/*      $FreeBSD: src/sys/netinet6/nd6.c,v 1.2.2.15 2003/05/06 06:46:58 suz Exp $       */
/*      $KAME: nd6.c,v 1.144 2001/05/24 07:44:00 itojun Exp $   */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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
 * 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)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/protosw.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/mutex.h>
#include <sys/resourcevar.h>

#include <sys/thread2.h>
#include <sys/mutex2.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/netisr2.h>
#include <net/netmsg2.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <netinet6/in6_var.h>
#include <netinet6/in6_ifattach.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet/icmp6.h>

#include <net/net_osdep.h>

#define ND6_SLOWTIMER_INTERVAL (60 * 60) /* 1 hour */
#define ND6_RECALC_REACHTM_INTERVAL (60 * 120) /* 2 hours */

#define SIN6(s) ((struct sockaddr_in6 *)s)
#define SDL(s) ((struct sockaddr_dl *)s)

/*
 * Determine if the route entry is a direct neighbor on the specified
 * interface.  The interface test is not done if ifp is passed as NULL.
 * The route entry is a neighbor if all of the following are true:
 *
 *      RTF_GATEWAY is FALSE
 *      LLINFO is TRUE
 *      rt_gateway family is AF_LINK
 *      rt_llinfo is non-NULL
 *      The interfaces matches (or ifp is passed as NULL)
 *
 *      NOTE: rt_llinfo can be NULL with LLINFO set, so both must be
 *            tested.
 *
 *      NOTE: We can't use rt->rt_ifp to check for the interface, since
 *            it may be the loopback interface if the entry is for our
 *            own address on a non-loopback interface.  Instead, we use
 *            rt->rt_ifa->ifa_ifp which should specify the REAL interface.
 */
#define ND6_IFP_MATCHES(ifp, ifa_ifp)                           \
        ((ifp) == NULL ||                                       \
         (ifa_ifp) == (ifp) ||                                  \
         (((ifp)->if_flags & IFF_ISBRIDGE) &&                   \
          (ifa_ifp)->if_bridge == (ifp)->if_softc)              \
        )

#define ND6_RTENTRY_IS_NEIGHBOR(rt, ifp)                        \
        (((rt)->rt_flags & RTF_GATEWAY) == 0 &&                 \
         ((rt)->rt_flags & RTF_LLINFO) != 0 &&                  \
         (rt)->rt_gateway->sa_family == AF_LINK &&              \
         (rt)->rt_llinfo &&                                     \
         ND6_IFP_MATCHES((ifp), (rt)->rt_ifa->ifa_ifp)          \
        )

#define ND6_RTENTRY_IS_LLCLONING(rt)                            \
        (((rt)->rt_flags & (RTF_PRCLONING | RTF_LLINFO)) ==     \
         (RTF_PRCLONING | RTF_LLINFO) ||                        \
         ((rt)->rt_flags & RTF_CLONING))

/* timer values */
int     nd6_prune       = 1;    /* walk list every 1 seconds */
int     nd6_delay       = 5;    /* delay first probe time 5 second */
int     nd6_umaxtries   = 3;    /* maximum unicast query */
int     nd6_mmaxtries   = 3;    /* maximum multicast query */
int     nd6_useloopback = 1;    /* use loopback interface for local traffic */
int     nd6_gctimer     = (60 * 60 * 24); /* 1 day: garbage collection timer */

/* preventing too many loops in ND option parsing */
int nd6_maxndopt = 10;  /* max # of ND options allowed */

int nd6_maxnudhint = 0; /* max # of subsequent upper layer hints */

#ifdef ND6_DEBUG
int nd6_debug = 1;
#else
int nd6_debug = 0;
#endif

/* for debugging? */
static int nd6_inuse, nd6_allocated;

struct llinfo_nd6 llinfo_nd6 = {&llinfo_nd6, &llinfo_nd6};
struct nd_drhead nd_defrouter;
struct nd_prhead nd_prefix = { 0 };
struct mtx nd6_mtx = MTX_INITIALIZER("nd6");

int nd6_recalc_reachtm_interval = ND6_RECALC_REACHTM_INTERVAL;
static struct sockaddr_in6 all1_sa;

static void nd6_setmtu0 (struct ifnet *, struct nd_ifinfo *);
static int regen_tmpaddr (struct in6_ifaddr *);
static void nd6_slowtimo(void *);
static void nd6_slowtimo_dispatch(netmsg_t);
static void nd6_timer(void *);
static void nd6_timer_dispatch(netmsg_t);

static struct callout nd6_slowtimo_ch;
static struct netmsg_base nd6_slowtimo_netmsg;

static struct callout nd6_timer_ch;
static struct netmsg_base nd6_timer_netmsg;

void
nd6_init(void)
{
        static int nd6_init_done = 0;
        int i;

        if (nd6_init_done) {
                log(LOG_NOTICE, "nd6_init called more than once(ignored)\n");
                return;
        }

        all1_sa.sin6_family = AF_INET6;
        all1_sa.sin6_len = sizeof(struct sockaddr_in6);
        for (i = 0; i < sizeof(all1_sa.sin6_addr); i++)
                all1_sa.sin6_addr.s6_addr[i] = 0xff;

        /* initialization of the default router list */
        TAILQ_INIT(&nd_defrouter);

        nd6_init_done = 1;

        /* start timer */
        callout_init_mp(&nd6_slowtimo_ch);
        netmsg_init(&nd6_slowtimo_netmsg, NULL, &netisr_adone_rport,
            MSGF_PRIORITY, nd6_slowtimo_dispatch);
        callout_reset_bycpu(&nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
            nd6_slowtimo, NULL, 0);
}

struct nd_ifinfo *
nd6_ifattach(struct ifnet *ifp)
{
        struct nd_ifinfo *nd;

        nd = kmalloc(sizeof(*nd), M_IP6NDP, M_WAITOK | M_ZERO);

        nd->initialized = 1;

        nd->chlim = IPV6_DEFHLIM;
        nd->basereachable = REACHABLE_TIME;
        nd->reachable = ND_COMPUTE_RTIME(nd->basereachable);
        nd->retrans = RETRANS_TIMER;

        nd->flags = ND6_IFF_PERFORMNUD;
        /* A loopback interface always has link-local address. */
        if (ip6_auto_linklocal || (ifp->if_flags & IFF_LOOPBACK))
                nd->flags |= ND6_IFF_AUTO_LINKLOCAL;
        /* A loopback interface does not need to accept RAs. */
        if (ip6_accept_rtadv && !(ifp->if_flags & IFF_LOOPBACK))
                nd->flags |= ND6_IFF_ACCEPT_RTADV;

        /* XXX: we cannot call nd6_setmtu since ifp is not fully initialized */
        nd6_setmtu0(ifp, nd);

        return nd;
}

void
nd6_ifdetach(struct nd_ifinfo *nd)
{
        kfree(nd, M_IP6NDP);
}

/*
 * Reset ND level link MTU. This function is called when the physical MTU
 * changes, which means we might have to adjust the ND level MTU.
 */
void
nd6_setmtu(struct ifnet *ifp)
{
        nd6_setmtu0(ifp, ND_IFINFO(ifp));
}

struct netmsg_nd6setmtu {
        struct netmsg_base      nmsg;
        struct ifnet            *ifp;
        struct nd_ifinfo        *ndi;
};

/* XXX todo: do not maintain copy of ifp->if_mtu in ndi->maxmtu */
static void
nd6_setmtu0_dispatch(netmsg_t msg)
{
        struct netmsg_nd6setmtu *nmsg = (struct netmsg_nd6setmtu *)msg;
        struct ifnet *ifp = nmsg->ifp;
        struct nd_ifinfo *ndi = nmsg->ndi;
        uint32_t omaxmtu;

        omaxmtu = ndi->maxmtu;

        switch (ifp->if_type) {
        case IFT_ETHER:
                ndi->maxmtu = MIN(ETHERMTU, ifp->if_mtu);
                break;
        case IFT_IEEE1394:      /* XXX should be IEEE1394MTU(1500) */
                ndi->maxmtu = MIN(ETHERMTU, ifp->if_mtu);
                break;
#ifdef IFT_IEEE80211
        case IFT_IEEE80211:     /* XXX should be IEEE80211MTU(1500) */
                ndi->maxmtu = MIN(ETHERMTU, ifp->if_mtu);
                break;
#endif
        default:
                ndi->maxmtu = ifp->if_mtu;
                break;
        }

        /*
         * Decreasing the interface MTU under IPV6 minimum MTU may cause
         * undesirable situation.  We thus notify the operator of the change
         * explicitly.  The check for omaxmtu is necessary to restrict the
         * log to the case of changing the MTU, not initializing it.
         */
        if (omaxmtu >= IPV6_MMTU && ndi->maxmtu < IPV6_MMTU) {
                log(LOG_NOTICE, "nd6_setmtu0: "
                    "new link MTU on %s (%lu) is too small for IPv6\n",
                    if_name(ifp), (unsigned long)ndi->maxmtu);
        }

        if (ndi->maxmtu > in6_maxmtu)
                in6_setmaxmtu(); /* check all interfaces just in case */

        lwkt_replymsg(&nmsg->nmsg.lmsg, 0);
}

void
nd6_setmtu0(struct ifnet *ifp, struct nd_ifinfo *ndi)
{
        struct netmsg_nd6setmtu nmsg;

        netmsg_init(&nmsg.nmsg, NULL, &curthread->td_msgport, 0,
            nd6_setmtu0_dispatch);
        nmsg.ifp = ifp;
        nmsg.ndi = ndi;
        lwkt_domsg(netisr_cpuport(0), &nmsg.nmsg.lmsg, 0);
}

void
nd6_option_init(void *opt, int icmp6len, union nd_opts *ndopts)
{
        bzero(ndopts, sizeof(*ndopts));
        ndopts->nd_opts_search = (struct nd_opt_hdr *)opt;
        ndopts->nd_opts_last
                = (struct nd_opt_hdr *)(((u_char *)opt) + icmp6len);

        if (icmp6len == 0) {
                ndopts->nd_opts_done = 1;
                ndopts->nd_opts_search = NULL;
        }
}

/*
 * Take one ND option.
 */
struct nd_opt_hdr *
nd6_option(union nd_opts *ndopts)
{
        struct nd_opt_hdr *nd_opt;
        int olen;

        if (!ndopts)
                panic("ndopts == NULL in nd6_option");
        if (!ndopts->nd_opts_last)
                panic("uninitialized ndopts in nd6_option");
        if (!ndopts->nd_opts_search)
                return NULL;
        if (ndopts->nd_opts_done)
                return NULL;

        nd_opt = ndopts->nd_opts_search;

        /* make sure nd_opt_len is inside the buffer */
        if ((caddr_t)&nd_opt->nd_opt_len >= (caddr_t)ndopts->nd_opts_last) {
                bzero(ndopts, sizeof(*ndopts));
                return NULL;
        }

        olen = nd_opt->nd_opt_len << 3;
        if (olen == 0) {
                /*
                 * Message validation requires that all included
                 * options have a length that is greater than zero.
                 */
                bzero(ndopts, sizeof(*ndopts));
                return NULL;
        }

        ndopts->nd_opts_search = (struct nd_opt_hdr *)((caddr_t)nd_opt + olen);
        if (ndopts->nd_opts_search > ndopts->nd_opts_last) {
                /* option overruns the end of buffer, invalid */
                bzero(ndopts, sizeof(*ndopts));
                return NULL;
        } else if (ndopts->nd_opts_search == ndopts->nd_opts_last) {
                /* reached the end of options chain */
                ndopts->nd_opts_done = 1;
                ndopts->nd_opts_search = NULL;
        }
        return nd_opt;
}

/*
 * Parse multiple ND options.
 * This function is much easier to use, for ND routines that do not need
 * multiple options of the same type.
 */
int
nd6_options(union nd_opts *ndopts)
{
        struct nd_opt_hdr *nd_opt;
        int i = 0;

        if (!ndopts)
                panic("ndopts == NULL in nd6_options");
        if (!ndopts->nd_opts_last)
                panic("uninitialized ndopts in nd6_options");
        if (!ndopts->nd_opts_search)
                return 0;

        while (1) {
                nd_opt = nd6_option(ndopts);
                if (!nd_opt && !ndopts->nd_opts_last) {
                        /*
                         * Message validation requires that all included
                         * options have a length that is greater than zero.
                         */
                        icmp6stat.icp6s_nd_badopt++;
                        bzero(ndopts, sizeof(*ndopts));
                        return -1;
                }

                if (!nd_opt)
                        goto skip1;

                switch (nd_opt->nd_opt_type) {
                case ND_OPT_SOURCE_LINKADDR:
                case ND_OPT_TARGET_LINKADDR:
                case ND_OPT_MTU:
                case ND_OPT_REDIRECTED_HEADER:
                        if (ndopts->nd_opt_array[nd_opt->nd_opt_type]) {
                                nd6log((LOG_INFO,
                                    "duplicated ND6 option found (type=%d)\n",
                                    nd_opt->nd_opt_type));
                                /* XXX bark? */
                        } else {
                                ndopts->nd_opt_array[nd_opt->nd_opt_type]
                                        = nd_opt;
                        }
                        break;
                case ND_OPT_PREFIX_INFORMATION:
                        if (ndopts->nd_opt_array[nd_opt->nd_opt_type] == 0) {
                                ndopts->nd_opt_array[nd_opt->nd_opt_type]
                                        = nd_opt;
                        }
                        ndopts->nd_opts_pi_end =
                                (struct nd_opt_prefix_info *)nd_opt;
                        break;
                default:
                        /*
                         * Unknown options must be silently ignored,
                         * to accomodate future extension to the protocol.
                         */
                        nd6log((LOG_DEBUG,
                            "nd6_options: unsupported option %d - "
                            "option ignored\n", nd_opt->nd_opt_type));
                }

skip1:
                i++;
                if (i > nd6_maxndopt) {
                        icmp6stat.icp6s_nd_toomanyopt++;
                        nd6log((LOG_INFO, "too many loop in nd opt\n"));
                        break;
                }

                if (ndopts->nd_opts_done)
                        break;
        }

        return 0;
}

/*
 * ND6 timer routine to expire default route list and prefix list
 */
static void
nd6_timer_dispatch(netmsg_t nmsg)
{
        struct llinfo_nd6 *ln;
        struct nd_defrouter *dr;
        struct nd_prefix *pr;
        struct ifnet *ifp;
        struct in6_ifaddr *ia6, *nia6;

        ASSERT_NETISR0;

        crit_enter();
        lwkt_replymsg(&nmsg->lmsg, 0);  /* reply ASAP */
        crit_exit();

        mtx_lock(&nd6_mtx);

        ln = llinfo_nd6.ln_next;
        while (ln && ln != &llinfo_nd6) {
                struct rtentry *rt;
                struct sockaddr_in6 *dst;
                struct llinfo_nd6 *next = ln->ln_next;
                /* XXX: used for the DELAY case only: */
                struct nd_ifinfo *ndi = NULL;

                if ((rt = ln->ln_rt) == NULL) {
                        ln = next;
                        continue;
                }
                if ((ifp = rt->rt_ifp) == NULL) {
                        ln = next;
                        continue;
                }
                ndi = ND_IFINFO(ifp);
                dst = (struct sockaddr_in6 *)rt_key(rt);

                if (ln->ln_expire > time_uptime) {
                        ln = next;
                        continue;
                }

                /* sanity check */
                if (!rt)
                        panic("rt=0 in nd6_timer(ln=%p)", ln);
                if (rt->rt_llinfo && (struct llinfo_nd6 *)rt->rt_llinfo != ln)
                        panic("rt_llinfo(%p) is not equal to ln(%p)",
                              rt->rt_llinfo, ln);
                if (!dst)
                        panic("dst=0 in nd6_timer(ln=%p)", ln);

                switch (ln->ln_state) {
                case ND6_LLINFO_WAITDELETE:
                        next = nd6_free(rt);
                        break;
                case ND6_LLINFO_INCOMPLETE:
                        if (ln->ln_asked++ >= nd6_mmaxtries) {
                                struct mbuf *m = ln->ln_hold;
                                if (m) {
                                        if (rt->rt_ifp) {
                                                /*
                                                 * Fake rcvif to make ICMP error
                                                 * more helpful in diagnosing
                                                 * for the receiver.
                                                 * XXX: should we consider
                                                 * older rcvif?
                                                 */
                                                m->m_pkthdr.rcvif = rt->rt_ifp;
                                        }

                                        /*
                                         * mbuf has empty MAC header, remove
                                         * for icmp.  XXX layer violation.
                                         */
                                        m_adj(m, ETHER_HDR_LEN);
                                        icmp6_error(m, ICMP6_DST_UNREACH,
                                                    ICMP6_DST_UNREACH_ADDR, 0);
                                        ln->ln_hold = NULL;
                                }
                                ln->ln_state = ND6_LLINFO_WAITDELETE;
                                rt_rtmsg(RTM_MISS, rt, rt->rt_ifp, 0);
                        }
                        ln->ln_expire = time_uptime +
                                ND_IFINFO(ifp)->retrans / 1000;
                        nd6_ns_output(ifp, NULL, &dst->sin6_addr,
                                ln, 0);
                        break;
                case ND6_LLINFO_REACHABLE:
                        if (ln->ln_expire) {
                                ln->ln_state = ND6_LLINFO_STALE;
                                ln->ln_expire = time_uptime + nd6_gctimer;
                        }
                        break;

                case ND6_LLINFO_STALE:
                        /* Garbage Collection(RFC 2461 5.3) */
                        if (ln->ln_expire)
                                next = nd6_free(rt);
                        break;

                case ND6_LLINFO_DELAY:
                        if (ndi && (ndi->flags & ND6_IFF_PERFORMNUD)) {
                                /* We need NUD */
                                ln->ln_asked = 1;
                                ln->ln_state = ND6_LLINFO_PROBE;
                                ln->ln_expire = time_uptime +
                                        ndi->retrans / 1000;
                                nd6_ns_output(ifp, &dst->sin6_addr,
                                              &dst->sin6_addr,
                                              ln, 0);
                        } else {
                                ln->ln_state = ND6_LLINFO_STALE; /* XXX */
                                ln->ln_expire = time_uptime + nd6_gctimer;
                        }
                        break;
                case ND6_LLINFO_PROBE:
                        if (ln->ln_asked < nd6_umaxtries) {
                                ln->ln_asked++;
                                ln->ln_expire = time_uptime +
                                        ND_IFINFO(ifp)->retrans / 1000;
                                nd6_ns_output(ifp, &dst->sin6_addr,
                                               &dst->sin6_addr, ln, 0);
                        } else {
                                rt_rtmsg(RTM_MISS, rt, rt->rt_ifp, 0);
                                next = nd6_free(rt);
                        }
                        break;
                }
                ln = next;
        }

        /* expire default router list */
        dr = TAILQ_FIRST(&nd_defrouter);
        while (dr) {
                if (dr->expire && dr->expire < time_uptime) {
                        struct nd_defrouter *t;
                        t = TAILQ_NEXT(dr, dr_entry);
                        defrtrlist_del(dr);
                        dr = t;
                } else {
                        dr = TAILQ_NEXT(dr, dr_entry);
                }
        }

        /*
         * expire interface addresses.
         * in the past the loop was inside prefix expiry processing.
         * However, from a stricter speci-confrmance standpoint, we should
         * rather separate address lifetimes and prefix lifetimes.
         */
addrloop:
        for (ia6 = in6_ifaddr; ia6; ia6 = nia6) {
                nia6 = ia6->ia_next;
                /* check address lifetime */
                if (IFA6_IS_INVALID(ia6)) {
                        int regen = 0;

                        /*
                         * If the expiring address is temporary, try
                         * regenerating a new one.  This would be useful when
                         * we suspended a laptop PC, then turned it on after a
                         * period that could invalidate all temporary
                         * addresses.  Although we may have to restart the
                         * loop (see below), it must be after purging the
                         * address.  Otherwise, we'd see an infinite loop of
                         * regeneration.
                         */
                        if (ip6_use_tempaddr &&
                            (ia6->ia6_flags & IN6_IFF_TEMPORARY)) {
                                if (regen_tmpaddr(ia6) == 0)
                                        regen = 1;
                        }

                        in6_purgeaddr(&ia6->ia_ifa);

                        if (regen)
                                goto addrloop; /* XXX: see below */
                        /* ia6 is no longer good, continue on to next */
                        continue;
                }
                if (IFA6_IS_DEPRECATED(ia6)) {
                        int oldflags = ia6->ia6_flags;

                        if ((oldflags & IN6_IFF_DEPRECATED) == 0) {
                                ia6->ia6_flags |= IN6_IFF_DEPRECATED;
                                in6_newaddrmsg((struct ifaddr *)ia6);
                        }

                        /*
                         * If a temporary address has just become deprecated,
                         * regenerate a new one if possible.
                         */
                        if (ip6_use_tempaddr &&
                            (ia6->ia6_flags & IN6_IFF_TEMPORARY) &&
                            !(oldflags & IN6_IFF_DEPRECATED)) {

                                if (regen_tmpaddr(ia6) == 0) {
                                        /*
                                         * A new temporary address is
                                         * generated.
                                         * XXX: this means the address chain
                                         * has changed while we are still in
                                         * the loop.  Although the change
                                         * would not cause disaster (because
                                         * it's not a deletion, but an
                                         * addition,) we'd rather restart the
                                         * loop just for safety.  Or does this
                                         * significantly reduce performance??
                                         */
                                        goto addrloop;
                                }
                        }
                } else {
                        /*
                         * A new RA might have made a deprecated address
                         * preferred.
                         */
                        if (ia6->ia6_flags & IN6_IFF_DEPRECATED) {
                                ia6->ia6_flags &= ~IN6_IFF_DEPRECATED;
                                in6_newaddrmsg((struct ifaddr *)ia6);
                        }
                }
        }

        /* expire prefix list */
        pr = nd_prefix.lh_first;
        while (pr) {
                /*
                 * check prefix lifetime.
                 * since pltime is just for autoconf, pltime processing for
                 * prefix is not necessary.
                 */
                if (pr->ndpr_expire && pr->ndpr_expire < time_uptime) {
                        struct nd_prefix *t;
                        t = pr->ndpr_next;

                        /*
                         * address expiration and prefix expiration are
                         * separate.  NEVER perform in6_purgeaddr here.
                         */

                        prelist_remove(pr);
                        pr = t;
                } else
                        pr = pr->ndpr_next;
        }

        mtx_unlock(&nd6_mtx);

        callout_reset(&nd6_timer_ch, nd6_prune * hz, nd6_timer, NULL);
}

static void
nd6_timer(void *arg __unused)
{
        struct lwkt_msg *lmsg = &nd6_timer_netmsg.lmsg;

        KASSERT(mycpuid == 0, ("not on cpu0"));
        crit_enter();
        if (lmsg->ms_flags & MSGF_DONE)
                lwkt_sendmsg_oncpu(netisr_cpuport(0), lmsg);
        crit_exit();
}

void
nd6_timer_init(void)
{
        callout_init_mp(&nd6_timer_ch);
        netmsg_init(&nd6_timer_netmsg, NULL, &netisr_adone_rport,
            MSGF_PRIORITY, nd6_timer_dispatch);
        callout_reset_bycpu(&nd6_timer_ch, hz, nd6_timer, NULL, 0);
}

static int
regen_tmpaddr(struct in6_ifaddr *ia6) /* deprecated/invalidated temporary
                                         address */
{
        struct ifaddr_container *ifac;
        struct ifnet *ifp;
        struct in6_ifaddr *public_ifa6 = NULL;

        ifp = ia6->ia_ifa.ifa_ifp;
        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;
                struct in6_ifaddr *it6;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                it6 = (struct in6_ifaddr *)ifa;

                /* ignore no autoconf addresses. */
                if (!(it6->ia6_flags & IN6_IFF_AUTOCONF))
                        continue;

                /* ignore autoconf addresses with different prefixes. */
                if (it6->ia6_ndpr == NULL || it6->ia6_ndpr != ia6->ia6_ndpr)
                        continue;

                /*
                 * Now we are looking at an autoconf address with the same
                 * prefix as ours.  If the address is temporary and is still
                 * preferred, do not create another one.  It would be rare, but
                 * could happen, for example, when we resume a laptop PC after
                 * a long period.
                 */
                if ((it6->ia6_flags & IN6_IFF_TEMPORARY) &&
                    !IFA6_IS_DEPRECATED(it6)) {
                        public_ifa6 = NULL;
                        break;
                }

                /*
                 * This is a public autoconf address that has the same prefix
                 * as ours.  If it is preferred, keep it.  We can't break the
                 * loop here, because there may be a still-preferred temporary
                 * address with the prefix.
                 */
                if (!IFA6_IS_DEPRECATED(it6))
                    public_ifa6 = it6;
        }

        if (public_ifa6 != NULL) {
                int e;

                if ((e = in6_tmpifadd(public_ifa6, 0)) != 0) {
                        log(LOG_NOTICE, "regen_tmpaddr: failed to create a new"
                            " tmp addr,errno=%d\n", e);
                        return (-1);
                }
                return (0);
        }

        return (-1);
}

/*
 * Nuke neighbor cache/prefix/default router management table, right before
 * ifp goes away.
 */
void
nd6_purge(struct ifnet *ifp)
{
        struct llinfo_nd6 *ln, *nln;
        struct nd_defrouter *dr, *ndr, drany;
        struct nd_prefix *pr, *npr;

        /* Nuke default router list entries toward ifp */
        if ((dr = TAILQ_FIRST(&nd_defrouter)) != NULL) {
                /*
                 * The first entry of the list may be stored in
                 * the routing table, so we'll delete it later.
                 */
                for (dr = TAILQ_NEXT(dr, dr_entry); dr; dr = ndr) {
                        ndr = TAILQ_NEXT(dr, dr_entry);
                        if (dr->ifp == ifp)
                                defrtrlist_del(dr);
                }
                dr = TAILQ_FIRST(&nd_defrouter);
                if (dr->ifp == ifp)
                        defrtrlist_del(dr);
        }

        /* Nuke prefix list entries toward ifp */
        for (pr = nd_prefix.lh_first; pr; pr = npr) {
                npr = pr->ndpr_next;
                if (pr->ndpr_ifp == ifp) {
                        /*
                         * Previously, pr->ndpr_addr is removed as well,
                         * but I strongly believe we don't have to do it.
                         * nd6_purge() is only called from in6_ifdetach(),
                         * which removes all the associated interface addresses
                         * by itself.
                         * (jinmei@kame.net 20010129)
                         */
                        prelist_remove(pr);
                }
        }

        /* cancel default outgoing interface setting */
        if (nd6_defifindex == ifp->if_index)
                nd6_setdefaultiface(0);

        if (!ip6_forwarding &&
            (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV)) {
                /* refresh default router list */
                bzero(&drany, sizeof(drany));
                defrouter_delreq(&drany, 0);
                defrouter_select();
        }

        /*
         * Nuke neighbor cache entries for the ifp.
         * Note that rt->rt_ifp may not be the same as ifp,
         * due to KAME goto ours hack.  See RTM_RESOLVE case in
         * nd6_rtrequest(), and ip6_input().
         */
        ln = llinfo_nd6.ln_next;
        while (ln && ln != &llinfo_nd6) {
                struct rtentry *rt;
                struct sockaddr_dl *sdl;

                nln = ln->ln_next;
                rt = ln->ln_rt;
                if (rt && rt->rt_gateway &&
                    rt->rt_gateway->sa_family == AF_LINK) {
                        sdl = (struct sockaddr_dl *)rt->rt_gateway;
                        if (sdl->sdl_index == ifp->if_index)
                                nln = nd6_free(rt);
                }
                ln = nln;
        }
}

struct rtentry *
nd6_lookup(struct in6_addr *addr6, int create, struct ifnet *ifp)
{
        struct rtentry *rt;
        struct sockaddr_in6 sin6;

        bzero(&sin6, sizeof(sin6));
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_addr = *addr6;

        if (create)
                rt = rtlookup((struct sockaddr *)&sin6);
        else
                rt = rtpurelookup((struct sockaddr *)&sin6);
        if (rt && !(rt->rt_flags & RTF_LLINFO)) {
                /*
                 * This is the case for the default route.
                 * If we want to create a neighbor cache for the address, we
                 * should free the route for the destination and allocate an
                 * interface route.
                 */
                if (create) {
                        --rt->rt_refcnt;
                        rt = NULL;
                }
        }
        if (!rt) {
                if (create && ifp) {
                        int e;

                        /*
                         * If no route is available and create is set,
                         * we allocate a host route for the destination
                         * and treat it like an interface route.
                         * This hack is necessary for a neighbor which can't
                         * be covered by our own prefix.
                         */
                        struct ifaddr *ifa;

                        ifa = ifaof_ifpforaddr((struct sockaddr *)&sin6, ifp);
                        if (ifa == NULL)
                                return (NULL);

                        /*
                         * Create a new route.  RTF_LLINFO is necessary
                         * to create a Neighbor Cache entry for the
                         * destination in nd6_rtrequest which will be
                         * called in rtrequest via ifa->ifa_rtrequest.
                         */
                        if ((e = rtrequest(RTM_ADD, (struct sockaddr *)&sin6,
                             ifa->ifa_addr, (struct sockaddr *)&all1_sa,
                             (ifa->ifa_flags | RTF_HOST | RTF_LLINFO) &
                             ~RTF_CLONING, &rt)) != 0) {
                                log(LOG_ERR,
                                    "nd6_lookup: failed to add route for a "
                                    "neighbor(%s), errno=%d\n",
                                    ip6_sprintf(addr6), e);
                        }
                        if (rt == NULL)
                                return (NULL);
                        if (rt->rt_llinfo) {
                                struct llinfo_nd6 *ln =
                                    (struct llinfo_nd6 *)rt->rt_llinfo;

                                ln->ln_state = ND6_LLINFO_NOSTATE;
                        }
                } else
                        return (NULL);
        }
        rt->rt_refcnt--;

        if (!ND6_RTENTRY_IS_NEIGHBOR(rt, ifp)) {
                if (create) {
                        log(LOG_DEBUG,
                            "nd6_lookup: failed to lookup %s (if = %s)\n",
                            ip6_sprintf(addr6), ifp ? if_name(ifp) : "unspec");
                        /* xxx more logs... kazu */
                }
                return (NULL);
        }
        return (rt);
}

static struct rtentry *
nd6_neighbor_lookup(struct in6_addr *addr6, struct ifnet *ifp)
{
        struct rtentry *rt;
        struct sockaddr_in6 sin6;

        bzero(&sin6, sizeof(sin6));
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_addr = *addr6;

        rt = rtpurelookup((struct sockaddr *)&sin6);
        if (rt == NULL)
                return (NULL);
        rt->rt_refcnt--;

        if (!ND6_RTENTRY_IS_NEIGHBOR(rt, ifp)) {
                if (nd6_onlink_ns_rfc4861 &&
                    (ND6_RTENTRY_IS_LLCLONING(rt) ||    /* not cloned yet */
                     (rt->rt_parent != NULL &&          /* cloning */
                      ND6_RTENTRY_IS_LLCLONING(rt->rt_parent)))) {
                        /*
                         * If cloning ever happened or is happening,
                         * rtentry for addr6 would or will become a
                         * neighbor cache.
                         */
                } else {
                        rt = NULL;
                }
        }
        return (rt);
}

/*
 * Detect if a given IPv6 address identifies a neighbor on a given link.
 * XXX: should take care of the destination of a p2p link?
 */
int
nd6_is_addr_neighbor(struct sockaddr_in6 *addr, struct ifnet *ifp)
{
        struct ifaddr_container *ifac;

#define IFADDR6(a) ((((struct in6_ifaddr *)(a))->ia_addr).sin6_addr)
#define IFMASK6(a) ((((struct in6_ifaddr *)(a))->ia_prefixmask).sin6_addr)

        /*
         * A link-local address is always a neighbor.
         * XXX: we should use the sin6_scope_id field rather than the embedded
         * interface index.
         */
        if (IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr) &&
            ntohs(*(u_int16_t *)&addr->sin6_addr.s6_addr[2]) == ifp->if_index)
                return (1);

        /*
         * If the address matches one of our addresses,
         * it should be a neighbor.
         */
        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                if (IN6_ARE_MASKED_ADDR_EQUAL(&IFADDR6(ifa), &addr->sin6_addr,
                    &IFMASK6(ifa)))
                        return (1);
        }

        /*
         * Even if the address matches none of our addresses, it might be
         * in the neighbor cache.
         */
        if (nd6_neighbor_lookup(&addr->sin6_addr, ifp) != NULL)
                return (1);

        return (0);
#undef IFADDR6
#undef IFMASK6
}

/*
 * Free an nd6 llinfo entry.
 */
struct llinfo_nd6 *
nd6_free(struct rtentry *rt)
{
        struct llinfo_nd6 *ln = (struct llinfo_nd6 *)rt->rt_llinfo, *next;
        struct in6_addr in6 = ((struct sockaddr_in6 *)rt_key(rt))->sin6_addr;
        struct nd_defrouter *dr;

        /*
         * we used to have kpfctlinput(PRC_HOSTDEAD) here.
         * even though it is not harmful, it was not really necessary.
         */

        /* XXX: this condition too restrictive? */
        if (!ip6_forwarding &&
            (ND_IFINFO(rt->rt_ifp)->flags & ND6_IFF_ACCEPT_RTADV)) {
                mtx_lock(&nd6_mtx);
                dr = defrouter_lookup(
                    &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr,
                    rt->rt_ifp);

                if (ln->ln_router || dr) {
                        /*
                         * rt6_flush must be called whether or not the neighbor
                         * is in the Default Router List.
                         * See a corresponding comment in nd6_na_input().
                         */
                        rt6_flush(&in6, rt->rt_ifp);
                }

                if (dr) {
                        /*
                         * Unreachablity of a router might affect the default
                         * router selection and on-link detection of advertised
                         * prefixes.
                         */

                        /*
                         * Temporarily fake the state to choose a new default
                         * router and to perform on-link determination of
                         * prefixes correctly.
                         * Below the state will be set correctly,
                         * or the entry itself will be deleted.
                         */
                        ln->ln_state = ND6_LLINFO_INCOMPLETE;

                        /*
                         * Since defrouter_select() does not affect the
                         * on-link determination and MIP6 needs the check
                         * before the default router selection, we perform
                         * the check now.
                         */
                        pfxlist_onlink_check();

                        if (dr == TAILQ_FIRST(&nd_defrouter)) {
                                /*
                                 * It is used as the current default router,
                                 * so we have to move it to the end of the
                                 * list and choose a new one.
                                 * XXX: it is not very efficient if this is
                                 *      the only router.
                                 */
                                TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
                                TAILQ_INSERT_TAIL(&nd_defrouter, dr, dr_entry);

                                defrouter_select();
                        }
                }
                mtx_unlock(&nd6_mtx);
        }

        /*
         * Before deleting the entry, remember the next entry as the
         * return value.  We need this because pfxlist_onlink_check() above
         * might have freed other entries (particularly the old next entry) as
         * a side effect (XXX).
         */
        next = ln->ln_next;

        /*
         * Detach the route from the routing tree and the list of neighbor
         * caches, and disable the route entry not to be used in already
         * cached routes.
         *
         * ND expiry happens under one big timer.
         * To avoid overflowing the route socket, don't report this.
         * Now that RTM_MISS is reported when an address is unresolvable
         * the benefit of reporting this deletion is questionable.
         */
        rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL);

        return (next);
}

/*
 * Upper-layer reachability hint for Neighbor Unreachability Detection.
 *
 * XXX cost-effective metods?
 */
void
nd6_nud_hint(struct rtentry *rt, struct in6_addr *dst6, int force)
{
        struct llinfo_nd6 *ln;

        /*
         * If the caller specified "rt", use that.  Otherwise, resolve the
         * routing table by supplied "dst6".
         */
        if (!rt) {
                if (!dst6)
                        return;
                if (!(rt = nd6_lookup(dst6, 0, NULL)))
                        return;
        }

        if ((rt->rt_flags & RTF_GATEWAY) ||
            !(rt->rt_flags & RTF_LLINFO) ||
            rt->rt_llinfo == NULL || rt->rt_gateway == NULL ||
            rt->rt_gateway->sa_family != AF_LINK) {
                /* This is not a host route. */
                return;
        }

        ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        if (ln->ln_state < ND6_LLINFO_REACHABLE)
                return;

        /*
         * if we get upper-layer reachability confirmation many times,
         * it is possible we have false information.
         */
        if (!force) {
                ln->ln_byhint++;
                if (ln->ln_byhint > nd6_maxnudhint)
                        return;
        }

        ln->ln_state = ND6_LLINFO_REACHABLE;
        if (ln->ln_expire)
                ln->ln_expire = time_uptime +
                        ND_IFINFO(rt->rt_ifp)->reachable;
}

void
nd6_rtrequest(int req, struct rtentry *rt)
{
        struct sockaddr *gate = rt->rt_gateway;
        struct llinfo_nd6 *ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
        struct ifnet *ifp = rt->rt_ifp;
        struct ifaddr *ifa;

        if ((rt->rt_flags & RTF_GATEWAY))
                return;

        if (nd6_need_cache(ifp) == 0 && !(rt->rt_flags & RTF_HOST)) {
                /*
                 * This is probably an interface direct route for a link
                 * which does not need neighbor caches (e.g. fe80::%lo0/64).
                 * We do not need special treatment below for such a route.
                 * Moreover, the RTF_LLINFO flag which would be set below
                 * would annoy the ndp(8) command.
                 */
                return;
        }

        if (req == RTM_RESOLVE &&
            (nd6_need_cache(ifp) == 0 || /* stf case */
             !nd6_is_addr_neighbor((struct sockaddr_in6 *)rt_key(rt), ifp))) {
                /*
                 * FreeBSD and BSD/OS often make a cloned host route based
                 * on a less-specific route (e.g. the default route).
                 * If the less specific route does not have a "gateway"
                 * (this is the case when the route just goes to a p2p or an
                 * stf interface), we'll mistakenly make a neighbor cache for
                 * the host route, and will see strange neighbor solicitation
                 * for the corresponding destination.  In order to avoid the
                 * confusion, we check if the destination of the route is
                 * a neighbor in terms of neighbor discovery, and stop the
                 * process if not.  Additionally, we remove the LLINFO flag
                 * so that ndp(8) will not try to get the neighbor information
                 * of the destination.
                 */
                rt->rt_flags &= ~RTF_LLINFO;
                return;
        }

        switch (req) {
        case RTM_ADD:
                /*
                 * There is no backward compatibility :)
                 *
                 * if (!(rt->rt_flags & RTF_HOST) &&
                 *     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
                 *         rt->rt_flags |= RTF_CLONING;
                 */
                if (rt->rt_flags & (RTF_CLONING | RTF_LLINFO)) {
                        /*
                         * Case 1: This route should come from
                         * a route to interface.  RTF_LLINFO flag is set
                         * for a host route whose destination should be
                         * treated as on-link.
                         */
                        rt_setgate(rt, rt_key(rt),
                                   (struct sockaddr *)&null_sdl);
                        gate = rt->rt_gateway;
                        SDL(gate)->sdl_type = ifp->if_type;
                        SDL(gate)->sdl_index = ifp->if_index;
                        if (ln)
                                ln->ln_expire = time_uptime;
                        if (ln && ln->ln_expire == 0) {
                                /* kludge for desktops */
                                ln->ln_expire = 1;
                        }
                        if ((rt->rt_flags & RTF_CLONING))
                                break;
                }
                /*
                 * In IPv4 code, we try to annonuce new RTF_ANNOUNCE entry here.
                 * We don't do that here since llinfo is not ready yet.
                 *
                 * There are also couple of other things to be discussed:
                 * - unsolicited NA code needs improvement beforehand
                 * - RFC2461 says we MAY send multicast unsolicited NA
                 *   (7.2.6 paragraph 4), however, it also says that we
                 *   SHOULD provide a mechanism to prevent multicast NA storm.
                 *   we don't have anything like it right now.
                 *   note that the mechanism needs a mutual agreement
                 *   between proxies, which means that we need to implement
                 *   a new protocol, or a new kludge.
                 * - from RFC2461 6.2.4, host MUST NOT send an unsolicited NA.
                 *   we need to check ip6forwarding before sending it.
                 *   (or should we allow proxy ND configuration only for
                 *   routers?  there's no mention about proxy ND from hosts)
                 */
#if 0
                /* XXX it does not work */
                if ((rt->rt_flags & RTF_ANNOUNCE) && mycpuid == 0) {
                        nd6_na_output(ifp,
                              &SIN6(rt_key(rt))->sin6_addr,
                              &SIN6(rt_key(rt))->sin6_addr,
                              ip6_forwarding ? ND_NA_FLAG_ROUTER : 0,
                              1, NULL);
                }
#endif
                /* FALLTHROUGH */
        case RTM_RESOLVE:
                if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) == 0) {
                        /*
                         * Address resolution isn't necessary for a point to
                         * point link, so we can skip this test for a p2p link.
                         */
                        if (gate->sa_family != AF_LINK ||
                            gate->sa_len < sizeof(null_sdl)) {
                                log(LOG_DEBUG,
                                    "nd6_rtrequest: bad gateway value: %s\n",
                                    if_name(ifp));
                                break;
                        }
                        SDL(gate)->sdl_type = ifp->if_type;
                        SDL(gate)->sdl_index = ifp->if_index;
                }
                if (ln != NULL)
                        break;  /* This happens on a route change */
                /*
                 * Case 2: This route may come from cloning, or a manual route
                 * add with a LL address.
                 */
                R_Malloc(ln, struct llinfo_nd6 *, sizeof(*ln));
                rt->rt_llinfo = (caddr_t)ln;
                if (!ln) {
                        log(LOG_DEBUG, "nd6_rtrequest: malloc failed\n");
                        break;
                }
                nd6_inuse++;
                nd6_allocated++;
                bzero(ln, sizeof(*ln));
                ln->ln_rt = rt;
                /* this is required for "ndp" command. - shin */
                if (req == RTM_ADD) {
                        /*
                         * gate should have some valid AF_LINK entry,
                         * and ln->ln_expire should have some lifetime
                         * which is specified by ndp command.
                         */
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
                } else {
                        /*
                         * When req == RTM_RESOLVE, rt is created and
                         * initialized in rtrequest(), so rt_expire is 0.
                         */
                        ln->ln_state = ND6_LLINFO_NOSTATE;
                        ln->ln_expire = time_uptime;
                }
                rt->rt_flags |= RTF_LLINFO;
                ln->ln_next = llinfo_nd6.ln_next;
                llinfo_nd6.ln_next = ln;
                ln->ln_prev = &llinfo_nd6;
                ln->ln_next->ln_prev = ln;

                /*
                 * check if rt_key(rt) is one of my address assigned
                 * to the interface.
                 */
                ifa = (struct ifaddr *)in6ifa_ifpwithaddr(rt->rt_ifp,
                    &SIN6(rt_key(rt))->sin6_addr);
                if (ifa) {
                        caddr_t macp = nd6_ifptomac(ifp);
                        ln->ln_expire = 0;
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
                        if (macp) {
                                bcopy(macp, LLADDR(SDL(gate)), ifp->if_addrlen);
                                SDL(gate)->sdl_alen = ifp->if_addrlen;
                        }
                        if (nd6_useloopback) {
                                rt->rt_ifp = loif;      /* XXX */
                                /*
                                 * Make sure rt_ifa be equal to the ifaddr
                                 * corresponding to the address.
                                 * We need this because when we refer
                                 * rt_ifa->ia6_flags in ip6_input, we assume
                                 * that the rt_ifa points to the address instead
                                 * of the loopback address.
                                 */
                                if (ifa != rt->rt_ifa) {
                                        IFAFREE(rt->rt_ifa);
                                        IFAREF(ifa);
                                        rt->rt_ifa = ifa;
                                }
                        }
                } else if (rt->rt_flags & RTF_ANNOUNCE) {
                        ln->ln_expire = 0;
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;

                        /*
                         * Join solicited node multicast for proxy ND, and only
                         * join it once on cpu0.
                         */
                        if ((ifp->if_flags & IFF_MULTICAST) && mycpuid == 0) {
                                struct in6_addr llsol;
                                int error;

                                llsol = SIN6(rt_key(rt))->sin6_addr;
                                llsol.s6_addr16[0] = htons(0xff02);
                                llsol.s6_addr16[1] = htons(ifp->if_index);
                                llsol.s6_addr32[1] = 0;
                                llsol.s6_addr32[2] = htonl(1);
                                llsol.s6_addr8[12] = 0xff;

                                if (!in6_addmulti(&llsol, ifp, &error)) {
                                        nd6log((LOG_ERR, "%s: failed to join "
                                            "%s (errno=%d)\n", if_name(ifp),
                                            ip6_sprintf(&llsol), error));
                                }
                        }
                }
                break;

        case RTM_DELETE:
                if (!ln)
                        break;
                /*
                 * Leave from solicited node multicast for proxy ND, and only
                 * leave it once on cpu0 (since we joined it once on cpu0).
                 */
                if ((rt->rt_flags & RTF_ANNOUNCE) &&
                    (ifp->if_flags & IFF_MULTICAST) && mycpuid == 0) {
                        struct in6_addr llsol;
                        struct in6_multi *in6m;

                        llsol = SIN6(rt_key(rt))->sin6_addr;
                        llsol.s6_addr16[0] = htons(0xff02);
                        llsol.s6_addr16[1] = htons(ifp->if_index);
                        llsol.s6_addr32[1] = 0;
                        llsol.s6_addr32[2] = htonl(1);
                        llsol.s6_addr8[12] = 0xff;

                        in6m = IN6_LOOKUP_MULTI(&llsol, ifp);
                        if (in6m)
                                in6_delmulti(in6m);
                }
                nd6_inuse--;
                ln->ln_next->ln_prev = ln->ln_prev;
                ln->ln_prev->ln_next = ln->ln_next;
                ln->ln_prev = NULL;
                rt->rt_llinfo = 0;
                rt->rt_flags &= ~RTF_LLINFO;
                if (ln->ln_hold)
                        m_freem(ln->ln_hold);
                R_Free(ln);
        }
}

int
nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
{
        struct in6_drlist *drl = (struct in6_drlist *)data;
        struct in6_prlist *prl = (struct in6_prlist *)data;
        struct in6_ndireq *ndi = (struct in6_ndireq *)data;
        struct in6_nbrinfo *nbi = (struct in6_nbrinfo *)data;
        struct in6_ndifreq *ndif = (struct in6_ndifreq *)data;
        struct nd_defrouter *dr, any;
        struct nd_prefix *pr;
        struct rtentry *rt;
        int i = 0, error = 0;

        switch (cmd) {
        case SIOCGDRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                bzero(drl, sizeof(*drl));
                mtx_lock(&nd6_mtx);
                dr = TAILQ_FIRST(&nd_defrouter);
                while (dr && i < DRLSTSIZ) {
                        drl->defrouter[i].rtaddr = dr->rtaddr;
                        if (IN6_IS_ADDR_LINKLOCAL(&drl->defrouter[i].rtaddr)) {
                                /* XXX: need to this hack for KAME stack */
                                drl->defrouter[i].rtaddr.s6_addr16[1] = 0;
                        } else
                                log(LOG_ERR,
                                    "default router list contains a "
                                    "non-linklocal address(%s)\n",
                                    ip6_sprintf(&drl->defrouter[i].rtaddr));

                        drl->defrouter[i].flags = dr->flags;
                        drl->defrouter[i].rtlifetime = dr->rtlifetime;
                        drl->defrouter[i].expire = dr->expire;
                        drl->defrouter[i].if_index = dr->ifp->if_index;
                        i++;
                        dr = TAILQ_NEXT(dr, dr_entry);
                }
                mtx_unlock(&nd6_mtx);
                break;
        case SIOCGPRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                /*
                 * XXX meaning of fields, especialy "raflags", is very
                 * differnet between RA prefix list and RR/static prefix list.
                 * how about separating ioctls into two?
                 */
                bzero(prl, sizeof(*prl));
                mtx_lock(&nd6_mtx);
                pr = nd_prefix.lh_first;
                while (pr && i < PRLSTSIZ) {
                        struct nd_pfxrouter *pfr;
                        int j;

                        in6_embedscope(&prl->prefix[i].prefix,
                            &pr->ndpr_prefix, NULL, NULL);
                        prl->prefix[i].raflags = pr->ndpr_raf;
                        prl->prefix[i].prefixlen = pr->ndpr_plen;
                        prl->prefix[i].vltime = pr->ndpr_vltime;
                        prl->prefix[i].pltime = pr->ndpr_pltime;
                        prl->prefix[i].if_index = pr->ndpr_ifp->if_index;
                        prl->prefix[i].expire = pr->ndpr_expire;

                        pfr = pr->ndpr_advrtrs.lh_first;
                        j = 0;
                        while (pfr) {
                                if (j < DRLSTSIZ) {
#define RTRADDR prl->prefix[i].advrtr[j]
                                        RTRADDR = pfr->router->rtaddr;
                                        if (IN6_IS_ADDR_LINKLOCAL(&RTRADDR)) {
                                                /* XXX: hack for KAME */
                                                RTRADDR.s6_addr16[1] = 0;
                                        } else
                                                log(LOG_ERR,
                                                    "a router(%s) advertises "
                                                    "a prefix with "
                                                    "non-link local address\n",
                                                    ip6_sprintf(&RTRADDR));
#undef RTRADDR
                                }
                                j++;
                                pfr = pfr->pfr_next;
                        }
                        prl->prefix[i].advrtrs = j;
                        prl->prefix[i].origin = PR_ORIG_RA;

                        i++;
                        pr = pr->ndpr_next;
                }
                mtx_unlock(&nd6_mtx);

                break;
        case OSIOCGIFINFO_IN6:
                /* XXX: old ndp(8) assumes a positive value for linkmtu. */
                bzero(&ndi->ndi, sizeof(ndi->ndi));
                ndi->ndi.linkmtu = IN6_LINKMTU(ifp);
                ndi->ndi.maxmtu = ND_IFINFO(ifp)->maxmtu;
                ndi->ndi.basereachable = ND_IFINFO(ifp)->basereachable;
                ndi->ndi.reachable = ND_IFINFO(ifp)->reachable;
                ndi->ndi.retrans = ND_IFINFO(ifp)->retrans;
                ndi->ndi.flags = ND_IFINFO(ifp)->flags;
                ndi->ndi.recalctm = ND_IFINFO(ifp)->recalctm;
                ndi->ndi.chlim = ND_IFINFO(ifp)->chlim;
                break;
        case SIOCGIFINFO_IN6:
                ndi->ndi = *ND_IFINFO(ifp);
                ndi->ndi.linkmtu = IN6_LINKMTU(ifp);
                break;
        case SIOCSIFINFO_IN6:
                /*
                 * used to change host variables from userland.
                 * intented for a use on router to reflect RA configurations.
                 */
                /* 0 means 'unspecified' */
                if (ndi->ndi.linkmtu != 0) {
                        if (ndi->ndi.linkmtu < IPV6_MMTU ||
                            ndi->ndi.linkmtu > IN6_LINKMTU(ifp)) {
                                error = EINVAL;
                                break;
                        }
                        ND_IFINFO(ifp)->linkmtu = ndi->ndi.linkmtu;
                }

                if (ndi->ndi.basereachable != 0) {
                        int obasereachable = ND_IFINFO(ifp)->basereachable;

                        ND_IFINFO(ifp)->basereachable = ndi->ndi.basereachable;
                        if (ndi->ndi.basereachable != obasereachable)
                                ND_IFINFO(ifp)->reachable =
                                    ND_COMPUTE_RTIME(ndi->ndi.basereachable);
                }
                if (ndi->ndi.retrans != 0)
                        ND_IFINFO(ifp)->retrans = ndi->ndi.retrans;
                if (ndi->ndi.chlim != 0)
                        ND_IFINFO(ifp)->chlim = ndi->ndi.chlim;
                /* FALLTHROUGH */
        case SIOCSIFINFO_FLAGS:
                if ((ndi->ndi.flags & ND6_IFF_AUTO_LINKLOCAL) &&
                    !(ND_IFINFO(ifp)->flags & ND6_IFF_AUTO_LINKLOCAL)) {
                        /* auto_linklocal 0->1 transision */
                        ND_IFINFO(ifp)->flags |= ND6_IFF_AUTO_LINKLOCAL;
                        in6_ifattach(ifp, NULL);
                }
                ND_IFINFO(ifp)->flags = ndi->ndi.flags;
                break;
        case SIOCSNDFLUSH_IN6:  /* XXX: the ioctl name is confusing... */
                /* flush default router list */
                /*
                 * xxx sumikawa: should not delete route if default
                 * route equals to the top of default router list
                 */
                bzero(&any, sizeof(any));
                defrouter_delreq(&any, 0);
                defrouter_select();
                /* xxx sumikawa: flush prefix list */
                break;
        case SIOCSPFXFLUSH_IN6:
        {
                /* flush all the prefix advertised by routers */
                struct nd_prefix *pr, *next;

                mtx_lock(&nd6_mtx);
                for (pr = nd_prefix.lh_first; pr; pr = next) {
                        struct in6_ifaddr *ia, *ia_next;

                        next = pr->ndpr_next;

                        if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
                                continue; /* XXX */

                        /* do we really have to remove addresses as well? */
                        for (ia = in6_ifaddr; ia; ia = ia_next) {
                                /* ia might be removed.  keep the next ptr. */
                                ia_next = ia->ia_next;

                                if (!(ia->ia6_flags & IN6_IFF_AUTOCONF))
                                        continue;

                                if (ia->ia6_ndpr == pr)
                                        in6_purgeaddr(&ia->ia_ifa);
                        }
                        prelist_remove(pr);
                }
                mtx_unlock(&nd6_mtx);
                break;
        }
        case SIOCSRTRFLUSH_IN6:
        {
                /* flush all the default routers */
                struct nd_defrouter *dr, *next;

                mtx_lock(&nd6_mtx);
                if ((dr = TAILQ_FIRST(&nd_defrouter)) != NULL) {
                        /*
                         * The first entry of the list may be stored in
                         * the routing table, so we'll delete it later.
                         */
                        for (dr = TAILQ_NEXT(dr, dr_entry); dr; dr = next) {
                                next = TAILQ_NEXT(dr, dr_entry);
                                defrtrlist_del(dr);
                        }
                        defrtrlist_del(TAILQ_FIRST(&nd_defrouter));
                }
                mtx_unlock(&nd6_mtx);
                break;
        }
        case SIOCGNBRINFO_IN6:
        {
                struct llinfo_nd6 *ln;
                struct in6_addr nb_addr = nbi->addr; /* make local for safety */

                /*
                 * XXX: KAME specific hack for scoped addresses
                 *      XXXX: for other scopes than link-local?
                 */
                if (IN6_IS_ADDR_LINKLOCAL(&nbi->addr) ||
                    IN6_IS_ADDR_MC_LINKLOCAL(&nbi->addr)) {
                        u_int16_t *idp = (u_int16_t *)&nb_addr.s6_addr[2];

                        if (*idp == 0)
                                *idp = htons(ifp->if_index);
                }

                mtx_lock(&nd6_mtx);
                if ((rt = nd6_lookup(&nb_addr, 0, ifp)) == NULL) {
                        error = EINVAL;
                        mtx_unlock(&nd6_mtx);
                        break;
                }
                ln = (struct llinfo_nd6 *)rt->rt_llinfo;
                nbi->state = ln->ln_state;
                nbi->asked = ln->ln_asked;
                nbi->isrouter = ln->ln_router;
                nbi->expire = ln->ln_expire;
                mtx_unlock(&nd6_mtx);

                break;
        }
        case SIOCGDEFIFACE_IN6: /* XXX: should be implemented as a sysctl? */
                ndif->ifindex = nd6_defifindex;
                break;
        case SIOCSDEFIFACE_IN6: /* XXX: should be implemented as a sysctl? */
                return (nd6_setdefaultiface(ndif->ifindex));
        }
        return (error);
}

/*
 * Create neighbor cache entry and cache link-layer address,
 * on reception of inbound ND6 packets.  (RS/RA/NS/redirect)
 */
struct rtentry *
nd6_cache_lladdr(struct ifnet *ifp, struct in6_addr *from, char *lladdr,
                 int lladdrlen,
                 int type,      /* ICMP6 type */
                 int code       /* type dependent information */)
{
        struct rtentry *rt = NULL;
        struct llinfo_nd6 *ln = NULL;
        int is_newentry;
        struct sockaddr_dl *sdl = NULL;
        int do_update;
        int olladdr;
        int llchange;
        int newstate = 0;

        if (!ifp)
                panic("ifp == NULL in nd6_cache_lladdr");
        if (!from)
                panic("from == NULL in nd6_cache_lladdr");

        /* nothing must be updated for unspecified address */
        if (IN6_IS_ADDR_UNSPECIFIED(from))
                return NULL;

        /*
         * Validation about ifp->if_addrlen and lladdrlen must be done in
         * the caller.
         *
         * XXX If the link does not have link-layer adderss, what should
         * we do? (ifp->if_addrlen == 0)
         * Spec says nothing in sections for RA, RS and NA.  There's small
         * description on it in NS section (RFC 2461 7.2.3).
         */

        rt = nd6_lookup(from, 0, ifp);
        if (!rt) {
#if 0
                /* nothing must be done if there's no lladdr */
                if (!lladdr || !lladdrlen)
                        return NULL;
#endif

                rt = nd6_lookup(from, 1, ifp);
                is_newentry = 1;
        } else {
                /* do nothing if static ndp is set */
                if (rt->rt_flags & RTF_STATIC)
                        return NULL;
                is_newentry = 0;
        }

        if (!rt)
                return NULL;
        if ((rt->rt_flags & (RTF_GATEWAY | RTF_LLINFO)) != RTF_LLINFO) {
fail:
                nd6_free(rt);
                return NULL;
        }
        ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        if (!ln)
                goto fail;
        if (!rt->rt_gateway)
                goto fail;
        if (rt->rt_gateway->sa_family != AF_LINK)
                goto fail;
        sdl = SDL(rt->rt_gateway);

        olladdr = (sdl->sdl_alen) ? 1 : 0;
        if (olladdr && lladdr) {
                if (bcmp(lladdr, LLADDR(sdl), ifp->if_addrlen))
                        llchange = 1;
                else
                        llchange = 0;
        } else
                llchange = 0;

        /*
         * newentry olladdr  lladdr  llchange   (*=record)
         *      0       n       n       --      (1)
         *      0       y       n       --      (2)
         *      0       n       y       --      (3) * STALE
         *      0       y       y       n       (4) *
         *      0       y       y       y       (5) * STALE
         *      1       --      n       --      (6)   NOSTATE(= PASSIVE)
         *      1       --      y       --      (7) * STALE
         */

        if (lladdr) {           /* (3-5) and (7) */
                /*
                 * Record source link-layer address
                 * XXX is it dependent to ifp->if_type?
                 */
                sdl->sdl_alen = ifp->if_addrlen;
                bcopy(lladdr, LLADDR(sdl), ifp->if_addrlen);
        }

        if (!is_newentry) {
                if ((!olladdr && lladdr) ||             /* (3) */
                    (olladdr && lladdr && llchange)) {  /* (5) */
                        do_update = 1;
                        newstate = ND6_LLINFO_STALE;
                } else {                                /* (1-2,4) */
                        do_update = 0;
                }
        } else {
                do_update = 1;
                if (!lladdr)                            /* (6) */
                        newstate = ND6_LLINFO_NOSTATE;
                else                                    /* (7) */
                        newstate = ND6_LLINFO_STALE;
        }

        if (do_update) {
                /*
                 * Update the state of the neighbor cache.
                 */
                ln->ln_state = newstate;

                if (ln->ln_state == ND6_LLINFO_STALE) {
                        /*
                         * XXX: since nd6_output() below will cause
                         * state tansition to DELAY and reset the timer,
                         * we must set the timer now, although it is actually
                         * meaningless.
                         */
                        ln->ln_expire = time_uptime + nd6_gctimer;

                        if (ln->ln_hold) {
                                /*
                                 * we assume ifp is not a p2p here, so just
                                 * set the 2nd argument as the 1st one.
                                 */
                                nd6_output(ifp, ifp, ln->ln_hold,
                                    (struct sockaddr_in6 *)rt_key(rt), rt);
                                ln->ln_hold = NULL;
                        }
                } else if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
                        /* probe right away */
                        ln->ln_expire = time_uptime;
                }
        }

        /*
         * ICMP6 type dependent behavior.
         *
         * NS: clear IsRouter if new entry
         * RS: clear IsRouter
         * RA: set IsRouter if there's lladdr
         * redir: clear IsRouter if new entry
         *
         * RA case, (1):
         * The spec says that we must set IsRouter in the following cases:
         * - If lladdr exist, set IsRouter.  This means (1-5).
         * - If it is old entry (!newentry), set IsRouter.  This means (7).
         * So, based on the spec, in (1-5) and (7) cases we must set IsRouter.
         * A quetion arises for (1) case.  (1) case has no lladdr in the
         * neighbor cache, this is similar to (6).
         * This case is rare but we figured that we MUST NOT set IsRouter.
         *
         * newentry olladdr  lladdr  llchange       NS  RS  RA  redir
         *                                                      D R
         *      0       n       n       --      (1)     c   ?     s
         *      0       y       n       --      (2)     c   s     s
         *      0       n       y       --      (3)     c   s     s
         *      0       y       y       n       (4)     c   s     s
         *      0       y       y       y       (5)     c   s     s
         *      1       --      n       --      (6) c   c       c s
         *      1       --      y       --      (7) c   c   s   c s
         *
         *                                      (c=clear s=set)
         */
        switch (type & 0xff) {
        case ND_NEIGHBOR_SOLICIT:
                /*
                 * New entry must have is_router flag cleared.
                 */
                if (is_newentry)        /* (6-7) */
                        ln->ln_router = 0;
                break;
        case ND_REDIRECT:
                /*
                 * If the icmp is a redirect to a better router, always set the
                 * is_router flag.  Otherwise, if the entry is newly created,
                 * clear the flag.  [RFC 2461, sec 8.3]
                 */
                if (code == ND_REDIRECT_ROUTER)
                        ln->ln_router = 1;
                else if (is_newentry) /* (6-7) */
                        ln->ln_router = 0;
                break;
        case ND_ROUTER_SOLICIT:
                /*
                 * is_router flag must always be cleared.
                 */
                ln->ln_router = 0;
                break;
        case ND_ROUTER_ADVERT:
                /*
                 * Mark an entry with lladdr as a router.
                 */
                if ((!is_newentry && (olladdr || lladdr)) ||    /* (2-5) */
                    (is_newentry && lladdr)) {                  /* (7) */
                        ln->ln_router = 1;
                }
                break;
        }

        if (llchange || lladdr)
                rt_rtmsg(llchange ? RTM_CHANGE : RTM_ADD, rt, rt->rt_ifp, 0);

        /*
         * When the link-layer address of a router changes, select the
         * best router again.  In particular, when the neighbor entry is newly
         * created, it might affect the selection policy.
         * Question: can we restrict the first condition to the "is_newentry"
         * case?
         * XXX: when we hear an RA from a new router with the link-layer
         * address option, defrouter_select() is called twice, since
         * defrtrlist_update called the function as well.  However, I believe
         * we can compromise the overhead, since it only happens the first
         * time.
         * XXX: although defrouter_select() should not have a bad effect
         * for those are not autoconfigured hosts, we explicitly avoid such
         * cases for safety.
         */
        if (do_update && ln->ln_router && !ip6_forwarding &&
            (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV))
                defrouter_select();

        return rt;
}

static void
nd6_slowtimo(void *arg __unused)
{
        struct lwkt_msg *lmsg = &nd6_slowtimo_netmsg.lmsg;

        KASSERT(mycpuid == 0, ("not on cpu0"));
        crit_enter();
        if (lmsg->ms_flags & MSGF_DONE)
                lwkt_sendmsg_oncpu(netisr_cpuport(0), lmsg);
        crit_exit();
}

static void
nd6_slowtimo_dispatch(netmsg_t nmsg)
{
        const struct ifnet_array *arr;
        struct nd_ifinfo *nd6if;
        int i;

        ASSERT_NETISR0;

        crit_enter();
        lwkt_replymsg(&nmsg->lmsg, 0);  /* reply ASAP */
        crit_exit();

        arr = ifnet_array_get();

        mtx_lock(&nd6_mtx);
        for (i = 0; i < arr->ifnet_count; ++i) {
                struct ifnet *ifp = arr->ifnet_arr[i];

                if (ifp->if_afdata[AF_INET6] == NULL)
                        continue;
                nd6if = ND_IFINFO(ifp);
                if (nd6if->basereachable && /* already initialized */
                    (nd6if->recalctm -= ND6_SLOWTIMER_INTERVAL) <= 0) {
                        /*
                         * Since reachable time rarely changes by router
                         * advertisements, we SHOULD insure that a new random
                         * value gets recomputed at least once every few hours.
                         * (RFC 2461, 6.3.4)
                         */
                        nd6if->recalctm = nd6_recalc_reachtm_interval;
                        nd6if->reachable = ND_COMPUTE_RTIME(nd6if->basereachable);
                }
        }
        mtx_unlock(&nd6_mtx);

        callout_reset(&nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
            nd6_slowtimo, NULL);
}

int
nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
           struct sockaddr_in6 *dst, struct rtentry *rt)
{
        int error;

        if (ifp->if_flags & IFF_LOOPBACK)
                error = ifp->if_output(origifp, m, (struct sockaddr *)dst, rt);
        else
                error = ifp->if_output(ifp, m, (struct sockaddr *)dst, rt);
        return error;
}

int
nd6_resolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
    struct sockaddr *dst0, u_char *desten)
{
        struct sockaddr_in6 *dst = SIN6(dst0);
        struct rtentry *rt = NULL;
        struct llinfo_nd6 *ln = NULL;
        int error;

        if (m->m_flags & M_MCAST) {
                switch (ifp->if_type) {
                case IFT_ETHER:
#ifdef IFT_L2VLAN
                case IFT_L2VLAN:
#endif
#ifdef IFT_IEEE80211
                case IFT_IEEE80211:
#endif
                        ETHER_MAP_IPV6_MULTICAST(&dst->sin6_addr,
                                                 desten);
                        return 0;
                case IFT_IEEE1394:
                        bcopy(ifp->if_broadcastaddr, desten, ifp->if_addrlen);
                        return 0;
                default:
                        error = EAFNOSUPPORT;
                        goto bad;
                }
        }

        if (rt0 != NULL) {
                error = rt_llroute(dst0, rt0, &rt);
                if (error != 0)
                        goto bad;
                ln = rt->rt_llinfo;
        }

        /*
         * Since nd6_is_addr_neighbor() internally calls nd6_lookup(),
         * the condition below is not very efficient.  But we believe
         * it is tolerable, because this should be a rare case.
         */
        if (ln == NULL && nd6_is_addr_neighbor(dst, ifp)) {
                rt = nd6_lookup(&dst->sin6_addr, 1, ifp);
                if (rt != NULL)
                        ln = rt->rt_llinfo;
        }

        if (ln == NULL || rt == NULL) {
                if (!(ifp->if_flags & IFF_POINTOPOINT) &&
                    !(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) {
                        log(LOG_DEBUG,
                            "nd6_output: can't allocate llinfo for %s "
                            "(ln=%p, rt=%p)\n",
                            ip6_sprintf(&dst->sin6_addr), ln, rt);
                        error = ENOBUFS;
                        goto bad;
                }
                return 0;
        }

        /* We don't have to do link-layer address resolution on a p2p link. */
        if ((ifp->if_flags & IFF_POINTOPOINT) &&
            ln->ln_state < ND6_LLINFO_REACHABLE) {
                ln->ln_state = ND6_LLINFO_STALE;
                ln->ln_expire = time_uptime + nd6_gctimer;
        }

        /*
         * The first time we send a packet to a neighbor whose entry is
         * STALE, we have to change the state to DELAY and a sets a timer to
         * expire in DELAY_FIRST_PROBE_TIME seconds to ensure do
         * neighbor unreachability detection on expiration.
         * (RFC 2461 7.3.3)
         */
        if (ln->ln_state == ND6_LLINFO_STALE) {
                ln->ln_asked = 0;
                ln->ln_state = ND6_LLINFO_DELAY;
                ln->ln_expire = time_uptime + nd6_delay;
        }

        /*
         * If the neighbor cache entry has a state other than INCOMPLETE
         * (i.e. its link-layer address is already resolved), return it.
         */
        if (ln->ln_state > ND6_LLINFO_INCOMPLETE) {
                struct sockaddr_dl *sdl = SDL(rt->rt_gateway);

                //KKASSERT(sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0);
                if (sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
                        bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
                        return 0;
                } else {
                        static struct krate krate_nce = { .freq = 1 };
                        krateprintf(&krate_nce,
                                    "nd6_resolve: incomplete neighbor cache "
                                    "ln=%p sdl=%p\n", ln, sdl);
                }
        }

        /*
         * There is a neighbor cache entry, but no ethernet address
         * response yet.  Replace the held mbuf (if any) with this
         * latest one.
         */
        if (ln->ln_hold)
                m_freem(ln->ln_hold);
        ln->ln_hold = m;

        /*
         * This code conforms to the rate-limiting rule described in Section
         * 7.2.2 of RFC 2461, because the timer is set correctly after sending
         * an NS below.
         */
        if (ln->ln_state == ND6_LLINFO_NOSTATE ||
            ln->ln_state == ND6_LLINFO_WAITDELETE) {
                /*
                 * This neighbor cache entry was just created; change its
                 * state to INCOMPLETE and start its life cycle.
                 *
                 * We force an NS output below by setting ln_expire to 1
                 * (nd6_rtrequest() could set it to the current time_uptime)
                 * and zeroing out ln_asked (XXX this may not be necessary).
                 */
                ln->ln_state = ND6_LLINFO_INCOMPLETE;
                ln->ln_expire = 1;
                ln->ln_asked = 0;
        }
        if (ln->ln_expire && ln->ln_expire < time_uptime && ln->ln_asked == 0) {
                ln->ln_asked++;
                ln->ln_expire = time_uptime + ND_IFINFO(ifp)->retrans / 1000;
                nd6_ns_output(ifp, NULL, &dst->sin6_addr, ln, 0);
        }

        if (ln->ln_asked >= nd6_mmaxtries)
                return (rt != NULL && rt->rt_flags & RTF_GATEWAY) ?
                    EHOSTUNREACH : EHOSTDOWN;
        return EWOULDBLOCK;

bad:
        m_freem(m);
        return error;
}

int
nd6_need_cache(struct ifnet *ifp)
{
        /*
         * XXX: we currently do not make neighbor cache on any interface
         * other than Ethernet and GIF.
         *
         * RFC2893 says:
         * - unidirectional tunnels needs no ND
         */
        switch (ifp->if_type) {
        case IFT_ETHER:
        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_GIF:           /* XXX need more cases? */
                return (1);
        default:
                return (0);
        }
}

static int nd6_sysctl_drlist(SYSCTL_HANDLER_ARGS);
static int nd6_sysctl_prlist(SYSCTL_HANDLER_ARGS);
#ifdef SYSCTL_DECL
SYSCTL_DECL(_net_inet6_icmp6);
#endif
SYSCTL_NODE(_net_inet6_icmp6, ICMPV6CTL_ND6_DRLIST, nd6_drlist,
        CTLFLAG_RD, nd6_sysctl_drlist, "List default routers");
SYSCTL_NODE(_net_inet6_icmp6, ICMPV6CTL_ND6_PRLIST, nd6_prlist,
        CTLFLAG_RD, nd6_sysctl_prlist, "List prefixes");

static int
nd6_sysctl_drlist(SYSCTL_HANDLER_ARGS)
{
        int error;
        char buf[1024];
        struct in6_defrouter *d, *de;
        struct nd_defrouter *dr;

        if (req->newptr)
                return EPERM;
        error = 0;

        for (dr = TAILQ_FIRST(&nd_defrouter); dr;
             dr = TAILQ_NEXT(dr, dr_entry)) {
                d = (struct in6_defrouter *)buf;
                de = (struct in6_defrouter *)(buf + sizeof(buf));

                if (d + 1 <= de) {
                        bzero(d, sizeof(*d));
                        d->rtaddr.sin6_family = AF_INET6;
                        d->rtaddr.sin6_len = sizeof(d->rtaddr);
                        if (in6_recoverscope(&d->rtaddr, &dr->rtaddr,
                            dr->ifp) != 0)
                                log(LOG_ERR,
                                    "scope error in "
                                    "default router list (%s)\n",
                                    ip6_sprintf(&dr->rtaddr));
                        d->flags = dr->flags;
                        d->rtlifetime = dr->rtlifetime;
                        d->expire = dr->expire;
                        d->if_index = dr->ifp->if_index;
                } else
                        panic("buffer too short");

                error = SYSCTL_OUT(req, buf, sizeof(*d));
                if (error)
                        break;
        }
        return error;
}

static int
nd6_sysctl_prlist(SYSCTL_HANDLER_ARGS)
{
        int error;
        char buf[1024];
        struct in6_prefix *p, *pe;
        struct nd_prefix *pr;

        if (req->newptr)
                return EPERM;
        error = 0;

        for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
                u_short advrtrs;
                size_t advance;
                struct sockaddr_in6 *sin6, *s6;
                struct nd_pfxrouter *pfr;

                p = (struct in6_prefix *)buf;
                pe = (struct in6_prefix *)(buf + sizeof(buf));

                if (p + 1 <= pe) {
                        bzero(p, sizeof(*p));
                        sin6 = (struct sockaddr_in6 *)(p + 1);

                        p->prefix = pr->ndpr_prefix;
                        if (in6_recoverscope(&p->prefix,
                            &p->prefix.sin6_addr, pr->ndpr_ifp) != 0)
                                log(LOG_ERR,
                                    "scope error in prefix list (%s)\n",
                                    ip6_sprintf(&p->prefix.sin6_addr));
                        p->raflags = pr->ndpr_raf;
                        p->prefixlen = pr->ndpr_plen;
                        p->vltime = pr->ndpr_vltime;
                        p->pltime = pr->ndpr_pltime;
                        p->if_index = pr->ndpr_ifp->if_index;
                        p->expire = pr->ndpr_expire;
                        p->refcnt = pr->ndpr_refcnt;
                        p->flags = pr->ndpr_stateflags;
                        p->origin = PR_ORIG_RA;
                        advrtrs = 0;
                        for (pfr = pr->ndpr_advrtrs.lh_first; pfr;
                             pfr = pfr->pfr_next) {
                                if ((void *)&sin6[advrtrs + 1] > (void *)pe) {
                                        advrtrs++;
                                        continue;
                                }
                                s6 = &sin6[advrtrs];
                                bzero(s6, sizeof(*s6));
                                s6->sin6_family = AF_INET6;
                                s6->sin6_len = sizeof(*sin6);
                                if (in6_recoverscope(s6, &pfr->router->rtaddr,
                                    pfr->router->ifp) != 0)
                                        log(LOG_ERR,
                                            "scope error in "
                                            "prefix list (%s)\n",
                                            ip6_sprintf(&pfr->router->rtaddr));
                                advrtrs++;
                        }
                        p->advrtrs = advrtrs;
                } else {
                        panic("buffer too short");
                }

                advance = sizeof(*p) + sizeof(*sin6) * advrtrs;
                error = SYSCTL_OUT(req, buf, advance);
                if (error)
                        break;
        }
        return error;
}