xref: /dragonfly/sbin/routed/if.c (revision c1543a89)
1 /*
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgment:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * $FreeBSD: src/sbin/routed/if.c,v 1.6.2.1 2000/08/14 17:00:03 sheldonh Exp $
34  * $DragonFly: src/sbin/routed/if.c,v 1.5 2005/03/16 21:21:34 cpressey Exp $
35  */
36 
37 #include "defs.h"
38 #include "pathnames.h"
39 
40 #if !defined(sgi) && !defined(__NetBSD__)
41 static char sccsid[] __attribute__((unused)) = "@(#)if.c	8.1 (Berkeley) 6/5/93";
42 #elif defined(__NetBSD__)
43 #include <sys/cdefs.h>
44 __RCSID("$NetBSD$");
45 #endif
46 
47 struct interface *ifnet;		/* all interfaces */
48 
49 /* hash table for all interfaces, big enough to tolerate ridiculous
50  * numbers of IP aliases.  Crazy numbers of aliases such as 7000
51  * still will not do well, but not just in looking up interfaces
52  * by name or address.
53  */
54 #define AHASH_LEN 211			/* must be prime */
55 #define AHASH(a) &ahash_tbl[(a)%AHASH_LEN]
56 struct interface *ahash_tbl[AHASH_LEN];
57 
58 #define BHASH_LEN 211			/* must be prime */
59 #define BHASH(a) &bhash_tbl[(a)%BHASH_LEN]
60 struct interface *bhash_tbl[BHASH_LEN];
61 
62 struct interface *remote_if;		/* remote interfaces */
63 
64 /* hash for physical interface names.
65  * Assume there are never more 100 or 200 real interfaces, and that
66  * aliases are put on the end of the hash chains.
67  */
68 #define NHASH_LEN 97
69 struct interface *nhash_tbl[NHASH_LEN];
70 
71 int	tot_interfaces;			/* # of remote and local interfaces */
72 int	rip_interfaces;			/* # of interfaces doing RIP */
73 int	foundloopback;			/* valid flag for loopaddr */
74 naddr	loopaddr;			/* our address on loopback */
75 struct	rt_spare loop_rts;
76 
77 struct timeval ifinit_timer;
78 static struct timeval last_ifinit;
79 #define IF_RESCAN_DELAY() (last_ifinit.tv_sec == now.tv_sec		\
80 			   && last_ifinit.tv_usec == now.tv_usec	\
81 			   && timercmp(&ifinit_timer, &now, >))
82 
83 int	have_ripv1_out;			/* have a RIPv1 interface */
84 int	have_ripv1_in;
85 
86 
87 static struct interface**
88 nhash(char *p)
89 {
90 	u_int i;
91 
92 	for (i = 0; *p != '\0'; p++) {
93 		i = ((i<<1) & 0x7fffffff) | ((i>>31) & 1);
94 		i ^= *p;
95 	}
96 	return &nhash_tbl[i % NHASH_LEN];
97 }
98 
99 
100 /* Link a new interface into the lists and hash tables.
101  */
102 void
103 if_link(struct interface *ifp)
104 {
105 	struct interface **hifp;
106 
107 	ifp->int_prev = &ifnet;
108 	ifp->int_next = ifnet;
109 	if (ifnet != 0)
110 		ifnet->int_prev = &ifp->int_next;
111 	ifnet = ifp;
112 
113 	hifp = AHASH(ifp->int_addr);
114 	ifp->int_ahash_prev = hifp;
115 	if ((ifp->int_ahash = *hifp) != 0)
116 		(*hifp)->int_ahash_prev = &ifp->int_ahash;
117 	*hifp = ifp;
118 
119 	if (ifp->int_if_flags & IFF_BROADCAST) {
120 		hifp = BHASH(ifp->int_brdaddr);
121 		ifp->int_bhash_prev = hifp;
122 		if ((ifp->int_bhash = *hifp) != 0)
123 			(*hifp)->int_bhash_prev = &ifp->int_bhash;
124 		*hifp = ifp;
125 	}
126 
127 	if (ifp->int_state & IS_REMOTE) {
128 		ifp->int_rlink_prev = &remote_if;
129 		ifp->int_rlink = remote_if;
130 		if (remote_if != 0)
131 			remote_if->int_rlink_prev = &ifp->int_rlink;
132 		remote_if = ifp;
133 	}
134 
135 	hifp = nhash(ifp->int_name);
136 	if (ifp->int_state & IS_ALIAS) {
137 		/* put aliases on the end of the hash chain */
138 		while (*hifp != 0)
139 			hifp = &(*hifp)->int_nhash;
140 	}
141 	ifp->int_nhash_prev = hifp;
142 	if ((ifp->int_nhash = *hifp) != 0)
143 		(*hifp)->int_nhash_prev = &ifp->int_nhash;
144 	*hifp = ifp;
145 }
146 
147 
148 /* Find the interface with an address
149  */
150 struct interface *
151 ifwithaddr(naddr addr,
152 	   int	bcast,			/* notice IFF_BROADCAST address */
153 	   int	remote)			/* include IS_REMOTE interfaces */
154 {
155 	struct interface *ifp, *possible = 0;
156 
157 	remote = (remote == 0) ? IS_REMOTE : 0;
158 
159 	for (ifp = *AHASH(addr); ifp; ifp = ifp->int_ahash) {
160 		if (ifp->int_addr != addr)
161 			continue;
162 		if ((ifp->int_state & remote) != 0)
163 			continue;
164 		if ((ifp->int_state & (IS_BROKE | IS_PASSIVE)) == 0)
165 			return ifp;
166 		possible = ifp;
167 	}
168 
169 	if (possible || !bcast)
170 		return possible;
171 
172 	for (ifp = *BHASH(addr); ifp; ifp = ifp->int_bhash) {
173 		if (ifp->int_brdaddr != addr)
174 			continue;
175 		if ((ifp->int_state & remote) != 0)
176 			continue;
177 		if ((ifp->int_state & (IS_BROKE | IS_PASSIVE)) == 0)
178 			return ifp;
179 		possible = ifp;
180 	}
181 
182 	return possible;
183 }
184 
185 
186 /* find the interface with a name
187  */
188 struct interface *
189 ifwithname(char *name,			/* "ec0" or whatever */
190 	   naddr addr)			/* 0 or network address */
191 {
192 	struct interface *ifp;
193 
194 	for (;;) {
195 		for (ifp = *nhash(name); ifp != 0; ifp = ifp->int_nhash) {
196 			/* If the network address is not specified,
197 			 * ignore any alias interfaces.  Otherwise, look
198 			 * for the interface with the target name and address.
199 			 */
200 			if (!strcmp(ifp->int_name, name)
201 			    && ((addr == 0 && !(ifp->int_state & IS_ALIAS))
202 				|| (ifp->int_addr == addr)))
203 				return ifp;
204 		}
205 
206 		/* If there is no known interface, maybe there is a
207 		 * new interface.  So just once look for new interfaces.
208 		 */
209 		if (IF_RESCAN_DELAY())
210 			return 0;
211 		ifinit();
212 	}
213 }
214 
215 
216 struct interface *
217 ifwithindex(u_short idx, 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 == idx)
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 
247 	maybe = 0;
248 	for (;;) {
249 		for (ifp = ifnet; ifp; ifp = ifp->int_next) {
250 			if (ifp->int_if_flags & IFF_POINTOPOINT) {
251 				/* finished with a match */
252 				if (ifp->int_dstaddr == addr)
253 					return ifp;
254 
255 			} else {
256 				/* finished with an exact match */
257 				if (ifp->int_addr == addr)
258 					return ifp;
259 
260 				/* Look for the longest approximate match.
261 				 */
262 				if (on_net(addr, ifp->int_net, ifp->int_mask)
263 				    && (maybe == 0
264 					|| ifp->int_mask > maybe->int_mask))
265 					maybe = ifp;
266 			}
267 		}
268 
269 		if (maybe != 0
270 		    || IF_RESCAN_DELAY())
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 	}
278 }
279 
280 
281 /* Return the classical netmask for an IP address.
282  */
283 naddr					/* host byte order */
284 std_mask(naddr addr)			/* network byte order */
285 {
286 	addr = ntohl(addr);		/* was a host, not a network */
287 
288 	if (addr == 0)			/* default route has mask 0 */
289 		return 0;
290 	if (IN_CLASSA(addr))
291 		return IN_CLASSA_NET;
292 	if (IN_CLASSB(addr))
293 		return IN_CLASSB_NET;
294 	return IN_CLASSC_NET;
295 }
296 
297 
298 /* Find the netmask that would be inferred by RIPv1 listeners
299  *	on the given interface for a given network.
300  *	If no interface is specified, look for the best fitting	interface.
301  */
302 naddr
303 ripv1_mask_net(naddr addr,		/* in network byte order */
304 	       struct interface *ifp)	/* as seen on this interface */
305 {
306 	struct r1net *r1p;
307 	naddr mask = 0;
308 
309 	if (addr == 0)			/* default always has 0 mask */
310 		return mask;
311 
312 	if (ifp != 0 && ifp->int_ripv1_mask != HOST_MASK) {
313 		/* If the target network is that of the associated interface
314 		 * on which it arrived, then use the netmask of the interface.
315 		 */
316 		if (on_net(addr, ifp->int_net, ifp->int_std_mask))
317 			mask = ifp->int_ripv1_mask;
318 
319 	} else {
320 		/* Examine all interfaces, and if it the target seems
321 		 * to have the same network number of an interface, use the
322 		 * netmask of that interface.  If there is more than one
323 		 * such interface, prefer the interface with the longest
324 		 * match.
325 		 */
326 		for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
327 			if (on_net(addr, ifp->int_std_net, ifp->int_std_mask)
328 			    && ifp->int_ripv1_mask > mask
329 			    && ifp->int_ripv1_mask != HOST_MASK)
330 				mask = ifp->int_ripv1_mask;
331 		}
332 
333 	}
334 
335 	/* check special definitions */
336 	if (mask == 0) {
337 		for (r1p = r1nets; r1p != 0; r1p = r1p->r1net_next) {
338 			if (on_net(addr, r1p->r1net_net, r1p->r1net_match)
339 			    && r1p->r1net_mask > mask)
340 				mask = r1p->r1net_mask;
341 		}
342 
343 		/* Otherwise, make the classic A/B/C guess.
344 		 */
345 		if (mask == 0)
346 			mask = std_mask(addr);
347 	}
348 
349 	return mask;
350 }
351 
352 
353 naddr
354 ripv1_mask_host(naddr addr,		/* in network byte order */
355 		struct interface *ifp)	/* as seen on this interface */
356 {
357 	naddr mask = ripv1_mask_net(addr, ifp);
358 
359 
360 	/* If the computed netmask does not mask the address,
361 	 * then assume it is a host address
362 	 */
363 	if ((ntohl(addr) & ~mask) != 0)
364 		mask = HOST_MASK;
365 	return mask;
366 }
367 
368 
369 /* See if a IP address looks reasonable as a destination
370  */
371 int					/* 0=bad */
372 check_dst(naddr addr)
373 {
374 	addr = ntohl(addr);
375 
376 	if (IN_CLASSA(addr)) {
377 		if (addr == 0)
378 			return 1;	/* default */
379 
380 		addr >>= IN_CLASSA_NSHIFT;
381 		return (addr != 0 && addr != IN_LOOPBACKNET);
382 	}
383 
384 	return (IN_CLASSB(addr) || IN_CLASSC(addr));
385 }
386 
387 
388 /* See a new interface duplicates an existing interface.
389  */
390 struct interface *
391 check_dup(naddr addr,			/* IP address, so network byte order */
392 	  naddr dstaddr,		/* ditto */
393 	  naddr mask,			/* mask, so host byte order */
394 	  int if_flags)
395 {
396 	struct interface *ifp;
397 
398 	for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next) {
399 		if (ifp->int_mask != mask)
400 			continue;
401 
402 		if (!iff_up(ifp->int_if_flags))
403 			continue;
404 
405 		/* The local address can only be shared with a point-to-point
406 		 * link.
407 		 */
408 		if (ifp->int_addr == addr
409 		    && (((if_flags|ifp->int_if_flags) & IFF_POINTOPOINT) == 0))
410 			return ifp;
411 
412 		if (on_net(ifp->int_dstaddr, ntohl(dstaddr),mask))
413 			return ifp;
414 	}
415 	return 0;
416 }
417 
418 
419 /* See that a remote gateway is reachable.
420  *	Note that the answer can change as real interfaces come and go.
421  */
422 int					/* 0=bad */
423 check_remote(struct interface *ifp)
424 {
425 	struct rt_entry *rt;
426 
427 	/* do not worry about other kinds */
428 	if (!(ifp->int_state & IS_REMOTE))
429 	    return 1;
430 
431 	rt = rtfind(ifp->int_addr);
432 	if (rt != 0
433 	    && rt->rt_ifp != 0
434 	    &&on_net(ifp->int_addr,
435 		     rt->rt_ifp->int_net, rt->rt_ifp->int_mask))
436 		return 1;
437 
438 	/* the gateway cannot be reached directly from one of our
439 	 * interfaces
440 	 */
441 	if (!(ifp->int_state & IS_BROKE)) {
442 		msglog("unreachable gateway %s in "_PATH_GATEWAYS,
443 		       naddr_ntoa(ifp->int_addr));
444 		if_bad(ifp);
445 	}
446 	return 0;
447 }
448 
449 
450 /* Delete an interface.
451  */
452 static void
453 ifdel(struct interface *ifp)
454 {
455 	struct ip_mreq m;
456 	struct interface *ifp1;
457 
458 
459 	trace_if("Del", ifp);
460 
461 	ifp->int_state |= IS_BROKE;
462 
463 	/* unlink the interface
464 	 */
465 	*ifp->int_prev = ifp->int_next;
466 	if (ifp->int_next != 0)
467 		ifp->int_next->int_prev = ifp->int_prev;
468 	*ifp->int_ahash_prev = ifp->int_ahash;
469 	if (ifp->int_ahash != 0)
470 		ifp->int_ahash->int_ahash_prev = ifp->int_ahash_prev;
471 	*ifp->int_nhash_prev = ifp->int_nhash;
472 	if (ifp->int_nhash != 0)
473 		ifp->int_nhash->int_nhash_prev = ifp->int_nhash_prev;
474 	if (ifp->int_if_flags & IFF_BROADCAST) {
475 		*ifp->int_bhash_prev = ifp->int_bhash;
476 		if (ifp->int_bhash != 0)
477 			ifp->int_bhash->int_bhash_prev = ifp->int_bhash_prev;
478 	}
479 	if (ifp->int_state & IS_REMOTE) {
480 		*ifp->int_rlink_prev = ifp->int_rlink;
481 		if (ifp->int_rlink != 0)
482 			ifp->int_rlink->int_rlink_prev = ifp->int_rlink_prev;
483 	}
484 
485 	if (!(ifp->int_state & IS_ALIAS)) {
486 		/* delete aliases when the main interface dies
487 		 */
488 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
489 			if (ifp1 != ifp
490 			    && !strcmp(ifp->int_name, ifp1->int_name))
491 				ifdel(ifp1);
492 		}
493 
494 		if ((ifp->int_if_flags & IFF_MULTICAST)
495 #ifdef MCAST_PPP_BUG
496 		    && !(ifp->int_if_flags & IFF_POINTOPOINT)
497 #endif
498 		    && rip_sock >= 0) {
499 			m.imr_multiaddr.s_addr = htonl(INADDR_RIP_GROUP);
500 			m.imr_interface.s_addr = ((ifp->int_if_flags
501 						   & IFF_POINTOPOINT)
502 						  ? ifp->int_dstaddr
503 						  : ifp->int_addr);
504 			if (setsockopt(rip_sock,IPPROTO_IP,IP_DROP_MEMBERSHIP,
505 				       &m, sizeof(m)) < 0
506 			    && errno != EADDRNOTAVAIL
507 			    && !TRACEACTIONS)
508 				LOGERR("setsockopt(IP_DROP_MEMBERSHIP RIP)");
509 			if (rip_sock_mcast == ifp)
510 				rip_sock_mcast = 0;
511 		}
512 		if (ifp->int_rip_sock >= 0) {
513 			close(ifp->int_rip_sock);
514 			ifp->int_rip_sock = -1;
515 			fix_select();
516 		}
517 
518 		tot_interfaces--;
519 		if (!IS_RIP_OFF(ifp->int_state))
520 			rip_interfaces--;
521 
522 		/* Zap all routes associated with this interface.
523 		 * Assume routes just using gateways beyond this interface
524 		 * will timeout naturally, and have probably already died.
525 		 */
526 		rn_walktree(rhead, walk_bad, 0);
527 
528 		set_rdisc_mg(ifp, 0);
529 		if_bad_rdisc(ifp);
530 	}
531 
532 	free(ifp);
533 }
534 
535 
536 /* Mark an interface ill.
537  */
538 void
539 if_sick(struct interface *ifp)
540 {
541 	if (0 == (ifp->int_state & (IS_SICK | IS_BROKE))) {
542 		ifp->int_state |= IS_SICK;
543 		ifp->int_act_time = NEVER;
544 		trace_if("Chg", ifp);
545 
546 		LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
547 	}
548 }
549 
550 
551 /* Mark an interface dead.
552  */
553 void
554 if_bad(struct interface *ifp)
555 {
556 	struct interface *ifp1;
557 
558 
559 	if (ifp->int_state & IS_BROKE)
560 		return;
561 
562 	LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
563 
564 	ifp->int_state |= (IS_BROKE | IS_SICK);
565 	ifp->int_act_time = NEVER;
566 	ifp->int_query_time = NEVER;
567 	ifp->int_data.ts = now.tv_sec;
568 
569 	trace_if("Chg", ifp);
570 
571 	if (!(ifp->int_state & IS_ALIAS)) {
572 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
573 			if (ifp1 != ifp
574 			    && !strcmp(ifp->int_name, ifp1->int_name))
575 				if_bad(ifp1);
576 		}
577 		rn_walktree(rhead, walk_bad, 0);
578 		if_bad_rdisc(ifp);
579 	}
580 }
581 
582 
583 /* Mark an interface alive
584  */
585 int					/* 1=it was dead */
586 if_ok(struct interface *ifp,
587       const char *type)
588 {
589 	struct interface *ifp1;
590 
591 
592 	if (!(ifp->int_state & IS_BROKE)) {
593 		if (ifp->int_state & IS_SICK) {
594 			trace_act("%sinterface %s to %s working better",
595 				  type,
596 				  ifp->int_name, naddr_ntoa(ifp->int_dstaddr));
597 			ifp->int_state &= ~IS_SICK;
598 		}
599 		return 0;
600 	}
601 
602 	msglog("%sinterface %s to %s restored",
603 	       type, ifp->int_name, naddr_ntoa(ifp->int_dstaddr));
604 	ifp->int_state &= ~(IS_BROKE | IS_SICK);
605 	ifp->int_data.ts = 0;
606 
607 	if (!(ifp->int_state & IS_ALIAS)) {
608 		for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
609 			if (ifp1 != ifp
610 			    && !strcmp(ifp->int_name, ifp1->int_name))
611 				if_ok(ifp1, type);
612 		}
613 		if_ok_rdisc(ifp);
614 	}
615 
616 	if (ifp->int_state & IS_REMOTE) {
617 		if (!addrouteforif(ifp))
618 			return 0;
619 	}
620 	return 1;
621 }
622 
623 
624 /* disassemble routing message
625  */
626 void
627 rt_xaddrs(struct rt_addrinfo *info,
628 	  struct sockaddr *sa,
629 	  struct sockaddr *lim,
630 	  int addrs)
631 {
632 	int i;
633 #ifdef _HAVE_SA_LEN
634 	static struct sockaddr sa_zero;
635 #endif
636 #ifdef sgi
637 #define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(__uint64_t) - 1))) \
638 		    : sizeof(__uint64_t))
639 #else
640 #define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) \
641 		    : sizeof(long))
642 #endif
643 
644 
645 	memset(info, 0, sizeof(*info));
646 	info->rti_addrs = addrs;
647 	for (i = 0; i < RTAX_MAX && sa < lim; i++) {
648 		if ((addrs & (1 << i)) == 0)
649 			continue;
650 #ifdef _HAVE_SA_LEN
651 		info->rti_info[i] = (sa->sa_len != 0) ? sa : &sa_zero;
652 		sa = (struct sockaddr *)((char*)(sa)
653 					 + ROUNDUP(sa->sa_len));
654 #else
655 		info->rti_info[i] = sa;
656 		sa = (struct sockaddr *)((char*)(sa)
657 					 + ROUNDUP(_FAKE_SA_LEN_DST(sa)));
658 #endif
659 	}
660 }
661 
662 
663 /* Find the network interfaces which have configured themselves.
664  *	This must be done regularly, if only for extra addresses
665  *	that come and go on interfaces.
666  */
667 void
668 ifinit(void)
669 {
670 	static char *sysctl_buf;
671 	static size_t sysctl_buf_size = 0;
672 	uint complaints = 0;
673 	static u_int prev_complaints = 0;
674 #	define COMP_NOT_INET	0x001
675 #	define COMP_NOADDR	0x002
676 #	define COMP_BADADDR	0x004
677 #	define COMP_NODST	0x008
678 #	define COMP_NOBADR	0x010
679 #	define COMP_NOMASK	0x020
680 #	define COMP_DUP		0x040
681 #	define COMP_BAD_METRIC	0x080
682 #	define COMP_NETMASK	0x100
683 
684 	struct interface ifs, ifs0, *ifp, *ifp1;
685 	struct rt_entry *rt;
686 	size_t needed;
687 	int mib[6];
688 	struct if_msghdr *ifm;
689 	struct ifa_msghdr *ifam, *ifam_lim, *ifam2;
690 	int in, ierr, out, oerr;
691 	struct intnet *intnetp;
692 	struct rt_addrinfo info;
693 #ifdef SIOCGIFMETRIC
694 	struct ifreq ifr;
695 #endif
696 
697 
698 	last_ifinit = now;
699 	ifinit_timer.tv_sec = now.tv_sec + (supplier
700 					    ? CHECK_ACT_INTERVAL
701 					    : CHECK_QUIET_INTERVAL);
702 
703 	/* mark all interfaces so we can get rid of those that disappear */
704 	for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next)
705 		ifp->int_state &= ~(IS_CHECKED | IS_DUP);
706 
707 	/* Fetch the interface list, without too many system calls
708 	 * since we do it repeatedly.
709 	 */
710 	mib[0] = CTL_NET;
711 	mib[1] = PF_ROUTE;
712 	mib[2] = 0;
713 	mib[3] = AF_INET;
714 	mib[4] = NET_RT_IFLIST;
715 	mib[5] = 0;
716 	for (;;) {
717 		if ((needed = sysctl_buf_size) != 0) {
718 			if (sysctl(mib, 6, sysctl_buf,&needed, 0, 0) >= 0)
719 				break;
720 			/* retry if the table grew */
721 			if (errno != ENOMEM && errno != EFAULT)
722 				BADERR(1, "ifinit: sysctl(RT_IFLIST)");
723 			free(sysctl_buf);
724 			needed = 0;
725 		}
726 		if (sysctl(mib, 6, 0, &needed, 0, 0) < 0)
727 			BADERR(1,"ifinit: sysctl(RT_IFLIST) estimate");
728 		sysctl_buf = rtmalloc(sysctl_buf_size = needed,
729 				      "ifinit sysctl");
730 	}
731 
732 	ifam_lim = (struct ifa_msghdr *)(sysctl_buf + needed);
733 	for (ifam = (struct ifa_msghdr *)sysctl_buf;
734 	     ifam < ifam_lim;
735 	     ifam = ifam2) {
736 
737 		ifam2 = (struct ifa_msghdr*)((char*)ifam + ifam->ifam_msglen);
738 
739 		if (ifam->ifam_type == RTM_IFINFO) {
740 			struct sockaddr_dl *sdl;
741 
742 			ifm = (struct if_msghdr *)ifam;
743 			/* make prototype structure for the IP aliases
744 			 */
745 			memset(&ifs0, 0, sizeof(ifs0));
746 			ifs0.int_rip_sock = -1;
747 			ifs0.int_index = ifm->ifm_index;
748 			ifs0.int_if_flags = ifm->ifm_flags;
749 			ifs0.int_state = IS_CHECKED;
750 			ifs0.int_query_time = NEVER;
751 			ifs0.int_act_time = now.tv_sec;
752 			ifs0.int_data.ts = now.tv_sec;
753 			ifs0.int_data.ipackets = ifm->ifm_data.ifi_ipackets;
754 			ifs0.int_data.ierrors = ifm->ifm_data.ifi_ierrors;
755 			ifs0.int_data.opackets = ifm->ifm_data.ifi_opackets;
756 			ifs0.int_data.oerrors = ifm->ifm_data.ifi_oerrors;
757 #ifdef sgi
758 			ifs0.int_data.odrops = ifm->ifm_data.ifi_odrops;
759 #endif
760 			sdl = (struct sockaddr_dl *)(ifm + 1);
761 			sdl->sdl_data[sdl->sdl_nlen] = 0;
762 			strncpy(ifs0.int_name, sdl->sdl_data,
763 				MIN(sizeof(ifs0.int_name), sdl->sdl_nlen));
764 			continue;
765 		}
766 		if (ifam->ifam_type != RTM_NEWADDR) {
767 			logbad(1,"ifinit: out of sync");
768 			continue;
769 		}
770 		rt_xaddrs(&info, (struct sockaddr *)(ifam+1),
771 			  (struct sockaddr *)ifam2,
772 			  ifam->ifam_addrs);
773 
774 		/* Prepare for the next address of this interface, which
775 		 * will be an alias.
776 		 * Do not output RIP or Router-Discovery packets via aliases.
777 		 */
778 		memcpy(&ifs, &ifs0, sizeof(ifs));
779 		ifs0.int_state |= (IS_ALIAS | IS_NO_RIP_OUT | IS_NO_RDISC);
780 
781 		if (INFO_IFA(&info) == 0) {
782 			if (iff_up(ifs.int_if_flags)) {
783 				if (!(prev_complaints & COMP_NOADDR))
784 					msglog("%s has no address",
785 					       ifs.int_name);
786 				complaints |= COMP_NOADDR;
787 			}
788 			continue;
789 		}
790 		if (INFO_IFA(&info)->sa_family != AF_INET) {
791 			if (iff_up(ifs.int_if_flags)) {
792 				if (!(prev_complaints & COMP_NOT_INET))
793 					trace_act("%s: not AF_INET",
794 						  ifs.int_name);
795 				complaints |= COMP_NOT_INET;
796 			}
797 			continue;
798 		}
799 
800 		ifs.int_addr = S_ADDR(INFO_IFA(&info));
801 
802 		if (ntohl(ifs.int_addr)>>24 == 0
803 		    || ntohl(ifs.int_addr)>>24 == 0xff) {
804 			if (iff_up(ifs.int_if_flags)) {
805 				if (!(prev_complaints & COMP_BADADDR))
806 					msglog("%s has a bad address",
807 					       ifs.int_name);
808 				complaints |= COMP_BADADDR;
809 			}
810 			continue;
811 		}
812 
813 		if (ifs.int_if_flags & IFF_LOOPBACK) {
814 			ifs.int_state |= IS_PASSIVE | IS_NO_RIP | IS_NO_RDISC;
815 			ifs.int_dstaddr = ifs.int_addr;
816 			ifs.int_mask = HOST_MASK;
817 			ifs.int_ripv1_mask = HOST_MASK;
818 			ifs.int_std_mask = std_mask(ifs.int_dstaddr);
819 			ifs.int_net = ntohl(ifs.int_dstaddr);
820 			if (!foundloopback) {
821 				foundloopback = 1;
822 				loopaddr = ifs.int_addr;
823 				loop_rts.rts_gate = loopaddr;
824 				loop_rts.rts_router = loopaddr;
825 			}
826 
827 		} else if (ifs.int_if_flags & IFF_POINTOPOINT) {
828 			if (INFO_BRD(&info) == 0
829 			    || INFO_BRD(&info)->sa_family != AF_INET) {
830 				if (iff_up(ifs.int_if_flags)) {
831 					if (!(prev_complaints & COMP_NODST))
832 						msglog("%s has a bad"
833 						       " destination address",
834 						       ifs.int_name);
835 					complaints |= COMP_NODST;
836 				}
837 				continue;
838 			}
839 			ifs.int_dstaddr = S_ADDR(INFO_BRD(&info));
840 			if (ntohl(ifs.int_dstaddr)>>24 == 0
841 			    || ntohl(ifs.int_dstaddr)>>24 == 0xff) {
842 				if (iff_up(ifs.int_if_flags)) {
843 					if (!(prev_complaints & COMP_NODST))
844 						msglog("%s has a bad"
845 						       " destination address",
846 						       ifs.int_name);
847 					complaints |= COMP_NODST;
848 				}
849 				continue;
850 			}
851 			ifs.int_mask = HOST_MASK;
852 			ifs.int_ripv1_mask = ntohl(S_ADDR(INFO_MASK(&info)));
853 			ifs.int_std_mask = std_mask(ifs.int_dstaddr);
854 			ifs.int_net = ntohl(ifs.int_dstaddr);
855 
856 		}  else {
857 			if (INFO_MASK(&info) == 0) {
858 				if (iff_up(ifs.int_if_flags)) {
859 					if (!(prev_complaints & COMP_NOMASK))
860 						msglog("%s has no netmask",
861 						       ifs.int_name);
862 					complaints |= COMP_NOMASK;
863 				}
864 				continue;
865 			}
866 			ifs.int_dstaddr = ifs.int_addr;
867 			ifs.int_mask = ntohl(S_ADDR(INFO_MASK(&info)));
868 			ifs.int_ripv1_mask = ifs.int_mask;
869 			ifs.int_std_mask = std_mask(ifs.int_addr);
870 			ifs.int_net = ntohl(ifs.int_addr) & ifs.int_mask;
871 			if (ifs.int_mask != ifs.int_std_mask)
872 				ifs.int_state |= IS_SUBNET;
873 
874 			if (ifs.int_if_flags & IFF_BROADCAST) {
875 				if (INFO_BRD(&info) == 0) {
876 					if (iff_up(ifs.int_if_flags)) {
877 					    if (!(prev_complaints
878 						  & COMP_NOBADR))
879 						msglog("%s has"
880 						       "no broadcast address",
881 						       ifs.int_name);
882 					    complaints |= COMP_NOBADR;
883 					}
884 					continue;
885 				}
886 				ifs.int_brdaddr = S_ADDR(INFO_BRD(&info));
887 			}
888 		}
889 		ifs.int_std_net = ifs.int_net & ifs.int_std_mask;
890 		ifs.int_std_addr = htonl(ifs.int_std_net);
891 
892 		/* Use a minimum metric of one.  Treat the interface metric
893 		 * (default 0) as an increment to the hop count of one.
894 		 *
895 		 * The metric obtained from the routing socket dump of
896 		 * interface addresses is wrong.  It is not set by the
897 		 * SIOCSIFMETRIC ioctl.
898 		 */
899 #ifdef SIOCGIFMETRIC
900 		strncpy(ifr.ifr_name, ifs.int_name, sizeof(ifr.ifr_name));
901 		if (ioctl(rt_sock, SIOCGIFMETRIC, &ifr) < 0) {
902 			DBGERR(1, "ioctl(SIOCGIFMETRIC)");
903 			ifs.int_metric = 0;
904 		} else {
905 			ifs.int_metric = ifr.ifr_metric;
906 		}
907 #else
908 		ifs.int_metric = ifam->ifam_metric;
909 #endif
910 		if (ifs.int_metric > HOPCNT_INFINITY) {
911 			ifs.int_metric = 0;
912 			if (!(prev_complaints & COMP_BAD_METRIC)
913 			    && iff_up(ifs.int_if_flags)) {
914 				complaints |= COMP_BAD_METRIC;
915 				msglog("%s has a metric of %d",
916 				       ifs.int_name, ifs.int_metric);
917 			}
918 		}
919 
920 		/* See if this is a familiar interface.
921 		 * If so, stop worrying about it if it is the same.
922 		 * Start it over if it now is to somewhere else, as happens
923 		 * frequently with PPP and SLIP.
924 		 */
925 		ifp = ifwithname(ifs.int_name, ((ifs.int_state & IS_ALIAS)
926 						? ifs.int_addr
927 						: 0));
928 		if (ifp != 0) {
929 			ifp->int_state |= IS_CHECKED;
930 
931 			if (0 != ((ifp->int_if_flags ^ ifs.int_if_flags)
932 				  & (IFF_BROADCAST
933 				     | IFF_LOOPBACK
934 				     | IFF_POINTOPOINT
935 				     | IFF_MULTICAST))
936 			    || 0 != ((ifp->int_state ^ ifs.int_state)
937 				     & IS_ALIAS)
938 			    || ifp->int_addr != ifs.int_addr
939 			    || ifp->int_brdaddr != ifs.int_brdaddr
940 			    || ifp->int_dstaddr != ifs.int_dstaddr
941 			    || ifp->int_mask != ifs.int_mask
942 			    || ifp->int_metric != ifs.int_metric) {
943 				/* Forget old information about
944 				 * a changed interface.
945 				 */
946 				trace_act("interface %s has changed",
947 					  ifp->int_name);
948 				ifdel(ifp);
949 				ifp = 0;
950 			}
951 		}
952 
953 		if (ifp != 0) {
954 			/* The primary representative of an alias worries
955 			 * about how things are working.
956 			 */
957 			if (ifp->int_state & IS_ALIAS)
958 				continue;
959 
960 			/* note interfaces that have been turned off
961 			 */
962 			if (!iff_up(ifs.int_if_flags)) {
963 				if (iff_up(ifp->int_if_flags)) {
964 					msglog("interface %s to %s turned off",
965 					       ifp->int_name,
966 					       naddr_ntoa(ifp->int_dstaddr));
967 					if_bad(ifp);
968 					ifp->int_if_flags &= ~IFF_UP;
969 				} else if (now.tv_sec>(ifp->int_data.ts
970 						       + CHECK_BAD_INTERVAL)) {
971 					trace_act("interface %s has been off"
972 						  " %ld seconds; forget it",
973 						  ifp->int_name,
974 						  now.tv_sec-ifp->int_data.ts);
975 					ifdel(ifp);
976 				}
977 				continue;
978 			}
979 			/* or that were off and are now ok */
980 			if (!iff_up(ifp->int_if_flags)) {
981 				ifp->int_if_flags |= IFF_UP;
982 				if_ok(ifp, "");
983 			}
984 
985 			/* If it has been long enough,
986 			 * see if the interface is broken.
987 			 */
988 			if (now.tv_sec < ifp->int_data.ts+CHECK_BAD_INTERVAL)
989 				continue;
990 
991 			in = ifs.int_data.ipackets - ifp->int_data.ipackets;
992 			ierr = ifs.int_data.ierrors - ifp->int_data.ierrors;
993 			out = ifs.int_data.opackets - ifp->int_data.opackets;
994 			oerr = ifs.int_data.oerrors - ifp->int_data.oerrors;
995 #ifdef sgi
996 			/* Through at least IRIX 6.2, PPP and SLIP
997 			 * count packets dropped by the filters.
998 			 * But FDDI rings stuck non-operational count
999 			 * dropped packets as they wait for improvement.
1000 			 */
1001 			if (!(ifp->int_if_flags & IFF_POINTOPOINT))
1002 				oerr += (ifs.int_data.odrops
1003 					 - ifp->int_data.odrops);
1004 #endif
1005 			/* If the interface just awoke, restart the counters.
1006 			 */
1007 			if (ifp->int_data.ts == 0) {
1008 				ifp->int_data = ifs.int_data;
1009 				continue;
1010 			}
1011 			ifp->int_data = ifs.int_data;
1012 
1013 			/* Withhold judgment when the short error
1014 			 * counters wrap or the interface is reset.
1015 			 */
1016 			if (ierr < 0 || in < 0 || oerr < 0 || out < 0) {
1017 				LIM_SEC(ifinit_timer,
1018 					now.tv_sec+CHECK_BAD_INTERVAL);
1019 				continue;
1020 			}
1021 
1022 			/* Withhold judgement when there is no traffic
1023 			 */
1024 			if (in == 0 && out == 0 && ierr == 0 && oerr == 0)
1025 				continue;
1026 
1027 			/* It is bad if input or output is not working.
1028 			 * Require presistent problems before marking it dead.
1029 			 */
1030 			if ((in <= ierr && ierr > 0)
1031 			    || (out <= oerr && oerr > 0)) {
1032 				if (!(ifp->int_state & IS_SICK)) {
1033 					trace_act("interface %s to %s"
1034 						  " sick: in=%d ierr=%d"
1035 						  " out=%d oerr=%d",
1036 						  ifp->int_name,
1037 						  naddr_ntoa(ifp->int_dstaddr),
1038 						  in, ierr, out, oerr);
1039 					if_sick(ifp);
1040 					continue;
1041 				}
1042 				if (!(ifp->int_state & IS_BROKE)) {
1043 					msglog("interface %s to %s broken:"
1044 					       " in=%d ierr=%d out=%d oerr=%d",
1045 					       ifp->int_name,
1046 					       naddr_ntoa(ifp->int_dstaddr),
1047 					       in, ierr, out, oerr);
1048 					if_bad(ifp);
1049 				}
1050 				continue;
1051 			}
1052 
1053 			/* otherwise, it is active and healthy
1054 			 */
1055 			ifp->int_act_time = now.tv_sec;
1056 			if_ok(ifp, "");
1057 			continue;
1058 		}
1059 
1060 		/* This is a new interface.
1061 		 * If it is dead, forget it.
1062 		 */
1063 		if (!iff_up(ifs.int_if_flags))
1064 			continue;
1065 
1066 		/* If it duplicates an existing interface,
1067 		 * complain about it, mark the other one
1068 		 * duplicated, and forget this one.
1069 		 */
1070 		ifp = check_dup(ifs.int_addr,ifs.int_dstaddr,ifs.int_mask,
1071 				ifs.int_if_flags);
1072 		if (ifp != 0) {
1073 			/* Ignore duplicates of itself, caused by having
1074 			 * IP aliases on the same network.
1075 			 */
1076 			if (!strcmp(ifp->int_name, ifs.int_name))
1077 				continue;
1078 
1079 			if (!(prev_complaints & COMP_DUP)) {
1080 				complaints |= COMP_DUP;
1081 				msglog("%s (%s%s%s) is duplicated by"
1082 				       " %s (%s%s%s)",
1083 				       ifs.int_name,
1084 				       addrname(ifs.int_addr,ifs.int_mask,1),
1085 				       ((ifs.int_if_flags & IFF_POINTOPOINT)
1086 					? "-->" : ""),
1087 				       ((ifs.int_if_flags & IFF_POINTOPOINT)
1088 					? naddr_ntoa(ifs.int_dstaddr) : ""),
1089 				       ifp->int_name,
1090 				       addrname(ifp->int_addr,ifp->int_mask,1),
1091 				       ((ifp->int_if_flags & IFF_POINTOPOINT)
1092 					? "-->" : ""),
1093 				       ((ifp->int_if_flags & IFF_POINTOPOINT)
1094 					? naddr_ntoa(ifp->int_dstaddr) : ""));
1095 			}
1096 			ifp->int_state |= IS_DUP;
1097 			continue;
1098 		}
1099 
1100 		if (0 == (ifs.int_if_flags & (IFF_POINTOPOINT | IFF_BROADCAST))
1101 		    && !(ifs.int_state & IS_PASSIVE)) {
1102 			trace_act("%s is neither broadcast, point-to-point,"
1103 				  " nor loopback",
1104 				  ifs.int_name);
1105 			if (!(ifs.int_state & IFF_MULTICAST))
1106 				ifs.int_state |= IS_NO_RDISC;
1107 		}
1108 
1109 
1110 		/* It is new and ok.   Add it to the list of interfaces
1111 		 */
1112 		ifp = (struct interface *)rtmalloc(sizeof(*ifp), "ifinit ifp");
1113 		memcpy(ifp, &ifs, sizeof(*ifp));
1114 		get_parms(ifp);
1115 		if_link(ifp);
1116 		trace_if("Add", ifp);
1117 
1118 		/* Notice likely bad netmask.
1119 		 */
1120 		if (!(prev_complaints & COMP_NETMASK)
1121 		    && !(ifp->int_if_flags & IFF_POINTOPOINT)
1122 		    && ifp->int_addr != RIP_DEFAULT) {
1123 			for (ifp1 = ifnet; 0 != ifp1; ifp1 = ifp1->int_next) {
1124 				if (ifp1->int_mask == ifp->int_mask)
1125 					continue;
1126 				if (ifp1->int_if_flags & IFF_POINTOPOINT)
1127 					continue;
1128 				if (ifp1->int_dstaddr == RIP_DEFAULT)
1129 					continue;
1130 				/* ignore aliases on the right network */
1131 				if (!strcmp(ifp->int_name, ifp1->int_name))
1132 					continue;
1133 				if (on_net(ifp->int_dstaddr,
1134 					   ifp1->int_net, ifp1->int_mask)
1135 				    || on_net(ifp1->int_dstaddr,
1136 					      ifp->int_net, ifp->int_mask)) {
1137 					msglog("possible netmask problem"
1138 					       " between %s:%s and %s:%s",
1139 					       ifp->int_name,
1140 					       addrname(htonl(ifp->int_net),
1141 							ifp->int_mask, 1),
1142 					       ifp1->int_name,
1143 					       addrname(htonl(ifp1->int_net),
1144 							ifp1->int_mask, 1));
1145 					complaints |= COMP_NETMASK;
1146 				}
1147 			}
1148 		}
1149 
1150 		if (!(ifp->int_state & IS_ALIAS)) {
1151 			/* Count the # of directly connected networks.
1152 			 */
1153 			if (!(ifp->int_if_flags & IFF_LOOPBACK))
1154 				tot_interfaces++;
1155 			if (!IS_RIP_OFF(ifp->int_state))
1156 				rip_interfaces++;
1157 
1158 			/* turn on router discovery and RIP If needed */
1159 			if_ok_rdisc(ifp);
1160 			rip_on(ifp);
1161 		}
1162 	}
1163 
1164 	/* If we are multi-homed and have at least two interfaces
1165 	 * listening to RIP, then output by default.
1166 	 */
1167 	if (!supplier_set && rip_interfaces > 1)
1168 		set_supplier();
1169 
1170 	/* If we are multi-homed, optionally advertise a route to
1171 	 * our main address.
1172 	 */
1173 	if (advertise_mhome
1174 	    || (tot_interfaces > 1
1175 		&& mhome
1176 		&& (ifp = ifwithaddr(myaddr, 0, 0)) != 0
1177 		&& foundloopback)) {
1178 		advertise_mhome = 1;
1179 		rt = rtget(myaddr, HOST_MASK);
1180 		if (rt != 0) {
1181 			if (rt->rt_ifp != ifp
1182 			    || rt->rt_router != loopaddr) {
1183 				rtdelete(rt);
1184 				rt = 0;
1185 			} else {
1186 				loop_rts.rts_ifp = ifp;
1187 				loop_rts.rts_metric = 0;
1188 				loop_rts.rts_time = rt->rt_time;
1189 				rtchange(rt, rt->rt_state | RS_MHOME,
1190 					 &loop_rts, 0);
1191 			}
1192 		}
1193 		if (rt == 0) {
1194 			loop_rts.rts_ifp = ifp;
1195 			loop_rts.rts_metric = 0;
1196 			rtadd(myaddr, HOST_MASK, RS_MHOME, &loop_rts);
1197 		}
1198 	}
1199 
1200 	for (ifp = ifnet; ifp != 0; ifp = ifp1) {
1201 		ifp1 = ifp->int_next;	/* because we may delete it */
1202 
1203 		/* Forget any interfaces that have disappeared.
1204 		 */
1205 		if (!(ifp->int_state & (IS_CHECKED | IS_REMOTE))) {
1206 			trace_act("interface %s has disappeared",
1207 				  ifp->int_name);
1208 			ifdel(ifp);
1209 			continue;
1210 		}
1211 
1212 		if ((ifp->int_state & IS_BROKE)
1213 		    && !(ifp->int_state & IS_PASSIVE))
1214 			LIM_SEC(ifinit_timer, now.tv_sec+CHECK_BAD_INTERVAL);
1215 
1216 		/* If we ever have a RIPv1 interface, assume we always will.
1217 		 * It might come back if it ever goes away.
1218 		 */
1219 		if (!(ifp->int_state & IS_NO_RIPV1_OUT) && supplier)
1220 			have_ripv1_out = 1;
1221 		if (!(ifp->int_state & IS_NO_RIPV1_IN))
1222 			have_ripv1_in = 1;
1223 	}
1224 
1225 	for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
1226 		/* Ensure there is always a network route for interfaces,
1227 		 * after any dead interfaces have been deleted, which
1228 		 * might affect routes for point-to-point links.
1229 		 */
1230 		if (!addrouteforif(ifp))
1231 			continue;
1232 
1233 		/* Add routes to the local end of point-to-point interfaces
1234 		 * using loopback.
1235 		 */
1236 		if ((ifp->int_if_flags & IFF_POINTOPOINT)
1237 		    && !(ifp->int_state & IS_REMOTE)
1238 		    && foundloopback) {
1239 			/* Delete any routes to the network address through
1240 			 * foreign routers. Remove even static routes.
1241 			 */
1242 			del_static(ifp->int_addr, HOST_MASK, 0, 0);
1243 			rt = rtget(ifp->int_addr, HOST_MASK);
1244 			if (rt != 0 && rt->rt_router != loopaddr) {
1245 				rtdelete(rt);
1246 				rt = 0;
1247 			}
1248 			if (rt != 0) {
1249 				if (!(rt->rt_state & RS_LOCAL)
1250 				    || rt->rt_metric > ifp->int_metric) {
1251 					ifp1 = ifp;
1252 				} else {
1253 					ifp1 = rt->rt_ifp;
1254 				}
1255 				loop_rts.rts_ifp = ifp1;
1256 				loop_rts.rts_metric = 0;
1257 				loop_rts.rts_time = rt->rt_time;
1258 				rtchange(rt, ((rt->rt_state & ~RS_NET_SYN)
1259 					      | (RS_IF|RS_LOCAL)),
1260 					 &loop_rts, 0);
1261 			} else {
1262 				loop_rts.rts_ifp = ifp;
1263 				loop_rts.rts_metric = 0;
1264 				rtadd(ifp->int_addr, HOST_MASK,
1265 				      (RS_IF | RS_LOCAL), &loop_rts);
1266 			}
1267 		}
1268 	}
1269 
1270 	/* add the authority routes */
1271 	for (intnetp = intnets; intnetp!=0; intnetp = intnetp->intnet_next) {
1272 		rt = rtget(intnetp->intnet_addr, intnetp->intnet_mask);
1273 		if (rt != 0
1274 		    && !(rt->rt_state & RS_NO_NET_SYN)
1275 		    && !(rt->rt_state & RS_NET_INT)) {
1276 			rtdelete(rt);
1277 			rt = 0;
1278 		}
1279 		if (rt == 0) {
1280 			loop_rts.rts_ifp = 0;
1281 			loop_rts.rts_metric = intnetp->intnet_metric-1;
1282 			rtadd(intnetp->intnet_addr, intnetp->intnet_mask,
1283 			      RS_NET_SYN | RS_NET_INT, &loop_rts);
1284 		}
1285 	}
1286 
1287 	prev_complaints = complaints;
1288 }
1289 
1290 
1291 static void
1292 check_net_syn(struct interface *ifp)
1293 {
1294 	struct rt_entry *rt;
1295 	static struct rt_spare new;
1296 
1297 
1298 	/* Turn on the need to automatically synthesize a network route
1299 	 * for this interface only if we are running RIPv1 on some other
1300 	 * interface that is on a different class-A,B,or C network.
1301 	 */
1302 	if (have_ripv1_out || have_ripv1_in) {
1303 		ifp->int_state |= IS_NEED_NET_SYN;
1304 		rt = rtget(ifp->int_std_addr, ifp->int_std_mask);
1305 		if (rt != 0
1306 		    && 0 == (rt->rt_state & RS_NO_NET_SYN)
1307 		    && (!(rt->rt_state & RS_NET_SYN)
1308 			|| rt->rt_metric > ifp->int_metric)) {
1309 			rtdelete(rt);
1310 			rt = 0;
1311 		}
1312 		if (rt == 0) {
1313 			new.rts_ifp = ifp;
1314 			new.rts_gate = ifp->int_addr;
1315 			new.rts_router = ifp->int_addr;
1316 			new.rts_metric = ifp->int_metric;
1317 			rtadd(ifp->int_std_addr, ifp->int_std_mask,
1318 			      RS_NET_SYN, &new);
1319 		}
1320 
1321 	} else {
1322 		ifp->int_state &= ~IS_NEED_NET_SYN;
1323 
1324 		rt = rtget(ifp->int_std_addr,
1325 			   ifp->int_std_mask);
1326 		if (rt != 0
1327 		    && (rt->rt_state & RS_NET_SYN)
1328 		    && rt->rt_ifp == ifp)
1329 			rtbad_sub(rt);
1330 	}
1331 }
1332 
1333 
1334 /* Add route for interface if not currently installed.
1335  * Create route to other end if a point-to-point link,
1336  * otherwise a route to this (sub)network.
1337  */
1338 int					/* 0=bad interface */
1339 addrouteforif(struct interface *ifp)
1340 {
1341 	struct rt_entry *rt;
1342 	static struct rt_spare new;
1343 	naddr dst;
1344 
1345 
1346 	/* skip sick interfaces
1347 	 */
1348 	if (ifp->int_state & IS_BROKE)
1349 		return 0;
1350 
1351 	/* If the interface on a subnet, then install a RIPv1 route to
1352 	 * the network as well (unless it is sick).
1353 	 */
1354 	if (ifp->int_state & IS_SUBNET)
1355 		check_net_syn(ifp);
1356 
1357 	dst = (0 != (ifp->int_if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK))
1358 	       ? ifp->int_dstaddr
1359 	       : htonl(ifp->int_net));
1360 
1361 	new.rts_ifp = ifp;
1362 	new.rts_router = ifp->int_addr;
1363 	new.rts_gate = ifp->int_addr;
1364 	new.rts_metric = ifp->int_metric;
1365 	new.rts_time = now.tv_sec;
1366 
1367 	/* If we are going to send packets to the gateway,
1368 	 * it must be reachable using our physical interfaces
1369 	 */
1370 	if ((ifp->int_state & IS_REMOTE)
1371 	    && !(ifp->int_state & IS_EXTERNAL)
1372 	    && !check_remote(ifp))
1373 		return 0;
1374 
1375 	/* We are finished if the correct main interface route exists.
1376 	 * The right route must be for the right interface, not synthesized
1377 	 * from a subnet, be a "gateway" or not as appropriate, and so forth.
1378 	 */
1379 	del_static(dst, ifp->int_mask, 0, 0);
1380 	rt = rtget(dst, ifp->int_mask);
1381 	if (rt != 0) {
1382 		if ((rt->rt_ifp != ifp
1383 		     || rt->rt_router != ifp->int_addr)
1384 		    && (!(ifp->int_state & IS_DUP)
1385 			|| rt->rt_ifp == 0
1386 			|| (rt->rt_ifp->int_state & IS_BROKE))) {
1387 			rtdelete(rt);
1388 			rt = 0;
1389 		} else {
1390 			rtchange(rt, ((rt->rt_state | RS_IF)
1391 				      & ~(RS_NET_SYN | RS_LOCAL)),
1392 				 &new, 0);
1393 		}
1394 	}
1395 	if (rt == 0) {
1396 		if (ifp->int_transitions++ > 0)
1397 			trace_act("re-install interface %s",
1398 				  ifp->int_name);
1399 
1400 		rtadd(dst, ifp->int_mask, RS_IF, &new);
1401 	}
1402 
1403 	return 1;
1404 }
1405