1 /* SPDX-License-Identifier: BSD-2-Clause */
2 /*
3 * dhcpcd - ARP handler
4 * Copyright (c) 2006-2023 Roy Marples <roy@marples.name>
5 * All rights reserved
6
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/socket.h>
30 #include <sys/types.h>
31
32 #include <arpa/inet.h>
33
34 #include <net/if.h>
35 #include <netinet/in.h>
36 #include <netinet/if_ether.h>
37
38 #include <errno.h>
39 #include <stdlib.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 #define ELOOP_QUEUE ELOOP_ARP
45 #include "config.h"
46 #include "arp.h"
47 #include "bpf.h"
48 #include "ipv4.h"
49 #include "common.h"
50 #include "dhcpcd.h"
51 #include "eloop.h"
52 #include "if.h"
53 #include "if-options.h"
54 #include "ipv4ll.h"
55 #include "logerr.h"
56 #include "privsep.h"
57
58 #if defined(ARP)
59 #define ARP_LEN \
60 (FRAMEHDRLEN_MAX + \
61 sizeof(struct arphdr) + (2 * sizeof(uint32_t)) + (2 * HWADDR_LEN))
62
63 /* ARP debugging can be quite noisy. Enable this for more noise! */
64 //#define ARP_DEBUG
65
66 /* Assert the correct structure size for on wire */
67 __CTASSERT(sizeof(struct arphdr) == 8);
68
69 static ssize_t
arp_request(const struct arp_state * astate,const struct in_addr * sip)70 arp_request(const struct arp_state *astate,
71 const struct in_addr *sip)
72 {
73 const struct interface *ifp = astate->iface;
74 const struct in_addr *tip = &astate->addr;
75 uint8_t arp_buffer[ARP_LEN];
76 struct arphdr ar;
77 size_t len;
78 uint8_t *p;
79
80 ar.ar_hrd = htons(ifp->hwtype);
81 ar.ar_pro = htons(ETHERTYPE_IP);
82 ar.ar_hln = ifp->hwlen;
83 ar.ar_pln = sizeof(tip->s_addr);
84 ar.ar_op = htons(ARPOP_REQUEST);
85
86 p = arp_buffer;
87 len = 0;
88
89 #define CHECK(fun, b, l) \
90 do { \
91 if (len + (l) > sizeof(arp_buffer)) \
92 goto eexit; \
93 fun(p, (b), (l)); \
94 p += (l); \
95 len += (l); \
96 } while (/* CONSTCOND */ 0)
97 #define APPEND(b, l) CHECK(memcpy, b, l)
98 #define ZERO(l) CHECK(memset, 0, l)
99
100 APPEND(&ar, sizeof(ar));
101 APPEND(ifp->hwaddr, ifp->hwlen);
102 if (sip != NULL)
103 APPEND(&sip->s_addr, sizeof(sip->s_addr));
104 else
105 ZERO(sizeof(tip->s_addr));
106 ZERO(ifp->hwlen);
107 APPEND(&tip->s_addr, sizeof(tip->s_addr));
108
109 #ifdef PRIVSEP
110 if (ifp->ctx->options & DHCPCD_PRIVSEP)
111 return ps_bpf_sendarp(ifp, tip, arp_buffer, len);
112 #endif
113 /* Note that well formed ethernet will add extra padding
114 * to ensure that the packet is at least 60 bytes (64 including FCS). */
115 return bpf_send(astate->bpf, ETHERTYPE_ARP, arp_buffer, len);
116
117 eexit:
118 errno = ENOBUFS;
119 return -1;
120 }
121
122 static void
arp_report_conflicted(const struct arp_state * astate,const struct arp_msg * amsg)123 arp_report_conflicted(const struct arp_state *astate,
124 const struct arp_msg *amsg)
125 {
126 char abuf[HWADDR_LEN * 3];
127 char fbuf[HWADDR_LEN * 3];
128
129 if (amsg == NULL) {
130 logerrx("%s: DAD detected %s",
131 astate->iface->name, inet_ntoa(astate->addr));
132 return;
133 }
134
135 hwaddr_ntoa(amsg->sha, astate->iface->hwlen, abuf, sizeof(abuf));
136 if (bpf_frame_header_len(astate->iface) == 0) {
137 logwarnx("%s: %s claims %s",
138 astate->iface->name, abuf, inet_ntoa(astate->addr));
139 return;
140 }
141
142 logwarnx("%s: %s(%s) claims %s",
143 astate->iface->name, abuf,
144 hwaddr_ntoa(amsg->fsha, astate->iface->hwlen, fbuf, sizeof(fbuf)),
145 inet_ntoa(astate->addr));
146 }
147
148 static void
arp_found(struct arp_state * astate,const struct arp_msg * amsg)149 arp_found(struct arp_state *astate, const struct arp_msg *amsg)
150 {
151 struct interface *ifp;
152 struct ipv4_addr *ia;
153 #ifndef KERNEL_RFC5227
154 struct timespec now;
155 #endif
156
157 arp_report_conflicted(astate, amsg);
158 ifp = astate->iface;
159
160 /* If we haven't added the address we're doing a probe. */
161 ia = ipv4_iffindaddr(ifp, &astate->addr, NULL);
162 if (ia == NULL) {
163 if (astate->found_cb != NULL)
164 astate->found_cb(astate, amsg);
165 return;
166 }
167
168 #ifndef KERNEL_RFC5227
169 /* RFC 3927 Section 2.5 says a defence should
170 * broadcast an ARP announcement.
171 * Because the kernel will also unicast a reply to the
172 * hardware address which requested the IP address
173 * the other IPv4LL client will receieve two ARP
174 * messages.
175 * If another conflict happens within DEFEND_INTERVAL
176 * then we must drop our address and negotiate a new one. */
177 clock_gettime(CLOCK_MONOTONIC, &now);
178 if (timespecisset(&astate->defend) &&
179 eloop_timespec_diff(&now, &astate->defend, NULL) < DEFEND_INTERVAL)
180 logwarnx("%s: %d second defence failed for %s",
181 ifp->name, DEFEND_INTERVAL, inet_ntoa(astate->addr));
182 else if (arp_request(astate, &astate->addr) == -1)
183 logerr(__func__);
184 else {
185 logdebugx("%s: defended address %s",
186 ifp->name, inet_ntoa(astate->addr));
187 astate->defend = now;
188 return;
189 }
190 #endif
191
192 if (astate->defend_failed_cb != NULL)
193 astate->defend_failed_cb(astate);
194 }
195
196 static bool
arp_validate(const struct interface * ifp,struct arphdr * arp)197 arp_validate(const struct interface *ifp, struct arphdr *arp)
198 {
199
200 /* Address type must match */
201 if (arp->ar_hrd != htons(ifp->hwtype))
202 return false;
203
204 /* Protocol must be IP. */
205 if (arp->ar_pro != htons(ETHERTYPE_IP))
206 return false;
207
208 /* lladdr length matches */
209 if (arp->ar_hln != ifp->hwlen)
210 return false;
211
212 /* Protocol length must match in_addr_t */
213 if (arp->ar_pln != sizeof(in_addr_t))
214 return false;
215
216 /* Only these types are recognised */
217 if (arp->ar_op != htons(ARPOP_REPLY) &&
218 arp->ar_op != htons(ARPOP_REQUEST))
219 return false;
220
221 return true;
222 }
223
224 void
arp_packet(struct interface * ifp,uint8_t * data,size_t len,unsigned int bpf_flags)225 arp_packet(struct interface *ifp, uint8_t *data, size_t len,
226 unsigned int bpf_flags)
227 {
228 size_t fl = bpf_frame_header_len(ifp), falen;
229 const struct interface *ifn;
230 struct arphdr ar;
231 struct arp_msg arm;
232 const struct iarp_state *state;
233 struct arp_state *astate, *astaten;
234 uint8_t *hw_s, *hw_t;
235 #ifndef KERNEL_RFC5227
236 bool is_probe;
237 #endif /* KERNEL_RFC5227 */
238
239 /* Copy the frame header source and destination out */
240 memset(&arm, 0, sizeof(arm));
241 if (fl != 0) {
242 hw_s = bpf_frame_header_src(ifp, data, &falen);
243 if (hw_s != NULL && falen <= sizeof(arm.fsha))
244 memcpy(arm.fsha, hw_s, falen);
245 hw_t = bpf_frame_header_dst(ifp, data, &falen);
246 if (hw_t != NULL && falen <= sizeof(arm.ftha))
247 memcpy(arm.ftha, hw_t, falen);
248
249 /* Skip past the frame header */
250 data += fl;
251 len -= fl;
252 }
253
254 /* We must have a full ARP header */
255 if (len < sizeof(ar))
256 return;
257 memcpy(&ar, data, sizeof(ar));
258
259 if (!arp_validate(ifp, &ar)) {
260 #ifdef BPF_DEBUG
261 logerrx("%s: ARP BPF validation failure", ifp->name);
262 #endif
263 return;
264 }
265
266 /* Get pointers to the hardware addresses */
267 hw_s = data + sizeof(ar);
268 hw_t = hw_s + ar.ar_hln + ar.ar_pln;
269 /* Ensure we got all the data */
270 if ((size_t)((hw_t + ar.ar_hln + ar.ar_pln) - data) > len)
271 return;
272 /* Ignore messages from ourself */
273 TAILQ_FOREACH(ifn, ifp->ctx->ifaces, next) {
274 if (ar.ar_hln == ifn->hwlen &&
275 memcmp(hw_s, ifn->hwaddr, ifn->hwlen) == 0)
276 break;
277 }
278 if (ifn) {
279 #ifdef ARP_DEBUG
280 logdebugx("%s: ignoring ARP from self", ifp->name);
281 #endif
282 return;
283 }
284 /* Copy out the HW and IP addresses */
285 memcpy(&arm.sha, hw_s, ar.ar_hln);
286 memcpy(&arm.sip.s_addr, hw_s + ar.ar_hln, ar.ar_pln);
287 memcpy(&arm.tha, hw_t, ar.ar_hln);
288 memcpy(&arm.tip.s_addr, hw_t + ar.ar_hln, ar.ar_pln);
289
290 #ifndef KERNEL_RFC5227
291 /* During ARP probe the 'sender hardware address' MUST contain the hardware
292 * address of the interface sending the packet. RFC5227, 1.1 */
293 is_probe = ar.ar_op == htons(ARPOP_REQUEST) && IN_IS_ADDR_UNSPECIFIED(&arm.sip) &&
294 bpf_flags & BPF_BCAST;
295 if (is_probe && falen > 0 && (falen != ar.ar_hln ||
296 memcmp(&arm.sha, &arm.fsha, ar.ar_hln))) {
297 char abuf[HWADDR_LEN * 3];
298 char fbuf[HWADDR_LEN * 3];
299 hwaddr_ntoa(&arm.sha, ar.ar_hln, abuf, sizeof(abuf));
300 hwaddr_ntoa(&arm.fsha, falen, fbuf, sizeof(fbuf));
301 logwarnx("%s: invalid ARP probe, sender hw address mismatch (%s, %s)",
302 ifp->name, abuf, fbuf);
303 return;
304 }
305 #endif /* KERNEL_RFC5227 */
306
307 /* Match the ARP probe to our states.
308 * Ignore Unicast Poll, RFC1122. */
309 state = ARP_CSTATE(ifp);
310 if (state == NULL)
311 return;
312 TAILQ_FOREACH_SAFE(astate, &state->arp_states, next, astaten) {
313 if (IN_ARE_ADDR_EQUAL(&arm.sip, &astate->addr) ||
314 (IN_IS_ADDR_UNSPECIFIED(&arm.sip) &&
315 IN_ARE_ADDR_EQUAL(&arm.tip, &astate->addr) &&
316 bpf_flags & BPF_BCAST))
317 arp_found(astate, &arm);
318 }
319 }
320
321 static void
arp_read(void * arg,unsigned short events)322 arp_read(void *arg, unsigned short events)
323 {
324 struct arp_state *astate = arg;
325 struct bpf *bpf = astate->bpf;
326 struct interface *ifp = astate->iface;
327 uint8_t buf[ARP_LEN];
328 ssize_t bytes;
329 struct in_addr addr = astate->addr;
330
331 if (events != ELE_READ)
332 logerrx("%s: unexpected event 0x%04x", __func__, events);
333
334 /* Some RAW mechanisms are generic file descriptors, not sockets.
335 * This means we have no kernel call to just get one packet,
336 * so we have to process the entire buffer. */
337 bpf->bpf_flags &= ~BPF_EOF;
338 while (!(bpf->bpf_flags & BPF_EOF)) {
339 bytes = bpf_read(bpf, buf, sizeof(buf));
340 if (bytes == -1) {
341 logerr("%s: %s", __func__, ifp->name);
342 arp_free(astate);
343 return;
344 }
345 arp_packet(ifp, buf, (size_t)bytes, bpf->bpf_flags);
346 /* Check we still have a state after processing. */
347 if ((astate = arp_find(ifp, &addr)) == NULL)
348 break;
349 if ((bpf = astate->bpf) == NULL)
350 break;
351 }
352 }
353
354 static void
arp_probed(void * arg)355 arp_probed(void *arg)
356 {
357 struct arp_state *astate = arg;
358
359 timespecclear(&astate->defend);
360 astate->not_found_cb(astate);
361 }
362
363 static void
arp_probe1(void * arg)364 arp_probe1(void *arg)
365 {
366 struct arp_state *astate = arg;
367 struct interface *ifp = astate->iface;
368 unsigned int delay;
369
370 if (++astate->probes < PROBE_NUM) {
371 delay = (PROBE_MIN * MSEC_PER_SEC) +
372 (arc4random_uniform(
373 (PROBE_MAX - PROBE_MIN) * MSEC_PER_SEC));
374 eloop_timeout_add_msec(ifp->ctx->eloop, delay, arp_probe1, astate);
375 } else {
376 delay = ANNOUNCE_WAIT * MSEC_PER_SEC;
377 eloop_timeout_add_msec(ifp->ctx->eloop, delay, arp_probed, astate);
378 }
379 logdebugx("%s: ARP probing %s (%d of %d), next in %0.1f seconds",
380 ifp->name, inet_ntoa(astate->addr),
381 astate->probes ? astate->probes : PROBE_NUM, PROBE_NUM,
382 (float)delay / MSEC_PER_SEC);
383 if (arp_request(astate, NULL) == -1)
384 logerr(__func__);
385 }
386
387 void
arp_probe(struct arp_state * astate)388 arp_probe(struct arp_state *astate)
389 {
390
391 astate->probes = 0;
392 logdebugx("%s: probing for %s",
393 astate->iface->name, inet_ntoa(astate->addr));
394 arp_probe1(astate);
395 }
396 #endif /* ARP */
397
398 struct arp_state *
arp_find(struct interface * ifp,const struct in_addr * addr)399 arp_find(struct interface *ifp, const struct in_addr *addr)
400 {
401 struct iarp_state *state;
402 struct arp_state *astate;
403
404 if ((state = ARP_STATE(ifp)) == NULL)
405 goto out;
406 TAILQ_FOREACH(astate, &state->arp_states, next) {
407 if (astate->addr.s_addr == addr->s_addr && astate->iface == ifp)
408 return astate;
409 }
410 out:
411 errno = ESRCH;
412 return NULL;
413 }
414
415 static void
arp_announced(void * arg)416 arp_announced(void *arg)
417 {
418 struct arp_state *astate = arg;
419
420 if (astate->announced_cb) {
421 astate->announced_cb(astate);
422 return;
423 }
424
425 /* Keep the ARP state open to handle ongoing ACD. */
426 }
427
428 static void
arp_announce1(void * arg)429 arp_announce1(void *arg)
430 {
431 struct arp_state *astate = arg;
432 struct interface *ifp = astate->iface;
433 struct ipv4_addr *ia;
434
435 if (++astate->claims < ANNOUNCE_NUM)
436 logdebugx("%s: ARP announcing %s (%d of %d), "
437 "next in %d.0 seconds",
438 ifp->name, inet_ntoa(astate->addr),
439 astate->claims, ANNOUNCE_NUM, ANNOUNCE_WAIT);
440 else
441 logdebugx("%s: ARP announcing %s (%d of %d)",
442 ifp->name, inet_ntoa(astate->addr),
443 astate->claims, ANNOUNCE_NUM);
444
445 /* The kernel will send a Gratuitous ARP for newly added addresses.
446 * So we can avoid sending the same.
447 * Linux is special and doesn't send one. */
448 ia = ipv4_iffindaddr(ifp, &astate->addr, NULL);
449 #ifndef __linux__
450 if (astate->claims == 1 && ia != NULL && ia->flags & IPV4_AF_NEW)
451 goto skip_request;
452 #endif
453
454 if (arp_request(astate, &astate->addr) == -1)
455 logerr(__func__);
456
457 #ifndef __linux__
458 skip_request:
459 #endif
460 /* No longer a new address. */
461 if (ia != NULL)
462 ia->flags |= ~IPV4_AF_NEW;
463
464 eloop_timeout_add_sec(ifp->ctx->eloop, ANNOUNCE_WAIT,
465 astate->claims < ANNOUNCE_NUM ? arp_announce1 : arp_announced,
466 astate);
467 }
468
469 static void
arp_announce(struct arp_state * astate)470 arp_announce(struct arp_state *astate)
471 {
472 struct iarp_state *state;
473 struct interface *ifp;
474 struct arp_state *a2;
475 int r;
476
477 /* Cancel any other ARP announcements for this address. */
478 TAILQ_FOREACH(ifp, astate->iface->ctx->ifaces, next) {
479 state = ARP_STATE(ifp);
480 if (state == NULL)
481 continue;
482 TAILQ_FOREACH(a2, &state->arp_states, next) {
483 if (astate == a2 ||
484 a2->addr.s_addr != astate->addr.s_addr)
485 continue;
486 r = eloop_timeout_delete(a2->iface->ctx->eloop,
487 a2->claims < ANNOUNCE_NUM
488 ? arp_announce1 : arp_announced,
489 a2);
490 if (r == -1)
491 logerr(__func__);
492 else if (r != 0) {
493 logdebugx("%s: ARP announcement "
494 "of %s cancelled",
495 a2->iface->name,
496 inet_ntoa(a2->addr));
497 arp_announced(a2);
498 }
499 }
500 }
501
502 astate->claims = 0;
503 arp_announce1(astate);
504 }
505
506 struct arp_state *
arp_ifannounceaddr(struct interface * ifp,const struct in_addr * ia)507 arp_ifannounceaddr(struct interface *ifp, const struct in_addr *ia)
508 {
509 struct arp_state *astate;
510
511 if (ifp->flags & IFF_NOARP || !(ifp->options->options & DHCPCD_ARP))
512 return NULL;
513
514 astate = arp_find(ifp, ia);
515 if (astate == NULL) {
516 astate = arp_new(ifp, ia);
517 if (astate == NULL)
518 return NULL;
519 astate->announced_cb = arp_free;
520 }
521 arp_announce(astate);
522 return astate;
523 }
524
525 struct arp_state *
arp_announceaddr(struct dhcpcd_ctx * ctx,const struct in_addr * ia)526 arp_announceaddr(struct dhcpcd_ctx *ctx, const struct in_addr *ia)
527 {
528 struct interface *ifp, *iff = NULL;
529 struct ipv4_addr *iap;
530
531 TAILQ_FOREACH(ifp, ctx->ifaces, next) {
532 if (!ifp->active || !if_is_link_up(ifp))
533 continue;
534 iap = ipv4_iffindaddr(ifp, ia, NULL);
535 if (iap == NULL)
536 continue;
537 #ifdef IN_IFF_NOTUSEABLE
538 if (iap->addr_flags & IN_IFF_NOTUSEABLE)
539 continue;
540 #endif
541 if (iff != NULL && iff->metric < ifp->metric)
542 continue;
543 iff = ifp;
544 }
545 if (iff == NULL)
546 return NULL;
547
548 return arp_ifannounceaddr(iff, ia);
549 }
550
551 struct arp_state *
arp_new(struct interface * ifp,const struct in_addr * addr)552 arp_new(struct interface *ifp, const struct in_addr *addr)
553 {
554 struct iarp_state *state;
555 struct arp_state *astate;
556
557 if ((state = ARP_STATE(ifp)) == NULL) {
558 ifp->if_data[IF_DATA_ARP] = malloc(sizeof(*state));
559 state = ARP_STATE(ifp);
560 if (state == NULL) {
561 logerr(__func__);
562 return NULL;
563 }
564 TAILQ_INIT(&state->arp_states);
565 } else {
566 if ((astate = arp_find(ifp, addr)) != NULL)
567 return astate;
568 }
569
570 if ((astate = calloc(1, sizeof(*astate))) == NULL) {
571 logerr(__func__);
572 return NULL;
573 }
574 astate->iface = ifp;
575 astate->addr = *addr;
576
577 #ifdef PRIVSEP
578 if (IN_PRIVSEP(ifp->ctx)) {
579 if (ps_bpf_openarp(ifp, addr) == -1) {
580 logerr(__func__);
581 free(astate);
582 return NULL;
583 }
584 } else
585 #endif
586 {
587 astate->bpf = bpf_open(ifp, bpf_arp, addr);
588 if (astate->bpf == NULL) {
589 logerr(__func__);
590 free(astate);
591 return NULL;
592 }
593 if (eloop_event_add(ifp->ctx->eloop, astate->bpf->bpf_fd, ELE_READ,
594 arp_read, astate) == -1)
595 logerr("%s: eloop_event_add", __func__);
596 }
597
598
599 state = ARP_STATE(ifp);
600 TAILQ_INSERT_TAIL(&state->arp_states, astate, next);
601 return astate;
602 }
603
604 void
arp_free(struct arp_state * astate)605 arp_free(struct arp_state *astate)
606 {
607 struct interface *ifp;
608 struct dhcpcd_ctx *ctx;
609 struct iarp_state *state;
610
611 if (astate == NULL)
612 return;
613
614 ifp = astate->iface;
615 ctx = ifp->ctx;
616 eloop_timeout_delete(ctx->eloop, NULL, astate);
617
618 state = ARP_STATE(ifp);
619 TAILQ_REMOVE(&state->arp_states, astate, next);
620 if (astate->free_cb)
621 astate->free_cb(astate);
622
623 #ifdef PRIVSEP
624 if (IN_PRIVSEP(ctx) && ps_bpf_closearp(ifp, &astate->addr) == -1)
625 logerr(__func__);
626 #endif
627 if (astate->bpf != NULL) {
628 eloop_event_delete(ctx->eloop, astate->bpf->bpf_fd);
629 bpf_close(astate->bpf);
630 }
631
632 free(astate);
633
634 if (TAILQ_FIRST(&state->arp_states) == NULL) {
635 free(state);
636 ifp->if_data[IF_DATA_ARP] = NULL;
637 }
638 }
639
640 void
arp_freeaddr(struct interface * ifp,const struct in_addr * ia)641 arp_freeaddr(struct interface *ifp, const struct in_addr *ia)
642 {
643 struct arp_state *astate;
644
645 astate = arp_find(ifp, ia);
646 arp_free(astate);
647 }
648
649 void
arp_drop(struct interface * ifp)650 arp_drop(struct interface *ifp)
651 {
652 struct iarp_state *state;
653 struct arp_state *astate;
654
655 while ((state = ARP_STATE(ifp)) != NULL &&
656 (astate = TAILQ_FIRST(&state->arp_states)) != NULL)
657 arp_free(astate);
658 }
659