xref: /netbsd-src/sys/netinet/if_arp.c (revision 001c68bd94f75ce9270b69227c4199fbf34ee396)
1 /*	$NetBSD: if_arp.c,v 1.92 2003/02/26 06:31:14 matt Exp $	*/
2 
3 /*-
4  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Public Access Networks Corporation ("Panix").  It was developed under
9  * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *	This product includes software developed by the NetBSD
22  *	Foundation, Inc. and its contributors.
23  * 4. Neither the name of The NetBSD Foundation nor the names of its
24  *    contributors may be used to endorse or promote products derived
25  *    from this software without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37  * POSSIBILITY OF SUCH DAMAGE.
38  */
39 
40 /*
41  * Copyright (c) 1982, 1986, 1988, 1993
42  *	The Regents of the University of California.  All rights reserved.
43  *
44  * Redistribution and use in source and binary forms, with or without
45  * modification, are permitted provided that the following conditions
46  * are met:
47  * 1. Redistributions of source code must retain the above copyright
48  *    notice, this list of conditions and the following disclaimer.
49  * 2. Redistributions in binary form must reproduce the above copyright
50  *    notice, this list of conditions and the following disclaimer in the
51  *    documentation and/or other materials provided with the distribution.
52  * 3. All advertising materials mentioning features or use of this software
53  *    must display the following acknowledgement:
54  *	This product includes software developed by the University of
55  *	California, Berkeley and its contributors.
56  * 4. Neither the name of the University nor the names of its contributors
57  *    may be used to endorse or promote products derived from this software
58  *    without specific prior written permission.
59  *
60  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
61  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
62  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
63  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
64  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
65  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
66  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
67  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
68  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
69  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
70  * SUCH DAMAGE.
71  *
72  *	@(#)if_ether.c	8.2 (Berkeley) 9/26/94
73  */
74 
75 /*
76  * Ethernet address resolution protocol.
77  * TODO:
78  *	add "inuse/lock" bit (or ref. count) along with valid bit
79  */
80 
81 #include <sys/cdefs.h>
82 __KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.92 2003/02/26 06:31:14 matt Exp $");
83 
84 #include "opt_ddb.h"
85 #include "opt_inet.h"
86 
87 #ifdef INET
88 
89 #include "bridge.h"
90 
91 #include <sys/param.h>
92 #include <sys/systm.h>
93 #include <sys/callout.h>
94 #include <sys/malloc.h>
95 #include <sys/mbuf.h>
96 #include <sys/socket.h>
97 #include <sys/time.h>
98 #include <sys/kernel.h>
99 #include <sys/errno.h>
100 #include <sys/ioctl.h>
101 #include <sys/syslog.h>
102 #include <sys/proc.h>
103 #include <sys/protosw.h>
104 #include <sys/domain.h>
105 
106 #include <net/ethertypes.h>
107 #include <net/if.h>
108 #include <net/if_dl.h>
109 #include <net/if_token.h>
110 #include <net/if_types.h>
111 #include <net/route.h>
112 
113 #include <netinet/in.h>
114 #include <netinet/in_systm.h>
115 #include <netinet/in_var.h>
116 #include <netinet/ip.h>
117 #include <netinet/if_inarp.h>
118 
119 #include "loop.h"
120 #include "arc.h"
121 #if NARC > 0
122 #include <net/if_arc.h>
123 #endif
124 #include "fddi.h"
125 #if NFDDI > 0
126 #include <net/if_fddi.h>
127 #endif
128 #include "token.h"
129 
130 #define SIN(s) ((struct sockaddr_in *)s)
131 #define SDL(s) ((struct sockaddr_dl *)s)
132 #define SRP(s) ((struct sockaddr_inarp *)s)
133 
134 /*
135  * ARP trailer negotiation.  Trailer protocol is not IP specific,
136  * but ARP request/response use IP addresses.
137  */
138 #define ETHERTYPE_IPTRAILERS ETHERTYPE_TRAIL
139 
140 /* timer values */
141 int	arpt_prune = (5*60*1);	/* walk list every 5 minutes */
142 int	arpt_keep = (20*60);	/* once resolved, good for 20 more minutes */
143 int	arpt_down = 20;		/* once declared down, don't send for 20 secs */
144 #define	rt_expire rt_rmx.rmx_expire
145 
146 extern	struct domain arpdomain;
147 
148 static	void arprequest __P((struct ifnet *,
149 	    struct in_addr *, struct in_addr *, u_int8_t *));
150 static	void arptfree __P((struct llinfo_arp *));
151 static	void arptimer __P((void *));
152 static	struct llinfo_arp *arplookup __P((struct mbuf *, struct in_addr *,
153 					  int, int));
154 static	void in_arpinput __P((struct mbuf *));
155 
156 #if NLOOP > 0
157 extern	struct ifnet loif[NLOOP];
158 #endif
159 LIST_HEAD(, llinfo_arp) llinfo_arp;
160 struct	ifqueue arpintrq = {0, 0, 0, 50};
161 int	arp_inuse, arp_allocated, arp_intimer;
162 int	arp_maxtries = 5;
163 int	useloopback = 1;	/* use loopback interface for local traffic */
164 int	arpinit_done = 0;
165 
166 struct	arpstat arpstat;
167 struct	callout arptimer_ch;
168 
169 
170 /* revarp state */
171 static struct	in_addr myip, srv_ip;
172 static int	myip_initialized = 0;
173 static int	revarp_in_progress = 0;
174 static struct	ifnet *myip_ifp = NULL;
175 
176 #ifdef DDB
177 static void db_print_sa __P((struct sockaddr *));
178 static void db_print_ifa __P((struct ifaddr *));
179 static void db_print_llinfo __P((caddr_t));
180 static int db_show_radix_node __P((struct radix_node *, void *));
181 #endif
182 
183 /*
184  * this should be elsewhere.
185  */
186 
187 static char *
188 lla_snprintf __P((u_int8_t *, int));
189 
190 static char *
191 lla_snprintf(adrp, len)
192 	u_int8_t *adrp;
193 	int len;
194 {
195 #define NUMBUFS 3
196 	static char buf[NUMBUFS][16*3];
197 	static int bnum = 0;
198 	static const char hexdigits[] = {
199 	    '0','1','2','3','4','5','6','7',
200 	    '8','9','a','b','c','d','e','f'
201 	};
202 
203 	int i;
204 	char *p;
205 
206 	p = buf[bnum];
207 
208 	*p++ = hexdigits[(*adrp)>>4];
209 	*p++ = hexdigits[(*adrp++)&0xf];
210 
211 	for (i=1; i<len && i<16; i++) {
212 		*p++ = ':';
213 		*p++ = hexdigits[(*adrp)>>4];
214 		*p++ = hexdigits[(*adrp++)&0xf];
215 	}
216 
217 	*p = 0;
218 	p = buf[bnum];
219 	bnum = (bnum + 1) % NUMBUFS;
220 	return p;
221 }
222 
223 struct protosw arpsw[] = {
224 	{ 0, 0, 0, 0,
225 	  0, 0, 0, 0,
226 	  0,
227 	  0, 0, 0, arp_drain,
228 	}
229 };
230 
231 
232 struct domain arpdomain =
233 { 	PF_ARP,  "arp", 0, 0, 0,
234 	arpsw, &arpsw[sizeof(arpsw)/sizeof(arpsw[0])]
235 };
236 
237 /*
238  * ARP table locking.
239  *
240  * to prevent lossage vs. the arp_drain routine (which may be called at
241  * any time, including in a device driver context), we do two things:
242  *
243  * 1) manipulation of la->la_hold is done at splnet() (for all of
244  * about two instructions).
245  *
246  * 2) manipulation of the arp table's linked list is done under the
247  * protection of the ARP_LOCK; if arp_drain() or arptimer is called
248  * while the arp table is locked, we punt and try again later.
249  */
250 
251 static int	arp_locked;
252 static __inline int arp_lock_try __P((int));
253 static __inline void arp_unlock __P((void));
254 
255 static __inline int
256 arp_lock_try(int recurse)
257 {
258 	int s;
259 
260 	/*
261 	 * Use splvm() -- we're blocking things that would cause
262 	 * mbuf allocation.
263 	 */
264 	s = splvm();
265 	if (!recurse && arp_locked) {
266 		splx(s);
267 		return (0);
268 	}
269 	arp_locked++;
270 	splx(s);
271 	return (1);
272 }
273 
274 static __inline void
275 arp_unlock()
276 {
277 	int s;
278 
279 	s = splvm();
280 	arp_locked--;
281 	splx(s);
282 }
283 
284 #ifdef DIAGNOSTIC
285 #define	ARP_LOCK(recurse)						\
286 do {									\
287 	if (arp_lock_try(recurse) == 0) {				\
288 		printf("%s:%d: arp already locked\n", __FILE__, __LINE__); \
289 		panic("arp_lock");					\
290 	}								\
291 } while (/*CONSTCOND*/ 0)
292 #define	ARP_LOCK_CHECK()						\
293 do {									\
294 	if (arp_locked == 0) {						\
295 		printf("%s:%d: arp lock not held\n", __FILE__, __LINE__); \
296 		panic("arp lock check");				\
297 	}								\
298 } while (/*CONSTCOND*/ 0)
299 #else
300 #define	ARP_LOCK(x)		(void) arp_lock_try(x)
301 #define	ARP_LOCK_CHECK()	/* nothing */
302 #endif
303 
304 #define	ARP_UNLOCK()		arp_unlock()
305 
306 /*
307  * ARP protocol drain routine.  Called when memory is in short supply.
308  * Called at splvm();
309  */
310 
311 void
312 arp_drain()
313 {
314 	struct llinfo_arp *la, *nla;
315 	int count = 0;
316 	struct mbuf *mold;
317 
318 	if (arp_lock_try(0) == 0) {
319 		printf("arp_drain: locked; punting\n");
320 		return;
321 	}
322 
323 	for (la = LIST_FIRST(&llinfo_arp); la != 0; la = nla) {
324 		nla = LIST_NEXT(la, la_list);
325 
326 		mold = la->la_hold;
327 		la->la_hold = 0;
328 
329 		if (mold) {
330 			m_freem(mold);
331 			count++;
332 		}
333 	}
334 	ARP_UNLOCK();
335 	arpstat.as_dfrdropped += count;
336 }
337 
338 
339 /*
340  * Timeout routine.  Age arp_tab entries periodically.
341  */
342 /* ARGSUSED */
343 static void
344 arptimer(arg)
345 	void *arg;
346 {
347 	int s;
348 	struct llinfo_arp *la, *nla;
349 
350 	s = splsoftnet();
351 
352 	if (arp_lock_try(0) == 0) {
353 		/* get it later.. */
354 		splx(s);
355 		return;
356 	}
357 
358 	callout_reset(&arptimer_ch, arpt_prune * hz, arptimer, NULL);
359 	for (la = LIST_FIRST(&llinfo_arp); la != 0; la = nla) {
360 		struct rtentry *rt = la->la_rt;
361 
362 		nla = LIST_NEXT(la, la_list);
363 		if (rt->rt_expire && rt->rt_expire <= time.tv_sec)
364 			arptfree(la); /* timer has expired; clear */
365 	}
366 
367 	ARP_UNLOCK();
368 
369 	splx(s);
370 }
371 
372 /*
373  * Parallel to llc_rtrequest.
374  */
375 void
376 arp_rtrequest(req, rt, info)
377 	int req;
378 	struct rtentry *rt;
379 	struct rt_addrinfo *info;
380 {
381 	struct sockaddr *gate = rt->rt_gateway;
382 	struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
383 	static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
384 	size_t allocsize;
385 	struct mbuf *mold;
386 	int s;
387 	struct in_ifaddr *ia;
388 	struct ifaddr *ifa;
389 
390 	if (!arpinit_done) {
391 		arpinit_done = 1;
392 		/*
393 		 * We generate expiration times from time.tv_sec
394 		 * so avoid accidently creating permanent routes.
395 		 */
396 		if (time.tv_sec == 0) {
397 			time.tv_sec++;
398 		}
399 		callout_init(&arptimer_ch);
400 		callout_reset(&arptimer_ch, hz, arptimer, NULL);
401 	}
402 
403 	if ((rt->rt_flags & RTF_GATEWAY) != 0) {
404 		if (req != RTM_ADD)
405 			return;
406 
407 		/*
408 		 * linklayers with particular link MTU limitation.
409 		 */
410 		switch(rt->rt_ifp->if_type) {
411 #if NFDDI > 0
412 		case IFT_FDDI:
413 			if (rt->rt_ifp->if_mtu > FDDIIPMTU)
414 				rt->rt_rmx.rmx_mtu = FDDIIPMTU;
415 			break;
416 #endif
417 #if NARC > 0
418 		case IFT_ARCNET:
419 		    {
420 			int arcipifmtu;
421 
422 			if (rt->rt_ifp->if_flags & IFF_LINK0)
423 				arcipifmtu = arc_ipmtu;
424 			else
425 				arcipifmtu = ARCMTU;
426 			if (rt->rt_ifp->if_mtu > arcipifmtu)
427 				rt->rt_rmx.rmx_mtu = arcipifmtu;
428 			break;
429 		    }
430 #endif
431 		}
432 		return;
433 	}
434 
435 	ARP_LOCK(1);		/* we may already be locked here. */
436 
437 	switch (req) {
438 
439 	case RTM_ADD:
440 		/*
441 		 * XXX: If this is a manually added route to interface
442 		 * such as older version of routed or gated might provide,
443 		 * restore cloning bit.
444 		 */
445 		if ((rt->rt_flags & RTF_HOST) == 0 &&
446 		    SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
447 			rt->rt_flags |= RTF_CLONING;
448 		if (rt->rt_flags & RTF_CLONING) {
449 			/*
450 			 * Case 1: This route should come from a route to iface.
451 			 */
452 			rt_setgate(rt, rt_key(rt),
453 					(struct sockaddr *)&null_sdl);
454 			gate = rt->rt_gateway;
455 			SDL(gate)->sdl_type = rt->rt_ifp->if_type;
456 			SDL(gate)->sdl_index = rt->rt_ifp->if_index;
457 			/*
458 			 * Give this route an expiration time, even though
459 			 * it's a "permanent" route, so that routes cloned
460 			 * from it do not need their expiration time set.
461 			 */
462 			rt->rt_expire = time.tv_sec;
463 			/*
464 			 * linklayers with particular link MTU limitation.
465 			 */
466 			switch (rt->rt_ifp->if_type) {
467 #if NFDDI > 0
468 			case IFT_FDDI:
469 				if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
470 				    (rt->rt_rmx.rmx_mtu > FDDIIPMTU ||
471 				     (rt->rt_rmx.rmx_mtu == 0 &&
472 				      rt->rt_ifp->if_mtu > FDDIIPMTU)))
473 					rt->rt_rmx.rmx_mtu = FDDIIPMTU;
474 				break;
475 #endif
476 #if NARC > 0
477 			case IFT_ARCNET:
478 			    {
479 				int arcipifmtu;
480 				if (rt->rt_ifp->if_flags & IFF_LINK0)
481 					arcipifmtu = arc_ipmtu;
482 				else
483 					arcipifmtu = ARCMTU;
484 
485 				if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
486 				    (rt->rt_rmx.rmx_mtu > arcipifmtu ||
487 				     (rt->rt_rmx.rmx_mtu == 0 &&
488 				      rt->rt_ifp->if_mtu > arcipifmtu)))
489 					rt->rt_rmx.rmx_mtu = arcipifmtu;
490 				break;
491 			    }
492 #endif
493 			}
494 			break;
495 		}
496 		/* Announce a new entry if requested. */
497 		if (rt->rt_flags & RTF_ANNOUNCE)
498 			arprequest(rt->rt_ifp,
499 			    &SIN(rt_key(rt))->sin_addr,
500 			    &SIN(rt_key(rt))->sin_addr,
501 			    (u_char *)LLADDR(SDL(gate)));
502 		/*FALLTHROUGH*/
503 	case RTM_RESOLVE:
504 		if (gate->sa_family != AF_LINK ||
505 		    gate->sa_len < sizeof(null_sdl)) {
506 			log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
507 			break;
508 		}
509 		SDL(gate)->sdl_type = rt->rt_ifp->if_type;
510 		SDL(gate)->sdl_index = rt->rt_ifp->if_index;
511 		if (la != 0)
512 			break; /* This happens on a route change */
513 		/*
514 		 * Case 2:  This route may come from cloning, or a manual route
515 		 * add with a LL address.
516 		 */
517 		switch (SDL(gate)->sdl_type) {
518 #if NTOKEN > 0
519 		case IFT_ISO88025:
520 			allocsize = sizeof(*la) + sizeof(struct token_rif);
521 			break;
522 #endif /* NTOKEN > 0 */
523 		default:
524 			allocsize = sizeof(*la);
525 		}
526 		R_Malloc(la, struct llinfo_arp *, allocsize);
527 		rt->rt_llinfo = (caddr_t)la;
528 		if (la == 0) {
529 			log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
530 			break;
531 		}
532 		arp_inuse++, arp_allocated++;
533 		Bzero(la, allocsize);
534 		la->la_rt = rt;
535 		rt->rt_flags |= RTF_LLINFO;
536 		LIST_INSERT_HEAD(&llinfo_arp, la, la_list);
537 
538 		INADDR_TO_IA(SIN(rt_key(rt))->sin_addr, ia);
539 		while (ia && ia->ia_ifp != rt->rt_ifp)
540 			NEXT_IA_WITH_SAME_ADDR(ia);
541 		if (ia) {
542 			/*
543 			 * This test used to be
544 			 *	if (loif.if_flags & IFF_UP)
545 			 * It allowed local traffic to be forced through
546 			 * the hardware by configuring the loopback down.
547 			 * However, it causes problems during network
548 			 * configuration for boards that can't receive
549 			 * packets they send.  It is now necessary to clear
550 			 * "useloopback" and remove the route to force
551 			 * traffic out to the hardware.
552 			 *
553 			 * In 4.4BSD, the above "if" statement checked
554 			 * rt->rt_ifa against rt_key(rt).  It was changed
555 			 * to the current form so that we can provide a
556 			 * better support for multiple IPv4 addresses on a
557 			 * interface.
558 			 */
559 			rt->rt_expire = 0;
560 			Bcopy(LLADDR(rt->rt_ifp->if_sadl),
561 			    LLADDR(SDL(gate)),
562 			    SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
563 #if NLOOP > 0
564 			if (useloopback)
565 				rt->rt_ifp = &loif[0];
566 #endif
567 			/*
568 			 * make sure to set rt->rt_ifa to the interface
569 			 * address we are using, otherwise we will have trouble
570 			 * with source address selection.
571 			 */
572 			ifa = &ia->ia_ifa;
573 			if (ifa != rt->rt_ifa) {
574 				IFAFREE(rt->rt_ifa);
575 				IFAREF(ifa);
576 				rt->rt_ifa = ifa;
577 			}
578 		}
579 		break;
580 
581 	case RTM_DELETE:
582 		if (la == 0)
583 			break;
584 		arp_inuse--;
585 		LIST_REMOVE(la, la_list);
586 		rt->rt_llinfo = 0;
587 		rt->rt_flags &= ~RTF_LLINFO;
588 
589 		s = splnet();
590 		mold = la->la_hold;
591 		la->la_hold = 0;
592 		splx(s);
593 
594 		if (mold)
595 			m_freem(mold);
596 
597 		Free((caddr_t)la);
598 	}
599 	ARP_UNLOCK();
600 }
601 
602 /*
603  * Broadcast an ARP request. Caller specifies:
604  *	- arp header source ip address
605  *	- arp header target ip address
606  *	- arp header source ethernet address
607  */
608 static void
609 arprequest(ifp, sip, tip, enaddr)
610 	struct ifnet *ifp;
611 	struct in_addr *sip, *tip;
612 	u_int8_t *enaddr;
613 {
614 	struct mbuf *m;
615 	struct arphdr *ah;
616 	struct sockaddr sa;
617 
618 	if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
619 		return;
620 	MCLAIM(m, &arpdomain.dom_mowner);
621 	switch (ifp->if_type) {
622 	case IFT_IEEE1394:
623 		m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
624 		    ifp->if_addrlen;
625 		break;
626 	default:
627 		m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
628 		    2 * ifp->if_addrlen;
629 		break;
630 	}
631 	m->m_pkthdr.len = m->m_len;
632 	MH_ALIGN(m, m->m_len);
633 	ah = mtod(m, struct arphdr *);
634 	bzero((caddr_t)ah, m->m_len);
635 	switch (ifp->if_type) {
636 	case IFT_IEEE1394:	/* RFC2734 */
637 		/* fill it now for ar_tpa computation */
638 		ah->ar_hrd = htons(ARPHRD_IEEE1394);
639 		break;
640 	default:
641 		/* ifp->if_output will fill ar_hrd */
642 		break;
643 	}
644 	ah->ar_pro = htons(ETHERTYPE_IP);
645 	ah->ar_hln = ifp->if_addrlen;		/* hardware address length */
646 	ah->ar_pln = sizeof(struct in_addr);	/* protocol address length */
647 	ah->ar_op = htons(ARPOP_REQUEST);
648 	bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
649 	bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
650 	bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
651 	sa.sa_family = AF_ARP;
652 	sa.sa_len = 2;
653 	m->m_flags |= M_BCAST;
654 	arpstat.as_sndtotal++;
655 	arpstat.as_sndrequest++;
656 	(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
657 }
658 
659 /*
660  * Resolve an IP address into an ethernet address.  If success,
661  * desten is filled in.  If there is no entry in arptab,
662  * set one up and broadcast a request for the IP address.
663  * Hold onto this mbuf and resend it once the address
664  * is finally resolved.  A return value of 1 indicates
665  * that desten has been filled in and the packet should be sent
666  * normally; a 0 return indicates that the packet has been
667  * taken over here, either now or for later transmission.
668  */
669 int
670 arpresolve(ifp, rt, m, dst, desten)
671 	struct ifnet *ifp;
672 	struct rtentry *rt;
673 	struct mbuf *m;
674 	struct sockaddr *dst;
675 	u_char *desten;
676 {
677 	struct llinfo_arp *la;
678 	struct sockaddr_dl *sdl;
679 	struct mbuf *mold;
680 	int s;
681 
682 	if (rt)
683 		la = (struct llinfo_arp *)rt->rt_llinfo;
684 	else {
685 		if ((la = arplookup(m, &SIN(dst)->sin_addr, 1, 0)) != NULL)
686 			rt = la->la_rt;
687 	}
688 	if (la == 0 || rt == 0) {
689 		arpstat.as_allocfail++;
690 		log(LOG_DEBUG,
691 		    "arpresolve: can't allocate llinfo on %s for %s\n",
692 		    ifp->if_xname, in_fmtaddr(SIN(dst)->sin_addr));
693 		m_freem(m);
694 		return (0);
695 	}
696 	sdl = SDL(rt->rt_gateway);
697 	/*
698 	 * Check the address family and length is valid, the address
699 	 * is resolved; otherwise, try to resolve.
700 	 */
701 	if ((rt->rt_expire == 0 || rt->rt_expire > time.tv_sec) &&
702 	    sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
703 		bcopy(LLADDR(sdl), desten,
704 		    min(sdl->sdl_alen, ifp->if_addrlen));
705 		return 1;
706 	}
707 	/*
708 	 * There is an arptab entry, but no ethernet address
709 	 * response yet.  Replace the held mbuf with this
710 	 * latest one.
711 	 */
712 
713 	arpstat.as_dfrtotal++;
714 	s = splnet();
715 	mold = la->la_hold;
716 	la->la_hold = m;
717 	splx(s);
718 
719 	if (mold) {
720 		arpstat.as_dfrdropped++;
721 		m_freem(mold);
722 	}
723 
724 	/*
725 	 * Re-send the ARP request when appropriate.
726 	 */
727 #ifdef	DIAGNOSTIC
728 	if (rt->rt_expire == 0) {
729 		/* This should never happen. (Should it? -gwr) */
730 		printf("arpresolve: unresolved and rt_expire == 0\n");
731 		/* Set expiration time to now (expired). */
732 		rt->rt_expire = time.tv_sec;
733 	}
734 #endif
735 	if (rt->rt_expire) {
736 		rt->rt_flags &= ~RTF_REJECT;
737 		if (la->la_asked == 0 || rt->rt_expire != time.tv_sec) {
738 			rt->rt_expire = time.tv_sec;
739 			if (la->la_asked++ < arp_maxtries)
740 				arprequest(ifp,
741 				    &SIN(rt->rt_ifa->ifa_addr)->sin_addr,
742 				    &SIN(dst)->sin_addr,
743 				    LLADDR(ifp->if_sadl));
744 			else {
745 				rt->rt_flags |= RTF_REJECT;
746 				rt->rt_expire += arpt_down;
747 				la->la_asked = 0;
748 			}
749 		}
750 	}
751 	return (0);
752 }
753 
754 /*
755  * Common length and type checks are done here,
756  * then the protocol-specific routine is called.
757  */
758 void
759 arpintr()
760 {
761 	struct mbuf *m;
762 	struct arphdr *ar;
763 	int s;
764 	int arplen;
765 
766 	while (arpintrq.ifq_head) {
767 		s = splnet();
768 		IF_DEQUEUE(&arpintrq, m);
769 		splx(s);
770 		if (m == 0 || (m->m_flags & M_PKTHDR) == 0)
771 			panic("arpintr");
772 
773 		MCLAIM(m, &arpdomain.dom_mowner);
774 		arpstat.as_rcvtotal++;
775 
776 		/*
777 		 * First, make sure we have at least struct arphdr.
778 		 */
779 		if (m->m_len < sizeof(struct arphdr) ||
780 		    (ar = mtod(m, struct arphdr *)) == NULL)
781 			goto badlen;
782 
783 		switch (m->m_pkthdr.rcvif->if_type) {
784 		case IFT_IEEE1394:
785 			arplen = sizeof(struct arphdr) +
786 			    ar->ar_hln + 2 * ar->ar_pln;
787 			break;
788 		default:
789 			arplen = sizeof(struct arphdr) +
790 			    2 * ar->ar_hln + 2 * ar->ar_pln;
791 			break;
792 		}
793 
794 		if (/* XXX ntohs(ar->ar_hrd) == ARPHRD_ETHER && */
795 		    m->m_len >= arplen)
796 			switch (ntohs(ar->ar_pro)) {
797 			case ETHERTYPE_IP:
798 			case ETHERTYPE_IPTRAILERS:
799 				in_arpinput(m);
800 				continue;
801 			default:
802 				arpstat.as_rcvbadproto++;
803 			}
804 		else {
805 badlen:
806 			arpstat.as_rcvbadlen++;
807 		}
808 		m_freem(m);
809 	}
810 }
811 
812 /*
813  * ARP for Internet protocols on 10 Mb/s Ethernet.
814  * Algorithm is that given in RFC 826.
815  * In addition, a sanity check is performed on the sender
816  * protocol address, to catch impersonators.
817  * We no longer handle negotiations for use of trailer protocol:
818  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
819  * along with IP replies if we wanted trailers sent to us,
820  * and also sent them in response to IP replies.
821  * This allowed either end to announce the desire to receive
822  * trailer packets.
823  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
824  * but formerly didn't normally send requests.
825  */
826 static void
827 in_arpinput(m)
828 	struct mbuf *m;
829 {
830 	struct arphdr *ah;
831 	struct ifnet *ifp = m->m_pkthdr.rcvif;
832 	struct llinfo_arp *la = 0;
833 	struct rtentry  *rt;
834 	struct in_ifaddr *ia;
835 #if NBRIDGE > 0
836 	struct in_ifaddr *bridge_ia = NULL;
837 #endif
838 	struct sockaddr_dl *sdl;
839 	struct sockaddr sa;
840 	struct in_addr isaddr, itaddr, myaddr;
841 	int op;
842 	struct mbuf *mold;
843 	int s;
844 
845 	ah = mtod(m, struct arphdr *);
846 	op = ntohs(ah->ar_op);
847 
848 	/*
849 	 * Fix up ah->ar_hrd if necessary, before using ar_tha() or
850 	 * ar_tpa().
851 	 */
852 	switch (ifp->if_type) {
853 	case IFT_IEEE1394:
854 		if (ntohs(ah->ar_hrd) == ARPHRD_IEEE1394)
855 			;
856 		else {
857 			/* XXX this is to make sure we compute ar_tha right */
858 			/* XXX check ar_hrd more strictly? */
859 			ah->ar_hrd = htons(ARPHRD_IEEE1394);
860 		}
861 		break;
862 	default:
863 		/* XXX check ar_hrd? */
864 		break;
865 	}
866 
867 	bcopy((caddr_t)ar_spa(ah), (caddr_t)&isaddr, sizeof (isaddr));
868 	bcopy((caddr_t)ar_tpa(ah), (caddr_t)&itaddr, sizeof (itaddr));
869 
870 	if (m->m_flags & (M_BCAST|M_MCAST))
871 		arpstat.as_rcvmcast++;
872 
873 	/*
874 	 * If the target IP address is zero, ignore the packet.
875 	 * This prevents the code below from tring to answer
876 	 * when we are using IP address zero (booting).
877 	 */
878 	if (in_nullhost(itaddr)) {
879 		arpstat.as_rcvzerotpa++;
880 		goto out;
881 	}
882 
883 	/*
884 	 * If the source IP address is zero, this is most likely a
885 	 * confused host trying to use IP address zero. (Windoze?)
886 	 * XXX: Should we bother trying to reply to these?
887 	 */
888 	if (in_nullhost(isaddr)) {
889 		arpstat.as_rcvzerospa++;
890 		goto out;
891 	}
892 
893 	/*
894 	 * Search for a matching interface address
895 	 * or any address on the interface to use
896 	 * as a dummy address in the rest of this function
897 	 */
898 	INADDR_TO_IA(itaddr, ia);
899 	while (ia != NULL) {
900 		if (ia->ia_ifp == m->m_pkthdr.rcvif)
901 			break;
902 
903 #if NBRIDGE > 0
904 		/*
905 		 * If the interface we received the packet on
906 		 * is part of a bridge, check to see if we need
907 		 * to "bridge" the packet to ourselves at this
908 		 * layer.  Note we still prefer a perfect match,
909 		 * but allow this weaker match if necessary.
910 		 */
911 		if (m->m_pkthdr.rcvif->if_bridge != NULL &&
912 		    m->m_pkthdr.rcvif->if_bridge == ia->ia_ifp->if_bridge)
913 			bridge_ia = ia;
914 #endif /* NBRIDGE > 0 */
915 
916 		NEXT_IA_WITH_SAME_ADDR(ia);
917 	}
918 
919 #if NBRIDGE > 0
920 	if (ia == NULL && bridge_ia != NULL) {
921 		ia = bridge_ia;
922 		ifp = bridge_ia->ia_ifp;
923 	}
924 #endif
925 
926 	if (ia == NULL) {
927 		INADDR_TO_IA(isaddr, ia);
928 		while ((ia != NULL) && ia->ia_ifp != m->m_pkthdr.rcvif)
929 			NEXT_IA_WITH_SAME_ADDR(ia);
930 
931 		if (ia == NULL) {
932 			IFP_TO_IA(ifp, ia);
933 			if (ia == NULL) {
934 				arpstat.as_rcvnoint++;
935 				goto out;
936 			}
937 		}
938 	}
939 
940 	myaddr = ia->ia_addr.sin_addr;
941 
942 	/* XXX checks for bridge case? */
943 	if (!bcmp((caddr_t)ar_sha(ah), LLADDR(ifp->if_sadl),
944 	    ifp->if_addrlen)) {
945 		arpstat.as_rcvlocalsha++;
946 		goto out;	/* it's from me, ignore it. */
947 	}
948 
949 	/* XXX checks for bridge case? */
950 	if (!bcmp((caddr_t)ar_sha(ah), (caddr_t)ifp->if_broadcastaddr,
951 	    ifp->if_addrlen)) {
952 		arpstat.as_rcvbcastsha++;
953 		log(LOG_ERR,
954 		    "%s: arp: link address is broadcast for IP address %s!\n",
955 		    ifp->if_xname, in_fmtaddr(isaddr));
956 		goto out;
957 	}
958 
959 	if (in_hosteq(isaddr, myaddr)) {
960 		arpstat.as_rcvlocalspa++;
961 		log(LOG_ERR,
962 		   "duplicate IP address %s sent from link address %s\n",
963 		   in_fmtaddr(isaddr), lla_snprintf(ar_sha(ah), ah->ar_hln));
964 		itaddr = myaddr;
965 		goto reply;
966 	}
967 	la = arplookup(m, &isaddr, in_hosteq(itaddr, myaddr), 0);
968 	if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) {
969 		if (sdl->sdl_alen &&
970 		    bcmp((caddr_t)ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
971 			if (rt->rt_flags & RTF_STATIC) {
972 				arpstat.as_rcvoverperm++;
973 				log(LOG_INFO,
974 				    "%s tried to overwrite permanent arp info"
975 				    " for %s\n",
976 				    lla_snprintf(ar_sha(ah), ah->ar_hln),
977 				    in_fmtaddr(isaddr));
978 				goto out;
979 			} else if (rt->rt_ifp != ifp) {
980 				arpstat.as_rcvoverint++;
981 				log(LOG_INFO,
982 				    "%s on %s tried to overwrite "
983 				    "arp info for %s on %s\n",
984 				    lla_snprintf(ar_sha(ah), ah->ar_hln),
985 				    ifp->if_xname, in_fmtaddr(isaddr),
986 				    rt->rt_ifp->if_xname);
987 				    goto out;
988 			} else {
989 				arpstat.as_rcvover++;
990 				log(LOG_INFO,
991 				    "arp info overwritten for %s by %s\n",
992 				    in_fmtaddr(isaddr),
993 				    lla_snprintf(ar_sha(ah), ah->ar_hln));
994 			}
995 		}
996 		/*
997 		 * sanity check for the address length.
998 		 * XXX this does not work for protocols with variable address
999 		 * length. -is
1000 		 */
1001 		if (sdl->sdl_alen &&
1002 		    sdl->sdl_alen != ah->ar_hln) {
1003 			arpstat.as_rcvlenchg++;
1004 			log(LOG_WARNING,
1005 			    "arp from %s: new addr len %d, was %d",
1006 			    in_fmtaddr(isaddr), ah->ar_hln, sdl->sdl_alen);
1007 		}
1008 		if (ifp->if_addrlen != ah->ar_hln) {
1009 			arpstat.as_rcvbadlen++;
1010 			log(LOG_WARNING,
1011 			    "arp from %s: addr len: new %d, i/f %d (ignored)",
1012 			    in_fmtaddr(isaddr), ah->ar_hln,
1013 			    ifp->if_addrlen);
1014 			goto reply;
1015 		}
1016 #if NTOKEN > 0
1017 		/*
1018 		 * XXX uses m_data and assumes the complete answer including
1019 		 * XXX token-ring headers is in the same buf
1020 		 */
1021 		if (ifp->if_type == IFT_ISO88025) {
1022 			struct token_header *trh;
1023 
1024 			trh = (struct token_header *)M_TRHSTART(m);
1025 			if (trh->token_shost[0] & TOKEN_RI_PRESENT) {
1026 				struct token_rif	*rif;
1027 				size_t	riflen;
1028 
1029 				rif = TOKEN_RIF(trh);
1030 				riflen = (ntohs(rif->tr_rcf) &
1031 				    TOKEN_RCF_LEN_MASK) >> 8;
1032 
1033 				if (riflen > 2 &&
1034 				    riflen < sizeof(struct token_rif) &&
1035 				    (riflen & 1) == 0) {
1036 					rif->tr_rcf ^= htons(TOKEN_RCF_DIRECTION);
1037 					rif->tr_rcf &= htons(~TOKEN_RCF_BROADCAST_MASK);
1038 					bcopy(rif, TOKEN_RIF(la), riflen);
1039 				}
1040 			}
1041 		}
1042 #endif /* NTOKEN > 0 */
1043 		bcopy((caddr_t)ar_sha(ah), LLADDR(sdl),
1044 		    sdl->sdl_alen = ah->ar_hln);
1045 		if (rt->rt_expire)
1046 			rt->rt_expire = time.tv_sec + arpt_keep;
1047 		rt->rt_flags &= ~RTF_REJECT;
1048 		la->la_asked = 0;
1049 
1050 		s = splnet();
1051 		mold = la->la_hold;
1052 		la->la_hold = 0;
1053 		splx(s);
1054 
1055 		if (mold) {
1056 			arpstat.as_dfrsent++;
1057 			(*ifp->if_output)(ifp, mold, rt_key(rt), rt);
1058 		}
1059 	}
1060 reply:
1061 	if (op != ARPOP_REQUEST) {
1062 		if (op == ARPOP_REPLY)
1063 			arpstat.as_rcvreply++;
1064 	out:
1065 		m_freem(m);
1066 		return;
1067 	}
1068 	arpstat.as_rcvrequest++;
1069 	if (in_hosteq(itaddr, myaddr)) {
1070 		/* I am the target */
1071 		if (ar_tha(ah))
1072 			bcopy((caddr_t)ar_sha(ah), (caddr_t)ar_tha(ah),
1073 			    ah->ar_hln);
1074 		bcopy(LLADDR(ifp->if_sadl), (caddr_t)ar_sha(ah), ah->ar_hln);
1075 	} else {
1076 		la = arplookup(m, &itaddr, 0, SIN_PROXY);
1077 		if (la == 0)
1078 			goto out;
1079 		rt = la->la_rt;
1080 		if (ar_tha(ah))
1081 			bcopy((caddr_t)ar_sha(ah), (caddr_t)ar_tha(ah),
1082 			    ah->ar_hln);
1083 		sdl = SDL(rt->rt_gateway);
1084 		bcopy(LLADDR(sdl), (caddr_t)ar_sha(ah), ah->ar_hln);
1085 	}
1086 
1087 	bcopy((caddr_t)ar_spa(ah), (caddr_t)ar_tpa(ah), ah->ar_pln);
1088 	bcopy((caddr_t)&itaddr, (caddr_t)ar_spa(ah), ah->ar_pln);
1089 	ah->ar_op = htons(ARPOP_REPLY);
1090 	ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1091 	switch (ifp->if_type) {
1092 	case IFT_IEEE1394:
1093 		/*
1094 		 * ieee1394 arp reply is broadcast
1095 		 */
1096 		m->m_flags &= ~M_MCAST;
1097 		m->m_flags |= M_BCAST;
1098 		m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + ah->ar_hln;
1099 		break;
1100 
1101 	default:
1102 		m->m_flags &= ~(M_BCAST|M_MCAST); /* never reply by broadcast */
1103 		m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1104 		break;
1105 	}
1106 	m->m_pkthdr.len = m->m_len;
1107 	sa.sa_family = AF_ARP;
1108 	sa.sa_len = 2;
1109 	arpstat.as_sndtotal++;
1110 	arpstat.as_sndreply++;
1111 	(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
1112 	return;
1113 }
1114 
1115 /*
1116  * Free an arp entry.
1117  */
1118 static void
1119 arptfree(la)
1120 	struct llinfo_arp *la;
1121 {
1122 	struct rtentry *rt = la->la_rt;
1123 	struct sockaddr_dl *sdl;
1124 
1125 	ARP_LOCK_CHECK();
1126 
1127 	if (rt == 0)
1128 		panic("arptfree");
1129 	if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) &&
1130 	    sdl->sdl_family == AF_LINK) {
1131 		sdl->sdl_alen = 0;
1132 		la->la_asked = 0;
1133 		rt->rt_flags &= ~RTF_REJECT;
1134 		return;
1135 	}
1136 	rtrequest(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt),
1137 	    0, (struct rtentry **)0);
1138 }
1139 
1140 /*
1141  * Lookup or enter a new address in arptab.
1142  */
1143 static struct llinfo_arp *
1144 arplookup(m, addr, create, proxy)
1145 	struct mbuf *m;
1146 	struct in_addr *addr;
1147 	int create, proxy;
1148 {
1149 	struct arphdr *ah;
1150 	struct ifnet *ifp = m->m_pkthdr.rcvif;
1151 	struct rtentry *rt;
1152 	static struct sockaddr_inarp sin;
1153 	const char *why = 0;
1154 
1155 	ah = mtod(m, struct arphdr *);
1156 	sin.sin_len = sizeof(sin);
1157 	sin.sin_family = AF_INET;
1158 	sin.sin_addr = *addr;
1159 	sin.sin_other = proxy ? SIN_PROXY : 0;
1160 	rt = rtalloc1(sintosa(&sin), create);
1161 	if (rt == 0)
1162 		return (0);
1163 	rt->rt_refcnt--;
1164 
1165 	if (rt->rt_flags & RTF_GATEWAY)
1166 		why = "host is not on local network";
1167 	else if ((rt->rt_flags & RTF_LLINFO) == 0) {
1168 		arpstat.as_allocfail++;
1169 		why = "could not allocate llinfo";
1170 	} else if (rt->rt_gateway->sa_family != AF_LINK)
1171 		why = "gateway route is not ours";
1172 	else
1173 		return ((struct llinfo_arp *)rt->rt_llinfo);
1174 
1175 	if (create)
1176 		log(LOG_DEBUG, "arplookup: unable to enter address"
1177 		    " for %s@%s on %s (%s)\n",
1178 		    in_fmtaddr(*addr), lla_snprintf(ar_sha(ah), ah->ar_hln),
1179 		    (ifp) ? ifp->if_xname : 0, why);
1180 	return (0);
1181 }
1182 
1183 int
1184 arpioctl(cmd, data)
1185 	u_long cmd;
1186 	caddr_t data;
1187 {
1188 
1189 	return (EOPNOTSUPP);
1190 }
1191 
1192 void
1193 arp_ifinit(ifp, ifa)
1194 	struct ifnet *ifp;
1195 	struct ifaddr *ifa;
1196 {
1197 	struct in_addr *ip;
1198 
1199 	/*
1200 	 * Warn the user if another station has this IP address,
1201 	 * but only if the interface IP address is not zero.
1202 	 */
1203 	ip = &IA_SIN(ifa)->sin_addr;
1204 	if (!in_nullhost(*ip))
1205 		arprequest(ifp, ip, ip, LLADDR(ifp->if_sadl));
1206 
1207 	ifa->ifa_rtrequest = arp_rtrequest;
1208 	ifa->ifa_flags |= RTF_CLONING;
1209 }
1210 
1211 /*
1212  * Called from 10 Mb/s Ethernet interrupt handlers
1213  * when ether packet type ETHERTYPE_REVARP
1214  * is received.  Common length and type checks are done here,
1215  * then the protocol-specific routine is called.
1216  */
1217 void
1218 revarpinput(m)
1219 	struct mbuf *m;
1220 {
1221 	struct arphdr *ar;
1222 
1223 	if (m->m_len < sizeof(struct arphdr))
1224 		goto out;
1225 	ar = mtod(m, struct arphdr *);
1226 #if 0 /* XXX I don't think we need this... and it will prevent other LL */
1227 	if (ntohs(ar->ar_hrd) != ARPHRD_ETHER)
1228 		goto out;
1229 #endif
1230 	if (m->m_len < sizeof(struct arphdr) + 2 * (ar->ar_hln + ar->ar_pln))
1231 		goto out;
1232 	switch (ntohs(ar->ar_pro)) {
1233 	case ETHERTYPE_IP:
1234 	case ETHERTYPE_IPTRAILERS:
1235 		in_revarpinput(m);
1236 		return;
1237 
1238 	default:
1239 		break;
1240 	}
1241 out:
1242 	m_freem(m);
1243 }
1244 
1245 /*
1246  * RARP for Internet protocols on 10 Mb/s Ethernet.
1247  * Algorithm is that given in RFC 903.
1248  * We are only using for bootstrap purposes to get an ip address for one of
1249  * our interfaces.  Thus we support no user-interface.
1250  *
1251  * Since the contents of the RARP reply are specific to the interface that
1252  * sent the request, this code must ensure that they are properly associated.
1253  *
1254  * Note: also supports ARP via RARP packets, per the RFC.
1255  */
1256 void
1257 in_revarpinput(m)
1258 	struct mbuf *m;
1259 {
1260 	struct ifnet *ifp;
1261 	struct arphdr *ah;
1262 	int op;
1263 
1264 	ah = mtod(m, struct arphdr *);
1265 	op = ntohs(ah->ar_op);
1266 
1267 	switch (m->m_pkthdr.rcvif->if_type) {
1268 	case IFT_IEEE1394:
1269 		/* ARP without target hardware address is not supported */
1270 		goto out;
1271 	default:
1272 		break;
1273 	}
1274 
1275 	switch (op) {
1276 	case ARPOP_REQUEST:
1277 	case ARPOP_REPLY:	/* per RFC */
1278 		in_arpinput(m);
1279 		return;
1280 	case ARPOP_REVREPLY:
1281 		break;
1282 	case ARPOP_REVREQUEST:	/* handled by rarpd(8) */
1283 	default:
1284 		goto out;
1285 	}
1286 	if (!revarp_in_progress)
1287 		goto out;
1288 	ifp = m->m_pkthdr.rcvif;
1289 	if (ifp != myip_ifp) /* !same interface */
1290 		goto out;
1291 	if (myip_initialized)
1292 		goto wake;
1293 	if (bcmp(ar_tha(ah), LLADDR(ifp->if_sadl), ifp->if_sadl->sdl_alen))
1294 		goto out;
1295 	bcopy((caddr_t)ar_spa(ah), (caddr_t)&srv_ip, sizeof(srv_ip));
1296 	bcopy((caddr_t)ar_tpa(ah), (caddr_t)&myip, sizeof(myip));
1297 	myip_initialized = 1;
1298 wake:	/* Do wakeup every time in case it was missed. */
1299 	wakeup((caddr_t)&myip);
1300 
1301 out:
1302 	m_freem(m);
1303 }
1304 
1305 /*
1306  * Send a RARP request for the ip address of the specified interface.
1307  * The request should be RFC 903-compliant.
1308  */
1309 void
1310 revarprequest(ifp)
1311 	struct ifnet *ifp;
1312 {
1313 	struct sockaddr sa;
1314 	struct mbuf *m;
1315 	struct arphdr *ah;
1316 
1317 	if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
1318 		return;
1319 	MCLAIM(m, &arpdomain.dom_mowner);
1320 	m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
1321 	    2*ifp->if_addrlen;
1322 	m->m_pkthdr.len = m->m_len;
1323 	MH_ALIGN(m, m->m_len);
1324 	ah = mtod(m, struct arphdr *);
1325 	bzero((caddr_t)ah, m->m_len);
1326 	ah->ar_pro = htons(ETHERTYPE_IP);
1327 	ah->ar_hln = ifp->if_addrlen;		/* hardware address length */
1328 	ah->ar_pln = sizeof(struct in_addr);	/* protocol address length */
1329 	ah->ar_op = htons(ARPOP_REVREQUEST);
1330 
1331 	bcopy(LLADDR(ifp->if_sadl), (caddr_t)ar_sha(ah), ah->ar_hln);
1332 	bcopy(LLADDR(ifp->if_sadl), (caddr_t)ar_tha(ah), ah->ar_hln);
1333 
1334 	sa.sa_family = AF_ARP;
1335 	sa.sa_len = 2;
1336 	m->m_flags |= M_BCAST;
1337 	(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
1338 
1339 }
1340 
1341 /*
1342  * RARP for the ip address of the specified interface, but also
1343  * save the ip address of the server that sent the answer.
1344  * Timeout if no response is received.
1345  */
1346 int
1347 revarpwhoarewe(ifp, serv_in, clnt_in)
1348 	struct ifnet *ifp;
1349 	struct in_addr *serv_in;
1350 	struct in_addr *clnt_in;
1351 {
1352 	int result, count = 20;
1353 
1354 	myip_initialized = 0;
1355 	myip_ifp = ifp;
1356 
1357 	revarp_in_progress = 1;
1358 	while (count--) {
1359 		revarprequest(ifp);
1360 		result = tsleep((caddr_t)&myip, PSOCK, "revarp", hz/2);
1361 		if (result != EWOULDBLOCK)
1362 			break;
1363 	}
1364 	revarp_in_progress = 0;
1365 
1366 	if (!myip_initialized)
1367 		return ENETUNREACH;
1368 
1369 	bcopy((caddr_t)&srv_ip, serv_in, sizeof(*serv_in));
1370 	bcopy((caddr_t)&myip, clnt_in, sizeof(*clnt_in));
1371 	return 0;
1372 }
1373 
1374 
1375 
1376 #ifdef DDB
1377 
1378 #include <machine/db_machdep.h>
1379 #include <ddb/db_interface.h>
1380 #include <ddb/db_output.h>
1381 static void
1382 db_print_sa(sa)
1383 	struct sockaddr *sa;
1384 {
1385 	int len;
1386 	u_char *p;
1387 
1388 	if (sa == 0) {
1389 		db_printf("[NULL]");
1390 		return;
1391 	}
1392 
1393 	p = (u_char*)sa;
1394 	len = sa->sa_len;
1395 	db_printf("[");
1396 	while (len > 0) {
1397 		db_printf("%d", *p);
1398 		p++; len--;
1399 		if (len) db_printf(",");
1400 	}
1401 	db_printf("]\n");
1402 }
1403 static void
1404 db_print_ifa(ifa)
1405 	struct ifaddr *ifa;
1406 {
1407 	if (ifa == 0)
1408 		return;
1409 	db_printf("  ifa_addr=");
1410 	db_print_sa(ifa->ifa_addr);
1411 	db_printf("  ifa_dsta=");
1412 	db_print_sa(ifa->ifa_dstaddr);
1413 	db_printf("  ifa_mask=");
1414 	db_print_sa(ifa->ifa_netmask);
1415 	db_printf("  flags=0x%x,refcnt=%d,metric=%d\n",
1416 			  ifa->ifa_flags,
1417 			  ifa->ifa_refcnt,
1418 			  ifa->ifa_metric);
1419 }
1420 static void
1421 db_print_llinfo(li)
1422 	caddr_t li;
1423 {
1424 	struct llinfo_arp *la;
1425 
1426 	if (li == 0)
1427 		return;
1428 	la = (struct llinfo_arp *)li;
1429 	db_printf("  la_rt=%p la_hold=%p, la_asked=0x%lx\n",
1430 			  la->la_rt, la->la_hold, la->la_asked);
1431 }
1432 /*
1433  * Function to pass to rn_walktree().
1434  * Return non-zero error to abort walk.
1435  */
1436 static int
1437 db_show_radix_node(rn, w)
1438 	struct radix_node *rn;
1439 	void *w;
1440 {
1441 	struct rtentry *rt = (struct rtentry *)rn;
1442 
1443 	db_printf("rtentry=%p", rt);
1444 
1445 	db_printf(" flags=0x%x refcnt=%d use=%ld expire=%ld\n",
1446 			  rt->rt_flags, rt->rt_refcnt,
1447 			  rt->rt_use, rt->rt_expire);
1448 
1449 	db_printf(" key="); db_print_sa(rt_key(rt));
1450 	db_printf(" mask="); db_print_sa(rt_mask(rt));
1451 	db_printf(" gw="); db_print_sa(rt->rt_gateway);
1452 
1453 	db_printf(" ifp=%p ", rt->rt_ifp);
1454 	if (rt->rt_ifp)
1455 		db_printf("(%s)", rt->rt_ifp->if_xname);
1456 	else
1457 		db_printf("(NULL)");
1458 
1459 	db_printf(" ifa=%p\n", rt->rt_ifa);
1460 	db_print_ifa(rt->rt_ifa);
1461 
1462 	db_printf(" genmask="); db_print_sa(rt->rt_genmask);
1463 
1464 	db_printf(" gwroute=%p llinfo=%p\n",
1465 			  rt->rt_gwroute, rt->rt_llinfo);
1466 	db_print_llinfo(rt->rt_llinfo);
1467 
1468 	return (0);
1469 }
1470 /*
1471  * Function to print all the route trees.
1472  * Use this from ddb:  "show arptab"
1473  */
1474 void
1475 db_show_arptab(addr, have_addr, count, modif)
1476 	db_expr_t	addr;
1477 	int		have_addr;
1478 	db_expr_t	count;
1479 	char *		modif;
1480 {
1481 	struct radix_node_head *rnh;
1482 	rnh = rt_tables[AF_INET];
1483 	db_printf("Route tree for AF_INET\n");
1484 	if (rnh == NULL) {
1485 		db_printf(" (not initialized)\n");
1486 		return;
1487 	}
1488 	rn_walktree(rnh, db_show_radix_node, NULL);
1489 	return;
1490 }
1491 #endif
1492 #endif /* INET */
1493