xref: /netbsd-src/sbin/routed/if.c (revision 481fca6e59249d8ffcf24fef7cfbe7b131bfb080)
1 /*	$NetBSD: if.c,v 1.20 2000/06/11 23:43:17 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 1983, 1993
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 #if !defined(lint) && !defined(sgi) && !defined(__NetBSD__)
37 static char sccsid[] __attribute__((unused)) = "@(#)if.c	8.1 (Berkeley) 6/5/93";
38 #elif defined(__NetBSD__)
39 #include <sys/cdefs.h>
40 __RCSID("$NetBSD: if.c,v 1.20 2000/06/11 23:43:17 christos Exp $");
41 #endif
42 
43 #include "defs.h"
44 #include "pathnames.h"
45 
46 struct interface *ifnet;		/* all interfaces */
47 
48 /* hash table for all interfaces, big enough to tolerate ridiculous
49  * numbers of IP aliases.  Crazy numbers of aliases such as 7000
50  * still will not do well, but not just in looking up interfaces
51  * by name or address.
52  */
53 #define AHASH_LEN 211			/* must be prime */
54 #define AHASH(a) &ahash_tbl[(a)%AHASH_LEN]
55 struct interface *ahash_tbl[AHASH_LEN];
56 
57 #define BHASH_LEN 211			/* must be prime */
58 #define BHASH(a) &bhash_tbl[(a)%BHASH_LEN]
59 struct interface *bhash_tbl[BHASH_LEN];
60 
61 struct interface *remote_if;		/* remote interfaces */
62 
63 /* hash for physical interface names.
64  * Assume there are never more 100 or 200 real interfaces, and that
65  * aliases are put on the end of the hash chains.
66  */
67 #define NHASH_LEN 97
68 struct interface *nhash_tbl[NHASH_LEN];
69 
70 int	tot_interfaces;			/* # of remote and local interfaces */
71 int	rip_interfaces;			/* # of interfaces doing RIP */
72 int	foundloopback;			/* valid flag for loopaddr */
73 naddr	loopaddr;			/* our address on loopback */
74 struct	rt_spare loop_rts;
75 
76 struct timeval ifinit_timer;
77 static struct timeval last_ifinit;
78 #define IF_RESCAN_DELAY() (last_ifinit.tv_sec == now.tv_sec		\
79 			   && last_ifinit.tv_usec == now.tv_usec	\
80 			   && timercmp(&ifinit_timer, &now, >))
81 
82 int	have_ripv1_out;			/* have a RIPv1 interface */
83 int	have_ripv1_in;
84 
85 
86 static struct interface**
87 nhash(char *p)
88 {
89 	u_int i;
90 
91 	for (i = 0; *p != '\0'; p++) {
92 		i = ((i<<1) & 0x7fffffff) | ((i>>31) & 1);
93 		i ^= *p;
94 	}
95 	return &nhash_tbl[i % NHASH_LEN];
96 }
97 
98 
99 /* Link a new interface into the lists and hash tables.
100  */
101 void
102 if_link(struct interface *ifp)
103 {
104 	struct interface **hifp;
105 
106 	ifp->int_prev = &ifnet;
107 	ifp->int_next = ifnet;
108 	if (ifnet != 0)
109 		ifnet->int_prev = &ifp->int_next;
110 	ifnet = ifp;
111 
112 	hifp = AHASH(ifp->int_addr);
113 	ifp->int_ahash_prev = hifp;
114 	if ((ifp->int_ahash = *hifp) != 0)
115 		(*hifp)->int_ahash_prev = &ifp->int_ahash;
116 	*hifp = ifp;
117 
118 	if (ifp->int_if_flags & IFF_BROADCAST) {
119 		hifp = BHASH(ifp->int_brdaddr);
120 		ifp->int_bhash_prev = hifp;
121 		if ((ifp->int_bhash = *hifp) != 0)
122 			(*hifp)->int_bhash_prev = &ifp->int_bhash;
123 		*hifp = ifp;
124 	}
125 
126 	if (ifp->int_state & IS_REMOTE) {
127 		ifp->int_rlink_prev = &remote_if;
128 		ifp->int_rlink = remote_if;
129 		if (remote_if != 0)
130 			remote_if->int_rlink_prev = &ifp->int_rlink;
131 		remote_if = ifp;
132 	}
133 
134 	hifp = nhash(ifp->int_name);
135 	if (ifp->int_state & IS_ALIAS) {
136 		/* put aliases on the end of the hash chain */
137 		while (*hifp != 0)
138 			hifp = &(*hifp)->int_nhash;
139 	}
140 	ifp->int_nhash_prev = hifp;
141 	if ((ifp->int_nhash = *hifp) != 0)
142 		(*hifp)->int_nhash_prev = &ifp->int_nhash;
143 	*hifp = ifp;
144 }
145 
146 
147 /* Find the interface with an address
148  */
149 struct interface *
150 ifwithaddr(naddr addr,
151 	   int	bcast,			/* notice IFF_BROADCAST address */
152 	   int	remote)			/* include IS_REMOTE interfaces */
153 {
154 	struct interface *ifp, *possible = 0;
155 
156 	remote = (remote == 0) ? IS_REMOTE : 0;
157 
158 	for (ifp = *AHASH(addr); ifp; ifp = ifp->int_ahash) {
159 		if (ifp->int_addr != addr)
160 			continue;
161 		if ((ifp->int_state & remote) != 0)
162 			continue;
163 		if ((ifp->int_state & (IS_BROKE | IS_PASSIVE)) == 0)
164 			return ifp;
165 		possible = ifp;
166 	}
167 
168 	if (possible || !bcast)
169 		return possible;
170 
171 	for (ifp = *BHASH(addr); ifp; ifp = ifp->int_bhash) {
172 		if (ifp->int_brdaddr != addr)
173 			continue;
174 		if ((ifp->int_state & remote) != 0)
175 			continue;
176 		if ((ifp->int_state & (IS_BROKE | IS_PASSIVE)) == 0)
177 			return ifp;
178 		possible = ifp;
179 	}
180 
181 	return possible;
182 }
183 
184 
185 /* find the interface with a name
186  */
187 struct interface *
188 ifwithname(char *name,			/* "ec0" or whatever */
189 	   naddr addr)			/* 0 or network address */
190 {
191 	struct interface *ifp;
192 
193 	for (;;) {
194 		for (ifp = *nhash(name); ifp != 0; ifp = ifp->int_nhash) {
195 			/* If the network address is not specified,
196 			 * ignore any alias interfaces.  Otherwise, look
197 			 * for the interface with the target name and address.
198 			 */
199 			if (!strcmp(ifp->int_name, name)
200 			    && ((addr == 0 && !(ifp->int_state & IS_ALIAS))
201 				|| (ifp->int_addr == addr)))
202 				return ifp;
203 		}
204 
205 		/* If there is no known interface, maybe there is a
206 		 * new interface.  So just once look for new interfaces.
207 		 */
208 		if (IF_RESCAN_DELAY())
209 			return 0;
210 		ifinit();
211 	}
212 }
213 
214 
215 struct interface *
216 ifwithindex(u_short index,
217 	    int rescan_ok)
218 {
219 	struct interface *ifp;
220 
221 	for (;;) {
222 		for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next) {
223 			if (ifp->int_index == index)
224 				return ifp;
225 		}
226 
227 		/* If there is no known interface, maybe there is a
228 		 * new interface.  So just once look for new interfaces.
229 		 */
230 		if (!rescan_ok
231 		    || IF_RESCAN_DELAY())
232 			return 0;
233 		ifinit();
234 	}
235 }
236 
237 
238 /* Find an interface from which the specified address
239  * should have come from.  Used for figuring out which
240  * interface a packet came in on.
241  */
242 struct interface *
243 iflookup(naddr addr)
244 {
245 	struct interface *ifp, *maybe;
246 	int once = 0;
247 
248 	maybe = 0;
249 	for (;;) {
250 		for (ifp = ifnet; ifp; ifp = ifp->int_next) {
251 			if (ifp->int_if_flags & IFF_POINTOPOINT) {
252 				/* finished with a match */
253 				if (ifp->int_dstaddr == addr)
254 					return ifp;
255 
256 			} else {
257 				/* finished with an exact match */
258 				if (ifp->int_addr == addr)
259 					return ifp;
260 
261 				/* Look for the longest approximate match.
262 				 */
263 				if (on_net(addr, ifp->int_net, ifp->int_mask)
264 				    && (maybe == 0
265 					|| ifp->int_mask > maybe->int_mask))
266 					maybe = ifp;
267 			}
268 		}
269 
270 		if (maybe != 0 || once)
271 			return maybe;
272 
273 		/* If there is no known interface, maybe there is a
274 		 * new interface.  So just once look for new interfaces.
275 		 */
276 		ifinit();
277 		once = 1;
278 	}
279 }
280 
281 
282 /* Return the classical netmask for an IP address.
283  */
284 naddr					/* host byte order */
285 std_mask(naddr addr)			/* network byte order */
286 {
287 	NTOHL(addr);			/* was a host, not a network */
288 
289 	if (addr == 0)			/* default route has mask 0 */
290 		return 0;
291 	if (IN_CLASSA(addr))
292 		return IN_CLASSA_NET;
293 	if (IN_CLASSB(addr))
294 		return IN_CLASSB_NET;
295 	return IN_CLASSC_NET;
296 }
297 
298 
299 /* Find the netmask that would be inferred by RIPv1 listeners
300  *	on the given interface for a given network.
301  *	If no interface is specified, look for the best fitting	interface.
302  */
303 naddr
304 ripv1_mask_net(naddr addr,		/* in network byte order */
305 	       struct interface *ifp)	/* as seen on this interface */
306 {
307 	struct r1net *r1p;
308 	naddr mask = 0;
309 
310 	if (addr == 0)			/* default always has 0 mask */
311 		return mask;
312 
313 	if (ifp != 0 && ifp->int_ripv1_mask != HOST_MASK) {
314 		/* If the target network is that of the associated interface
315 		 * on which it arrived, then use the netmask of the interface.
316 		 */
317 		if (on_net(addr, ifp->int_net, ifp->int_std_mask))
318 			mask = ifp->int_ripv1_mask;
319 
320 	} else {
321 		/* Examine all interfaces, and if it the target seems
322 		 * to have the same network number of an interface, use the
323 		 * netmask of that interface.  If there is more than one
324 		 * such interface, prefer the interface with the longest
325 		 * match.
326 		 */
327 		for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
328 			if (on_net(addr, ifp->int_std_net, ifp->int_std_mask)
329 			    && ifp->int_ripv1_mask > mask
330 			    && ifp->int_ripv1_mask != HOST_MASK)
331 				mask = ifp->int_ripv1_mask;
332 		}
333 
334 	}
335 
336 	/* check special definitions */
337 	if (mask == 0) {
338 		for (r1p = r1nets; r1p != 0; r1p = r1p->r1net_next) {
339 			if (on_net(addr, r1p->r1net_net, r1p->r1net_match)
340 			    && r1p->r1net_mask > mask)
341 				mask = r1p->r1net_mask;
342 		}
343 
344 		/* Otherwise, make the classic A/B/C guess.
345 		 */
346 		if (mask == 0)
347 			mask = std_mask(addr);
348 	}
349 
350 	return mask;
351 }
352 
353 
354 naddr
355 ripv1_mask_host(naddr addr,		/* in network byte order */
356 		struct interface *ifp)	/* as seen on this interface */
357 {
358 	naddr mask = ripv1_mask_net(addr, ifp);
359 
360 
361 	/* If the computed netmask does not mask the address,
362 	 * then assume it is a host address
363 	 */
364 	if ((ntohl(addr) & ~mask) != 0)
365 		mask = HOST_MASK;
366 	return mask;
367 }
368 
369 
370 /* See if a IP address looks reasonable as a destination
371  */
372 int					/* 0=bad */
373 check_dst(naddr addr)
374 {
375 	NTOHL(addr);
376 
377 	if (IN_CLASSA(addr)) {
378 		if (addr == 0)
379 			return 1;	/* default */
380 
381 		addr >>= IN_CLASSA_NSHIFT;
382 		return (addr != 0 && addr != IN_LOOPBACKNET);
383 	}
384 
385 	return (IN_CLASSB(addr) || IN_CLASSC(addr));
386 }
387 
388 
389 /* See a new interface duplicates an existing interface.
390  */
391 struct interface *
392 check_dup(naddr addr,			/* IP address, so network byte order */
393 	  naddr dstaddr,		/* ditto */
394 	  naddr mask,			/* mask, so host byte order */
395 	  int if_flags)
396 {
397 	struct interface *ifp;
398 
399 	for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next) {
400 		if (ifp->int_mask != mask)
401 			continue;
402 
403 		if (!iff_up(ifp->int_if_flags))
404 			continue;
405 
406 		/* The local address can only be shared with a point-to-point
407 		 * link.
408 		 */
409 		if (ifp->int_addr == addr
410 		    && (((if_flags|ifp->int_if_flags) & IFF_POINTOPOINT) == 0))
411 			return ifp;
412 
413 		if (on_net(ifp->int_dstaddr, ntohl(dstaddr),mask))
414 			return ifp;
415 	}
416 	return 0;
417 }
418 
419 
420 /* See that a remote gateway is reachable.
421  *	Note that the answer can change as real interfaces come and go.
422  */
423 int					/* 0=bad */
424 check_remote(struct interface *ifp)
425 {
426 	struct rt_entry *rt;
427 
428 	/* do not worry about other kinds */
429 	if (!(ifp->int_state & IS_REMOTE))
430 	    return 1;
431 
432 	rt = rtfind(ifp->int_addr);
433 	if (rt != 0
434 	    && rt->rt_ifp != 0
435 	    &&on_net(ifp->int_addr,
436 		     rt->rt_ifp->int_net, rt->rt_ifp->int_mask))
437 		return 1;
438 
439 	/* the gateway cannot be reached directly from one of our
440 	 * interfaces
441 	 */
442 	if (!(ifp->int_state & IS_BROKE)) {
443 		msglog("unreachable gateway %s in "_PATH_GATEWAYS,
444 		       naddr_ntoa(ifp->int_addr));
445 		if_bad(ifp);
446 	}
447 	return 0;
448 }
449 
450 
451 /* Delete an interface.
452  */
453 static void
454 ifdel(struct interface *ifp)
455 {
456 	struct ip_mreq m;
457 	struct interface *ifp1;
458 
459 
460 	trace_if("Del", ifp);
461 
462 	ifp->int_state |= IS_BROKE;
463 
464 	/* unlink the interface
465 	 */
466 	*ifp->int_prev = ifp->int_next;
467 	if (ifp->int_next != 0)
468 		ifp->int_next->int_prev = ifp->int_prev;
469 	*ifp->int_ahash_prev = ifp->int_ahash;
470 	if (ifp->int_ahash != 0)
471 		ifp->int_ahash->int_ahash_prev = ifp->int_ahash_prev;
472 	*ifp->int_nhash_prev = ifp->int_nhash;
473 	if (ifp->int_nhash != 0)
474 		ifp->int_nhash->int_nhash_prev = ifp->int_nhash_prev;
475 	if (ifp->int_if_flags & IFF_BROADCAST) {
476 		*ifp->int_bhash_prev = ifp->int_bhash;
477 		if (ifp->int_bhash != 0)
478 			ifp->int_bhash->int_bhash_prev = ifp->int_bhash_prev;
479 	}
480 	if (ifp->int_state & IS_REMOTE) {
481 		*ifp->int_rlink_prev = ifp->int_rlink;
482 		if (ifp->int_rlink != 0)
483 			ifp->int_rlink->int_rlink_prev = ifp->int_rlink_prev;
484 	}
485 
486 	if (!(ifp->int_state & IS_ALIAS)) {
487 		/* delete aliases when the main interface dies
488 		 */
489 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
490 			if (ifp1 != ifp
491 			    && !strcmp(ifp->int_name, ifp1->int_name))
492 				ifdel(ifp1);
493 		}
494 
495 		if ((ifp->int_if_flags & IFF_MULTICAST)
496 #ifdef MCAST_PPP_BUG
497 		    && !(ifp->int_if_flags & IFF_POINTOPOINT)
498 #endif
499 		    && rip_sock >= 0) {
500 			m.imr_multiaddr.s_addr = htonl(INADDR_RIP_GROUP);
501 			m.imr_interface.s_addr = ((ifp->int_if_flags
502 						   & IFF_POINTOPOINT)
503 						  ? ifp->int_dstaddr
504 						  : ifp->int_addr);
505 			if (setsockopt(rip_sock,IPPROTO_IP,IP_DROP_MEMBERSHIP,
506 				       &m, sizeof(m)) < 0
507 			    && errno != EADDRNOTAVAIL
508 			    && !TRACEACTIONS)
509 				LOGERR("setsockopt(IP_DROP_MEMBERSHIP RIP)");
510 			if (rip_sock_mcast == ifp)
511 				rip_sock_mcast = 0;
512 		}
513 		if (ifp->int_rip_sock >= 0) {
514 			(void)close(ifp->int_rip_sock);
515 			ifp->int_rip_sock = -1;
516 			fix_select();
517 		}
518 
519 		tot_interfaces--;
520 		if (!IS_RIP_OFF(ifp->int_state))
521 			rip_interfaces--;
522 
523 		/* Zap all routes associated with this interface.
524 		 * Assume routes just using gateways beyond this interface
525 		 * will timeout naturally, and have probably already died.
526 		 */
527 		(void)rn_walktree(rhead, walk_bad, 0);
528 
529 		set_rdisc_mg(ifp, 0);
530 		if_bad_rdisc(ifp);
531 	}
532 
533 	free(ifp);
534 }
535 
536 
537 /* Mark an interface ill.
538  */
539 void
540 if_sick(struct interface *ifp)
541 {
542 	if (0 == (ifp->int_state & (IS_SICK | IS_BROKE))) {
543 		ifp->int_state |= IS_SICK;
544 		ifp->int_act_time = NEVER;
545 		trace_if("Chg", ifp);
546 
547 		LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
548 	}
549 }
550 
551 
552 /* Mark an interface dead.
553  */
554 void
555 if_bad(struct interface *ifp)
556 {
557 	struct interface *ifp1;
558 
559 
560 	if (ifp->int_state & IS_BROKE)
561 		return;
562 
563 	LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
564 
565 	ifp->int_state |= (IS_BROKE | IS_SICK);
566 	ifp->int_act_time = NEVER;
567 	ifp->int_query_time = NEVER;
568 	ifp->int_data.ts = now.tv_sec;
569 
570 	trace_if("Chg", ifp);
571 
572 	if (!(ifp->int_state & IS_ALIAS)) {
573 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
574 			if (ifp1 != ifp
575 			    && !strcmp(ifp->int_name, ifp1->int_name))
576 				if_bad(ifp1);
577 		}
578 		(void)rn_walktree(rhead, walk_bad, 0);
579 		if_bad_rdisc(ifp);
580 	}
581 }
582 
583 
584 /* Mark an interface alive
585  */
586 int					/* 1=it was dead */
587 if_ok(struct interface *ifp,
588       const char *type)
589 {
590 	struct interface *ifp1;
591 
592 
593 	if (!(ifp->int_state & IS_BROKE)) {
594 		if (ifp->int_state & IS_SICK) {
595 			trace_act("%sinterface %s to %s working better",
596 				  type,
597 				  ifp->int_name, naddr_ntoa(ifp->int_dstaddr));
598 			ifp->int_state &= ~IS_SICK;
599 		}
600 		return 0;
601 	}
602 
603 	msglog("%sinterface %s to %s restored",
604 	       type, ifp->int_name, naddr_ntoa(ifp->int_dstaddr));
605 	ifp->int_state &= ~(IS_BROKE | IS_SICK);
606 	ifp->int_data.ts = 0;
607 
608 	if (!(ifp->int_state & IS_ALIAS)) {
609 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
610 			if (ifp1 != ifp
611 			    && !strcmp(ifp->int_name, ifp1->int_name))
612 				if_ok(ifp1, type);
613 		}
614 		if_ok_rdisc(ifp);
615 	}
616 
617 	if (ifp->int_state & IS_REMOTE) {
618 		if (!addrouteforif(ifp))
619 			return 0;
620 	}
621 	return 1;
622 }
623 
624 
625 /* disassemble routing message
626  */
627 void
628 rt_xaddrs(struct rt_addrinfo *info,
629 	  struct sockaddr *sa,
630 	  struct sockaddr *lim,
631 	  int addrs)
632 {
633 	int i;
634 #ifdef _HAVE_SA_LEN
635 	static struct sockaddr sa_zero;
636 #endif
637 #ifdef sgi
638 #define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(__uint64_t) - 1))) \
639 		    : sizeof(__uint64_t))
640 #else
641 #define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) \
642 		    : sizeof(long))
643 #endif
644 
645 
646 	memset(info, 0, sizeof(*info));
647 	info->rti_addrs = addrs;
648 	for (i = 0; i < RTAX_MAX && sa < lim; i++) {
649 		if ((addrs & (1 << i)) == 0)
650 			continue;
651 #ifdef _HAVE_SA_LEN
652 		info->rti_info[i] = (sa->sa_len != 0) ? sa : &sa_zero;
653 		sa = (struct sockaddr *)((char*)(sa)
654 					 + ROUNDUP(sa->sa_len));
655 #else
656 		info->rti_info[i] = sa;
657 		sa = (struct sockaddr *)((char*)(sa)
658 					 + ROUNDUP(_FAKE_SA_LEN_DST(sa)));
659 #endif
660 	}
661 }
662 
663 
664 /* Find the network interfaces which have configured themselves.
665  *	This must be done regularly, if only for extra addresses
666  *	that come and go on interfaces.
667  */
668 void
669 ifinit(void)
670 {
671 	static char *sysctl_buf;
672 	static size_t sysctl_buf_size = 0;
673 	uint complaints = 0;
674 	static u_int prev_complaints = 0;
675 #	define COMP_NOT_INET	0x001
676 #	define COMP_NOADDR	0x002
677 #	define COMP_BADADDR	0x004
678 #	define COMP_NODST	0x008
679 #	define COMP_NOBADR	0x010
680 #	define COMP_NOMASK	0x020
681 #	define COMP_DUP		0x040
682 #	define COMP_BAD_METRIC	0x080
683 #	define COMP_NETMASK	0x100
684 
685 	struct interface ifs, ifs0, *ifp, *ifp1;
686 	struct rt_entry *rt;
687 	size_t needed;
688 	int mib[6];
689 	struct if_msghdr *ifm;
690 	struct ifa_msghdr *ifam, *ifam_lim, *ifam2;
691 	int in, ierr, out, oerr;
692 	struct intnet *intnetp;
693 	struct rt_addrinfo info;
694 #ifdef SIOCGIFMETRIC
695 	struct ifreq ifr;
696 #endif
697 
698 
699 	last_ifinit = now;
700 	ifinit_timer.tv_sec = now.tv_sec + (supplier
701 					    ? CHECK_ACT_INTERVAL
702 					    : CHECK_QUIET_INTERVAL);
703 
704 	/* mark all interfaces so we can get rid of those that disappear */
705 	for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next)
706 		ifp->int_state &= ~(IS_CHECKED | IS_DUP);
707 
708 	/* Fetch the interface list, without too many system calls
709 	 * since we do it repeatedly.
710 	 */
711 	mib[0] = CTL_NET;
712 	mib[1] = PF_ROUTE;
713 	mib[2] = 0;
714 	mib[3] = AF_INET;
715 	mib[4] = NET_RT_IFLIST;
716 	mib[5] = 0;
717 	for (;;) {
718 		if ((needed = sysctl_buf_size) != 0) {
719 			if (sysctl(mib, 6, sysctl_buf,&needed, 0, 0) >= 0)
720 				break;
721 			/* retry if the table grew */
722 			if (errno != ENOMEM && errno != EFAULT)
723 				BADERR(1, "ifinit: sysctl(RT_IFLIST)");
724 			free(sysctl_buf);
725 			needed = 0;
726 		}
727 		if (sysctl(mib, 6, 0, &needed, 0, 0) < 0)
728 			BADERR(1,"ifinit: sysctl(RT_IFLIST) estimate");
729 		sysctl_buf = rtmalloc(sysctl_buf_size = needed,
730 				      "ifinit sysctl");
731 	}
732 
733 	ifam_lim = (struct ifa_msghdr *)(sysctl_buf + needed);
734 	for (ifam = (struct ifa_msghdr *)sysctl_buf;
735 	     ifam < ifam_lim;
736 	     ifam = ifam2) {
737 
738 		ifam2 = (struct ifa_msghdr*)((char*)ifam + ifam->ifam_msglen);
739 
740 #ifdef RTM_OIFINFO
741 		if (ifam->ifam_type == RTM_OIFINFO) {
742 			continue; /* just ignore compat message */
743 		}
744 #endif
745 		if (ifam->ifam_type == RTM_IFINFO) {
746 			struct sockaddr_dl *sdl;
747 
748 			ifm = (struct if_msghdr *)ifam;
749 			/* make prototype structure for the IP aliases
750 			 */
751 			memset(&ifs0, 0, sizeof(ifs0));
752 			ifs0.int_rip_sock = -1;
753 			ifs0.int_index = ifm->ifm_index;
754 			ifs0.int_if_flags = ifm->ifm_flags;
755 			ifs0.int_state = IS_CHECKED;
756 			ifs0.int_query_time = NEVER;
757 			ifs0.int_act_time = now.tv_sec;
758 			ifs0.int_data.ts = now.tv_sec;
759 			ifs0.int_data.ipackets = ifm->ifm_data.ifi_ipackets;
760 			ifs0.int_data.ierrors = ifm->ifm_data.ifi_ierrors;
761 			ifs0.int_data.opackets = ifm->ifm_data.ifi_opackets;
762 			ifs0.int_data.oerrors = ifm->ifm_data.ifi_oerrors;
763 #ifdef sgi
764 			ifs0.int_data.odrops = ifm->ifm_data.ifi_odrops;
765 #endif
766 			sdl = (struct sockaddr_dl *)(ifm + 1);
767 			sdl->sdl_data[sdl->sdl_nlen] = 0;
768 			strncpy(ifs0.int_name, sdl->sdl_data,
769 				MIN(sizeof(ifs0.int_name), sdl->sdl_nlen));
770 			continue;
771 		}
772 		if (ifam->ifam_type != RTM_NEWADDR) {
773 			logbad(1,"ifinit: out of sync");
774 			continue;
775 		}
776 		rt_xaddrs(&info, (struct sockaddr *)(ifam+1),
777 			  (struct sockaddr *)ifam2,
778 			  ifam->ifam_addrs);
779 
780 		/* Prepare for the next address of this interface, which
781 		 * will be an alias.
782 		 * Do not output RIP or Router-Discovery packets via aliases.
783 		 */
784 		memcpy(&ifs, &ifs0, sizeof(ifs));
785 		ifs0.int_state |= (IS_ALIAS | IS_NO_RIP_OUT | IS_NO_RDISC);
786 
787 		if (INFO_IFA(&info) == 0) {
788 			if (iff_up(ifs.int_if_flags)) {
789 				if (!(prev_complaints & COMP_NOADDR))
790 					msglog("%s has no address",
791 					       ifs.int_name);
792 				complaints |= COMP_NOADDR;
793 			}
794 			continue;
795 		}
796 		if (INFO_IFA(&info)->sa_family != AF_INET) {
797 			if (iff_up(ifs.int_if_flags)) {
798 				if (!(prev_complaints & COMP_NOT_INET))
799 					trace_act("%s: not AF_INET",
800 						  ifs.int_name);
801 				complaints |= COMP_NOT_INET;
802 			}
803 			continue;
804 		}
805 
806 		ifs.int_addr = S_ADDR(INFO_IFA(&info));
807 
808 		if (ntohl(ifs.int_addr)>>24 == 0
809 		    || ntohl(ifs.int_addr)>>24 == 0xff) {
810 			if (iff_up(ifs.int_if_flags)) {
811 				if (!(prev_complaints & COMP_BADADDR))
812 					msglog("%s has a bad address",
813 					       ifs.int_name);
814 				complaints |= COMP_BADADDR;
815 			}
816 			continue;
817 		}
818 
819 		if (ifs.int_if_flags & IFF_LOOPBACK) {
820 			ifs.int_state |= IS_PASSIVE | IS_NO_RIP | IS_NO_RDISC;
821 			ifs.int_dstaddr = ifs.int_addr;
822 			ifs.int_mask = HOST_MASK;
823 			ifs.int_ripv1_mask = HOST_MASK;
824 			ifs.int_std_mask = std_mask(ifs.int_dstaddr);
825 			ifs.int_net = ntohl(ifs.int_dstaddr);
826 			if (!foundloopback) {
827 				foundloopback = 1;
828 				loopaddr = ifs.int_addr;
829 				loop_rts.rts_gate = loopaddr;
830 				loop_rts.rts_router = loopaddr;
831 			}
832 
833 		} else if (ifs.int_if_flags & IFF_POINTOPOINT) {
834 			if (INFO_BRD(&info) == 0
835 			    || INFO_BRD(&info)->sa_family != AF_INET) {
836 				if (iff_up(ifs.int_if_flags)) {
837 					if (!(prev_complaints & COMP_NODST))
838 						msglog("%s has a bad"
839 						       " destination address",
840 						       ifs.int_name);
841 					complaints |= COMP_NODST;
842 				}
843 				continue;
844 			}
845 			ifs.int_dstaddr = S_ADDR(INFO_BRD(&info));
846 			if (ntohl(ifs.int_dstaddr)>>24 == 0
847 			    || ntohl(ifs.int_dstaddr)>>24 == 0xff) {
848 				if (iff_up(ifs.int_if_flags)) {
849 					if (!(prev_complaints & COMP_NODST))
850 						msglog("%s has a bad"
851 						       " destination address",
852 						       ifs.int_name);
853 					complaints |= COMP_NODST;
854 				}
855 				continue;
856 			}
857 			ifs.int_mask = HOST_MASK;
858 			ifs.int_ripv1_mask = ntohl(S_ADDR(INFO_MASK(&info)));
859 			ifs.int_std_mask = std_mask(ifs.int_dstaddr);
860 			ifs.int_net = ntohl(ifs.int_dstaddr);
861 
862 		}  else {
863 			if (INFO_MASK(&info) == 0) {
864 				if (iff_up(ifs.int_if_flags)) {
865 					if (!(prev_complaints & COMP_NOMASK))
866 						msglog("%s has no netmask",
867 						       ifs.int_name);
868 					complaints |= COMP_NOMASK;
869 				}
870 				continue;
871 			}
872 			ifs.int_dstaddr = ifs.int_addr;
873 			ifs.int_mask = ntohl(S_ADDR(INFO_MASK(&info)));
874 			ifs.int_ripv1_mask = ifs.int_mask;
875 			ifs.int_std_mask = std_mask(ifs.int_addr);
876 			ifs.int_net = ntohl(ifs.int_addr) & ifs.int_mask;
877 			if (ifs.int_mask != ifs.int_std_mask)
878 				ifs.int_state |= IS_SUBNET;
879 
880 			if (ifs.int_if_flags & IFF_BROADCAST) {
881 				if (INFO_BRD(&info) == 0) {
882 					if (iff_up(ifs.int_if_flags)) {
883 					    if (!(prev_complaints
884 						  & COMP_NOBADR))
885 						msglog("%s has"
886 						       "no broadcast address",
887 						       ifs.int_name);
888 					    complaints |= COMP_NOBADR;
889 					}
890 					continue;
891 				}
892 				ifs.int_brdaddr = S_ADDR(INFO_BRD(&info));
893 			}
894 		}
895 		ifs.int_std_net = ifs.int_net & ifs.int_std_mask;
896 		ifs.int_std_addr = htonl(ifs.int_std_net);
897 
898 		/* Use a minimum metric of one.  Treat the interface metric
899 		 * (default 0) as an increment to the hop count of one.
900 		 *
901 		 * The metric obtained from the routing socket dump of
902 		 * interface addresses is wrong.  It is not set by the
903 		 * SIOCSIFMETRIC ioctl.
904 		 */
905 #ifdef SIOCGIFMETRIC
906 		strncpy(ifr.ifr_name, ifs.int_name, sizeof(ifr.ifr_name));
907 		if (ioctl(rt_sock, SIOCGIFMETRIC, &ifr) < 0) {
908 			DBGERR(1, "ioctl(SIOCGIFMETRIC)");
909 			ifs.int_metric = 0;
910 		} else {
911 			ifs.int_metric = ifr.ifr_metric;
912 		}
913 #else
914 		ifs.int_metric = ifam->ifam_metric;
915 #endif
916 		if (ifs.int_metric > HOPCNT_INFINITY) {
917 			ifs.int_metric = 0;
918 			if (!(prev_complaints & COMP_BAD_METRIC)
919 			    && iff_up(ifs.int_if_flags)) {
920 				complaints |= COMP_BAD_METRIC;
921 				msglog("%s has a metric of %d",
922 				       ifs.int_name, ifs.int_metric);
923 			}
924 		}
925 
926 		/* See if this is a familiar interface.
927 		 * If so, stop worrying about it if it is the same.
928 		 * Start it over if it now is to somewhere else, as happens
929 		 * frequently with PPP and SLIP.
930 		 */
931 		ifp = ifwithname(ifs.int_name, ((ifs.int_state & IS_ALIAS)
932 						? ifs.int_addr
933 						: 0));
934 		if (ifp != 0) {
935 			ifp->int_state |= IS_CHECKED;
936 
937 			if (0 != ((ifp->int_if_flags ^ ifs.int_if_flags)
938 				  & (IFF_BROADCAST
939 				     | IFF_LOOPBACK
940 				     | IFF_POINTOPOINT
941 				     | IFF_MULTICAST))
942 			    || 0 != ((ifp->int_state ^ ifs.int_state)
943 				     & IS_ALIAS)
944 			    || ifp->int_addr != ifs.int_addr
945 			    || ifp->int_brdaddr != ifs.int_brdaddr
946 			    || ifp->int_dstaddr != ifs.int_dstaddr
947 			    || ifp->int_mask != ifs.int_mask
948 			    || ifp->int_metric != ifs.int_metric) {
949 				/* Forget old information about
950 				 * a changed interface.
951 				 */
952 				trace_act("interface %s has changed",
953 					  ifp->int_name);
954 				ifdel(ifp);
955 				ifp = 0;
956 			}
957 		}
958 
959 		if (ifp != 0) {
960 			/* The primary representative of an alias worries
961 			 * about how things are working.
962 			 */
963 			if (ifp->int_state & IS_ALIAS)
964 				continue;
965 
966 			/* note interfaces that have been turned off
967 			 */
968 			if (!iff_up(ifs.int_if_flags)) {
969 				if (iff_up(ifp->int_if_flags)) {
970 					msglog("interface %s to %s turned off",
971 					       ifp->int_name,
972 					       naddr_ntoa(ifp->int_dstaddr));
973 					if_bad(ifp);
974 					ifp->int_if_flags &= ~IFF_UP;
975 				} else if (now.tv_sec>(ifp->int_data.ts
976 						       + CHECK_BAD_INTERVAL)) {
977 					trace_act("interface %s has been off"
978 						  " %ld seconds; forget it",
979 						  ifp->int_name,
980 						  now.tv_sec-ifp->int_data.ts);
981 					ifdel(ifp);
982 				}
983 				continue;
984 			}
985 			/* or that were off and are now ok */
986 			if (!iff_up(ifp->int_if_flags)) {
987 				ifp->int_if_flags |= IFF_UP;
988 				(void)if_ok(ifp, "");
989 			}
990 
991 			/* If it has been long enough,
992 			 * see if the interface is broken.
993 			 */
994 			if (now.tv_sec < ifp->int_data.ts+CHECK_BAD_INTERVAL)
995 				continue;
996 
997 			in = ifs.int_data.ipackets - ifp->int_data.ipackets;
998 			ierr = ifs.int_data.ierrors - ifp->int_data.ierrors;
999 			out = ifs.int_data.opackets - ifp->int_data.opackets;
1000 			oerr = ifs.int_data.oerrors - ifp->int_data.oerrors;
1001 #ifdef sgi
1002 			/* Through at least IRIX 6.2, PPP and SLIP
1003 			 * count packets dropped by the filters.
1004 			 * But FDDI rings stuck non-operational count
1005 			 * dropped packets as they wait for improvement.
1006 			 */
1007 			if (!(ifp->int_if_flags & IFF_POINTOPOINT))
1008 				oerr += (ifs.int_data.odrops
1009 					 - ifp->int_data.odrops);
1010 #endif
1011 			/* If the interface just awoke, restart the counters.
1012 			 */
1013 			if (ifp->int_data.ts == 0) {
1014 				ifp->int_data = ifs.int_data;
1015 				continue;
1016 			}
1017 			ifp->int_data = ifs.int_data;
1018 
1019 			/* Withhold judgment when the short error
1020 			 * counters wrap or the interface is reset.
1021 			 */
1022 			if (ierr < 0 || in < 0 || oerr < 0 || out < 0) {
1023 				LIM_SEC(ifinit_timer,
1024 					now.tv_sec+CHECK_BAD_INTERVAL);
1025 				continue;
1026 			}
1027 
1028 			/* Withhold judgement when there is no traffic
1029 			 */
1030 			if (in == 0 && out == 0 && ierr == 0 && oerr == 0)
1031 				continue;
1032 
1033 			/* It is bad if input or output is not working.
1034 			 * Require presistent problems before marking it dead.
1035 			 */
1036 			if ((in <= ierr && ierr > 0)
1037 			    || (out <= oerr && oerr > 0)) {
1038 				if (!(ifp->int_state & IS_SICK)) {
1039 					trace_act("interface %s to %s"
1040 						  " sick: in=%d ierr=%d"
1041 						  " out=%d oerr=%d",
1042 						  ifp->int_name,
1043 						  naddr_ntoa(ifp->int_dstaddr),
1044 						  in, ierr, out, oerr);
1045 					if_sick(ifp);
1046 					continue;
1047 				}
1048 				if (!(ifp->int_state & IS_BROKE)) {
1049 					msglog("interface %s to %s broken:"
1050 					       " in=%d ierr=%d out=%d oerr=%d",
1051 					       ifp->int_name,
1052 					       naddr_ntoa(ifp->int_dstaddr),
1053 					       in, ierr, out, oerr);
1054 					if_bad(ifp);
1055 				}
1056 				continue;
1057 			}
1058 
1059 			/* otherwise, it is active and healthy
1060 			 */
1061 			ifp->int_act_time = now.tv_sec;
1062 			(void)if_ok(ifp, "");
1063 			continue;
1064 		}
1065 
1066 		/* This is a new interface.
1067 		 * If it is dead, forget it.
1068 		 */
1069 		if (!iff_up(ifs.int_if_flags))
1070 			continue;
1071 
1072 		/* If it duplicates an existing interface,
1073 		 * complain about it, mark the other one
1074 		 * duplicated, and forget this one.
1075 		 */
1076 		ifp = check_dup(ifs.int_addr,ifs.int_dstaddr,ifs.int_mask,
1077 				ifs.int_if_flags);
1078 		if (ifp != 0) {
1079 			/* Ignore duplicates of itself, caused by having
1080 			 * IP aliases on the same network.
1081 			 */
1082 			if (!strcmp(ifp->int_name, ifs.int_name))
1083 				continue;
1084 
1085 			if (!(prev_complaints & COMP_DUP)) {
1086 				complaints |= COMP_DUP;
1087 				msglog("%s (%s%s%s) is duplicated by"
1088 				       " %s (%s%s%s)",
1089 				       ifs.int_name,
1090 				       addrname(ifs.int_addr,ifs.int_mask,1),
1091 				       ((ifs.int_if_flags & IFF_POINTOPOINT)
1092 					? "-->" : ""),
1093 				       ((ifs.int_if_flags & IFF_POINTOPOINT)
1094 					? naddr_ntoa(ifs.int_dstaddr) : ""),
1095 				       ifp->int_name,
1096 				       addrname(ifp->int_addr,ifp->int_mask,1),
1097 				       ((ifp->int_if_flags & IFF_POINTOPOINT)
1098 					? "-->" : ""),
1099 				       ((ifp->int_if_flags & IFF_POINTOPOINT)
1100 					? naddr_ntoa(ifp->int_dstaddr) : ""));
1101 			}
1102 			ifp->int_state |= IS_DUP;
1103 			continue;
1104 		}
1105 
1106 		if (0 == (ifs.int_if_flags & (IFF_POINTOPOINT | IFF_BROADCAST))
1107 		    && !(ifs.int_state & IS_PASSIVE)) {
1108 			trace_act("%s is neither broadcast, point-to-point,"
1109 				  " nor loopback",
1110 				  ifs.int_name);
1111 			if (!(ifs.int_state & IFF_MULTICAST))
1112 				ifs.int_state |= IS_NO_RDISC;
1113 		}
1114 
1115 
1116 		/* It is new and ok.   Add it to the list of interfaces
1117 		 */
1118 		ifp = (struct interface *)rtmalloc(sizeof(*ifp), "ifinit ifp");
1119 		memcpy(ifp, &ifs, sizeof(*ifp));
1120 		get_parms(ifp);
1121 		if_link(ifp);
1122 		trace_if("Add", ifp);
1123 
1124 		/* Notice likely bad netmask.
1125 		 */
1126 		if (!(prev_complaints & COMP_NETMASK)
1127 		    && !(ifp->int_if_flags & IFF_POINTOPOINT)
1128 		    && ifp->int_addr != RIP_DEFAULT) {
1129 			for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
1130 				if (ifp1->int_mask == ifp->int_mask)
1131 					continue;
1132 				if (ifp1->int_if_flags & IFF_POINTOPOINT)
1133 					continue;
1134 				if (ifp1->int_dstaddr == RIP_DEFAULT)
1135 					continue;
1136 				if (on_net(ifp->int_dstaddr,
1137 					   ifp1->int_net, ifp1->int_mask)
1138 				    || on_net(ifp1->int_dstaddr,
1139 					      ifp->int_net, ifp->int_mask)) {
1140 					msglog("possible netmask problem"
1141 					       " between %s:%s and %s:%s",
1142 					       ifp->int_name,
1143 					       addrname(htonl(ifp->int_net),
1144 							ifp->int_mask, 1),
1145 					       ifp1->int_name,
1146 					       addrname(htonl(ifp1->int_net),
1147 							ifp1->int_mask, 1));
1148 					complaints |= COMP_NETMASK;
1149 				}
1150 			}
1151 		}
1152 
1153 		if (!(ifp->int_state & IS_ALIAS)) {
1154 			/* Count the # of directly connected networks.
1155 			 */
1156 			if (!(ifp->int_if_flags & IFF_LOOPBACK))
1157 				tot_interfaces++;
1158 			if (!IS_RIP_OFF(ifp->int_state))
1159 				rip_interfaces++;
1160 
1161 			/* turn on router discovery and RIP If needed */
1162 			if_ok_rdisc(ifp);
1163 			rip_on(ifp);
1164 		}
1165 	}
1166 
1167 	/* If we are multi-homed and have at least two interfaces
1168 	 * listening to RIP, then output by default.
1169 	 */
1170 	if (!supplier_set && rip_interfaces > 1)
1171 		set_supplier();
1172 
1173 	/* If we are multi-homed, optionally advertise a route to
1174 	 * our main address.
1175 	 */
1176 	if (advertise_mhome
1177 	    || (tot_interfaces > 1
1178 		&& mhome
1179 		&& (ifp = ifwithaddr(myaddr, 0, 0)) != 0
1180 		&& foundloopback)) {
1181 		advertise_mhome = 1;
1182 		rt = rtget(myaddr, HOST_MASK);
1183 		if (rt != 0) {
1184 			if (rt->rt_ifp != ifp
1185 			    || rt->rt_router != loopaddr) {
1186 				rtdelete(rt);
1187 				rt = 0;
1188 			} else {
1189 				loop_rts.rts_ifp = ifp;
1190 				loop_rts.rts_metric = 0;
1191 				loop_rts.rts_time = rt->rt_time;
1192 				rtchange(rt, rt->rt_state | RS_MHOME,
1193 					 &loop_rts, 0);
1194 			}
1195 		}
1196 		if (rt == 0) {
1197 			loop_rts.rts_ifp = ifp;
1198 			loop_rts.rts_metric = 0;
1199 			rtadd(myaddr, HOST_MASK, RS_MHOME, &loop_rts);
1200 		}
1201 	}
1202 
1203 	for (ifp = ifnet; ifp != 0; ifp = ifp1) {
1204 		ifp1 = ifp->int_next;	/* because we may delete it */
1205 
1206 		/* Forget any interfaces that have disappeared.
1207 		 */
1208 		if (!(ifp->int_state & (IS_CHECKED | IS_REMOTE))) {
1209 			trace_act("interface %s has disappeared",
1210 				  ifp->int_name);
1211 			ifdel(ifp);
1212 			continue;
1213 		}
1214 
1215 		if ((ifp->int_state & IS_BROKE)
1216 		    && !(ifp->int_state & IS_PASSIVE))
1217 			LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
1218 
1219 		/* If we ever have a RIPv1 interface, assume we always will.
1220 		 * It might come back if it ever goes away.
1221 		 */
1222 		if (!(ifp->int_state & IS_NO_RIPV1_OUT) && supplier)
1223 			have_ripv1_out = 1;
1224 		if (!(ifp->int_state & IS_NO_RIPV1_IN))
1225 			have_ripv1_in = 1;
1226 	}
1227 
1228 	for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
1229 		/* Ensure there is always a network route for interfaces,
1230 		 * after any dead interfaces have been deleted, which
1231 		 * might affect routes for point-to-point links.
1232 		 */
1233 		if (!addrouteforif(ifp))
1234 			continue;
1235 
1236 		/* Add routes to the local end of point-to-point interfaces
1237 		 * using loopback.
1238 		 */
1239 		if ((ifp->int_if_flags & IFF_POINTOPOINT)
1240 		    && !(ifp->int_state & IS_REMOTE)
1241 		    && foundloopback) {
1242 			/* Delete any routes to the network address through
1243 			 * foreign routers. Remove even static routes.
1244 			 */
1245 			del_static(ifp->int_addr, HOST_MASK, 0, 0);
1246 			rt = rtget(ifp->int_addr, HOST_MASK);
1247 			if (rt != 0 && rt->rt_router != loopaddr) {
1248 				rtdelete(rt);
1249 				rt = 0;
1250 			}
1251 			if (rt != 0) {
1252 				if (!(rt->rt_state & RS_LOCAL)
1253 				    || rt->rt_metric > ifp->int_metric) {
1254 					ifp1 = ifp;
1255 				} else {
1256 					ifp1 = rt->rt_ifp;
1257 				}
1258 				loop_rts.rts_ifp = ifp1;
1259 				loop_rts.rts_metric = 0;
1260 				loop_rts.rts_time = rt->rt_time;
1261 				rtchange(rt, ((rt->rt_state & ~RS_NET_SYN)
1262 					      | (RS_IF|RS_LOCAL)),
1263 					 &loop_rts, 0);
1264 			} else {
1265 				loop_rts.rts_ifp = ifp;
1266 				loop_rts.rts_metric = 0;
1267 				rtadd(ifp->int_addr, HOST_MASK,
1268 				      (RS_IF | RS_LOCAL), &loop_rts);
1269 			}
1270 		}
1271 	}
1272 
1273 	/* add the authority routes */
1274 	for (intnetp = intnets; intnetp!=0; intnetp = intnetp->intnet_next) {
1275 		rt = rtget(intnetp->intnet_addr, intnetp->intnet_mask);
1276 		if (rt != 0
1277 		    && !(rt->rt_state & RS_NO_NET_SYN)
1278 		    && !(rt->rt_state & RS_NET_INT)) {
1279 			rtdelete(rt);
1280 			rt = 0;
1281 		}
1282 		if (rt == 0) {
1283 			loop_rts.rts_ifp = 0;
1284 			loop_rts.rts_metric = intnetp->intnet_metric-1;
1285 			rtadd(intnetp->intnet_addr, intnetp->intnet_mask,
1286 			      RS_NET_SYN | RS_NET_INT, &loop_rts);
1287 		}
1288 	}
1289 
1290 	prev_complaints = complaints;
1291 }
1292 
1293 
1294 static void
1295 check_net_syn(struct interface *ifp)
1296 {
1297 	struct rt_entry *rt;
1298 	static struct rt_spare new;
1299 
1300 
1301 	/* Turn on the need to automatically synthesize a network route
1302 	 * for this interface only if we are running RIPv1 on some other
1303 	 * interface that is on a different class-A,B,or C network.
1304 	 */
1305 	if (have_ripv1_out || have_ripv1_in) {
1306 		ifp->int_state |= IS_NEED_NET_SYN;
1307 		rt = rtget(ifp->int_std_addr, ifp->int_std_mask);
1308 		if (rt != 0
1309 		    && 0 == (rt->rt_state & RS_NO_NET_SYN)
1310 		    && (!(rt->rt_state & RS_NET_SYN)
1311 			|| rt->rt_metric > ifp->int_metric)) {
1312 			rtdelete(rt);
1313 			rt = 0;
1314 		}
1315 		if (rt == 0) {
1316 			new.rts_ifp = ifp;
1317 			new.rts_gate = ifp->int_addr;
1318 			new.rts_router = ifp->int_addr;
1319 			new.rts_metric = ifp->int_metric;
1320 			rtadd(ifp->int_std_addr, ifp->int_std_mask,
1321 			      RS_NET_SYN, &new);
1322 		}
1323 
1324 	} else {
1325 		ifp->int_state &= ~IS_NEED_NET_SYN;
1326 
1327 		rt = rtget(ifp->int_std_addr,
1328 			   ifp->int_std_mask);
1329 		if (rt != 0
1330 		    && (rt->rt_state & RS_NET_SYN)
1331 		    && rt->rt_ifp == ifp)
1332 			rtbad_sub(rt);
1333 	}
1334 }
1335 
1336 
1337 /* Add route for interface if not currently installed.
1338  * Create route to other end if a point-to-point link,
1339  * otherwise a route to this (sub)network.
1340  */
1341 int					/* 0=bad interface */
1342 addrouteforif(struct interface *ifp)
1343 {
1344 	struct rt_entry *rt;
1345 	static struct rt_spare new;
1346 	naddr dst;
1347 
1348 
1349 	/* skip sick interfaces
1350 	 */
1351 	if (ifp->int_state & IS_BROKE)
1352 		return 0;
1353 
1354 	/* If the interface on a subnet, then install a RIPv1 route to
1355 	 * the network as well (unless it is sick).
1356 	 */
1357 	if (ifp->int_state & IS_SUBNET)
1358 		check_net_syn(ifp);
1359 
1360 	dst = (0 != (ifp->int_if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK))
1361 	       ? ifp->int_dstaddr
1362 	       : htonl(ifp->int_net));
1363 
1364 	new.rts_ifp = ifp;
1365 	new.rts_router = ifp->int_addr;
1366 	new.rts_gate = ifp->int_addr;
1367 	new.rts_metric = ifp->int_metric;
1368 	new.rts_time = now.tv_sec;
1369 
1370 	/* If we are going to send packets to the gateway,
1371 	 * it must be reachable using our physical interfaces
1372 	 */
1373 	if ((ifp->int_state & IS_REMOTE)
1374 	    && !(ifp->int_state & IS_EXTERNAL)
1375 	    && !check_remote(ifp))
1376 		return 0;
1377 
1378 	/* We are finished if the correct main interface route exists.
1379 	 * The right route must be for the right interface, not synthesized
1380 	 * from a subnet, be a "gateway" or not as appropriate, and so forth.
1381 	 */
1382 	del_static(dst, ifp->int_mask, 0, 0);
1383 	rt = rtget(dst, ifp->int_mask);
1384 	if (rt != 0) {
1385 		if ((rt->rt_ifp != ifp
1386 		     || rt->rt_router != ifp->int_addr)
1387 		    && (!(ifp->int_state & IS_DUP)
1388 			|| rt->rt_ifp == 0
1389 			|| (rt->rt_ifp->int_state & IS_BROKE))) {
1390 			rtdelete(rt);
1391 			rt = 0;
1392 		} else {
1393 			rtchange(rt, ((rt->rt_state | RS_IF)
1394 				      & ~(RS_NET_SYN | RS_LOCAL)),
1395 				 &new, 0);
1396 		}
1397 	}
1398 	if (rt == 0) {
1399 		if (ifp->int_transitions++ > 0)
1400 			trace_act("re-install interface %s",
1401 				  ifp->int_name);
1402 
1403 		rtadd(dst, ifp->int_mask, RS_IF, &new);
1404 	}
1405 
1406 	return 1;
1407 }
1408