Bite the bullet, and make the IPv6 SSM and MLDv2 mega-commit:

import from p4 bms_netdev.  Summary of changes:

 * Connect netinet6/in6_mcast.c to build.
   The legacy KAME KPIs are mostly preserved.
 * Eliminate now dead code from ip6_output.c.
   Don't do mbuf bingo, we are not going to do RFC 2292 style
   CMSG tricks for multicast options as they are not required
   by any current IPv6 normative reference.
 * Refactor transports (UDP, raw_ip6) to do own mcast filtering.
   SCTP, TCP unaffected by this change.
 * Add ip6_msource, in6_msource structs to in6_var.h.
 * Hookup mld_ifinfo state to in6_ifextra, allocate from
   domifattach path.
 * Eliminate IN6_LOOKUP_MULTI(), it is no longer referenced.
   Kernel consumers which need this should use in6m_lookup().
 * Refactor IPv6 socket group memberships to use a vector (like IPv4).
 * Update ifmcstat(8) for IPv6 SSM.
 * Add witness lock order for IN6_MULTI_LOCK.
 * Move IN6_MULTI_LOCK out of lower ip6_output()/ip6_input() paths.
 * Introduce IP6STAT_ADD/SUB/INC/DEC as per rwatson's IPv4 cleanup.
 * Update carp(4) for new IPv6 SSM KPIs.
 * Virtualize ip6_mrouter socket.
   Changes mostly localized to IPv6 MROUTING.
 * Don't do a local group lookup in MROUTING.
 * Kill unused KAME prototypes in6_purgemkludge(), in6_restoremkludge().
 * Preserve KAME DAD timer jitter behaviour in MLDv1 compatibility mode.
 * Bump __FreeBSD_version to 800084.
 * Update UPDATING.

NOTE WELL:
 * This code hasn't been tested against real MLDv2 queriers
   (yet), although the on-wire protocol has been verified in Wireshark.
 * There are a few unresolved issues in the socket layer APIs to
   do with scope ID propagation.
 * There is a LOR present in ip6_output()'s use of
   in6_setscope() which needs to be resolved. See comments in mld6.c.
   This is believed to be benign and can't be avoided for the moment
   without re-introducing an indirect netisr.

This work was mostly derived from the IGMPv3 implementation, and
has been sponsored by a third party.

1 files changed, 2943 insertions, 396 deletions

diff --git a/sys/netinet6/mld6.c b/sys/netinet6/mld6.c
index 0d05522..17b1df8 100644
--- a/sys/netinet6/mld6.c
+++ b/sys/netinet6/mld6.c
@@ -1,6 +1,5 @@
 /*-
- * Copyright (C) 1998 WIDE Project.
- * All rights reserved.
+ * Copyright (c) 2009 Bruce Simpson.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,14 +9,14 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the project nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
@@ -75,13 +74,16 @@ __FBSDID("$FreeBSD$");
 #include <sys/mbuf.h>
 #include <sys/socket.h>
 #include <sys/protosw.h>
-#include <sys/syslog.h>
+#include <sys/sysctl.h>
 #include <sys/kernel.h>
 #include <sys/callout.h>
 #include <sys/malloc.h>
+#include <sys/module.h>
 #include <sys/vimage.h>
 
 #include <net/if.h>
+#include <net/route.h>
+#include <net/vnet.h>
 
 #include <netinet/in.h>
 #include <netinet/in_var.h>
@@ -90,568 +92,3113 @@ __FBSDID("$FreeBSD$");
 #include <netinet6/ip6_var.h>
 #include <netinet6/scope6_var.h>
 #include <netinet/icmp6.h>
+#include <netinet6/mld6.h>
 #include <netinet6/mld6_var.h>
+#include <netinet/vinet.h>
 #include <netinet6/vinet6.h>
 
+#include <security/mac/mac_framework.h>
+
+#ifndef KTR_MLD
+#define KTR_MLD KTR_INET6
+#endif
+
+static struct mld_ifinfo *
+		mli_alloc_locked(struct ifnet *);
+static void	mli_delete_locked(const struct ifnet *);
+static void	mld_dispatch_packet(struct mbuf *);
+static void	mld_dispatch_queue(struct ifqueue *, int);
+static void	mld_final_leave(struct in6_multi *, struct mld_ifinfo *);
+static void	mld_fasttimo_vnet(void);
+static int	mld_handle_state_change(struct in6_multi *,
+		    struct mld_ifinfo *);
+static int	mld_initial_join(struct in6_multi *, struct mld_ifinfo *,
+		    const int);
+#ifdef KTR
+static char *	mld_rec_type_to_str(const int);
+#endif
+static void	mld_set_version(struct mld_ifinfo *, const int);
+static void	mld_slowtimo_vnet(void);
+static void	mld_sysinit(void);
+static void	mld_sysuninit(void);
+static int	mld_v1_input_query(struct ifnet *, const struct ip6_hdr *,
+		    const struct mld_hdr *);
+static int	mld_v1_input_report(struct ifnet *, const struct ip6_hdr *,
+		    const struct mld_hdr *);
+static void	mld_v1_process_group_timer(struct in6_multi *, const int);
+static void	mld_v1_process_querier_timers(struct mld_ifinfo *);
+static int	mld_v1_transmit_report(struct in6_multi *, const int);
+static void	mld_v1_update_group(struct in6_multi *, const int);
+static void	mld_v2_cancel_link_timers(struct mld_ifinfo *);
+static void	mld_v2_dispatch_general_query(struct mld_ifinfo *);
+static struct mbuf *
+		mld_v2_encap_report(struct ifnet *, struct mbuf *);
+static int	mld_v2_enqueue_filter_change(struct ifqueue *,
+		    struct in6_multi *);
+static int	mld_v2_enqueue_group_record(struct ifqueue *,
+		    struct in6_multi *, const int, const int, const int);
+static int	mld_v2_input_query(struct ifnet *, const struct ip6_hdr *,
+		    struct mbuf *, const int, const int);
+static int	mld_v2_merge_state_changes(struct in6_multi *,
+		    struct ifqueue *);
+static void	mld_v2_process_group_timers(struct mld_ifinfo *,
+		    struct ifqueue *, struct ifqueue *,
+		    struct in6_multi *, const int);
+static int	mld_v2_process_group_query(struct in6_multi *,
+		    struct mld_ifinfo *mli, int, struct mbuf *, const int);
+static int	sysctl_mld_gsr(SYSCTL_HANDLER_ARGS);
+static int	sysctl_mld_ifinfo(SYSCTL_HANDLER_ARGS);
+
+#ifdef VIMAGE
+static vnet_attach_fn	vnet_mld_iattach;
+static vnet_detach_fn	vnet_mld_idetach;
+#else
+static int	vnet_mld_iattach(const void *);
+static int	vnet_mld_idetach(const void *);
+#endif /* VIMAGE */
+
 /*
- * Protocol constants
+ * Normative references: RFC 2710, RFC 3590, RFC 3810.
+ *
+ * Locking:
+ *  * The MLD subsystem lock ends up being system-wide for the moment,
+ *    but could be per-VIMAGE later on.
+ *  * The permitted lock order is: IN6_MULTI_LOCK, MLD_LOCK, IF_ADDR_LOCK.
+ *    Any may be taken independently; if any are held at the same
+ *    time, the above lock order must be followed.
+ *  * IN6_MULTI_LOCK covers in_multi.
+ *  * MLD_LOCK covers per-link state and any global variables in this file.
+ *  * IF_ADDR_LOCK covers if_multiaddrs, which is used for a variety of
+ *    per-link state iterators.
+ *
+ *  XXX LOR PREVENTION
+ *  A special case for IPv6 is the in6_setscope() routine. ip6_output()
+ *  will not accept an ifp; it wants an embedded scope ID, unlike
+ *  ip_output(), which happily takes the ifp given to it. The embedded
+ *  scope ID is only used by MLD to select the outgoing interface.
+ *
+ *  During interface attach and detach, MLD will take MLD_LOCK *after*
+ *  the IF_AFDATA_LOCK.
+ *  As in6_setscope() takes IF_AFDATA_LOCK then SCOPE_LOCK, we can't call
+ *  it with MLD_LOCK held without triggering an LOR. A netisr with indirect
+ *  dispatch could work around this, but we'd rather not do that, as it
+ *  can introduce other races.
+ *
+ *  As such, we exploit the fact that the scope ID is just the interface
+ *  index, and embed it in the IPv6 destination address accordingly.
+ *  This is potentially NOT VALID for MLDv1 reports, as they
+ *  are always sent to the multicast group itself; as MLDv2
+ *  reports are always sent to ff02::16, this is not an issue
+ *  when MLDv2 is in use.
+ *
+ *  This does not however eliminate the LOR when ip6_output() itself
+ *  calls in6_setscope() internally whilst MLD_LOCK is held. This will
+ *  trigger a LOR warning in WITNESS when the ifnet is detached.
+ *
+ *  The right answer is probably to make IF_AFDATA_LOCK an rwlock, given
+ *  how it's used across the network stack. Here we're simply exploiting
+ *  the fact that MLD runs at a similar layer in the stack to scope6.c.
+ *
+ * VIMAGE:
+ *  * Each in6_multi corresponds to an ifp, and each ifp corresponds
+ *    to a vnet in ifp->if_vnet.
  */
+static struct mtx		 mld_mtx;
+MALLOC_DEFINE(M_MLD, "mld", "mld state");
+
+#define	MLD_EMBEDSCOPE(pin6, zoneid) \
+	(pin6)->s6_addr16[1] = htons((zoneid) & 0xFFFF)
 
-/* denotes that the MLD max response delay field specifies time in milliseconds */
-#define MLD_TIMER_SCALE	1000
 /*
- * time between repetitions of a node's initial report of interest in a
- * multicast address(in seconds)
+ * VIMAGE-wide globals.
  */
-#define MLD_UNSOLICITED_REPORT_INTERVAL	10
-
 #ifdef VIMAGE_GLOBALS
-static struct ip6_pktopts ip6_opts;
-#endif
+struct timeval			 mld_gsrdelay;
+LIST_HEAD(, mld_ifinfo)		 mli_head;
+int				 interface_timers_running6;
+int				 state_change_timers_running6;
+int				 current_state_timers_running6;
+#endif /* VIMAGE_GLOBALS */
 
-static void mld6_sendpkt(struct in6_multi *, int, const struct in6_addr *);
-static void mld_starttimer(struct in6_multi *);
-static void mld_stoptimer(struct in6_multi *);
-static void mld_timeo(struct in6_multi *);
-static u_long mld_timerresid(struct in6_multi *);
+SYSCTL_DECL(_net_inet6);	/* Note: Not in any common header. */
 
-void
-mld6_init(void)
+SYSCTL_NODE(_net_inet6, OID_AUTO, mld, CTLFLAG_RW, 0,
+    "IPv6 Multicast Listener Discovery");
+
+/*
+ * Virtualized sysctls.
+ */
+SYSCTL_V_PROC(V_NET, vnet_inet6, _net_inet6_mld, OID_AUTO, gsrdelay,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, mld_gsrdelay.tv_sec, 0,
+    sysctl_mld_gsr, "I",
+    "Rate limit for MLDv2 Group-and-Source queries in seconds");
+
+/*
+ * Non-virtualized sysctls.
+ */
+SYSCTL_NODE(_net_inet6_mld, OID_AUTO, ifinfo, CTLFLAG_RD | CTLFLAG_MPSAFE,
+    sysctl_mld_ifinfo, "Per-interface MLDv2 state");
+
+/*
+ * Packed Router Alert option structure declaration.
+ */
+struct mld_raopt {
+	struct ip6_hbh		hbh;
+	struct ip6_opt		pad;
+	struct ip6_opt_router	ra;
+} __packed;
+
+/*
+ * Router Alert hop-by-hop option header.
+ */
+static struct mld_raopt mld_ra = {
+	.hbh = { 0, 0 },
+	.pad = { .ip6o_type = IP6OPT_PADN, 0 },
+	.ra = {
+	    .ip6or_type = IP6OPT_ROUTER_ALERT,
+	    .ip6or_len = IP6OPT_RTALERT_LEN - 2,
+	    .ip6or_value[0] = ((IP6OPT_RTALERT_MLD >> 8) & 0xFF),
+	    .ip6or_value[1] = (IP6OPT_RTALERT_MLD & 0xFF)
+	}
+};
+static struct ip6_pktopts mld_po;
+
+static __inline void
+mld_save_context(struct mbuf *m, struct ifnet *ifp)
+{
+
+#ifdef VIMAGE
+	m->m_pkthdr.header = ifp->if_vnet;
+#endif /* VIMAGE */
+	m->m_pkthdr.flowid = ifp->if_index;
+}
+
+static __inline void
+mld_scrub_context(struct mbuf *m)
+{
+
+	m->m_pkthdr.header = NULL;
+	m->m_pkthdr.flowid = 0;
+}
+
+/*
+ * Restore context from a queued output chain.
+ * Return saved ifindex.
+ *
+ * VIMAGE: The assertion is there to make sure that we
+ * actually called CURVNET_SET() with what's in the mbuf chain.
+ */
+static __inline uint32_t
+mld_restore_context(struct mbuf *m)
+{
+
+#ifdef notyet
+#if defined(VIMAGE) && defined(INVARIANTS)
+	KASSERT(curvnet == (m->m_pkthdr.header),
+	    ("%s: called when curvnet was not restored", __func__));
+#endif
+#endif
+	return (m->m_pkthdr.flowid);
+}
+
+/*
+ * Retrieve or set threshold between group-source queries in seconds.
+ *
+ * VIMAGE: Assume curvnet set by caller.
+ * SMPng: NOTE: Serialized by MLD lock.
+ */
+static int
+sysctl_mld_gsr(SYSCTL_HANDLER_ARGS)
 {
 	INIT_VNET_INET6(curvnet);
-	static u_int8_t hbh_buf[8];
-	struct ip6_hbh *hbh = (struct ip6_hbh *)hbh_buf;
-	u_int16_t rtalert_code = htons((u_int16_t)IP6OPT_RTALERT_MLD);
+	int error;
+	int i;
+
+	error = sysctl_wire_old_buffer(req, sizeof(int));
+	if (error)
+		return (error);
 
-	/* ip6h_nxt will be fill in later */
-	hbh->ip6h_len = 0;	/* (8 >> 3) - 1 */
+	MLD_LOCK();
 
-	/* XXX: grotty hard coding... */
-	hbh_buf[2] = IP6OPT_PADN;	/* 2 byte padding */
-	hbh_buf[3] = 0;
-	hbh_buf[4] = IP6OPT_ROUTER_ALERT;
-	hbh_buf[5] = IP6OPT_RTALERT_LEN - 2;
-	bcopy((caddr_t)&rtalert_code, &hbh_buf[6], sizeof(u_int16_t));
+	i = V_mld_gsrdelay.tv_sec;
 
-	ip6_initpktopts(&V_ip6_opts);
-	V_ip6_opts.ip6po_hbh = hbh;
+	error = sysctl_handle_int(oidp, &i, 0, req);
+	if (error || !req->newptr)
+		goto out_locked;
+
+	if (i < -1 || i >= 60) {
+		error = EINVAL;
+		goto out_locked;
+	}
+
+	CTR2(KTR_MLD, "change mld_gsrdelay from %d to %d",
+	     V_mld_gsrdelay.tv_sec, i);
+	V_mld_gsrdelay.tv_sec = i;
+
+out_locked:
+	MLD_UNLOCK();
+	return (error);
 }
 
-static void
-mld_starttimer(struct in6_multi *in6m)
+/*
+ * Expose struct mld_ifinfo to userland, keyed by ifindex.
+ * For use by ifmcstat(8).
+ *
+ * SMPng: NOTE: Does an unlocked ifindex space read.
+ * VIMAGE: Assume curvnet set by caller. The node handler itself
+ * is not directly virtualized.
+ */
+static int
+sysctl_mld_ifinfo(SYSCTL_HANDLER_ARGS)
 {
-	struct timeval now;
+	INIT_VNET_NET(curvnet);
+	INIT_VNET_INET6(curvnet);
+	int			*name;
+	int			 error;
+	u_int			 namelen;
+	struct ifnet		*ifp;
+	struct mld_ifinfo	*mli;
+
+	name = (int *)arg1;
+	namelen = arg2;
+
+	if (req->newptr != NULL)
+		return (EPERM);
 
-	microtime(&now);
-	in6m->in6m_timer_expire.tv_sec = now.tv_sec + in6m->in6m_timer / hz;
-	in6m->in6m_timer_expire.tv_usec = now.tv_usec +
-	    (in6m->in6m_timer % hz) * (1000000 / hz);
-	if (in6m->in6m_timer_expire.tv_usec > 1000000) {
-		in6m->in6m_timer_expire.tv_sec++;
-		in6m->in6m_timer_expire.tv_usec -= 1000000;
+	if (namelen != 1)
+		return (EINVAL);
+
+	error = sysctl_wire_old_buffer(req, sizeof(struct mld_ifinfo));
+	if (error)
+		return (error);
+
+	IN6_MULTI_LOCK();
+	MLD_LOCK();
+
+	if (name[0] <= 0 || name[0] > V_if_index) {
+		error = ENOENT;
+		goto out_locked;
 	}
 
-	/* start or restart the timer */
-	callout_reset(in6m->in6m_timer_ch, in6m->in6m_timer,
-	    (void (*)(void *))mld_timeo, in6m);
+	error = ENOENT;
+
+	ifp = ifnet_byindex(name[0]);
+	if (ifp == NULL)
+		goto out_locked;
+
+	LIST_FOREACH(mli, &V_mli_head, mli_link) {
+		if (ifp == mli->mli_ifp) {
+			error = SYSCTL_OUT(req, mli,
+			    sizeof(struct mld_ifinfo));
+			break;
+		}
+	}
+
+out_locked:
+	MLD_UNLOCK();
+	IN6_MULTI_UNLOCK();
+	return (error);
 }
 
+/*
+ * Dispatch an entire queue of pending packet chains.
+ * VIMAGE: Assumes the vnet pointer has been set.
+ */
 static void
-mld_stoptimer(struct in6_multi *in6m)
+mld_dispatch_queue(struct ifqueue *ifq, int limit)
 {
-	if (in6m->in6m_timer == IN6M_TIMER_UNDEF)
-		return;
+	struct mbuf *m;
 
-	callout_stop(in6m->in6m_timer_ch);
-	in6m->in6m_timer = IN6M_TIMER_UNDEF;
+	for (;;) {
+		_IF_DEQUEUE(ifq, m);
+		if (m == NULL)
+			break;
+		CTR3(KTR_MLD, "%s: dispatch %p from %p", __func__, ifq, m);
+		mld_dispatch_packet(m);
+		if (--limit == 0)
+			break;
+	}
 }
 
-static void
-mld_timeo(struct in6_multi *in6m)
+/*
+ * Filter outgoing MLD report state by group.
+ *
+ * Reports are ALWAYS suppressed for ALL-HOSTS (ff02::1)
+ * and node-local addresses. However, kernel and socket consumers
+ * always embed the KAME scope ID in the address provided, so strip it
+ * when performing comparison.
+ * Note: This is not the same as the *multicast* scope.
+ *
+ * Return zero if the given group is one for which MLD reports
+ * should be suppressed, or non-zero if reports should be issued.
+ */
+static __inline int
+mld_is_addr_reported(const struct in6_addr *addr)
 {
-	int s = splnet();
+	INIT_VNET_INET6(curvnet);
 
-	in6m->in6m_timer = IN6M_TIMER_UNDEF;
+	KASSERT(IN6_IS_ADDR_MULTICAST(addr), ("%s: not multicast", __func__));
 
-	callout_stop(in6m->in6m_timer_ch);
+	if (IPV6_ADDR_MC_SCOPE(addr) == IPV6_ADDR_SCOPE_NODELOCAL)
+		return (0);
 
-	switch (in6m->in6m_state) {
-	case MLD_REPORTPENDING:
-		mld6_start_listening(in6m);
-		break;
-	default:
-		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
-		break;
+	if (IPV6_ADDR_MC_SCOPE(addr) == IPV6_ADDR_SCOPE_LINKLOCAL) {
+		struct in6_addr tmp = *addr;
+		in6_clearscope(&tmp);
+		if (IN6_ARE_ADDR_EQUAL(&tmp, &in6addr_linklocal_allnodes))
+			return (0);
 	}
 
-	splx(s);
+	return (1);
 }
 
-static u_long
-mld_timerresid(struct in6_multi *in6m)
+/*
+ * Attach MLD when PF_INET6 is attached to an interface.
+ *
+ * SMPng: Normally called with IF_AFDATA_LOCK held.
+ * VIMAGE: Currently we set the vnet pointer, although it is
+ * likely that it was already set by our caller.
+ */
+struct mld_ifinfo *
+mld_domifattach(struct ifnet *ifp)
 {
-	struct timeval now, diff;
+	struct mld_ifinfo *mli;
 
-	microtime(&now);
+	CTR3(KTR_MLD, "%s: called for ifp %p(%s)",
+	    __func__, ifp, ifp->if_xname);
 
-	if (now.tv_sec > in6m->in6m_timer_expire.tv_sec ||
-	    (now.tv_sec == in6m->in6m_timer_expire.tv_sec &&
-	    now.tv_usec > in6m->in6m_timer_expire.tv_usec)) {
-		return (0);
-	}
-	diff = in6m->in6m_timer_expire;
-	diff.tv_sec -= now.tv_sec;
-	diff.tv_usec -= now.tv_usec;
-	if (diff.tv_usec < 0) {
-		diff.tv_sec--;
-		diff.tv_usec += 1000000;
-	}
+	CURVNET_SET(ifp->if_vnet);
+	MLD_LOCK();
+
+	mli = mli_alloc_locked(ifp);
+	if (!(ifp->if_flags & IFF_MULTICAST))
+		mli->mli_flags |= MLIF_SILENT;
+
+	MLD_UNLOCK();
+	CURVNET_RESTORE();
 
-	/* return the remaining time in milliseconds */
-	return (diff.tv_sec * 1000 + diff.tv_usec / 1000);
+	return (mli);
 }
 
-void
-mld6_start_listening(struct in6_multi *in6m)
+/*
+ * VIMAGE: assume curvnet set by caller.
+ */
+static struct mld_ifinfo *
+mli_alloc_locked(/*const*/ struct ifnet *ifp)
 {
-	struct in6_addr all_in6;
-	int s = splnet();
+	INIT_VNET_INET6(ifp->if_vnet);
+	struct mld_ifinfo *mli;
+
+	MLD_LOCK_ASSERT();
+
+	mli = malloc(sizeof(struct mld_ifinfo), M_MLD, M_NOWAIT|M_ZERO);
+	if (mli == NULL)
+		goto out;
+
+	mli->mli_ifp = ifp;
+	mli->mli_version = MLD_VERSION_2;
+	mli->mli_flags = 0;
+	mli->mli_rv = MLD_RV_INIT;
+	mli->mli_qi = MLD_QI_INIT;
+	mli->mli_qri = MLD_QRI_INIT;
+	mli->mli_uri = MLD_URI_INIT;
+
+	SLIST_INIT(&mli->mli_relinmhead);
 
 	/*
-	 * RFC2710 page 10:
-	 * The node never sends a Report or Done for the link-scope all-nodes
-	 * address.
-	 * MLD messages are never sent for multicast addresses whose scope is 0
-	 * (reserved) or 1 (node-local).
+	 * Responses to general queries are subject to bounds.
 	 */
-	all_in6 = in6addr_linklocal_allnodes;
-	if (in6_setscope(&all_in6, in6m->in6m_ifp, NULL)) {
-		/* XXX: this should not happen! */
-		in6m->in6m_timer = 0;
-		in6m->in6m_state = MLD_OTHERLISTENER;
-	}
-	if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
-	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
-	    IPV6_ADDR_SCOPE_LINKLOCAL) {
-		in6m->in6m_timer = 0;
-		in6m->in6m_state = MLD_OTHERLISTENER;
-	} else {
-		mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
-		in6m->in6m_timer = arc4random() %
-			MLD_UNSOLICITED_REPORT_INTERVAL * hz;
-		in6m->in6m_state = MLD_IREPORTEDLAST;
+	IFQ_SET_MAXLEN(&mli->mli_gq, MLD_MAX_RESPONSE_PACKETS);
+
+	LIST_INSERT_HEAD(&V_mli_head, mli, mli_link);
+
+	CTR2(KTR_MLD, "allocate mld_ifinfo for ifp %p(%s)",
+	     ifp, ifp->if_xname);
+
+out:
+	return (mli);
+}
+
+/*
+ * Hook for ifdetach.
+ *
+ * NOTE: Some finalization tasks need to run before the protocol domain
+ * is detached, but also before the link layer does its cleanup.
+ * Run before link-layer cleanup; cleanup groups, but do not free MLD state.
+ *
+ * SMPng: Caller must hold IN6_MULTI_LOCK().
+ * Must take IF_ADDR_LOCK() to cover if_multiaddrs iterator.
+ * XXX This routine is also bitten by unlocked ifma_protospec access.
+ *
+ * VIMAGE: curvnet should have been set by caller, but let's not assume
+ * that for now.
+ */
+void
+mld_ifdetach(struct ifnet *ifp)
+{
+	struct mld_ifinfo	*mli;
+	struct ifmultiaddr	*ifma;
+	struct in6_multi	*inm, *tinm;
+
+	CTR3(KTR_MLD, "%s: called for ifp %p(%s)", __func__, ifp,
+	    ifp->if_xname);
+
+	CURVNET_SET(ifp->if_vnet);
 
-		mld_starttimer(in6m);
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK();
+
+	mli = MLD_IFINFO(ifp);
+	if (mli->mli_version == MLD_VERSION_2) {
+		IF_ADDR_LOCK(ifp);
+		TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
+			if (ifma->ifma_addr->sa_family != AF_INET6 ||
+			    ifma->ifma_protospec == NULL)
+				continue;
+			inm = (struct in6_multi *)ifma->ifma_protospec;
+			if (inm->in6m_state == MLD_LEAVING_MEMBER) {
+				SLIST_INSERT_HEAD(&mli->mli_relinmhead,
+				    inm, in6m_nrele);
+			}
+			in6m_clear_recorded(inm);
+		}
+		IF_ADDR_UNLOCK(ifp);
+		SLIST_FOREACH_SAFE(inm, &mli->mli_relinmhead, in6m_nrele,
+		    tinm) {
+			SLIST_REMOVE_HEAD(&mli->mli_relinmhead, in6m_nrele);
+			in6m_release_locked(inm);
+		}
 	}
-	splx(s);
+
+	MLD_UNLOCK();
+	CURVNET_RESTORE();
 }
 
+/*
+ * Hook for domifdetach.
+ * Runs after link-layer cleanup; free MLD state.
+ *
+ * SMPng: Normally called with IF_AFDATA_LOCK held.
+ * VIMAGE: curvnet should have been set by caller, but let's not assume
+ * that for now.
+ */
 void
-mld6_stop_listening(struct in6_multi *in6m)
+mld_domifdetach(struct ifnet *ifp)
 {
-	struct in6_addr allnode, allrouter;
 
-	allnode = in6addr_linklocal_allnodes;
-	if (in6_setscope(&allnode, in6m->in6m_ifp, NULL)) {
-		/* XXX: this should not happen! */
-		return;
+	CTR3(KTR_MLD, "%s: called for ifp %p(%s)",
+	    __func__, ifp, ifp->if_xname);
+
+	CURVNET_SET(ifp->if_vnet);
+
+	MLD_LOCK();
+	mli_delete_locked(ifp);
+	MLD_UNLOCK();
+
+	CURVNET_RESTORE();
+}
+
+static void
+mli_delete_locked(const struct ifnet *ifp)
+{
+	INIT_VNET_INET6(ifp->if_vnet);
+	struct mld_ifinfo *mli, *tmli;
+
+	CTR3(KTR_MLD, "%s: freeing mld_ifinfo for ifp %p(%s)",
+	    __func__, ifp, ifp->if_xname);
+
+	MLD_LOCK_ASSERT();
+
+	LIST_FOREACH_SAFE(mli, &V_mli_head, mli_link, tmli) {
+		if (mli->mli_ifp == ifp) {
+			/*
+			 * Free deferred General Query responses.
+			 */
+			_IF_DRAIN(&mli->mli_gq);
+
+			LIST_REMOVE(mli, mli_link);
+
+			KASSERT(SLIST_EMPTY(&mli->mli_relinmhead),
+			    ("%s: there are dangling in_multi references",
+			    __func__));
+
+			free(mli, M_MLD);
+			return;
+		}
 	}
-	allrouter = in6addr_linklocal_allrouters;
-	if (in6_setscope(&allrouter, in6m->in6m_ifp, NULL)) {
-		/* XXX impossible */
-		return;
+#ifdef INVARIANTS
+	panic("%s: mld_ifinfo not found for ifp %p\n", __func__,  ifp);
+#endif
+}
+
+/*
+ * Process a received MLDv1 general or address-specific query.
+ * Assumes that the query header has been pulled up to sizeof(mld_hdr).
+ */
+static int
+mld_v1_input_query(struct ifnet *ifp, const struct ip6_hdr *ip6,
+    const struct mld_hdr *mld)
+{
+	INIT_VNET_INET6(ifp->if_vnet);
+	struct ifmultiaddr	*ifma;
+	struct mld_ifinfo	*mli;
+	struct in6_multi	*inm;
+	uint16_t		 timer;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	IN6_MULTI_LOCK();
+	IF_ADDR_LOCK(ifp);
+	MLD_LOCK();
+
+	mli = MLD_IFINFO(ifp);
+	KASSERT(mli != NULL, ("%s: no mld_ifinfo for ifp %p", __func__, ifp));
+
+	/*
+	 * Switch to MLDv1 host compatibility mode.
+	 */
+	mld_set_version(mli, MLD_VERSION_1);
+
+	timer = ntohs(mld->mld_maxdelay) * PR_FASTHZ / MLD_TIMER_SCALE;
+	if (timer == 0)
+		timer = 1;
+
+	if (!IN6_IS_ADDR_UNSPECIFIED(&mld->mld_addr)) {
+		/*
+		 * MLDv1 Group-Specific Query.
+		 * If this is a group-specific MLDv1 query, we need only
+		 * look up the single group to process it.
+		 */
+		inm = in6m_lookup_locked(ifp, &mld->mld_addr);
+		if (inm != NULL) {
+			CTR3(KTR_MLD, "process v1 query %s on ifp %p(%s)",
+			    ip6_sprintf(ip6tbuf, &mld->mld_addr),
+			    ifp, ifp->if_xname);
+			mld_v1_update_group(inm, timer);
+		}
+	} else {
+		/*
+		 * MLDv1 General Query.
+		 * If this was not sent to the all-nodes group, ignore it.
+		 *
+		 * XXX Do we need to check for a scope ID in the destination
+		 * address on input and strip it?
+		 */
+		if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
+		    &in6addr_linklocal_allnodes)) {
+			/*
+			 * For each reporting group joined on this
+			 * interface, kick the report timer.
+			 */
+			CTR2(KTR_MLD,
+			    "process v1 general query on ifp %p(%s)",
+			    ifp, ifp->if_xname);
+
+			TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
+				if (ifma->ifma_addr->sa_family != AF_INET6 ||
+				    ifma->ifma_protospec == NULL)
+					continue;
+				inm = (struct in6_multi *)ifma->ifma_protospec;
+				mld_v1_update_group(inm, timer);
+			}
+		}
 	}
-	if (in6m->in6m_state == MLD_IREPORTEDLAST &&
-	    !IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &allnode) &&
-	    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) >
-	    IPV6_ADDR_SCOPE_INTFACELOCAL) {
-		mld6_sendpkt(in6m, MLD_LISTENER_DONE, &allrouter);
+
+	MLD_UNLOCK();
+	IF_ADDR_UNLOCK(ifp);
+	IN6_MULTI_UNLOCK();
+
+	return (0);
+}
+
+/*
+ * Update the report timer on a group in response to an MLDv1 query.
+ *
+ * If we are becoming the reporting member for this group, start the timer.
+ * If we already are the reporting member for this group, and timer is
+ * below the threshold, reset it.
+ *
+ * We may be updating the group for the first time since we switched
+ * to MLDv2. If we are, then we must clear any recorded source lists,
+ * and transition to REPORTING state; the group timer is overloaded
+ * for group and group-source query responses. 
+ *
+ * Unlike MLDv2, the delay per group should be jittered
+ * to avoid bursts of MLDv1 reports.
+ */
+static void
+mld_v1_update_group(struct in6_multi *inm, const int timer)
+{
+	INIT_VNET_INET6(curvnet);
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	CTR4(KTR_MLD, "%s: %s/%s timer=%d", __func__,
+	    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+	    inm->in6m_ifp->if_xname, timer);
+
+	IN6_MULTI_LOCK_ASSERT();
+
+	switch (inm->in6m_state) {
+	case MLD_NOT_MEMBER:
+	case MLD_SILENT_MEMBER:
+		break;
+	case MLD_REPORTING_MEMBER:
+		if (inm->in6m_timer != 0 &&
+		    inm->in6m_timer <= timer) {
+			CTR1(KTR_MLD, "%s: REPORTING and timer running, "
+			    "skipping.", __func__);
+			break;
+		}
+		/* FALLTHROUGH */
+	case MLD_SG_QUERY_PENDING_MEMBER:
+	case MLD_G_QUERY_PENDING_MEMBER:
+	case MLD_IDLE_MEMBER:
+	case MLD_LAZY_MEMBER:
+	case MLD_AWAKENING_MEMBER:
+		CTR1(KTR_MLD, "%s: ->REPORTING", __func__);
+		inm->in6m_state = MLD_REPORTING_MEMBER;
+		inm->in6m_timer = MLD_RANDOM_DELAY(timer);
+		V_current_state_timers_running6 = 1;
+		break;
+	case MLD_SLEEPING_MEMBER:
+		CTR1(KTR_MLD, "%s: ->AWAKENING", __func__);
+		inm->in6m_state = MLD_AWAKENING_MEMBER;
+		break;
+	case MLD_LEAVING_MEMBER:
+		break;
 	}
 }
 
-void
-mld6_input(struct mbuf *m, int off)
+/*
+ * Process a received MLDv2 general, group-specific or
+ * group-and-source-specific query.
+ *
+ * Assumes that the query header has been pulled up to sizeof(mldv2_query).
+ *
+ * Return 0 if successful, otherwise an appropriate error code is returned.
+ */
+static int
+mld_v2_input_query(struct ifnet *ifp, const struct ip6_hdr *ip6,
+    struct mbuf *m, const int off, const int icmp6len)
 {
 	INIT_VNET_INET6(curvnet);
-	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
-	struct mld_hdr *mldh;
-	struct ifnet *ifp = m->m_pkthdr.rcvif;
-	struct in6_multi *in6m;
-	struct in6_addr mld_addr, all_in6;
-	struct in6_ifaddr *ia;
-	struct ifmultiaddr *ifma;
-	u_long timer;		/* timer value in the MLD query header */
-
-#ifndef PULLDOWN_TEST
-	IP6_EXTHDR_CHECK(m, off, sizeof(*mldh),);
-	mldh = (struct mld_hdr *)(mtod(m, caddr_t) + off);
-#else
-	IP6_EXTHDR_GET(mldh, struct mld_hdr *, m, off, sizeof(*mldh));
-	if (mldh == NULL) {
-		ICMP6STAT_INC(icp6s_tooshort);
-		return;
+	struct mld_ifinfo	*mli;
+	struct mldv2_query	*mld;
+	struct in6_multi	*inm;
+	uint32_t		 maxdelay, nsrc, qqi;
+	uint16_t		 timer;
+	uint8_t			 qrv;
+
+	CTR2(KTR_MLD, "process v2 query on ifp %p(%s)", ifp, ifp->if_xname);
+
+	mld = (struct mldv2_query *)(mtod(m, uint8_t *) + off);
+
+	maxdelay = ntohs(mld->mld_maxdelay);	/* in 1/10ths of a second */
+	if (maxdelay >= 32678) {
+		maxdelay = (MLD_MRC_MANT(mld->mld_maxdelay) | 0x1000) <<
+			   (MLD_MRC_EXP(mld->mld_maxdelay) + 3);
 	}
-#endif
 
-	/* source address validation */
-	ip6 = mtod(m, struct ip6_hdr *); /* in case mpullup */
-	if (!IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src)) {
-		char ip6bufs[INET6_ADDRSTRLEN], ip6bufg[INET6_ADDRSTRLEN];
-		log(LOG_ERR,
-		    "mld6_input: src %s is not link-local (grp=%s)\n",
-		    ip6_sprintf(ip6bufs, &ip6->ip6_src),
-		    ip6_sprintf(ip6bufg, &mldh->mld_addr));
+	qrv = MLD_QRV(mld->mld_misc);
+	if (qrv < 2) {
+		CTR3(KTR_MLD, "%s: clamping qrv %d to %d", __func__,
+		    qrv, MLD_RV_INIT);
+		qrv = MLD_RV_INIT;
+	}
+
+	qqi = mld->mld_qqi;
+	if (qqi >= 128) {
+		qqi = MLD_QQIC_MANT(mld->mld_qqi) <<
+		     (MLD_QQIC_EXP(mld->mld_qqi) + 3);
+	}
+
+	timer = maxdelay * PR_FASTHZ / MLD_TIMER_SCALE;
+	if (timer == 0)
+		timer = 1;
+
+	nsrc = ntohs(mld->mld_numsrc);
+	if (nsrc > MLD_MAX_GS_SOURCES)
+		return (EMSGSIZE);
+	if (icmp6len < sizeof(struct mldv2_query) +
+	    (nsrc * sizeof(struct in6_addr)))
+		return (EMSGSIZE);
+
+	IN6_MULTI_LOCK();
+	IF_ADDR_LOCK(ifp);
+	MLD_LOCK();
+
+	mli = MLD_IFINFO(ifp);
+	KASSERT(mli != NULL, ("%s: no mld_ifinfo for ifp %p", __func__, ifp));
+
+	mld_set_version(mli, MLD_VERSION_2);
+
+	mli->mli_rv = qrv;
+	mli->mli_qi = qqi;
+	mli->mli_qri = maxdelay;
+
+	CTR4(KTR_MLD, "%s: qrv %d qi %d qri %d", __func__, qrv, qqi,
+	    maxdelay);
+
+	if (IN6_IS_ADDR_UNSPECIFIED(&mld->mld_addr)) {
 		/*
-		 * spec (RFC2710) does not explicitly
-		 * specify to discard the packet from a non link-local
-		 * source address. But we believe it's expected to do so.
-		 * XXX: do we have to allow :: as source?
+		 * MLDv2 General Query.
+		 * Schedule a current-state report on this ifp for
+		 * all groups, possibly containing source lists.
 		 */
-		m_freem(m);
-		return;
+		if (!IN6_ARE_ADDR_EQUAL(&in6addr_linklocal_allnodes,
+		    &ip6->ip6_dst) || nsrc > 0) {
+			/*
+			 * General Queries SHOULD be directed to ff02::1.
+			 * A general query with a source list has undefined
+			 * behaviour; discard it.
+			 */
+			goto out_locked;
+		}
+
+		CTR2(KTR_MLD, "process v2 general query on ifp %p(%s)",
+		    ifp, ifp->if_xname);
+
+		/*
+		 * If there is a pending General Query response
+		 * scheduled earlier than the selected delay, do
+		 * not schedule any other reports.
+		 * Otherwise, reset the interface timer.
+		 */
+		if (mli->mli_v1_timer == 0 || mli->mli_v2_timer >= timer) {
+			mli->mli_v1_timer = MLD_RANDOM_DELAY(timer);
+			V_interface_timers_running6 = 1;
+		}
+	} else {
+		/*
+		 * MLDv2 Group-specific or Group-and-source-specific Query.
+		 *
+		 * Group-source-specific queries are throttled on
+		 * a per-group basis to defeat denial-of-service attempts.
+		 * Queries for groups we are not a member of on this
+		 * link are simply ignored.
+		 */
+		inm = in6m_lookup_locked(ifp, &mld->mld_addr);
+		if (inm == NULL)
+			goto out_locked;
+		if (nsrc > 0) {
+			if (!ratecheck(&inm->in6m_lastgsrtv,
+			    &V_mld_gsrdelay)) {
+				CTR1(KTR_MLD, "%s: GS query throttled.",
+				    __func__);
+				goto out_locked;
+			}
+		}
+		CTR2(KTR_MLD, "process v2 group query on ifp %p(%s)",
+		     ifp, ifp->if_xname);
+		/*
+		 * If there is a pending General Query response
+		 * scheduled sooner than the selected delay, no
+		 * further report need be scheduled.
+		 * Otherwise, prepare to respond to the
+		 * group-specific or group-and-source query.
+		 */
+		if (mli->mli_v1_timer == 0 || mli->mli_v2_timer >= timer)
+			mld_v2_process_group_query(inm, mli, timer, m, off);
+	}
+
+out_locked:
+	MLD_UNLOCK();
+	IF_ADDR_UNLOCK(ifp);
+	IN6_MULTI_UNLOCK();
+
+	return (0);
+}
+
+/*
+ * Process a recieved MLDv2 group-specific or group-and-source-specific
+ * query.
+ * Return <0 if any error occured. Currently this is ignored.
+ */
+static int
+mld_v2_process_group_query(struct in6_multi *inm, struct mld_ifinfo *mli,
+    int timer, struct mbuf *m0, const int off)
+{
+	INIT_VNET_INET6(curvnet);
+	struct mldv2_query	*mld;
+	int			 retval;
+	uint16_t		 nsrc;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	retval = 0;
+	mld = (struct mldv2_query *)(mtod(m0, uint8_t *) + off);
+
+	switch (inm->in6m_state) {
+	case MLD_NOT_MEMBER:
+	case MLD_SILENT_MEMBER:
+	case MLD_SLEEPING_MEMBER:
+	case MLD_LAZY_MEMBER:
+	case MLD_AWAKENING_MEMBER:
+	case MLD_IDLE_MEMBER:
+	case MLD_LEAVING_MEMBER:
+		return (retval);
+		break;
+	case MLD_REPORTING_MEMBER:
+	case MLD_G_QUERY_PENDING_MEMBER:
+	case MLD_SG_QUERY_PENDING_MEMBER:
+		break;
 	}
 
+	nsrc = ntohs(mld->mld_numsrc);
+
 	/*
-	 * make a copy for local work (in6_setscope() may modify the 1st arg)
+	 * Deal with group-specific queries upfront.
+	 * If any group query is already pending, purge any recorded
+	 * source-list state if it exists, and schedule a query response
+	 * for this group-specific query.
 	 */
-	mld_addr = mldh->mld_addr;
-	if (in6_setscope(&mld_addr, ifp, NULL)) {
-		/* XXX: this should not happen! */
-		m_free(m);
-		return;
+	if (nsrc == 0) {
+		if (inm->in6m_state == MLD_G_QUERY_PENDING_MEMBER ||
+		    inm->in6m_state == MLD_SG_QUERY_PENDING_MEMBER) {
+			in6m_clear_recorded(inm);
+			timer = min(inm->in6m_timer, timer);
+		}
+		inm->in6m_state = MLD_G_QUERY_PENDING_MEMBER;
+		inm->in6m_timer = MLD_RANDOM_DELAY(timer);
+		V_current_state_timers_running6 = 1;
+		return (retval);
 	}
 
 	/*
-	 * In the MLD6 specification, there are 3 states and a flag.
-	 *
-	 * In Non-Listener state, we simply don't have a membership record.
-	 * In Delaying Listener state, our timer is running (in6m->in6m_timer)
-	 * In Idle Listener state, our timer is not running
-	 * (in6m->in6m_timer==IN6M_TIMER_UNDEF)
-	 *
-	 * The flag is in6m->in6m_state, it is set to MLD_OTHERLISTENER if
-	 * we have heard a report from another member, or MLD_IREPORTEDLAST
-	 * if we sent the last report.
+	 * Deal with the case where a group-and-source-specific query has
+	 * been received but a group-specific query is already pending.
 	 */
-	switch(mldh->mld_type) {
-	case MLD_LISTENER_QUERY:
-		if (ifp->if_flags & IFF_LOOPBACK)
-			break;
-
-		if (!IN6_IS_ADDR_UNSPECIFIED(&mld_addr) &&
-		    !IN6_IS_ADDR_MULTICAST(&mld_addr))
-			break;	/* print error or log stat? */
+	if (inm->in6m_state == MLD_G_QUERY_PENDING_MEMBER) {
+		timer = min(inm->in6m_timer, timer);
+		inm->in6m_timer = MLD_RANDOM_DELAY(timer);
+		V_current_state_timers_running6 = 1;
+		return (retval);
+	}
 
-		all_in6 = in6addr_linklocal_allnodes;
-		if (in6_setscope(&all_in6, ifp, NULL)) {
-			/* XXX: this should not happen! */
-			break;
+	/*
+	 * Finally, deal with the case where a group-and-source-specific
+	 * query has been received, where a response to a previous g-s-r
+	 * query exists, or none exists.
+	 * In this case, we need to parse the source-list which the Querier
+	 * has provided us with and check if we have any source list filter
+	 * entries at T1 for these sources. If we do not, there is no need
+	 * schedule a report and the query may be dropped.
+	 * If we do, we must record them and schedule a current-state
+	 * report for those sources.
+	 */
+	if (inm->in6m_nsrc > 0) {
+		struct mbuf		*m;
+		uint8_t			*sp;
+		int			 i, nrecorded;
+		int			 soff;
+
+		m = m0;
+		soff = off + sizeof(struct mldv2_query);
+		nrecorded = 0;
+		for (i = 0; i < nsrc; i++) {
+			sp = mtod(m, uint8_t *) + soff;
+			retval = in6m_record_source(inm,
+			    (const struct in6_addr *)sp);
+			if (retval < 0)
+				break;
+			nrecorded += retval;
+			soff += sizeof(struct in6_addr);
+			if (soff >= m->m_len) {
+				soff = soff - m->m_len;
+				m = m->m_next;
+				if (m == NULL)
+					break;
+			}
+		}
+		if (nrecorded > 0) {
+			CTR1(KTR_MLD,
+			    "%s: schedule response to SG query", __func__);
+			inm->in6m_state = MLD_SG_QUERY_PENDING_MEMBER;
+			inm->in6m_timer = MLD_RANDOM_DELAY(timer);
+			V_current_state_timers_running6 = 1;
 		}
+	}
+
+	return (retval);
+}
+
+/*
+ * Process a received MLDv1 host membership report.
+ * Assumes mld points to mld_hdr in pulled up mbuf chain.
+ */
+static int
+mld_v1_input_report(struct ifnet *ifp, const struct ip6_hdr *ip6,
+    const struct mld_hdr *mld)
+{
+	INIT_VNET_INET6(curvnet);
+	struct in6_ifaddr	*ia;
+	struct in6_multi	*inm;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	if (ifp->if_flags & IFF_LOOPBACK)
+		return (0);
+
+	if (!IN6_IS_ADDR_MULTICAST(&mld->mld_addr) ||
+	    !IN6_ARE_ADDR_EQUAL(&mld->mld_addr, &ip6->ip6_dst))
+		return (EINVAL);
+
+	/*
+	 * Make sure we don't hear our own membership report, as fast
+	 * leave requires knowing that we are the only member of a
+	 * group. Assume we used the link-local address if available,
+	 * otherwise look for ::.
+	 */
+	ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
+	if ((ia && IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, IA6_IN6(ia))) ||
+	    (ia == NULL && IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)))
+		return (0);
+
+	CTR3(KTR_MLD, "process v1 report %s on ifp %p(%s)",
+	    ip6_sprintf(ip6tbuf, &mld->mld_addr), ifp, ifp->if_xname);
+
+	IN6_MULTI_LOCK();
+	IF_ADDR_LOCK(ifp);
+
+	/*
+	 * MLDv1 report suppression.
+	 * If we are a member of this group, and our membership should be
+	 * reported, and our group timer is pending or about to be reset,
+	 * stop our group timer by transitioning to the 'lazy' state.
+	 */
+	inm = in6m_lookup_locked(ifp, &mld->mld_addr);
+	if (inm != NULL) {
+		struct mld_ifinfo *mli;
+
+		mli = inm->in6m_mli;
+		KASSERT(mli != NULL,
+		    ("%s: no mli for ifp %p", __func__, ifp));
 
 		/*
-		 * - Start the timers in all of our membership records
-		 *   that the query applies to for the interface on
-		 *   which the query arrived excl. those that belong
-		 *   to the "all-nodes" group (ff02::1).
-		 * - Restart any timer that is already running but has
-		 *   A value longer than the requested timeout.
-		 * - Use the value specified in the query message as
-		 *   the maximum timeout.
+		 * If we are in MLDv2 host mode, do not allow the
+		 * other host's MLDv1 report to suppress our reports.
 		 */
-		timer = ntohs(mldh->mld_maxdelay);
+		if (mli->mli_version == MLD_VERSION_2)
+			goto out_locked;
 
-		IF_ADDR_LOCK(ifp);
-		IFP_TO_IA6(ifp, ia);
-		if (ia == NULL) {
-			IF_ADDR_UNLOCK(ifp);
+		inm->in6m_timer = 0;
+
+		switch (inm->in6m_state) {
+		case MLD_NOT_MEMBER:
+		case MLD_SILENT_MEMBER:
+		case MLD_SLEEPING_MEMBER:
+			break;
+		case MLD_REPORTING_MEMBER:
+		case MLD_IDLE_MEMBER:
+		case MLD_AWAKENING_MEMBER:
+			CTR3(KTR_MLD,
+			    "report suppressed for %s on ifp %p(%s)",
+			    ip6_sprintf(ip6tbuf, &mld->mld_addr),
+			    ifp, ifp->if_xname);
+		case MLD_LAZY_MEMBER:
+			inm->in6m_state = MLD_LAZY_MEMBER;
+			break;
+		case MLD_G_QUERY_PENDING_MEMBER:
+		case MLD_SG_QUERY_PENDING_MEMBER:
+		case MLD_LEAVING_MEMBER:
 			break;
 		}
+	}
 
-		/*
-		 * XXX: System timer resolution is too low to handle Max
-		 * Response Delay, so set 1 to the internal timer even if
-		 * the calculated value equals to zero when Max Response
-		 * Delay is positive.
-		 */
-		timer = ntohs(mldh->mld_maxdelay) * PR_FASTHZ / MLD_TIMER_SCALE;
-		if (timer == 0 && mldh->mld_maxdelay)
-			timer = 1;
+out_locked:
+	IF_ADDR_UNLOCK(ifp);
+	IN6_MULTI_UNLOCK();
 
-		TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
-			if (ifma->ifma_addr->sa_family != AF_INET6)
-				continue;
-			in6m = (struct in6_multi *)ifma->ifma_protospec;
+	return (0);
+}
 
-			if (IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_in6) ||
-			    IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) <
-			    IPV6_ADDR_SCOPE_LINKLOCAL)
-				continue;
+/*
+ * MLD input path.
+ *
+ * Assume query messages which fit in a single ICMPv6 message header
+ * have been pulled up.
+ * Assume that userland will want to see the message, even if it
+ * otherwise fails kernel input validation; do not free it.
+ * Pullup may however free the mbuf chain m if it fails.
+ *
+ * Return IPPROTO_DONE if we freed m. Otherwise, return 0.
+ */
+int
+mld_input(struct mbuf *m, int off, int icmp6len)
+{
+	struct ifnet	*ifp;
+	struct ip6_hdr	*ip6;
+	struct mld_hdr	*mld;
+	int		 mldlen;
 
-			if (IN6_IS_ADDR_UNSPECIFIED(&mld_addr) ||
-			    IN6_ARE_ADDR_EQUAL(&mld_addr, &in6m->in6m_addr)) {
-				if (timer == 0) {
-					/* send a report immediately */
-					mld_stoptimer(in6m);
-					mld6_sendpkt(in6m, MLD_LISTENER_REPORT,
-						NULL);
-					in6m->in6m_timer = 0; /* reset timer */
-					in6m->in6m_state = MLD_IREPORTEDLAST;
-				}
-				else if (in6m->in6m_timer == IN6M_TIMER_UNDEF ||
-				    mld_timerresid(in6m) > timer) {
-					in6m->in6m_timer =
-					   1 + (arc4random() % timer) * hz / 1000;
-					mld_starttimer(in6m);
-				}
+	CTR3(KTR_MLD, "%s: called w/mbuf (%p,%d)", __func__, m, off);
+
+	ifp = m->m_pkthdr.rcvif;
+	INIT_VNET_INET6(ifp->if_vnet);
+
+	ip6 = mtod(m, struct ip6_hdr *);
+
+	/* Pullup to appropriate size. */
+	mld = (struct mld_hdr *)(mtod(m, uint8_t *) + off);
+	if (mld->mld_type == MLD_LISTENER_QUERY &&
+	    icmp6len >= sizeof(struct mldv2_query)) {
+		mldlen = sizeof(struct mldv2_query);
+	} else {
+		mldlen = sizeof(struct mld_hdr);
+	}
+	IP6_EXTHDR_GET(mld, struct mld_hdr *, m, off, mldlen);
+	if (mld == NULL) {
+		ICMP6STAT_INC(icp6s_badlen);
+		return (IPPROTO_DONE);
+	}
+
+	switch (mld->mld_type) {
+	case MLD_LISTENER_QUERY:
+		icmp6_ifstat_inc(ifp, ifs6_in_mldquery);
+		if (icmp6len == sizeof(struct mld_hdr)) {
+			if (mld_v1_input_query(ifp, ip6, mld) != 0)
+				return (0);
+		} else if (icmp6len >= sizeof(struct mldv2_query)) {
+			if (mld_v2_input_query(ifp, ip6, m, off,
+			    icmp6len) != 0)
+				return (0);
+		}
+		break;
+	case MLD_LISTENER_REPORT:
+		icmp6_ifstat_inc(ifp, ifs6_in_mldreport);
+		if (mld_v1_input_report(ifp, ip6, mld) != 0)
+			return (0);	/* Userland needs to see it. */
+		break;
+	case MLDV2_LISTENER_REPORT:
+		icmp6_ifstat_inc(ifp, ifs6_in_mldreport);
+		break;
+	case MLD_LISTENER_DONE:
+		icmp6_ifstat_inc(ifp, ifs6_in_mlddone);
+		break;
+	default:
+		break;
+	}
+
+	return (0);
+}
+
+/*
+ * Fast timeout handler (global).
+ * VIMAGE: Timeout handlers are expected to service all vimages.
+ */
+void
+mld_fasttimo(void)
+{
+	VNET_ITERATOR_DECL(vnet_iter);
+
+	VNET_LIST_RLOCK();
+	VNET_FOREACH(vnet_iter) {
+		CURVNET_SET(vnet_iter);
+		mld_fasttimo_vnet();
+		CURVNET_RESTORE();
+	}
+	VNET_LIST_RUNLOCK();
+}
+
+/*
+ * Fast timeout handler (per-vnet).
+ *
+ * VIMAGE: Assume caller has set up our curvnet.
+ */
+static void
+mld_fasttimo_vnet(void)
+{
+	INIT_VNET_INET6(curvnet);
+	struct ifqueue		 scq;	/* State-change packets */
+	struct ifqueue		 qrq;	/* Query response packets */
+	struct ifnet		*ifp;
+	struct mld_ifinfo	*mli;
+	struct ifmultiaddr	*ifma, *tifma;
+	struct in6_multi	*inm;
+	int			 uri_fasthz;
+
+	uri_fasthz = 0;
+
+	/*
+	 * Quick check to see if any work needs to be done, in order to
+	 * minimize the overhead of fasttimo processing.
+	 * SMPng: XXX Unlocked reads.
+	 */
+	if (!V_current_state_timers_running6 &&
+	    !V_interface_timers_running6 &&
+	    !V_state_change_timers_running6)
+		return;
+
+	IN6_MULTI_LOCK();
+	MLD_LOCK();
+
+	/*
+	 * MLDv2 General Query response timer processing.
+	 */
+	if (V_interface_timers_running6) {
+		CTR1(KTR_MLD, "%s: interface timers running", __func__);
+
+		V_interface_timers_running6 = 0;
+		LIST_FOREACH(mli, &V_mli_head, mli_link) {
+			if (mli->mli_v2_timer == 0) {
+				/* Do nothing. */
+			} else if (--mli->mli_v2_timer == 0) {
+				mld_v2_dispatch_general_query(mli);
+			} else {
+				V_interface_timers_running6 = 1;
+			}
+		}
+	}
+
+	if (!V_current_state_timers_running6 &&
+	    !V_state_change_timers_running6)
+		goto out_locked;
+
+	V_current_state_timers_running6 = 0;
+	V_state_change_timers_running6 = 0;
+
+	CTR1(KTR_MLD, "%s: state change timers running", __func__);
+
+	/*
+	 * MLD host report and state-change timer processing.
+	 * Note: Processing a v2 group timer may remove a node.
+	 */
+	LIST_FOREACH(mli, &V_mli_head, mli_link) {
+		ifp = mli->mli_ifp;
+
+		if (mli->mli_version == MLD_VERSION_2) {
+			uri_fasthz = MLD_RANDOM_DELAY(mli->mli_uri *
+			    PR_FASTHZ);
+
+			memset(&qrq, 0, sizeof(struct ifqueue));
+			IFQ_SET_MAXLEN(&qrq, MLD_MAX_G_GS_PACKETS);
+
+			memset(&scq, 0, sizeof(struct ifqueue));
+			IFQ_SET_MAXLEN(&scq, MLD_MAX_STATE_CHANGE_PACKETS);
+		}
+
+		IF_ADDR_LOCK(ifp);
+		TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link,
+		    tifma) {
+			if (ifma->ifma_addr->sa_family != AF_INET6 ||
+			    ifma->ifma_protospec == NULL)
+				continue;
+			inm = (struct in6_multi *)ifma->ifma_protospec;
+			switch (mli->mli_version) {
+			case MLD_VERSION_1:
+				mld_v1_process_group_timer(inm,
+				    mli->mli_version);
+				break;
+			case MLD_VERSION_2:
+				mld_v2_process_group_timers(mli, &qrq,
+				    &scq, inm, uri_fasthz);
+				break;
 			}
 		}
 		IF_ADDR_UNLOCK(ifp);
+
+		if (mli->mli_version == MLD_VERSION_2) {
+			struct in6_multi		*tinm;
+
+			mld_dispatch_queue(&qrq, 0);
+			mld_dispatch_queue(&scq, 0);
+
+			/*
+			 * Free the in_multi reference(s) for
+			 * this lifecycle.
+			 */
+			SLIST_FOREACH_SAFE(inm, &mli->mli_relinmhead,
+			    in6m_nrele, tinm) {
+				SLIST_REMOVE_HEAD(&mli->mli_relinmhead,
+				    in6m_nrele);
+				in6m_release_locked(inm);
+			}
+		}
+	}
+
+out_locked:
+	MLD_UNLOCK();
+	IN6_MULTI_UNLOCK();
+}
+
+/*
+ * Update host report group timer.
+ * Will update the global pending timer flags.
+ */
+static void
+mld_v1_process_group_timer(struct in6_multi *inm, const int version)
+{
+	INIT_VNET_INET6(curvnet);
+	int report_timer_expired;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	if (inm->in6m_timer == 0) {
+		report_timer_expired = 0;
+	} else if (--inm->in6m_timer == 0) {
+		report_timer_expired = 1;
+	} else {
+		V_current_state_timers_running6 = 1;
+		return;
+	}
+
+	switch (inm->in6m_state) {
+	case MLD_NOT_MEMBER:
+	case MLD_SILENT_MEMBER:
+	case MLD_IDLE_MEMBER:
+	case MLD_LAZY_MEMBER:
+	case MLD_SLEEPING_MEMBER:
+	case MLD_AWAKENING_MEMBER:
+		break;
+	case MLD_REPORTING_MEMBER:
+		if (report_timer_expired) {
+			inm->in6m_state = MLD_IDLE_MEMBER;
+			(void)mld_v1_transmit_report(inm,
+			     MLD_LISTENER_REPORT);
+		}
+		break;
+	case MLD_G_QUERY_PENDING_MEMBER:
+	case MLD_SG_QUERY_PENDING_MEMBER:
+	case MLD_LEAVING_MEMBER:
 		break;
+	}
+}
 
-	case MLD_LISTENER_REPORT:
+/*
+ * Update a group's timers for MLDv2.
+ * Will update the global pending timer flags.
+ * Note: Unlocked read from mli.
+ */
+static void
+mld_v2_process_group_timers(struct mld_ifinfo *mli,
+    struct ifqueue *qrq, struct ifqueue *scq,
+    struct in6_multi *inm, const int uri_fasthz)
+{
+	INIT_VNET_INET6(curvnet);
+	int query_response_timer_expired;
+	int state_change_retransmit_timer_expired;
+#ifdef KTR
+	char ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	query_response_timer_expired = 0;
+	state_change_retransmit_timer_expired = 0;
+
+	/*
+	 * During a transition from compatibility mode back to MLDv2,
+	 * a group record in REPORTING state may still have its group
+	 * timer active. This is a no-op in this function; it is easier
+	 * to deal with it here than to complicate the slow-timeout path.
+	 */
+	if (inm->in6m_timer == 0) {
+		query_response_timer_expired = 0;
+	} else if (--inm->in6m_timer == 0) {
+		query_response_timer_expired = 1;
+	} else {
+		V_current_state_timers_running6 = 1;
+	}
+
+	if (inm->in6m_sctimer == 0) {
+		state_change_retransmit_timer_expired = 0;
+	} else if (--inm->in6m_sctimer == 0) {
+		state_change_retransmit_timer_expired = 1;
+	} else {
+		V_state_change_timers_running6 = 1;
+	}
+
+	/* We are in fasttimo, so be quick about it. */
+	if (!state_change_retransmit_timer_expired &&
+	    !query_response_timer_expired)
+		return;
+
+	switch (inm->in6m_state) {
+	case MLD_NOT_MEMBER:
+	case MLD_SILENT_MEMBER:
+	case MLD_SLEEPING_MEMBER:
+	case MLD_LAZY_MEMBER:
+	case MLD_AWAKENING_MEMBER:
+	case MLD_IDLE_MEMBER:
+		break;
+	case MLD_G_QUERY_PENDING_MEMBER:
+	case MLD_SG_QUERY_PENDING_MEMBER:
 		/*
-		 * For fast leave to work, we have to know that we are the
-		 * last person to send a report for this group.  Reports
-		 * can potentially get looped back if we are a multicast
-		 * router, so discard reports sourced by me.
-		 * Note that it is impossible to check IFF_LOOPBACK flag of
-		 * ifp for this purpose, since ip6_mloopback pass the physical
-		 * interface to looutput.
+		 * Respond to a previously pending Group-Specific
+		 * or Group-and-Source-Specific query by enqueueing
+		 * the appropriate Current-State report for
+		 * immediate transmission.
 		 */
-		if (m->m_flags & M_LOOP) /* XXX: grotty flag, but efficient */
-			break;
+		if (query_response_timer_expired) {
+			int retval;
+
+			retval = mld_v2_enqueue_group_record(qrq, inm, 0, 1,
+			    (inm->in6m_state == MLD_SG_QUERY_PENDING_MEMBER));
+			CTR2(KTR_MLD, "%s: enqueue record = %d",
+			    __func__, retval);
+			inm->in6m_state = MLD_REPORTING_MEMBER;
+			in6m_clear_recorded(inm);
+		}
+		/* FALLTHROUGH */
+	case MLD_REPORTING_MEMBER:
+	case MLD_LEAVING_MEMBER:
+		if (state_change_retransmit_timer_expired) {
+			/*
+			 * State-change retransmission timer fired.
+			 * If there are any further pending retransmissions,
+			 * set the global pending state-change flag, and
+			 * reset the timer.
+			 */
+			if (--inm->in6m_scrv > 0) {
+				inm->in6m_sctimer = uri_fasthz;
+				V_state_change_timers_running6 = 1;
+			}
+			/*
+			 * Retransmit the previously computed state-change
+			 * report. If there are no further pending
+			 * retransmissions, the mbuf queue will be consumed.
+			 * Update T0 state to T1 as we have now sent
+			 * a state-change.
+			 */
+			(void)mld_v2_merge_state_changes(inm, scq);
+
+			in6m_commit(inm);
+			CTR3(KTR_MLD, "%s: T1 -> T0 for %s/%s", __func__,
+			    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+			    inm->in6m_ifp->if_xname);
+
+			/*
+			 * If we are leaving the group for good, make sure
+			 * we release MLD's reference to it.
+			 * This release must be deferred using a SLIST,
+			 * as we are called from a loop which traverses
+			 * the in_ifmultiaddr TAILQ.
+			 */
+			if (inm->in6m_state == MLD_LEAVING_MEMBER &&
+			    inm->in6m_scrv == 0) {
+				inm->in6m_state = MLD_NOT_MEMBER;
+				SLIST_INSERT_HEAD(&mli->mli_relinmhead,
+				    inm, in6m_nrele);
+			}
+		}
+		break;
+	}
+}
 
-		if (!IN6_IS_ADDR_MULTICAST(&mld_addr))
-			break;
+/*
+ * Switch to a different version on the given interface,
+ * as per Section 9.12.
+ */
+static void
+mld_set_version(struct mld_ifinfo *mli, const int version)
+{
 
+	MLD_LOCK_ASSERT();
+
+	CTR4(KTR_MLD, "%s: switching to v%d on ifp %p(%s)", __func__,
+	    version, mli->mli_ifp, mli->mli_ifp->if_xname);
+
+	if (version == MLD_VERSION_1) {
+		int old_version_timer;
 		/*
-		 * If we belong to the group being reported, stop
-		 * our timer for that group.
+		 * Compute the "Older Version Querier Present" timer as per
+		 * Section 9.12.
 		 */
-		IN6_LOOKUP_MULTI(mld_addr, ifp, in6m);
-		if (in6m) {
-			in6m->in6m_timer = 0; /* transit to idle state */
-			in6m->in6m_state = MLD_OTHERLISTENER; /* clear flag */
+		old_version_timer = mli->mli_rv * mli->mli_qi + mli->mli_qri;
+		old_version_timer *= PR_SLOWHZ;
+
+		if (version == MLD_VERSION_1) {
+			mli->mli_v1_timer = old_version_timer;
 		}
-		break;
-	default:		/* this is impossible */
-		log(LOG_ERR, "mld6_input: illegal type(%d)", mldh->mld_type);
-		break;
 	}
 
-	m_freem(m);
+	if (mli->mli_v1_timer > 0) {
+		if (mli->mli_version != MLD_VERSION_1) {
+			mli->mli_version = MLD_VERSION_1;
+			mld_v2_cancel_link_timers(mli);
+		}
+	}
 }
 
+/*
+ * Cancel pending MLDv2 timers for the given link and all groups
+ * joined on it; state-change, general-query, and group-query timers.
+ */
 static void
-mld6_sendpkt(struct in6_multi *in6m, int type, const struct in6_addr *dst)
+mld_v2_cancel_link_timers(struct mld_ifinfo *mli)
 {
 	INIT_VNET_INET6(curvnet);
-	struct mbuf *mh, *md;
-	struct mld_hdr *mldh;
-	struct ip6_hdr *ip6;
-	struct ip6_moptions im6o;
-	struct in6_ifaddr *ia;
-	struct ifnet *ifp = in6m->in6m_ifp;
-	struct ifnet *outif = NULL;
+	struct ifmultiaddr	*ifma;
+	struct ifnet		*ifp;
+	struct in6_multi		*inm;
+
+	CTR3(KTR_MLD, "%s: cancel v2 timers on ifp %p(%s)", __func__,
+	    mli->mli_ifp, mli->mli_ifp->if_xname);
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
 
 	/*
-	 * At first, find a link local address on the outgoing interface
-	 * to use as the source address of the MLD packet.
+	 * Fast-track this potentially expensive operation
+	 * by checking all the global 'timer pending' flags.
 	 */
-	if ((ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST))
-	    == NULL)
+	if (!V_interface_timers_running6 &&
+	    !V_state_change_timers_running6 &&
+	    !V_current_state_timers_running6)
 		return;
 
-	/*
-	 * Allocate mbufs to store ip6 header and MLD header.
-	 * We allocate 2 mbufs and make chain in advance because
-	 * it is more convenient when inserting the hop-by-hop option later.
-	 */
+	mli->mli_v2_timer = 0;
+
+	ifp = mli->mli_ifp;
+
+	IF_ADDR_LOCK(ifp);
+	TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
+		if (ifma->ifma_addr->sa_family != AF_INET6)
+			continue;
+		inm = (struct in6_multi *)ifma->ifma_protospec;
+		switch (inm->in6m_state) {
+		case MLD_NOT_MEMBER:
+		case MLD_SILENT_MEMBER:
+		case MLD_IDLE_MEMBER:
+		case MLD_LAZY_MEMBER:
+		case MLD_SLEEPING_MEMBER:
+		case MLD_AWAKENING_MEMBER:
+			break;
+		case MLD_LEAVING_MEMBER:
+			/*
+			 * If we are leaving the group and switching
+			 * version, we need to release the final
+			 * reference held for issuing the INCLUDE {}.
+			 *
+			 * SMPNG: Must drop and re-acquire IF_ADDR_LOCK
+			 * around in6m_release_locked(), as it is not
+			 * a recursive mutex.
+			 */
+			IF_ADDR_UNLOCK(ifp);
+			in6m_release_locked(inm);
+			IF_ADDR_LOCK(ifp);
+			/* FALLTHROUGH */
+		case MLD_G_QUERY_PENDING_MEMBER:
+		case MLD_SG_QUERY_PENDING_MEMBER:
+			in6m_clear_recorded(inm);
+			/* FALLTHROUGH */
+		case MLD_REPORTING_MEMBER:
+			inm->in6m_sctimer = 0;
+			inm->in6m_timer = 0;
+			inm->in6m_state = MLD_REPORTING_MEMBER;
+			/*
+			 * Free any pending MLDv2 state-change records.
+			 */
+			_IF_DRAIN(&inm->in6m_scq);
+			break;
+		}
+	}
+	IF_ADDR_UNLOCK(ifp);
+}
+
+/*
+ * Global slowtimo handler.
+ * VIMAGE: Timeout handlers are expected to service all vimages.
+ */
+void
+mld_slowtimo(void)
+{
+	VNET_ITERATOR_DECL(vnet_iter);
+
+	VNET_LIST_RLOCK();
+	VNET_FOREACH(vnet_iter) {
+		CURVNET_SET(vnet_iter);
+		mld_slowtimo_vnet();
+		CURVNET_RESTORE();
+	}
+	VNET_LIST_RUNLOCK();
+}
+
+/*
+ * Per-vnet slowtimo handler.
+ */
+static void
+mld_slowtimo_vnet(void)
+{
+	INIT_VNET_INET6(curvnet);
+	struct mld_ifinfo *mli;
+
+	MLD_LOCK();
+
+	LIST_FOREACH(mli, &V_mli_head, mli_link) {
+		mld_v1_process_querier_timers(mli);
+	}
+
+	MLD_UNLOCK();
+}
+
+/*
+ * Update the Older Version Querier Present timers for a link.
+ * See Section 9.12 of RFC 3810.
+ */
+static void
+mld_v1_process_querier_timers(struct mld_ifinfo *mli)
+{
+	INIT_VNET_INET6(curvnet);
+
+	MLD_LOCK_ASSERT();
+
+	if (mli->mli_v1_timer == 0) {
+		/*
+		 * MLDv1 Querier Present timers expired; revert to MLDv2.
+		 */
+		if (mli->mli_version != MLD_VERSION_2) {
+			CTR5(KTR_MLD,
+			    "%s: transition from v%d -> v%d on %p(%s)",
+			    __func__, mli->mli_version, MLD_VERSION_2,
+			    mli->mli_ifp, mli->mli_ifp->if_xname);
+			mli->mli_version = MLD_VERSION_2;
+		}
+	}
+}
+
+/*
+ * Transmit an MLDv1 report immediately.
+ */
+static int
+mld_v1_transmit_report(struct in6_multi *in6m, const int type)
+{
+	struct ifnet		*ifp;
+	struct in6_ifaddr	*ia;
+	struct ip6_hdr		*ip6;
+	struct mbuf		*mh, *md;
+	struct mld_hdr		*mld;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	ifp = in6m->in6m_ifp;
+	ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
+	/* ia may be NULL if link-local address is tentative. */
+
 	MGETHDR(mh, M_DONTWAIT, MT_HEADER);
 	if (mh == NULL)
-		return;
+		return (ENOMEM);
 	MGET(md, M_DONTWAIT, MT_DATA);
 	if (md == NULL) {
 		m_free(mh);
-		return;
+		return (ENOMEM);
 	}
 	mh->m_next = md;
 
-	mh->m_pkthdr.rcvif = NULL;
+	/*
+	 * FUTURE: Consider increasing alignment by ETHER_HDR_LEN, so
+	 * that ether_output() does not need to allocate another mbuf
+	 * for the header in the most common case.
+	 */
+	MH_ALIGN(mh, sizeof(struct ip6_hdr));
 	mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
 	mh->m_len = sizeof(struct ip6_hdr);
-	MH_ALIGN(mh, sizeof(struct ip6_hdr));
 
-	/* fill in the ip6 header */
 	ip6 = mtod(mh, struct ip6_hdr *);
 	ip6->ip6_flow = 0;
 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
 	ip6->ip6_vfc |= IPV6_VERSION;
-	/* ip6_plen will be set later */
 	ip6->ip6_nxt = IPPROTO_ICMPV6;
-	/* ip6_hlim will be set by im6o.im6o_multicast_hlim */
-	ip6->ip6_src = ia->ia_addr.sin6_addr;
-	ip6->ip6_dst = dst ? *dst : in6m->in6m_addr;
+	ip6->ip6_src = ia ? ia->ia_addr.sin6_addr : in6addr_any;
+	ip6->ip6_dst = in6m->in6m_addr;
 
-	/* fill in the MLD header */
 	md->m_len = sizeof(struct mld_hdr);
-	mldh = mtod(md, struct mld_hdr *);
-	mldh->mld_type = type;
-	mldh->mld_code = 0;
-	mldh->mld_cksum = 0;
-	/* XXX: we assume the function will not be called for query messages */
-	mldh->mld_maxdelay = 0;
-	mldh->mld_reserved = 0;
-	mldh->mld_addr = in6m->in6m_addr;
-	in6_clearscope(&mldh->mld_addr); /* XXX */
-	mldh->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6, sizeof(struct ip6_hdr),
-				    sizeof(struct mld_hdr));
-
-	/* construct multicast option */
-	bzero(&im6o, sizeof(im6o));
-	im6o.im6o_multicast_ifp = ifp;
-	im6o.im6o_multicast_hlim = 1;
+	mld = mtod(md, struct mld_hdr *);
+	mld->mld_type = type;
+	mld->mld_code = 0;
+	mld->mld_cksum = 0;
+	mld->mld_maxdelay = 0;
+	mld->mld_reserved = 0;
+	mld->mld_addr = in6m->in6m_addr;
+	in6_clearscope(&mld->mld_addr);
+	mld->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6,
+	    sizeof(struct ip6_hdr), sizeof(struct mld_hdr));
+
+	mld_save_context(mh, ifp);
+	mh->m_flags |= M_MLDV1;
+
+	mld_dispatch_packet(mh);
+
+	return (0);
+}
+
+/*
+ * Process a state change from the upper layer for the given IPv6 group.
+ *
+ * Each socket holds a reference on the in_multi in its own ip_moptions.
+ * The socket layer will have made the necessary updates to.the group
+ * state, it is now up to MLD to issue a state change report if there
+ * has been any change between T0 (when the last state-change was issued)
+ * and T1 (now).
+ *
+ * We use the MLDv2 state machine at group level. The MLd module
+ * however makes the decision as to which MLD protocol version to speak.
+ * A state change *from* INCLUDE {} always means an initial join.
+ * A state change *to* INCLUDE {} always means a final leave.
+ *
+ * If delay is non-zero, and the state change is an initial multicast
+ * join, the state change report will be delayed by 'delay' ticks
+ * in units of PR_FASTHZ if MLDv1 is active on the link; otherwise
+ * the initial MLDv2 state change report will be delayed by whichever
+ * is sooner, a pending state-change timer or delay itself.
+ *
+ * VIMAGE: curvnet should have been set by caller, as this routine
+ * is called from the socket option handlers.
+ */
+int
+mld_change_state(struct in6_multi *inm, const int delay)
+{
+	struct mld_ifinfo *mli;
+	struct ifnet *ifp;
+	int error;
+
+	IN6_MULTI_LOCK_ASSERT();
+
+	error = 0;
 
 	/*
-	 * Request loopback of the report if we are acting as a multicast
-	 * router, so that the process-level routing daemon can hear it.
+	 * Try to detect if the upper layer just asked us to change state
+	 * for an interface which has now gone away.
 	 */
-	im6o.im6o_multicast_loop = (ip6_mrouter != NULL);
+	KASSERT(inm->in6m_ifma != NULL, ("%s: no ifma", __func__));
+	ifp = inm->in6m_ifma->ifma_ifp;
+	if (ifp != NULL) {
+		/*
+		 * Sanity check that netinet6's notion of ifp is the
+		 * same as net's.
+		 */
+		KASSERT(inm->in6m_ifp == ifp, ("%s: bad ifp", __func__));
+	}
 
-	/* increment output statictics */
-	ICMP6STAT_INC(icp6s_outhist[type]);
+	MLD_LOCK();
 
-	ip6_output(mh, &V_ip6_opts, NULL, 0, &im6o, &outif, NULL);
-	if (outif) {
-		icmp6_ifstat_inc(outif, ifs6_out_msg);
-		switch (type) {
-		case MLD_LISTENER_QUERY:
-			icmp6_ifstat_inc(outif, ifs6_out_mldquery);
+	mli = MLD_IFINFO(ifp);
+	KASSERT(mli != NULL, ("%s: no mld_ifinfo for ifp %p", __func__, ifp));
+
+	/*
+	 * If we detect a state transition to or from MCAST_UNDEFINED
+	 * for this group, then we are starting or finishing an MLD
+	 * life cycle for this group.
+	 */
+	if (inm->in6m_st[1].iss_fmode != inm->in6m_st[0].iss_fmode) {
+		CTR3(KTR_MLD, "%s: inm transition %d -> %d", __func__,
+		    inm->in6m_st[0].iss_fmode, inm->in6m_st[1].iss_fmode);
+		if (inm->in6m_st[0].iss_fmode == MCAST_UNDEFINED) {
+			CTR1(KTR_MLD, "%s: initial join", __func__);
+			error = mld_initial_join(inm, mli, delay);
+			goto out_locked;
+		} else if (inm->in6m_st[1].iss_fmode == MCAST_UNDEFINED) {
+			CTR1(KTR_MLD, "%s: final leave", __func__);
+			mld_final_leave(inm, mli);
+			goto out_locked;
+		}
+	} else {
+		CTR1(KTR_MLD, "%s: filter set change", __func__);
+	}
+
+	error = mld_handle_state_change(inm, mli);
+
+out_locked:
+	MLD_UNLOCK();
+	return (error);
+}
+
+/*
+ * Perform the initial join for an MLD group.
+ *
+ * When joining a group:
+ *  If the group should have its MLD traffic suppressed, do nothing.
+ *  MLDv1 starts sending MLDv1 host membership reports.
+ *  MLDv2 will schedule an MLDv2 state-change report containing the
+ *  initial state of the membership.
+ *
+ * If the delay argument is non-zero, then we must delay sending the
+ * initial state change for delay ticks (in units of PR_FASTHZ).
+ */
+static int
+mld_initial_join(struct in6_multi *inm, struct mld_ifinfo *mli,
+    const int delay)
+{
+	INIT_VNET_INET6(curvnet);
+	struct ifnet		*ifp;
+	struct ifqueue		*ifq;
+	int			 error, retval, syncstates;
+	int			 odelay;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	CTR4(KTR_MLD, "%s: initial join %s on ifp %p(%s)",
+	    __func__, ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+	    inm->in6m_ifp, inm->in6m_ifp->if_xname);
+
+	error = 0;
+	syncstates = 1;
+
+	ifp = inm->in6m_ifp;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	KASSERT(mli && mli->mli_ifp == ifp, ("%s: inconsistent ifp", __func__));
+
+	/*
+	 * Groups joined on loopback or marked as 'not reported',
+	 * enter the MLD_SILENT_MEMBER state and
+	 * are never reported in any protocol exchanges.
+	 * All other groups enter the appropriate state machine
+	 * for the version in use on this link.
+	 * A link marked as MLIF_SILENT causes MLD to be completely
+	 * disabled for the link.
+	 */
+	if ((ifp->if_flags & IFF_LOOPBACK) ||
+	    (mli->mli_flags & MLIF_SILENT) ||
+	    !mld_is_addr_reported(&inm->in6m_addr)) {
+		CTR1(KTR_MLD,
+"%s: not kicking state machine for silent group", __func__);
+		inm->in6m_state = MLD_SILENT_MEMBER;
+		inm->in6m_timer = 0;
+	} else {
+		/*
+		 * Deal with overlapping in_multi lifecycle.
+		 * If this group was LEAVING, then make sure
+		 * we drop the reference we picked up to keep the
+		 * group around for the final INCLUDE {} enqueue.
+		 */
+		if (mli->mli_version == MLD_VERSION_2 &&
+		    inm->in6m_state == MLD_LEAVING_MEMBER)
+			in6m_release_locked(inm);
+
+		inm->in6m_state = MLD_REPORTING_MEMBER;
+
+		switch (mli->mli_version) {
+		case MLD_VERSION_1:
+			/*
+			 * If a delay was provided, only use it if
+			 * it is greater than the delay normally
+			 * used for an MLDv1 state change report,
+			 * and delay sending the initial MLDv1 report
+			 * by not transitioning to the IDLE state.
+			 */
+			odelay = MLD_RANDOM_DELAY(MLD_V1_MAX_RI * PR_FASTHZ);
+			if (delay) {
+				inm->in6m_timer = max(delay, odelay);
+				V_current_state_timers_running6 = 1;
+			} else {
+				inm->in6m_state = MLD_IDLE_MEMBER;
+				error = mld_v1_transmit_report(inm,
+				     MLD_LISTENER_REPORT);
+				if (error == 0) {
+					inm->in6m_timer = odelay;
+					V_current_state_timers_running6 = 1;
+				}
+			}
 			break;
-		case MLD_LISTENER_REPORT:
-			icmp6_ifstat_inc(outif, ifs6_out_mldreport);
+
+		case MLD_VERSION_2:
+			/*
+			 * Defer update of T0 to T1, until the first copy
+			 * of the state change has been transmitted.
+			 */
+			syncstates = 0;
+
+			/*
+			 * Immediately enqueue a State-Change Report for
+			 * this interface, freeing any previous reports.
+			 * Don't kick the timers if there is nothing to do,
+			 * or if an error occurred.
+			 */
+			ifq = &inm->in6m_scq;
+			_IF_DRAIN(ifq);
+			retval = mld_v2_enqueue_group_record(ifq, inm, 1,
+			    0, 0);
+			CTR2(KTR_MLD, "%s: enqueue record = %d",
+			    __func__, retval);
+			if (retval <= 0) {
+				error = retval * -1;
+				break;
+			}
+
+			/*
+			 * Schedule transmission of pending state-change
+			 * report up to RV times for this link. The timer
+			 * will fire at the next mld_fasttimo (~200ms),
+			 * giving us an opportunity to merge the reports.
+			 *
+			 * If a delay was provided to this function, only
+			 * use this delay if sooner than the existing one.
+			 */
+			KASSERT(mli->mli_rv > 1,
+			   ("%s: invalid robustness %d", __func__,
+			    mli->mli_rv));
+			inm->in6m_scrv = mli->mli_rv;
+			if (delay) {
+				if (inm->in6m_sctimer > 1) {
+					inm->in6m_sctimer =
+					    min(inm->in6m_sctimer, delay);
+				} else
+					inm->in6m_sctimer = delay;
+			} else
+				inm->in6m_sctimer = 1;
+			V_state_change_timers_running6 = 1;
+
+			error = 0;
 			break;
-		case MLD_LISTENER_DONE:
-			icmp6_ifstat_inc(outif, ifs6_out_mlddone);
+		}
+	}
+
+	/*
+	 * Only update the T0 state if state change is atomic,
+	 * i.e. we don't need to wait for a timer to fire before we
+	 * can consider the state change to have been communicated.
+	 */
+	if (syncstates) {
+		in6m_commit(inm);
+		CTR3(KTR_MLD, "%s: T1 -> T0 for %s/%s", __func__,
+		    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+		    inm->in6m_ifp->if_xname);
+	}
+
+	return (error);
+}
+
+/*
+ * Issue an intermediate state change during the life-cycle.
+ */
+static int
+mld_handle_state_change(struct in6_multi *inm, struct mld_ifinfo *mli)
+{
+	INIT_VNET_INET6(curvnet);
+	struct ifnet		*ifp;
+	int			 retval;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	CTR4(KTR_MLD, "%s: state change for %s on ifp %p(%s)",
+	    __func__, ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+	    inm->in6m_ifp, inm->in6m_ifp->if_xname);
+
+	ifp = inm->in6m_ifp;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	KASSERT(mli && mli->mli_ifp == ifp,
+	    ("%s: inconsistent ifp", __func__));
+
+	if ((ifp->if_flags & IFF_LOOPBACK) ||
+	    (mli->mli_flags & MLIF_SILENT) ||
+	    !mld_is_addr_reported(&inm->in6m_addr) ||
+	    (mli->mli_version != MLD_VERSION_2)) {
+		if (!mld_is_addr_reported(&inm->in6m_addr)) {
+			CTR1(KTR_MLD,
+"%s: not kicking state machine for silent group", __func__);
+		}
+		CTR1(KTR_MLD, "%s: nothing to do", __func__);
+		in6m_commit(inm);
+		CTR3(KTR_MLD, "%s: T1 -> T0 for %s/%s", __func__,
+		    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+		    inm->in6m_ifp->if_xname);
+		return (0);
+	}
+
+	_IF_DRAIN(&inm->in6m_scq);
+
+	retval = mld_v2_enqueue_group_record(&inm->in6m_scq, inm, 1, 0, 0);
+	CTR2(KTR_MLD, "%s: enqueue record = %d", __func__, retval);
+	if (retval <= 0)
+		return (-retval);
+
+	/*
+	 * If record(s) were enqueued, start the state-change
+	 * report timer for this group.
+	 */
+	inm->in6m_scrv = mli->mli_rv;
+	inm->in6m_sctimer = 1;
+	V_state_change_timers_running6 = 1;
+
+	return (0);
+}
+
+/*
+ * Perform the final leave for a multicast address.
+ *
+ * When leaving a group:
+ *  MLDv1 sends a DONE message, if and only if we are the reporter.
+ *  MLDv2 enqueues a state-change report containing a transition
+ *  to INCLUDE {} for immediate transmission.
+ */
+static void
+mld_final_leave(struct in6_multi *inm, struct mld_ifinfo *mli)
+{
+	INIT_VNET_INET6(curvnet);
+	int syncstates;
+#ifdef KTR
+	char ip6tbuf[INET6_ADDRSTRLEN];
+#endif
+
+	syncstates = 1;
+
+	CTR4(KTR_MLD, "%s: final leave %s on ifp %p(%s)",
+	    __func__, ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+	    inm->in6m_ifp, inm->in6m_ifp->if_xname);
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	switch (inm->in6m_state) {
+	case MLD_NOT_MEMBER:
+	case MLD_SILENT_MEMBER:
+	case MLD_LEAVING_MEMBER:
+		/* Already leaving or left; do nothing. */
+		CTR1(KTR_MLD,
+"%s: not kicking state machine for silent group", __func__);
+		break;
+	case MLD_REPORTING_MEMBER:
+	case MLD_IDLE_MEMBER:
+	case MLD_G_QUERY_PENDING_MEMBER:
+	case MLD_SG_QUERY_PENDING_MEMBER:
+		if (mli->mli_version == MLD_VERSION_1) {
+#ifdef INVARIANTS
+			if (inm->in6m_state == MLD_G_QUERY_PENDING_MEMBER ||
+			    inm->in6m_state == MLD_SG_QUERY_PENDING_MEMBER)
+			panic("%s: MLDv2 state reached, not MLDv2 mode",
+			     __func__);
+#endif
+			mld_v1_transmit_report(inm, MLD_LISTENER_DONE);
+			inm->in6m_state = MLD_NOT_MEMBER;
+		} else if (mli->mli_version == MLD_VERSION_2) {
+			/*
+			 * Stop group timer and all pending reports.
+			 * Immediately enqueue a state-change report
+			 * TO_IN {} to be sent on the next fast timeout,
+			 * giving us an opportunity to merge reports.
+			 */
+			_IF_DRAIN(&inm->in6m_scq);
+			inm->in6m_timer = 0;
+			inm->in6m_scrv = mli->mli_rv;
+			CTR4(KTR_MLD, "%s: Leaving %s/%s with %d "
+			    "pending retransmissions.", __func__,
+			    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+			    inm->in6m_ifp->if_xname, inm->in6m_scrv);
+			if (inm->in6m_scrv == 0) {
+				inm->in6m_state = MLD_NOT_MEMBER;
+				inm->in6m_sctimer = 0;
+			} else {
+				int retval;
+
+				in6m_acquire_locked(inm);
+
+				retval = mld_v2_enqueue_group_record(
+				    &inm->in6m_scq, inm, 1, 0, 0);
+				KASSERT(retval != 0,
+				    ("%s: enqueue record = %d", __func__,
+				     retval));
+
+				inm->in6m_state = MLD_LEAVING_MEMBER;
+				inm->in6m_sctimer = 1;
+				V_state_change_timers_running6 = 1;
+				syncstates = 0;
+			}
 			break;
 		}
+		break;
+	case MLD_LAZY_MEMBER:
+	case MLD_SLEEPING_MEMBER:
+	case MLD_AWAKENING_MEMBER:
+		/* Our reports are suppressed; do nothing. */
+		break;
+	}
+
+	if (syncstates) {
+		in6m_commit(inm);
+		CTR3(KTR_MLD, "%s: T1 -> T0 for %s/%s", __func__,
+		    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+		    inm->in6m_ifp->if_xname);
+		inm->in6m_st[1].iss_fmode = MCAST_UNDEFINED;
+		CTR3(KTR_MLD, "%s: T1 now MCAST_UNDEFINED for %p/%s",
+		    __func__, &inm->in6m_addr, inm->in6m_ifp->if_xname);
 	}
 }
 
 /*
- * Add an address to the list of IP6 multicast addresses for a given interface.
- * Add source addresses to the list also, if upstream router is MLDv2 capable
- * and the number of source is not 0.
+ * Enqueue an MLDv2 group record to the given output queue.
+ *
+ * If is_state_change is zero, a current-state record is appended.
+ * If is_state_change is non-zero, a state-change report is appended.
+ *
+ * If is_group_query is non-zero, an mbuf packet chain is allocated.
+ * If is_group_query is zero, and if there is a packet with free space
+ * at the tail of the queue, it will be appended to providing there
+ * is enough free space.
+ * Otherwise a new mbuf packet chain is allocated.
+ *
+ * If is_source_query is non-zero, each source is checked to see if
+ * it was recorded for a Group-Source query, and will be omitted if
+ * it is not both in-mode and recorded.
+ *
+ * The function will attempt to allocate leading space in the packet
+ * for the IPv6+ICMP headers to be prepended without fragmenting the chain.
+ *
+ * If successful the size of all data appended to the queue is returned,
+ * otherwise an error code less than zero is returned, or zero if
+ * no record(s) were appended.
  */
-struct in6_multi *
-in6_addmulti(struct in6_addr *maddr6, struct ifnet *ifp,
-    int *errorp, int delay)
+static int
+mld_v2_enqueue_group_record(struct ifqueue *ifq, struct in6_multi *inm,
+    const int is_state_change, const int is_group_query,
+    const int is_source_query)
 {
-	struct in6_multi *in6m;
+	struct mldv2_record	 mr;
+	struct mldv2_record	*pmr;
+	struct ifnet		*ifp;
+	struct ip6_msource	*ims, *nims;
+	struct mbuf		*m0, *m, *md;
+	int			 error, is_filter_list_change;
+	int			 minrec0len, m0srcs, msrcs, nbytes, off;
+	int			 record_has_sources;
+	int			 now;
+	int			 type;
+	uint8_t			 mode;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
 
-	*errorp = 0;
-	in6m = NULL;
+	IN6_MULTI_LOCK_ASSERT();
+
+	error = 0;
+	ifp = inm->in6m_ifp;
+	is_filter_list_change = 0;
+	m = NULL;
+	m0 = NULL;
+	m0srcs = 0;
+	msrcs = 0;
+	nbytes = 0;
+	nims = NULL;
+	record_has_sources = 1;
+	pmr = NULL;
+	type = MLD_DO_NOTHING;
+	mode = inm->in6m_st[1].iss_fmode;
 
-	/*IN6_MULTI_LOCK();*/
+	/*
+	 * If we did not transition out of ASM mode during t0->t1,
+	 * and there are no source nodes to process, we can skip
+	 * the generation of source records.
+	 */
+	if (inm->in6m_st[0].iss_asm > 0 && inm->in6m_st[1].iss_asm > 0 &&
+	    inm->in6m_nsrc == 0)
+		record_has_sources = 0;
 
-	IN6_LOOKUP_MULTI(*maddr6, ifp, in6m);
-	if (in6m != NULL) {
+	if (is_state_change) {
 		/*
-		 * If we already joined this group, just bump the
-		 * refcount and return it.
+		 * Queue a state change record.
+		 * If the mode did not change, and there are non-ASM
+		 * listeners or source filters present,
+		 * we potentially need to issue two records for the group.
+		 * If we are transitioning to MCAST_UNDEFINED, we need
+		 * not send any sources.
+		 * If there are ASM listeners, and there was no filter
+		 * mode transition of any kind, do nothing.
 		 */
-		KASSERT(in6m->in6m_refcount >= 1,
-		    ("%s: bad refcount %d", __func__, in6m->in6m_refcount));
-		++in6m->in6m_refcount;
-	} else do {
-		struct in6_multi *nin6m;
-		struct ifmultiaddr *ifma;
-		struct sockaddr_in6 sa6;
-
-		bzero(&sa6, sizeof(sa6));
-		sa6.sin6_family = AF_INET6;
-		sa6.sin6_len = sizeof(struct sockaddr_in6);
-		sa6.sin6_addr = *maddr6;
-
-		*errorp = if_addmulti(ifp, (struct sockaddr *)&sa6, &ifma);
-		if (*errorp)
-			break;
+		if (mode != inm->in6m_st[0].iss_fmode) {
+			if (mode == MCAST_EXCLUDE) {
+				CTR1(KTR_MLD, "%s: change to EXCLUDE",
+				    __func__);
+				type = MLD_CHANGE_TO_EXCLUDE_MODE;
+			} else {
+				CTR1(KTR_MLD, "%s: change to INCLUDE",
+				    __func__);
+				type = MLD_CHANGE_TO_INCLUDE_MODE;
+				if (mode == MCAST_UNDEFINED)
+					record_has_sources = 0;
+			}
+		} else {
+			if (record_has_sources) {
+				is_filter_list_change = 1;
+			} else {
+				type = MLD_DO_NOTHING;
+			}
+		}
+	} else {
+		/*
+		 * Queue a current state record.
+		 */
+		if (mode == MCAST_EXCLUDE) {
+			type = MLD_MODE_IS_EXCLUDE;
+		} else if (mode == MCAST_INCLUDE) {
+			type = MLD_MODE_IS_INCLUDE;
+			KASSERT(inm->in6m_st[1].iss_asm == 0,
+			    ("%s: inm %p is INCLUDE but ASM count is %d",
+			     __func__, inm, inm->in6m_st[1].iss_asm));
+		}
+	}
+
+	/*
+	 * Generate the filter list changes using a separate function.
+	 */
+	if (is_filter_list_change)
+		return (mld_v2_enqueue_filter_change(ifq, inm));
+
+	if (type == MLD_DO_NOTHING) {
+		CTR3(KTR_MLD, "%s: nothing to do for %s/%s",
+		    __func__, ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+		    inm->in6m_ifp->if_xname);
+		return (0);
+	}
+
+	/*
+	 * If any sources are present, we must be able to fit at least
+	 * one in the trailing space of the tail packet's mbuf,
+	 * ideally more.
+	 */
+	minrec0len = sizeof(struct mldv2_record);
+	if (record_has_sources)
+		minrec0len += sizeof(struct in6_addr);
+
+	CTR4(KTR_MLD, "%s: queueing %s for %s/%s", __func__,
+	    mld_rec_type_to_str(type),
+	    ip6_sprintf(ip6tbuf, &inm->in6m_addr),
+	    inm->in6m_ifp->if_xname);
+
+	/*
+	 * Check if we have a packet in the tail of the queue for this
+	 * group into which the first group record for this group will fit.
+	 * Otherwise allocate a new packet.
+	 * Always allocate leading space for IP6+RA+ICMPV6+REPORT.
+	 * Note: Group records for G/GSR query responses MUST be sent
+	 * in their own packet.
+	 */
+	m0 = ifq->ifq_tail;
+	if (!is_group_query &&
+	    m0 != NULL &&
+	    (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <= MLD_V2_REPORT_MAXRECS) &&
+	    (m0->m_pkthdr.len + minrec0len) <
+	     (ifp->if_mtu - MLD_MTUSPACE)) {
+		m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
+			    sizeof(struct mldv2_record)) /
+			    sizeof(struct in6_addr);
+		m = m0;
+		CTR1(KTR_MLD, "%s: use existing packet", __func__);
+	} else {
+		if (_IF_QFULL(ifq)) {
+			CTR1(KTR_MLD, "%s: outbound queue full", __func__);
+			return (-ENOMEM);
+		}
+		m = NULL;
+		m0srcs = (ifp->if_mtu - MLD_MTUSPACE -
+		    sizeof(struct mldv2_record)) / sizeof(struct in6_addr);
+		if (!is_state_change && !is_group_query)
+			m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
+		if (m == NULL)
+			m = m_gethdr(M_DONTWAIT, MT_DATA);
+		if (m == NULL)
+			return (-ENOMEM);
+
+		mld_save_context(m, ifp);
+
+		CTR1(KTR_MLD, "%s: allocated first packet", __func__);
+	}
+
+	/*
+	 * Append group record.
+	 * If we have sources, we don't know how many yet.
+	 */
+	mr.mr_type = type;
+	mr.mr_datalen = 0;
+	mr.mr_numsrc = 0;
+	mr.mr_addr = inm->in6m_addr;
+	in6_clearscope(&mr.mr_addr);
+	if (!m_append(m, sizeof(struct mldv2_record), (void *)&mr)) {
+		if (m != m0)
+			m_freem(m);
+		CTR1(KTR_MLD, "%s: m_append() failed.", __func__);
+		return (-ENOMEM);
+	}
+	nbytes += sizeof(struct mldv2_record);
+
+	/*
+	 * Append as many sources as will fit in the first packet.
+	 * If we are appending to a new packet, the chain allocation
+	 * may potentially use clusters; use m_getptr() in this case.
+	 * If we are appending to an existing packet, we need to obtain
+	 * a pointer to the group record after m_append(), in case a new
+	 * mbuf was allocated.
+	 * Only append sources which are in-mode at t1. If we are
+	 * transitioning to MCAST_UNDEFINED state on the group, do not
+	 * include source entries.
+	 * Only report recorded sources in our filter set when responding
+	 * to a group-source query.
+	 */
+	if (record_has_sources) {
+		if (m == m0) {
+			md = m_last(m);
+			pmr = (struct mldv2_record *)(mtod(md, uint8_t *) +
+			    md->m_len - nbytes);
+		} else {
+			md = m_getptr(m, 0, &off);
+			pmr = (struct mldv2_record *)(mtod(md, uint8_t *) +
+			    off);
+		}
+		msrcs = 0;
+		RB_FOREACH_SAFE(ims, ip6_msource_tree, &inm->in6m_srcs,
+		    nims) {
+			CTR2(KTR_MLD, "%s: visit node %s", __func__,
+			    ip6_sprintf(ip6tbuf, &ims->im6s_addr));
+			now = im6s_get_mode(inm, ims, 1);
+			CTR2(KTR_MLD, "%s: node is %d", __func__, now);
+			if ((now != mode) ||
+			    (now == mode && mode == MCAST_UNDEFINED)) {
+				CTR1(KTR_MLD, "%s: skip node", __func__);
+				continue;
+			}
+			if (is_source_query && ims->im6s_stp == 0) {
+				CTR1(KTR_MLD, "%s: skip unrecorded node",
+				    __func__);
+				continue;
+			}
+			CTR1(KTR_MLD, "%s: append node", __func__);
+			if (!m_append(m, sizeof(struct in6_addr),
+			    (void *)&ims->im6s_addr)) {
+				if (m != m0)
+					m_freem(m);
+				CTR1(KTR_MLD, "%s: m_append() failed.",
+				    __func__);
+				return (-ENOMEM);
+			}
+			nbytes += sizeof(struct in6_addr);
+			++msrcs;
+			if (msrcs == m0srcs)
+				break;
+		}
+		CTR2(KTR_MLD, "%s: msrcs is %d this packet", __func__,
+		    msrcs);
+		pmr->mr_numsrc = htons(msrcs);
+		nbytes += (msrcs * sizeof(struct in6_addr));
+	}
+
+	if (is_source_query && msrcs == 0) {
+		CTR1(KTR_MLD, "%s: no recorded sources to report", __func__);
+		if (m != m0)
+			m_freem(m);
+		return (0);
+	}
+
+	/*
+	 * We are good to go with first packet.
+	 */
+	if (m != m0) {
+		CTR1(KTR_MLD, "%s: enqueueing first packet", __func__);
+		m->m_pkthdr.PH_vt.vt_nrecs = 1;
+		_IF_ENQUEUE(ifq, m);
+	} else
+		m->m_pkthdr.PH_vt.vt_nrecs++;
+
+	/*
+	 * No further work needed if no source list in packet(s).
+	 */
+	if (!record_has_sources)
+		return (nbytes);
+
+	/*
+	 * Whilst sources remain to be announced, we need to allocate
+	 * a new packet and fill out as many sources as will fit.
+	 * Always try for a cluster first.
+	 */
+	while (nims != NULL) {
+		if (_IF_QFULL(ifq)) {
+			CTR1(KTR_MLD, "%s: outbound queue full", __func__);
+			return (-ENOMEM);
+		}
+		m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
+		if (m == NULL)
+			m = m_gethdr(M_DONTWAIT, MT_DATA);
+		if (m == NULL)
+			return (-ENOMEM);
+		mld_save_context(m, ifp);
+		md = m_getptr(m, 0, &off);
+		pmr = (struct mldv2_record *)(mtod(md, uint8_t *) + off);
+		CTR1(KTR_MLD, "%s: allocated next packet", __func__);
+
+		if (!m_append(m, sizeof(struct mldv2_record), (void *)&mr)) {
+			if (m != m0)
+				m_freem(m);
+			CTR1(KTR_MLD, "%s: m_append() failed.", __func__);
+			return (-ENOMEM);
+		}
+		m->m_pkthdr.PH_vt.vt_nrecs = 1;
+		nbytes += sizeof(struct mldv2_record);
+
+		m0srcs = (ifp->if_mtu - MLD_MTUSPACE -
+		    sizeof(struct mldv2_record)) / sizeof(struct in6_addr);
+
+		msrcs = 0;
+		RB_FOREACH_FROM(ims, ip6_msource_tree, nims) {
+			CTR2(KTR_MLD, "%s: visit node %s",
+			    __func__, ip6_sprintf(ip6tbuf, &ims->im6s_addr));
+			now = im6s_get_mode(inm, ims, 1);
+			if ((now != mode) ||
+			    (now == mode && mode == MCAST_UNDEFINED)) {
+				CTR1(KTR_MLD, "%s: skip node", __func__);
+				continue;
+			}
+			if (is_source_query && ims->im6s_stp == 0) {
+				CTR1(KTR_MLD, "%s: skip unrecorded node",
+				    __func__);
+				continue;
+			}
+			CTR1(KTR_MLD, "%s: append node", __func__);
+			if (!m_append(m, sizeof(struct in6_addr),
+			    (void *)&ims->im6s_addr)) {
+				if (m != m0)
+					m_freem(m);
+				CTR1(KTR_MLD, "%s: m_append() failed.",
+				    __func__);
+				return (-ENOMEM);
+			}
+			++msrcs;
+			if (msrcs == m0srcs)
+				break;
+		}
+		pmr->mr_numsrc = htons(msrcs);
+		nbytes += (msrcs * sizeof(struct in6_addr));
+
+		CTR1(KTR_MLD, "%s: enqueueing next packet", __func__);
+		_IF_ENQUEUE(ifq, m);
+	}
+
+	return (nbytes);
+}
+
+/*
+ * Type used to mark record pass completion.
+ * We exploit the fact we can cast to this easily from the
+ * current filter modes on each ip_msource node.
+ */
+typedef enum {
+	REC_NONE = 0x00,	/* MCAST_UNDEFINED */
+	REC_ALLOW = 0x01,	/* MCAST_INCLUDE */
+	REC_BLOCK = 0x02,	/* MCAST_EXCLUDE */
+	REC_FULL = REC_ALLOW | REC_BLOCK
+} rectype_t;
+
+/*
+ * Enqueue an MLDv2 filter list change to the given output queue.
+ *
+ * Source list filter state is held in an RB-tree. When the filter list
+ * for a group is changed without changing its mode, we need to compute
+ * the deltas between T0 and T1 for each source in the filter set,
+ * and enqueue the appropriate ALLOW_NEW/BLOCK_OLD records.
+ *
+ * As we may potentially queue two record types, and the entire R-B tree
+ * needs to be walked at once, we break this out into its own function
+ * so we can generate a tightly packed queue of packets.
+ *
+ * XXX This could be written to only use one tree walk, although that makes
+ * serializing into the mbuf chains a bit harder. For now we do two walks
+ * which makes things easier on us, and it may or may not be harder on
+ * the L2 cache.
+ *
+ * If successful the size of all data appended to the queue is returned,
+ * otherwise an error code less than zero is returned, or zero if
+ * no record(s) were appended.
+ */
+static int
+mld_v2_enqueue_filter_change(struct ifqueue *ifq, struct in6_multi *inm)
+{
+	static const int MINRECLEN =
+	    sizeof(struct mldv2_record) + sizeof(struct in6_addr);
+	struct ifnet		*ifp;
+	struct mldv2_record	 mr;
+	struct mldv2_record	*pmr;
+	struct ip6_msource	*ims, *nims;
+	struct mbuf		*m, *m0, *md;
+	int			 m0srcs, nbytes, npbytes, off, rsrcs, schanged;
+	int			 nallow, nblock;
+	uint8_t			 mode, now, then;
+	rectype_t		 crt, drt, nrt;
+#ifdef KTR
+	char			 ip6tbuf[INET6_ADDRSTRLEN];
+#endif
 
+	IN6_MULTI_LOCK_ASSERT();
+
+	if (inm->in6m_nsrc == 0 ||
+	    (inm->in6m_st[0].iss_asm > 0 && inm->in6m_st[1].iss_asm > 0))
+		return (0);
+
+	ifp = inm->in6m_ifp;			/* interface */
+	mode = inm->in6m_st[1].iss_fmode;	/* filter mode at t1 */
+	crt = REC_NONE;	/* current group record type */
+	drt = REC_NONE;	/* mask of completed group record types */
+	nrt = REC_NONE;	/* record type for current node */
+	m0srcs = 0;	/* # source which will fit in current mbuf chain */
+	npbytes = 0;	/* # of bytes appended this packet */
+	nbytes = 0;	/* # of bytes appended to group's state-change queue */
+	rsrcs = 0;	/* # sources encoded in current record */
+	schanged = 0;	/* # nodes encoded in overall filter change */
+	nallow = 0;	/* # of source entries in ALLOW_NEW */
+	nblock = 0;	/* # of source entries in BLOCK_OLD */
+	nims = NULL;	/* next tree node pointer */
+
+	/*
+	 * For each possible filter record mode.
+	 * The first kind of source we encounter tells us which
+	 * is the first kind of record we start appending.
+	 * If a node transitioned to UNDEFINED at t1, its mode is treated
+	 * as the inverse of the group's filter mode.
+	 */
+	while (drt != REC_FULL) {
+		do {
+			m0 = ifq->ifq_tail;
+			if (m0 != NULL &&
+			    (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <=
+			     MLD_V2_REPORT_MAXRECS) &&
+			    (m0->m_pkthdr.len + MINRECLEN) <
+			     (ifp->if_mtu - MLD_MTUSPACE)) {
+				m = m0;
+				m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
+					    sizeof(struct mldv2_record)) /
+					    sizeof(struct in6_addr);
+				CTR1(KTR_MLD,
+				    "%s: use previous packet", __func__);
+			} else {
+				m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
+				if (m == NULL)
+					m = m_gethdr(M_DONTWAIT, MT_DATA);
+				if (m == NULL) {
+					CTR1(KTR_MLD,
+					    "%s: m_get*() failed", __func__);
+					return (-ENOMEM);
+				}
+				m->m_pkthdr.PH_vt.vt_nrecs = 0;
+				mld_save_context(m, ifp);
+				m0srcs = (ifp->if_mtu - MLD_MTUSPACE -
+				    sizeof(struct mldv2_record)) /
+				    sizeof(struct in6_addr);
+				npbytes = 0;
+				CTR1(KTR_MLD,
+				    "%s: allocated new packet", __func__);
+			}
+			/*
+			 * Append the MLD group record header to the
+			 * current packet's data area.
+			 * Recalculate pointer to free space for next
+			 * group record, in case m_append() allocated
+			 * a new mbuf or cluster.
+			 */
+			memset(&mr, 0, sizeof(mr));
+			mr.mr_addr = inm->in6m_addr;
+			in6_clearscope(&mr.mr_addr);
+			if (!m_append(m, sizeof(mr), (void *)&mr)) {
+				if (m != m0)
+					m_freem(m);
+				CTR1(KTR_MLD,
+				    "%s: m_append() failed", __func__);
+				return (-ENOMEM);
+			}
+			npbytes += sizeof(struct mldv2_record);
+			if (m != m0) {
+				/* new packet; offset in chain */
+				md = m_getptr(m, npbytes -
+				    sizeof(struct mldv2_record), &off);
+				pmr = (struct mldv2_record *)(mtod(md,
+				    uint8_t *) + off);
+			} else {
+				/* current packet; offset from last append */
+				md = m_last(m);
+				pmr = (struct mldv2_record *)(mtod(md,
+				    uint8_t *) + md->m_len -
+				    sizeof(struct mldv2_record));
+			}
+			/*
+			 * Begin walking the tree for this record type
+			 * pass, or continue from where we left off
+			 * previously if we had to allocate a new packet.
+			 * Only report deltas in-mode at t1.
+			 * We need not report included sources as allowed
+			 * if we are in inclusive mode on the group,
+			 * however the converse is not true.
+			 */
+			rsrcs = 0;
+			if (nims == NULL) {
+				nims = RB_MIN(ip6_msource_tree,
+				    &inm->in6m_srcs);
+			}
+			RB_FOREACH_FROM(ims, ip6_msource_tree, nims) {
+				CTR2(KTR_MLD, "%s: visit node %s", __func__,
+				    ip6_sprintf(ip6tbuf, &ims->im6s_addr));
+				now = im6s_get_mode(inm, ims, 1);
+				then = im6s_get_mode(inm, ims, 0);
+				CTR3(KTR_MLD, "%s: mode: t0 %d, t1 %d",
+				    __func__, then, now);
+				if (now == then) {
+					CTR1(KTR_MLD,
+					    "%s: skip unchanged", __func__);
+					continue;
+				}
+				if (mode == MCAST_EXCLUDE &&
+				    now == MCAST_INCLUDE) {
+					CTR1(KTR_MLD,
+					    "%s: skip IN src on EX group",
+					    __func__);
+					continue;
+				}
+				nrt = (rectype_t)now;
+				if (nrt == REC_NONE)
+					nrt = (rectype_t)(~mode & REC_FULL);
+				if (schanged++ == 0) {
+					crt = nrt;
+				} else if (crt != nrt)
+					continue;
+				if (!m_append(m, sizeof(struct in6_addr),
+				    (void *)&ims->im6s_addr)) {
+					if (m != m0)
+						m_freem(m);
+					CTR1(KTR_MLD,
+					    "%s: m_append() failed", __func__);
+					return (-ENOMEM);
+				}
+				nallow += !!(crt == REC_ALLOW);
+				nblock += !!(crt == REC_BLOCK);
+				if (++rsrcs == m0srcs)
+					break;
+			}
+			/*
+			 * If we did not append any tree nodes on this
+			 * pass, back out of allocations.
+			 */
+			if (rsrcs == 0) {
+				npbytes -= sizeof(struct mldv2_record);
+				if (m != m0) {
+					CTR1(KTR_MLD,
+					    "%s: m_free(m)", __func__);
+					m_freem(m);
+				} else {
+					CTR1(KTR_MLD,
+					    "%s: m_adj(m, -mr)", __func__);
+					m_adj(m, -((int)sizeof(
+					    struct mldv2_record)));
+				}
+				continue;
+			}
+			npbytes += (rsrcs * sizeof(struct in6_addr));
+			if (crt == REC_ALLOW)
+				pmr->mr_type = MLD_ALLOW_NEW_SOURCES;
+			else if (crt == REC_BLOCK)
+				pmr->mr_type = MLD_BLOCK_OLD_SOURCES;
+			pmr->mr_numsrc = htons(rsrcs);
+			/*
+			 * Count the new group record, and enqueue this
+			 * packet if it wasn't already queued.
+			 */
+			m->m_pkthdr.PH_vt.vt_nrecs++;
+			if (m != m0)
+				_IF_ENQUEUE(ifq, m);
+			nbytes += npbytes;
+		} while (nims != NULL);
+		drt |= crt;
+		crt = (~crt & REC_FULL);
+	}
+
+	CTR3(KTR_MLD, "%s: queued %d ALLOW_NEW, %d BLOCK_OLD", __func__,
+	    nallow, nblock);
+
+	return (nbytes);
+}
+
+static int
+mld_v2_merge_state_changes(struct in6_multi *inm, struct ifqueue *ifscq)
+{
+	struct ifqueue	*gq;
+	struct mbuf	*m;		/* pending state-change */
+	struct mbuf	*m0;		/* copy of pending state-change */
+	struct mbuf	*mt;		/* last state-change in packet */
+	int		 docopy, domerge;
+	u_int		 recslen;
+
+	docopy = 0;
+	domerge = 0;
+	recslen = 0;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	/*
+	 * If there are further pending retransmissions, make a writable
+	 * copy of each queued state-change message before merging.
+	 */
+	if (inm->in6m_scrv > 0)
+		docopy = 1;
+
+	gq = &inm->in6m_scq;
+#ifdef KTR
+	if (gq->ifq_head == NULL) {
+		CTR2(KTR_MLD, "%s: WARNING: queue for inm %p is empty",
+		    __func__, inm);
+	}
+#endif
+
+	m = gq->ifq_head;
+	while (m != NULL) {
 		/*
-		 * If ifma->ifma_protospec is null, then if_addmulti() created
-		 * a new record.  Otherwise, bump refcount, and we are done.
+		 * Only merge the report into the current packet if
+		 * there is sufficient space to do so; an MLDv2 report
+		 * packet may only contain 65,535 group records.
+		 * Always use a simple mbuf chain concatentation to do this,
+		 * as large state changes for single groups may have
+		 * allocated clusters.
 		 */
-		if (ifma->ifma_protospec != NULL) {
-			in6m = ifma->ifma_protospec;
-			++in6m->in6m_refcount;
-			break;
+		domerge = 0;
+		mt = ifscq->ifq_tail;
+		if (mt != NULL) {
+			recslen = m_length(m, NULL);
+
+			if ((mt->m_pkthdr.PH_vt.vt_nrecs +
+			    m->m_pkthdr.PH_vt.vt_nrecs <=
+			    MLD_V2_REPORT_MAXRECS) &&
+			    (mt->m_pkthdr.len + recslen <=
+			    (inm->in6m_ifp->if_mtu - MLD_MTUSPACE)))
+				domerge = 1;
 		}
 
-		nin6m = malloc(sizeof(*nin6m), M_IP6MADDR, M_NOWAIT | M_ZERO);
-		if (nin6m == NULL) {
-			if_delmulti_ifma(ifma);
-			break;
+		if (!domerge && _IF_QFULL(gq)) {
+			CTR2(KTR_MLD,
+			    "%s: outbound queue full, skipping whole packet %p",
+			    __func__, m);
+			mt = m->m_nextpkt;
+			if (!docopy)
+				m_freem(m);
+			m = mt;
+			continue;
 		}
 
-		nin6m->in6m_addr = *maddr6;
-		nin6m->in6m_ifp = ifp;
-		nin6m->in6m_refcount = 1;
-		nin6m->in6m_ifma = ifma;
-		ifma->ifma_protospec = nin6m;
+		if (!docopy) {
+			CTR2(KTR_MLD, "%s: dequeueing %p", __func__, m);
+			_IF_DEQUEUE(gq, m0);
+			m = m0->m_nextpkt;
+		} else {
+			CTR2(KTR_MLD, "%s: copying %p", __func__, m);
+			m0 = m_dup(m, M_NOWAIT);
+			if (m0 == NULL)
+				return (ENOMEM);
+			m0->m_nextpkt = NULL;
+			m = m->m_nextpkt;
+		}
 
-		nin6m->in6m_timer_ch = malloc(sizeof(*nin6m->in6m_timer_ch),
-		    M_IP6MADDR, M_NOWAIT);
-		if (nin6m->in6m_timer_ch == NULL) {
-			free(nin6m, M_IP6MADDR);
-			if_delmulti_ifma(ifma);
-			break;
+		if (!domerge) {
+			CTR3(KTR_MLD, "%s: queueing %p to ifscq %p)",
+			    __func__, m0, ifscq);
+			_IF_ENQUEUE(ifscq, m0);
+		} else {
+			struct mbuf *mtl;	/* last mbuf of packet mt */
+
+			CTR3(KTR_MLD, "%s: merging %p with ifscq tail %p)",
+			    __func__, m0, mt);
+
+			mtl = m_last(mt);
+			m0->m_flags &= ~M_PKTHDR;
+			mt->m_pkthdr.len += recslen;
+			mt->m_pkthdr.PH_vt.vt_nrecs +=
+			    m0->m_pkthdr.PH_vt.vt_nrecs;
+
+			mtl->m_next = m0;
 		}
+	}
+
+	return (0);
+}
+
+/*
+ * Respond to a pending MLDv2 General Query.
+ */
+static void
+mld_v2_dispatch_general_query(struct mld_ifinfo *mli)
+{
+	INIT_VNET_INET6(curvnet);
+	struct ifmultiaddr	*ifma, *tifma;
+	struct ifnet		*ifp;
+	struct in6_multi	*inm;
+	int			 retval;
+
+	IN6_MULTI_LOCK_ASSERT();
+	MLD_LOCK_ASSERT();
+
+	KASSERT(mli->mli_version == MLD_VERSION_2,
+	    ("%s: called when version %d", __func__, mli->mli_version));
+
+	ifp = mli->mli_ifp;
+
+	IF_ADDR_LOCK(ifp);
+	TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link, tifma) {
+		if (ifma->ifma_addr->sa_family != AF_INET6 ||
+		    ifma->ifma_protospec == NULL)
+			continue;
 
-		LIST_INSERT_HEAD(&in6_multihead, nin6m, in6m_entry);
+		inm = (struct in6_multi *)ifma->ifma_protospec;
+		KASSERT(ifp == inm->in6m_ifp,
+		    ("%s: inconsistent ifp", __func__));
 
-		callout_init(nin6m->in6m_timer_ch, 0);
-		nin6m->in6m_timer = delay;
-		if (nin6m->in6m_timer > 0) {
-			nin6m->in6m_state = MLD_REPORTPENDING;
-			mld_starttimer(nin6m);
+		switch (inm->in6m_state) {
+		case MLD_NOT_MEMBER:
+		case MLD_SILENT_MEMBER:
+			break;
+		case MLD_REPORTING_MEMBER:
+		case MLD_IDLE_MEMBER:
+		case MLD_LAZY_MEMBER:
+		case MLD_SLEEPING_MEMBER:
+		case MLD_AWAKENING_MEMBER:
+			inm->in6m_state = MLD_REPORTING_MEMBER;
+			retval = mld_v2_enqueue_group_record(&mli->mli_gq,
+			    inm, 0, 0, 0);
+			CTR2(KTR_MLD, "%s: enqueue record = %d",
+			    __func__, retval);
+			break;
+		case MLD_G_QUERY_PENDING_MEMBER:
+		case MLD_SG_QUERY_PENDING_MEMBER:
+		case MLD_LEAVING_MEMBER:
+			break;
 		}
+	}
+	IF_ADDR_UNLOCK(ifp);
+
+	mld_dispatch_queue(&mli->mli_gq, MLD_MAX_RESPONSE_BURST);
+
+	/*
+	 * Slew transmission of bursts over 500ms intervals.
+	 */
+	if (mli->mli_gq.ifq_head != NULL) {
+		mli->mli_v2_timer = 1 + MLD_RANDOM_DELAY(
+		    MLD_RESPONSE_BURST_INTERVAL);
+		V_interface_timers_running6 = 1;
+	}
+}
+
+/*
+ * Transmit the next pending message in the output queue.
+ *
+ * VIMAGE: Needs to store/restore vnet pointer on a per-mbuf-chain basis.
+ * MRT: Nothing needs to be done, as MLD traffic is always local to
+ * a link and uses a link-scope multicast address.
+ */
+static void
+mld_dispatch_packet(struct mbuf *m)
+{
+	struct ip6_moptions	 im6o;
+	struct ifnet		*ifp;
+	struct ifnet		*oifp;
+	struct mbuf		*m0;
+	struct mbuf		*md;
+	struct ip6_hdr		*ip6;
+	struct mld_hdr		*mld;
+	int			 error;
+	int			 off;
+	int			 type;
+	uint32_t		 ifindex;
+
+	CTR2(KTR_MLD, "%s: transmit %p", __func__, m);
+
+	/*
+	 * Set VNET image pointer from enqueued mbuf chain
+	 * before doing anything else. Whilst we use interface
+	 * indexes to guard against interface detach, they are
+	 * unique to each VIMAGE and must be retrieved.
+	 */
+	CURVNET_SET(m->m_pkthdr.header);
+	INIT_VNET_NET(curvnet);
+	INIT_VNET_INET6(curvnet);
+	ifindex = mld_restore_context(m);
+
+	/*
+	 * Check if the ifnet still exists. This limits the scope of
+	 * any race in the absence of a global ifp lock for low cost
+	 * (an array lookup).
+	 */
+	ifp = ifnet_byindex(ifindex);
+	if (ifp == NULL) {
+		CTR3(KTR_MLD, "%s: dropped %p as ifindex %u went away.",
+		    __func__, m, ifindex);
+		m_freem(m);
+		IP6STAT_INC(ip6s_noroute);
+		goto out;
+	}
 
-		mld6_start_listening(nin6m);
+	im6o.im6o_multicast_hlim  = 1;
+	im6o.im6o_multicast_loop = (V_ip6_mrouter != NULL);
+	im6o.im6o_multicast_ifp = ifp;
 
-		in6m = nin6m;
+	if (m->m_flags & M_MLDV1) {
+		m0 = m;
+	} else {
+		m0 = mld_v2_encap_report(ifp, m);
+		if (m0 == NULL) {
+			CTR2(KTR_MLD, "%s: dropped %p", __func__, m);
+			m_freem(m);
+			IP6STAT_INC(ip6s_odropped);
+			goto out;
+		}
+	}
 
-	} while (0);
+	mld_scrub_context(m0);
+	m->m_flags &= ~(M_PROTOFLAGS);
+	m0->m_pkthdr.rcvif = V_loif;
 
-	/*IN6_MULTI_UNLOCK();*/
+	ip6 = mtod(m0, struct ip6_hdr *);
+#if 0
+	(void)in6_setscope(&ip6->ip6_dst, ifp, NULL);	/* XXX LOR */
+#else
+	/*
+	 * XXX XXX Break some KPI rules to prevent an LOR which would
+	 * occur if we called in6_setscope() at transmission.
+	 * See comments at top of file.
+	 */
+	MLD_EMBEDSCOPE(&ip6->ip6_dst, ifp->if_index);
+#endif
 
-	return (in6m);
+	/*
+	 * Retrieve the ICMPv6 type before handoff to ip6_output(),
+	 * so we can bump the stats.
+	 */
+	md = m_getptr(m0, sizeof(struct ip6_hdr), &off);
+	mld = (struct mld_hdr *)(mtod(md, uint8_t *) + off);
+	type = mld->mld_type;
+
+	error = ip6_output(m0, &mld_po, NULL, IPV6_UNSPECSRC, &im6o,
+	    &oifp, NULL);
+	if (error) {
+		CTR3(KTR_MLD, "%s: ip6_output(%p) = %d", __func__, m0, error);
+		goto out;
+	}
+	ICMP6STAT_INC(icp6s_outhist[type]);
+	if (oifp != NULL) {
+		icmp6_ifstat_inc(oifp, ifs6_out_msg);
+		switch (type) {
+		case MLD_LISTENER_REPORT:
+		case MLDV2_LISTENER_REPORT:
+			icmp6_ifstat_inc(oifp, ifs6_out_mldreport);
+			break;
+		case MLD_LISTENER_DONE:
+			icmp6_ifstat_inc(oifp, ifs6_out_mlddone);
+			break;
+		}
+	}
+out:
+	/*
+	 * We must restore the existing vnet pointer before continuing.
+	 */
+	CURVNET_RESTORE();
 }
 
 /*
- * Delete a multicast address record.
+ * Encapsulate an MLDv2 report.
+ *
+ * KAME IPv6 requires that hop-by-hop options be passed separately,
+ * and that the IPv6 header be prepended in a separate mbuf.
  *
- * TODO: Locking, as per netinet.
+ * Returns a pointer to the new mbuf chain head, or NULL if the
+ * allocation failed.
  */
-void
-in6_delmulti(struct in6_multi *in6m)
+static struct mbuf *
+mld_v2_encap_report(struct ifnet *ifp, struct mbuf *m)
 {
-	struct ifmultiaddr *ifma;
+	INIT_VNET_INET6(curvnet);
+	struct mbuf		*mh;
+	struct mldv2_report	*mld;
+	struct ip6_hdr		*ip6;
+	struct in6_ifaddr	*ia;
+	int			 mldreclen;
+
+	KASSERT(ifp != NULL, ("%s: null ifp", __func__));
+	KASSERT((m->m_flags & M_PKTHDR),
+	    ("%s: mbuf chain %p is !M_PKTHDR", __func__, m));
+
+	/*
+	 * RFC3590: OK to send as :: or tentative during DAD.
+	 */
+	ia = in6ifa_ifpforlinklocal(ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
+	if (ia == NULL)
+		CTR1(KTR_MLD, "%s: warning: ia is NULL", __func__);
 
-	KASSERT(in6m->in6m_refcount >= 1, ("%s: freeing freed in6m", __func__));
+	MGETHDR(mh, M_DONTWAIT, MT_HEADER);
+	if (mh == NULL) {
+		m_freem(m);
+		return (NULL);
+	}
+	MH_ALIGN(mh, sizeof(struct ip6_hdr) + sizeof(struct mldv2_report));
 
-	if (--in6m->in6m_refcount == 0) {
-		mld_stoptimer(in6m);
-		mld6_stop_listening(in6m);
+	mldreclen = m_length(m, NULL);
+	CTR2(KTR_MLD, "%s: mldreclen is %d", __func__, mldreclen);
 
-		ifma = in6m->in6m_ifma;
-		KASSERT(ifma->ifma_protospec == in6m,
-		    ("%s: ifma_protospec != in6m", __func__));
-		ifma->ifma_protospec = NULL;
+	mh->m_len = sizeof(struct ip6_hdr) + sizeof(struct mldv2_report);
+	mh->m_pkthdr.len = sizeof(struct ip6_hdr) +
+	    sizeof(struct mldv2_report) + mldreclen;
 
-		LIST_REMOVE(in6m, in6m_entry);
-		free(in6m->in6m_timer_ch, M_IP6MADDR);
-		free(in6m, M_IP6MADDR);
+	ip6 = mtod(mh, struct ip6_hdr *);
+	ip6->ip6_flow = 0;
+	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
+	ip6->ip6_vfc |= IPV6_VERSION;
+	ip6->ip6_nxt = IPPROTO_ICMPV6;
+	ip6->ip6_src = ia ? ia->ia_addr.sin6_addr : in6addr_any;
+	ip6->ip6_dst = in6addr_linklocal_allv2routers;
+	/* scope ID will be set in netisr */
+
+	mld = (struct mldv2_report *)(ip6 + 1);
+	mld->mld_type = MLDV2_LISTENER_REPORT;
+	mld->mld_code = 0;
+	mld->mld_cksum = 0;
+	mld->mld_v2_reserved = 0;
+	mld->mld_v2_numrecs = htons(m->m_pkthdr.PH_vt.vt_nrecs);
+	m->m_pkthdr.PH_vt.vt_nrecs = 0;
+
+	mh->m_next = m;
+	mld->mld_cksum = in6_cksum(mh, IPPROTO_ICMPV6,
+	    sizeof(struct ip6_hdr), sizeof(struct mldv2_report) + mldreclen);
+
+	return (mh);
+}
+
+#ifdef KTR
+static char *
+mld_rec_type_to_str(const int type)
+{
 
-		if_delmulti_ifma(ifma);
+	switch (type) {
+		case MLD_CHANGE_TO_EXCLUDE_MODE:
+			return "TO_EX";
+			break;
+		case MLD_CHANGE_TO_INCLUDE_MODE:
+			return "TO_IN";
+			break;
+		case MLD_MODE_IS_EXCLUDE:
+			return "MODE_EX";
+			break;
+		case MLD_MODE_IS_INCLUDE:
+			return "MODE_IN";
+			break;
+		case MLD_ALLOW_NEW_SOURCES:
+			return "ALLOW_NEW";
+			break;
+		case MLD_BLOCK_OLD_SOURCES:
+			return "BLOCK_OLD";
+			break;
+		default:
+			break;
 	}
+	return "unknown";
+}
+#endif
+
+static void
+mld_sysinit(void)
+{
+
+	CTR1(KTR_MLD, "%s: initializing", __func__);
+	MLD_LOCK_INIT();
+
+	ip6_initpktopts(&mld_po);
+	mld_po.ip6po_hlim = 1;
+	mld_po.ip6po_hbh = &mld_ra.hbh;
+	mld_po.ip6po_prefer_tempaddr = IP6PO_TEMPADDR_NOTPREFER;
+	mld_po.ip6po_flags = IP6PO_DONTFRAG;
 }
+
+static void
+mld_sysuninit(void)
+{
+
+	CTR1(KTR_MLD, "%s: tearing down", __func__);
+	MLD_LOCK_DESTROY();
+}
+
+/*
+ * Initialize an MLDv2 instance.
+ * VIMAGE: Assumes curvnet set by caller and called per vimage.
+ */
+static int
+vnet_mld_iattach(const void *unused __unused)
+{
+	INIT_VNET_INET6(curvnet);
+
+	CTR1(KTR_MLD, "%s: initializing", __func__);
+
+	LIST_INIT(&V_mli_head);
+
+	V_current_state_timers_running6 = 0;
+	V_interface_timers_running6 = 0;
+	V_state_change_timers_running6 = 0;
+
+	/*
+	 * Initialize sysctls to default values.
+	 */
+	V_mld_gsrdelay.tv_sec = 10;
+	V_mld_gsrdelay.tv_usec = 0;
+
+	return (0);
+}
+
+static int
+vnet_mld_idetach(const void *unused __unused)
+{
+	INIT_VNET_INET6(curvnet);
+
+	CTR1(KTR_MLD, "%s: tearing down", __func__);
+
+	KASSERT(LIST_EMPTY(&V_mli_head),
+	    ("%s: mli list not empty; ifnets not detached?", __func__));
+
+	return (0);
+}
+
+#ifndef VIMAGE_GLOBALS
+static vnet_modinfo_t vnet_mld_modinfo = {
+	.vmi_id		= VNET_MOD_MLD,
+	.vmi_name	= "mld",
+	.vmi_dependson	= VNET_MOD_INET6,
+	.vmi_iattach	= vnet_mld_iattach,
+	.vmi_idetach	= vnet_mld_idetach
+};
+#endif
+
+static int
+mld_modevent(module_t mod, int type, void *unused __unused)
+{
+
+    switch (type) {
+    case MOD_LOAD:
+	mld_sysinit();
+#ifndef VIMAGE_GLOBALS
+	vnet_mod_register(&vnet_mld_modinfo);
+#else
+	vnet_mld_iattach(NULL);
+#endif
+	break;
+    case MOD_UNLOAD:
+#ifndef VIMAGE_GLOBALS
+#ifdef NOTYET
+	vnet_mod_deregister(&vnet_mld_modinfo);
+#endif
+#else
+	vnet_mld_idetach(NULL);
+#endif
+	mld_sysuninit();
+	break;
+    default:
+	return (EOPNOTSUPP);
+    }
+    return (0);
+}
+
+static moduledata_t mld_mod = {
+    "mld",
+    mld_modevent,
+    0
+};
+DECLARE_MODULE(mld, mld_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);