1 /* $NetBSD: rdisc.c,v 1.17 2006/05/09 20:18:09 mrg Exp $ */
2
3 /*
4 * Copyright (c) 1995
5 * The Regents of the University of California. 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, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgment:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include "defs.h"
37 #include <netinet/in_systm.h>
38 #include <netinet/ip.h>
39 #include <netinet/ip_icmp.h>
40
41 #ifdef __NetBSD__
42 __RCSID("$NetBSD: rdisc.c,v 1.17 2006/05/09 20:18:09 mrg Exp $");
43 #elif defined(__FreeBSD__)
44 __RCSID("$FreeBSD$");
45 #else
46 __RCSID("Revision: 2.23 ");
47 #ident "Revision: 2.23 "
48 #endif
49
50 /* router advertisement ICMP packet */
51 struct icmp_ad {
52 u_int8_t icmp_type; /* type of message */
53 u_int8_t icmp_code; /* type sub code */
54 u_int16_t icmp_cksum; /* ones complement cksum of struct */
55 u_int8_t icmp_ad_num; /* # of following router addresses */
56 u_int8_t icmp_ad_asize; /* 2--words in each advertisement */
57 u_int16_t icmp_ad_life; /* seconds of validity */
58 struct icmp_ad_info {
59 n_long icmp_ad_addr;
60 n_long icmp_ad_pref;
61 } icmp_ad_info[1];
62 };
63
64 /* router solicitation ICMP packet */
65 struct icmp_so {
66 u_int8_t icmp_type; /* type of message */
67 u_int8_t icmp_code; /* type sub code */
68 u_int16_t icmp_cksum; /* ones complement cksum of struct */
69 n_long icmp_so_rsvd;
70 };
71
72 union ad_u {
73 struct icmp icmp;
74 struct icmp_ad ad;
75 struct icmp_so so;
76 };
77
78
79 int rdisc_sock = -1; /* router-discovery raw socket */
80 struct interface *rdisc_sock_mcast; /* current multicast interface */
81
82 struct timeval rdisc_timer;
83 int rdisc_ok; /* using solicited route */
84
85
86 #define MAX_ADS 16 /* at least one per interface */
87 struct dr { /* accumulated advertisements */
88 struct interface *dr_ifp;
89 naddr dr_gate; /* gateway */
90 time_t dr_ts; /* when received */
91 time_t dr_life; /* lifetime in host byte order */
92 n_long dr_recv_pref; /* received but biased preference */
93 n_long dr_pref; /* preference adjusted by metric */
94 } *cur_drp, drs[MAX_ADS];
95
96 /* convert between signed, balanced around zero,
97 * and unsigned zero-based preferences */
98 #define SIGN_PREF(p) ((p) ^ MIN_PreferenceLevel)
99 #define UNSIGN_PREF(p) SIGN_PREF(p)
100 /* adjust unsigned preference by interface metric,
101 * without driving it to infinity */
102 #define PREF(p, ifp) ((n_long)(p) <= (n_long)((ifp)->int_metric \
103 + (ifp)->int_adj_outmetric) \
104 ? ((p) != 0 ? 1 : 0) \
105 : (p) - ((ifp)->int_metric + (ifp)->int_adj_outmetric))
106
107 static void rdisc_sort(void);
108
109
110 /* dump an ICMP Router Discovery Advertisement Message
111 */
112 static void
trace_rdisc(const char * act,naddr from,naddr to,struct interface * ifp,union ad_u * p,u_int len)113 trace_rdisc(const char *act,
114 naddr from,
115 naddr to,
116 struct interface *ifp,
117 union ad_u *p,
118 u_int len)
119 {
120 int i;
121 n_long *wp, *lim;
122
123
124 if (!TRACEPACKETS || ftrace == 0)
125 return;
126
127 lastlog();
128
129 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
130 (void)fprintf(ftrace, "%s Router Ad"
131 " from %s to %s via %s life=%d\n",
132 act, naddr_ntoa(from), naddr_ntoa(to),
133 ifp ? ifp->int_name : "?",
134 ntohs(p->ad.icmp_ad_life));
135 if (!TRACECONTENTS)
136 return;
137
138 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
139 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)];
140 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) {
141 (void)fprintf(ftrace, "\t%s preference=%d",
142 naddr_ntoa(wp[0]), (int)ntohl(wp[1]));
143 wp += p->ad.icmp_ad_asize;
144 }
145 (void)fputc('\n',ftrace);
146
147 } else {
148 trace_act("%s Router Solic. from %s to %s via %s value=%#x",
149 act, naddr_ntoa(from), naddr_ntoa(to),
150 ifp ? ifp->int_name : "?",
151 (int)ntohl(p->so.icmp_so_rsvd));
152 }
153 }
154
155 /* prepare Router Discovery socket.
156 */
157 static void
get_rdisc_sock(void)158 get_rdisc_sock(void)
159 {
160 if (rdisc_sock < 0) {
161 rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
162 if (rdisc_sock < 0)
163 BADERR(1,"rdisc_sock = socket()");
164 fix_sock(rdisc_sock,"rdisc_sock");
165 fix_select();
166 }
167 }
168
169
170 /* Pick multicast group for router-discovery socket
171 */
172 void
set_rdisc_mg(struct interface * ifp,int on)173 set_rdisc_mg(struct interface *ifp,
174 int on) /* 0=turn it off */
175 {
176 struct ip_mreq m;
177
178 if (rdisc_sock < 0) {
179 /* Create the raw socket so that we can hear at least
180 * broadcast router discovery packets.
181 */
182 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC
183 || !on)
184 return;
185 get_rdisc_sock();
186 }
187
188 if (!(ifp->int_if_flags & IFF_MULTICAST)) {
189 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS);
190 return;
191 }
192
193 #ifdef MCAST_PPP_BUG
194 if (ifp->int_if_flags & IFF_POINTOPOINT)
195 return;
196 #endif
197 memset(&m, 0, sizeof(m));
198 #ifdef MCAST_IFINDEX
199 m.imr_interface.s_addr = htonl(ifp->int_index);
200 #else
201 m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT)
202 ? ifp->int_dstaddr
203 : ifp->int_addr);
204 #endif
205 if (supplier
206 || (ifp->int_state & IS_NO_ADV_IN)
207 || !on) {
208 /* stop listening to advertisements
209 */
210 if (ifp->int_state & IS_ALL_HOSTS) {
211 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
212 if (setsockopt(rdisc_sock, IPPROTO_IP,
213 IP_DROP_MEMBERSHIP,
214 &m, sizeof(m)) < 0)
215 LOGERR("IP_DROP_MEMBERSHIP ALLHOSTS");
216 ifp->int_state &= ~IS_ALL_HOSTS;
217 }
218
219 } else if (!(ifp->int_state & IS_ALL_HOSTS)) {
220 /* start listening to advertisements
221 */
222 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
223 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
224 &m, sizeof(m)) < 0) {
225 LOGERR("IP_ADD_MEMBERSHIP ALLHOSTS");
226 } else {
227 ifp->int_state |= IS_ALL_HOSTS;
228 }
229 }
230
231 if (!supplier
232 || (ifp->int_state & IS_NO_ADV_OUT)
233 || !on) {
234 /* stop listening to solicitations
235 */
236 if (ifp->int_state & IS_ALL_ROUTERS) {
237 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP);
238 if (setsockopt(rdisc_sock, IPPROTO_IP,
239 IP_DROP_MEMBERSHIP,
240 &m, sizeof(m)) < 0)
241 LOGERR("IP_DROP_MEMBERSHIP ALLROUTERS");
242 ifp->int_state &= ~IS_ALL_ROUTERS;
243 }
244
245 } else if (!(ifp->int_state & IS_ALL_ROUTERS)) {
246 /* start hearing solicitations
247 */
248 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP);
249 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
250 &m, sizeof(m)) < 0) {
251 LOGERR("IP_ADD_MEMBERSHIP ALLROUTERS");
252 } else {
253 ifp->int_state |= IS_ALL_ROUTERS;
254 }
255 }
256 }
257
258
259 /* start supplying routes
260 */
261 void
set_supplier(void)262 set_supplier(void)
263 {
264 struct interface *ifp;
265 struct dr *drp;
266
267 if (supplier_set)
268 return;
269
270 trace_act("start supplying routes");
271
272 /* Forget discovered routes.
273 */
274 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
275 drp->dr_recv_pref = 0;
276 drp->dr_life = 0;
277 }
278 rdisc_age(0);
279
280 supplier_set = 1;
281 supplier = 1;
282
283 /* Do not start advertising until we have heard some RIP routes */
284 LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME);
285
286 /* Switch router discovery multicast groups from soliciting
287 * to advertising.
288 */
289 for (ifp = ifnet; ifp; ifp = ifp->int_next) {
290 if (ifp->int_state & IS_BROKE)
291 continue;
292 ifp->int_rdisc_cnt = 0;
293 ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec;
294 ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME;
295 set_rdisc_mg(ifp, 1);
296 }
297
298 /* get rid of any redirects */
299 del_redirects(0,0);
300 }
301
302
303 /* age discovered routes and find the best one
304 */
305 void
rdisc_age(naddr bad_gate)306 rdisc_age(naddr bad_gate)
307 {
308 time_t sec;
309 struct dr *drp;
310
311
312 /* If only advertising, then do only that. */
313 if (supplier) {
314 /* If switching from client to server, get rid of old
315 * default routes.
316 */
317 if (cur_drp != 0)
318 rdisc_sort();
319 rdisc_adv();
320 return;
321 }
322
323 /* If we are being told about a bad router,
324 * then age the discovered default route, and if there is
325 * no alternative, solicit a replacement.
326 */
327 if (bad_gate != 0) {
328 /* Look for the bad discovered default route.
329 * Age it and note its interface.
330 */
331 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
332 if (drp->dr_ts == 0)
333 continue;
334
335 /* When we find the bad router, then age the route
336 * to at most SUPPLY_INTERVAL.
337 * This is contrary to RFC 1256, but defends against
338 * black holes.
339 */
340 if (drp->dr_gate == bad_gate) {
341 sec = (now.tv_sec - drp->dr_life
342 + SUPPLY_INTERVAL);
343 if (drp->dr_ts > sec) {
344 trace_act("age 0.0.0.0 --> %s via %s",
345 naddr_ntoa(drp->dr_gate),
346 drp->dr_ifp->int_name);
347 drp->dr_ts = sec;
348 }
349 break;
350 }
351 }
352 }
353
354 rdisc_sol();
355 rdisc_sort();
356
357 /* Delete old redirected routes to keep the kernel table small,
358 * and to prevent black holes. Check that the kernel table
359 * matches the daemon table (i.e. has the default route).
360 * But only if RIP is not running and we are not dealing with
361 * a bad gateway, since otherwise age() will be called.
362 */
363 if (rip_sock < 0 && bad_gate == 0)
364 age(0);
365 }
366
367
368 /* Zap all routes discovered via an interface that has gone bad
369 * This should only be called when !(ifp->int_state & IS_ALIAS)
370 */
371 void
if_bad_rdisc(struct interface * ifp)372 if_bad_rdisc(struct interface *ifp)
373 {
374 struct dr *drp;
375
376 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
377 if (drp->dr_ifp != ifp)
378 continue;
379 drp->dr_recv_pref = 0;
380 drp->dr_ts = 0;
381 drp->dr_life = 0;
382 }
383
384 /* make a note to re-solicit, turn RIP on or off, etc. */
385 rdisc_timer.tv_sec = 0;
386 }
387
388
389 /* mark an interface ok for router discovering.
390 */
391 void
if_ok_rdisc(struct interface * ifp)392 if_ok_rdisc(struct interface *ifp)
393 {
394 set_rdisc_mg(ifp, 1);
395
396 ifp->int_rdisc_cnt = 0;
397 ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier
398 ? MIN_WAITTIME
399 : MAX_SOLICITATION_DELAY);
400 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
401 rdisc_timer = ifp->int_rdisc_timer;
402 }
403
404
405 /* get rid of a dead discovered router
406 */
407 static void
del_rdisc(struct dr * drp)408 del_rdisc(struct dr *drp)
409 {
410 struct interface *ifp;
411 naddr gate;
412 int i;
413
414
415 del_redirects(gate = drp->dr_gate, 0);
416 drp->dr_ts = 0;
417 drp->dr_life = 0;
418
419
420 /* Count the other discovered routes on the interface.
421 */
422 i = 0;
423 ifp = drp->dr_ifp;
424 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
425 if (drp->dr_ts != 0
426 && drp->dr_ifp == ifp)
427 i++;
428 }
429
430 /* If that was the last good discovered router on the interface,
431 * then solicit a new one.
432 * This is contrary to RFC 1256, but defends against black holes.
433 */
434 if (i != 0) {
435 trace_act("discovered router %s via %s"
436 " is bad--have %d remaining",
437 naddr_ntoa(gate), ifp->int_name, i);
438 } else if (ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) {
439 trace_act("last discovered router %s via %s"
440 " is bad--re-solicit",
441 naddr_ntoa(gate), ifp->int_name);
442 ifp->int_rdisc_cnt = 0;
443 ifp->int_rdisc_timer.tv_sec = 0;
444 rdisc_sol();
445 } else {
446 trace_act("last discovered router %s via %s"
447 " is bad--wait to solicit",
448 naddr_ntoa(gate), ifp->int_name);
449 }
450 }
451
452
453 /* Find the best discovered route,
454 * and discard stale routers.
455 */
456 static void
rdisc_sort(void)457 rdisc_sort(void)
458 {
459 struct dr *drp, *new_drp;
460 struct rt_entry *rt;
461 struct rt_spare new;
462 struct interface *ifp;
463 u_int new_st = 0;
464 n_long new_pref = 0;
465
466
467 /* Find the best discovered route.
468 */
469 new_drp = 0;
470 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
471 if (drp->dr_ts == 0)
472 continue;
473 ifp = drp->dr_ifp;
474
475 /* Get rid of expired discovered routers.
476 */
477 if (drp->dr_ts + drp->dr_life <= now.tv_sec) {
478 del_rdisc(drp);
479 continue;
480 }
481
482 LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1);
483
484 /* Update preference with possibly changed interface
485 * metric.
486 */
487 drp->dr_pref = PREF(drp->dr_recv_pref, ifp);
488
489 /* Prefer the current route to prevent thrashing.
490 * Prefer shorter lifetimes to speed the detection of
491 * bad routers.
492 * Avoid sick interfaces.
493 */
494 if (new_drp == 0
495 || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK)
496 && (new_pref < drp->dr_pref
497 || (new_pref == drp->dr_pref
498 && (drp == cur_drp
499 || (new_drp != cur_drp
500 && new_drp->dr_life > drp->dr_life)))))
501 || ((new_st & IS_SICK)
502 && !(drp->dr_ifp->int_state & IS_SICK))) {
503 new_drp = drp;
504 new_st = drp->dr_ifp->int_state;
505 new_pref = drp->dr_pref;
506 }
507 }
508
509 /* switch to a better default route
510 */
511 if (new_drp != cur_drp) {
512 rt = rtget(RIP_DEFAULT, 0);
513
514 /* Stop using discovered routes if they are all bad
515 */
516 if (new_drp == 0) {
517 trace_act("turn off Router Discovery client");
518 rdisc_ok = 0;
519
520 if (rt != 0
521 && (rt->rt_state & RS_RDISC)) {
522 new = rt->rt_spares[0];
523 new.rts_metric = HOPCNT_INFINITY;
524 new.rts_time = now.tv_sec - GARBAGE_TIME;
525 rtchange(rt, rt->rt_state & ~RS_RDISC,
526 &new, 0);
527 rtswitch(rt, 0);
528 }
529
530 } else {
531 if (cur_drp == 0) {
532 trace_act("turn on Router Discovery client"
533 " using %s via %s",
534 naddr_ntoa(new_drp->dr_gate),
535 new_drp->dr_ifp->int_name);
536 rdisc_ok = 1;
537
538 } else {
539 trace_act("switch Router Discovery from"
540 " %s via %s to %s via %s",
541 naddr_ntoa(cur_drp->dr_gate),
542 cur_drp->dr_ifp->int_name,
543 naddr_ntoa(new_drp->dr_gate),
544 new_drp->dr_ifp->int_name);
545 }
546
547 memset(&new, 0, sizeof(new));
548 new.rts_ifp = new_drp->dr_ifp;
549 new.rts_gate = new_drp->dr_gate;
550 new.rts_router = new_drp->dr_gate;
551 new.rts_metric = HOPCNT_INFINITY-1;
552 new.rts_time = now.tv_sec;
553 if (rt != 0) {
554 rtchange(rt, rt->rt_state | RS_RDISC, &new, 0);
555 } else {
556 rtadd(RIP_DEFAULT, 0, RS_RDISC, &new);
557 }
558 }
559
560 cur_drp = new_drp;
561 }
562
563 /* turn RIP on or off */
564 if (!rdisc_ok || rip_interfaces > 1) {
565 rip_on(0);
566 } else {
567 rip_off();
568 }
569 }
570
571
572 /* handle a single address in an advertisement
573 */
574 static void
parse_ad(naddr from,naddr gate,n_long pref,u_short life,struct interface * ifp)575 parse_ad(naddr from,
576 naddr gate,
577 n_long pref, /* signed and in network order */
578 u_short life, /* in host byte order */
579 struct interface *ifp)
580 {
581 static struct msg_limit bad_gate;
582 struct dr *drp, *new_drp;
583
584
585 if (gate == RIP_DEFAULT
586 || !check_dst(gate)) {
587 msglim(&bad_gate, from,"router %s advertising bad gateway %s",
588 naddr_ntoa(from),
589 naddr_ntoa(gate));
590 return;
591 }
592
593 /* ignore pointers to ourself and routes via unreachable networks
594 */
595 if (ifwithaddr(gate, 1, 0) != 0) {
596 trace_pkt(" discard Router Discovery Ad pointing at us");
597 return;
598 }
599 if (!on_net(gate, ifp->int_net, ifp->int_mask)) {
600 trace_pkt(" discard Router Discovery Ad"
601 " toward unreachable net");
602 return;
603 }
604
605 /* Convert preference to an unsigned value
606 * and later bias it by the metric of the interface.
607 */
608 pref = UNSIGN_PREF(ntohl(pref));
609
610 if (pref == 0 || life < MinMaxAdvertiseInterval) {
611 pref = 0;
612 life = 0;
613 }
614
615 for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) {
616 /* accept new info for a familiar entry
617 */
618 if (drp->dr_gate == gate) {
619 new_drp = drp;
620 break;
621 }
622
623 if (life == 0)
624 continue; /* do not worry about dead ads */
625
626 if (drp->dr_ts == 0) {
627 new_drp = drp; /* use unused entry */
628
629 } else if (new_drp == 0) {
630 /* look for an entry worse than the new one to
631 * reuse.
632 */
633 if ((!(ifp->int_state & IS_SICK)
634 && (drp->dr_ifp->int_state & IS_SICK))
635 || (pref > drp->dr_pref
636 && !((ifp->int_state ^ drp->dr_ifp->int_state)
637 & IS_SICK)))
638 new_drp = drp;
639
640 } else if (new_drp->dr_ts != 0) {
641 /* look for the least valuable entry to reuse
642 */
643 if ((!(new_drp->dr_ifp->int_state & IS_SICK)
644 && (drp->dr_ifp->int_state & IS_SICK))
645 || (new_drp->dr_pref > drp->dr_pref
646 && !((new_drp->dr_ifp->int_state
647 ^ drp->dr_ifp->int_state)
648 & IS_SICK)))
649 new_drp = drp;
650 }
651 }
652
653 /* forget it if all of the current entries are better */
654 if (new_drp == 0)
655 return;
656
657 new_drp->dr_ifp = ifp;
658 new_drp->dr_gate = gate;
659 new_drp->dr_ts = now.tv_sec;
660 new_drp->dr_life = life;
661 new_drp->dr_recv_pref = pref;
662 /* bias functional preference by metric of the interface */
663 new_drp->dr_pref = PREF(pref,ifp);
664
665 /* after hearing a good advertisement, stop asking
666 */
667 if (!(ifp->int_state & IS_SICK))
668 ifp->int_rdisc_cnt = MAX_SOLICITATIONS;
669 }
670
671
672 /* Compute the IP checksum
673 * This assumes the packet is less than 32K long.
674 */
675 static u_short
in_cksum(u_short * p,u_int len)676 in_cksum(u_short *p,
677 u_int len)
678 {
679 u_int sum = 0;
680 int nwords = len >> 1;
681
682 while (nwords-- != 0)
683 sum += *p++;
684
685 if (len & 1)
686 sum += *(u_char *)p;
687
688 /* end-around-carry */
689 sum = (sum >> 16) + (sum & 0xffff);
690 sum += (sum >> 16);
691 return (~sum);
692 }
693
694
695 /* Send a router discovery advertisement or solicitation ICMP packet.
696 */
697 static void
send_rdisc(union ad_u * p,int p_size,struct interface * ifp,naddr dst,int type)698 send_rdisc(union ad_u *p,
699 int p_size,
700 struct interface *ifp,
701 naddr dst, /* 0 or unicast destination */
702 int type) /* 0=unicast, 1=bcast, 2=mcast */
703 {
704 struct sockaddr_in rsin;
705 int flags;
706 const char *msg;
707 naddr tgt_mcast;
708
709
710 memset(&rsin, 0, sizeof(rsin));
711 rsin.sin_addr.s_addr = dst;
712 rsin.sin_family = AF_INET;
713 #ifdef _HAVE_SIN_LEN
714 rsin.sin_len = sizeof(rsin);
715 #endif
716 flags = MSG_DONTROUTE;
717
718 switch (type) {
719 case 0: /* unicast */
720 default:
721 msg = "Send";
722 break;
723
724 case 1: /* broadcast */
725 if (ifp->int_if_flags & IFF_POINTOPOINT) {
726 msg = "Send pt-to-pt";
727 rsin.sin_addr.s_addr = ifp->int_dstaddr;
728 } else {
729 msg = "Send broadcast";
730 rsin.sin_addr.s_addr = ifp->int_brdaddr;
731 }
732 break;
733
734 case 2: /* multicast */
735 msg = "Send multicast";
736 if (ifp->int_state & IS_DUP) {
737 trace_act("abort multicast output via %s"
738 " with duplicate address",
739 ifp->int_name);
740 return;
741 }
742 if (rdisc_sock_mcast != ifp) {
743 /* select the right interface. */
744 #ifdef MCAST_IFINDEX
745 /* specify ifindex */
746 tgt_mcast = htonl(ifp->int_index);
747 #else
748 #ifdef MCAST_PPP_BUG
749 /* Do not specify the primary interface explicitly
750 * if we have the multicast point-to-point kernel
751 * bug, since the kernel will do the wrong thing
752 * if the local address of a point-to-point link
753 * is the same as the address of an ordinary
754 * interface.
755 */
756 if (ifp->int_addr == myaddr) {
757 tgt_mcast = 0;
758 } else
759 #endif
760 tgt_mcast = ifp->int_addr;
761 #endif
762 if (0 > setsockopt(rdisc_sock,
763 IPPROTO_IP, IP_MULTICAST_IF,
764 &tgt_mcast, sizeof(tgt_mcast))) {
765 LOGERR("setsockopt(rdisc_sock,"
766 "IP_MULTICAST_IF)");
767 rdisc_sock_mcast = 0;
768 return;
769 }
770 rdisc_sock_mcast = ifp;
771 }
772 flags = 0;
773 break;
774 }
775
776 if (rdisc_sock < 0)
777 get_rdisc_sock();
778
779 trace_rdisc(msg, ifp ? ifp->int_addr : 0, rsin.sin_addr.s_addr, ifp,
780 p, p_size);
781
782 if (0 > sendto(rdisc_sock, p, p_size, flags,
783 (struct sockaddr *)&rsin, sizeof(rsin))) {
784 if (ifp == 0 || !(ifp->int_state & IS_BROKE))
785 msglog("sendto(%s%s%s): %s",
786 ifp != 0 ? ifp->int_name : "",
787 ifp != 0 ? ", " : "",
788 inet_ntoa(rsin.sin_addr),
789 strerror(errno));
790 if (ifp != 0)
791 if_sick(ifp);
792 }
793 }
794
795
796 /* Send an advertisement
797 */
798 static void
send_adv(struct interface * ifp,naddr dst,int type)799 send_adv(struct interface *ifp,
800 naddr dst, /* 0 or unicast destination */
801 int type) /* 0=unicast, 1=bcast, 2=mcast */
802 {
803 union ad_u u;
804 n_long pref;
805
806
807 memset(&u, 0, sizeof(u.ad));
808
809 u.ad.icmp_type = ICMP_ROUTERADVERT;
810 u.ad.icmp_ad_num = 1;
811 u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4;
812
813 u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3);
814
815 /* Convert the configured preference to an unsigned value,
816 * bias it by the interface metric, and then send it as a
817 * signed, network byte order value.
818 */
819 pref = UNSIGN_PREF(ifp->int_rdisc_pref);
820 u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp)));
821
822 u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr;
823
824 u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad));
825
826 send_rdisc(&u, sizeof(u.ad), ifp, dst, type);
827 }
828
829
830 /* Advertise for Router Discovery
831 */
832 void
rdisc_adv(void)833 rdisc_adv(void)
834 {
835 struct interface *ifp;
836
837 if (!supplier)
838 return;
839
840 rdisc_timer.tv_sec = now.tv_sec + NEVER;
841
842 for (ifp = ifnet; ifp; ifp = ifp->int_next) {
843 if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE)))
844 continue;
845
846 if (!timercmp(&ifp->int_rdisc_timer, &now, >)
847 || stopint) {
848 send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP),
849 (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2);
850 ifp->int_rdisc_cnt++;
851
852 intvl_random(&ifp->int_rdisc_timer,
853 (ifp->int_rdisc_int*3)/4,
854 ifp->int_rdisc_int);
855 if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS
856 && (ifp->int_rdisc_timer.tv_sec
857 > MAX_INITIAL_ADVERT_INTERVAL)) {
858 ifp->int_rdisc_timer.tv_sec
859 = MAX_INITIAL_ADVERT_INTERVAL;
860 }
861 timevaladd(&ifp->int_rdisc_timer, &now);
862 }
863
864 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
865 rdisc_timer = ifp->int_rdisc_timer;
866 }
867 }
868
869
870 /* Solicit for Router Discovery
871 */
872 void
rdisc_sol(void)873 rdisc_sol(void)
874 {
875 struct interface *ifp;
876 union ad_u u;
877
878
879 if (supplier)
880 return;
881
882 rdisc_timer.tv_sec = now.tv_sec + NEVER;
883
884 for (ifp = ifnet; ifp; ifp = ifp->int_next) {
885 if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE))
886 || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
887 continue;
888
889 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) {
890 memset(&u, 0, sizeof(u.so));
891 u.so.icmp_type = ICMP_ROUTERSOLICIT;
892 u.so.icmp_cksum = in_cksum((u_short*)&u.so,
893 sizeof(u.so));
894 send_rdisc(&u, sizeof(u.so), ifp,
895 htonl(INADDR_ALLROUTERS_GROUP),
896 ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2));
897
898 if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
899 continue;
900
901 ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL;
902 ifp->int_rdisc_timer.tv_usec = 0;
903 timevaladd(&ifp->int_rdisc_timer, &now);
904 }
905
906 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
907 rdisc_timer = ifp->int_rdisc_timer;
908 }
909 }
910
911
912 /* check the IP header of a possible Router Discovery ICMP packet */
913 static struct interface * /* 0 if bad */
ck_icmp(const char * act,naddr from,struct interface * ifp,naddr to,union ad_u * p,u_int len)914 ck_icmp(const char *act,
915 naddr from,
916 struct interface *ifp,
917 naddr to,
918 union ad_u *p,
919 u_int len)
920 {
921 const char *type;
922
923
924 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
925 type = "advertisement";
926 } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) {
927 type = "solicitation";
928 } else {
929 return 0;
930 }
931
932 if (p->icmp.icmp_code != 0) {
933 trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s",
934 type, p->icmp.icmp_code,
935 naddr_ntoa(from), naddr_ntoa(to));
936 return 0;
937 }
938
939 trace_rdisc(act, from, to, ifp, p, len);
940
941 if (ifp == 0)
942 trace_pkt("unknown interface for router-discovery %s"
943 " from %s to %s",
944 type, naddr_ntoa(from), naddr_ntoa(to));
945
946 return ifp;
947 }
948
949
950 /* read packets from the router discovery socket
951 */
952 void
read_d(void)953 read_d(void)
954 {
955 static struct msg_limit bad_asize, bad_len;
956 #ifdef USE_PASSIFNAME
957 static struct msg_limit bad_name;
958 #endif
959 struct sockaddr_in from;
960 socklen_t fromlen;
961 int n, cc, hlen;
962 struct {
963 #ifdef USE_PASSIFNAME
964 char ifname[IFNAMSIZ];
965 #endif
966 union {
967 struct ip ip;
968 u_short s[512/2];
969 u_char b[512];
970 } pkt;
971 } buf;
972 union ad_u *p;
973 n_long *wp;
974 struct interface *ifp;
975
976
977 for (;;) {
978 fromlen = sizeof(from);
979 cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0,
980 (struct sockaddr*)&from,
981 &fromlen);
982 if (cc <= 0) {
983 if (cc < 0 && errno != EWOULDBLOCK)
984 LOGERR("recvfrom(rdisc_sock)");
985 break;
986 }
987 if (fromlen != sizeof(struct sockaddr_in))
988 logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d",
989 fromlen);
990 #ifdef USE_PASSIFNAME
991 if ((cc -= sizeof(buf.ifname)) < 0)
992 logbad(0,"missing USE_PASSIFNAME; only %d bytes",
993 cc+sizeof(buf.ifname));
994 #endif
995
996 hlen = buf.pkt.ip.ip_hl << 2;
997 if (cc < hlen + ICMP_MINLEN)
998 continue;
999 p = (union ad_u *)&buf.pkt.b[hlen];
1000 cc -= hlen;
1001
1002 #ifdef USE_PASSIFNAME
1003 ifp = ifwithname(buf.ifname, 0);
1004 if (ifp == 0)
1005 msglim(&bad_name, from.sin_addr.s_addr,
1006 "impossible rdisc if_ name %.*s",
1007 IFNAMSIZ, buf.ifname);
1008 #else
1009 /* If we could tell the interface on which a packet from
1010 * address 0 arrived, we could deal with such solicitations.
1011 */
1012 ifp = ((from.sin_addr.s_addr == 0)
1013 ? 0 : iflookup(from.sin_addr.s_addr));
1014 #endif
1015 ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp,
1016 buf.pkt.ip.ip_dst.s_addr, p, cc);
1017 if (ifp == 0)
1018 continue;
1019 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) {
1020 trace_pkt(" "
1021 "discard our own Router Discovery message");
1022 continue;
1023 }
1024
1025 switch (p->icmp.icmp_type) {
1026 case ICMP_ROUTERADVERT:
1027 if (p->ad.icmp_ad_asize*4
1028 < (int)sizeof(p->ad.icmp_ad_info[0])) {
1029 msglim(&bad_asize, from.sin_addr.s_addr,
1030 "intolerable rdisc address size=%d",
1031 p->ad.icmp_ad_asize);
1032 continue;
1033 }
1034 if (p->ad.icmp_ad_num == 0) {
1035 trace_pkt(" empty?");
1036 continue;
1037 }
1038 if (cc != (int)(sizeof(p->ad)
1039 - sizeof(p->ad.icmp_ad_info)
1040 + (p->ad.icmp_ad_num
1041 * sizeof(p->ad.icmp_ad_info[0])))) {
1042 msglim(&bad_len, from.sin_addr.s_addr,
1043 "rdisc length %d does not match ad_num"
1044 " %d", cc, p->ad.icmp_ad_num);
1045 continue;
1046 }
1047 if (supplier)
1048 continue;
1049 if (ifp->int_state & IS_NO_ADV_IN)
1050 continue;
1051
1052 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
1053 for (n = 0; n < p->ad.icmp_ad_num; n++) {
1054 parse_ad(from.sin_addr.s_addr,
1055 wp[0], wp[1],
1056 ntohs(p->ad.icmp_ad_life),
1057 ifp);
1058 wp += p->ad.icmp_ad_asize;
1059 }
1060 break;
1061
1062
1063 case ICMP_ROUTERSOLICIT:
1064 if (!supplier)
1065 continue;
1066 if (ifp->int_state & IS_NO_ADV_OUT)
1067 continue;
1068 if (stopint)
1069 continue;
1070
1071 /* XXX
1072 * We should handle messages from address 0.
1073 */
1074
1075 /* Respond with a point-to-point advertisement */
1076 send_adv(ifp, from.sin_addr.s_addr, 0);
1077 break;
1078 }
1079 }
1080
1081 rdisc_sort();
1082 }
1083