xref: /freebsd/sys/netinet/if_ether.c (revision 59e2ff550c448126b988150ce800cdf73bb5103e)
1 /*-
2  * Copyright (c) 1982, 1986, 1988, 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  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)if_ether.c	8.1 (Berkeley) 6/10/93
30  */
31 
32 /*
33  * Ethernet address resolution protocol.
34  * TODO:
35  *	add "inuse/lock" bit (or ref. count) along with valid bit
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include "opt_inet.h"
42 
43 #include <sys/param.h>
44 #include <sys/kernel.h>
45 #include <sys/lock.h>
46 #include <sys/queue.h>
47 #include <sys/sysctl.h>
48 #include <sys/systm.h>
49 #include <sys/mbuf.h>
50 #include <sys/malloc.h>
51 #include <sys/proc.h>
52 #include <sys/rmlock.h>
53 #include <sys/socket.h>
54 #include <sys/syslog.h>
55 
56 #include <net/if.h>
57 #include <net/if_var.h>
58 #include <net/if_dl.h>
59 #include <net/if_types.h>
60 #include <net/netisr.h>
61 #include <net/ethernet.h>
62 #include <net/route.h>
63 #include <net/vnet.h>
64 
65 #include <netinet/in.h>
66 #include <netinet/in_var.h>
67 #include <net/if_llatbl.h>
68 #include <netinet/if_ether.h>
69 #ifdef INET
70 #include <netinet/ip_carp.h>
71 #endif
72 
73 #include <security/mac/mac_framework.h>
74 
75 #define SIN(s) ((const struct sockaddr_in *)(s))
76 
77 static struct timeval arp_lastlog;
78 static int arp_curpps;
79 static int arp_maxpps = 1;
80 
81 SYSCTL_DECL(_net_link_ether);
82 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
83 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
84 
85 /* timer values */
86 static VNET_DEFINE(int, arpt_keep) = (20*60);	/* once resolved, good for 20
87 						 * minutes */
88 static VNET_DEFINE(int, arp_maxtries) = 5;
89 static VNET_DEFINE(int, arp_proxyall) = 0;
90 static VNET_DEFINE(int, arpt_down) = 20;	/* keep incomplete entries for
91 						 * 20 seconds */
92 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
93 VNET_PCPUSTAT_SYSINIT(arpstat);
94 
95 #ifdef VIMAGE
96 VNET_PCPUSTAT_SYSUNINIT(arpstat);
97 #endif /* VIMAGE */
98 
99 static VNET_DEFINE(int, arp_maxhold) = 1;
100 
101 #define	V_arpt_keep		VNET(arpt_keep)
102 #define	V_arpt_down		VNET(arpt_down)
103 #define	V_arp_maxtries		VNET(arp_maxtries)
104 #define	V_arp_proxyall		VNET(arp_proxyall)
105 #define	V_arp_maxhold		VNET(arp_maxhold)
106 
107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
108 	&VNET_NAME(arpt_keep), 0,
109 	"ARP entry lifetime in seconds");
110 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
111 	&VNET_NAME(arp_maxtries), 0,
112 	"ARP resolution attempts before returning error");
113 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
114 	&VNET_NAME(arp_proxyall), 0,
115 	"Enable proxy ARP for all suitable requests");
116 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
117 	&VNET_NAME(arpt_down), 0,
118 	"Incomplete ARP entry lifetime in seconds");
119 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
120     arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
121 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
122 	&VNET_NAME(arp_maxhold), 0,
123 	"Number of packets to hold per ARP entry");
124 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
125 	CTLFLAG_RW, &arp_maxpps, 0,
126 	"Maximum number of remotely triggered ARP messages that can be "
127 	"logged per second");
128 
129 #define	ARP_LOG(pri, ...)	do {					\
130 	if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps))	\
131 		log((pri), "arp: " __VA_ARGS__);			\
132 } while (0)
133 
134 
135 static void	arp_init(void);
136 static void	arpintr(struct mbuf *);
137 static void	arptimer(void *);
138 #ifdef INET
139 static void	in_arpinput(struct mbuf *);
140 #endif
141 
142 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
143     struct ifnet *ifp, int bridged, struct llentry *la);
144 static void arp_update_lle(struct arphdr *ah, struct ifnet *ifp,
145     struct llentry *la);
146 static void arp_mark_lle_reachable(struct llentry *la);
147 
148 
149 static const struct netisr_handler arp_nh = {
150 	.nh_name = "arp",
151 	.nh_handler = arpintr,
152 	.nh_proto = NETISR_ARP,
153 	.nh_policy = NETISR_POLICY_SOURCE,
154 };
155 
156 /*
157  * Timeout routine.  Age arp_tab entries periodically.
158  */
159 static void
160 arptimer(void *arg)
161 {
162 	struct llentry *lle = (struct llentry *)arg;
163 	struct ifnet *ifp;
164 
165 	if (lle->la_flags & LLE_STATIC) {
166 		return;
167 	}
168 	LLE_WLOCK(lle);
169 	if (callout_pending(&lle->lle_timer)) {
170 		/*
171 		 * Here we are a bit odd here in the treatment of
172 		 * active/pending. If the pending bit is set, it got
173 		 * rescheduled before I ran. The active
174 		 * bit we ignore, since if it was stopped
175 		 * in ll_tablefree() and was currently running
176 		 * it would have return 0 so the code would
177 		 * not have deleted it since the callout could
178 		 * not be stopped so we want to go through
179 		 * with the delete here now. If the callout
180 		 * was restarted, the pending bit will be back on and
181 		 * we just want to bail since the callout_reset would
182 		 * return 1 and our reference would have been removed
183 		 * by arpresolve() below.
184 		 */
185 		LLE_WUNLOCK(lle);
186  		return;
187  	}
188 	ifp = lle->lle_tbl->llt_ifp;
189 	CURVNET_SET(ifp->if_vnet);
190 
191 	if ((lle->la_flags & LLE_DELETED) == 0) {
192 		int evt;
193 
194 		if (lle->la_flags & LLE_VALID)
195 			evt = LLENTRY_EXPIRED;
196 		else
197 			evt = LLENTRY_TIMEDOUT;
198 		EVENTHANDLER_INVOKE(lle_event, lle, evt);
199 	}
200 
201 	callout_stop(&lle->lle_timer);
202 
203 	/* XXX: LOR avoidance. We still have ref on lle. */
204 	LLE_WUNLOCK(lle);
205 	IF_AFDATA_LOCK(ifp);
206 	LLE_WLOCK(lle);
207 
208 	/* Guard against race with other llentry_free(). */
209 	if (lle->la_flags & LLE_LINKED) {
210 		LLE_REMREF(lle);
211 		lltable_unlink_entry(lle->lle_tbl, lle);
212 	}
213 	IF_AFDATA_UNLOCK(ifp);
214 
215 	size_t pkts_dropped = llentry_free(lle);
216 
217 	ARPSTAT_ADD(dropped, pkts_dropped);
218 	ARPSTAT_INC(timeouts);
219 
220 	CURVNET_RESTORE();
221 }
222 
223 /*
224  * Broadcast an ARP request. Caller specifies:
225  *	- arp header source ip address
226  *	- arp header target ip address
227  *	- arp header source ethernet address
228  */
229 void
230 arprequest(struct ifnet *ifp, const struct in_addr *sip,
231     const struct in_addr *tip, u_char *enaddr)
232 {
233 	struct mbuf *m;
234 	struct arphdr *ah;
235 	struct sockaddr sa;
236 	u_char *carpaddr = NULL;
237 
238 	if (sip == NULL) {
239 		/*
240 		 * The caller did not supply a source address, try to find
241 		 * a compatible one among those assigned to this interface.
242 		 */
243 		struct ifaddr *ifa;
244 
245 		IF_ADDR_RLOCK(ifp);
246 		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
247 			if (ifa->ifa_addr->sa_family != AF_INET)
248 				continue;
249 
250 			if (ifa->ifa_carp) {
251 				if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
252 					continue;
253 				sip = &IA_SIN(ifa)->sin_addr;
254 			} else {
255 				carpaddr = NULL;
256 				sip = &IA_SIN(ifa)->sin_addr;
257 			}
258 
259 			if (0 == ((sip->s_addr ^ tip->s_addr) &
260 			    IA_MASKSIN(ifa)->sin_addr.s_addr))
261 				break;  /* found it. */
262 		}
263 		IF_ADDR_RUNLOCK(ifp);
264 		if (sip == NULL) {
265 			printf("%s: cannot find matching address\n", __func__);
266 			return;
267 		}
268 	}
269 	if (enaddr == NULL)
270 		enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
271 
272 	if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
273 		return;
274 	m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
275 		2 * ifp->if_addrlen;
276 	m->m_pkthdr.len = m->m_len;
277 	M_ALIGN(m, m->m_len);
278 	ah = mtod(m, struct arphdr *);
279 	bzero((caddr_t)ah, m->m_len);
280 #ifdef MAC
281 	mac_netinet_arp_send(ifp, m);
282 #endif
283 	ah->ar_pro = htons(ETHERTYPE_IP);
284 	ah->ar_hln = ifp->if_addrlen;		/* hardware address length */
285 	ah->ar_pln = sizeof(struct in_addr);	/* protocol address length */
286 	ah->ar_op = htons(ARPOP_REQUEST);
287 	bcopy(enaddr, ar_sha(ah), ah->ar_hln);
288 	bcopy(sip, ar_spa(ah), ah->ar_pln);
289 	bcopy(tip, ar_tpa(ah), ah->ar_pln);
290 	sa.sa_family = AF_ARP;
291 	sa.sa_len = 2;
292 	m->m_flags |= M_BCAST;
293 	m_clrprotoflags(m);	/* Avoid confusing lower layers. */
294 	(*ifp->if_output)(ifp, m, &sa, NULL);
295 	ARPSTAT_INC(txrequests);
296 }
297 
298 /*
299  * Resolve an IP address into an ethernet address - heavy version.
300  * Used internally by arpresolve().
301  * We have already checked than  we can't use existing lle without
302  * modification so we have to acquire LLE_EXCLUSIVE lle lock.
303  *
304  * On success, desten and flags are filled in and the function returns 0;
305  * If the packet must be held pending resolution, we return EWOULDBLOCK
306  * On other errors, we return the corresponding error code.
307  * Note that m_freem() handles NULL.
308  */
309 static int
310 arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m,
311 	const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
312 {
313 	struct llentry *la = NULL, *la_tmp;
314 	struct mbuf *curr = NULL;
315 	struct mbuf *next = NULL;
316 	int error, renew;
317 
318 	if (pflags != NULL)
319 		*pflags = 0;
320 
321 	if (create == 0) {
322 		IF_AFDATA_RLOCK(ifp);
323 		la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
324 		IF_AFDATA_RUNLOCK(ifp);
325 	}
326 	if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
327 		la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
328 		if (la == NULL) {
329 			log(LOG_DEBUG,
330 			    "arpresolve: can't allocate llinfo for %s on %s\n",
331 			    inet_ntoa(SIN(dst)->sin_addr), if_name(ifp));
332 			m_freem(m);
333 			return (EINVAL);
334 		}
335 
336 		IF_AFDATA_WLOCK(ifp);
337 		LLE_WLOCK(la);
338 		la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
339 		/* Prefer ANY existing lle over newly-created one */
340 		if (la_tmp == NULL)
341 			lltable_link_entry(LLTABLE(ifp), la);
342 		IF_AFDATA_WUNLOCK(ifp);
343 		if (la_tmp != NULL) {
344 			lltable_free_entry(LLTABLE(ifp), la);
345 			la = la_tmp;
346 		}
347 	}
348 	if (la == NULL) {
349 		m_freem(m);
350 		return (EINVAL);
351 	}
352 
353 	if ((la->la_flags & LLE_VALID) &&
354 	    ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
355 		bcopy(&la->ll_addr, desten, ifp->if_addrlen);
356 		renew = 0;
357 		/*
358 		 * If entry has an expiry time and it is approaching,
359 		 * see if we need to send an ARP request within this
360 		 * arpt_down interval.
361 		 */
362 		if (!(la->la_flags & LLE_STATIC) &&
363 		    time_uptime + la->la_preempt > la->la_expire) {
364 			renew = 1;
365 			la->la_preempt--;
366 		}
367 
368 		if (pflags != NULL)
369 			*pflags = la->la_flags;
370 
371 		LLE_WUNLOCK(la);
372 
373 		if (renew == 1)
374 			arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
375 
376 		return (0);
377 	}
378 
379 	renew = (la->la_asked == 0 || la->la_expire != time_uptime);
380 	/*
381 	 * There is an arptab entry, but no ethernet address
382 	 * response yet.  Add the mbuf to the list, dropping
383 	 * the oldest packet if we have exceeded the system
384 	 * setting.
385 	 */
386 	if (m != NULL) {
387 		if (la->la_numheld >= V_arp_maxhold) {
388 			if (la->la_hold != NULL) {
389 				next = la->la_hold->m_nextpkt;
390 				m_freem(la->la_hold);
391 				la->la_hold = next;
392 				la->la_numheld--;
393 				ARPSTAT_INC(dropped);
394 			}
395 		}
396 		if (la->la_hold != NULL) {
397 			curr = la->la_hold;
398 			while (curr->m_nextpkt != NULL)
399 				curr = curr->m_nextpkt;
400 			curr->m_nextpkt = m;
401 		} else
402 			la->la_hold = m;
403 		la->la_numheld++;
404 	}
405 	/*
406 	 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
407 	 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
408 	 * if we have already sent arp_maxtries ARP requests. Retransmit the
409 	 * ARP request, but not faster than one request per second.
410 	 */
411 	if (la->la_asked < V_arp_maxtries)
412 		error = EWOULDBLOCK;	/* First request. */
413 	else
414 		error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
415 
416 	if (renew) {
417 		int canceled;
418 
419 		LLE_ADDREF(la);
420 		la->la_expire = time_uptime;
421 		canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
422 		    arptimer, la);
423 		if (canceled)
424 			LLE_REMREF(la);
425 		la->la_asked++;
426 		LLE_WUNLOCK(la);
427 		arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
428 		return (error);
429 	}
430 
431 	LLE_WUNLOCK(la);
432 	return (error);
433 }
434 
435 /*
436  * Resolve an IP address into an ethernet address.
437  * On input:
438  *    ifp is the interface we use
439  *    is_gw != 0 if @dst represents gateway to some destination
440  *    m is the mbuf. May be NULL if we don't have a packet.
441  *    dst is the next hop,
442  *    desten is the storage to put LL address.
443  *    flags returns lle entry flags.
444  *
445  * On success, desten and flags are filled in and the function returns 0;
446  * If the packet must be held pending resolution, we return EWOULDBLOCK
447  * On other errors, we return the corresponding error code.
448  * Note that m_freem() handles NULL.
449  */
450 int
451 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
452 	const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
453 {
454 	struct llentry *la = 0;
455 	int renew;
456 
457 	if (pflags != NULL)
458 		*pflags = 0;
459 
460 	if (m != NULL) {
461 		if (m->m_flags & M_BCAST) {
462 			/* broadcast */
463 			(void)memcpy(desten,
464 			    ifp->if_broadcastaddr, ifp->if_addrlen);
465 			return (0);
466 		}
467 		if (m->m_flags & M_MCAST) {
468 			/* multicast */
469 			ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
470 			return (0);
471 		}
472 	}
473 
474 	IF_AFDATA_RLOCK(ifp);
475 	la = lla_lookup(LLTABLE(ifp), 0, dst);
476 	IF_AFDATA_RUNLOCK(ifp);
477 
478 	if (la == NULL)
479 		return (arpresolve_full(ifp, is_gw, 1, m, dst, desten, pflags));
480 
481 	if ((la->la_flags & LLE_VALID) &&
482 	    ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
483 		bcopy(&la->ll_addr, desten, ifp->if_addrlen);
484 		renew = 0;
485 		/*
486 		 * If entry has an expiry time and it is approaching,
487 		 * see if we need to send an ARP request within this
488 		 * arpt_down interval.
489 		 */
490 		if (!(la->la_flags & LLE_STATIC) &&
491 		    time_uptime + la->la_preempt > la->la_expire) {
492 			renew = 1;
493 			la->la_preempt--;
494 		}
495 
496 		if (pflags != NULL)
497 			*pflags = la->la_flags;
498 
499 		LLE_RUNLOCK(la);
500 
501 		if (renew == 1)
502 			arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
503 
504 		return (0);
505 	}
506 	LLE_RUNLOCK(la);
507 
508 	return (arpresolve_full(ifp, is_gw, 0, m, dst, desten, pflags));
509 }
510 
511 /*
512  * Common length and type checks are done here,
513  * then the protocol-specific routine is called.
514  */
515 static void
516 arpintr(struct mbuf *m)
517 {
518 	struct arphdr *ar;
519 	struct ifnet *ifp;
520 	char *layer;
521 	int hlen;
522 
523 	ifp = m->m_pkthdr.rcvif;
524 
525 	if (m->m_len < sizeof(struct arphdr) &&
526 	    ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
527 		ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
528 		    if_name(ifp));
529 		return;
530 	}
531 	ar = mtod(m, struct arphdr *);
532 
533 	/* Check if length is sufficient */
534 	if (m->m_len <  arphdr_len(ar)) {
535 		m = m_pullup(m, arphdr_len(ar));
536 		if (m == NULL) {
537 			ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
538 			    if_name(ifp));
539 			return;
540 		}
541 		ar = mtod(m, struct arphdr *);
542 	}
543 
544 	hlen = 0;
545 	layer = "";
546 	switch (ntohs(ar->ar_hrd)) {
547 	case ARPHRD_ETHER:
548 		hlen = ETHER_ADDR_LEN; /* RFC 826 */
549 		layer = "ethernet";
550 		break;
551 	case ARPHRD_IEEE802:
552 		hlen = 6; /* RFC 1390, FDDI_ADDR_LEN */
553 		layer = "fddi";
554 		break;
555 	case ARPHRD_ARCNET:
556 		hlen = 1; /* RFC 1201, ARC_ADDR_LEN */
557 		layer = "arcnet";
558 		break;
559 	case ARPHRD_INFINIBAND:
560 		hlen = 20;	/* RFC 4391, INFINIBAND_ALEN */
561 		layer = "infiniband";
562 		break;
563 	case ARPHRD_IEEE1394:
564 		hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
565 		layer = "firewire";
566 
567 		/*
568 		 * Restrict too long harware addresses.
569 		 * Currently we are capable of handling 20-byte
570 		 * addresses ( sizeof(lle->ll_addr) )
571 		 */
572 		if (ar->ar_hln >= 20)
573 			hlen = 16;
574 		break;
575 	default:
576 		ARP_LOG(LOG_NOTICE,
577 		    "packet with unknown harware format 0x%02d received on %s\n",
578 		    ntohs(ar->ar_hrd), if_name(ifp));
579 		m_freem(m);
580 		return;
581 	}
582 
583 	if (hlen != 0 && hlen != ar->ar_hln) {
584 		ARP_LOG(LOG_NOTICE,
585 		    "packet with invalid %s address length %d received on %s\n",
586 		    layer, ar->ar_hln, if_name(ifp));
587 		m_freem(m);
588 		return;
589 	}
590 
591 	ARPSTAT_INC(received);
592 	switch (ntohs(ar->ar_pro)) {
593 #ifdef INET
594 	case ETHERTYPE_IP:
595 		in_arpinput(m);
596 		return;
597 #endif
598 	}
599 	m_freem(m);
600 }
601 
602 #ifdef INET
603 /*
604  * ARP for Internet protocols on 10 Mb/s Ethernet.
605  * Algorithm is that given in RFC 826.
606  * In addition, a sanity check is performed on the sender
607  * protocol address, to catch impersonators.
608  * We no longer handle negotiations for use of trailer protocol:
609  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
610  * along with IP replies if we wanted trailers sent to us,
611  * and also sent them in response to IP replies.
612  * This allowed either end to announce the desire to receive
613  * trailer packets.
614  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
615  * but formerly didn't normally send requests.
616  */
617 static int log_arp_wrong_iface = 1;
618 static int log_arp_movements = 1;
619 static int log_arp_permanent_modify = 1;
620 static int allow_multicast = 0;
621 
622 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
623 	&log_arp_wrong_iface, 0,
624 	"log arp packets arriving on the wrong interface");
625 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
626 	&log_arp_movements, 0,
627 	"log arp replies from MACs different than the one in the cache");
628 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
629 	&log_arp_permanent_modify, 0,
630 	"log arp replies from MACs different than the one in the permanent arp entry");
631 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
632 	&allow_multicast, 0, "accept multicast addresses");
633 
634 static void
635 in_arpinput(struct mbuf *m)
636 {
637 	struct rm_priotracker in_ifa_tracker;
638 	struct arphdr *ah;
639 	struct ifnet *ifp = m->m_pkthdr.rcvif;
640 	struct llentry *la = NULL, *la_tmp;
641 	struct rtentry *rt;
642 	struct ifaddr *ifa;
643 	struct in_ifaddr *ia;
644 	struct sockaddr sa;
645 	struct in_addr isaddr, itaddr, myaddr;
646 	u_int8_t *enaddr = NULL;
647 	int op;
648 	int bridged = 0, is_bridge = 0;
649 	int carped;
650 	struct sockaddr_in sin;
651 	struct sockaddr *dst;
652 	sin.sin_len = sizeof(struct sockaddr_in);
653 	sin.sin_family = AF_INET;
654 	sin.sin_addr.s_addr = 0;
655 
656 	if (ifp->if_bridge)
657 		bridged = 1;
658 	if (ifp->if_type == IFT_BRIDGE)
659 		is_bridge = 1;
660 
661 	/*
662 	 * We already have checked that mbuf contains enough contiguous data
663 	 * to hold entire arp message according to the arp header.
664 	 */
665 	ah = mtod(m, struct arphdr *);
666 
667 	/*
668 	 * ARP is only for IPv4 so we can reject packets with
669 	 * a protocol length not equal to an IPv4 address.
670 	 */
671 	if (ah->ar_pln != sizeof(struct in_addr)) {
672 		ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
673 		    sizeof(struct in_addr));
674 		goto drop;
675 	}
676 
677 	if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
678 		ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
679 		    ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
680 		goto drop;
681 	}
682 
683 	op = ntohs(ah->ar_op);
684 	(void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
685 	(void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
686 
687 	if (op == ARPOP_REPLY)
688 		ARPSTAT_INC(rxreplies);
689 
690 	/*
691 	 * For a bridge, we want to check the address irrespective
692 	 * of the receive interface. (This will change slightly
693 	 * when we have clusters of interfaces).
694 	 */
695 	IN_IFADDR_RLOCK(&in_ifa_tracker);
696 	LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
697 		if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
698 		    ia->ia_ifp == ifp) &&
699 		    itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
700 		    (ia->ia_ifa.ifa_carp == NULL ||
701 		    (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
702 			ifa_ref(&ia->ia_ifa);
703 			IN_IFADDR_RUNLOCK(&in_ifa_tracker);
704 			goto match;
705 		}
706 	}
707 	LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
708 		if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
709 		    ia->ia_ifp == ifp) &&
710 		    isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
711 			ifa_ref(&ia->ia_ifa);
712 			IN_IFADDR_RUNLOCK(&in_ifa_tracker);
713 			goto match;
714 		}
715 
716 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)				\
717   (ia->ia_ifp->if_bridge == ifp->if_softc &&				\
718   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&	\
719   addr == ia->ia_addr.sin_addr.s_addr)
720 	/*
721 	 * Check the case when bridge shares its MAC address with
722 	 * some of its children, so packets are claimed by bridge
723 	 * itself (bridge_input() does it first), but they are really
724 	 * meant to be destined to the bridge member.
725 	 */
726 	if (is_bridge) {
727 		LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
728 			if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
729 				ifa_ref(&ia->ia_ifa);
730 				ifp = ia->ia_ifp;
731 				IN_IFADDR_RUNLOCK(&in_ifa_tracker);
732 				goto match;
733 			}
734 		}
735 	}
736 #undef BDG_MEMBER_MATCHES_ARP
737 	IN_IFADDR_RUNLOCK(&in_ifa_tracker);
738 
739 	/*
740 	 * No match, use the first inet address on the receive interface
741 	 * as a dummy address for the rest of the function.
742 	 */
743 	IF_ADDR_RLOCK(ifp);
744 	TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
745 		if (ifa->ifa_addr->sa_family == AF_INET &&
746 		    (ifa->ifa_carp == NULL ||
747 		    (*carp_iamatch_p)(ifa, &enaddr))) {
748 			ia = ifatoia(ifa);
749 			ifa_ref(ifa);
750 			IF_ADDR_RUNLOCK(ifp);
751 			goto match;
752 		}
753 	IF_ADDR_RUNLOCK(ifp);
754 
755 	/*
756 	 * If bridging, fall back to using any inet address.
757 	 */
758 	IN_IFADDR_RLOCK(&in_ifa_tracker);
759 	if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
760 		IN_IFADDR_RUNLOCK(&in_ifa_tracker);
761 		goto drop;
762 	}
763 	ifa_ref(&ia->ia_ifa);
764 	IN_IFADDR_RUNLOCK(&in_ifa_tracker);
765 match:
766 	if (!enaddr)
767 		enaddr = (u_int8_t *)IF_LLADDR(ifp);
768 	carped = (ia->ia_ifa.ifa_carp != NULL);
769 	myaddr = ia->ia_addr.sin_addr;
770 	ifa_free(&ia->ia_ifa);
771 	if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
772 		goto drop;	/* it's from me, ignore it. */
773 	if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
774 		ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
775 		    "%s!\n", inet_ntoa(isaddr));
776 		goto drop;
777 	}
778 
779 	if (ifp->if_addrlen != ah->ar_hln) {
780 		ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
781 		    "i/f %d (ignored)\n", ifp->if_addrlen,
782 		    (u_char *) ar_sha(ah), ":", ah->ar_hln,
783 		    ifp->if_addrlen);
784 		goto drop;
785 	}
786 
787 	/*
788 	 * Warn if another host is using the same IP address, but only if the
789 	 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
790 	 * case we suppress the warning to avoid false positive complaints of
791 	 * potential misconfiguration.
792 	 */
793 	if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
794 	    myaddr.s_addr != 0) {
795 		ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
796 		   ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
797 		   inet_ntoa(isaddr), ifp->if_xname);
798 		itaddr = myaddr;
799 		ARPSTAT_INC(dupips);
800 		goto reply;
801 	}
802 	if (ifp->if_flags & IFF_STATICARP)
803 		goto reply;
804 
805 	bzero(&sin, sizeof(sin));
806 	sin.sin_len = sizeof(struct sockaddr_in);
807 	sin.sin_family = AF_INET;
808 	sin.sin_addr = isaddr;
809 	dst = (struct sockaddr *)&sin;
810 	IF_AFDATA_RLOCK(ifp);
811 	la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
812 	IF_AFDATA_RUNLOCK(ifp);
813 	if (la != NULL)
814 		arp_check_update_lle(ah, isaddr, ifp, bridged, la);
815 	else if (itaddr.s_addr == myaddr.s_addr) {
816 		/*
817 		 * Reply to our address, but no lle exists yet.
818 		 * do we really have to create an entry?
819 		 */
820 		la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
821 		if (la == NULL)
822 			goto drop;
823 		arp_update_lle(ah, ifp, la);
824 
825 		IF_AFDATA_WLOCK(ifp);
826 		LLE_WLOCK(la);
827 		la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
828 
829 		/*
830 		 * Check if lle still does not exists.
831 		 * If it does, that means that we either
832 		 * 1) have configured it explicitly, via
833 		 * 1a) 'arp -s' static entry or
834 		 * 1b) interface address static record
835 		 * or
836 		 * 2) it was the result of sending first packet to-host
837 		 * or
838 		 * 3) it was another arp reply packet we handled in
839 		 * different thread.
840 		 *
841 		 * In all cases except 3) we definitely need to prefer
842 		 * existing lle. For the sake of simplicity, prefer any
843 		 * existing lle over newly-create one.
844 		 */
845 		if (la_tmp == NULL)
846 			lltable_link_entry(LLTABLE(ifp), la);
847 		IF_AFDATA_WUNLOCK(ifp);
848 
849 		if (la_tmp == NULL) {
850 			arp_mark_lle_reachable(la);
851 			LLE_WUNLOCK(la);
852 		} else {
853 			/* Free newly-create entry and handle packet */
854 			lltable_free_entry(LLTABLE(ifp), la);
855 			la = la_tmp;
856 			la_tmp = NULL;
857 			arp_check_update_lle(ah, isaddr, ifp, bridged, la);
858 			/* arp_check_update_lle() returns @la unlocked */
859 		}
860 		la = NULL;
861 	}
862 reply:
863 	if (op != ARPOP_REQUEST)
864 		goto drop;
865 	ARPSTAT_INC(rxrequests);
866 
867 	if (itaddr.s_addr == myaddr.s_addr) {
868 		/* Shortcut.. the receiving interface is the target. */
869 		(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
870 		(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
871 	} else {
872 		struct llentry *lle = NULL;
873 
874 		sin.sin_addr = itaddr;
875 		IF_AFDATA_RLOCK(ifp);
876 		lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
877 		IF_AFDATA_RUNLOCK(ifp);
878 
879 		if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
880 			(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
881 			(void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
882 			LLE_RUNLOCK(lle);
883 		} else {
884 
885 			if (lle != NULL)
886 				LLE_RUNLOCK(lle);
887 
888 			if (!V_arp_proxyall)
889 				goto drop;
890 
891 			sin.sin_addr = itaddr;
892 			/* XXX MRT use table 0 for arp reply  */
893 			rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
894 			if (!rt)
895 				goto drop;
896 
897 			/*
898 			 * Don't send proxies for nodes on the same interface
899 			 * as this one came out of, or we'll get into a fight
900 			 * over who claims what Ether address.
901 			 */
902 			if (!rt->rt_ifp || rt->rt_ifp == ifp) {
903 				RTFREE_LOCKED(rt);
904 				goto drop;
905 			}
906 			RTFREE_LOCKED(rt);
907 
908 			(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
909 			(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
910 
911 			/*
912 			 * Also check that the node which sent the ARP packet
913 			 * is on the interface we expect it to be on. This
914 			 * avoids ARP chaos if an interface is connected to the
915 			 * wrong network.
916 			 */
917 			sin.sin_addr = isaddr;
918 
919 			/* XXX MRT use table 0 for arp checks */
920 			rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
921 			if (!rt)
922 				goto drop;
923 			if (rt->rt_ifp != ifp) {
924 				ARP_LOG(LOG_INFO, "proxy: ignoring request"
925 				    " from %s via %s, expecting %s\n",
926 				    inet_ntoa(isaddr), ifp->if_xname,
927 				    rt->rt_ifp->if_xname);
928 				RTFREE_LOCKED(rt);
929 				goto drop;
930 			}
931 			RTFREE_LOCKED(rt);
932 
933 #ifdef DEBUG_PROXY
934 			printf("arp: proxying for %s\n", inet_ntoa(itaddr));
935 #endif
936 		}
937 	}
938 
939 	if (itaddr.s_addr == myaddr.s_addr &&
940 	    IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
941 		/* RFC 3927 link-local IPv4; always reply by broadcast. */
942 #ifdef DEBUG_LINKLOCAL
943 		printf("arp: sending reply for link-local addr %s\n",
944 		    inet_ntoa(itaddr));
945 #endif
946 		m->m_flags |= M_BCAST;
947 		m->m_flags &= ~M_MCAST;
948 	} else {
949 		/* default behaviour; never reply by broadcast. */
950 		m->m_flags &= ~(M_BCAST|M_MCAST);
951 	}
952 	(void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
953 	(void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
954 	ah->ar_op = htons(ARPOP_REPLY);
955 	ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
956 	m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
957 	m->m_pkthdr.len = m->m_len;
958 	m->m_pkthdr.rcvif = NULL;
959 	sa.sa_family = AF_ARP;
960 	sa.sa_len = 2;
961 	m_clrprotoflags(m);	/* Avoid confusing lower layers. */
962 	(*ifp->if_output)(ifp, m, &sa, NULL);
963 	ARPSTAT_INC(txreplies);
964 	return;
965 
966 drop:
967 	m_freem(m);
968 }
969 #endif
970 
971 /*
972  * Checks received arp data against existing @la.
973  * Updates lle state/performs notification if necessary.
974  */
975 static void
976 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
977     int bridged, struct llentry *la)
978 {
979 	struct sockaddr sa;
980 	struct mbuf *m_hold, *m_hold_next;
981 
982 	LLE_WLOCK_ASSERT(la);
983 
984 	/* the following is not an error when doing bridging */
985 	if (!bridged && la->lle_tbl->llt_ifp != ifp) {
986 		if (log_arp_wrong_iface)
987 			ARP_LOG(LOG_WARNING, "%s is on %s "
988 			    "but got reply from %*D on %s\n",
989 			    inet_ntoa(isaddr),
990 			    la->lle_tbl->llt_ifp->if_xname,
991 			    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
992 			    ifp->if_xname);
993 		LLE_WUNLOCK(la);
994 		return;
995 	}
996 	if ((la->la_flags & LLE_VALID) &&
997 	    bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
998 		if (la->la_flags & LLE_STATIC) {
999 			LLE_WUNLOCK(la);
1000 			if (log_arp_permanent_modify)
1001 				ARP_LOG(LOG_ERR,
1002 				    "%*D attempts to modify "
1003 				    "permanent entry for %s on %s\n",
1004 				    ifp->if_addrlen,
1005 				    (u_char *)ar_sha(ah), ":",
1006 				    inet_ntoa(isaddr), ifp->if_xname);
1007 			return;
1008 		}
1009 		if (log_arp_movements) {
1010 			ARP_LOG(LOG_INFO, "%s moved from %*D "
1011 			    "to %*D on %s\n",
1012 			    inet_ntoa(isaddr),
1013 			    ifp->if_addrlen,
1014 			    (u_char *)&la->ll_addr, ":",
1015 			    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1016 			    ifp->if_xname);
1017 		}
1018 	}
1019 
1020 	/* Check if something has changed */
1021 	if (memcmp(&la->ll_addr, ar_sha(ah), ifp->if_addrlen) != 0 ||
1022 	    (la->la_flags & LLE_VALID) == 0) {
1023 		/* Perform real LLE update */
1024 		/* use afdata WLOCK to update fields */
1025 		LLE_ADDREF(la);
1026 		LLE_WUNLOCK(la);
1027 		IF_AFDATA_WLOCK(ifp);
1028 		LLE_WLOCK(la);
1029 
1030 		/*
1031 		 * Since we droppped LLE lock, other thread might have deleted
1032 		 * this lle. Check and return
1033 		 */
1034 		if ((la->la_flags & LLE_DELETED) != 0) {
1035 			IF_AFDATA_WUNLOCK(ifp);
1036 			LLE_FREE_LOCKED(la);
1037 			return;
1038 		}
1039 
1040 		/* Update data */
1041 		arp_update_lle(ah, ifp, la);
1042 
1043 		IF_AFDATA_WUNLOCK(ifp);
1044 		LLE_REMREF(la);
1045 	}
1046 
1047 	arp_mark_lle_reachable(la);
1048 
1049 	/*
1050 	 * The packets are all freed within the call to the output
1051 	 * routine.
1052 	 *
1053 	 * NB: The lock MUST be released before the call to the
1054 	 * output routine.
1055 	 */
1056 	if (la->la_hold != NULL) {
1057 		m_hold = la->la_hold;
1058 		la->la_hold = NULL;
1059 		la->la_numheld = 0;
1060 		lltable_fill_sa_entry(la, &sa);
1061 		LLE_WUNLOCK(la);
1062 		for (; m_hold != NULL; m_hold = m_hold_next) {
1063 			m_hold_next = m_hold->m_nextpkt;
1064 			m_hold->m_nextpkt = NULL;
1065 			/* Avoid confusing lower layers. */
1066 			m_clrprotoflags(m_hold);
1067 			(*ifp->if_output)(ifp, m_hold, &sa, NULL);
1068 		}
1069 	} else
1070 		LLE_WUNLOCK(la);
1071 }
1072 
1073 /*
1074  * Updates @la fields used by fast path code.
1075  */
1076 static void
1077 arp_update_lle(struct arphdr *ah, struct ifnet *ifp, struct llentry *la)
1078 {
1079 
1080 	memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
1081 	la->la_flags |= LLE_VALID;
1082 }
1083 
1084 static void
1085 arp_mark_lle_reachable(struct llentry *la)
1086 {
1087 	int canceled;
1088 
1089 	LLE_WLOCK_ASSERT(la);
1090 
1091 	EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1092 
1093 	if (!(la->la_flags & LLE_STATIC)) {
1094 		LLE_ADDREF(la);
1095 		la->la_expire = time_uptime + V_arpt_keep;
1096 		canceled = callout_reset(&la->lle_timer,
1097 		    hz * V_arpt_keep, arptimer, la);
1098 		if (canceled)
1099 			LLE_REMREF(la);
1100 	}
1101 	la->la_asked = 0;
1102 	la->la_preempt = V_arp_maxtries;
1103 }
1104 
1105 void
1106 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1107 {
1108 	struct llentry *lle, *lle_tmp;
1109 	struct sockaddr_in *dst_in;
1110 	struct sockaddr *dst;
1111 
1112 	if (ifa->ifa_carp != NULL)
1113 		return;
1114 
1115 	ifa->ifa_rtrequest = NULL;
1116 
1117 	dst_in = IA_SIN(ifa);
1118 	dst = (struct sockaddr *)dst_in;
1119 
1120 	if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) == INADDR_ANY)
1121 		return;
1122 
1123 	arprequest(ifp, &IA_SIN(ifa)->sin_addr,
1124 			&IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
1125 
1126 	/*
1127 	 * Interface address LLE record is considered static
1128 	 * because kernel code relies on LLE_STATIC flag to check
1129 	 * if these entries can be rewriten by arp updates.
1130 	 */
1131 	lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1132 	if (lle == NULL) {
1133 		log(LOG_INFO, "arp_ifinit: cannot create arp "
1134 		    "entry for interface address\n");
1135 		return;
1136 	}
1137 
1138 	IF_AFDATA_WLOCK(ifp);
1139 	LLE_WLOCK(lle);
1140 	/* Unlink any entry if exists */
1141 	lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1142 	if (lle_tmp != NULL)
1143 		lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1144 
1145 	lltable_link_entry(LLTABLE(ifp), lle);
1146 	IF_AFDATA_WUNLOCK(ifp);
1147 
1148 	if (lle_tmp != NULL)
1149 		EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1150 
1151 	EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1152 	LLE_WUNLOCK(lle);
1153 	if (lle_tmp != NULL)
1154 		lltable_free_entry(LLTABLE(ifp), lle_tmp);
1155 }
1156 
1157 void
1158 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
1159 {
1160 	if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
1161 		arprequest(ifp, &IA_SIN(ifa)->sin_addr,
1162 				&IA_SIN(ifa)->sin_addr, enaddr);
1163 	ifa->ifa_rtrequest = NULL;
1164 }
1165 
1166 static void
1167 arp_init(void)
1168 {
1169 
1170 	netisr_register(&arp_nh);
1171 }
1172 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
1173