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if_ethersubr.c revision 1.5
      1 /*
      2  * Copyright (c) 1982, 1989 Regents of the University of California.
      3  * 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  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  *
     33  *	from: @(#)if_ethersubr.c	7.13 (Berkeley) 4/20/91
     34  *	$Id: if_ethersubr.c,v 1.5 1994/01/23 23:41:14 deraadt Exp $
     35  */
     36 
     37 #include <sys/param.h>
     38 #include <sys/systm.h>
     39 #include <sys/kernel.h>
     40 #include <sys/malloc.h>
     41 #include <sys/mbuf.h>
     42 #include <sys/protosw.h>
     43 #include <sys/socket.h>
     44 #include <sys/ioctl.h>
     45 #include <sys/errno.h>
     46 #include <sys/syslog.h>
     47 
     48 #include <net/if.h>
     49 #include <net/netisr.h>
     50 #include <net/route.h>
     51 #include <net/if_llc.h>
     52 #include <net/if_dl.h>
     53 
     54 #ifdef INET
     55 #include <netinet/in.h>
     56 #include <netinet/in_var.h>
     57 #endif
     58 #include <netinet/if_ether.h>
     59 
     60 #ifdef NS
     61 #include <netns/ns.h>
     62 #include <netns/ns_if.h>
     63 #endif
     64 
     65 #ifdef ISO
     66 #include <netiso/argo_debug.h>
     67 #include <netiso/iso.h>
     68 #include <netiso/iso_var.h>
     69 #include <netiso/iso_snpac.h>
     70 #endif
     71 
     72 #include <machine/cpu.h>
     73 
     74 u_char	etherbroadcastaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
     75 extern	struct ifnet loif;
     76 
     77 /*
     78  * Ethernet output routine.
     79  * Encapsulate a packet of type family for the local net.
     80  * Use trailer local net encapsulation if enough data in first
     81  * packet leaves a multiple of 512 bytes of data in remainder.
     82  * Assumes that ifp is actually pointer to arpcom structure.
     83  */
     84 ether_output(ifp, m0, dst, rt)
     85 	register struct ifnet *ifp;
     86 	struct mbuf *m0;
     87 	struct sockaddr *dst;
     88 	struct rtentry *rt;
     89 {
     90 	u_short type;
     91 	int s, error = 0;
     92  	u_char edst[6];
     93 	struct in_addr idst;
     94 	register struct mbuf *m = m0;
     95 	struct mbuf *mcopy = (struct mbuf *)0;
     96 	register struct ether_header *eh;
     97 	int usetrailers, off, len = m->m_pkthdr.len;
     98 #define	ac ((struct arpcom *)ifp)
     99 
    100 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
    101 		error = ENETDOWN;
    102 		goto bad;
    103 	}
    104 	ifp->if_lastchange = time;
    105 	switch (dst->sa_family) {
    106 
    107 #ifdef INET
    108 	case AF_INET:
    109 		idst = ((struct sockaddr_in *)dst)->sin_addr;
    110  		if (!arpresolve(ac, m, &idst, edst, &usetrailers))
    111 			return (0);	/* if not yet resolved */
    112 		/* If broadcasting on a simplex interface, loopback a copy */
    113 		if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
    114 			mcopy = m_copy(m, 0, (int)M_COPYALL);
    115 		off = m->m_pkthdr.len - m->m_len;
    116 		if (usetrailers && off > 0 && (off & 0x1ff) == 0 &&
    117 		    (m->m_flags & M_EXT) == 0 &&
    118 		    m->m_data >= m->m_pktdat + 2 * sizeof (u_short)) {
    119 			type = ETHERTYPE_TRAIL + (off>>9);
    120 			m->m_data -= 2 * sizeof (u_short);
    121 			m->m_len += 2 * sizeof (u_short);
    122 			len += 2 * sizeof (u_short);
    123 			*mtod(m, u_short *) = htons((u_short)ETHERTYPE_IP);
    124 			*(mtod(m, u_short *) + 1) = htons((u_short)m->m_len);
    125 			goto gottrailertype;
    126 		}
    127 		type = ETHERTYPE_IP;
    128 		goto gottype;
    129 #endif
    130 #ifdef NS
    131 	case AF_NS:
    132 		type = ETHERTYPE_NS;
    133  		bcopy((caddr_t)&(((struct sockaddr_ns *)dst)->sns_addr.x_host),
    134 		    (caddr_t)edst, sizeof (edst));
    135 		if (!bcmp((caddr_t)edst, (caddr_t)&ns_thishost, sizeof(edst)))
    136 			return (looutput(ifp, m, dst, rt));
    137 		/* If broadcasting on a simplex interface, loopback a copy */
    138 		if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX))
    139 			mcopy = m_copy(m, 0, (int)M_COPYALL);
    140 		goto gottype;
    141 #endif
    142 #ifdef	ISO
    143 	case AF_ISO: {
    144 		int	snpalen;
    145 		struct	llc *l;
    146 
    147 	iso_again:
    148 		if (rt && rt->rt_gateway && (rt->rt_flags & RTF_UP)) {
    149 			if (rt->rt_flags & RTF_GATEWAY) {
    150 				if (rt->rt_llinfo) {
    151 					rt = (struct rtentry *)rt->rt_llinfo;
    152 					goto iso_again;
    153 				}
    154 			} else {
    155 				register struct sockaddr_dl *sdl =
    156 					(struct sockaddr_dl *)rt->rt_gateway;
    157 				if (sdl && sdl->sdl_family == AF_LINK
    158 				    && sdl->sdl_alen > 0) {
    159 					bcopy(LLADDR(sdl), (char *)edst,
    160 								sizeof(edst));
    161 					goto iso_resolved;
    162 				}
    163 			}
    164 		}
    165 		if ((error = iso_snparesolve(ifp, (struct sockaddr_iso *)dst,
    166 					(char *)edst, &snpalen)) > 0)
    167 			goto bad; /* Not Resolved */
    168 	iso_resolved:
    169 		/* If broadcasting on a simplex interface, loopback a copy */
    170 		if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX) &&
    171 		    (mcopy = m_copy(m, 0, (int)M_COPYALL))) {
    172 			M_PREPEND(mcopy, sizeof (*eh), M_DONTWAIT);
    173 			if (mcopy) {
    174 				eh = mtod(mcopy, struct ether_header *);
    175 				bcopy((caddr_t)edst,
    176 				      (caddr_t)eh->ether_dhost, sizeof (edst));
    177 				bcopy((caddr_t)ac->ac_enaddr,
    178 				      (caddr_t)eh->ether_shost, sizeof (edst));
    179 			}
    180 		}
    181 		M_PREPEND(m, 3, M_DONTWAIT);
    182 		if (m == NULL)
    183 			return (0);
    184 		type = m->m_pkthdr.len;
    185 		l = mtod(m, struct llc *);
    186 		l->llc_dsap = l->llc_ssap = LLC_ISO_LSAP;
    187 		l->llc_control = LLC_UI;
    188 		len += 3;
    189 		IFDEBUG(D_ETHER)
    190 			int i;
    191 			printf("unoutput: sending pkt to: ");
    192 			for (i=0; i<6; i++)
    193 				printf("%x ", edst[i] & 0xff);
    194 			printf("\n");
    195 		ENDDEBUG
    196 		}
    197 		goto gottype;
    198 #endif	ISO
    199 #ifdef RMP
    200 	case AF_RMP:
    201 		/*
    202 		 *  This is IEEE 802.3 -- the Ethernet `type' field is
    203 		 *  really a `length' field.
    204 		 */
    205 		type = m->m_len;
    206  		bcopy((caddr_t)dst->sa_data, (caddr_t)edst, sizeof(edst));
    207 		break;
    208 #endif
    209 
    210 	case AF_UNSPEC:
    211 		eh = (struct ether_header *)dst->sa_data;
    212  		bcopy((caddr_t)eh->ether_dhost, (caddr_t)edst, sizeof (edst));
    213 		/* AF_UNSPEC doesn't swap the byte order of the ether_type */
    214 		type = ntohs(eh->ether_type);
    215 		goto gottype;
    216 
    217 	default:
    218 		printf("%s%d: can't handle af%d\n", ifp->if_name, ifp->if_unit,
    219 			dst->sa_family);
    220 		error = EAFNOSUPPORT;
    221 		goto bad;
    222 	}
    223 
    224 gottrailertype:
    225 	/*
    226 	 * Packet to be sent as trailer: move first packet
    227 	 * (control information) to end of chain.
    228 	 */
    229 	while (m->m_next)
    230 		m = m->m_next;
    231 	m->m_next = m0;
    232 	m = m0->m_next;
    233 	m0->m_next = 0;
    234 
    235 gottype:
    236 	if (mcopy)
    237 		(void) looutput(ifp, mcopy, dst, rt);
    238 	/*
    239 	 * Add local net header.  If no space in first mbuf,
    240 	 * allocate another.
    241 	 */
    242 	M_PREPEND(m, sizeof (struct ether_header), M_DONTWAIT);
    243 	if (m == 0) {
    244 		error = ENOBUFS;
    245 		goto bad;
    246 	}
    247 	eh = mtod(m, struct ether_header *);
    248 	type = htons((u_short)type);
    249 	bcopy((caddr_t)&type,(caddr_t)&eh->ether_type,
    250 		sizeof(eh->ether_type));
    251  	bcopy((caddr_t)edst, (caddr_t)eh->ether_dhost, sizeof (edst));
    252  	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)eh->ether_shost,
    253 	    sizeof(eh->ether_shost));
    254 	s = splimp();
    255 	/*
    256 	 * Queue message on interface, and start output if interface
    257 	 * not yet active.
    258 	 */
    259 	if (IF_QFULL(&ifp->if_snd)) {
    260 		IF_DROP(&ifp->if_snd);
    261 		splx(s);
    262 		error = ENOBUFS;
    263 		goto bad;
    264 	}
    265 	IF_ENQUEUE(&ifp->if_snd, m);
    266 	if ((ifp->if_flags & IFF_OACTIVE) == 0)
    267 		(*ifp->if_start)(ifp);
    268 	splx(s);
    269 	ifp->if_obytes += len + sizeof (struct ether_header);
    270 #ifdef MULTICAST
    271 	if (m->m_flags & M_MCAST)
    272 #else
    273 	if (edst[0] & 1)
    274 #endif
    275 		ifp->if_omcasts++;
    276 	return (error);
    277 
    278 bad:
    279 	if (m)
    280 		m_freem(m);
    281 	return (error);
    282 }
    283 
    284 /*
    285  * Process a received Ethernet packet;
    286  * the packet is in the mbuf chain m without
    287  * the ether header, which is provided separately.
    288  */
    289 ether_input(ifp, eh, m)
    290 	struct ifnet *ifp;
    291 	register struct ether_header *eh;
    292 	struct mbuf *m;
    293 {
    294 	register struct ifqueue *inq;
    295 	register struct llc *l;
    296 	u_short etype;
    297 	int s;
    298 
    299 	ifp->if_lastchange = time;
    300 	ifp->if_ibytes += m->m_pkthdr.len + sizeof (*eh);
    301 #ifdef MULTICAST
    302  	if (eh->ether_dhost[0] & 1) {
    303  		if (bcmp((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
    304  			 sizeof(etherbroadcastaddr)) == 0)
    305  			m->m_flags |= M_BCAST;
    306  		else
    307  			m->m_flags |= M_MCAST;
    308  	}
    309 #else
    310 	if (bcmp((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
    311 	    sizeof(etherbroadcastaddr)) == 0)
    312 		m->m_flags |= M_BCAST;
    313 	else if (eh->ether_dhost[0] & 1)
    314 		m->m_flags |= M_MCAST;
    315 #endif
    316 	if (m->m_flags & (M_BCAST|M_MCAST))
    317 		ifp->if_imcasts++;
    318 
    319 	etype = ntohs(eh->ether_type);
    320 	switch (etype) {
    321 #ifdef INET
    322 	case ETHERTYPE_IP:
    323 		schednetisr(NETISR_IP);
    324 		inq = &ipintrq;
    325 		break;
    326 
    327 	case ETHERTYPE_ARP:
    328 		arpinput((struct arpcom *)ifp, m);
    329 		return;
    330 #endif
    331 #ifdef NS
    332 	case ETHERTYPE_NS:
    333 		schednetisr(NETISR_NS);
    334 		inq = &nsintrq;
    335 		break;
    336 
    337 #endif
    338 	default:
    339 #ifdef	ISO
    340 		if (etype > ETHERMTU)
    341 			goto dropanyway;
    342 		l = mtod(m, struct llc *);
    343 		switch (l->llc_control) {
    344 		case LLC_UI:
    345 		/* LLC_UI_P forbidden in class 1 service */
    346 		    if ((l->llc_dsap == LLC_ISO_LSAP) &&
    347 			(l->llc_ssap == LLC_ISO_LSAP)) {
    348 				/* LSAP for ISO */
    349 			if (m->m_pkthdr.len > etype)
    350 				m_adj(m, etype - m->m_pkthdr.len);
    351 			m->m_data += 3;		/* XXX */
    352 			m->m_len -= 3;		/* XXX */
    353 			m->m_pkthdr.len -= 3;	/* XXX */
    354 			M_PREPEND(m, sizeof *eh, M_DONTWAIT);
    355 			if (m == 0)
    356 				return;
    357 			*mtod(m, struct ether_header *) = *eh;
    358 			IFDEBUG(D_ETHER)
    359 			    printf("clnp packet");
    360 			ENDDEBUG
    361 			schednetisr(NETISR_ISO);
    362 			inq = &clnlintrq;
    363 			break;
    364 		    }
    365 		    goto dropanyway;
    366 
    367 		case LLC_XID:
    368 		case LLC_XID_P:
    369 		    if(m->m_len < 6)
    370 			goto dropanyway;
    371 		    l->llc_window = 0;
    372 		    l->llc_fid = 9;
    373 		    l->llc_class = 1;
    374 		    l->llc_dsap = l->llc_ssap = 0;
    375 		    /* Fall through to */
    376 		case LLC_TEST:
    377 		case LLC_TEST_P:
    378 		{
    379 		    struct sockaddr sa;
    380 		    register struct ether_header *eh2;
    381 		    int i;
    382 		    u_char c = l->llc_dsap;
    383 		    l->llc_dsap = l->llc_ssap;
    384 		    l->llc_ssap = c;
    385 		    if (m->m_flags & (M_BCAST | M_MCAST))
    386 			bcopy((caddr_t)ac->ac_enaddr,
    387 			      (caddr_t)eh->ether_dhost, 6);
    388 		    sa.sa_family = AF_UNSPEC;
    389 		    sa.sa_len = sizeof(sa);
    390 		    eh2 = (struct ether_header *)sa.sa_data;
    391 		    for (i = 0; i < 6; i++) {
    392 			eh2->ether_shost[i] = c = eh->ether_dhost[i];
    393 			eh2->ether_dhost[i] =
    394 				eh->ether_dhost[i] = eh->ether_shost[i];
    395 			eh->ether_shost[i] = c;
    396 		    }
    397 		    ifp->if_output(ifp, m, &sa);
    398 		    return;
    399 		}
    400 		dropanyway:
    401 		default:
    402 		    m_freem(m);
    403 		    return;
    404 	    }
    405 #else
    406 	    m_freem(m);
    407 	    return;
    408 #endif	ISO
    409 	}
    410 
    411 	s = splimp();
    412 	if (IF_QFULL(inq)) {
    413 		IF_DROP(inq);
    414 		m_freem(m);
    415 	} else
    416 		IF_ENQUEUE(inq, m);
    417 	splx(s);
    418 }
    419 
    420 /*
    421  * Convert Ethernet address to printable (loggable) representation.
    422  */
    423 static char digits[] = "0123456789abcdef";
    424 char *
    425 ether_sprintf(ap)
    426 	register u_char *ap;
    427 {
    428 	register i;
    429 	static char etherbuf[18];
    430 	register char *cp = etherbuf;
    431 
    432 	for (i = 0; i < 6; i++) {
    433 		*cp++ = digits[*ap >> 4];
    434 		*cp++ = digits[*ap++ & 0xf];
    435 		*cp++ = ':';
    436 	}
    437 	*--cp = 0;
    438 	return (etherbuf);
    439 }
    440 
    441 #ifdef MULTICAST
    442 u_char	ether_ipmulticast_min[6] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0x00 };
    443 u_char	ether_ipmulticast_max[6] = { 0x01, 0x00, 0x5e, 0x7f, 0xff, 0xff };
    444 
    445 /* XXX */
    446 #undef ac
    447 /*
    448  * Add an Ethernet multicast address or range of addresses to the list for a
    449  * given interface.
    450  */
    451 int
    452 ether_addmulti(ifr, ac)
    453 	struct ifreq *ifr;
    454 	register struct arpcom *ac;
    455 {
    456 	register struct ether_multi *enm;
    457 	struct sockaddr_in *sin;
    458 	u_char addrlo[6];
    459 	u_char addrhi[6];
    460 	int s = splimp();
    461 
    462 	switch (ifr->ifr_addr.sa_family) {
    463 
    464 	case AF_UNSPEC:
    465 		bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
    466 		bcopy(addrlo, addrhi, 6);
    467 		break;
    468 
    469 #ifdef INET
    470 	case AF_INET:
    471 		sin = (struct sockaddr_in *)&(ifr->ifr_addr);
    472 		if (sin->sin_addr.s_addr == INADDR_ANY) {
    473 			/*
    474 			 * An IP address of INADDR_ANY means listen to all
    475 			 * of the Ethernet multicast addresses used for IP.
    476 			 * (This is for the sake of IP multicast routers.)
    477 			 */
    478 			bcopy(ether_ipmulticast_min, addrlo, 6);
    479 			bcopy(ether_ipmulticast_max, addrhi, 6);
    480 		}
    481 		else {
    482 			ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
    483 			bcopy(addrlo, addrhi, 6);
    484 		}
    485 		break;
    486 #endif
    487 
    488 	default:
    489 		splx(s);
    490 		return (EAFNOSUPPORT);
    491 	}
    492 
    493 	/*
    494 	 * Verify that we have valid Ethernet multicast addresses.
    495 	 */
    496 	if ((addrlo[0] & 0x01) != 1 || (addrhi[0] & 0x01) != 1) {
    497 		splx(s);
    498 		return (EINVAL);
    499 	}
    500 	/*
    501 	 * See if the address range is already in the list.
    502 	 */
    503 	ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
    504 	if (enm != NULL) {
    505 		/*
    506 		 * Found it; just increment the reference count.
    507 		 */
    508 		++enm->enm_refcount;
    509 		splx(s);
    510 		return (0);
    511 	}
    512 	/*
    513 	 * New address or range; malloc a new multicast record
    514 	 * and link it into the interface's multicast list.
    515 	 */
    516 	enm = (struct ether_multi *)malloc(sizeof(*enm), M_IFMADDR, M_NOWAIT);
    517 	if (enm == NULL) {
    518 		splx(s);
    519 		return (ENOBUFS);
    520 	}
    521 	bcopy(addrlo, enm->enm_addrlo, 6);
    522 	bcopy(addrhi, enm->enm_addrhi, 6);
    523 	enm->enm_ac = ac;
    524 	enm->enm_refcount = 1;
    525 	enm->enm_next = ac->ac_multiaddrs;
    526 	ac->ac_multiaddrs = enm;
    527 	ac->ac_multicnt++;
    528 	splx(s);
    529 	/*
    530 	 * Return ENETRESET to inform the driver that the list has changed
    531 	 * and its reception filter should be adjusted accordingly.
    532 	 */
    533 	return (ENETRESET);
    534 }
    535 
    536 /*
    537  * Delete a multicast address record.
    538  */
    539 int
    540 ether_delmulti(ifr, ac)
    541 	struct ifreq *ifr;
    542 	register struct arpcom *ac;
    543 {
    544 	register struct ether_multi *enm;
    545 	register struct ether_multi **p;
    546 	struct sockaddr_in *sin;
    547 	u_char addrlo[6];
    548 	u_char addrhi[6];
    549 	int s = splimp();
    550 
    551 	switch (ifr->ifr_addr.sa_family) {
    552 
    553 	case AF_UNSPEC:
    554 		bcopy(ifr->ifr_addr.sa_data, addrlo, 6);
    555 		bcopy(addrlo, addrhi, 6);
    556 		break;
    557 
    558 #ifdef INET
    559 	case AF_INET:
    560 		sin = (struct sockaddr_in *)&(ifr->ifr_addr);
    561 		if (sin->sin_addr.s_addr == INADDR_ANY) {
    562 			/*
    563 			 * An IP address of INADDR_ANY means stop listening
    564 			 * to the range of Ethernet multicast addresses used
    565 			 * for IP.
    566 			 */
    567 			bcopy(ether_ipmulticast_min, addrlo, 6);
    568 			bcopy(ether_ipmulticast_max, addrhi, 6);
    569 		}
    570 		else {
    571 			ETHER_MAP_IP_MULTICAST(&sin->sin_addr, addrlo);
    572 			bcopy(addrlo, addrhi, 6);
    573 		}
    574 		break;
    575 #endif
    576 
    577 	default:
    578 		splx(s);
    579 		return (EAFNOSUPPORT);
    580 	}
    581 
    582 	/*
    583 	 * Look up the address in our list.
    584 	 */
    585 	ETHER_LOOKUP_MULTI(addrlo, addrhi, ac, enm);
    586 	if (enm == NULL) {
    587 		splx(s);
    588 		return (ENXIO);
    589 	}
    590 	if (--enm->enm_refcount != 0) {
    591 		/*
    592 		 * Still some claims to this record.
    593 		 */
    594 		splx(s);
    595 		return (0);
    596 	}
    597 	/*
    598 	 * No remaining claims to this record; unlink and free it.
    599 	 */
    600 	for (p = &enm->enm_ac->ac_multiaddrs;
    601 	     *p != enm;
    602 	     p = &(*p)->enm_next)
    603 		continue;
    604 	*p = (*p)->enm_next;
    605 	free(enm, M_IFMADDR);
    606 	ac->ac_multicnt--;
    607 	splx(s);
    608 	/*
    609 	 * Return ENETRESET to inform the driver that the list has changed
    610 	 * and its reception filter should be adjusted accordingly.
    611 	 */
    612 	return (ENETRESET);
    613 }
    614 #endif
    615