1 /*
2 * bootpgw.c - BOOTP GateWay
3 * This program forwards BOOTP Request packets to a BOOTP server.
4 */
5
6 /************************************************************************
7 Copyright 1988, 1991 by Carnegie Mellon University
8
9 All Rights Reserved
10
11 Permission to use, copy, modify, and distribute this software and its
12 documentation for any purpose and without fee is hereby granted, provided
13 that the above copyright notice appear in all copies and that both that
14 copyright notice and this permission notice appear in supporting
15 documentation, and that the name of Carnegie Mellon University not be used
16 in advertising or publicity pertaining to distribution of the software
17 without specific, written prior permission.
18
19 CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
20 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
21 IN NO EVENT SHALL CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
22 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
23 PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
24 ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
25 SOFTWARE.
26 ************************************************************************/
27
28 /*
29 * BOOTPGW is typically used to forward BOOTP client requests from
30 * one subnet to a BOOTP server on a different subnet.
31 */
32
33 #include <sys/cdefs.h>
34 #include <sys/types.h>
35 #include <sys/param.h>
36 #include <sys/socket.h>
37 #include <sys/ioctl.h>
38 #include <sys/file.h>
39 #include <sys/time.h>
40 #include <sys/stat.h>
41 #include <sys/utsname.h>
42
43 #include <net/if.h>
44 #include <netinet/in.h>
45 #include <arpa/inet.h> /* inet_ntoa */
46
47 #ifndef NO_UNISTD
48 #include <unistd.h>
49 #endif
50
51 #include <err.h>
52 #include <stdlib.h>
53 #include <signal.h>
54 #include <stdio.h>
55 #include <string.h>
56 #include <errno.h>
57 #include <ctype.h>
58 #include <netdb.h>
59 #include <paths.h>
60 #include <syslog.h>
61 #include <assert.h>
62
63 #ifdef NO_SETSID
64 # include <fcntl.h> /* for O_RDONLY, etc */
65 #endif
66
67 #include "bootp.h"
68 #include "getif.h"
69 #include "hwaddr.h"
70 #include "report.h"
71 #include "patchlevel.h"
72
73 /* Local definitions: */
74 #define MAX_MSG_SIZE (3*512) /* Maximum packet size */
75 #define TRUE 1
76 #define FALSE 0
77 #define get_network_errmsg get_errmsg
78
79
80
81 /*
82 * Externals, forward declarations, and global variables
83 */
84
85 static void usage(void) __dead2;
86 static void handle_reply(void);
87 static void handle_request(void);
88
89 /*
90 * IP port numbers for client and server obtained from /etc/services
91 */
92
93 u_short bootps_port, bootpc_port;
94
95
96 /*
97 * Internet socket and interface config structures
98 */
99
100 struct sockaddr_in bind_addr; /* Listening */
101 struct sockaddr_in recv_addr; /* Packet source */
102 struct sockaddr_in send_addr; /* destination */
103
104
105 /*
106 * option defaults
107 */
108 int debug = 0; /* Debugging flag (level) */
109 struct timeval actualtimeout =
110 { /* fifteen minutes */
111 15 * 60L, /* tv_sec */
112 0 /* tv_usec */
113 };
114 u_char maxhops = 4; /* Number of hops allowed for requests. */
115 u_int minwait = 3; /* Number of seconds client must wait before
116 its bootrequest packets are forwarded. */
117 int arpmod = TRUE; /* modify the ARP table */
118
119 /*
120 * General
121 */
122
123 int s; /* Socket file descriptor */
124 char *pktbuf; /* Receive packet buffer */
125 int pktlen;
126 char *progname;
127 char *servername;
128 int32 server_ipa; /* Real server IP address, network order. */
129
130 struct in_addr my_ip_addr;
131
132 struct utsname my_uname;
133 char *hostname;
134
135
136
137
138
139 /*
140 * Initialization such as command-line processing is done and then the
141 * main server loop is started.
142 */
143
144 int
main(int argc,char ** argv)145 main(int argc, char **argv)
146 {
147 struct timeval *timeout;
148 struct bootp *bp;
149 struct servent *servp;
150 struct hostent *hep;
151 char *stmp;
152 int n, ba_len, ra_len;
153 int nfound, readfds;
154 int standalone;
155
156 progname = strrchr(argv[0], '/');
157 if (progname) progname++;
158 else progname = argv[0];
159
160 /*
161 * Initialize logging.
162 */
163 report_init(0); /* uses progname */
164
165 /*
166 * Log startup
167 */
168 report(LOG_INFO, "version %s.%d", VERSION, PATCHLEVEL);
169
170 /* Debugging for compilers with struct padding. */
171 assert(sizeof(struct bootp) == BP_MINPKTSZ);
172
173 /* Get space for receiving packets and composing replies. */
174 pktbuf = malloc(MAX_MSG_SIZE);
175 if (!pktbuf) {
176 report(LOG_ERR, "malloc failed");
177 exit(1);
178 }
179 bp = (struct bootp *) pktbuf;
180
181 /*
182 * Check to see if a socket was passed to us from inetd.
183 *
184 * Use getsockname() to determine if descriptor 0 is indeed a socket
185 * (and thus we are probably a child of inetd) or if it is instead
186 * something else and we are running standalone.
187 */
188 s = 0;
189 ba_len = sizeof(bind_addr);
190 bzero((char *) &bind_addr, ba_len);
191 errno = 0;
192 standalone = TRUE;
193 if (getsockname(s, (struct sockaddr *) &bind_addr, &ba_len) == 0) {
194 /*
195 * Descriptor 0 is a socket. Assume we are a child of inetd.
196 */
197 if (bind_addr.sin_family == AF_INET) {
198 standalone = FALSE;
199 bootps_port = ntohs(bind_addr.sin_port);
200 } else {
201 /* Some other type of socket? */
202 report(LOG_INFO, "getsockname: not an INET socket");
203 }
204 }
205 /*
206 * Set defaults that might be changed by option switches.
207 */
208 stmp = NULL;
209 timeout = &actualtimeout;
210
211 if (uname(&my_uname) < 0)
212 errx(1, "can't get hostname");
213 hostname = my_uname.nodename;
214
215 hep = gethostbyname(hostname);
216 if (!hep) {
217 printf("Can not get my IP address\n");
218 exit(1);
219 }
220 bcopy(hep->h_addr, (char *)&my_ip_addr, sizeof(my_ip_addr));
221
222 /*
223 * Read switches.
224 */
225 for (argc--, argv++; argc > 0; argc--, argv++) {
226 if (argv[0][0] != '-')
227 break;
228 switch (argv[0][1]) {
229
230 case 'a': /* don't modify the ARP table */
231 arpmod = FALSE;
232 break;
233 case 'd': /* debug level */
234 if (argv[0][2]) {
235 stmp = &(argv[0][2]);
236 } else if (argv[1] && argv[1][0] == '-') {
237 /*
238 * Backwards-compatible behavior:
239 * no parameter, so just increment the debug flag.
240 */
241 debug++;
242 break;
243 } else {
244 argc--;
245 argv++;
246 stmp = argv[0];
247 }
248 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) {
249 warnx("invalid debug level");
250 break;
251 }
252 debug = n;
253 break;
254
255 case 'h': /* hop count limit */
256 if (argv[0][2]) {
257 stmp = &(argv[0][2]);
258 } else {
259 argc--;
260 argv++;
261 stmp = argv[0];
262 }
263 if (!stmp || (sscanf(stmp, "%d", &n) != 1) ||
264 (n < 0) || (n > 16))
265 {
266 warnx("invalid hop count limit");
267 break;
268 }
269 maxhops = (u_char)n;
270 break;
271
272 case 'i': /* inetd mode */
273 standalone = FALSE;
274 break;
275
276 case 's': /* standalone mode */
277 standalone = TRUE;
278 break;
279
280 case 't': /* timeout */
281 if (argv[0][2]) {
282 stmp = &(argv[0][2]);
283 } else {
284 argc--;
285 argv++;
286 stmp = argv[0];
287 }
288 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) {
289 warnx("invalid timeout specification");
290 break;
291 }
292 actualtimeout.tv_sec = (int32) (60 * n);
293 /*
294 * If the actual timeout is zero, pass a NULL pointer
295 * to select so it blocks indefinitely, otherwise,
296 * point to the actual timeout value.
297 */
298 timeout = (n > 0) ? &actualtimeout : NULL;
299 break;
300
301 case 'w': /* wait time */
302 if (argv[0][2]) {
303 stmp = &(argv[0][2]);
304 } else {
305 argc--;
306 argv++;
307 stmp = argv[0];
308 }
309 if (!stmp || (sscanf(stmp, "%d", &n) != 1) ||
310 (n < 0) || (n > 60))
311 {
312 warnx("invalid wait time");
313 break;
314 }
315 minwait = (u_int)n;
316 break;
317
318 default:
319 warnx("unknown switch: -%c", argv[0][1]);
320 usage();
321 break;
322
323 } /* switch */
324 } /* for args */
325
326 /* Make sure server name argument is suplied. */
327 servername = argv[0];
328 if (!servername) {
329 warnx("missing server name");
330 usage();
331 }
332 /*
333 * Get address of real bootp server.
334 */
335 if (isdigit(servername[0]))
336 server_ipa = inet_addr(servername);
337 else {
338 hep = gethostbyname(servername);
339 if (!hep)
340 errx(1, "can't get addr for %s", servername);
341 bcopy(hep->h_addr, (char *)&server_ipa, sizeof(server_ipa));
342 }
343
344 if (standalone) {
345 /*
346 * Go into background and disassociate from controlling terminal.
347 * XXX - This is not the POSIX way (Should use setsid). -gwr
348 */
349 if (debug < 3) {
350 if (fork())
351 exit(0);
352 #ifdef NO_SETSID
353 setpgrp(0,0);
354 #ifdef TIOCNOTTY
355 n = open(_PATH_TTY, O_RDWR);
356 if (n >= 0) {
357 ioctl(n, TIOCNOTTY, (char *) 0);
358 (void) close(n);
359 }
360 #endif /* TIOCNOTTY */
361 #else /* SETSID */
362 if (setsid() < 0)
363 perror("setsid");
364 #endif /* SETSID */
365 } /* if debug < 3 */
366 /*
367 * Nuke any timeout value
368 */
369 timeout = NULL;
370
371 /*
372 * Here, bootpd would do:
373 * chdir
374 * tzone_init
375 * rdtab_init
376 * readtab
377 */
378
379 /*
380 * Create a socket.
381 */
382 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
383 report(LOG_ERR, "socket: %s", get_network_errmsg());
384 exit(1);
385 }
386 /*
387 * Get server's listening port number
388 */
389 servp = getservbyname("bootps", "udp");
390 if (servp) {
391 bootps_port = ntohs((u_short) servp->s_port);
392 } else {
393 bootps_port = (u_short) IPPORT_BOOTPS;
394 report(LOG_ERR,
395 "bootps/udp: unknown service -- using port %d",
396 bootps_port);
397 }
398
399 /*
400 * Bind socket to BOOTPS port.
401 */
402 bind_addr.sin_family = AF_INET;
403 bind_addr.sin_port = htons(bootps_port);
404 bind_addr.sin_addr.s_addr = INADDR_ANY;
405 if (bind(s, (struct sockaddr *) &bind_addr,
406 sizeof(bind_addr)) < 0)
407 {
408 report(LOG_ERR, "bind: %s", get_network_errmsg());
409 exit(1);
410 }
411 } /* if standalone */
412 /*
413 * Get destination port number so we can reply to client
414 */
415 servp = getservbyname("bootpc", "udp");
416 if (servp) {
417 bootpc_port = ntohs(servp->s_port);
418 } else {
419 report(LOG_ERR,
420 "bootpc/udp: unknown service -- using port %d",
421 IPPORT_BOOTPC);
422 bootpc_port = (u_short) IPPORT_BOOTPC;
423 }
424
425 /* no signal catchers */
426
427 /*
428 * Process incoming requests.
429 */
430 for (;;) {
431 struct timeval tv;
432
433 readfds = 1 << s;
434 if (timeout)
435 tv = *timeout;
436
437 nfound = select(s + 1, (fd_set *)&readfds, NULL, NULL,
438 (timeout) ? &tv : NULL);
439 if (nfound < 0) {
440 if (errno != EINTR) {
441 report(LOG_ERR, "select: %s", get_errmsg());
442 }
443 continue;
444 }
445 if (!(readfds & (1 << s))) {
446 report(LOG_INFO, "exiting after %ld minutes of inactivity",
447 (long)(actualtimeout.tv_sec / 60));
448 exit(0);
449 }
450 ra_len = sizeof(recv_addr);
451 n = recvfrom(s, pktbuf, MAX_MSG_SIZE, 0,
452 (struct sockaddr *) &recv_addr, &ra_len);
453 if (n <= 0) {
454 continue;
455 }
456 if (debug > 3) {
457 report(LOG_INFO, "recvd pkt from IP addr %s",
458 inet_ntoa(recv_addr.sin_addr));
459 }
460 if (n < sizeof(struct bootp)) {
461 if (debug) {
462 report(LOG_INFO, "received short packet");
463 }
464 continue;
465 }
466 pktlen = n;
467
468 switch (bp->bp_op) {
469 case BOOTREQUEST:
470 handle_request();
471 break;
472 case BOOTREPLY:
473 handle_reply();
474 break;
475 }
476 }
477 return 0;
478 }
479
480
481
482
483 /*
484 * Print "usage" message and exit
485 */
486
487 static void
usage()488 usage()
489 {
490 fprintf(stderr,
491 "usage: bootpgw [-a] [-i | -s] [-d level] [-h count] [-t timeout]\n"
492 " [-w time] server\n");
493 fprintf(stderr, "\t -a\tdon't modify ARP table\n");
494 fprintf(stderr, "\t -d n\tset debug level\n");
495 fprintf(stderr, "\t -h n\tset max hop count\n");
496 fprintf(stderr, "\t -i\tforce inetd mode (run as child of inetd)\n");
497 fprintf(stderr, "\t -s\tforce standalone mode (run without inetd)\n");
498 fprintf(stderr, "\t -t n\tset inetd exit timeout to n minutes\n");
499 fprintf(stderr, "\t -w n\tset min wait time (secs)\n");
500 exit(1);
501 }
502
503
504
505 /*
506 * Process BOOTREQUEST packet.
507 *
508 * Note, this just forwards the request to a real server.
509 */
510 static void
handle_request()511 handle_request()
512 {
513 struct bootp *bp = (struct bootp *) pktbuf;
514 u_short secs;
515 u_char hops;
516
517 /* XXX - SLIP init: Set bp_ciaddr = recv_addr here? */
518
519 if (debug) {
520 report(LOG_INFO, "request from %s",
521 inet_ntoa(recv_addr.sin_addr));
522 }
523 /* Has the client been waiting long enough? */
524 secs = ntohs(bp->bp_secs);
525 if (secs < minwait)
526 return;
527
528 /* Has this packet hopped too many times? */
529 hops = bp->bp_hops;
530 if (++hops > maxhops) {
531 report(LOG_NOTICE, "request from %s reached hop limit",
532 inet_ntoa(recv_addr.sin_addr));
533 return;
534 }
535 bp->bp_hops = hops;
536
537 /*
538 * Here one might discard a request from the same subnet as the
539 * real server, but we can assume that the real server will send
540 * a reply to the client before it waits for minwait seconds.
541 */
542
543 /* If gateway address is not set, put in local interface addr. */
544 if (bp->bp_giaddr.s_addr == 0) {
545 #if 0 /* BUG */
546 struct sockaddr_in *sip;
547 struct ifreq *ifr;
548 /*
549 * XXX - This picks the wrong interface when the receive addr
550 * is the broadcast address. There is no portable way to
551 * find out which interface a broadcast was received on. -gwr
552 * (Thanks to <[email protected]> for finding this bug!)
553 */
554 ifr = getif(s, &recv_addr.sin_addr);
555 if (!ifr) {
556 report(LOG_NOTICE, "no interface for request from %s",
557 inet_ntoa(recv_addr.sin_addr));
558 return;
559 }
560 sip = (struct sockaddr_in *) &(ifr->ifr_addr);
561 bp->bp_giaddr = sip->sin_addr;
562 #else /* BUG */
563 /*
564 * XXX - Just set "giaddr" to our "official" IP address.
565 * RFC 1532 says giaddr MUST be set to the address of the
566 * interface on which the request was received. Setting
567 * it to our "default" IP address is not strictly correct,
568 * but is good enough to allow the real BOOTP server to
569 * get the reply back here. Then, before we forward the
570 * reply to the client, the giaddr field is corrected.
571 * (In case the client uses giaddr, which it should not.)
572 * See handle_reply()
573 */
574 bp->bp_giaddr = my_ip_addr;
575 #endif /* BUG */
576
577 /*
578 * XXX - DHCP says to insert a subnet mask option into the
579 * options area of the request (if vendor magic == std).
580 */
581 }
582 /* Set up socket address for send. */
583 send_addr.sin_family = AF_INET;
584 send_addr.sin_port = htons(bootps_port);
585 send_addr.sin_addr.s_addr = server_ipa;
586
587 /* Send reply with same size packet as request used. */
588 if (sendto(s, pktbuf, pktlen, 0,
589 (struct sockaddr *) &send_addr,
590 sizeof(send_addr)) < 0)
591 {
592 report(LOG_ERR, "sendto: %s", get_network_errmsg());
593 }
594 }
595
596
597
598 /*
599 * Process BOOTREPLY packet.
600 */
601 static void
handle_reply()602 handle_reply()
603 {
604 struct bootp *bp = (struct bootp *) pktbuf;
605 struct ifreq *ifr;
606 struct sockaddr_in *sip;
607 unsigned char *ha;
608 int len, haf;
609
610 if (debug) {
611 report(LOG_INFO, " reply for %s",
612 inet_ntoa(bp->bp_yiaddr));
613 }
614 /* Make sure client is directly accessible. */
615 ifr = getif(s, &(bp->bp_yiaddr));
616 if (!ifr) {
617 report(LOG_NOTICE, "no interface for reply to %s",
618 inet_ntoa(bp->bp_yiaddr));
619 return;
620 }
621 #if 1 /* Experimental (see BUG above) */
622 /* #ifdef CATER_TO_OLD_CLIENTS ? */
623 /*
624 * The giaddr field has been set to our "default" IP address
625 * which might not be on the same interface as the client.
626 * In case the client looks at giaddr, (which it should not)
627 * giaddr is now set to the address of the correct interface.
628 */
629 sip = (struct sockaddr_in *) &(ifr->ifr_addr);
630 bp->bp_giaddr = sip->sin_addr;
631 #endif
632
633 /* Set up socket address for send to client. */
634 send_addr.sin_family = AF_INET;
635 send_addr.sin_addr = bp->bp_yiaddr;
636 send_addr.sin_port = htons(bootpc_port);
637
638 if (arpmod) {
639 /* Create an ARP cache entry for the client. */
640 ha = bp->bp_chaddr;
641 len = bp->bp_hlen;
642 struct in_addr dst;
643
644 if (len > MAXHADDRLEN)
645 len = MAXHADDRLEN;
646 haf = (int) bp->bp_htype;
647 if (haf == 0)
648 haf = HTYPE_ETHERNET;
649
650 if (debug > 1)
651 report(LOG_INFO, "setarp %s - %s",
652 inet_ntoa(dst), haddrtoa(ha, len));
653 setarp(s, &dst, haf, ha, len);
654 }
655
656 /* Send reply with same size packet as request used. */
657 if (sendto(s, pktbuf, pktlen, 0,
658 (struct sockaddr *) &send_addr,
659 sizeof(send_addr)) < 0)
660 {
661 report(LOG_ERR, "sendto: %s", get_network_errmsg());
662 }
663 }
664
665 /*
666 * Local Variables:
667 * tab-width: 4
668 * c-indent-level: 4
669 * c-argdecl-indent: 4
670 * c-continued-statement-offset: 4
671 * c-continued-brace-offset: -4
672 * c-label-offset: -4
673 * c-brace-offset: 0
674 * End:
675 */
676