if_ethersubr.c revision 1.15 1 /* $NetBSD: if_ethersubr.c,v 1.15 1995/09/29 03:37:43 phil Exp $ */
2
3 /*
4 * Copyright (c) 1982, 1989, 1993
5 * The Regents of the University of California. 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 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#)if_ethersubr.c 8.1 (Berkeley) 6/10/93
36 */
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/kernel.h>
41 #include <sys/malloc.h>
42 #include <sys/mbuf.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
45 #include <sys/ioctl.h>
46 #include <sys/errno.h>
47 #include <sys/syslog.h>
48
49 #include <machine/cpu.h>
50
51 #include <net/if.h>
52 #include <net/netisr.h>
53 #include <net/route.h>
54 #include <net/if_llc.h>
55 #include <net/if_dl.h>
56 #include <net/if_types.h>
57
58 #include <netinet/in.h>
59 #ifdef INET
60 #include <netinet/in_var.h>
61 #endif
62 #include <netinet/if_ether.h>
63
64 #ifdef NS
65 #include <netns/ns.h>
66 #include <netns/ns_if.h>
67 #endif
68
69 #ifdef ISO
70 #include <netiso/argo_debug.h>
71 #include <netiso/iso.h>
72 #include <netiso/iso_var.h>
73 #include <netiso/iso_snpac.h>
74 #endif
75
76 #ifdef LLC
77 #include <netccitt/dll.h>
78 #include <netccitt/llc_var.h>
79 #endif
80
81 #if defined(LLC) && defined(CCITT)
82 extern struct ifqueue pkintrq;
83 #endif
84
85 u_char etherbroadcastaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
86 #define senderr(e) { error = (e); goto bad;}
87
88 /*
89 * Ethernet output routine.
90 * Encapsulate a packet of type family for the local net.
91 * Use trailer local net encapsulation if enough data in first
92 * packet leaves a multiple of 512 bytes of data in remainder.
93 * Assumes that ifp is actually pointer to arpcom structure.
94 */
95 int
96 ether_output(ifp, m0, dst, rt0)
97 register struct ifnet *ifp;
98 struct mbuf *m0;
99 struct sockaddr *dst;
100 struct rtentry *rt0;
101 {
102 u_int16_t etype;
103 int s, error = 0;
104 u_char edst[6];
105 register struct mbuf *m = m0;
106 register struct rtentry *rt;
107 struct mbuf *mcopy = (struct mbuf *)0;
108 register struct ether_header *eh;
109 struct arpcom *ac = (struct arpcom *)ifp;
110
111 if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
112 senderr(ENETDOWN);
113 ifp->if_lastchange = time;
114 if (rt = rt0) {
115 if ((rt->rt_flags & RTF_UP) == 0) {
116 if (rt0 = rt = rtalloc1(dst, 1))
117 rt->rt_refcnt--;
118 else
119 senderr(EHOSTUNREACH);
120 }
121 if (rt->rt_flags & RTF_GATEWAY) {
122 if (rt->rt_gwroute == 0)
123 goto lookup;
124 if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
125 rtfree(rt); rt = rt0;
126 lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
127 if ((rt = rt->rt_gwroute) == 0)
128 senderr(EHOSTUNREACH);
129 }
130 }
131 if (rt->rt_flags & RTF_REJECT)
132 if (rt->rt_rmx.rmx_expire == 0 ||
133 time.tv_sec < rt->rt_rmx.rmx_expire)
134 senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
135 }
136 switch (dst->sa_family) {
137
138 #ifdef INET
139 case AF_INET:
140 if (!arpresolve(ac, rt, m, dst, edst))
141 return (0); /* if not yet resolved */
142 /* If broadcasting on a simplex interface, loopback a copy */
143 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
144 mcopy = m_copy(m, 0, (int)M_COPYALL);
145 etype = ETHERTYPE_IP;
146 break;
147 #endif
148 #ifdef NS
149 case AF_NS:
150 etype = ETHERTYPE_NS;
151 bcopy((caddr_t)&(((struct sockaddr_ns *)dst)->sns_addr.x_host),
152 (caddr_t)edst, sizeof (edst));
153 if (!bcmp((caddr_t)edst, (caddr_t)&ns_thishost, sizeof(edst)))
154 return (looutput(ifp, m, dst, rt));
155 /* If broadcasting on a simplex interface, loopback a copy */
156 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
157 mcopy = m_copy(m, 0, (int)M_COPYALL);
158 break;
159 #endif
160 #ifdef ISO
161 case AF_ISO: {
162 int snpalen;
163 struct llc *l;
164 register struct sockaddr_dl *sdl;
165
166 if (rt && (sdl = (struct sockaddr_dl *)rt->rt_gateway) &&
167 sdl->sdl_family == AF_LINK && sdl->sdl_alen > 0) {
168 bcopy(LLADDR(sdl), (caddr_t)edst, sizeof(edst));
169 } else if (error =
170 iso_snparesolve(ifp, (struct sockaddr_iso *)dst,
171 (char *)edst, &snpalen))
172 goto bad; /* Not Resolved */
173 /* If broadcasting on a simplex interface, loopback a copy */
174 if (*edst & 1)
175 m->m_flags |= (M_BCAST|M_MCAST);
176 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX) &&
177 (mcopy = m_copy(m, 0, (int)M_COPYALL))) {
178 M_PREPEND(mcopy, sizeof (*eh), M_DONTWAIT);
179 if (mcopy) {
180 eh = mtod(mcopy, struct ether_header *);
181 bcopy((caddr_t)edst,
182 (caddr_t)eh->ether_dhost, sizeof (edst));
183 bcopy((caddr_t)ac->ac_enaddr,
184 (caddr_t)eh->ether_shost, sizeof (edst));
185 }
186 }
187 M_PREPEND(m, 3, M_DONTWAIT);
188 if (m == NULL)
189 return (0);
190 etype = m->m_pkthdr.len;
191 l = mtod(m, struct llc *);
192 l->llc_dsap = l->llc_ssap = LLC_ISO_LSAP;
193 l->llc_control = LLC_UI;
194 IFDEBUG(D_ETHER)
195 int i;
196 printf("unoutput: sending pkt to: ");
197 for (i=0; i<6; i++)
198 printf("%x ", edst[i] & 0xff);
199 printf("\n");
200 ENDDEBUG
201 } break;
202 #endif /* ISO */
203 #ifdef LLC
204 /* case AF_NSAP: */
205 case AF_CCITT: {
206 register struct sockaddr_dl *sdl =
207 (struct sockaddr_dl *) rt -> rt_gateway;
208
209 if (sdl && sdl->sdl_family == AF_LINK
210 && sdl->sdl_alen > 0) {
211 bcopy(LLADDR(sdl), (char *)edst,
212 sizeof(edst));
213 } else goto bad; /* Not a link interface ? Funny ... */
214 if ((ifp->if_flags & IFF_SIMPLEX) && (*edst & 1) &&
215 (mcopy = m_copy(m, 0, (int)M_COPYALL))) {
216 M_PREPEND(mcopy, sizeof (*eh), M_DONTWAIT);
217 if (mcopy) {
218 eh = mtod(mcopy, struct ether_header *);
219 bcopy((caddr_t)edst,
220 (caddr_t)eh->ether_dhost, sizeof (edst));
221 bcopy((caddr_t)ac->ac_enaddr,
222 (caddr_t)eh->ether_shost, sizeof (edst));
223 }
224 }
225 etype = m->m_pkthdr.len;
226 #ifdef LLC_DEBUG
227 {
228 int i;
229 register struct llc *l = mtod(m, struct llc *);
230
231 printf("ether_output: sending LLC2 pkt to: ");
232 for (i=0; i<6; i++)
233 printf("%x ", edst[i] & 0xff);
234 printf(" len 0x%x dsap 0x%x ssap 0x%x control 0x%x\n",
235 etype & 0xff, l->llc_dsap & 0xff, l->llc_ssap &0xff,
236 l->llc_control & 0xff);
237
238 }
239 #endif /* LLC_DEBUG */
240 } break;
241 #endif /* LLC */
242
243 case AF_UNSPEC:
244 eh = (struct ether_header *)dst->sa_data;
245 bcopy((caddr_t)eh->ether_dhost, (caddr_t)edst, sizeof (edst));
246 /* AF_UNSPEC doesn't swap the byte order of the ether_type. */
247 etype = ntohs(eh->ether_type);
248 break;
249
250 default:
251 printf("%s%d: can't handle af%d\n", ifp->if_name, ifp->if_unit,
252 dst->sa_family);
253 senderr(EAFNOSUPPORT);
254 }
255
256
257 if (mcopy)
258 (void) looutput(ifp, mcopy, dst, rt);
259 /*
260 * Add local net header. If no space in first mbuf,
261 * allocate another.
262 */
263 M_PREPEND(m, sizeof (struct ether_header), M_DONTWAIT);
264 if (m == 0)
265 senderr(ENOBUFS);
266 eh = mtod(m, struct ether_header *);
267 etype = htons(etype);
268 bcopy((caddr_t)&etype,(caddr_t)&eh->ether_type,
269 sizeof(eh->ether_type));
270 bcopy((caddr_t)edst, (caddr_t)eh->ether_dhost, sizeof (edst));
271 bcopy((caddr_t)ac->ac_enaddr, (caddr_t)eh->ether_shost,
272 sizeof(eh->ether_shost));
273 s = splimp();
274 /*
275 * Queue message on interface, and start output if interface
276 * not yet active.
277 */
278 if (IF_QFULL(&ifp->if_snd)) {
279 IF_DROP(&ifp->if_snd);
280 splx(s);
281 senderr(ENOBUFS);
282 }
283 ifp->if_obytes += m->m_pkthdr.len;
284 IF_ENQUEUE(&ifp->if_snd, m);
285 if ((ifp->if_flags & IFF_OACTIVE) == 0)
286 (*ifp->if_start)(ifp);
287 splx(s);
288 if (m->m_flags & M_MCAST)
289 ifp->if_omcasts++;
290 return (error);
291
292 bad:
293 if (m)
294 m_freem(m);
295 return (error);
296 }
297
298 /*
299 * Process a received Ethernet packet;
300 * the packet is in the mbuf chain m without
301 * the ether header, which is provided separately.
302 */
303 void
304 ether_input(ifp, eh, m)
305 struct ifnet *ifp;
306 register struct ether_header *eh;
307 struct mbuf *m;
308 {
309 register struct ifqueue *inq;
310 register struct llc *l;
311 u_int16_t etype;
312 struct arpcom *ac = (struct arpcom *)ifp;
313 int s;
314
315 if ((ifp->if_flags & IFF_UP) == 0) {
316 m_freem(m);
317 return;
318 }
319 ifp->if_lastchange = time;
320 ifp->if_ibytes += m->m_pkthdr.len + sizeof (*eh);
321 if (eh->ether_dhost[0] & 1) {
322 if (bcmp((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
323 sizeof(etherbroadcastaddr)) == 0)
324 m->m_flags |= M_BCAST;
325 else
326 m->m_flags |= M_MCAST;
327 }
328 if (m->m_flags & (M_BCAST|M_MCAST))
329 ifp->if_imcasts++;
330
331 etype = ntohs(eh->ether_type);
332 switch (etype) {
333 #ifdef INET
334 case ETHERTYPE_IP:
335 schednetisr(NETISR_IP);
336 inq = &ipintrq;
337 break;
338
339 case ETHERTYPE_ARP:
340 schednetisr(NETISR_ARP);
341 inq = &arpintrq;
342 break;
343
344 case ETHERTYPE_REVARP:
345 revarpinput(m); /* XXX queue? */
346 return;
347 #endif
348 #ifdef NS
349 case ETHERTYPE_NS:
350 schednetisr(NETISR_NS);
351 inq = &nsintrq;
352 break;
353
354 #endif
355 default:
356 #if defined (ISO) || defined (LLC)
357 if (etype > ETHERMTU)
358 goto dropanyway;
359 l = mtod(m, struct llc *);
360 switch (l->llc_dsap) {
361 #ifdef ISO
362 case LLC_ISO_LSAP:
363 switch (l->llc_control) {
364 case LLC_UI:
365 /* LLC_UI_P forbidden in class 1 service */
366 if ((l->llc_dsap == LLC_ISO_LSAP) &&
367 (l->llc_ssap == LLC_ISO_LSAP)) {
368 /* LSAP for ISO */
369 if (m->m_pkthdr.len > etype)
370 m_adj(m, etype - m->m_pkthdr.len);
371 m->m_data += 3; /* XXX */
372 m->m_len -= 3; /* XXX */
373 m->m_pkthdr.len -= 3; /* XXX */
374 M_PREPEND(m, sizeof *eh, M_DONTWAIT);
375 if (m == 0)
376 return;
377 *mtod(m, struct ether_header *) = *eh;
378 IFDEBUG(D_ETHER)
379 printf("clnp packet");
380 ENDDEBUG
381 schednetisr(NETISR_ISO);
382 inq = &clnlintrq;
383 break;
384 }
385 goto dropanyway;
386
387 case LLC_XID:
388 case LLC_XID_P:
389 if(m->m_len < 6)
390 goto dropanyway;
391 l->llc_window = 0;
392 l->llc_fid = 9;
393 l->llc_class = 1;
394 l->llc_dsap = l->llc_ssap = 0;
395 /* Fall through to */
396 case LLC_TEST:
397 case LLC_TEST_P:
398 {
399 struct sockaddr sa;
400 register struct ether_header *eh2;
401 int i;
402 u_char c = l->llc_dsap;
403
404 l->llc_dsap = l->llc_ssap;
405 l->llc_ssap = c;
406 if (m->m_flags & (M_BCAST | M_MCAST))
407 bcopy((caddr_t)ac->ac_enaddr,
408 (caddr_t)eh->ether_dhost, 6);
409 sa.sa_family = AF_UNSPEC;
410 sa.sa_len = sizeof(sa);
411 eh2 = (struct ether_header *)sa.sa_data;
412 for (i = 0; i < 6; i++) {
413 eh2->ether_shost[i] = c = eh->ether_dhost[i];
414 eh2->ether_dhost[i] =
415 eh->ether_dhost[i] = eh->ether_shost[i];
416 eh->ether_shost[i] = c;
417 }
418 ifp->if_output(ifp, m, &sa, NULL);
419 return;
420 }
421 default:
422 m_freem(m);
423 return;
424 }
425 break;
426 #endif /* ISO */
427 #ifdef LLC
428 case LLC_X25_LSAP:
429 {
430 if (m->m_pkthdr.len > etype)
431 m_adj(m, etype - m->m_pkthdr.len);
432 M_PREPEND(m, sizeof(struct sdl_hdr) , M_DONTWAIT);
433 if (m == 0)
434 return;
435 if ( !sdl_sethdrif(ifp, eh->ether_shost, LLC_X25_LSAP,
436 eh->ether_dhost, LLC_X25_LSAP, 6,
437 mtod(m, struct sdl_hdr *)))
438 panic("ETHER cons addr failure");
439 mtod(m, struct sdl_hdr *)->sdlhdr_len = etype;
440 #ifdef LLC_DEBUG
441 printf("llc packet\n");
442 #endif /* LLC_DEBUG */
443 schednetisr(NETISR_CCITT);
444 inq = &llcintrq;
445 break;
446 }
447 #endif /* LLC */
448 dropanyway:
449 default:
450 m_freem(m);
451 return;
452 }
453 #else /* ISO || LLC */
454 m_freem(m);
455 return;
456 #endif /* ISO || LLC */
457 }
458
459 s = splimp();
460 if (IF_QFULL(inq)) {
461 IF_DROP(inq);
462 m_freem(m);
463 } else
464 IF_ENQUEUE(inq, m);
465 splx(s);
466 }
467
468 /*
469 * Convert Ethernet address to printable (loggable) representation.
470 */
471 static char digits[] = "0123456789abcdef";
472 char *
473 ether_sprintf(ap)
474 register u_char *ap;
475 {
476 register i;
477 static char etherbuf[18];
478 register char *cp = etherbuf;
479
480 for (i = 0; i < 6; i++) {
481 *cp++ = digits[*ap >> 4];
482 *cp++ = digits[*ap++ & 0xf];
483 *cp++ = ':';
484 }
485 *--cp = 0;
486 return (etherbuf);
487 }
488
489 /*
490 * Perform common duties while attaching to interface list
491 */
492 void
493 ether_ifattach(ifp)
494 register struct ifnet *ifp;
495 {
496 register struct ifaddr *ifa;
497 register struct sockaddr_dl *sdl;
498
499 ifp->if_type = IFT_ETHER;
500 ifp->if_addrlen = 6;
501 ifp->if_hdrlen = 14;
502 ifp->if_mtu = ETHERMTU;
503 ifp->if_output = ether_output;
504 for (ifa = ifp->if_addrlist.tqh_first; ifa != 0;
505 ifa = ifa->ifa_list.tqe_next)
506 if ((sdl = (struct sockaddr_dl *)ifa->ifa_addr) &&
507 sdl->sdl_family == AF_LINK) {
508 sdl->sdl_type = IFT_ETHER;
509 sdl->sdl_alen = ifp->if_addrlen;
510 bcopy((caddr_t)((struct arpcom *)ifp)->ac_enaddr,
511 LLADDR(sdl), ifp->if_addrlen);
512 break;
513 }
514 LIST_INIT(&((struct arpcom *)ifp)->ac_multiaddrs);
515 }
516
517 u_char ether_ipmulticast_min[6] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0x00 };
518 u_char ether_ipmulticast_max[6] = { 0x01, 0x00, 0x5e, 0x7f, 0xff, 0xff };
519 /*
520 * Add an Ethernet multicast address or range of addresses to the list for a
521 * given interface.
522 */
523 int
524 ether_addmulti(ifr, ac)
525 struct ifreq *ifr;
526 register struct arpcom *ac;
527 {
528 register struct ether_multi *enm;
529 struct sockaddr_in *sin;
530 u_char addrlo[6];
531 u_char addrhi[6];
532 int s = splimp();
533
534 switch (ifr->ifr_addr.sa_family) {
535
536 case AF_UNSPEC:
537 bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
538 bcopy(addrlo, addrhi, 6);
539 break;
540
541 #ifdef INET
542 case AF_INET:
543 sin = (struct sockaddr_in *)&(ifr->ifr_addr);
544 if (sin->sin_addr.s_addr == INADDR_ANY) {
545 /*
546 * An IP address of INADDR_ANY means listen to all
547 * of the Ethernet multicast addresses used for IP.
548 * (This is for the sake of IP multicast routers.)
549 */
550 bcopy(ether_ipmulticast_min, addrlo, 6);
551 bcopy(ether_ipmulticast_max, addrhi, 6);
552 }
553 else {
554 ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
555 bcopy(addrlo, addrhi, 6);
556 }
557 break;
558 #endif
559
560 default:
561 splx(s);
562 return (EAFNOSUPPORT);
563 }
564
565 /*
566 * Verify that we have valid Ethernet multicast addresses.
567 */
568 if ((addrlo[0] & 0x01) != 1 || (addrhi[0] & 0x01) != 1) {
569 splx(s);
570 return (EINVAL);
571 }
572 /*
573 * See if the address range is already in the list.
574 */
575 ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
576 if (enm != NULL) {
577 /*
578 * Found it; just increment the reference count.
579 */
580 ++enm->enm_refcount;
581 splx(s);
582 return (0);
583 }
584 /*
585 * New address or range; malloc a new multicast record
586 * and link it into the interface's multicast list.
587 */
588 enm = (struct ether_multi *)malloc(sizeof(*enm), M_IFMADDR, M_NOWAIT);
589 if (enm == NULL) {
590 splx(s);
591 return (ENOBUFS);
592 }
593 bcopy(addrlo, enm->enm_addrlo, 6);
594 bcopy(addrhi, enm->enm_addrhi, 6);
595 enm->enm_ac = ac;
596 enm->enm_refcount = 1;
597 LIST_INSERT_HEAD(&ac->ac_multiaddrs, enm, enm_list);
598 ac->ac_multicnt++;
599 splx(s);
600 /*
601 * Return ENETRESET to inform the driver that the list has changed
602 * and its reception filter should be adjusted accordingly.
603 */
604 return (ENETRESET);
605 }
606
607 /*
608 * Delete a multicast address record.
609 */
610 int
611 ether_delmulti(ifr, ac)
612 struct ifreq *ifr;
613 register struct arpcom *ac;
614 {
615 register struct ether_multi *enm;
616 register struct ether_multi **p;
617 struct sockaddr_in *sin;
618 u_char addrlo[6];
619 u_char addrhi[6];
620 int s = splimp();
621
622 switch (ifr->ifr_addr.sa_family) {
623
624 case AF_UNSPEC:
625 bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
626 bcopy(addrlo, addrhi, 6);
627 break;
628
629 #ifdef INET
630 case AF_INET:
631 sin = (struct sockaddr_in *)&(ifr->ifr_addr);
632 if (sin->sin_addr.s_addr == INADDR_ANY) {
633 /*
634 * An IP address of INADDR_ANY means stop listening
635 * to the range of Ethernet multicast addresses used
636 * for IP.
637 */
638 bcopy(ether_ipmulticast_min, addrlo, 6);
639 bcopy(ether_ipmulticast_max, addrhi, 6);
640 }
641 else {
642 ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
643 bcopy(addrlo, addrhi, 6);
644 }
645 break;
646 #endif
647
648 default:
649 splx(s);
650 return (EAFNOSUPPORT);
651 }
652
653 /*
654 * Look up the address in our list.
655 */
656 ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
657 if (enm == NULL) {
658 splx(s);
659 return (ENXIO);
660 }
661 if (--enm->enm_refcount != 0) {
662 /*
663 * Still some claims to this record.
664 */
665 splx(s);
666 return (0);
667 }
668 /*
669 * No remaining claims to this record; unlink and free it.
670 */
671 LIST_REMOVE(enm, enm_list);
672 free(enm, M_IFMADDR);
673 ac->ac_multicnt--;
674 splx(s);
675 /*
676 * Return ENETRESET to inform the driver that the list has changed
677 * and its reception filter should be adjusted accordingly.
678 */
679 return (ENETRESET);
680 }
681