xref: /freebsd/sys/netinet6/mld6.c (revision 6356dba0b403daa023dec24559ab1f8e602e4f14)
1 /*-
2  * Copyright (C) 1998 WIDE Project.
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. Neither the name of the project nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	$KAME: mld6.c,v 1.27 2001/04/04 05:17:30 itojun Exp $
30  */
31 
32 /*-
33  * Copyright (c) 1988 Stephen Deering.
34  * Copyright (c) 1992, 1993
35  *	The Regents of the University of California.  All rights reserved.
36  *
37  * This code is derived from software contributed to Berkeley by
38  * Stephen Deering of Stanford University.
39  *
40  * Redistribution and use in source and binary forms, with or without
41  * modification, are permitted provided that the following conditions
42  * are met:
43  * 1. Redistributions of source code must retain the above copyright
44  *    notice, this list of conditions and the following disclaimer.
45  * 2. Redistributions in binary form must reproduce the above copyright
46  *    notice, this list of conditions and the following disclaimer in the
47  *    documentation and/or other materials provided with the distribution.
48  * 4. Neither the name of the University nor the names of its contributors
49  *    may be used to endorse or promote products derived from this software
50  *    without specific prior written permission.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62  * SUCH DAMAGE.
63  *
64  *	@(#)igmp.c	8.1 (Berkeley) 7/19/93
65  */
66 
67 #include <sys/cdefs.h>
68 __FBSDID("$FreeBSD$");
69 
70 #include "opt_inet.h"
71 #include "opt_inet6.h"
72 
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/mbuf.h>
76 #include <sys/socket.h>
77 #include <sys/protosw.h>
78 #include <sys/syslog.h>
79 #include <sys/kernel.h>
80 #include <sys/callout.h>
81 #include <sys/malloc.h>
82 #include <sys/vimage.h>
83 
84 #include <net/if.h>
85 
86 #include <netinet/in.h>
87 #include <netinet/in_var.h>
88 #include <netinet6/in6_var.h>
89 #include <netinet/ip6.h>
90 #include <netinet6/ip6_var.h>
91 #include <netinet6/scope6_var.h>
92 #include <netinet/icmp6.h>
93 #include <netinet6/mld6_var.h>
94 
95 /*
96  * Protocol constants
97  */
98 
99 /* denotes that the MLD max response delay field specifies time in milliseconds */
100 #define MLD_TIMER_SCALE	1000
101 /*
102  * time between repetitions of a node's initial report of interest in a
103  * multicast address(in seconds)
104  */
105 #define MLD_UNSOLICITED_REPORT_INTERVAL	10
106 
107 static struct ip6_pktopts ip6_opts;
108 
109 static void mld6_sendpkt(struct in6_multi *, int, const struct in6_addr *);
110 static void mld_starttimer(struct in6_multi *);
111 static void mld_stoptimer(struct in6_multi *);
112 static void mld_timeo(struct in6_multi *);
113 static u_long mld_timerresid(struct in6_multi *);
114 
115 void
116 mld6_init(void)
117 {
118 	static u_int8_t hbh_buf[8];
119 	struct ip6_hbh *hbh = (struct ip6_hbh *)hbh_buf;
120 	u_int16_t rtalert_code = htons((u_int16_t)IP6OPT_RTALERT_MLD);
121 
122 	/* ip6h_nxt will be fill in later */
123 	hbh->ip6h_len = 0;	/* (8 >> 3) - 1 */
124 
125 	/* XXX: grotty hard coding... */
126 	hbh_buf[2] = IP6OPT_PADN;	/* 2 byte padding */
127 	hbh_buf[3] = 0;
128 	hbh_buf[4] = IP6OPT_ROUTER_ALERT;
129 	hbh_buf[5] = IP6OPT_RTALERT_LEN - 2;
130 	bcopy((caddr_t)&rtalert_code, &hbh_buf[6], sizeof(u_int16_t));
131 
132 	ip6_initpktopts(&V_ip6_opts);
133 	V_ip6_opts.ip6po_hbh = hbh;
134 }
135 
136 static void
137 mld_starttimer(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 (*)(void *))mld_timeo, in6m);
153 }
154 
155 static void
156 mld_stoptimer(struct in6_multi *in6m)
157 {
158 	if (in6m->in6m_timer == IN6M_TIMER_UNDEF)
159 		return;
160 
161 	callout_stop(in6m->in6m_timer_ch);
162 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
163 }
164 
165 static void
166 mld_timeo(struct in6_multi *in6m)
167 {
168 	int s = splnet();
169 
170 	in6m->in6m_timer = IN6M_TIMER_UNDEF;
171 
172 	callout_stop(in6m->in6m_timer_ch);
173 
174 	switch (in6m->in6m_state) {
175 	case MLD_REPORTPENDING:
176 		mld6_start_listening(in6m);
177 		break;
178 	default:
179 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
180 		break;
181 	}
182 
183 	splx(s);
184 }
185 
186 static u_long
187 mld_timerresid(struct in6_multi *in6m)
188 {
189 	struct timeval now, diff;
190 
191 	microtime(&now);
192 
193 	if (now.tv_sec > in6m->in6m_timer_expire.tv_sec ||
194 	    (now.tv_sec == in6m->in6m_timer_expire.tv_sec &&
195 	    now.tv_usec > in6m->in6m_timer_expire.tv_usec)) {
196 		return (0);
197 	}
198 	diff = in6m->in6m_timer_expire;
199 	diff.tv_sec -= now.tv_sec;
200 	diff.tv_usec -= now.tv_usec;
201 	if (diff.tv_usec < 0) {
202 		diff.tv_sec--;
203 		diff.tv_usec += 1000000;
204 	}
205 
206 	/* return the remaining time in milliseconds */
207 	return (((u_long)(diff.tv_sec * 1000000 + diff.tv_usec)) / 1000);
208 }
209 
210 void
211 mld6_start_listening(struct in6_multi *in6m)
212 {
213 	struct in6_addr all_in6;
214 	int s = splnet();
215 
216 	/*
217 	 * RFC2710 page 10:
218 	 * The node never sends a Report or Done for the link-scope all-nodes
219 	 * address.
220 	 * MLD messages are never sent for multicast addresses whose scope is 0
221 	 * (reserved) or 1 (node-local).
222 	 */
223 	all_in6 = in6addr_linklocal_allnodes;
224 	if (in6_setscope(&all_in6, in6m->in6m_ifp, NULL)) {
225 		/* XXX: this should not happen! */
226 		in6m->in6m_timer = 0;
227 		in6m->in6m_state = MLD_OTHERLISTENER;
228 	}
229 	if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
230 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
231 	    IPV6_ADDR_SCOPE_LINKLOCAL) {
232 		in6m->in6m_timer = 0;
233 		in6m->in6m_state = MLD_OTHERLISTENER;
234 	} else {
235 		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
236 		in6m->in6m_timer = arc4random() %
237 			MLD_UNSOLICITED_REPORT_INTERVAL * hz;
238 		in6m->in6m_state = MLD_IREPORTEDLAST;
239 
240 		mld_starttimer(in6m);
241 	}
242 	splx(s);
243 }
244 
245 void
246 mld6_stop_listening(struct in6_multi *in6m)
247 {
248 	struct in6_addr allnode, allrouter;
249 
250 	allnode = in6addr_linklocal_allnodes;
251 	if (in6_setscope(&allnode, in6m->in6m_ifp, NULL)) {
252 		/* XXX: this should not happen! */
253 		return;
254 	}
255 	allrouter = in6addr_linklocal_allrouters;
256 	if (in6_setscope(&allrouter, in6m->in6m_ifp, NULL)) {
257 		/* XXX impossible */
258 		return;
259 	}
260 	if (in6m->in6m_state == MLD_IREPORTEDLAST &&
261 	    !IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &allnode) &&
262 	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) >
263 	    IPV6_ADDR_SCOPE_INTFACELOCAL) {
264 		mld6_sendpkt(in6m, MLD_LISTENER_DONE, &allrouter);
265 	}
266 }
267 
268 void
269 mld6_input(struct mbuf *m, int off)
270 {
271 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
272 	struct mld_hdr *mldh;
273 	struct ifnet *ifp = m->m_pkthdr.rcvif;
274 	struct in6_multi *in6m;
275 	struct in6_addr mld_addr, all_in6;
276 	struct in6_ifaddr *ia;
277 	struct ifmultiaddr *ifma;
278 	int timer;		/* timer value in the MLD query header */
279 
280 #ifndef PULLDOWN_TEST
281 	IP6_EXTHDR_CHECK(m, off, sizeof(*mldh),);
282 	mldh = (struct mld_hdr *)(mtod(m, caddr_t) + off);
283 #else
284 	IP6_EXTHDR_GET(mldh, struct mld_hdr *, m, off, sizeof(*mldh));
285 	if (mldh == NULL) {
286 		V_icmp6stat.icp6s_tooshort++;
287 		return;
288 	}
289 #endif
290 
291 	/* source address validation */
292 	ip6 = mtod(m, struct ip6_hdr *); /* in case mpullup */
293 	if (!IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src)) {
294 		char ip6bufs[INET6_ADDRSTRLEN], ip6bufg[INET6_ADDRSTRLEN];
295 		log(LOG_ERR,
296 		    "mld6_input: src %s is not link-local (grp=%s)\n",
297 		    ip6_sprintf(ip6bufs, &ip6->ip6_src),
298 		    ip6_sprintf(ip6bufg, &mldh->mld_addr));
299 		/*
300 		 * spec (RFC2710) does not explicitly
301 		 * specify to discard the packet from a non link-local
302 		 * source address. But we believe it's expected to do so.
303 		 * XXX: do we have to allow :: as source?
304 		 */
305 		m_freem(m);
306 		return;
307 	}
308 
309 	/*
310 	 * make a copy for local work (in6_setscope() may modify the 1st arg)
311 	 */
312 	mld_addr = mldh->mld_addr;
313 	if (in6_setscope(&mld_addr, ifp, NULL)) {
314 		/* XXX: this should not happen! */
315 		m_free(m);
316 		return;
317 	}
318 
319 	/*
320 	 * In the MLD6 specification, there are 3 states and a flag.
321 	 *
322 	 * In Non-Listener state, we simply don't have a membership record.
323 	 * In Delaying Listener state, our timer is running (in6m->in6m_timer)
324 	 * In Idle Listener state, our timer is not running
325 	 * (in6m->in6m_timer==IN6M_TIMER_UNDEF)
326 	 *
327 	 * The flag is in6m->in6m_state, it is set to MLD_OTHERLISTENER if
328 	 * we have heard a report from another member, or MLD_IREPORTEDLAST
329 	 * if we sent the last report.
330 	 */
331 	switch(mldh->mld_type) {
332 	case MLD_LISTENER_QUERY:
333 		if (ifp->if_flags & IFF_LOOPBACK)
334 			break;
335 
336 		if (!IN6_IS_ADDR_UNSPECIFIED(&mld_addr) &&
337 		    !IN6_IS_ADDR_MULTICAST(&mld_addr))
338 			break;	/* print error or log stat? */
339 
340 		all_in6 = in6addr_linklocal_allnodes;
341 		if (in6_setscope(&all_in6, ifp, NULL)) {
342 			/* XXX: this should not happen! */
343 			break;
344 		}
345 
346 		/*
347 		 * - Start the timers in all of our membership records
348 		 *   that the query applies to for the interface on
349 		 *   which the query arrived excl. those that belong
350 		 *   to the "all-nodes" group (ff02::1).
351 		 * - Restart any timer that is already running but has
352 		 *   A value longer than the requested timeout.
353 		 * - Use the value specified in the query message as
354 		 *   the maximum timeout.
355 		 */
356 		timer = ntohs(mldh->mld_maxdelay);
357 
358 		IFP_TO_IA6(ifp, ia);
359 		if (ia == NULL)
360 			break;
361 
362 		/*
363 		 * XXX: System timer resolution is too low to handle Max
364 		 * Response Delay, so set 1 to the internal timer even if
365 		 * the calculated value equals to zero when Max Response
366 		 * Delay is positive.
367 		 */
368 		timer = ntohs(mldh->mld_maxdelay) * PR_FASTHZ / MLD_TIMER_SCALE;
369 		if (timer == 0 && mldh->mld_maxdelay)
370 			timer = 1;
371 
372 		IF_ADDR_LOCK(ifp);
373 		TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
374 			if (ifma->ifma_addr->sa_family != AF_INET6)
375 				continue;
376 			in6m = (struct in6_multi *)ifma->ifma_protospec;
377 
378 			if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
379 			    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
380 			    IPV6_ADDR_SCOPE_LINKLOCAL)
381 				continue;
382 
383 			if (IN6_IS_ADDR_UNSPECIFIED(&mld_addr) ||
384 			    IN6_ARE_ADDR_EQUAL(&mld_addr, &in6m->in6m_addr)) {
385 				if (timer == 0) {
386 					/* send a report immediately */
387 					mld_stoptimer(in6m);
388 					mld6_sendpkt(in6m, MLD_LISTENER_REPORT,
389 						NULL);
390 					in6m->in6m_timer = 0; /* reset timer */
391 					in6m->in6m_state = MLD_IREPORTEDLAST;
392 				}
393 				else if (in6m->in6m_timer == IN6M_TIMER_UNDEF ||
394 				    mld_timerresid(in6m) > (u_long)timer) {
395 					in6m->in6m_timer = arc4random() %
396 					    (int)((long)(timer * hz) / 1000);
397 					mld_starttimer(in6m);
398 				}
399 			}
400 		}
401 		IF_ADDR_UNLOCK(ifp);
402 		break;
403 
404 	case MLD_LISTENER_REPORT:
405 		/*
406 		 * For fast leave to work, we have to know that we are the
407 		 * last person to send a report for this group.  Reports
408 		 * can potentially get looped back if we are a multicast
409 		 * router, so discard reports sourced by me.
410 		 * Note that it is impossible to check IFF_LOOPBACK flag of
411 		 * ifp for this purpose, since ip6_mloopback pass the physical
412 		 * interface to looutput.
413 		 */
414 		if (m->m_flags & M_LOOP) /* XXX: grotty flag, but efficient */
415 			break;
416 
417 		if (!IN6_IS_ADDR_MULTICAST(&mld_addr))
418 			break;
419 
420 		/*
421 		 * If we belong to the group being reported, stop
422 		 * our timer for that group.
423 		 */
424 		IN6_LOOKUP_MULTI(mld_addr, ifp, in6m);
425 		if (in6m) {
426 			in6m->in6m_timer = 0; /* transit to idle state */
427 			in6m->in6m_state = MLD_OTHERLISTENER; /* clear flag */
428 		}
429 		break;
430 	default:		/* this is impossible */
431 		log(LOG_ERR, "mld6_input: illegal type(%d)", mldh->mld_type);
432 		break;
433 	}
434 
435 	m_freem(m);
436 }
437 
438 static void
439 mld6_sendpkt(struct in6_multi *in6m, int type, const struct in6_addr *dst)
440 {
441 	struct mbuf *mh, *md;
442 	struct mld_hdr *mldh;
443 	struct ip6_hdr *ip6;
444 	struct ip6_moptions im6o;
445 	struct in6_ifaddr *ia;
446 	struct ifnet *ifp = in6m->in6m_ifp;
447 	struct ifnet *outif = NULL;
448 
449 	/*
450 	 * At first, find a link local address on the outgoing interface
451 	 * to use as the source address of the MLD packet.
452 	 */
453 	if ((ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST))
454 	    == NULL)
455 		return;
456 
457 	/*
458 	 * Allocate mbufs to store ip6 header and MLD header.
459 	 * We allocate 2 mbufs and make chain in advance because
460 	 * it is more convenient when inserting the hop-by-hop option later.
461 	 */
462 	MGETHDR(mh, M_DONTWAIT, MT_HEADER);
463 	if (mh == NULL)
464 		return;
465 	MGET(md, M_DONTWAIT, MT_DATA);
466 	if (md == NULL) {
467 		m_free(mh);
468 		return;
469 	}
470 	mh->m_next = md;
471 
472 	mh->m_pkthdr.rcvif = NULL;
473 	mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
474 	mh->m_len = sizeof(struct ip6_hdr);
475 	MH_ALIGN(mh, sizeof(struct ip6_hdr));
476 
477 	/* fill in the ip6 header */
478 	ip6 = mtod(mh, struct ip6_hdr *);
479 	ip6->ip6_flow = 0;
480 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
481 	ip6->ip6_vfc |= IPV6_VERSION;
482 	/* ip6_plen will be set later */
483 	ip6->ip6_nxt = IPPROTO_ICMPV6;
484 	/* ip6_hlim will be set by im6o.im6o_multicast_hlim */
485 	ip6->ip6_src = ia->ia_addr.sin6_addr;
486 	ip6->ip6_dst = dst ? *dst : in6m->in6m_addr;
487 
488 	/* fill in the MLD header */
489 	md->m_len = sizeof(struct mld_hdr);
490 	mldh = mtod(md, struct mld_hdr *);
491 	mldh->mld_type = type;
492 	mldh->mld_code = 0;
493 	mldh->mld_cksum = 0;
494 	/* XXX: we assume the function will not be called for query messages */
495 	mldh->mld_maxdelay = 0;
496 	mldh->mld_reserved = 0;
497 	mldh->mld_addr = in6m->in6m_addr;
498 	in6_clearscope(&mldh->mld_addr); /* XXX */
499 	mldh->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6, sizeof(struct ip6_hdr),
500 				    sizeof(struct mld_hdr));
501 
502 	/* construct multicast option */
503 	bzero(&im6o, sizeof(im6o));
504 	im6o.im6o_multicast_ifp = ifp;
505 	im6o.im6o_multicast_hlim = 1;
506 
507 	/*
508 	 * Request loopback of the report if we are acting as a multicast
509 	 * router, so that the process-level routing daemon can hear it.
510 	 */
511 	im6o.im6o_multicast_loop = (ip6_mrouter != NULL);
512 
513 	/* increment output statictics */
514 	V_icmp6stat.icp6s_outhist[type]++;
515 
516 	ip6_output(mh, &V_ip6_opts, NULL, 0, &im6o, &outif, NULL);
517 	if (outif) {
518 		icmp6_ifstat_inc(outif, ifs6_out_msg);
519 		switch (type) {
520 		case MLD_LISTENER_QUERY:
521 			icmp6_ifstat_inc(outif, ifs6_out_mldquery);
522 			break;
523 		case MLD_LISTENER_REPORT:
524 			icmp6_ifstat_inc(outif, ifs6_out_mldreport);
525 			break;
526 		case MLD_LISTENER_DONE:
527 			icmp6_ifstat_inc(outif, ifs6_out_mlddone);
528 			break;
529 		}
530 	}
531 }
532 
533 /*
534  * Add an address to the list of IP6 multicast addresses for a given interface.
535  * Add source addresses to the list also, if upstream router is MLDv2 capable
536  * and the number of source is not 0.
537  */
538 struct in6_multi *
539 in6_addmulti(struct in6_addr *maddr6, struct ifnet *ifp,
540     int *errorp, int delay)
541 {
542 	struct in6_multi *in6m;
543 
544 	*errorp = 0;
545 	in6m = NULL;
546 
547 	IFF_LOCKGIANT(ifp);
548 	/*IN6_MULTI_LOCK();*/
549 
550 	IN6_LOOKUP_MULTI(*maddr6, ifp, in6m);
551 	if (in6m != NULL) {
552 		/*
553 		 * If we already joined this group, just bump the
554 		 * refcount and return it.
555 		 */
556 		KASSERT(in6m->in6m_refcount >= 1,
557 		    ("%s: bad refcount %d", __func__, in6m->in6m_refcount));
558 		++in6m->in6m_refcount;
559 	} else do {
560 		struct in6_multi *nin6m;
561 		struct ifmultiaddr *ifma;
562 		struct sockaddr_in6 sa6;
563 
564 		bzero(&sa6, sizeof(sa6));
565 		sa6.sin6_family = AF_INET6;
566 		sa6.sin6_len = sizeof(struct sockaddr_in6);
567 		sa6.sin6_addr = *maddr6;
568 
569 		*errorp = if_addmulti(ifp, (struct sockaddr *)&sa6, &ifma);
570 		if (*errorp)
571 			break;
572 
573 		/*
574 		 * If ifma->ifma_protospec is null, then if_addmulti() created
575 		 * a new record.  Otherwise, bump refcount, and we are done.
576 		 */
577 		if (ifma->ifma_protospec != NULL) {
578 			in6m = ifma->ifma_protospec;
579 			++in6m->in6m_refcount;
580 			break;
581 		}
582 
583 		nin6m = malloc(sizeof(*nin6m), M_IP6MADDR, M_NOWAIT | M_ZERO);
584 		if (nin6m == NULL) {
585 			if_delmulti_ifma(ifma);
586 			break;
587 		}
588 
589 		nin6m->in6m_addr = *maddr6;
590 		nin6m->in6m_ifp = ifp;
591 		nin6m->in6m_refcount = 1;
592 		nin6m->in6m_ifma = ifma;
593 		ifma->ifma_protospec = nin6m;
594 
595 		nin6m->in6m_timer_ch = malloc(sizeof(*nin6m->in6m_timer_ch),
596 		    M_IP6MADDR, M_NOWAIT);
597 		if (nin6m->in6m_timer_ch == NULL) {
598 			free(nin6m, M_IP6MADDR);
599 			if_delmulti_ifma(ifma);
600 			break;
601 		}
602 
603 		LIST_INSERT_HEAD(&in6_multihead, nin6m, in6m_entry);
604 
605 		callout_init(nin6m->in6m_timer_ch, 0);
606 		nin6m->in6m_timer = delay;
607 		if (nin6m->in6m_timer > 0) {
608 			nin6m->in6m_state = MLD_REPORTPENDING;
609 			mld_starttimer(nin6m);
610 		}
611 
612 		mld6_start_listening(nin6m);
613 
614 		in6m = nin6m;
615 
616 	} while (0);
617 
618 	/*IN6_MULTI_UNLOCK();*/
619 	IFF_UNLOCKGIANT(ifp);
620 
621 	return (in6m);
622 }
623 
624 /*
625  * Delete a multicast address record.
626  *
627  * TODO: Locking, as per netinet.
628  */
629 void
630 in6_delmulti(struct in6_multi *in6m)
631 {
632 	struct ifmultiaddr *ifma;
633 
634 	KASSERT(in6m->in6m_refcount >= 1, ("%s: freeing freed in6m", __func__));
635 
636 	if (--in6m->in6m_refcount == 0) {
637 		mld_stoptimer(in6m);
638 		mld6_stop_listening(in6m);
639 
640 		ifma = in6m->in6m_ifma;
641 		KASSERT(ifma->ifma_protospec == in6m,
642 		    ("%s: ifma_protospec != in6m", __func__));
643 		ifma->ifma_protospec = NULL;
644 
645 		LIST_REMOVE(in6m, in6m_entry);
646 		free(in6m->in6m_timer_ch, M_IP6MADDR);
647 		free(in6m, M_IP6MADDR);
648 
649 		if_delmulti_ifma(ifma);
650 	}
651 }
652