xref: /freebsd/sys/netinet6/mld6.c (revision 6607310b740c499e273ae5bbf1f308ed91b61c05)
1 /*	$FreeBSD$	*/
2 /*	$KAME: mld6.c,v 1.27 2001/04/04 05:17:30 itojun Exp $	*/
3 
4 /*-
5  * Copyright (C) 1998 WIDE Project.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 /*-
34  * Copyright (c) 1988 Stephen Deering.
35  * Copyright (c) 1992, 1993
36  *	The Regents of the University of California.  All rights reserved.
37  *
38  * This code is derived from software contributed to Berkeley by
39  * Stephen Deering of Stanford University.
40  *
41  * Redistribution and use in source and binary forms, with or without
42  * modification, are permitted provided that the following conditions
43  * are met:
44  * 1. Redistributions of source code must retain the above copyright
45  *    notice, this list of conditions and the following disclaimer.
46  * 2. Redistributions in binary form must reproduce the above copyright
47  *    notice, this list of conditions and the following disclaimer in the
48  *    documentation and/or other materials provided with the distribution.
49  * 4. Neither the name of the University nor the names of its contributors
50  *    may be used to endorse or promote products derived from this software
51  *    without specific prior written permission.
52  *
53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63  * SUCH DAMAGE.
64  *
65  *	@(#)igmp.c	8.1 (Berkeley) 7/19/93
66  */
67 
68 #include "opt_inet.h"
69 #include "opt_inet6.h"
70 
71 #include <sys/param.h>
72 #include <sys/systm.h>
73 #include <sys/mbuf.h>
74 #include <sys/socket.h>
75 #include <sys/protosw.h>
76 #include <sys/syslog.h>
77 #include <sys/kernel.h>
78 #include <sys/callout.h>
79 #include <sys/malloc.h>
80 
81 #include <net/if.h>
82 
83 #include <netinet/in.h>
84 #include <netinet/in_var.h>
85 #include <netinet6/in6_var.h>
86 #include <netinet/ip6.h>
87 #include <netinet6/ip6_var.h>
88 #include <netinet6/scope6_var.h>
89 #include <netinet/icmp6.h>
90 #include <netinet6/mld6_var.h>
91 
92 /*
93  * Protocol constants
94  */
95 
96 /* denotes that the MLD max response delay field specifies time in milliseconds */
97 #define MLD_TIMER_SCALE	1000
98 /*
99  * time between repetitions of a node's initial report of interest in a
100  * multicast address(in seconds)
101  */
102 #define MLD_UNSOLICITED_REPORT_INTERVAL	10
103 
104 static struct ip6_pktopts ip6_opts;
105 
106 static void mld6_sendpkt(struct in6_multi *, int, const struct in6_addr *);
107 static void mld_starttimer(struct in6_multi *);
108 static void mld_stoptimer(struct in6_multi *);
109 static void mld_timeo(struct in6_multi *);
110 static u_long mld_timerresid(struct in6_multi *);
111 
112 void
113 mld6_init(void)
114 {
115 	static u_int8_t hbh_buf[8];
116 	struct ip6_hbh *hbh = (struct ip6_hbh *)hbh_buf;
117 	u_int16_t rtalert_code = htons((u_int16_t)IP6OPT_RTALERT_MLD);
118 
119 	/* ip6h_nxt will be fill in later */
120 	hbh->ip6h_len = 0;	/* (8 >> 3) - 1 */
121 
122 	/* XXX: grotty hard coding... */
123 	hbh_buf[2] = IP6OPT_PADN;	/* 2 byte padding */
124 	hbh_buf[3] = 0;
125 	hbh_buf[4] = IP6OPT_ROUTER_ALERT;
126 	hbh_buf[5] = IP6OPT_RTALERT_LEN - 2;
127 	bcopy((caddr_t)&rtalert_code, &hbh_buf[6], sizeof(u_int16_t));
128 
129 	ip6_initpktopts(&ip6_opts);
130 	ip6_opts.ip6po_hbh = hbh;
131 }
132 
133 static void
134 mld_starttimer(struct in6_multi *in6m)
135 {
136 	struct timeval now;
137 
138 	microtime(&now);
139 	in6m->in6m_timer_expire.tv_sec = now.tv_sec + in6m->in6m_timer / hz;
140 	in6m->in6m_timer_expire.tv_usec = now.tv_usec +
141 	    (in6m->in6m_timer % hz) * (1000000 / hz);
142 	if (in6m->in6m_timer_expire.tv_usec > 1000000) {
143 		in6m->in6m_timer_expire.tv_sec++;
144 		in6m->in6m_timer_expire.tv_usec -= 1000000;
145 	}
146 
147 	/* start or restart the timer */
148 	callout_reset(in6m->in6m_timer_ch, in6m->in6m_timer,
149 	    (void (*) __P((void *)))mld_timeo, in6m);
150 }
151 
152 static void
153 mld_stoptimer(struct in6_multi *in6m)
154 {
155 	if (in6m->in6m_timer == IN6M_TIMER_UNDEF)
156 		return;
157 
158 	callout_stop(in6m->in6m_timer_ch);
159 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
160 }
161 
162 static void
163 mld_timeo(struct in6_multi *in6m)
164 {
165 	int s = splnet();
166 
167 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
168 
169 	callout_stop(in6m->in6m_timer_ch);
170 
171 	switch (in6m->in6m_state) {
172 	case MLD_REPORTPENDING:
173 		mld6_start_listening(in6m);
174 		break;
175 	default:
176 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
177 		break;
178 	}
179 
180 	splx(s);
181 }
182 
183 static u_long
184 mld_timerresid(struct in6_multi *in6m)
185 {
186 	struct timeval now, diff;
187 
188 	microtime(&now);
189 
190 	if (now.tv_sec > in6m->in6m_timer_expire.tv_sec ||
191 	    (now.tv_sec == in6m->in6m_timer_expire.tv_sec &&
192 	    now.tv_usec > in6m->in6m_timer_expire.tv_usec)) {
193 		return (0);
194 	}
195 	diff = in6m->in6m_timer_expire;
196 	diff.tv_sec -= now.tv_sec;
197 	diff.tv_usec -= now.tv_usec;
198 	if (diff.tv_usec < 0) {
199 		diff.tv_sec--;
200 		diff.tv_usec += 1000000;
201 	}
202 
203 	/* return the remaining time in milliseconds */
204 	return (((u_long)(diff.tv_sec * 1000000 + diff.tv_usec)) / 1000);
205 }
206 
207 void
208 mld6_start_listening(struct in6_multi *in6m)
209 {
210 	struct in6_addr all_in6;
211 	int s = splnet();
212 
213 	/*
214 	 * RFC2710 page 10:
215 	 * The node never sends a Report or Done for the link-scope all-nodes
216 	 * address.
217 	 * MLD messages are never sent for multicast addresses whose scope is 0
218 	 * (reserved) or 1 (node-local).
219 	 */
220 	all_in6 = in6addr_linklocal_allnodes;
221 	if (in6_setscope(&all_in6, in6m->in6m_ifp, NULL)) {
222 		/* XXX: this should not happen! */
223 		in6m->in6m_timer = 0;
224 		in6m->in6m_state = MLD_OTHERLISTENER;
225 	}
226 	if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
227 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
228 	    IPV6_ADDR_SCOPE_LINKLOCAL) {
229 		in6m->in6m_timer = 0;
230 		in6m->in6m_state = MLD_OTHERLISTENER;
231 	} else {
232 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
233 		in6m->in6m_timer = arc4random() %
234 			MLD_UNSOLICITED_REPORT_INTERVAL * hz;
235 		in6m->in6m_state = MLD_IREPORTEDLAST;
236 
237 		mld_starttimer(in6m);
238 	}
239 	splx(s);
240 }
241 
242 void
243 mld6_stop_listening(struct in6_multi *in6m)
244 {
245 	struct in6_addr allnode, allrouter;
246 
247 	allnode = in6addr_linklocal_allnodes;
248 	if (in6_setscope(&allnode, in6m->in6m_ifp, NULL)) {
249 		/* XXX: this should not happen! */
250 		return;
251 	}
252 	allrouter = in6addr_linklocal_allrouters;
253 	if (in6_setscope(&allrouter, in6m->in6m_ifp, NULL)) {
254 		/* XXX impossible */
255 		return;
256 	}
257 	if (in6m->in6m_state == MLD_IREPORTEDLAST &&
258 	    !IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &allnode) &&
259 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) >
260 	    IPV6_ADDR_SCOPE_INTFACELOCAL) {
261 		mld6_sendpkt(in6m, MLD_LISTENER_DONE, &allrouter);
262 	}
263 }
264 
265 void
266 mld6_input(struct mbuf *m, int off)
267 {
268 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
269 	struct mld_hdr *mldh;
270 	struct ifnet *ifp = m->m_pkthdr.rcvif;
271 	struct in6_multi *in6m;
272 	struct in6_addr mld_addr, all_in6;
273 	struct in6_ifaddr *ia;
274 	struct ifmultiaddr *ifma;
275 	int timer;		/* timer value in the MLD query header */
276 
277 #ifndef PULLDOWN_TEST
278 	IP6_EXTHDR_CHECK(m, off, sizeof(*mldh),);
279 	mldh = (struct mld_hdr *)(mtod(m, caddr_t) + off);
280 #else
281 	IP6_EXTHDR_GET(mldh, struct mld_hdr *, m, off, sizeof(*mldh));
282 	if (mldh == NULL) {
283 		icmp6stat.icp6s_tooshort++;
284 		return;
285 	}
286 #endif
287 
288 	/* source address validation */
289 	ip6 = mtod(m, struct ip6_hdr *); /* in case mpullup */
290 	if (!IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src)) {
291 		char ip6bufs[INET6_ADDRSTRLEN], ip6bufg[INET6_ADDRSTRLEN];
292 		log(LOG_ERR,
293 		    "mld6_input: src %s is not link-local (grp=%s)\n",
294 		    ip6_sprintf(ip6bufs, &ip6->ip6_src),
295 		    ip6_sprintf(ip6bufg, &mldh->mld_addr));
296 		/*
297 		 * spec (RFC2710) does not explicitly
298 		 * specify to discard the packet from a non link-local
299 		 * source address. But we believe it's expected to do so.
300 		 * XXX: do we have to allow :: as source?
301 		 */
302 		m_freem(m);
303 		return;
304 	}
305 
306 	/*
307 	 * make a copy for local work (in6_setscope() may modify the 1st arg)
308 	 */
309 	mld_addr = mldh->mld_addr;
310 	if (in6_setscope(&mld_addr, ifp, NULL)) {
311 		/* XXX: this should not happen! */
312 		m_free(m);
313 		return;
314 	}
315 
316 	/*
317 	 * In the MLD6 specification, there are 3 states and a flag.
318 	 *
319 	 * In Non-Listener state, we simply don't have a membership record.
320 	 * In Delaying Listener state, our timer is running (in6m->in6m_timer)
321 	 * In Idle Listener state, our timer is not running
322 	 * (in6m->in6m_timer==IN6M_TIMER_UNDEF)
323 	 *
324 	 * The flag is in6m->in6m_state, it is set to MLD_OTHERLISTENER if
325 	 * we have heard a report from another member, or MLD_IREPORTEDLAST
326 	 * if we sent the last report.
327 	 */
328 	switch(mldh->mld_type) {
329 	case MLD_LISTENER_QUERY:
330 		if (ifp->if_flags & IFF_LOOPBACK)
331 			break;
332 
333 		if (!IN6_IS_ADDR_UNSPECIFIED(&mld_addr) &&
334 		    !IN6_IS_ADDR_MULTICAST(&mld_addr))
335 			break;	/* print error or log stat? */
336 
337 		all_in6 = in6addr_linklocal_allnodes;
338 		if (in6_setscope(&all_in6, ifp, NULL)) {
339 			/* XXX: this should not happen! */
340 			break;
341 		}
342 
343 		/*
344 		 * - Start the timers in all of our membership records
345 		 *   that the query applies to for the interface on
346 		 *   which the query arrived excl. those that belong
347 		 *   to the "all-nodes" group (ff02::1).
348 		 * - Restart any timer that is already running but has
349 		 *   A value longer than the requested timeout.
350 		 * - Use the value specified in the query message as
351 		 *   the maximum timeout.
352 		 */
353 		timer = ntohs(mldh->mld_maxdelay);
354 
355 		IFP_TO_IA6(ifp, ia);
356 		if (ia == NULL)
357 			break;
358 
359 		/*
360 		 * XXX: System timer resolution is too low to handle Max
361 		 * Response Delay, so set 1 to the internal timer even if
362 		 * the calculated value equals to zero when Max Response
363 		 * Delay is positive.
364 		 */
365 		timer = ntohs(mldh->mld_maxdelay) * PR_FASTHZ / MLD_TIMER_SCALE;
366 		if (timer == 0 && mldh->mld_maxdelay)
367 			timer = 1;
368 
369 		IF_ADDR_LOCK(ifp);
370 		TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
371 			if (ifma->ifma_addr->sa_family != AF_INET6)
372 				continue;
373 			in6m = (struct in6_multi *)ifma->ifma_protospec;
374 
375 			if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
376 			    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
377 			    IPV6_ADDR_SCOPE_LINKLOCAL)
378 				continue;
379 
380 			if (IN6_IS_ADDR_UNSPECIFIED(&mld_addr) ||
381 			    IN6_ARE_ADDR_EQUAL(&mld_addr, &in6m->in6m_addr)) {
382 				if (timer == 0) {
383 					/* send a report immediately */
384 					mld_stoptimer(in6m);
385 					mld6_sendpkt(in6m, MLD_LISTENER_REPORT,
386 						NULL);
387 					in6m->in6m_timer = 0; /* reset timer */
388 					in6m->in6m_state = MLD_IREPORTEDLAST;
389 				}
390 				else if (in6m->in6m_timer == IN6M_TIMER_UNDEF ||
391 				    mld_timerresid(in6m) > (u_long)timer) {
392 					in6m->in6m_timer = arc4random() %
393 					    (int)((long)(timer * hz) / 1000);
394 					mld_starttimer(in6m);
395 				}
396 			}
397 		}
398 		IF_ADDR_UNLOCK(ifp);
399 		break;
400 
401 	case MLD_LISTENER_REPORT:
402 		/*
403 		 * For fast leave to work, we have to know that we are the
404 		 * last person to send a report for this group.  Reports
405 		 * can potentially get looped back if we are a multicast
406 		 * router, so discard reports sourced by me.
407 		 * Note that it is impossible to check IFF_LOOPBACK flag of
408 		 * ifp for this purpose, since ip6_mloopback pass the physical
409 		 * interface to looutput.
410 		 */
411 		if (m->m_flags & M_LOOP) /* XXX: grotty flag, but efficient */
412 			break;
413 
414 		if (!IN6_IS_ADDR_MULTICAST(&mld_addr))
415 			break;
416 
417 		/*
418 		 * If we belong to the group being reported, stop
419 		 * our timer for that group.
420 		 */
421 		IN6_LOOKUP_MULTI(mld_addr, ifp, in6m);
422 		if (in6m) {
423 			in6m->in6m_timer = 0; /* transit to idle state */
424 			in6m->in6m_state = MLD_OTHERLISTENER; /* clear flag */
425 		}
426 		break;
427 	default:		/* this is impossible */
428 		log(LOG_ERR, "mld6_input: illegal type(%d)", mldh->mld_type);
429 		break;
430 	}
431 
432 	m_freem(m);
433 }
434 
435 static void
436 mld6_sendpkt(struct in6_multi *in6m, int type, const struct in6_addr *dst)
437 {
438 	struct mbuf *mh, *md;
439 	struct mld_hdr *mldh;
440 	struct ip6_hdr *ip6;
441 	struct ip6_moptions im6o;
442 	struct in6_ifaddr *ia;
443 	struct ifnet *ifp = in6m->in6m_ifp;
444 	struct ifnet *outif = NULL;
445 
446 	/*
447 	 * At first, find a link local address on the outgoing interface
448 	 * to use as the source address of the MLD packet.
449 	 */
450 	if ((ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST))
451 	    == NULL)
452 		return;
453 
454 	/*
455 	 * Allocate mbufs to store ip6 header and MLD header.
456 	 * We allocate 2 mbufs and make chain in advance because
457 	 * it is more convenient when inserting the hop-by-hop option later.
458 	 */
459 	MGETHDR(mh, M_DONTWAIT, MT_HEADER);
460 	if (mh == NULL)
461 		return;
462 	MGET(md, M_DONTWAIT, MT_DATA);
463 	if (md == NULL) {
464 		m_free(mh);
465 		return;
466 	}
467 	mh->m_next = md;
468 
469 	mh->m_pkthdr.rcvif = NULL;
470 	mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
471 	mh->m_len = sizeof(struct ip6_hdr);
472 	MH_ALIGN(mh, sizeof(struct ip6_hdr));
473 
474 	/* fill in the ip6 header */
475 	ip6 = mtod(mh, struct ip6_hdr *);
476 	ip6->ip6_flow = 0;
477 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
478 	ip6->ip6_vfc |= IPV6_VERSION;
479 	/* ip6_plen will be set later */
480 	ip6->ip6_nxt = IPPROTO_ICMPV6;
481 	/* ip6_hlim will be set by im6o.im6o_multicast_hlim */
482 	ip6->ip6_src = ia->ia_addr.sin6_addr;
483 	ip6->ip6_dst = dst ? *dst : in6m->in6m_addr;
484 
485 	/* fill in the MLD header */
486 	md->m_len = sizeof(struct mld_hdr);
487 	mldh = mtod(md, struct mld_hdr *);
488 	mldh->mld_type = type;
489 	mldh->mld_code = 0;
490 	mldh->mld_cksum = 0;
491 	/* XXX: we assume the function will not be called for query messages */
492 	mldh->mld_maxdelay = 0;
493 	mldh->mld_reserved = 0;
494 	mldh->mld_addr = in6m->in6m_addr;
495 	in6_clearscope(&mldh->mld_addr); /* XXX */
496 	mldh->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6, sizeof(struct ip6_hdr),
497 				    sizeof(struct mld_hdr));
498 
499 	/* construct multicast option */
500 	bzero(&im6o, sizeof(im6o));
501 	im6o.im6o_multicast_ifp = ifp;
502 	im6o.im6o_multicast_hlim = 1;
503 
504 	/*
505 	 * Request loopback of the report if we are acting as a multicast
506 	 * router, so that the process-level routing daemon can hear it.
507 	 */
508 	im6o.im6o_multicast_loop = (ip6_mrouter != NULL);
509 
510 	/* increment output statictics */
511 	icmp6stat.icp6s_outhist[type]++;
512 
513 	ip6_output(mh, &ip6_opts, NULL, 0, &im6o, &outif, NULL);
514 	if (outif) {
515 		icmp6_ifstat_inc(outif, ifs6_out_msg);
516 		switch (type) {
517 		case MLD_LISTENER_QUERY:
518 			icmp6_ifstat_inc(outif, ifs6_out_mldquery);
519 			break;
520 		case MLD_LISTENER_REPORT:
521 			icmp6_ifstat_inc(outif, ifs6_out_mldreport);
522 			break;
523 		case MLD_LISTENER_DONE:
524 			icmp6_ifstat_inc(outif, ifs6_out_mlddone);
525 			break;
526 		}
527 	}
528 }
529 
530 /*
531  * Add an address to the list of IP6 multicast addresses for a given interface.
532  * Add source addresses to the list also, if upstream router is MLDv2 capable
533  * and the number of source is not 0.
534  */
535 struct in6_multi *
536 in6_addmulti(struct in6_addr *maddr6, struct ifnet *ifp,
537     int *errorp, int delay)
538 {
539 	struct in6_multi *in6m;
540 
541 	*errorp = 0;
542 	in6m = NULL;
543 
544 	IFF_LOCKGIANT(ifp);
545 	/*IN6_MULTI_LOCK();*/
546 
547 	IN6_LOOKUP_MULTI(*maddr6, ifp, in6m);
548 	if (in6m != NULL) {
549 		/*
550 		 * If we already joined this group, just bump the
551 		 * refcount and return it.
552 		 */
553 		KASSERT(in6m->in6m_refcount >= 1,
554 		    ("%s: bad refcount %d", __func__, in6m->in6m_refcount));
555 		++in6m->in6m_refcount;
556 	} else do {
557 		struct in6_multi *nin6m;
558 		struct ifmultiaddr *ifma;
559 		struct sockaddr_in6 sa6;
560 
561 		bzero(&sa6, sizeof(sa6));
562 		sa6.sin6_family = AF_INET6;
563 		sa6.sin6_len = sizeof(struct sockaddr_in6);
564 		sa6.sin6_addr = *maddr6;
565 
566 		*errorp = if_addmulti(ifp, (struct sockaddr *)&sa6, &ifma);
567 		if (*errorp)
568 			break;
569 
570 		/*
571 		 * If ifma->ifma_protospec is null, then if_addmulti() created
572 		 * a new record.  Otherwise, bump refcount, and we are done.
573 		 */
574 		if (ifma->ifma_protospec != NULL) {
575 			in6m = ifma->ifma_protospec;
576 			++in6m->in6m_refcount;
577 			break;
578 		}
579 
580 		nin6m = malloc(sizeof(*nin6m), M_IP6MADDR, M_NOWAIT | M_ZERO);
581 		if (nin6m == NULL) {
582 			if_delmulti_ifma(ifma);
583 			break;
584 		}
585 
586 		nin6m->in6m_addr = *maddr6;
587 		nin6m->in6m_ifp = ifp;
588 		nin6m->in6m_refcount = 1;
589 		nin6m->in6m_ifma = ifma;
590 		ifma->ifma_protospec = nin6m;
591 
592 		nin6m->in6m_timer_ch = malloc(sizeof(*nin6m->in6m_timer_ch),
593 		    M_IP6MADDR, M_NOWAIT);
594 		if (nin6m->in6m_timer_ch == NULL) {
595 			free(nin6m, M_IP6MADDR);
596 			if_delmulti_ifma(ifma);
597 			break;
598 		}
599 
600 		LIST_INSERT_HEAD(&in6_multihead, nin6m, in6m_entry);
601 
602 		callout_init(nin6m->in6m_timer_ch, 0);
603 		nin6m->in6m_timer = delay;
604 		if (nin6m->in6m_timer > 0) {
605 			nin6m->in6m_state = MLD_REPORTPENDING;
606 			mld_starttimer(nin6m);
607 		}
608 
609 		mld6_start_listening(nin6m);
610 
611 		in6m = nin6m;
612 
613 	} while (0);
614 
615 	/*IN6_MULTI_UNLOCK();*/
616 	IFF_UNLOCKGIANT(ifp);
617 
618 	return (in6m);
619 }
620 
621 /*
622  * Delete a multicast address record.
623  *
624  * TODO: Locking, as per netinet.
625  */
626 void
627 in6_delmulti(struct in6_multi *in6m)
628 {
629 	struct ifmultiaddr *ifma;
630 
631 	KASSERT(in6m->in6m_refcount >= 1, ("%s: freeing freed in6m", __func__));
632 
633 	if (--in6m->in6m_refcount == 0) {
634 		mld_stoptimer(in6m);
635 		mld6_stop_listening(in6m);
636 
637 		ifma = in6m->in6m_ifma;
638 		KASSERT(ifma->ifma_protospec == in6m,
639 		    ("%s: ifma_protospec != in6m", __func__));
640 		ifma->ifma_protospec = NULL;
641 
642 		LIST_REMOVE(in6m, in6m_entry);
643 		free(in6m->in6m_timer_ch, M_IP6MADDR);
644 		free(in6m, M_IP6MADDR);
645 
646 		if_delmulti_ifma(ifma);
647 	}
648 }
649