2 * Copyright (c) 1982, 1986, 1988, 1993
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6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
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19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93
33 * Ethernet address resolution protocol.
35 * add "inuse/lock" bit (or ref. count) along with valid bit
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
43 #include <sys/param.h>
44 #include <sys/kernel.h>
45 #include <sys/queue.h>
46 #include <sys/sysctl.h>
47 #include <sys/systm.h>
49 #include <sys/malloc.h>
51 #include <sys/socket.h>
52 #include <sys/syslog.h>
55 #include <net/if_var.h>
56 #include <net/if_dl.h>
57 #include <net/if_types.h>
58 #include <net/netisr.h>
59 #include <net/if_llc.h>
60 #include <net/ethernet.h>
61 #include <net/route.h>
64 #include <netinet/in.h>
65 #include <netinet/in_var.h>
66 #include <net/if_llatbl.h>
67 #include <netinet/if_ether.h>
69 #include <netinet/ip_carp.h>
72 #include <net/if_arc.h>
73 #include <net/iso88025.h>
75 #include <security/mac/mac_framework.h>
77 #define SIN(s) ((const struct sockaddr_in *)(s))
78 #define SDL(s) ((struct sockaddr_dl *)s)
80 SYSCTL_DECL(_net_link_ether);
81 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
82 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
85 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20
87 static VNET_DEFINE(int, arp_maxtries) = 5;
88 static VNET_DEFINE(int, arp_proxyall) = 0;
89 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for
91 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
92 VNET_PCPUSTAT_SYSINIT(arpstat);
95 VNET_PCPUSTAT_SYSUNINIT(arpstat);
98 static VNET_DEFINE(int, arp_maxhold) = 1;
100 #define V_arpt_keep VNET(arpt_keep)
101 #define V_arpt_down VNET(arpt_down)
102 #define V_arp_maxtries VNET(arp_maxtries)
103 #define V_arp_proxyall VNET(arp_proxyall)
104 #define V_arp_maxhold VNET(arp_maxhold)
106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
107 &VNET_NAME(arpt_keep), 0,
108 "ARP entry lifetime in seconds");
109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
110 &VNET_NAME(arp_maxtries), 0,
111 "ARP resolution attempts before returning error");
112 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
113 &VNET_NAME(arp_proxyall), 0,
114 "Enable proxy ARP for all suitable requests");
115 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW,
116 &VNET_NAME(arpt_down), 0,
117 "Incomplete ARP entry lifetime in seconds");
118 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
119 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
120 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
121 &VNET_NAME(arp_maxhold), 0,
122 "Number of packets to hold per ARP entry");
124 static void arp_init(void);
125 static void arpintr(struct mbuf *);
126 static void arptimer(void *);
128 static void in_arpinput(struct mbuf *);
131 static const struct netisr_handler arp_nh = {
133 .nh_handler = arpintr,
134 .nh_proto = NETISR_ARP,
135 .nh_policy = NETISR_POLICY_SOURCE,
140 * called by in_scrubprefix() to remove entry from the table when
141 * the interface goes away
144 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
146 struct sockaddr_in addr4;
148 bzero((void *)&addr4, sizeof(addr4));
149 addr4.sin_len = sizeof(addr4);
150 addr4.sin_family = AF_INET;
151 addr4.sin_addr.s_addr = addr;
152 IF_AFDATA_RLOCK(ifp);
153 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
154 (struct sockaddr *)&addr4);
155 IF_AFDATA_RUNLOCK(ifp);
160 * Timeout routine. Age arp_tab entries periodically.
165 struct llentry *lle = (struct llentry *)arg;
168 if (lle->la_flags & LLE_STATIC) {
173 ifp = lle->lle_tbl->llt_ifp;
174 CURVNET_SET(ifp->if_vnet);
176 if ((lle->la_flags & LLE_DELETED) == 0) {
179 if (lle->la_flags & LLE_VALID)
180 evt = LLENTRY_EXPIRED;
182 evt = LLENTRY_TIMEDOUT;
183 EVENTHANDLER_INVOKE(lle_event, lle, evt);
186 callout_stop(&lle->la_timer);
188 /* XXX: LOR avoidance. We still have ref on lle. */
193 /* Guard against race with other llentry_free(). */
194 if (lle->la_flags & LLE_LINKED) {
198 pkts_dropped = llentry_free(lle);
199 ARPSTAT_ADD(dropped, pkts_dropped);
201 LLE_FREE_LOCKED(lle);
203 IF_AFDATA_UNLOCK(ifp);
205 ARPSTAT_INC(timeouts);
211 * Broadcast an ARP request. Caller specifies:
212 * - arp header source ip address
213 * - arp header target ip address
214 * - arp header source ethernet address
217 arprequest(struct ifnet *ifp, const struct in_addr *sip,
218 const struct in_addr *tip, u_char *enaddr)
223 u_char *carpaddr = NULL;
227 * The caller did not supply a source address, try to find
228 * a compatible one among those assigned to this interface.
233 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
234 if (ifa->ifa_addr->sa_family != AF_INET)
238 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
240 sip = &IA_SIN(ifa)->sin_addr;
243 sip = &IA_SIN(ifa)->sin_addr;
246 if (0 == ((sip->s_addr ^ tip->s_addr) &
247 IA_MASKSIN(ifa)->sin_addr.s_addr))
248 break; /* found it. */
250 IF_ADDR_RUNLOCK(ifp);
252 printf("%s: cannot find matching address\n", __func__);
257 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
259 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
261 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
262 2*ifp->if_data.ifi_addrlen;
263 m->m_pkthdr.len = m->m_len;
264 MH_ALIGN(m, m->m_len);
265 ah = mtod(m, struct arphdr *);
266 bzero((caddr_t)ah, m->m_len);
268 mac_netinet_arp_send(ifp, m);
270 ah->ar_pro = htons(ETHERTYPE_IP);
271 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
272 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
273 ah->ar_op = htons(ARPOP_REQUEST);
274 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
275 bcopy(sip, ar_spa(ah), ah->ar_pln);
276 bcopy(tip, ar_tpa(ah), ah->ar_pln);
277 sa.sa_family = AF_ARP;
279 m->m_flags |= M_BCAST;
280 m_clrprotoflags(m); /* Avoid confusing lower layers. */
281 (*ifp->if_output)(ifp, m, &sa, NULL);
282 ARPSTAT_INC(txrequests);
286 * Resolve an IP address into an ethernet address.
288 * ifp is the interface we use
289 * rt0 is the route to the final destination (possibly useless)
290 * m is the mbuf. May be NULL if we don't have a packet.
291 * dst is the next hop,
292 * desten is where we want the address.
294 * On success, desten is filled in and the function returns 0;
295 * If the packet must be held pending resolution, we return EWOULDBLOCK
296 * On other errors, we return the corresponding error code.
297 * Note that m_freem() handles NULL.
300 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
301 const struct sockaddr *dst, u_char *desten, struct llentry **lle)
303 struct llentry *la = 0;
305 struct mbuf *curr = NULL;
306 struct mbuf *next = NULL;
311 if (m->m_flags & M_BCAST) {
314 ifp->if_broadcastaddr, ifp->if_addrlen);
317 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
319 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
324 IF_AFDATA_RLOCK(ifp);
325 la = lla_lookup(LLTABLE(ifp), flags, dst);
326 IF_AFDATA_RUNLOCK(ifp);
327 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
328 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
329 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
330 IF_AFDATA_WLOCK(ifp);
331 la = lla_lookup(LLTABLE(ifp), flags, dst);
332 IF_AFDATA_WUNLOCK(ifp);
335 if (flags & LLE_CREATE)
337 "arpresolve: can't allocate llinfo for %s on %s\n",
338 inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname);
343 if ((la->la_flags & LLE_VALID) &&
344 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
345 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
347 * If entry has an expiry time and it is approaching,
348 * see if we need to send an ARP request within this
349 * arpt_down interval.
351 if (!(la->la_flags & LLE_STATIC) &&
352 time_uptime + la->la_preempt > la->la_expire) {
353 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
362 if (la->la_flags & LLE_STATIC) { /* should not happen! */
363 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
364 inet_ntoa(SIN(dst)->sin_addr));
370 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
371 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
372 flags |= LLE_EXCLUSIVE;
377 * There is an arptab entry, but no ethernet address
378 * response yet. Add the mbuf to the list, dropping
379 * the oldest packet if we have exceeded the system
383 if (la->la_numheld >= V_arp_maxhold) {
384 if (la->la_hold != NULL) {
385 next = la->la_hold->m_nextpkt;
386 m_freem(la->la_hold);
389 ARPSTAT_INC(dropped);
392 if (la->la_hold != NULL) {
394 while (curr->m_nextpkt != NULL)
395 curr = curr->m_nextpkt;
400 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
401 flags &= ~LLE_EXCLUSIVE;
407 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
408 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
409 * if we have already sent arp_maxtries ARP requests. Retransmit the
410 * ARP request, but not faster than one request per second.
412 if (la->la_asked < V_arp_maxtries)
413 error = EWOULDBLOCK; /* First request. */
415 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
416 EHOSTUNREACH : EHOSTDOWN;
422 la->la_expire = time_uptime;
423 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
429 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
433 if (flags & LLE_EXCLUSIVE)
441 * Common length and type checks are done here,
442 * then the protocol-specific routine is called.
445 arpintr(struct mbuf *m)
449 if (m->m_len < sizeof(struct arphdr) &&
450 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
451 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n");
454 ar = mtod(m, struct arphdr *);
456 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
457 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
458 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
459 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 &&
460 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) {
461 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)"
462 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "",
463 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":",
464 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":");
469 if (m->m_len < arphdr_len(ar)) {
470 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
471 log(LOG_NOTICE, "arp: runt packet\n");
475 ar = mtod(m, struct arphdr *);
478 ARPSTAT_INC(received);
479 switch (ntohs(ar->ar_pro)) {
491 * ARP for Internet protocols on 10 Mb/s Ethernet.
492 * Algorithm is that given in RFC 826.
493 * In addition, a sanity check is performed on the sender
494 * protocol address, to catch impersonators.
495 * We no longer handle negotiations for use of trailer protocol:
496 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
497 * along with IP replies if we wanted trailers sent to us,
498 * and also sent them in response to IP replies.
499 * This allowed either end to announce the desire to receive
501 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
502 * but formerly didn't normally send requests.
504 static int log_arp_wrong_iface = 1;
505 static int log_arp_movements = 1;
506 static int log_arp_permanent_modify = 1;
507 static int allow_multicast = 0;
508 static struct timeval arp_lastlog;
509 static int arp_curpps;
510 static int arp_maxpps = 1;
512 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
513 &log_arp_wrong_iface, 0,
514 "log arp packets arriving on the wrong interface");
515 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
516 &log_arp_movements, 0,
517 "log arp replies from MACs different than the one in the cache");
518 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
519 &log_arp_permanent_modify, 0,
520 "log arp replies from MACs different than the one in the permanent arp entry");
521 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
522 &allow_multicast, 0, "accept multicast addresses");
523 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
524 CTLFLAG_RW, &arp_maxpps, 0,
525 "Maximum number of remotely triggered ARP messages that can be "
526 "logged per second");
528 #define ARP_LOG(pri, ...) do { \
529 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
530 log((pri), "arp: " __VA_ARGS__); \
534 in_arpinput(struct mbuf *m)
537 struct ifnet *ifp = m->m_pkthdr.rcvif;
538 struct llentry *la = NULL;
541 struct in_ifaddr *ia;
543 struct in_addr isaddr, itaddr, myaddr;
544 u_int8_t *enaddr = NULL;
547 int bridged = 0, is_bridge = 0;
549 struct sockaddr_in sin;
550 sin.sin_len = sizeof(struct sockaddr_in);
551 sin.sin_family = AF_INET;
552 sin.sin_addr.s_addr = 0;
556 if (ifp->if_type == IFT_BRIDGE)
559 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
560 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
561 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n");
565 ah = mtod(m, struct arphdr *);
567 * ARP is only for IPv4 so we can reject packets with
568 * a protocol length not equal to an IPv4 address.
570 if (ah->ar_pln != sizeof(struct in_addr)) {
571 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
572 sizeof(struct in_addr));
576 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
577 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
578 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
582 op = ntohs(ah->ar_op);
583 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
584 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
586 if (op == ARPOP_REPLY)
587 ARPSTAT_INC(rxreplies);
590 * For a bridge, we want to check the address irrespective
591 * of the receive interface. (This will change slightly
592 * when we have clusters of interfaces).
595 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
596 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
597 ia->ia_ifp == ifp) &&
598 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
599 (ia->ia_ifa.ifa_carp == NULL ||
600 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
601 ifa_ref(&ia->ia_ifa);
606 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
607 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
608 ia->ia_ifp == ifp) &&
609 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
610 ifa_ref(&ia->ia_ifa);
615 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
616 (ia->ia_ifp->if_bridge == ifp->if_softc && \
617 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
618 addr == ia->ia_addr.sin_addr.s_addr)
620 * Check the case when bridge shares its MAC address with
621 * some of its children, so packets are claimed by bridge
622 * itself (bridge_input() does it first), but they are really
623 * meant to be destined to the bridge member.
626 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
627 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
628 ifa_ref(&ia->ia_ifa);
635 #undef BDG_MEMBER_MATCHES_ARP
639 * No match, use the first inet address on the receive interface
640 * as a dummy address for the rest of the function.
643 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
644 if (ifa->ifa_addr->sa_family == AF_INET &&
645 (ifa->ifa_carp == NULL ||
646 (*carp_iamatch_p)(ifa, &enaddr))) {
649 IF_ADDR_RUNLOCK(ifp);
652 IF_ADDR_RUNLOCK(ifp);
655 * If bridging, fall back to using any inet address.
658 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
662 ifa_ref(&ia->ia_ifa);
666 enaddr = (u_int8_t *)IF_LLADDR(ifp);
667 carped = (ia->ia_ifa.ifa_carp != NULL);
668 myaddr = ia->ia_addr.sin_addr;
669 ifa_free(&ia->ia_ifa);
670 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
671 goto drop; /* it's from me, ignore it. */
672 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
673 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
674 "%s!\n", inet_ntoa(isaddr));
678 * Warn if another host is using the same IP address, but only if the
679 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
680 * case we suppress the warning to avoid false positive complaints of
681 * potential misconfiguration.
683 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
684 myaddr.s_addr != 0) {
685 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
686 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
687 inet_ntoa(isaddr), ifp->if_xname);
692 if (ifp->if_flags & IFF_STATICARP)
695 bzero(&sin, sizeof(sin));
696 sin.sin_len = sizeof(struct sockaddr_in);
697 sin.sin_family = AF_INET;
698 sin.sin_addr = isaddr;
699 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
700 flags |= LLE_EXCLUSIVE;
702 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
703 IF_AFDATA_UNLOCK(ifp);
705 /* the following is not an error when doing bridging */
706 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
707 if (log_arp_wrong_iface)
708 ARP_LOG(LOG_WARNING, "%s is on %s "
709 "but got reply from %*D on %s\n",
711 la->lle_tbl->llt_ifp->if_xname,
712 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
717 if ((la->la_flags & LLE_VALID) &&
718 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
719 if (la->la_flags & LLE_STATIC) {
721 if (log_arp_permanent_modify)
723 "%*D attempts to modify "
724 "permanent entry for %s on %s\n",
726 (u_char *)ar_sha(ah), ":",
727 inet_ntoa(isaddr), ifp->if_xname);
730 if (log_arp_movements) {
731 ARP_LOG(LOG_INFO, "%s moved from %*D "
735 (u_char *)&la->ll_addr, ":",
736 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
741 if (ifp->if_addrlen != ah->ar_hln) {
743 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
744 "i/f %d (ignored)\n", ifp->if_addrlen,
745 (u_char *) ar_sha(ah), ":", ah->ar_hln,
749 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
750 la->la_flags |= LLE_VALID;
752 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
754 if (!(la->la_flags & LLE_STATIC)) {
758 la->la_expire = time_uptime + V_arpt_keep;
759 canceled = callout_reset(&la->la_timer,
760 hz * V_arpt_keep, arptimer, la);
765 la->la_preempt = V_arp_maxtries;
767 * The packets are all freed within the call to the output
770 * NB: The lock MUST be released before the call to the
773 if (la->la_hold != NULL) {
774 struct mbuf *m_hold, *m_hold_next;
776 m_hold = la->la_hold;
779 memcpy(&sa, L3_ADDR(la), sizeof(sa));
781 for (; m_hold != NULL; m_hold = m_hold_next) {
782 m_hold_next = m_hold->m_nextpkt;
783 m_hold->m_nextpkt = NULL;
784 /* Avoid confusing lower layers. */
785 m_clrprotoflags(m_hold);
786 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
792 if (op != ARPOP_REQUEST)
794 ARPSTAT_INC(rxrequests);
796 if (itaddr.s_addr == myaddr.s_addr) {
797 /* Shortcut.. the receiving interface is the target. */
798 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
799 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
801 struct llentry *lle = NULL;
803 sin.sin_addr = itaddr;
804 IF_AFDATA_RLOCK(ifp);
805 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
806 IF_AFDATA_RUNLOCK(ifp);
808 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
809 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
810 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
820 sin.sin_addr = itaddr;
821 /* XXX MRT use table 0 for arp reply */
822 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
827 * Don't send proxies for nodes on the same interface
828 * as this one came out of, or we'll get into a fight
829 * over who claims what Ether address.
831 if (!rt->rt_ifp || rt->rt_ifp == ifp) {
837 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
838 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
841 * Also check that the node which sent the ARP packet
842 * is on the interface we expect it to be on. This
843 * avoids ARP chaos if an interface is connected to the
846 sin.sin_addr = isaddr;
848 /* XXX MRT use table 0 for arp checks */
849 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
852 if (rt->rt_ifp != ifp) {
853 ARP_LOG(LOG_INFO, "proxy: ignoring request"
854 " from %s via %s, expecting %s\n",
855 inet_ntoa(isaddr), ifp->if_xname,
856 rt->rt_ifp->if_xname);
863 printf("arp: proxying for %s\n", inet_ntoa(itaddr));
868 if (itaddr.s_addr == myaddr.s_addr &&
869 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
870 /* RFC 3927 link-local IPv4; always reply by broadcast. */
871 #ifdef DEBUG_LINKLOCAL
872 printf("arp: sending reply for link-local addr %s\n",
875 m->m_flags |= M_BCAST;
876 m->m_flags &= ~M_MCAST;
878 /* default behaviour; never reply by broadcast. */
879 m->m_flags &= ~(M_BCAST|M_MCAST);
881 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
882 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
883 ah->ar_op = htons(ARPOP_REPLY);
884 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
885 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
886 m->m_pkthdr.len = m->m_len;
887 m->m_pkthdr.rcvif = NULL;
888 sa.sa_family = AF_ARP;
890 m_clrprotoflags(m); /* Avoid confusing lower layers. */
891 (*ifp->if_output)(ifp, m, &sa, NULL);
892 ARPSTAT_INC(txreplies);
901 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
905 if (ifa->ifa_carp != NULL)
908 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
909 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
910 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
912 * interface address is considered static entry
913 * because the output of the arp utility shows
914 * that L2 entry as permanent
917 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
918 (struct sockaddr *)IA_SIN(ifa));
919 IF_AFDATA_UNLOCK(ifp);
921 log(LOG_INFO, "arp_ifinit: cannot create arp "
922 "entry for interface address\n");
926 ifa->ifa_rtrequest = NULL;
930 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
932 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
933 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
934 &IA_SIN(ifa)->sin_addr, enaddr);
935 ifa->ifa_rtrequest = NULL;
942 netisr_register(&arp_nh);
944 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);