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 */
29
30 /*
31 * 'nos-tun' program configure tunN interface as a point-to-point
32 * connection with two "pseudo"-addresses between this host and
33 * 'target'.
34 *
35 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP)
36 * (known as NOS-incapsulation in CISCO-routers' terminology).
37 *
38 * 'nos-tun' can works with itself and CISCO-routers.
39 * (It may also work with Linux 'nos-tun's, but
40 * I have no Linux system here to test with).
41 *
42 * BUGS (or features ?):
43 * - you must specify ONE of the target host's addresses
44 * ( nos-tun sends and accepts packets only to/from this
45 * address )
46 * - there can be only ONE tunnel between two hosts,
47 * more precisely - between given host and (one of)
48 * target hosts' address(es)
49 * (and why do you want more ?)
50 */
51
52 /*
53 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com>
54 * I added a new flag for ip protocol number.
55 * We are using 4 as protocol number in ampr.org.
56 */
57
58 #include <fcntl.h>
59 #include <netdb.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <syslog.h>
64 #include <sys/signal.h>
65 #include <sys/socket.h>
66 #include <sys/ioctl.h>
67 #include <netinet/in.h>
68 #include <netinet/in_systm.h>
69 #include <netinet/ip.h>
70 #include <net/if.h>
71 #include <net/tun/if_tun.h>
72 #include <arpa/inet.h>
73 #include <unistd.h>
74
75 /* Tunnel interface configuration stuff */
76 static struct ifaliasreq ifra;
77 static struct ifreq ifrq;
78
79 /* Tun(4) device autocloner */
80 static const char *tun_dev = "/dev/tun";
81
82 /* Global descriptors */
83 int net; /* socket descriptor */
84 int tun; /* tunnel descriptor */
85
86 static void usage(void);
87
88 static int
Set_address(char * addr,struct sockaddr_in * my_sin)89 Set_address(char *addr, struct sockaddr_in *my_sin)
90 {
91 struct hostent *hp;
92
93 bzero(my_sin, sizeof(struct sockaddr));
94 my_sin->sin_family = AF_INET;
95 if((my_sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) {
96 hp = gethostbyname(addr);
97 if (!hp) {
98 syslog(LOG_ERR,"unknown host %s", addr);
99 return 1;
100 }
101 my_sin->sin_family = hp->h_addrtype;
102 bcopy(hp->h_addr, (caddr_t)&my_sin->sin_addr, hp->h_length);
103 }
104 return 0;
105 }
106
107 static int
tun_open(struct sockaddr * ouraddr,char * theiraddr)108 tun_open(struct sockaddr *ouraddr, char *theiraddr)
109 {
110 int s;
111 struct sockaddr_in *my_sin;
112
113 /* Open tun device */
114 tun = open(tun_dev, O_RDWR);
115 if (tun < 0) {
116 syslog(LOG_ERR,"can't open %s - %m",tun_dev);
117 return(1);
118 }
119
120 /*
121 * At first, name the interface.
122 */
123 bzero((char *)&ifra, sizeof(ifra));
124 bzero((char *)&ifrq, sizeof(ifrq));
125
126 if (ioctl(tun, TUNGIFNAME, &ifrq) < 0) {
127 syslog(LOG_ERR,"can't get tun interface name - %m");
128 goto tunc_return;
129 }
130 strlcpy(ifra.ifra_name, ifrq.ifr_name, IFNAMSIZ);
131
132 s = socket(AF_INET, SOCK_DGRAM, 0);
133 if (s < 0) {
134 syslog(LOG_ERR,"can't open socket - %m");
135 goto tunc_return;
136 }
137
138 /*
139 * Delete (previous) addresses for interface
140 *
141 * !!!!
142 * On FreeBSD this ioctl returns error
143 * when tunN have no addresses, so - log and ignore it.
144 */
145 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
146 syslog(LOG_ERR,"SIOCDIFADDR - %m");
147 }
148
149 /*
150 * Set interface address
151 */
152 my_sin = (struct sockaddr_in *)&(ifra.ifra_addr);
153 bcopy(ouraddr, my_sin, sizeof(struct sockaddr_in));
154 my_sin->sin_len = sizeof(*my_sin);
155
156 /*
157 * Set destination address
158 */
159 my_sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
160 if (Set_address(theiraddr, my_sin)) {
161 syslog(LOG_ERR,"bad destination address: %s",theiraddr);
162 goto stunc_return;
163 }
164 my_sin->sin_len = sizeof(*my_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");
185
186 stunc_return:
187 close(s);
188 tunc_return:
189 close(tun);
190 return(1);
191 }
192
193 static void
Finish(int signum)194 Finish(int signum)
195 {
196 int s;
197
198 syslog(LOG_INFO,"exiting");
199
200 close(net);
201
202 s = socket(AF_INET, SOCK_DGRAM, 0);
203 if (s < 0) {
204 syslog(LOG_ERR,"can't open socket - %m");
205 goto closing_tun;
206 }
207
208 /*
209 * Shut down interface.
210 */
211 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
212 syslog(LOG_ERR,"can't get interface flags - %m");
213 goto closing_fds;
214 }
215
216 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
217 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
218 syslog(LOG_ERR,"can't set interface DOWN - %m");
219 goto closing_fds;
220 }
221
222 /*
223 * Delete addresses for interface
224 */
225 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
226 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
227 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
228 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
229 syslog(LOG_ERR,"can't delete interface's addresses - %m");
230 }
231
232 closing_fds:
233 close(s);
234 closing_tun:
235 close(tun);
236 closelog();
237 exit(signum);
238 }
239
240 int
main(int argc,char ** argv)241 main(int argc, char **argv)
242 {
243 int c, len, ipoff;
244
245 char *point_to = NULL;
246 char *to_point = NULL;
247 char *target;
248 char *protocol = NULL;
249 int protnum;
250
251 struct sockaddr t_laddr; /* Source address of tunnel */
252 struct sockaddr whereto; /* Destination of tunnel */
253 struct sockaddr_in *to;
254
255 char buf[0x2000]; /* Packets buffer */
256 struct ip *ip = (struct ip *)buf;
257
258 fd_set rfds, wfds, efds; /* File descriptors for select() */
259 int nfds; /* Return from select() */
260
261 while ((c = getopt(argc, argv, "d:s:p:")) != -1) {
262 switch (c) {
263 case 'd':
264 to_point = optarg;
265 break;
266 case 's':
267 point_to = optarg;
268 break;
269 case 'p':
270 protocol = optarg;
271 break;
272 }
273 }
274 argc -= optind;
275 argv += optind;
276
277 if (argc != 1 || (point_to == NULL) || (to_point == NULL))
278 usage();
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(&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
usage(void)365 usage(void)
366 {
367 fprintf(stderr, "usage: nos-tun -s <source_addr> -d <dest_addr> "
368 "-p <protocol_number> <target_addr>\n");
369 exit(1);
370 }
371
372