xref: /freebsd/sys/netinet6/mld6.c (revision e4e9813eb92cd7c4d4b819a8fbed5cbd3d92f5d8)
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 #include <net/net_osdep.h>
93 
94 /*
95  * Protocol constants
96  */
97 
98 /* denotes that the MLD max response delay field specifies time in milliseconds */
99 #define MLD_TIMER_SCALE	1000
100 /*
101  * time between repetitions of a node's initial report of interest in a
102  * multicast address(in seconds)
103  */
104 #define MLD_UNSOLICITED_REPORT_INTERVAL	10
105 
106 static struct ip6_pktopts ip6_opts;
107 
108 static void mld6_sendpkt(struct in6_multi *, int, const struct in6_addr *);
109 static void mld_starttimer(struct in6_multi *);
110 static void mld_stoptimer(struct in6_multi *);
111 static void mld_timeo(struct in6_multi *);
112 static u_long mld_timerresid(struct in6_multi *);
113 
114 void
115 mld6_init()
116 {
117 	static u_int8_t hbh_buf[8];
118 	struct ip6_hbh *hbh = (struct ip6_hbh *)hbh_buf;
119 	u_int16_t rtalert_code = htons((u_int16_t)IP6OPT_RTALERT_MLD);
120 
121 	/* ip6h_nxt will be fill in later */
122 	hbh->ip6h_len = 0;	/* (8 >> 3) - 1 */
123 
124 	/* XXX: grotty hard coding... */
125 	hbh_buf[2] = IP6OPT_PADN;	/* 2 byte padding */
126 	hbh_buf[3] = 0;
127 	hbh_buf[4] = IP6OPT_ROUTER_ALERT;
128 	hbh_buf[5] = IP6OPT_RTALERT_LEN - 2;
129 	bcopy((caddr_t)&rtalert_code, &hbh_buf[6], sizeof(u_int16_t));
130 
131 	ip6_initpktopts(&ip6_opts);
132 	ip6_opts.ip6po_hbh = hbh;
133 }
134 
135 static void
136 mld_starttimer(in6m)
137 	struct in6_multi *in6m;
138 {
139 	struct timeval now;
140 
141 	microtime(&now);
142 	in6m->in6m_timer_expire.tv_sec = now.tv_sec + in6m->in6m_timer / hz;
143 	in6m->in6m_timer_expire.tv_usec = now.tv_usec +
144 	    (in6m->in6m_timer % hz) * (1000000 / hz);
145 	if (in6m->in6m_timer_expire.tv_usec > 1000000) {
146 		in6m->in6m_timer_expire.tv_sec++;
147 		in6m->in6m_timer_expire.tv_usec -= 1000000;
148 	}
149 
150 	/* start or restart the timer */
151 	callout_reset(in6m->in6m_timer_ch, in6m->in6m_timer,
152 	    (void (*) __P((void *)))mld_timeo, in6m);
153 }
154 
155 static void
156 mld_stoptimer(in6m)
157 	struct in6_multi *in6m;
158 {
159 	if (in6m->in6m_timer == IN6M_TIMER_UNDEF)
160 		return;
161 
162 	callout_stop(in6m->in6m_timer_ch);
163 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
164 }
165 
166 static void
167 mld_timeo(in6m)
168 	struct in6_multi *in6m;
169 {
170 	int s = splnet();
171 
172 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
173 
174 	callout_stop(in6m->in6m_timer_ch);
175 
176 	switch (in6m->in6m_state) {
177 	case MLD_REPORTPENDING:
178 		mld6_start_listening(in6m);
179 		break;
180 	default:
181 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
182 		break;
183 	}
184 
185 	splx(s);
186 }
187 
188 static u_long
189 mld_timerresid(in6m)
190 	struct in6_multi *in6m;
191 {
192 	struct timeval now, diff;
193 
194 	microtime(&now);
195 
196 	if (now.tv_sec > in6m->in6m_timer_expire.tv_sec ||
197 	    (now.tv_sec == in6m->in6m_timer_expire.tv_sec &&
198 	    now.tv_usec > in6m->in6m_timer_expire.tv_usec)) {
199 		return (0);
200 	}
201 	diff = in6m->in6m_timer_expire;
202 	diff.tv_sec -= now.tv_sec;
203 	diff.tv_usec -= now.tv_usec;
204 	if (diff.tv_usec < 0) {
205 		diff.tv_sec--;
206 		diff.tv_usec += 1000000;
207 	}
208 
209 	/* return the remaining time in milliseconds */
210 	return (((u_long)(diff.tv_sec * 1000000 + diff.tv_usec)) / 1000);
211 }
212 
213 void
214 mld6_start_listening(in6m)
215 	struct in6_multi *in6m;
216 {
217 	struct in6_addr all_in6;
218 	int s = splnet();
219 
220 	/*
221 	 * RFC2710 page 10:
222 	 * The node never sends a Report or Done for the link-scope all-nodes
223 	 * address.
224 	 * MLD messages are never sent for multicast addresses whose scope is 0
225 	 * (reserved) or 1 (node-local).
226 	 */
227 	all_in6 = in6addr_linklocal_allnodes;
228 	if (in6_setscope(&all_in6, in6m->in6m_ifp, NULL)) {
229 		/* XXX: this should not happen! */
230 		in6m->in6m_timer = 0;
231 		in6m->in6m_state = MLD_OTHERLISTENER;
232 	}
233 	if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
234 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
235 	    IPV6_ADDR_SCOPE_LINKLOCAL) {
236 		in6m->in6m_timer = 0;
237 		in6m->in6m_state = MLD_OTHERLISTENER;
238 	} else {
239 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
240 		in6m->in6m_timer = arc4random() %
241 			MLD_UNSOLICITED_REPORT_INTERVAL * hz;
242 		in6m->in6m_state = MLD_IREPORTEDLAST;
243 
244 		mld_starttimer(in6m);
245 	}
246 	splx(s);
247 }
248 
249 void
250 mld6_stop_listening(in6m)
251 	struct in6_multi *in6m;
252 {
253 	struct in6_addr allnode, allrouter;
254 
255 	allnode = in6addr_linklocal_allnodes;
256 	if (in6_setscope(&allnode, in6m->in6m_ifp, NULL)) {
257 		/* XXX: this should not happen! */
258 		return;
259 	}
260 	allrouter = in6addr_linklocal_allrouters;
261 	if (in6_setscope(&allrouter, in6m->in6m_ifp, NULL)) {
262 		/* XXX impossible */
263 		return;
264 	}
265 	if (in6m->in6m_state == MLD_IREPORTEDLAST &&
266 	    !IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &allnode) &&
267 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) >
268 	    IPV6_ADDR_SCOPE_INTFACELOCAL) {
269 		mld6_sendpkt(in6m, MLD_LISTENER_DONE, &allrouter);
270 	}
271 }
272 
273 void
274 mld6_input(m, off)
275 	struct mbuf *m;
276 	int off;
277 {
278 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
279 	struct mld_hdr *mldh;
280 	struct ifnet *ifp = m->m_pkthdr.rcvif;
281 	struct in6_multi *in6m;
282 	struct in6_addr mld_addr, all_in6;
283 	struct in6_ifaddr *ia;
284 	struct ifmultiaddr *ifma;
285 	int timer;		/* timer value in the MLD query header */
286 
287 #ifndef PULLDOWN_TEST
288 	IP6_EXTHDR_CHECK(m, off, sizeof(*mldh),);
289 	mldh = (struct mld_hdr *)(mtod(m, caddr_t) + off);
290 #else
291 	IP6_EXTHDR_GET(mldh, struct mld_hdr *, m, off, sizeof(*mldh));
292 	if (mldh == NULL) {
293 		icmp6stat.icp6s_tooshort++;
294 		return;
295 	}
296 #endif
297 
298 	/* source address validation */
299 	ip6 = mtod(m, struct ip6_hdr *); /* in case mpullup */
300 	if (!IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src)) {
301 		log(LOG_ERR,
302 		    "mld6_input: src %s is not link-local (grp=%s)\n",
303 		    ip6_sprintf(&ip6->ip6_src),
304 		    ip6_sprintf(&mldh->mld_addr));
305 		/*
306 		 * spec (RFC2710) does not explicitly
307 		 * specify to discard the packet from a non link-local
308 		 * source address. But we believe it's expected to do so.
309 		 * XXX: do we have to allow :: as source?
310 		 */
311 		m_freem(m);
312 		return;
313 	}
314 
315 	/*
316 	 * make a copy for local work (in6_setscope() may modify the 1st arg)
317 	 */
318 	mld_addr = mldh->mld_addr;
319 	if (in6_setscope(&mld_addr, ifp, NULL)) {
320 		/* XXX: this should not happen! */
321 		m_free(m);
322 		return;
323 	}
324 
325 	/*
326 	 * In the MLD6 specification, there are 3 states and a flag.
327 	 *
328 	 * In Non-Listener state, we simply don't have a membership record.
329 	 * In Delaying Listener state, our timer is running (in6m->in6m_timer)
330 	 * In Idle Listener state, our timer is not running
331 	 * (in6m->in6m_timer==IN6M_TIMER_UNDEF)
332 	 *
333 	 * The flag is in6m->in6m_state, it is set to MLD_OTHERLISTENER if
334 	 * we have heard a report from another member, or MLD_IREPORTEDLAST
335 	 * if we sent the last report.
336 	 */
337 	switch(mldh->mld_type) {
338 	case MLD_LISTENER_QUERY:
339 		if (ifp->if_flags & IFF_LOOPBACK)
340 			break;
341 
342 		if (!IN6_IS_ADDR_UNSPECIFIED(&mld_addr) &&
343 		    !IN6_IS_ADDR_MULTICAST(&mld_addr))
344 			break;	/* print error or log stat? */
345 
346 		all_in6 = in6addr_linklocal_allnodes;
347 		if (in6_setscope(&all_in6, ifp, NULL)) {
348 			/* XXX: this should not happen! */
349 			break;
350 		}
351 
352 		/*
353 		 * - Start the timers in all of our membership records
354 		 *   that the query applies to for the interface on
355 		 *   which the query arrived excl. those that belong
356 		 *   to the "all-nodes" group (ff02::1).
357 		 * - Restart any timer that is already running but has
358 		 *   A value longer than the requested timeout.
359 		 * - Use the value specified in the query message as
360 		 *   the maximum timeout.
361 		 */
362 		timer = ntohs(mldh->mld_maxdelay);
363 
364 		IFP_TO_IA6(ifp, ia);
365 		if (ia == NULL)
366 			break;
367 
368 		/*
369 		 * XXX: System timer resolution is too low to handle Max
370 		 * Response Delay, so set 1 to the internal timer even if
371 		 * the calculated value equals to zero when Max Response
372 		 * Delay is positive.
373 		 */
374 		timer = ntohs(mldh->mld_maxdelay) * PR_FASTHZ / MLD_TIMER_SCALE;
375 		if (timer == 0 && mldh->mld_maxdelay)
376 			timer = 1;
377 
378 		IF_ADDR_LOCK(ifp);
379 		TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
380 			if (ifma->ifma_addr->sa_family != AF_INET6)
381 				continue;
382 			in6m = (struct in6_multi *)ifma->ifma_protospec;
383 
384 			if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
385 			    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
386 			    IPV6_ADDR_SCOPE_LINKLOCAL)
387 				continue;
388 
389 			if (IN6_IS_ADDR_UNSPECIFIED(&mld_addr) ||
390 			    IN6_ARE_ADDR_EQUAL(&mld_addr, &in6m->in6m_addr)) {
391 				if (timer == 0) {
392 					/* send a report immediately */
393 					mld_stoptimer(in6m);
394 					mld6_sendpkt(in6m, MLD_LISTENER_REPORT,
395 						NULL);
396 					in6m->in6m_timer = 0; /* reset timer */
397 					in6m->in6m_state = MLD_IREPORTEDLAST;
398 				}
399 				else if (in6m->in6m_timer == IN6M_TIMER_UNDEF ||
400 				    mld_timerresid(in6m) > (u_long)timer) {
401 					in6m->in6m_timer = arc4random() %
402 					    (int)((long)(timer * hz) / 1000);
403 					mld_starttimer(in6m);
404 				}
405 			}
406 		}
407 		IF_ADDR_UNLOCK(ifp);
408 		break;
409 
410 	case MLD_LISTENER_REPORT:
411 		/*
412 		 * For fast leave to work, we have to know that we are the
413 		 * last person to send a report for this group.  Reports
414 		 * can potentially get looped back if we are a multicast
415 		 * router, so discard reports sourced by me.
416 		 * Note that it is impossible to check IFF_LOOPBACK flag of
417 		 * ifp for this purpose, since ip6_mloopback pass the physical
418 		 * interface to looutput.
419 		 */
420 		if (m->m_flags & M_LOOP) /* XXX: grotty flag, but efficient */
421 			break;
422 
423 		if (!IN6_IS_ADDR_MULTICAST(&mld_addr))
424 			break;
425 
426 		/*
427 		 * If we belong to the group being reported, stop
428 		 * our timer for that group.
429 		 */
430 		IN6_LOOKUP_MULTI(mld_addr, ifp, in6m);
431 		if (in6m) {
432 			in6m->in6m_timer = 0; /* transit to idle state */
433 			in6m->in6m_state = MLD_OTHERLISTENER; /* clear flag */
434 		}
435 		break;
436 	default:		/* this is impossible */
437 		log(LOG_ERR, "mld6_input: illegal type(%d)", mldh->mld_type);
438 		break;
439 	}
440 
441 	m_freem(m);
442 }
443 
444 static void
445 mld6_sendpkt(in6m, type, dst)
446 	struct in6_multi *in6m;
447 	int type;
448 	const struct in6_addr *dst;
449 {
450 	struct mbuf *mh, *md;
451 	struct mld_hdr *mldh;
452 	struct ip6_hdr *ip6;
453 	struct ip6_moptions im6o;
454 	struct in6_ifaddr *ia;
455 	struct ifnet *ifp = in6m->in6m_ifp;
456 	struct ifnet *outif = NULL;
457 
458 	/*
459 	 * At first, find a link local address on the outgoing interface
460 	 * to use as the source address of the MLD packet.
461 	 */
462 	if ((ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST))
463 	    == NULL)
464 		return;
465 
466 	/*
467 	 * Allocate mbufs to store ip6 header and MLD header.
468 	 * We allocate 2 mbufs and make chain in advance because
469 	 * it is more convenient when inserting the hop-by-hop option later.
470 	 */
471 	MGETHDR(mh, M_DONTWAIT, MT_HEADER);
472 	if (mh == NULL)
473 		return;
474 	MGET(md, M_DONTWAIT, MT_DATA);
475 	if (md == NULL) {
476 		m_free(mh);
477 		return;
478 	}
479 	mh->m_next = md;
480 
481 	mh->m_pkthdr.rcvif = NULL;
482 	mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
483 	mh->m_len = sizeof(struct ip6_hdr);
484 	MH_ALIGN(mh, sizeof(struct ip6_hdr));
485 
486 	/* fill in the ip6 header */
487 	ip6 = mtod(mh, struct ip6_hdr *);
488 	ip6->ip6_flow = 0;
489 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
490 	ip6->ip6_vfc |= IPV6_VERSION;
491 	/* ip6_plen will be set later */
492 	ip6->ip6_nxt = IPPROTO_ICMPV6;
493 	/* ip6_hlim will be set by im6o.im6o_multicast_hlim */
494 	ip6->ip6_src = ia->ia_addr.sin6_addr;
495 	ip6->ip6_dst = dst ? *dst : in6m->in6m_addr;
496 
497 	/* fill in the MLD header */
498 	md->m_len = sizeof(struct mld_hdr);
499 	mldh = mtod(md, struct mld_hdr *);
500 	mldh->mld_type = type;
501 	mldh->mld_code = 0;
502 	mldh->mld_cksum = 0;
503 	/* XXX: we assume the function will not be called for query messages */
504 	mldh->mld_maxdelay = 0;
505 	mldh->mld_reserved = 0;
506 	mldh->mld_addr = in6m->in6m_addr;
507 	in6_clearscope(&mldh->mld_addr); /* XXX */
508 	mldh->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6, sizeof(struct ip6_hdr),
509 				    sizeof(struct mld_hdr));
510 
511 	/* construct multicast option */
512 	bzero(&im6o, sizeof(im6o));
513 	im6o.im6o_multicast_ifp = ifp;
514 	im6o.im6o_multicast_hlim = 1;
515 
516 	/*
517 	 * Request loopback of the report if we are acting as a multicast
518 	 * router, so that the process-level routing daemon can hear it.
519 	 */
520 	im6o.im6o_multicast_loop = (ip6_mrouter != NULL);
521 
522 	/* increment output statictics */
523 	icmp6stat.icp6s_outhist[type]++;
524 
525 	ip6_output(mh, &ip6_opts, NULL, 0, &im6o, &outif, NULL);
526 	if (outif) {
527 		icmp6_ifstat_inc(outif, ifs6_out_msg);
528 		switch (type) {
529 		case MLD_LISTENER_QUERY:
530 			icmp6_ifstat_inc(outif, ifs6_out_mldquery);
531 			break;
532 		case MLD_LISTENER_REPORT:
533 			icmp6_ifstat_inc(outif, ifs6_out_mldreport);
534 			break;
535 		case MLD_LISTENER_DONE:
536 			icmp6_ifstat_inc(outif, ifs6_out_mlddone);
537 			break;
538 		}
539 	}
540 }
541 
542 /*
543  * Add an address to the list of IP6 multicast addresses for a given interface.
544  * Add source addresses to the list also, if upstream router is MLDv2 capable
545  * and the number of source is not 0.
546  */
547 struct	in6_multi *
548 in6_addmulti(maddr6, ifp, errorp, delay)
549 	struct in6_addr *maddr6;
550 	struct ifnet *ifp;
551 	int *errorp, delay;
552 {
553 	struct in6_multi *in6m;
554 	struct ifmultiaddr *ifma;
555 	struct sockaddr_in6 sa6;
556 	int	s = splnet();
557 
558 	*errorp = 0;
559 
560 	/*
561 	 * Call generic routine to add membership or increment
562 	 * refcount.  It wants addresses in the form of a sockaddr,
563 	 * so we build one here (being careful to zero the unused bytes).
564 	 */
565 	bzero(&sa6, sizeof(sa6));
566 	sa6.sin6_family = AF_INET6;
567 	sa6.sin6_len = sizeof(struct sockaddr_in6);
568 	sa6.sin6_addr = *maddr6;
569 	*errorp = if_addmulti(ifp, (struct sockaddr *)&sa6, &ifma);
570 	if (*errorp) {
571 		splx(s);
572 		return 0;
573 	}
574 
575 	/*
576 	 * If ifma->ifma_protospec is null, then if_addmulti() created
577 	 * a new record.  Otherwise, we are done.
578 	 */
579 	if (ifma->ifma_protospec != NULL) {
580 		splx(s);
581 		return ifma->ifma_protospec;
582 	}
583 
584 	/* XXX - if_addmulti uses M_WAITOK.  Can this really be called
585 	   at interrupt time?  If so, need to fix if_addmulti. XXX */
586 	in6m = (struct in6_multi *)malloc(sizeof(*in6m), M_IP6MADDR, M_NOWAIT);
587 	if (in6m == NULL) {
588 		splx(s);
589 		return (NULL);
590 	}
591 
592 	bzero(in6m, sizeof *in6m);
593 	in6m->in6m_addr = *maddr6;
594 	in6m->in6m_ifp = ifp;
595 	in6m->in6m_refcount = 1;
596 	in6m->in6m_ifma = ifma;
597 	ifma->ifma_protospec = in6m;
598 	in6m->in6m_timer_ch = malloc(sizeof(*in6m->in6m_timer_ch), M_IP6MADDR,
599 	    M_NOWAIT);
600 	if (in6m->in6m_timer_ch == NULL) {
601 		free(in6m, M_IP6MADDR);
602 		splx(s);
603 		return (NULL);
604 	}
605 	LIST_INSERT_HEAD(&in6_multihead, in6m, in6m_entry);
606 
607 	callout_init(in6m->in6m_timer_ch, 0);
608 	in6m->in6m_timer = delay;
609 	if (in6m->in6m_timer > 0) {
610 		in6m->in6m_state = MLD_REPORTPENDING;
611 		mld_starttimer(in6m);
612 
613 		splx(s);
614 		return (in6m);
615 	}
616 
617 	/*
618 	 * Let MLD6 know that we have joined a new IPv6 multicast
619 	 * group.
620 	 */
621 	mld6_start_listening(in6m);
622 	splx(s);
623 	return (in6m);
624 }
625 
626 /*
627  * Delete a multicast address record.
628  */
629 void
630 in6_delmulti(in6m)
631 	struct in6_multi *in6m;
632 {
633 	struct ifmultiaddr *ifma = in6m->in6m_ifma;
634 	int	s = splnet();
635 
636 	if (ifma->ifma_refcount == 1) {
637 		/*
638 		 * No remaining claims to this record; let MLD6 know
639 		 * that we are leaving the multicast group.
640 		 */
641 		mld_stoptimer(in6m);
642 		mld6_stop_listening(in6m);
643 		ifma->ifma_protospec = NULL;
644 		LIST_REMOVE(in6m, in6m_entry);
645 		free(in6m->in6m_timer_ch, M_IP6MADDR);
646 		free(in6m, M_IP6MADDR);
647 	}
648 	/* XXX - should be separate API for when we have an ifma? */
649 	if_delmulti(ifma->ifma_ifp, ifma->ifma_addr);
650 	splx(s);
651 }
652