr_addr));
224 if (ioctl(s, SIOCDIFADDR, &ifrq) < 0) {
225 syslog(LOG_ERR,"can't delete interface's addresses - %m");
226 }
227 closing_fds:
228 close(s);
229 closing_tun:
230 close(tun);
231 closelog();
232 exit(signum);
233 }
234
main(int argc,char ** argv)235 int main (int argc, char **argv)
236 {
237 int c, len, ipoff;
238
239 char *dev_name = NULL;
240 char *point_to = NULL;
241 char *to_point = NULL;
242 char *target;
243 char *source = NULL;
244 char *protocol = NULL;
245 int protnum;
246
247 struct sockaddr t_laddr; /* Source address of tunnel */
248 struct sockaddr whereto; /* Destination of tunnel */
249 struct sockaddr wherefrom; /* Source of tunnel */
250 struct sockaddr_in *to;
251
252 char buf[0x2000]; /* Packets buffer */
253 struct ip *ip = (struct ip *)buf;
254
255 fd_set rfds; /* File descriptors for select() */
256 int nfds; /* Return from select() */
257 int lastfd; /* highest fd we care about */
258
259
260 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
261 switch (c) {
262 case 'd':
263 to_point = optarg;
264 break;
265 case 's':
266 point_to = optarg;
267 break;
268 case 't':
269 dev_name = optarg;
270 break;
271 case 'p':
272 protocol = optarg;
273 break;
274 }
275 }
276 argc -= optind;
277 argv += optind;
278
279 if ((argc != 1 && argc != 2) || (dev_name == NULL) ||
280 (point_to == NULL) || (to_point == NULL)) {
281 usage();
282 }
283
284 if(protocol == NULL)
285 protnum = 94;
286 else
287 protnum = atoi(protocol);
288
289 if (argc == 1) {
290 target = *argv;
291 } else {
292 source = *argv++; target = *argv;
293 }
294
295 /* Establish logging through 'syslog' */
296 openlog("nos-tun", LOG_PID, LOG_DAEMON);
297
298 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
299 closelog();
300 exit(2);
301 }
302
303 if(tun_open(dev_name, &t_laddr, to_point)) {
304 closelog();
305 exit(3);
306 }
307
308 to = (struct sockaddr_in *)&whereto;
309 if(Set_address(target, to))
310 Finish(4);
311
312 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
313 syslog(LOG_ERR,"can't open socket - %m");
314 Finish(5);
315 }
316
317 if (source) {
318 if (Set_address(source, (struct sockaddr_in *)&wherefrom))
319 Finish(9);
320 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
321 syslog(LOG_ERR, "can't bind source address - %m");
322 Finish(10);
323 }
324 }
325
326 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
327 syslog(LOG_ERR,"can't connect to target - %m");
328 close(net);
329 Finish(6);
330 }
331
332 /* Demonize it */
333 daemon(0,0);
334
335 /* Install signal handlers */
336 (void)signal(SIGHUP,Finish);
337 (void)signal(SIGINT,Finish);
338 (void)signal(SIGTERM,Finish);
339
340 if (tun > net)
341 lastfd = tun;
342 else
343 lastfd = net;
344
345 for (;;) {
346 /* Set file descriptors for select() */
347 FD_ZERO(&rfds);
348 FD_SET(tun,&rfds); FD_SET(net,&rfds);
349
350 nfds = select(lastfd+1,&rfds,NULL,NULL,NULL);
351 if(nfds < 0) {
352 syslog(LOG_ERR,"interrupted select");
353 close(net);
354 Finish(7);
355 }
356 if(nfds == 0) { /* Impossible ? */
357 syslog(LOG_ERR,"timeout in select");
358 close(net);
359 Finish(8);
360 }
361
362
363 if(FD_ISSET(net,&rfds)) {
364 /* Read from socket ... */
365 len = read(net, buf, sizeof(buf));
366 /* Check if this is "our" packet */
367 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
368 /* ... skip encapsulation headers ... */
369 ipoff = (ip->ip_hl << 2);
370 /* ... and write to tun-device */
371 write(tun,buf+ipoff,len-ipoff);
372 }
373 }
374
375 if(FD_ISSET(tun,&rfds)) {
376 /* Read from tun ... */
377 len = read(tun, buf, sizeof(buf));
378 /* ... and send to network */
379 if(send(net, buf, len,0) <= 0) {
380 syslog(LOG_ERR,"can't send - %m");
381 }
382 }
383 }
384 }
385
386 static void
usage(void)387 usage(void)
388 {
389 fprintf(stderr,
390 "usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n");
391 exit(1);
392 }
393
394