xref: /netbsd-src/usr.sbin/mrouted/vif.c (revision ae9172d6cd9432a6a1a56760d86b32c57a66c39c)
1 /*
2  * The mrouted program is covered by the license in the accompanying file
3  * named "LICENSE".  Use of the mrouted program represents acceptance of
4  * the terms and conditions listed in that file.
5  *
6  * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
7  * Leland Stanford Junior University.
8  *
9  *
10  * from: Id: vif.c,v 1.5 1993/06/24 05:11:16 deering Exp
11  *      $Id: vif.c,v 1.3 1994/06/09 16:04:03 brezak Exp $
12  */
13 
14 #ifndef lint
15 static char rcsid[] = "$Id: vif.c,v 1.3 1994/06/09 16:04:03 brezak Exp $";
16 #endif
17 
18 #include "defs.h"
19 
20 
21 /*
22  * Exported variables.
23  */
24 struct uvif	uvifs[MAXVIFS];	/* array of virtual interfaces */
25 vifi_t		numvifs;	/* number of vifs in use       */
26 int		vifs_down;	/* 1=>some interfaces are down */
27 int		udp_socket;	/* Since the honkin' kernel doesn't support */
28 				/* ioctls on raw IP sockets, we need a UDP  */
29 				/* socket as well as our IGMP (raw) socket. */
30 				/* How dumb.                                */
31 
32 /*
33  * Forward declarations.
34  */
35 static void start_vif();
36 static void stop_vif();
37 
38 
39 /*
40  * Initialize the virtual interfaces.
41  */
42 void init_vifs()
43 {
44     vifi_t vifi;
45     struct uvif *v;
46     int enabled_vifs, enabled_phyints;
47 
48     numvifs = 0;
49     vifs_down = FALSE;
50 
51     /*
52      * Configure the vifs based on the interface configuration of the
53      * the kernel and the contents of the configuration file.
54      * (Open a UDP socket for ioctl use in the config procedures.)
55      */
56     if ((udp_socket = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
57 	log(LOG_ERR, errno, "UDP socket");
58     config_vifs_from_kernel();
59     config_vifs_from_file();
60 
61     /*
62      * Quit if there are fewer than two enabled vifs.
63      */
64     enabled_vifs    = 0;
65     enabled_phyints = 0;
66     for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
67 	if (!(v->uv_flags & VIFF_DISABLED)) {
68 	    ++enabled_vifs;
69 	    if (!(v->uv_flags & VIFF_TUNNEL))
70 		++enabled_phyints;
71 	}
72     }
73     if (enabled_vifs < 2)
74 	log(LOG_ERR, 0, "can't forward: %s",
75 	    enabled_vifs == 0 ? "no enabled vifs" : "only one enabled vif");
76 
77     if (enabled_phyints == 0)
78 	log(LOG_WARNING, 0,
79 	    "no enabled interfaces, forwarding via tunnels only");
80 
81     /*
82      * Start routing on all virtual interfaces that are not down or
83      * administratively disabled.
84      */
85     for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
86 	if (!(v->uv_flags & VIFF_DISABLED)) {
87 	    if (!(v->uv_flags & VIFF_DOWN))
88 		start_vif(vifi);
89 	    else log(LOG_INFO, 0,
90 		    "%s is not yet up; vif #%u not in service",
91 		    v->uv_name, vifi);
92 	}
93     }
94 }
95 
96 
97 /*
98  * See if any interfaces have changed from up state to down, or vice versa,
99  * including any non-multicast-capable interfaces that are in use as local
100  * tunnel end-points.  Ignore interfaces that have been administratively
101  * disabled.
102  */
103 void check_vif_state()
104 {
105     register vifi_t vifi;
106     register struct uvif *v;
107     struct ifreq ifr;
108 
109     vifs_down = FALSE;
110     for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
111 
112 	if (v->uv_flags & VIFF_DISABLED) continue;
113 
114 	strncpy(ifr.ifr_name, v->uv_name, IFNAMSIZ);
115 	if (ioctl(udp_socket, SIOCGIFFLAGS, (char *)&ifr) < 0)
116 	    log(LOG_ERR, errno,
117 		"ioctl SIOCGIFFLAGS for %s", ifr.ifr_name);
118 
119 	if (v->uv_flags & VIFF_DOWN) {
120 	    if (ifr.ifr_flags & IFF_UP) {
121 		v->uv_flags &= ~VIFF_DOWN;
122 		start_vif(vifi);
123 		log(LOG_INFO, 0,
124 		    "%s has come up; vif #%u now in service",
125 		    v->uv_name, vifi);
126 	    }
127 	    else vifs_down = TRUE;
128 	}
129 	else {
130 	    if (!(ifr.ifr_flags & IFF_UP)) {
131 		stop_vif(vifi);
132 		v->uv_flags |= VIFF_DOWN;
133 		log(LOG_INFO, 0,
134 		    "%s has gone down; vif #%u taken out of service",
135 		    v->uv_name, vifi);
136 		vifs_down = TRUE;
137 	    }
138 	}
139     }
140 }
141 
142 
143 /*
144  * Start routing on the specified virtual interface.
145  */
146 static void start_vif(vifi)
147     vifi_t vifi;
148 {
149     struct uvif *v;
150     u_long src, dst;
151 
152     v   = &uvifs[vifi];
153     src = v->uv_lcl_addr;
154     dst = (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr : dvmrp_group;
155 
156     /*
157      * Install the interface in the kernel's vif structure.
158      */
159     k_add_vif(vifi, &uvifs[vifi]);
160 
161     /*
162      * Update the existing route entries to take into account the new vif.
163      */
164     add_vif_to_routes(vifi);
165 
166     if (!(v->uv_flags & VIFF_TUNNEL)) {
167 	/*
168 	 * Join the DVMRP multicast group on the interface.
169 	 * (This is not strictly necessary, since the kernel promiscuously
170 	 * receives IGMP packets addressed to ANY IP multicast group while
171 	 * multicast routing is enabled.  However, joining the group allows
172 	 * this host to receive non-IGMP packets as well, such as 'pings'.)
173 	 */
174 	k_join(dvmrp_group, src);
175 
176 	/*
177 	 * Install an entry in the routing table for the subnet to which
178 	 * the interface is connected.
179 	 */
180 	start_route_updates();
181 	update_route(v->uv_subnet, v->uv_subnetmask, 0, 0, vifi);
182 
183 	/*
184 	 * Until neighbors are discovered, assume responsibility for sending
185 	 * periodic group membership queries to the subnet.  Send the first
186 	 * query.
187 	 */
188 	v->uv_flags |= VIFF_QUERIER;
189 	send_igmp(src, allhosts_group, IGMP_HOST_MEMBERSHIP_QUERY, 0, 0, 0);
190     }
191 
192     /*
193      * Send a probe via the new vif to look for neighbors.
194      */
195     send_igmp(src, dst, IGMP_DVMRP, DVMRP_PROBE, htonl(MROUTED_LEVEL), 0);
196 }
197 
198 
199 /*
200  * Stop routing on the specified virtual interface.
201  */
202 static void stop_vif(vifi)
203     vifi_t vifi;
204 {
205     struct uvif *v;
206     struct listaddr *a;
207 
208     v = &uvifs[vifi];
209 
210     if (!(v->uv_flags & VIFF_TUNNEL)) {
211 	/*
212 	 * Depart from the DVMRP multicast group on the interface.
213 	 */
214 	k_leave(dvmrp_group, v->uv_lcl_addr);
215 
216 	/*
217 	 * Update the entry in the routing table for the subnet to which
218 	 * the interface is connected, to take into account the interface
219 	 * failure.
220 	 */
221 	start_route_updates();
222 	update_route(v->uv_subnet, v->uv_subnetmask, UNREACHABLE, 0, vifi);
223 
224 	/*
225 	 * Discard all group addresses.  (No need to tell kernel;
226 	 * the k_del_vif() call, below, will clean up kernel state.)
227 	 */
228 	while (v->uv_groups != NULL) {
229 	    a = v->uv_groups;
230 	    v->uv_groups = a->al_next;
231 	    free((char *)a);
232 	}
233 
234 	v->uv_flags &= ~VIFF_QUERIER;
235     }
236 
237     /*
238      * Update the existing route entries to take into account the vif failure.
239      */
240     delete_vif_from_routes(vifi);
241 
242     /*
243      * Delete the interface from the kernel's vif structure.
244      */
245     k_del_vif(vifi);
246 
247     /*
248      * Discard all neighbor addresses.
249      */
250     while (v->uv_neighbors != NULL) {
251 	a = v->uv_neighbors;
252 	v->uv_neighbors = a->al_next;
253 	free((char *)a);
254     }
255 }
256 
257 
258 /*
259  * Find the virtual interface from which an incoming packet arrived,
260  * based on the packet's source and destination IP addresses.
261  */
262 vifi_t find_vif(src, dst)
263     register u_long src;
264     register u_long dst;
265 {
266     register vifi_t vifi;
267     register struct uvif *v;
268 
269     for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
270 	if (!(v->uv_flags & (VIFF_DOWN|VIFF_DISABLED))) {
271 	    if (v->uv_flags & VIFF_TUNNEL) {
272 		if (src == v->uv_rmt_addr && dst == v->uv_lcl_addr)
273 		    return(vifi);
274 	    }
275 	    else {
276 		if ((src & v->uv_subnetmask) == v->uv_subnet &&
277 		    src != v->uv_subnetbcast)
278 		    return(vifi);
279 	    }
280 	}
281     }
282     return (NO_VIF);
283 }
284 
285 
286 /*
287  * Send group membership queries to all subnets for which I am querier.
288  */
289 void query_groups()
290 {
291     register vifi_t vifi;
292     register struct uvif *v;
293 
294     for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
295 	if (v->uv_flags & VIFF_QUERIER) {
296 	    send_igmp(v->uv_lcl_addr, allhosts_group,
297 		      IGMP_HOST_MEMBERSHIP_QUERY, 0, 0, 0);
298 	}
299     }
300 }
301 
302 
303 /*
304  * Process an incoming group membership report.
305  */
306 void accept_group_report(src, dst, group)
307     u_long src, dst, group;
308 {
309     register vifi_t vifi;
310     register struct uvif *v;
311     register struct listaddr *g;
312 
313     if ((vifi = find_vif(src, dst)) == NO_VIF ||
314 	(uvifs[vifi].uv_flags & VIFF_TUNNEL)) {
315 	log(LOG_INFO, 0,
316 	    "ignoring group membership report from non-adjacent host %s",
317 	    inet_fmt(src, s1));
318 	return;
319     }
320 
321     v = &uvifs[vifi];
322 
323     /*
324      * Look for the group in our group list; if found, reset its timer.
325      */
326     for (g = v->uv_groups; g != NULL; g = g->al_next) {
327 	if (group == g->al_addr) {
328 	    g->al_timer = 0;
329 	    break;
330 	}
331     }
332 
333     /*
334      * If not found, add it to the list and tell the kernel.
335      */
336     if (g == NULL) {
337 	g = (struct listaddr *)malloc(sizeof(struct listaddr));
338 	if (g == NULL)
339 	    log(LOG_ERR, 0, "ran out of memory");    /* fatal */
340 
341 	g->al_addr   = group;
342 	g->al_timer  = 0;
343 	g->al_next   = v->uv_groups;
344 	v->uv_groups = g;
345 
346 	k_add_group(vifi, group);
347     }
348 }
349 
350 
351 /*
352  * Send a probe on all vifs from which no neighbors have been heard recently.
353  */
354 void probe_for_neighbors()
355 {
356     register vifi_t vifi;
357     register struct uvif *v;
358 
359     for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
360 	if (!(v->uv_flags & (VIFF_DOWN|VIFF_DISABLED)) &&
361 	    v->uv_neighbors == NULL) {
362 	    send_igmp(v->uv_lcl_addr,
363 		      (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr
364 						  : dvmrp_group,
365 		      IGMP_DVMRP, DVMRP_PROBE, htonl(MROUTED_LEVEL), 0);
366 	}
367     }
368 }
369 
370 
371 /*
372  * Send a list of all of our neighbors to the requestor, `src'.
373  */
374 void accept_neighbor_request(src, dst)
375     u_long src, dst;
376 {
377     vifi_t vifi;
378     struct uvif *v;
379     u_char *p, *ncount;
380     struct listaddr *la;
381     int	datalen;
382     u_long temp_addr, us, them = src;
383 
384     /* Determine which of our addresses to use as the source of our response
385      * to this query.
386      */
387     if (IN_MULTICAST(ntohl(dst))) { /* query sent to a multicast group */
388 	int udp;		/* find best interface to reply on */
389 	struct sockaddr_in addr;
390 	int addrlen = sizeof(addr);
391 
392 	addr.sin_family = AF_INET;
393 	addr.sin_addr.s_addr = dst;
394 	addr.sin_port = htons(2000); /* any port over 1024 will do... */
395 	if ((udp = socket(AF_INET, SOCK_DGRAM, 0)) < 0
396 	    || connect(udp, (struct sockaddr *) &addr, sizeof(addr)) < 0
397 	    || getsockname(udp, (struct sockaddr *) &addr, &addrlen) < 0) {
398 	    log(LOG_WARNING, errno, "Determining local address");
399 	    close(udp);
400 	    return;
401 	}
402 	close(udp);
403 	us = addr.sin_addr.s_addr;
404     } else			/* query sent to us alone */
405 	us = dst;
406 
407 #define PUT_ADDR(a)	temp_addr = ntohl(a); \
408 			*p++ = temp_addr >> 24; \
409 			*p++ = (temp_addr >> 16) & 0xFF; \
410 			*p++ = (temp_addr >> 8) & 0xFF; \
411 			*p++ = temp_addr & 0xFF;
412 
413     p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
414     datalen = 0;
415 
416     for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
417 	if (v->uv_flags & VIFF_DISABLED)
418 	    continue;
419 
420 	ncount = 0;
421 
422 	for (la = v->uv_neighbors; la; la = la->al_next) {
423 
424 	    /* Make sure that there's room for this neighbor... */
425 	    if (datalen + (ncount == 0 ? 4 + 3 + 4 : 4) > MAX_DVMRP_DATA_LEN) {
426 		send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS,
427 			  htonl(MROUTED_LEVEL), datalen);
428 		p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
429 		datalen = 0;
430 		ncount = 0;
431 	    }
432 
433 	    /* Put out the header for this neighbor list... */
434 	    if (ncount == 0) {
435 		PUT_ADDR(v->uv_lcl_addr);
436 		*p++ = v->uv_metric;
437 		*p++ = v->uv_threshold;
438 		ncount = p;
439 		*p++ = 0;
440 		datalen += 4 + 3;
441 	    }
442 
443 	    PUT_ADDR(la->al_addr);
444 	    datalen += 4;
445 	    (*ncount)++;
446 	}
447     }
448 
449     if (datalen != 0)
450 	send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS, htonl(MROUTED_LEVEL),
451 		  datalen);
452 }
453 
454 /*
455  * Send a list of all of our neighbors to the requestor, `src'.
456  */
457 void accept_neighbor_request2(src, dst)
458     u_long src, dst;
459 {
460     vifi_t vifi;
461     struct uvif *v;
462     u_char *p, *ncount;
463     struct listaddr *la;
464     int	datalen;
465     u_long temp_addr, us, them = src;
466 
467     /* Determine which of our addresses to use as the source of our response
468      * to this query.
469      */
470     if (IN_MULTICAST(ntohl(dst))) { /* query sent to a multicast group */
471 	int udp;		/* find best interface to reply on */
472 	struct sockaddr_in addr;
473 	int addrlen = sizeof(addr);
474 
475 	addr.sin_family = AF_INET;
476 	addr.sin_addr.s_addr = dst;
477 	addr.sin_port = htons(2000); /* any port over 1024 will do... */
478 	if ((udp = socket(AF_INET, SOCK_DGRAM, 0)) < 0
479 	    || connect(udp, (struct sockaddr *) &addr, sizeof(addr)) < 0
480 	    || getsockname(udp, (struct sockaddr *) &addr, &addrlen) < 0) {
481 	    log(LOG_WARNING, errno, "Determining local address");
482 	    close(udp);
483 	    return;
484 	}
485 	close(udp);
486 	us = addr.sin_addr.s_addr;
487     } else			/* query sent to us alone */
488 	us = dst;
489 
490     p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
491     datalen = 0;
492 
493     for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
494 	register u_short vflags = v->uv_flags;
495 	register u_char rflags = 0;
496 	if (vflags & VIFF_TUNNEL)
497 	    rflags |= DVMRP_NF_TUNNEL;
498 	if (vflags & VIFF_SRCRT)
499 	    rflags |= DVMRP_NF_SRCRT;
500 	if (vflags & VIFF_DOWN)
501 	    rflags |= DVMRP_NF_DOWN;
502 	if (vflags & VIFF_DISABLED)
503 	    rflags |= DVMRP_NF_DISABLED;
504 	if (vflags & VIFF_QUERIER)
505 	    rflags |= DVMRP_NF_QUERIER;
506 	ncount = 0;
507 	la = v->uv_neighbors;
508 	if (la == NULL) {
509 		/*
510 		 * include down & disabled interfaces and interfaces on
511 		 * leaf nets.
512 		 */
513 		if (rflags & DVMRP_NF_TUNNEL)
514 		    rflags |= DVMRP_NF_DOWN;
515 		if (datalen > MAX_DVMRP_DATA_LEN - 12) {
516 		    send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2,
517 			      htonl(MROUTED_LEVEL), datalen);
518 		    p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
519 		    datalen = 0;
520 		}
521 		*(u_int*)p = v->uv_lcl_addr;
522 		p += 4;
523 		*p++ = v->uv_metric;
524 		*p++ = v->uv_threshold;
525 		*p++ = rflags;
526 		*p++ = 1;
527 		*(u_int*)p =  v->uv_rmt_addr;
528 		p += 4;
529 		datalen += 12;
530 	} else {
531 	    for ( ; la; la = la->al_next) {
532 		/* Make sure that there's room for this neighbor... */
533 		if (datalen + (ncount == 0 ? 4+4+4 : 4) > MAX_DVMRP_DATA_LEN) {
534 		    send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2,
535 			      htonl(MROUTED_LEVEL), datalen);
536 		    p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
537 		    datalen = 0;
538 		    ncount = 0;
539 		}
540 		/* Put out the header for this neighbor list... */
541 		if (ncount == 0) {
542 		    *(u_int*)p = v->uv_lcl_addr;
543 		    p += 4;
544 		    *p++ = v->uv_metric;
545 		    *p++ = v->uv_threshold;
546 		    *p++ = rflags;
547 		    ncount = p;
548 		    *p++ = 0;
549 		    datalen += 4 + 4;
550 		}
551 		*(u_int*)p = la->al_addr;
552 		p += 4;
553 		datalen += 4;
554 		(*ncount)++;
555 	    }
556 	}
557     }
558     if (datalen != 0)
559 	send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2, htonl(MROUTED_LEVEL),
560 		  datalen);
561 }
562 
563 
564 /*
565  * Process an incoming neighbor-list message.
566  */
567 void accept_neighbors(src, dst, p, datalen, level)
568     u_long src, dst, level;
569     char *p;
570     int datalen;
571 {
572     log(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list from %s to %s",
573 	inet_fmt(src, s1), inet_fmt(dst, s2));
574 }
575 
576 /*
577  * Process an incoming neighbor-list message.
578  */
579 void accept_neighbors2(src, dst, p, datalen, level)
580     u_long src, dst, level;
581     char *p;
582     int datalen;
583 {
584     log(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list2 from %s to %s",
585 	inet_fmt(src, s1), inet_fmt(dst, s2));
586 }
587 
588 
589 /*
590  * Update the neighbor entry for neighbor 'addr' on vif 'vifi'.
591  * 'msgtype' is the type of DVMRP message received from the neighbor.
592  * Return TRUE if 'addr' is a valid neighbor, FALSE otherwise.
593  */
594 int update_neighbor(vifi, addr, msgtype)
595     vifi_t vifi;
596     u_long addr;
597     int msgtype;
598 {
599     register struct uvif *v;
600     register struct listaddr *n;
601 
602     v = &uvifs[vifi];
603 
604     /*
605      * Confirm that 'addr' is a valid neighbor address on vif 'vifi'.
606      * IT IS ASSUMED that this was preceded by a call to find_vif(), which
607      * checks that 'addr' is either a valid remote tunnel endpoint or a
608      * non-broadcast address belonging to a directly-connected subnet.
609      * Therefore, here we check only that 'addr' is not our own address
610      * (due to an impostor or erroneous loopback) or an address of the form
611      * {subnet,0} ("the unknown host").  These checks are not performed in
612      * find_vif() because those types of address are acceptable for some
613      * types of IGMP message (such as group membership reports).
614      */
615     if (!(v->uv_flags & VIFF_TUNNEL) &&
616 	(addr == v->uv_lcl_addr ||
617 	 addr == v->uv_subnet )) {
618 	log(LOG_WARNING, 0,
619 	    "received DVMRP message from 'the unknown host' or self: %s",
620 	    inet_fmt(addr, s1));
621 	return (FALSE);
622     }
623 
624     /*
625      * If we have received a route report from a neighbor, and we believed
626      * that we had no neighbors on this vif, send a full route report to
627      * all neighbors on the vif.
628      */
629 
630     if (msgtype == DVMRP_REPORT && v->uv_neighbors == NULL)
631 	report(ALL_ROUTES, vifi,
632 	       (v->uv_flags & VIFF_TUNNEL) ? addr : dvmrp_group);
633 
634     /*
635      * Look for addr in list of neighbors; if found, reset its timer.
636      */
637     for (n = v->uv_neighbors; n != NULL; n = n->al_next) {
638 	if (addr == n->al_addr) {
639 	    n->al_timer = 0;
640 	    break;
641 	}
642     }
643 
644     /*
645      * If not found, add it to the list.  If the neighbor has a lower
646      * IP address than me, yield querier duties to it.
647      */
648     if (n == NULL) {
649 	n = (struct listaddr *)malloc(sizeof(struct listaddr));
650 	if (n == NULL)
651 	    log(LOG_ERR, 0, "ran out of memory");    /* fatal */
652 
653 	n->al_addr      = addr;
654 	n->al_timer     = 0;
655 	n->al_next      = v->uv_neighbors;
656 	v->uv_neighbors = n;
657 
658 	if (!(v->uv_flags & VIFF_TUNNEL) &&
659 	    ntohl(addr) < ntohl(v->uv_lcl_addr))
660 	    v->uv_flags &= ~VIFF_QUERIER;
661     }
662 
663     return (TRUE);
664 }
665 
666 
667 /*
668  * On every timer interrupt, advance the timer in each neighbor and
669  * group entry on every vif.
670  */
671 void age_vifs()
672 {
673     register vifi_t vifi;
674     register struct uvif *v;
675     register struct listaddr *a, *prev_a, *n;
676     register u_long addr;
677 
678     for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v ) {
679 
680 	for (prev_a = (struct listaddr *)&(v->uv_neighbors),
681 	     a = v->uv_neighbors;
682 	     a != NULL;
683 	     prev_a = a, a = a->al_next) {
684 
685 	    if ((a->al_timer += TIMER_INTERVAL) < NEIGHBOR_EXPIRE_TIME)
686 		continue;
687 
688 	    /*
689 	     * Neighbor has expired; delete it from the neighbor list,
690 	     * delete it from the 'dominants' and 'subordinates arrays of
691 	     * any route entries and assume querier duties unless there is
692 	     * another neighbor with a lower IP address than mine.
693 	     */
694 	    addr = a->al_addr;
695 	    prev_a->al_next = a->al_next;
696 	    free((char *)a);
697 	    a = prev_a;
698 
699 	    delete_neighbor_from_routes(addr, vifi);
700 
701 	    if (!(v->uv_flags & VIFF_TUNNEL)) {
702 		v->uv_flags |= VIFF_QUERIER;
703 		for (n = v->uv_neighbors; n != NULL; n = n->al_next) {
704 		    if (ntohl(n->al_addr) < ntohl(v->uv_lcl_addr)) {
705 			v->uv_flags &= ~VIFF_QUERIER;
706 			break;
707 		    }
708 		}
709 	    }
710 	}
711 
712 	for (prev_a = (struct listaddr *)&(v->uv_groups),
713 	     a = v->uv_groups;
714 	     a != NULL;
715 	     prev_a = a, a = a->al_next) {
716 
717 	    if ((a->al_timer += TIMER_INTERVAL) < GROUP_EXPIRE_TIME)
718 		continue;
719 
720 	    /*
721 	     * Group has expired; tell kernel and delete from group list.
722 	     */
723 	    k_del_group(vifi, a->al_addr);
724 
725 	    prev_a->al_next = a->al_next;
726 	    free((char *)a);
727 	    a = prev_a;
728 	}
729     }
730 }
731 
732 
733 /*
734  * Print the contents of the uvifs array on file 'fp'.
735  */
736 void dump_vifs(fp)
737     FILE *fp;
738 {
739     register vifi_t vifi;
740     register struct uvif *v;
741     register struct listaddr *a;
742 
743     fprintf(fp,
744     "\nVirtual Interface Table\n%s",
745     " Vif  Local-Address                           Metric  Thresh  Flags\n");
746 
747     for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
748 
749 	fprintf(fp, " %2u   %-15s %6s: %-15s %4u %7u   ",
750 		vifi,
751 		inet_fmt(v->uv_lcl_addr, s1),
752 		(v->uv_flags & VIFF_TUNNEL) ?
753 			"tunnel":
754 			"subnet",
755 		(v->uv_flags & VIFF_TUNNEL) ?
756 			inet_fmt(v->uv_rmt_addr, s2) :
757 			inet_fmts(v->uv_subnet, v->uv_subnetmask, s3),
758 		v->uv_metric,
759 		v->uv_threshold);
760 
761 	if (v->uv_flags & VIFF_DOWN)     fprintf(fp, " down");
762 	if (v->uv_flags & VIFF_DISABLED) fprintf(fp, " disabled");
763 	if (v->uv_flags & VIFF_QUERIER)  fprintf(fp, " querier");
764 	if (v->uv_flags & VIFF_SRCRT)    fprintf(fp, " src-rt");
765 	fprintf(fp, "\n");
766 
767 	if (v->uv_neighbors != NULL) {
768 	    fprintf(fp, "                      peers : %-15s\n",
769 		    inet_fmt(v->uv_neighbors->al_addr, s1));
770 	    for (a = v->uv_neighbors->al_next; a != NULL; a = a->al_next) {
771 		fprintf(fp, "                              %-15s\n",
772 			inet_fmt(a->al_addr, s1));
773 	    }
774 	}
775 
776 	if (v->uv_groups != NULL) {
777 	    fprintf(fp, "                      groups: %-15s\n",
778 		    inet_fmt(v->uv_groups->al_addr, s1));
779 	    for (a = v->uv_groups->al_next; a != NULL; a = a->al_next) {
780 		fprintf(fp, "                              %-15s\n",
781 			inet_fmt(a->al_addr, s1));
782 	    }
783 	}
784     }
785     fprintf(fp, "\n");
786 }
787