if_ethersubr.c revision 1.12 1 /* $NetBSD: if_ethersubr.c,v 1.12 1995/04/07 22:19:29 mycroft 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 #ifdef INET
59 #include <netinet/in.h>
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 int off, len = m->m_pkthdr.len;
110 struct arpcom *ac = (struct arpcom *)ifp;
111
112 if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
113 senderr(ENETDOWN);
114 ifp->if_lastchange = time;
115 if (rt = rt0) {
116 if ((rt->rt_flags & RTF_UP) == 0) {
117 if (rt0 = rt = rtalloc1(dst, 1))
118 rt->rt_refcnt--;
119 else
120 senderr(EHOSTUNREACH);
121 }
122 if (rt->rt_flags & RTF_GATEWAY) {
123 if (rt->rt_gwroute == 0)
124 goto lookup;
125 if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
126 rtfree(rt); rt = rt0;
127 lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
128 if ((rt = rt->rt_gwroute) == 0)
129 senderr(EHOSTUNREACH);
130 }
131 }
132 if (rt->rt_flags & RTF_REJECT)
133 if (rt->rt_rmx.rmx_expire == 0 ||
134 time.tv_sec < rt->rt_rmx.rmx_expire)
135 senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
136 }
137 switch (dst->sa_family) {
138
139 #ifdef INET
140 case AF_INET:
141 if (!arpresolve(ac, rt, m, dst, edst))
142 return (0); /* if not yet resolved */
143 /* If broadcasting on a simplex interface, loopback a copy */
144 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
145 mcopy = m_copy(m, 0, (int)M_COPYALL);
146 off = m->m_pkthdr.len - m->m_len;
147 etype = ETHERTYPE_IP;
148 break;
149 #endif
150 #ifdef NS
151 case AF_NS:
152 etype = ETHERTYPE_NS;
153 bcopy((caddr_t)&(((struct sockaddr_ns *)dst)->sns_addr.x_host),
154 (caddr_t)edst, sizeof (edst));
155 if (!bcmp((caddr_t)edst, (caddr_t)&ns_thishost, sizeof(edst)))
156 return (looutput(ifp, m, dst, rt));
157 /* If broadcasting on a simplex interface, loopback a copy */
158 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
159 mcopy = m_copy(m, 0, (int)M_COPYALL);
160 break;
161 #endif
162 #ifdef ISO
163 case AF_ISO: {
164 int snpalen;
165 struct llc *l;
166 register struct sockaddr_dl *sdl;
167
168 if (rt && (sdl = (struct sockaddr_dl *)rt->rt_gateway) &&
169 sdl->sdl_family == AF_LINK && sdl->sdl_alen > 0) {
170 bcopy(LLADDR(sdl), (caddr_t)edst, sizeof(edst));
171 } else if (error =
172 iso_snparesolve(ifp, (struct sockaddr_iso *)dst,
173 (char *)edst, &snpalen))
174 goto bad; /* Not Resolved */
175 /* If broadcasting on a simplex interface, loopback a copy */
176 if (*edst & 1)
177 m->m_flags |= (M_BCAST|M_MCAST);
178 if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX) &&
179 (mcopy = m_copy(m, 0, (int)M_COPYALL))) {
180 M_PREPEND(mcopy, sizeof (*eh), M_DONTWAIT);
181 if (mcopy) {
182 eh = mtod(mcopy, struct ether_header *);
183 bcopy((caddr_t)edst,
184 (caddr_t)eh->ether_dhost, sizeof (edst));
185 bcopy((caddr_t)ac->ac_enaddr,
186 (caddr_t)eh->ether_shost, sizeof (edst));
187 }
188 }
189 M_PREPEND(m, 3, M_DONTWAIT);
190 if (m == NULL)
191 return (0);
192 etype = m->m_pkthdr.len;
193 l = mtod(m, struct llc *);
194 l->llc_dsap = l->llc_ssap = LLC_ISO_LSAP;
195 l->llc_control = LLC_UI;
196 len += 3;
197 IFDEBUG(D_ETHER)
198 int i;
199 printf("unoutput: sending pkt to: ");
200 for (i=0; i<6; i++)
201 printf("%x ", edst[i] & 0xff);
202 printf("\n");
203 ENDDEBUG
204 } break;
205 #endif /* ISO */
206 #ifdef LLC
207 /* case AF_NSAP: */
208 case AF_CCITT: {
209 register struct sockaddr_dl *sdl =
210 (struct sockaddr_dl *) rt -> rt_gateway;
211
212 if (sdl && sdl->sdl_family == AF_LINK
213 && sdl->sdl_alen > 0) {
214 bcopy(LLADDR(sdl), (char *)edst,
215 sizeof(edst));
216 } else goto bad; /* Not a link interface ? Funny ... */
217 if ((ifp->if_flags & IFF_SIMPLEX) && (*edst & 1) &&
218 (mcopy = m_copy(m, 0, (int)M_COPYALL))) {
219 M_PREPEND(mcopy, sizeof (*eh), M_DONTWAIT);
220 if (mcopy) {
221 eh = mtod(mcopy, struct ether_header *);
222 bcopy((caddr_t)edst,
223 (caddr_t)eh->ether_dhost, sizeof (edst));
224 bcopy((caddr_t)ac->ac_enaddr,
225 (caddr_t)eh->ether_shost, sizeof (edst));
226 }
227 }
228 etype = m->m_pkthdr.len;
229 #ifdef LLC_DEBUG
230 {
231 int i;
232 register struct llc *l = mtod(m, struct llc *);
233
234 printf("ether_output: sending LLC2 pkt to: ");
235 for (i=0; i<6; i++)
236 printf("%x ", edst[i] & 0xff);
237 printf(" len 0x%x dsap 0x%x ssap 0x%x control 0x%x\n",
238 etype & 0xff, l->llc_dsap & 0xff, l->llc_ssap &0xff,
239 l->llc_control & 0xff);
240
241 }
242 #endif /* LLC_DEBUG */
243 } break;
244 #endif /* LLC */
245
246 case AF_UNSPEC:
247 eh = (struct ether_header *)dst->sa_data;
248 bcopy((caddr_t)eh->ether_dhost, (caddr_t)edst, sizeof (edst));
249 /* AF_UNSPEC doesn't swap the byte order of the ether_type. */
250 etype = ntohs(eh->ether_type);
251 break;
252
253 default:
254 printf("%s%d: can't handle af%d\n", ifp->if_name, ifp->if_unit,
255 dst->sa_family);
256 senderr(EAFNOSUPPORT);
257 }
258
259
260 if (mcopy)
261 (void) looutput(ifp, mcopy, dst, rt);
262 /*
263 * Add local net header. If no space in first mbuf,
264 * allocate another.
265 */
266 M_PREPEND(m, sizeof (struct ether_header), M_DONTWAIT);
267 if (m == 0)
268 senderr(ENOBUFS);
269 eh = mtod(m, struct ether_header *);
270 etype = htons(etype);
271 bcopy((caddr_t)&etype,(caddr_t)&eh->ether_type,
272 sizeof(eh->ether_type));
273 bcopy((caddr_t)edst, (caddr_t)eh->ether_dhost, sizeof (edst));
274 bcopy((caddr_t)ac->ac_enaddr, (caddr_t)eh->ether_shost,
275 sizeof(eh->ether_shost));
276 s = splimp();
277 /*
278 * Queue message on interface, and start output if interface
279 * not yet active.
280 */
281 if (IF_QFULL(&ifp->if_snd)) {
282 IF_DROP(&ifp->if_snd);
283 splx(s);
284 senderr(ENOBUFS);
285 }
286 IF_ENQUEUE(&ifp->if_snd, m);
287 if ((ifp->if_flags & IFF_OACTIVE) == 0)
288 (*ifp->if_start)(ifp);
289 splx(s);
290 ifp->if_obytes += len + sizeof (struct ether_header);
291 if (m->m_flags & M_MCAST)
292 ifp->if_omcasts++;
293 return (error);
294
295 bad:
296 if (m)
297 m_freem(m);
298 return (error);
299 }
300
301 /*
302 * Process a received Ethernet packet;
303 * the packet is in the mbuf chain m without
304 * the ether header, which is provided separately.
305 */
306 void
307 ether_input(ifp, eh, m)
308 struct ifnet *ifp;
309 register struct ether_header *eh;
310 struct mbuf *m;
311 {
312 register struct ifqueue *inq;
313 register struct llc *l;
314 u_int16_t etype;
315 struct arpcom *ac = (struct arpcom *)ifp;
316 int s;
317
318 if ((ifp->if_flags & IFF_UP) == 0) {
319 m_freem(m);
320 return;
321 }
322 ifp->if_lastchange = time;
323 ifp->if_ibytes += m->m_pkthdr.len + sizeof (*eh);
324 if (eh->ether_dhost[0] & 1) {
325 if (bcmp((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
326 sizeof(etherbroadcastaddr)) == 0)
327 m->m_flags |= M_BCAST;
328 else
329 m->m_flags |= M_MCAST;
330 }
331 if (m->m_flags & (M_BCAST|M_MCAST))
332 ifp->if_imcasts++;
333
334 etype = ntohs(eh->ether_type);
335 switch (etype) {
336 #ifdef INET
337 case ETHERTYPE_IP:
338 schednetisr(NETISR_IP);
339 inq = &ipintrq;
340 break;
341
342 case ETHERTYPE_ARP:
343 schednetisr(NETISR_ARP);
344 inq = &arpintrq;
345 break;
346
347 case ETHERTYPE_REVARP:
348 revarpinput(m); /* XXX queue? */
349 return;
350 #endif
351 #ifdef NS
352 case ETHERTYPE_NS:
353 schednetisr(NETISR_NS);
354 inq = &nsintrq;
355 break;
356
357 #endif
358 default:
359 #if defined (ISO) || defined (LLC)
360 if (etype > ETHERMTU)
361 goto dropanyway;
362 l = mtod(m, struct llc *);
363 switch (l->llc_dsap) {
364 #ifdef ISO
365 case LLC_ISO_LSAP:
366 switch (l->llc_control) {
367 case LLC_UI:
368 /* LLC_UI_P forbidden in class 1 service */
369 if ((l->llc_dsap == LLC_ISO_LSAP) &&
370 (l->llc_ssap == LLC_ISO_LSAP)) {
371 /* LSAP for ISO */
372 if (m->m_pkthdr.len > etype)
373 m_adj(m, etype - m->m_pkthdr.len);
374 m->m_data += 3; /* XXX */
375 m->m_len -= 3; /* XXX */
376 m->m_pkthdr.len -= 3; /* XXX */
377 M_PREPEND(m, sizeof *eh, M_DONTWAIT);
378 if (m == 0)
379 return;
380 *mtod(m, struct ether_header *) = *eh;
381 IFDEBUG(D_ETHER)
382 printf("clnp packet");
383 ENDDEBUG
384 schednetisr(NETISR_ISO);
385 inq = &clnlintrq;
386 break;
387 }
388 goto dropanyway;
389
390 case LLC_XID:
391 case LLC_XID_P:
392 if(m->m_len < 6)
393 goto dropanyway;
394 l->llc_window = 0;
395 l->llc_fid = 9;
396 l->llc_class = 1;
397 l->llc_dsap = l->llc_ssap = 0;
398 /* Fall through to */
399 case LLC_TEST:
400 case LLC_TEST_P:
401 {
402 struct sockaddr sa;
403 register struct ether_header *eh2;
404 int i;
405 u_char c = l->llc_dsap;
406
407 l->llc_dsap = l->llc_ssap;
408 l->llc_ssap = c;
409 if (m->m_flags & (M_BCAST | M_MCAST))
410 bcopy((caddr_t)ac->ac_enaddr,
411 (caddr_t)eh->ether_dhost, 6);
412 sa.sa_family = AF_UNSPEC;
413 sa.sa_len = sizeof(sa);
414 eh2 = (struct ether_header *)sa.sa_data;
415 for (i = 0; i < 6; i++) {
416 eh2->ether_shost[i] = c = eh->ether_dhost[i];
417 eh2->ether_dhost[i] =
418 eh->ether_dhost[i] = eh->ether_shost[i];
419 eh->ether_shost[i] = c;
420 }
421 ifp->if_output(ifp, m, &sa, NULL);
422 return;
423 }
424 default:
425 m_freem(m);
426 return;
427 }
428 break;
429 #endif /* ISO */
430 #ifdef LLC
431 case LLC_X25_LSAP:
432 {
433 if (m->m_pkthdr.len > etype)
434 m_adj(m, etype - m->m_pkthdr.len);
435 M_PREPEND(m, sizeof(struct sdl_hdr) , M_DONTWAIT);
436 if (m == 0)
437 return;
438 if ( !sdl_sethdrif(ifp, eh->ether_shost, LLC_X25_LSAP,
439 eh->ether_dhost, LLC_X25_LSAP, 6,
440 mtod(m, struct sdl_hdr *)))
441 panic("ETHER cons addr failure");
442 mtod(m, struct sdl_hdr *)->sdlhdr_len = etype;
443 #ifdef LLC_DEBUG
444 printf("llc packet\n");
445 #endif /* LLC_DEBUG */
446 schednetisr(NETISR_CCITT);
447 inq = &llcintrq;
448 break;
449 }
450 #endif /* LLC */
451 dropanyway:
452 default:
453 m_freem(m);
454 return;
455 }
456 #else /* ISO || LLC */
457 m_freem(m);
458 return;
459 #endif /* ISO || LLC */
460 }
461
462 s = splimp();
463 if (IF_QFULL(inq)) {
464 IF_DROP(inq);
465 m_freem(m);
466 } else
467 IF_ENQUEUE(inq, m);
468 splx(s);
469 }
470
471 /*
472 * Convert Ethernet address to printable (loggable) representation.
473 */
474 static char digits[] = "0123456789abcdef";
475 char *
476 ether_sprintf(ap)
477 register u_char *ap;
478 {
479 register i;
480 static char etherbuf[18];
481 register char *cp = etherbuf;
482
483 for (i = 0; i < 6; i++) {
484 *cp++ = digits[*ap >> 4];
485 *cp++ = digits[*ap++ & 0xf];
486 *cp++ = ':';
487 }
488 *--cp = 0;
489 return (etherbuf);
490 }
491
492 /*
493 * Perform common duties while attaching to interface list
494 */
495 void
496 ether_ifattach(ifp)
497 register struct ifnet *ifp;
498 {
499 register struct ifaddr *ifa;
500 register struct sockaddr_dl *sdl;
501
502 ifp->if_type = IFT_ETHER;
503 ifp->if_addrlen = 6;
504 ifp->if_hdrlen = 14;
505 ifp->if_mtu = ETHERMTU;
506 ifp->if_output = ether_output;
507 for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
508 if ((sdl = (struct sockaddr_dl *)ifa->ifa_addr) &&
509 sdl->sdl_family == AF_LINK) {
510 sdl->sdl_type = IFT_ETHER;
511 sdl->sdl_alen = ifp->if_addrlen;
512 bcopy((caddr_t)((struct arpcom *)ifp)->ac_enaddr,
513 LLADDR(sdl), ifp->if_addrlen);
514 break;
515 }
516 }
517
518 u_char ether_ipmulticast_min[6] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0x00 };
519 u_char ether_ipmulticast_max[6] = { 0x01, 0x00, 0x5e, 0x7f, 0xff, 0xff };
520 /*
521 * Add an Ethernet multicast address or range of addresses to the list for a
522 * given interface.
523 */
524 int
525 ether_addmulti(ifr, ac)
526 struct ifreq *ifr;
527 register struct arpcom *ac;
528 {
529 register struct ether_multi *enm;
530 struct sockaddr_in *sin;
531 u_char addrlo[6];
532 u_char addrhi[6];
533 int s = splimp();
534
535 switch (ifr->ifr_addr.sa_family) {
536
537 case AF_UNSPEC:
538 bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
539 bcopy(addrlo, addrhi, 6);
540 break;
541
542 #ifdef INET
543 case AF_INET:
544 sin = (struct sockaddr_in *)&(ifr->ifr_addr);
545 if (sin->sin_addr.s_addr == INADDR_ANY) {
546 /*
547 * An IP address of INADDR_ANY means listen to all
548 * of the Ethernet multicast addresses used for IP.
549 * (This is for the sake of IP multicast routers.)
550 */
551 bcopy(ether_ipmulticast_min, addrlo, 6);
552 bcopy(ether_ipmulticast_max, addrhi, 6);
553 }
554 else {
555 ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
556 bcopy(addrlo, addrhi, 6);
557 }
558 break;
559 #endif
560
561 default:
562 splx(s);
563 return (EAFNOSUPPORT);
564 }
565
566 /*
567 * Verify that we have valid Ethernet multicast addresses.
568 */
569 if ((addrlo[0] & 0x01) != 1 || (addrhi[0] & 0x01) != 1) {
570 splx(s);
571 return (EINVAL);
572 }
573 /*
574 * See if the address range is already in the list.
575 */
576 ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
577 if (enm != NULL) {
578 /*
579 * Found it; just increment the reference count.
580 */
581 ++enm->enm_refcount;
582 splx(s);
583 return (0);
584 }
585 /*
586 * New address or range; malloc a new multicast record
587 * and link it into the interface's multicast list.
588 */
589 enm = (struct ether_multi *)malloc(sizeof(*enm), M_IFMADDR, M_NOWAIT);
590 if (enm == NULL) {
591 splx(s);
592 return (ENOBUFS);
593 }
594 bcopy(addrlo, enm->enm_addrlo, 6);
595 bcopy(addrhi, enm->enm_addrhi, 6);
596 enm->enm_ac = ac;
597 enm->enm_refcount = 1;
598 enm->enm_next = ac->ac_multiaddrs;
599 ac->ac_multiaddrs = enm;
600 ac->ac_multicnt++;
601 splx(s);
602 /*
603 * Return ENETRESET to inform the driver that the list has changed
604 * and its reception filter should be adjusted accordingly.
605 */
606 return (ENETRESET);
607 }
608
609 /*
610 * Delete a multicast address record.
611 */
612 int
613 ether_delmulti(ifr, ac)
614 struct ifreq *ifr;
615 register struct arpcom *ac;
616 {
617 register struct ether_multi *enm;
618 register struct ether_multi **p;
619 struct sockaddr_in *sin;
620 u_char addrlo[6];
621 u_char addrhi[6];
622 int s = splimp();
623
624 switch (ifr->ifr_addr.sa_family) {
625
626 case AF_UNSPEC:
627 bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
628 bcopy(addrlo, addrhi, 6);
629 break;
630
631 #ifdef INET
632 case AF_INET:
633 sin = (struct sockaddr_in *)&(ifr->ifr_addr);
634 if (sin->sin_addr.s_addr == INADDR_ANY) {
635 /*
636 * An IP address of INADDR_ANY means stop listening
637 * to the range of Ethernet multicast addresses used
638 * for IP.
639 */
640 bcopy(ether_ipmulticast_min, addrlo, 6);
641 bcopy(ether_ipmulticast_max, addrhi, 6);
642 }
643 else {
644 ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
645 bcopy(addrlo, addrhi, 6);
646 }
647 break;
648 #endif
649
650 default:
651 splx(s);
652 return (EAFNOSUPPORT);
653 }
654
655 /*
656 * Look up the address in our list.
657 */
658 ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
659 if (enm == NULL) {
660 splx(s);
661 return (ENXIO);
662 }
663 if (--enm->enm_refcount != 0) {
664 /*
665 * Still some claims to this record.
666 */
667 splx(s);
668 return (0);
669 }
670 /*
671 * No remaining claims to this record; unlink and free it.
672 */
673 for (p = &enm->enm_ac->ac_multiaddrs;
674 *p != enm;
675 p = &(*p)->enm_next)
676 continue;
677 *p = (*p)->enm_next;
678 free(enm, M_IFMADDR);
679 ac->ac_multicnt--;
680 splx(s);
681 /*
682 * Return ENETRESET to inform the driver that the list has changed
683 * and its reception filter should be adjusted accordingly.
684 */
685 return (ENETRESET);
686 }
687