Update to FreeBSD head 2016-08-23

Git mirror commit 9fe7c416e6abb28b1398fd3e5687099846800cfd.

1 files changed, 389 insertions, 398 deletions

diff --git a/freebsd/sys/netinet6/nd6_nbr.c b/freebsd/sys/netinet6/nd6_nbr.c
index cb765549..df50fa93 100644
--- a/freebsd/sys/netinet6/nd6_nbr.c
+++ b/freebsd/sys/netinet6/nd6_nbr.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include <rtems/bsd/sys/param.h>
 #include <sys/systm.h>
 #include <sys/malloc.h>
+#include <sys/libkern.h>
 #include <rtems/bsd/sys/lock.h>
 #include <sys/rwlock.h>
 #include <sys/mbuf.h>
@@ -50,9 +51,11 @@ __FBSDID("$FreeBSD$");
 #include <sys/time.h>
 #include <sys/kernel.h>
 #include <rtems/bsd/sys/errno.h>
+#include <sys/sysctl.h>
 #include <sys/syslog.h>
 #include <sys/queue.h>
 #include <sys/callout.h>
+#include <sys/refcount.h>
 
 #include <net/if.h>
 #include <net/if_types.h>
@@ -62,11 +65,11 @@ __FBSDID("$FreeBSD$");
 #ifdef RADIX_MPATH
 #include <net/radix_mpath.h>
 #endif
+#include <net/vnet.h>
 
 #include <netinet/in.h>
 #include <netinet/in_var.h>
 #include <net/if_llatbl.h>
-#define	L3_ADDR_SIN6(le)	((struct sockaddr_in6 *) L3_ADDR(le))
 #include <netinet6/in6_var.h>
 #include <netinet6/in6_ifattach.h>
 #include <netinet/ip6.h>
@@ -80,19 +83,32 @@ __FBSDID("$FreeBSD$");
 #define SDL(s) ((struct sockaddr_dl *)s)
 
 struct dadq;
-static struct dadq *nd6_dad_find(struct ifaddr *);
-static void nd6_dad_starttimer(struct dadq *, int);
+static struct dadq *nd6_dad_find(struct ifaddr *, struct nd_opt_nonce *);
+static void nd6_dad_add(struct dadq *dp);
+static void nd6_dad_del(struct dadq *dp);
+static void nd6_dad_rele(struct dadq *);
+static void nd6_dad_starttimer(struct dadq *, int, int);
 static void nd6_dad_stoptimer(struct dadq *);
 static void nd6_dad_timer(struct dadq *);
-static void nd6_dad_ns_output(struct dadq *, struct ifaddr *);
-static void nd6_dad_ns_input(struct ifaddr *);
+static void nd6_dad_duplicated(struct ifaddr *, struct dadq *);
+static void nd6_dad_ns_output(struct dadq *);
+static void nd6_dad_ns_input(struct ifaddr *, struct nd_opt_nonce *);
 static void nd6_dad_na_input(struct ifaddr *);
 static void nd6_na_output_fib(struct ifnet *, const struct in6_addr *,
     const struct in6_addr *, u_long, int, struct sockaddr *, u_int);
+static void nd6_ns_output_fib(struct ifnet *, const struct in6_addr *,
+    const struct in6_addr *, const struct in6_addr *, uint8_t *, u_int);
 
-VNET_DEFINE(int, dad_ignore_ns) = 0;	/* ignore NS in DAD - specwise incorrect*/
-VNET_DEFINE(int, dad_maxtry) = 15;	/* max # of *tries* to transmit DAD packet */
-#define	V_dad_ignore_ns			VNET(dad_ignore_ns)
+static VNET_DEFINE(int, dad_enhanced) = 1;
+#define	V_dad_enhanced			VNET(dad_enhanced)
+
+SYSCTL_DECL(_net_inet6_ip6);
+SYSCTL_INT(_net_inet6_ip6, OID_AUTO, dad_enhanced, CTLFLAG_VNET | CTLFLAG_RW,
+    &VNET_NAME(dad_enhanced), 0,
+    "Enable Enhanced DAD, which adds a random nonce to NS messages for DAD.");
+
+static VNET_DEFINE(int, dad_maxtry) = 15;	/* max # of *tries* to
+						   transmit DAD packet */
 #define	V_dad_maxtry			VNET(dad_maxtry)
 
 /*
@@ -229,42 +245,40 @@ nd6_ns_input(struct mbuf *m, int off, int icmp6len)
 	/* (1) and (3) check. */
 	if (ifp->if_carp)
 		ifa = (*carp_iamatch6_p)(ifp, &taddr6);
-	if (ifa == NULL)
+	else
 		ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
 
 	/* (2) check. */
 	if (ifa == NULL) {
-		struct route_in6 ro;
-		int need_proxy;
+		struct sockaddr_dl rt_gateway;
+		struct rt_addrinfo info;
+		struct sockaddr_in6 dst6;
 
-		bzero(&ro, sizeof(ro));
-		ro.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
-		ro.ro_dst.sin6_family = AF_INET6;
-		ro.ro_dst.sin6_addr = taddr6;
+		bzero(&dst6, sizeof(dst6));
+		dst6.sin6_len = sizeof(struct sockaddr_in6);
+		dst6.sin6_family = AF_INET6;
+		dst6.sin6_addr = taddr6;
+
+		bzero(&rt_gateway, sizeof(rt_gateway));
+		rt_gateway.sdl_len = sizeof(rt_gateway);
+		bzero(&info, sizeof(info));
+		info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&rt_gateway;
 
 		/* Always use the default FIB. */
-#ifdef RADIX_MPATH
-		rtalloc_mpath_fib((struct route *)&ro, RTF_ANNOUNCE,
-		    RT_DEFAULT_FIB);
-#else
-		in6_rtalloc(&ro, RT_DEFAULT_FIB);
-#endif
-		need_proxy = (ro.ro_rt &&
-		    (ro.ro_rt->rt_flags & RTF_ANNOUNCE) != 0 &&
-		    ro.ro_rt->rt_gateway->sa_family == AF_LINK);
-		if (ro.ro_rt != NULL) {
-			if (need_proxy)
-				proxydl = *SDL(ro.ro_rt->rt_gateway);
-			RTFREE(ro.ro_rt);
-		}
-		if (need_proxy) {
-			/*
-			 * proxy NDP for single entry
-			 */
-			ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp,
-				IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
-			if (ifa)
-				proxy = 1;
+		if (rib_lookup_info(RT_DEFAULT_FIB, (struct sockaddr *)&dst6,
+		    0, 0, &info) == 0) {
+			if ((info.rti_flags & RTF_ANNOUNCE) != 0 &&
+			    rt_gateway.sdl_family == AF_LINK) {
+
+				/*
+				 * proxy NDP for single entry
+				 */
+				proxydl = *SDL(&rt_gateway);
+				ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(
+				    ifp, IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
+				if (ifa)
+					proxy = 1;
+			}
 		}
 	}
 	if (ifa == NULL) {
@@ -316,7 +330,7 @@ nd6_ns_input(struct mbuf *m, int off, int icmp6len)
 		 * silently ignore it.
 		 */
 		if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
-			nd6_dad_ns_input(ifa);
+			nd6_dad_ns_input(ifa, ndopts.nd_opts_nonce);
 
 		goto freeit;
 	}
@@ -377,12 +391,14 @@ nd6_ns_input(struct mbuf *m, int off, int icmp6len)
  * Based on RFC 2461
  * Based on RFC 2462 (duplicate address detection)
  *
- *   ln - for source address determination
- *  dad - duplicate address detection
+ *    ln - for source address determination
+ * nonce - If non-NULL, NS is used for duplicate address detection and
+ *         the value (length is ND_OPT_NONCE_LEN) is used as a random nonce.
  */
-void
-nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6, 
-    const struct in6_addr *taddr6, struct llentry *ln, int dad)
+static void
+nd6_ns_output_fib(struct ifnet *ifp, const struct in6_addr *saddr6,
+    const struct in6_addr *daddr6, const struct in6_addr *taddr6,
+    uint8_t *nonce, u_int fibnum)
 {
 	struct mbuf *m;
 	struct m_tag *mtag;
@@ -392,7 +408,6 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 	int icmp6len;
 	int maxlen;
 	caddr_t mac;
-	struct route_in6 ro;
 
 	if (IN6_IS_ADDR_MULTICAST(taddr6))
 		return;
@@ -400,27 +415,17 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 	/* estimate the size of message */
 	maxlen = sizeof(*ip6) + sizeof(*nd_ns);
 	maxlen += (sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7;
-	if (max_linkhdr + maxlen >= MCLBYTES) {
-#ifdef DIAGNOSTIC
-		printf("nd6_ns_output: max_linkhdr + maxlen >= MCLBYTES "
-		    "(%d + %d > %d)\n", max_linkhdr, maxlen, MCLBYTES);
-#endif
-		return;
-	}
+	KASSERT(max_linkhdr + maxlen <= MCLBYTES, (
+	    "%s: max_linkhdr + maxlen > MCLBYTES (%d + %d > %d)",
+	    __func__, max_linkhdr, maxlen, MCLBYTES));
 
-	MGETHDR(m, M_DONTWAIT, MT_DATA);
-	if (m && max_linkhdr + maxlen >= MHLEN) {
-		MCLGET(m, M_DONTWAIT);
-		if ((m->m_flags & M_EXT) == 0) {
-			m_free(m);
-			m = NULL;
-		}
-	}
+	if (max_linkhdr + maxlen > MHLEN)
+		m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
+	else
+		m = m_gethdr(M_NOWAIT, MT_DATA);
 	if (m == NULL)
 		return;
-	m->m_pkthdr.rcvif = NULL;
-
-	bzero(&ro, sizeof(ro));
+	M_SETFIB(m, fibnum);
 
 	if (daddr6 == NULL || IN6_IS_ADDR_MULTICAST(daddr6)) {
 		m->m_flags |= M_MCAST;
@@ -431,7 +436,7 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 
 	icmp6len = sizeof(*nd_ns);
 	m->m_pkthdr.len = m->m_len = sizeof(*ip6) + icmp6len;
-	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
+	m->m_data += max_linkhdr;	/* or M_ALIGN() equivalent? */
 
 	/* fill neighbor solicitation packet */
 	ip6 = mtod(m, struct ip6_hdr *);
@@ -453,8 +458,8 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 		if (in6_setscope(&ip6->ip6_dst, ifp, NULL) != 0)
 			goto bad;
 	}
-	if (!dad) {
-		struct ifaddr *ifa;
+	if (nonce == NULL) {
+		struct ifaddr *ifa = NULL;
 
 		/*
 		 * RFC2461 7.2.2:
@@ -466,60 +471,33 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 		 * interface should be used."
 		 *
 		 * We use the source address for the prompting packet
-		 * (saddr6), if:
-		 * - saddr6 is given from the caller (by giving "ln"), and
-		 * - saddr6 belongs to the outgoing interface.
+		 * (saddr6), if saddr6 belongs to the outgoing interface.
 		 * Otherwise, we perform the source address selection as usual.
 		 */
-		struct in6_addr *hsrc;
 
-		hsrc = NULL;
-		if (ln != NULL) {
-			LLE_RLOCK(ln);
-			if (ln->la_hold != NULL) {
-				struct ip6_hdr *hip6;		/* hold ip6 */
-
-				/*
-				 * assuming every packet in la_hold has the same IP
-				 * header
-				 */
-				hip6 = mtod(ln->la_hold, struct ip6_hdr *);
-				/* XXX pullup? */
-				if (sizeof(*hip6) < ln->la_hold->m_len) {
-					ip6->ip6_src = hip6->ip6_src;
-					hsrc = &hip6->ip6_src;
-				}
-			}
-			LLE_RUNLOCK(ln);
-		}
-		if (hsrc && (ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp,
-		    hsrc)) != NULL) {
+		if (saddr6 != NULL)
+			ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, saddr6);
+		if (ifa != NULL) {
 			/* ip6_src set already. */
+			ip6->ip6_src = *saddr6;
 			ifa_free(ifa);
 		} else {
 			int error;
-			struct sockaddr_in6 dst_sa;
-			struct in6_addr src_in;
-			struct ifnet *oifp;
-
-			bzero(&dst_sa, sizeof(dst_sa));
-			dst_sa.sin6_family = AF_INET6;
-			dst_sa.sin6_len = sizeof(dst_sa);
-			dst_sa.sin6_addr = ip6->ip6_dst;
-
-			oifp = ifp;
-			error = in6_selectsrc(&dst_sa, NULL,
-			    NULL, &ro, NULL, &oifp, &src_in);
+			struct in6_addr dst6, src6;
+			uint32_t scopeid;
+
+			in6_splitscope(&ip6->ip6_dst, &dst6, &scopeid);
+			error = in6_selectsrc_addr(RT_DEFAULT_FIB, &dst6,
+			    scopeid, ifp, &src6, NULL);
 			if (error) {
 				char ip6buf[INET6_ADDRSTRLEN];
-				nd6log((LOG_DEBUG,
-				    "nd6_ns_output: source can't be "
-				    "determined: dst=%s, error=%d\n",
-				    ip6_sprintf(ip6buf, &dst_sa.sin6_addr),
+				nd6log((LOG_DEBUG, "%s: source can't be "
+				    "determined: dst=%s, error=%d\n", __func__,
+				    ip6_sprintf(ip6buf, &dst6),
 				    error));
 				goto bad;
 			}
-			ip6->ip6_src = src_in;
+			ip6->ip6_src = src6;
 		}
 	} else {
 		/*
@@ -550,7 +528,7 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 	 *	Multicast NS		MUST add one	add the option
 	 *	Unicast NS		SHOULD add one	add the option
 	 */
-	if (!dad && (mac = nd6_ifptomac(ifp))) {
+	if (nonce == NULL && (mac = nd6_ifptomac(ifp))) {
 		int optlen = sizeof(struct nd_opt_hdr) + ifp->if_addrlen;
 		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_ns + 1);
 		/* 8 byte alignments... */
@@ -564,7 +542,26 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 		nd_opt->nd_opt_len = optlen >> 3;
 		bcopy(mac, (caddr_t)(nd_opt + 1), ifp->if_addrlen);
 	}
+	/*
+	 * Add a Nonce option (RFC 3971) to detect looped back NS messages.
+	 * This behavior is documented as Enhanced Duplicate Address
+	 * Detection in RFC 7527.
+	 * net.inet6.ip6.dad_enhanced=0 disables this.
+	 */
+	if (V_dad_enhanced != 0 && nonce != NULL) {
+		int optlen = sizeof(struct nd_opt_hdr) + ND_OPT_NONCE_LEN;
+		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_ns + 1);
+		/* 8-byte alignment is required. */
+		optlen = (optlen + 7) & ~7;
 
+		m->m_pkthdr.len += optlen;
+		m->m_len += optlen;
+		icmp6len += optlen;
+		bzero((caddr_t)nd_opt, optlen);
+		nd_opt->nd_opt_type = ND_OPT_NONCE;
+		nd_opt->nd_opt_len = optlen >> 3;
+		bcopy(nonce, (caddr_t)(nd_opt + 1), ND_OPT_NONCE_LEN);
+	}
 	ip6->ip6_plen = htons((u_short)icmp6len);
 	nd_ns->nd_ns_cksum = 0;
 	nd_ns->nd_ns_cksum =
@@ -579,24 +576,27 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 		m_tag_prepend(m, mtag);
 	}
 
-	ip6_output(m, NULL, &ro, dad ? IPV6_UNSPECSRC : 0, &im6o, NULL, NULL);
+	ip6_output(m, NULL, NULL, (nonce != NULL) ? IPV6_UNSPECSRC : 0,
+	    &im6o, NULL, NULL);
 	icmp6_ifstat_inc(ifp, ifs6_out_msg);
 	icmp6_ifstat_inc(ifp, ifs6_out_neighborsolicit);
 	ICMP6STAT_INC(icp6s_outhist[ND_NEIGHBOR_SOLICIT]);
 
-	/* We don't cache this route. */
-	RO_RTFREE(&ro);
-
 	return;
 
   bad:
-	if (ro.ro_rt) {
-		RTFREE(ro.ro_rt);
-	}
 	m_freem(m);
-	return;
 }
 
+#ifndef BURN_BRIDGES
+void
+nd6_ns_output(struct ifnet *ifp, const struct in6_addr *saddr6,
+    const struct in6_addr *daddr6, const struct in6_addr *taddr6,uint8_t *nonce)
+{
+
+	nd6_ns_output_fib(ifp, saddr6, daddr6, taddr6, nonce, RT_DEFAULT_FIB);
+}
+#endif
 /*
  * Neighbor advertisement input handling.
  *
@@ -626,8 +626,10 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 	struct llentry *ln = NULL;
 	union nd_opts ndopts;
 	struct mbuf *chain = NULL;
-	struct m_tag *mtag;
 	struct sockaddr_in6 sin6;
+	u_char linkhdr[LLE_MAX_LINKHDR];
+	size_t linkhdrsize;
+	int lladdr_off;
 	char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
 
 	if (ip6->ip6_hlim != 255) {
@@ -653,6 +655,7 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 	is_router = ((flags & ND_NA_FLAG_ROUTER) != 0);
 	is_solicited = ((flags & ND_NA_FLAG_SOLICITED) != 0);
 	is_override = ((flags & ND_NA_FLAG_OVERRIDE) != 0);
+	memset(&sin6, 0, sizeof(sin6));
 
 	taddr6 = nd_na->nd_na_target;
 	if (in6_setscope(&taddr6, ifp, NULL))
@@ -685,7 +688,14 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 		lladdrlen = ndopts.nd_opts_tgt_lladdr->nd_opt_len << 3;
 	}
 
-	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
+	/*
+	 * This effectively disables the DAD check on a non-master CARP
+	 * address.
+	 */
+	if (ifp->if_carp)
+		ifa = (*carp_iamatch6_p)(ifp, &taddr6);
+	else
+		ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
 
 	/*
 	 * Target address matches one of my interface address.
@@ -742,20 +752,21 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 		/*
 		 * Record link-layer address, and update the state.
 		 */
-		bcopy(lladdr, &ln->ll_addr, ifp->if_addrlen);
-		ln->la_flags |= LLE_VALID;
-		EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
-		if (is_solicited) {
-			ln->ln_state = ND6_LLINFO_REACHABLE;
-			ln->ln_byhint = 0;
-			if (!ND6_LLINFO_PERMANENT(ln)) {
-				nd6_llinfo_settimer_locked(ln,
-				    (long)ND_IFINFO(ln->lle_tbl->llt_ifp)->reachable * hz);
-			}
-		} else {
-			ln->ln_state = ND6_LLINFO_STALE;
-			nd6_llinfo_settimer_locked(ln, (long)V_nd6_gctimer * hz);
+		linkhdrsize = sizeof(linkhdr);
+		if (lltable_calc_llheader(ifp, AF_INET6, lladdr,
+		    linkhdr, &linkhdrsize, &lladdr_off) != 0)
+			return;
+
+		if (lltable_try_set_entry_addr(ifp, ln, linkhdr, linkhdrsize,
+		    lladdr_off) == 0) {
+			ln = NULL;
+			goto freeit;
 		}
+		EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
+		if (is_solicited)
+			nd6_llinfo_setstate(ln, ND6_LLINFO_REACHABLE);
+		else
+			nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
 		if ((ln->ln_router = is_router) != 0) {
 			/*
 			 * This means a router's state has changed from
@@ -774,7 +785,7 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 			llchange = 0;
 		else {
 			if (ln->la_flags & LLE_VALID) {
-				if (bcmp(lladdr, &ln->ll_addr, ifp->if_addrlen))
+				if (bcmp(lladdr, ln->ll_addr, ifp->if_addrlen))
 					llchange = 1;
 				else
 					llchange = 0;
@@ -806,10 +817,8 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 			 * If state is REACHABLE, make it STALE.
 			 * no other updates should be done.
 			 */
-			if (ln->ln_state == ND6_LLINFO_REACHABLE) {
-				ln->ln_state = ND6_LLINFO_STALE;
-				nd6_llinfo_settimer_locked(ln, (long)V_nd6_gctimer * hz);
-			}
+			if (ln->ln_state == ND6_LLINFO_REACHABLE)
+				nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
 			goto freeit;
 		} else if (is_override				   /* (2a) */
 			|| (!is_override && (lladdr != NULL && !llchange)) /* (2b) */
@@ -818,8 +827,15 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 			 * Update link-local address, if any.
 			 */
 			if (lladdr != NULL) {
-				bcopy(lladdr, &ln->ll_addr, ifp->if_addrlen);
-				ln->la_flags |= LLE_VALID;
+				linkhdrsize = sizeof(linkhdr);
+				if (lltable_calc_llheader(ifp, AF_INET6, lladdr,
+				    linkhdr, &linkhdrsize, &lladdr_off) != 0)
+					goto freeit;
+				if (lltable_try_set_entry_addr(ifp, ln, linkhdr,
+				    linkhdrsize, lladdr_off) == 0) {
+					ln = NULL;
+					goto freeit;
+				}
 				EVENTHANDLER_INVOKE(lle_event, ln,
 				    LLENTRY_RESOLVED);
 			}
@@ -829,19 +845,11 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 			 * If not solicited and the link-layer address was
 			 * changed, make it STALE.
 			 */
-			if (is_solicited) {
-				ln->ln_state = ND6_LLINFO_REACHABLE;
-				ln->ln_byhint = 0;
-				if (!ND6_LLINFO_PERMANENT(ln)) {
-					nd6_llinfo_settimer_locked(ln,
-					    (long)ND_IFINFO(ifp)->reachable * hz);
-				}
-			} else {
-				if (lladdr != NULL && llchange) {
-					ln->ln_state = ND6_LLINFO_STALE;
-					nd6_llinfo_settimer_locked(ln,
-					    (long)V_nd6_gctimer * hz);
-				}
+			if (is_solicited)
+				nd6_llinfo_setstate(ln, ND6_LLINFO_REACHABLE);
+			else {
+				if (lladdr != NULL && llchange)
+					nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
 			}
 		}
 
@@ -851,31 +859,19 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 			 * Remove the sender from the Default Router List and
 			 * update the Destination Cache entries.
 			 */
-			struct nd_defrouter *dr;
-			struct in6_addr *in6;
-
-			in6 = &L3_ADDR_SIN6(ln)->sin6_addr;
+			struct ifnet *nd6_ifp;
 
-			/*
-			 * Lock to protect the default router list.
-			 * XXX: this might be unnecessary, since this function
-			 * is only called under the network software interrupt
-			 * context.  However, we keep it just for safety.
-			 */
-			dr = defrouter_lookup(in6, ln->lle_tbl->llt_ifp);
-			if (dr)
-				defrtrlist_del(dr);
-			else if (ND_IFINFO(ln->lle_tbl->llt_ifp)->flags &
-			    ND6_IFF_ACCEPT_RTADV) {
+			nd6_ifp = lltable_get_ifp(ln->lle_tbl);
+			if (!defrouter_remove(&ln->r_l3addr.addr6, nd6_ifp) &&
+			    (ND_IFINFO(nd6_ifp)->flags &
+			     ND6_IFF_ACCEPT_RTADV) != 0)
 				/*
 				 * Even if the neighbor is not in the default
-				 * router list, the neighbor may be used
-				 * as a next hop for some destinations
-				 * (e.g. redirect case). So we must
-				 * call rt6_flush explicitly.
+				 * router list, the neighbor may be used as a
+				 * next hop for some destinations (e.g. redirect
+				 * case). So we must call rt6_flush explicitly.
 				 */
 				rt6_flush(&ip6->ip6_src, ifp);
-			}
 		}
 		ln->ln_router = is_router;
 	}
@@ -884,43 +880,15 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 	 *  rt->rt_flags &= ~RTF_REJECT;
 	 */
 	ln->la_asked = 0;
-	if (ln->la_hold) {
-		struct mbuf *m_hold, *m_hold_next;
-
-		/*
-		 * reset the la_hold in advance, to explicitly
-		 * prevent a la_hold lookup in nd6_output()
-		 * (wouldn't happen, though...)
-		 */
-		for (m_hold = ln->la_hold, ln->la_hold = NULL;
-		    m_hold; m_hold = m_hold_next) {
-			m_hold_next = m_hold->m_nextpkt;
-			m_hold->m_nextpkt = NULL;
-			/*
-			 * we assume ifp is not a loopback here, so just set
-			 * the 2nd argument as the 1st one.
-			 */
-
-			if (send_sendso_input_hook != NULL) {
-				mtag = m_tag_get(PACKET_TAG_ND_OUTGOING,
-				    sizeof(unsigned short), M_NOWAIT);
-				if (mtag == NULL)
-					goto bad;
-				m_tag_prepend(m, mtag);
-			}
-
-			nd6_output_lle(ifp, ifp, m_hold, L3_ADDR_SIN6(ln), NULL, ln, &chain);
-		}
-	}
+	if (ln->la_hold != NULL)
+		nd6_grab_holdchain(ln, &chain, &sin6);
  freeit:
-	if (ln != NULL) {
-		if (chain)
-			memcpy(&sin6, L3_ADDR_SIN6(ln), sizeof(sin6));
+	if (ln != NULL)
 		LLE_WUNLOCK(ln);
 
-		if (chain)
-			nd6_output_flush(ifp, ifp, chain, &sin6, NULL);
-	}
+	if (chain != NULL)
+		nd6_flush_holdchain(ifp, ifp, chain, &sin6);
+
 	if (checklink)
 		pfxlist_onlink_check();
 
@@ -954,42 +922,30 @@ nd6_na_output_fib(struct ifnet *ifp, const struct in6_addr *daddr6_0,
 {
 	struct mbuf *m;
 	struct m_tag *mtag;
-	struct ifnet *oifp;
 	struct ip6_hdr *ip6;
 	struct nd_neighbor_advert *nd_na;
 	struct ip6_moptions im6o;
-	struct in6_addr src, daddr6;
-	struct sockaddr_in6 dst_sa;
+	struct in6_addr daddr6, dst6, src6;
+	uint32_t scopeid;
+
 	int icmp6len, maxlen, error;
 	caddr_t mac = NULL;
-	struct route_in6 ro;
-
-	bzero(&ro, sizeof(ro));
 
 	daddr6 = *daddr6_0;	/* make a local copy for modification */
 
 	/* estimate the size of message */
 	maxlen = sizeof(*ip6) + sizeof(*nd_na);
 	maxlen += (sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7;
-	if (max_linkhdr + maxlen >= MCLBYTES) {
-#ifdef DIAGNOSTIC
-		printf("nd6_na_output: max_linkhdr + maxlen >= MCLBYTES "
-		    "(%d + %d > %d)\n", max_linkhdr, maxlen, MCLBYTES);
-#endif
-		return;
-	}
+	KASSERT(max_linkhdr + maxlen <= MCLBYTES, (
+	    "%s: max_linkhdr + maxlen > MCLBYTES (%d + %d > %d)",
+	    __func__, max_linkhdr, maxlen, MCLBYTES));
 
-	MGETHDR(m, M_DONTWAIT, MT_DATA);
-	if (m && max_linkhdr + maxlen >= MHLEN) {
-		MCLGET(m, M_DONTWAIT);
-		if ((m->m_flags & M_EXT) == 0) {
-			m_free(m);
-			m = NULL;
-		}
-	}
+	if (max_linkhdr + maxlen > MHLEN)
+		m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
+	else
+		m = m_gethdr(M_NOWAIT, MT_DATA);
 	if (m == NULL)
 		return;
-	m->m_pkthdr.rcvif = NULL;
 	M_SETFIB(m, fibnum);
 
 	if (IN6_IS_ADDR_MULTICAST(&daddr6)) {
@@ -1001,7 +957,7 @@ nd6_na_output_fib(struct ifnet *ifp, const struct in6_addr *daddr6_0,
 
 	icmp6len = sizeof(*nd_na);
 	m->m_pkthdr.len = m->m_len = sizeof(struct ip6_hdr) + icmp6len;
-	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
+	m->m_data += max_linkhdr;	/* or M_ALIGN() equivalent? */
 
 	/* fill neighbor advertisement packet */
 	ip6 = mtod(m, struct ip6_hdr *);
@@ -1023,25 +979,21 @@ nd6_na_output_fib(struct ifnet *ifp, const struct in6_addr *daddr6_0,
 		flags &= ~ND_NA_FLAG_SOLICITED;
 	}
 	ip6->ip6_dst = daddr6;
-	bzero(&dst_sa, sizeof(struct sockaddr_in6));
-	dst_sa.sin6_family = AF_INET6;
-	dst_sa.sin6_len = sizeof(struct sockaddr_in6);
-	dst_sa.sin6_addr = daddr6;
 
 	/*
 	 * Select a source whose scope is the same as that of the dest.
 	 */
-	bcopy(&dst_sa, &ro.ro_dst, sizeof(dst_sa));
-	oifp = ifp;
-	error = in6_selectsrc(&dst_sa, NULL, NULL, &ro, NULL, &oifp, &src);
+	in6_splitscope(&daddr6, &dst6, &scopeid);
+	error = in6_selectsrc_addr(RT_DEFAULT_FIB, &dst6,
+	    scopeid, ifp, &src6, NULL);
 	if (error) {
 		char ip6buf[INET6_ADDRSTRLEN];
 		nd6log((LOG_DEBUG, "nd6_na_output: source can't be "
 		    "determined: dst=%s, error=%d\n",
-		    ip6_sprintf(ip6buf, &dst_sa.sin6_addr), error));
+		    ip6_sprintf(ip6buf, &daddr6), error));
 		goto bad;
 	}
-	ip6->ip6_src = src;
+	ip6->ip6_src = src6;
 	nd_na = (struct nd_neighbor_advert *)(ip6 + 1);
 	nd_na->nd_na_type = ND_NEIGHBOR_ADVERT;
 	nd_na->nd_na_code = 0;
@@ -1104,22 +1056,15 @@ nd6_na_output_fib(struct ifnet *ifp, const struct in6_addr *daddr6_0,
 		m_tag_prepend(m, mtag);
 	}
 
-	ip6_output(m, NULL, &ro, 0, &im6o, NULL, NULL);
+	ip6_output(m, NULL, NULL, 0, &im6o, NULL, NULL);
 	icmp6_ifstat_inc(ifp, ifs6_out_msg);
 	icmp6_ifstat_inc(ifp, ifs6_out_neighboradvert);
 	ICMP6STAT_INC(icp6s_outhist[ND_NEIGHBOR_ADVERT]);
 
-	/* We don't cache this route. */
-	RO_RTFREE(&ro);
-
 	return;
 
   bad:
-	if (ro.ro_rt) {
-		RTFREE(ro.ro_rt);
-	}
 	m_freem(m);
-	return;
 }
 
 #ifndef BURN_BRIDGES
@@ -1142,15 +1087,8 @@ nd6_ifptomac(struct ifnet *ifp)
 	case IFT_ETHER:
 	case IFT_FDDI:
 	case IFT_IEEE1394:
-#ifdef IFT_L2VLAN
 	case IFT_L2VLAN:
-#endif
-#ifdef IFT_IEEE80211
 	case IFT_IEEE80211:
-#endif
-#ifdef IFT_CARP
-	case IFT_CARP:
-#endif
 	case IFT_INFINIBAND:
 	case IFT_BRIDGE:
 	case IFT_ISO88025:
@@ -1168,31 +1106,80 @@ struct dadq {
 	int dad_ns_ocount;	/* NS sent so far */
 	int dad_ns_icount;
 	int dad_na_icount;
+	int dad_ns_lcount;	/* looped back NS */
+	int dad_loopbackprobe;	/* probing state for loopback detection */
 	struct callout dad_timer_ch;
 	struct vnet *dad_vnet;
+	u_int dad_refcnt;
+#define	ND_OPT_NONCE_LEN32 \
+		((ND_OPT_NONCE_LEN + sizeof(uint32_t) - 1)/sizeof(uint32_t))
+	uint32_t dad_nonce[ND_OPT_NONCE_LEN32];
 };
 
 static VNET_DEFINE(TAILQ_HEAD(, dadq), dadq);
-VNET_DEFINE(int, dad_init) = 0;
-#define	V_dadq				VNET(dadq)
-#define	V_dad_init			VNET(dad_init)
+static VNET_DEFINE(struct rwlock, dad_rwlock);
+#define	V_dadq			VNET(dadq)
+#define	V_dad_rwlock		VNET(dad_rwlock)
+
+#define	DADQ_RLOCK()		rw_rlock(&V_dad_rwlock)	
+#define	DADQ_RUNLOCK()		rw_runlock(&V_dad_rwlock)	
+#define	DADQ_WLOCK()		rw_wlock(&V_dad_rwlock)	
+#define	DADQ_WUNLOCK()		rw_wunlock(&V_dad_rwlock)	
+
+static void
+nd6_dad_add(struct dadq *dp)
+{
+
+	DADQ_WLOCK();
+	TAILQ_INSERT_TAIL(&V_dadq, dp, dad_list);
+	DADQ_WUNLOCK();
+}
+
+static void
+nd6_dad_del(struct dadq *dp)
+{
+
+	DADQ_WLOCK();
+	TAILQ_REMOVE(&V_dadq, dp, dad_list);
+	DADQ_WUNLOCK();
+	nd6_dad_rele(dp);
+}
 
 static struct dadq *
-nd6_dad_find(struct ifaddr *ifa)
+nd6_dad_find(struct ifaddr *ifa, struct nd_opt_nonce *n)
 {
 	struct dadq *dp;
 
-	TAILQ_FOREACH(dp, &V_dadq, dad_list)
-		if (dp->dad_ifa == ifa)
-			return (dp);
+	DADQ_RLOCK();
+	TAILQ_FOREACH(dp, &V_dadq, dad_list) {
+		if (dp->dad_ifa != ifa)
+			continue;
+		/*
+		 * Skip if the nonce matches the received one.
+		 * +2 in the length is required because of type and
+		 * length fields are included in a header.
+		 */
+		if (n != NULL &&
+		    n->nd_opt_nonce_len == (ND_OPT_NONCE_LEN + 2) / 8 &&
+		    memcmp(&n->nd_opt_nonce[0], &dp->dad_nonce[0],
+		        ND_OPT_NONCE_LEN) == 0) {
+			dp->dad_ns_lcount++;
+			continue;
+		}
+		refcount_acquire(&dp->dad_refcnt);
+		break;
+	}
+	DADQ_RUNLOCK();
 
-	return (NULL);
+	return (dp);
 }
 
 static void
-nd6_dad_starttimer(struct dadq *dp, int ticks)
+nd6_dad_starttimer(struct dadq *dp, int ticks, int send_ns)
 {
 
+	if (send_ns != 0)
+		nd6_dad_ns_output(dp);
 	callout_reset(&dp->dad_timer_ch, ticks,
 	    (void (*)(void *))nd6_dad_timer, (void *)dp);
 }
@@ -1201,7 +1188,25 @@ static void
 nd6_dad_stoptimer(struct dadq *dp)
 {
 
-	callout_stop(&dp->dad_timer_ch);
+	callout_drain(&dp->dad_timer_ch);
+}
+
+static void
+nd6_dad_rele(struct dadq *dp)
+{
+
+	if (refcount_release(&dp->dad_refcnt)) {
+		ifa_free(dp->dad_ifa);
+		free(dp, M_IP6NDP);
+	}
+}
+
+void
+nd6_dad_init(void)
+{
+
+	rw_init(&V_dad_rwlock, "nd6 DAD queue");
+	TAILQ_INIT(&V_dadq);
 }
 
 /*
@@ -1214,11 +1219,6 @@ nd6_dad_start(struct ifaddr *ifa, int delay)
 	struct dadq *dp;
 	char ip6buf[INET6_ADDRSTRLEN];
 
-	if (!V_dad_init) {
-		TAILQ_INIT(&V_dadq);
-		V_dad_init++;
-	}
-
 	/*
 	 * If we don't need DAD, don't do it.
 	 * There are several cases:
@@ -1243,17 +1243,26 @@ nd6_dad_start(struct ifaddr *ifa, int delay)
 	}
 	if (ifa->ifa_ifp == NULL)
 		panic("nd6_dad_start: ifa->ifa_ifp == NULL");
-	if (!(ifa->ifa_ifp->if_flags & IFF_UP)) {
+	if (ND_IFINFO(ifa->ifa_ifp)->flags & ND6_IFF_NO_DAD) {
+		ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
 		return;
 	}
-	if (ND_IFINFO(ifa->ifa_ifp)->flags & ND6_IFF_IFDISABLED)
+	if (!(ifa->ifa_ifp->if_flags & IFF_UP) ||
+	    !(ifa->ifa_ifp->if_drv_flags & IFF_DRV_RUNNING) ||
+	    (ND_IFINFO(ifa->ifa_ifp)->flags & ND6_IFF_IFDISABLED)) {
+		ia->ia6_flags |= IN6_IFF_TENTATIVE;
 		return;
-	if (nd6_dad_find(ifa) != NULL) {
-		/* DAD already in progress */
+	}
+	if ((dp = nd6_dad_find(ifa, NULL)) != NULL) {
+		/*
+		 * DAD is already in progress.  Let the existing entry
+		 * finish it.
+		 */
+		nd6_dad_rele(dp);
 		return;
 	}
 
-	dp = malloc(sizeof(*dp), M_IP6NDP, M_NOWAIT);
+	dp = malloc(sizeof(*dp), M_IP6NDP, M_NOWAIT | M_ZERO);
 	if (dp == NULL) {
 		log(LOG_ERR, "nd6_dad_start: memory allocation failed for "
 			"%s(%s)\n",
@@ -1261,13 +1270,10 @@ nd6_dad_start(struct ifaddr *ifa, int delay)
 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
 		return;
 	}
-	bzero(dp, sizeof(*dp));
 	callout_init(&dp->dad_timer_ch, 0);
 #ifdef VIMAGE
 	dp->dad_vnet = curvnet;
 #endif
-	TAILQ_INSERT_TAIL(&V_dadq, (struct dadq *)dp, dad_list);
-
 	nd6log((LOG_DEBUG, "%s: starting DAD for %s\n", if_name(ifa->ifa_ifp),
 	    ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr)));
 
@@ -1278,17 +1284,14 @@ nd6_dad_start(struct ifaddr *ifa, int delay)
 	 * (re)initialization.
 	 */
 	dp->dad_ifa = ifa;
-	ifa_ref(ifa);	/* just for safety */
+	ifa_ref(dp->dad_ifa);
 	dp->dad_count = V_ip6_dad_count;
 	dp->dad_ns_icount = dp->dad_na_icount = 0;
 	dp->dad_ns_ocount = dp->dad_ns_tcount = 0;
-	if (delay == 0) {
-		nd6_dad_ns_output(dp, ifa);
-		nd6_dad_starttimer(dp,
-		    (long)ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000);
-	} else {
-		nd6_dad_starttimer(dp, delay);
-	}
+	dp->dad_ns_lcount = dp->dad_loopbackprobe = 0;
+	refcount_init(&dp->dad_refcnt, 1);
+	nd6_dad_add(dp);
+	nd6_dad_starttimer(dp, delay, 0);
 }
 
 /*
@@ -1299,9 +1302,7 @@ nd6_dad_stop(struct ifaddr *ifa)
 {
 	struct dadq *dp;
 
-	if (!V_dad_init)
-		return;
-	dp = nd6_dad_find(ifa);
+	dp = nd6_dad_find(ifa, NULL);
 	if (!dp) {
 		/* DAD wasn't started yet */
 		return;
@@ -1309,53 +1310,61 @@ nd6_dad_stop(struct ifaddr *ifa)
 
 	nd6_dad_stoptimer(dp);
 
-	TAILQ_REMOVE(&V_dadq, (struct dadq *)dp, dad_list);
-	free(dp, M_IP6NDP);
-	dp = NULL;
-	ifa_free(ifa);
+	/*
+	 * The DAD queue entry may have been removed by nd6_dad_timer() while
+	 * we were waiting for it to stop, so re-do the lookup.
+	 */
+	nd6_dad_rele(dp);
+	if (nd6_dad_find(ifa, NULL) == NULL)
+		return;
+
+	nd6_dad_del(dp);
+	nd6_dad_rele(dp);
 }
 
 static void
 nd6_dad_timer(struct dadq *dp)
 {
 	CURVNET_SET(dp->dad_vnet);
-	int s;
 	struct ifaddr *ifa = dp->dad_ifa;
+	struct ifnet *ifp = dp->dad_ifa->ifa_ifp;
 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
 	char ip6buf[INET6_ADDRSTRLEN];
 
-	s = splnet();		/* XXX */
-
 	/* Sanity check */
 	if (ia == NULL) {
 		log(LOG_ERR, "nd6_dad_timer: called with null parameter\n");
-		goto done;
+		goto err;
+	}
+	if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) {
+		/* Do not need DAD for ifdisabled interface. */
+		log(LOG_ERR, "nd6_dad_timer: cancel DAD on %s because of "
+		    "ND6_IFF_IFDISABLED.\n", ifp->if_xname);
+		goto err;
 	}
 	if (ia->ia6_flags & IN6_IFF_DUPLICATED) {
 		log(LOG_ERR, "nd6_dad_timer: called with duplicated address "
 			"%s(%s)\n",
 			ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr),
 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
-		goto done;
+		goto err;
 	}
 	if ((ia->ia6_flags & IN6_IFF_TENTATIVE) == 0) {
 		log(LOG_ERR, "nd6_dad_timer: called with non-tentative address "
 			"%s(%s)\n",
 			ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr),
 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
-		goto done;
+		goto err;
 	}
 
-	/* timeouted with IFF_{RUNNING,UP} check */
-	if (dp->dad_ns_tcount > V_dad_maxtry) {
-		nd6log((LOG_INFO, "%s: could not run DAD, driver problem?\n",
+	/* Stop DAD if the interface is down even after dad_maxtry attempts. */
+	if ((dp->dad_ns_tcount > V_dad_maxtry) &&
+	    (((ifp->if_flags & IFF_UP) == 0) ||
+	     ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0))) {
+		nd6log((LOG_INFO, "%s: could not run DAD "
+		    "because the interface was down or not running.\n",
 		    if_name(ifa->ifa_ifp)));
-
-		TAILQ_REMOVE(&V_dadq, (struct dadq *)dp, dad_list);
-		free(dp, M_IP6NDP);
-		dp = NULL;
-		ifa_free(ifa);
-		goto done;
+		goto err;
 	}
 
 	/* Need more checks? */
@@ -1363,84 +1372,85 @@ nd6_dad_timer(struct dadq *dp)
 		/*
 		 * We have more NS to go.  Send NS packet for DAD.
 		 */
-		nd6_dad_ns_output(dp, ifa);
 		nd6_dad_starttimer(dp,
-		    (long)ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000);
+		    (long)ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000, 1);
+		goto done;
 	} else {
 		/*
 		 * We have transmitted sufficient number of DAD packets.
 		 * See what we've got.
 		 */
-		int duplicate;
-
-		duplicate = 0;
-
-		if (dp->dad_na_icount) {
+		if (dp->dad_ns_icount > 0 || dp->dad_na_icount > 0)
+			/* We've seen NS or NA, means DAD has failed. */
+			nd6_dad_duplicated(ifa, dp);
+		else if (V_dad_enhanced != 0 &&
+		    dp->dad_ns_lcount > 0 &&
+		    dp->dad_ns_lcount > dp->dad_loopbackprobe) {
 			/*
-			 * the check is in nd6_dad_na_input(),
-			 * but just in case
+			 * Sec. 4.1 in RFC 7527 requires transmission of
+			 * additional probes until the loopback condition
+			 * becomes clear when a looped back probe is detected.
 			 */
-			duplicate++;
-		}
-
-		if (dp->dad_ns_icount) {
-			/* We've seen NS, means DAD has failed. */
-			duplicate++;
-		}
-
-		if (duplicate) {
-			/* (*dp) will be freed in nd6_dad_duplicated() */
-			dp = NULL;
-			nd6_dad_duplicated(ifa);
+			log(LOG_ERR, "%s: a looped back NS message is "
+			    "detected during DAD for %s.  "
+			    "Another DAD probes are being sent.\n",
+			    if_name(ifa->ifa_ifp),
+			    ip6_sprintf(ip6buf, IFA_IN6(ifa)));
+			dp->dad_loopbackprobe = dp->dad_ns_lcount;
+			/*
+			 * Send an NS immediately and increase dad_count by
+			 * V_nd6_mmaxtries - 1.
+			 */
+			dp->dad_count =
+			    dp->dad_ns_ocount + V_nd6_mmaxtries - 1;
+			nd6_dad_starttimer(dp,
+			    (long)ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000,
+			    1);
+			goto done;
 		} else {
 			/*
 			 * We are done with DAD.  No NA came, no NS came.
-			 * No duplicate address found.
+			 * No duplicate address found.  Check IFDISABLED flag
+			 * again in case that it is changed between the
+			 * beginning of this function and here.
 			 */
-			ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
+			if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) == 0)
+				ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
 
 			nd6log((LOG_DEBUG,
 			    "%s: DAD complete for %s - no duplicates found\n",
 			    if_name(ifa->ifa_ifp),
 			    ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr)));
-
-			TAILQ_REMOVE(&V_dadq, (struct dadq *)dp, dad_list);
-			free(dp, M_IP6NDP);
-			dp = NULL;
-			ifa_free(ifa);
+			if (dp->dad_ns_lcount > 0)
+				log(LOG_ERR, "%s: DAD completed while "
+				    "a looped back NS message is detected "
+				    "during DAD for %s.\n",
+				    if_name(ifa->ifa_ifp),
+				    ip6_sprintf(ip6buf, IFA_IN6(ifa)));
 		}
 	}
-
+err:
+	nd6_dad_del(dp);
 done:
-	splx(s);
 	CURVNET_RESTORE();
 }
 
-void
-nd6_dad_duplicated(struct ifaddr *ifa)
+static void
+nd6_dad_duplicated(struct ifaddr *ifa, struct dadq *dp)
 {
 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
 	struct ifnet *ifp;
-	struct dadq *dp;
 	char ip6buf[INET6_ADDRSTRLEN];
 
-	dp = nd6_dad_find(ifa);
-	if (dp == NULL) {
-		log(LOG_ERR, "nd6_dad_duplicated: DAD structure not found\n");
-		return;
-	}
-
 	log(LOG_ERR, "%s: DAD detected duplicate IPv6 address %s: "
-	    "NS in/out=%d/%d, NA in=%d\n",
+	    "NS in/out/loopback=%d/%d/%d, NA in=%d\n",
 	    if_name(ifa->ifa_ifp), ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr),
-	    dp->dad_ns_icount, dp->dad_ns_ocount, dp->dad_na_icount);
+	    dp->dad_ns_icount, dp->dad_ns_ocount, dp->dad_ns_lcount,
+	    dp->dad_na_icount);
 
 	ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
 	ia->ia6_flags |= IN6_IFF_DUPLICATED;
 
-	/* We are done with DAD, with duplicate address found. (failure) */
-	nd6_dad_stoptimer(dp);
-
 	ifp = ifa->ifa_ifp;
 	log(LOG_ERR, "%s: DAD complete for %s - duplicate found\n",
 	    if_name(ifp), ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr));
@@ -1466,9 +1476,7 @@ nd6_dad_duplicated(struct ifaddr *ifa)
 		case IFT_FDDI:
 		case IFT_ATM:
 		case IFT_IEEE1394:
-#ifdef IFT_IEEE80211
 		case IFT_IEEE80211:
-#endif
 		case IFT_INFINIBAND:
 			in6 = ia->ia_addr.sin6_addr;
 			if (in6_get_hw_ifid(ifp, &in6) == 0 &&
@@ -1481,18 +1489,14 @@ nd6_dad_duplicated(struct ifaddr *ifa)
 			break;
 		}
 	}
-
-	TAILQ_REMOVE(&V_dadq, (struct dadq *)dp, dad_list);
-	free(dp, M_IP6NDP);
-	dp = NULL;
-	ifa_free(ifa);
 }
 
 static void
-nd6_dad_ns_output(struct dadq *dp, struct ifaddr *ifa)
+nd6_dad_ns_output(struct dadq *dp)
 {
-	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
-	struct ifnet *ifp = ifa->ifa_ifp;
+	struct in6_ifaddr *ia = (struct in6_ifaddr *)dp->dad_ifa;
+	struct ifnet *ifp = dp->dad_ifa->ifa_ifp;
+	int i;
 
 	dp->dad_ns_tcount++;
 	if ((ifp->if_flags & IFF_UP) == 0) {
@@ -1503,17 +1507,29 @@ nd6_dad_ns_output(struct dadq *dp, struct ifaddr *ifa)
 	}
 
 	dp->dad_ns_ocount++;
-	nd6_ns_output(ifp, NULL, &ia->ia_addr.sin6_addr, NULL, 1);
+	if (V_dad_enhanced != 0) {
+		for (i = 0; i < ND_OPT_NONCE_LEN32; i++)
+			dp->dad_nonce[i] = arc4random();
+		/*
+		 * XXXHRS: Note that in the case that
+		 * DupAddrDetectTransmits > 1, multiple NS messages with
+		 * different nonces can be looped back in an unexpected
+		 * order.  The current implementation recognizes only
+		 * the latest nonce on the sender side.  Practically it
+		 * should work well in almost all cases.
+		 */
+	}
+	nd6_ns_output(ifp, NULL, NULL, &ia->ia_addr.sin6_addr,
+	    (uint8_t *)&dp->dad_nonce[0]);
 }
 
 static void
-nd6_dad_ns_input(struct ifaddr *ifa)
+nd6_dad_ns_input(struct ifaddr *ifa, struct nd_opt_nonce *ndopt_nonce)
 {
 	struct in6_ifaddr *ia;
 	struct ifnet *ifp;
 	const struct in6_addr *taddr6;
 	struct dadq *dp;
-	int duplicate;
 
 	if (ifa == NULL)
 		panic("ifa == NULL in nd6_dad_ns_input");
@@ -1521,39 +1537,15 @@ nd6_dad_ns_input(struct ifaddr *ifa)
 	ia = (struct in6_ifaddr *)ifa;
 	ifp = ifa->ifa_ifp;
 	taddr6 = &ia->ia_addr.sin6_addr;
-	duplicate = 0;
-	dp = nd6_dad_find(ifa);
-
-	/* Quickhack - completely ignore DAD NS packets */
-	if (V_dad_ignore_ns) {
-		char ip6buf[INET6_ADDRSTRLEN];
-		nd6log((LOG_INFO,
-		    "nd6_dad_ns_input: ignoring DAD NS packet for "
-		    "address %s(%s)\n", ip6_sprintf(ip6buf, taddr6),
-		    if_name(ifa->ifa_ifp)));
+	/* Ignore Nonce option when Enhanced DAD is disabled. */
+	if (V_dad_enhanced == 0)
+		ndopt_nonce = NULL;
+	dp = nd6_dad_find(ifa, ndopt_nonce);
+	if (dp == NULL)
 		return;
-	}
-
-	/*
-	 * if I'm yet to start DAD, someone else started using this address
-	 * first.  I have a duplicate and you win.
-	 */
-	if (dp == NULL || dp->dad_ns_ocount == 0)
-		duplicate++;
-
-	/* XXX more checks for loopback situation - see nd6_dad_timer too */
 
-	if (duplicate) {
-		dp = NULL;	/* will be freed in nd6_dad_duplicated() */
-		nd6_dad_duplicated(ifa);
-	} else {
-		/*
-		 * not sure if I got a duplicate.
-		 * increment ns count and see what happens.
-		 */
-		if (dp)
-			dp->dad_ns_icount++;
-	}
+	dp->dad_ns_icount++;
+	nd6_dad_rele(dp);
 }
 
 static void
@@ -1564,10 +1556,9 @@ nd6_dad_na_input(struct ifaddr *ifa)
 	if (ifa == NULL)
 		panic("ifa == NULL in nd6_dad_na_input");
 
-	dp = nd6_dad_find(ifa);
-	if (dp)
+	dp = nd6_dad_find(ifa, NULL);
+	if (dp != NULL) {
 		dp->dad_na_icount++;
-
-	/* remove the address. */
-	nd6_dad_duplicated(ifa);
+		nd6_dad_rele(dp);
+	}
 }