No empty .Rs/.Re

[netbsd-mini2440.git] / sys / netinet6 / nd6.c

/*      $NetBSD: nd6.c,v 1.134 2009/08/31 12:37:59 yamt Exp $   */
/*      $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.134 2009/08/31 12:37:59 yamt Exp $");

#include "opt_ipsec.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/socketvar.h>
#include <sys/sockio.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/protosw.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/syslog.h>
#include <sys/queue.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/if_ether.h>
#include <net/if_fddi.h>
#include <net/if_arc.h>

#include <netinet/in.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>
#include <netinet6/nd6.h>
#include <netinet/icmp6.h>
#include <netinet6/icmp6_private.h>

#ifdef IPSEC
#include <netinet6/ipsec.h>
#endif

#include <net/net_osdep.h>

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

/* 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 */

int nd6_maxqueuelen = 1; /* max # of packets cached in unresolved ND entries */

#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 = {
        .ln_prev = &llinfo_nd6,
        .ln_next = &llinfo_nd6,
};
struct nd_drhead nd_defrouter;
struct nd_prhead nd_prefix = { 0 };

int nd6_recalc_reachtm_interval = ND6_RECALC_REACHTM_INTERVAL;
static const struct sockaddr_in6 all1_sa = {
          .sin6_family = AF_INET6
        , .sin6_len = sizeof(struct sockaddr_in6)
        , .sin6_addr = {.s6_addr = {0xff, 0xff, 0xff, 0xff,
                                    0xff, 0xff, 0xff, 0xff,
                                    0xff, 0xff, 0xff, 0xff,
                                    0xff, 0xff, 0xff, 0xff}}
};

static void nd6_setmtu0(struct ifnet *, struct nd_ifinfo *);
static void nd6_slowtimo(void *);
static int regen_tmpaddr(struct in6_ifaddr *);
static struct llinfo_nd6 *nd6_free(struct rtentry *, int);
static void nd6_llinfo_timer(void *);
static void clear_llinfo_pqueue(struct llinfo_nd6 *);

callout_t nd6_slowtimo_ch;
callout_t nd6_timer_ch;
extern callout_t in6_tmpaddrtimer_ch;

static int fill_drlist(void *, size_t *, size_t);
static int fill_prlist(void *, size_t *, size_t);

MALLOC_DEFINE(M_IP6NDP, "NDP", "IPv6 Neighbour Discovery");

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

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

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

        nd6_init_done = 1;

        callout_init(&nd6_slowtimo_ch, CALLOUT_MPSAFE);
        callout_init(&nd6_timer_ch, CALLOUT_MPSAFE);

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

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

        nd = (struct nd_ifinfo *)malloc(sizeof(*nd), M_IP6NDP, M_WAITOK);
        memset(nd, 0, sizeof(*nd));

        nd->initialized = 1;

        nd->chlim = IPV6_DEFHLIM;
        nd->basereachable = REACHABLE_TIME;
        nd->reachable = ND_COMPUTE_RTIME(nd->basereachable);
        nd->retrans = RETRANS_TIMER;
        /*
         * Note that the default value of ip6_accept_rtadv is 0.
         * Because we do not set ND6_IFF_OVERRIDE_RTADV here, we won't
         * accept RAs by default.
         */
        nd->flags = ND6_IFF_PERFORMNUD | 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)
{

        free(nd, M_IP6NDP);
}

void
nd6_setmtu(struct ifnet *ifp)
{
        nd6_setmtu0(ifp, ND_IFINFO(ifp));
}

void
nd6_setmtu0(struct ifnet *ifp, struct nd_ifinfo *ndi)
{
        u_int32_t omaxmtu;

        omaxmtu = ndi->maxmtu;

        switch (ifp->if_type) {
        case IFT_ARCNET:
                ndi->maxmtu = MIN(ARC_PHDS_MAXMTU, ifp->if_mtu); /* RFC2497 */
                break;
        case IFT_FDDI:
                ndi->maxmtu = MIN(FDDIIPMTU, ifp->if_mtu);
                break;
        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 which needs %lu\n",
                    if_name(ifp), (unsigned long)ndi->maxmtu, (unsigned long)
                    IPV6_MMTU);
        }

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

void
nd6_option_init(void *opt, int icmp6len, union nd_opts *ndopts)
{

        memset(ndopts, 0, 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 == NULL)
                panic("ndopts == NULL in nd6_option");
        if (ndopts->nd_opts_last == NULL)
                panic("uninitialized ndopts in nd6_option");
        if (ndopts->nd_opts_search == NULL)
                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 ((void *)&nd_opt->nd_opt_len >= (void *)ndopts->nd_opts_last) {
                memset(ndopts, 0, 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.
                 */
                memset(ndopts, 0, sizeof(*ndopts));
                return NULL;
        }

        ndopts->nd_opts_search = (struct nd_opt_hdr *)((char *)nd_opt + olen);
        if (ndopts->nd_opts_search > ndopts->nd_opts_last) {
                /* option overruns the end of buffer, invalid */
                memset(ndopts, 0, 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 == NULL)
                panic("ndopts == NULL in nd6_options");
        if (ndopts->nd_opts_last == NULL)
                panic("uninitialized ndopts in nd6_options");
        if (ndopts->nd_opts_search == NULL)
                return 0;
 
        while (1) {
                nd_opt = nd6_option(ndopts);
                if (nd_opt == NULL && ndopts->nd_opts_last == NULL) {
                        /*
                         * Message validation requires that all included
                         * options have a length that is greater than zero.
                         */
                        ICMP6_STATINC(ICMP6_STAT_ND_BADOPT);
                        memset(ndopts, 0, sizeof(*ndopts));
                        return -1;
                }

                if (nd_opt == NULL)
                        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 accommodate 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) {
                        ICMP6_STATINC(ICMP6_STAT_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 handle ND6 entries
 */
void
nd6_llinfo_settimer(struct llinfo_nd6 *ln, long xtick)
{
        int s;

        s = splsoftnet();

        if (xtick < 0) {
                ln->ln_expire = 0;
                ln->ln_ntick = 0;
                callout_stop(&ln->ln_timer_ch);
        } else {
                ln->ln_expire = time_second + xtick / hz;
                if (xtick > INT_MAX) {
                        ln->ln_ntick = xtick - INT_MAX;
                        callout_reset(&ln->ln_timer_ch, INT_MAX,
                            nd6_llinfo_timer, ln);
                } else {
                        ln->ln_ntick = 0;
                        callout_reset(&ln->ln_timer_ch, xtick,
                            nd6_llinfo_timer, ln);
                }
        }

        splx(s);
}

static void
nd6_llinfo_timer(void *arg)
{
        struct llinfo_nd6 *ln;
        struct rtentry *rt;
        const struct sockaddr_in6 *dst;
        struct ifnet *ifp;
        struct nd_ifinfo *ndi = NULL;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        ln = (struct llinfo_nd6 *)arg;

        if (ln->ln_ntick > 0) {
                nd6_llinfo_settimer(ln, ln->ln_ntick);
                KERNEL_UNLOCK_ONE(NULL);
                mutex_exit(softnet_lock);
                return;
        }

        if ((rt = ln->ln_rt) == NULL)
                panic("ln->ln_rt == NULL");
        if ((ifp = rt->rt_ifp) == NULL)
                panic("ln->ln_rt->rt_ifp == NULL");
        ndi = ND_IFINFO(ifp);
        dst = satocsin6(rt_getkey(rt));

        /* sanity check */
        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_INCOMPLETE:
                if (ln->ln_asked < nd6_mmaxtries) {
                        ln->ln_asked++;
                        nd6_llinfo_settimer(ln, (long)ndi->retrans * hz / 1000);
                        nd6_ns_output(ifp, NULL, &dst->sin6_addr, ln, 0);
                } else {
                        struct mbuf *m = ln->ln_hold;
                        if (m) {
                                struct mbuf *m0;

                                /*
                                 * assuming every packet in ln_hold has
                                 * the same IP header
                                 */
                                m0 = m->m_nextpkt;
                                m->m_nextpkt = NULL;
                                icmp6_error2(m, ICMP6_DST_UNREACH,
                                    ICMP6_DST_UNREACH_ADDR, 0, rt->rt_ifp);

                                ln->ln_hold = m0;
                                clear_llinfo_pqueue(ln);
                        }
                        (void)nd6_free(rt, 0);
                        ln = NULL;
                }
                break;
        case ND6_LLINFO_REACHABLE:
                if (!ND6_LLINFO_PERMANENT(ln)) {
                        ln->ln_state = ND6_LLINFO_STALE;
                        nd6_llinfo_settimer(ln, (long)nd6_gctimer * hz);
                }
                break;

        case ND6_LLINFO_STALE:
                /* Garbage Collection(RFC 2461 5.3) */
                if (!ND6_LLINFO_PERMANENT(ln)) {
                        (void)nd6_free(rt, 1);
                        ln = NULL;
                }
                break;

        case ND6_LLINFO_DELAY:
                if (ndi && (ndi->flags & ND6_IFF_PERFORMNUD) != 0) {
                        /* We need NUD */
                        ln->ln_asked = 1;
                        ln->ln_state = ND6_LLINFO_PROBE;
                        nd6_llinfo_settimer(ln, (long)ndi->retrans * hz / 1000);
                        nd6_ns_output(ifp, &dst->sin6_addr,
                            &dst->sin6_addr, ln, 0);
                } else {
                        ln->ln_state = ND6_LLINFO_STALE; /* XXX */
                        nd6_llinfo_settimer(ln, (long)nd6_gctimer * hz);
                }
                break;
        case ND6_LLINFO_PROBE:
                if (ln->ln_asked < nd6_umaxtries) {
                        ln->ln_asked++;
                        nd6_llinfo_settimer(ln, (long)ndi->retrans * hz / 1000);
                        nd6_ns_output(ifp, &dst->sin6_addr,
                            &dst->sin6_addr, ln, 0);
                } else {
                        (void)nd6_free(rt, 0);
                        ln = NULL;
                }
                break;
        }

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * ND6 timer routine to expire default route list and prefix list
 */
void
nd6_timer(void *ignored_arg)
{
        struct nd_defrouter *next_dr, *dr;
        struct nd_prefix *next_pr, *pr;
        struct in6_ifaddr *ia6, *nia6;
        struct in6_addrlifetime *lt6;

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

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        /* expire default router list */
        
        for (dr = TAILQ_FIRST(&nd_defrouter); dr != NULL; dr = next_dr) {
                next_dr = TAILQ_NEXT(dr, dr_entry);
                if (dr->expire && dr->expire < time_second) {
                        defrtrlist_del(dr);
                }
        }

        /*
         * 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 */
                lt6 = &ia6->ia6_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) != 0) {
                                if (regen_tmpaddr(ia6) == 0)
                                        regen = 1;
                        }

                        in6_purgeaddr(&ia6->ia_ifa);

                        if (regen)
                                goto addrloop; /* XXX: see below */
                } else if (IFA6_IS_DEPRECATED(ia6)) {
                        int oldflags = ia6->ia6_flags;

                        ia6->ia6_flags |= IN6_IFF_DEPRECATED;

                        /*
                         * If a temporary address has just become deprecated,
                         * regenerate a new one if possible.
                         */
                        if (ip6_use_tempaddr &&
                            (ia6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                            (oldflags & IN6_IFF_DEPRECATED) == 0) {

                                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.
                         */
                        ia6->ia6_flags &= ~IN6_IFF_DEPRECATED;
                }
        }

        /* expire prefix list */
        for (pr = LIST_FIRST(&nd_prefix); pr != NULL; pr = next_pr) {
                next_pr = LIST_NEXT(pr, ndpr_entry);
                /*
                 * check prefix lifetime.
                 * since pltime is just for autoconf, pltime processing for
                 * prefix is not necessary.
                 */
                if (pr->ndpr_vltime != ND6_INFINITE_LIFETIME &&
                    time_second - pr->ndpr_lastupdate > pr->ndpr_vltime) {

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

                        prelist_remove(pr);
                }
        }

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

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

        ifp = ia6->ia_ifa.ifa_ifp;
        IFADDR_FOREACH(ifa, ifp) {
                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) == 0)
                        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) != 0 &&
                    !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;

                /*
                 * Random factor is introduced in the preferred lifetime, so
                 * we do not need additional delay (3rd arg to in6_tmpifadd).
                 */
                if ((e = in6_tmpifadd(public_ifa6, 0, 0)) != 0) {
                        log(LOG_NOTICE, "regen_tmpaddr: failed to create a new"
                            " tmp addr, errno=%d\n", e);
                        return -1;
                }
                return 0;
        }

        return -1;
}

bool
nd6_accepts_rtadv(const struct nd_ifinfo *ndi)
{
        switch (ndi->flags & (ND6_IFF_ACCEPT_RTADV|ND6_IFF_OVERRIDE_RTADV)) {
        case ND6_IFF_OVERRIDE_RTADV|ND6_IFF_ACCEPT_RTADV:
                return true;
        case ND6_IFF_ACCEPT_RTADV:
                return ip6_accept_rtadv != 0;
        case ND6_IFF_OVERRIDE_RTADV:
        case 0:
        default:
                return false;
        }
}

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

        /*
         * Nuke default router list entries toward ifp.
         * We defer removal of default router list entries that is installed
         * in the routing table, in order to keep additional side effects as
         * small as possible.
         */
        for (dr = TAILQ_FIRST(&nd_defrouter); dr != NULL; dr = ndr) {
                ndr = TAILQ_NEXT(dr, dr_entry);
                if (dr->installed)
                        continue;

                if (dr->ifp == ifp)
                        defrtrlist_del(dr);
        }
        for (dr = TAILQ_FIRST(&nd_defrouter); dr != NULL; dr = ndr) {
                ndr = TAILQ_NEXT(dr, dr_entry);
                if (!dr->installed)
                        continue;

                if (dr->ifp == ifp)
                        defrtrlist_del(dr);
        }

        /* Nuke prefix list entries toward ifp */
        for (pr = LIST_FIRST(&nd_prefix); pr != NULL; pr = npr) {
                npr = LIST_NEXT(pr, ndpr_entry);
                if (pr->ndpr_ifp == ifp) {
                        /*
                         * Because if_detach() does *not* release prefixes
                         * while purging addresses the reference count will
                         * still be above zero. We therefore reset it to
                         * make sure that the prefix really gets purged.
                         */
                        pr->ndpr_refcnt = 0;
                        /*
                         * 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);

        /* XXX: too restrictive? */
        if (!ip6_forwarding && ndi && nd6_accepts_rtadv(ndi)) {
                /* refresh default router list */
                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 != NULL && ln != &llinfo_nd6) {
                struct rtentry *rt;
                const 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 = satocsdl(rt->rt_gateway);
                        if (sdl->sdl_index == ifp->if_index)
                                nln = nd6_free(rt, 0);
                }
                ln = nln;
        }
}

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

        sockaddr_in6_init(&sin6, addr6, 0, 0, 0);
        rt = rtalloc1((struct sockaddr *)&sin6, create);
        if (rt != NULL && (rt->rt_flags & RTF_LLINFO) == 0) {
                /*
                 * 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) {
                        RTFREE(rt);
                        rt = NULL;
                }
        }
        if (rt != NULL)
                ;
        else 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 =
                    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, (const struct sockaddr *)&sin6,
                    ifa->ifa_addr, (const struct sockaddr *)&all1_sa,
                    (ifa->ifa_flags | RTF_HOST | RTF_LLINFO) &
                    ~RTF_CLONING, &rt)) != 0) {
#if 0
                        log(LOG_ERR,
                            "nd6_lookup: failed to add route for a "
                            "neighbor(%s), errno=%d\n",
                            ip6_sprintf(addr6), e);
#endif
                        return NULL;
                }
                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--;
        /*
         * Validation for the entry.
         * Note that the check for rt_llinfo is necessary because a cloned
         * route from a parent route that has the L flag (e.g. the default
         * route to a p2p interface) may have the flag, too, while the
         * destination is not actually a neighbor.
         * XXX: we can't use rt->rt_ifp to check for the interface, since
         *      it might be the loopback interface if the entry is for our
         *      own address on a non-loopback interface. Instead, we should
         *      use rt->rt_ifa->ifa_ifp, which would specify the REAL
         *      interface.
         * Note also that ifa_ifp and ifp may differ when we connect two
         * interfaces to a same link, install a link prefix to an interface,
         * and try to install a neighbor cache on an interface that does not
         * have a route to the prefix.
         */
        if ((rt->rt_flags & RTF_GATEWAY) || (rt->rt_flags & RTF_LLINFO) == 0 ||
            rt->rt_gateway->sa_family != AF_LINK || rt->rt_llinfo == NULL ||
            (ifp && rt->rt_ifa->ifa_ifp != ifp)) {
                if (create) {
                        nd6log((LOG_DEBUG,
                            "nd6_lookup: failed to lookup %s (if = %s)\n",
                            ip6_sprintf(addr6),
                            ifp ? if_name(ifp) : "unspec"));
                }
                return 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(const struct sockaddr_in6 *addr, struct ifnet *ifp)
{
        struct nd_prefix *pr;

        /*
         * A link-local address is always a neighbor.
         * XXX: a link does not necessarily specify a single interface.
         */
        if (IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr)) {
                struct sockaddr_in6 sin6_copy;
                u_int32_t zone;

                /*
                 * We need sin6_copy since sa6_recoverscope() may modify the
                 * content (XXX).
                 */
                sin6_copy = *addr;
                if (sa6_recoverscope(&sin6_copy))
                        return 0; /* XXX: should be impossible */
                if (in6_setscope(&sin6_copy.sin6_addr, ifp, &zone))
                        return 0;
                if (sin6_copy.sin6_scope_id == zone)
                        return 1;
                else
                        return 0;
        }

        /*
         * If the address matches one of our on-link prefixes, it should be a
         * neighbor.
         */
        LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
                if (pr->ndpr_ifp != ifp)
                        continue;

                if (!(pr->ndpr_stateflags & NDPRF_ONLINK))
                        continue;

                if (IN6_ARE_MASKED_ADDR_EQUAL(&pr->ndpr_prefix.sin6_addr,
                    &addr->sin6_addr, &pr->ndpr_mask))
                        return 1;
        }

        /*
         * If the default router list is empty, all addresses are regarded
         * as on-link, and thus, as a neighbor.
         * XXX: we restrict the condition to hosts, because routers usually do
         * not have the "default router list".
         */
        if (!ip6_forwarding && TAILQ_FIRST(&nd_defrouter) == NULL &&
            nd6_defifindex == ifp->if_index) {
                return 1;
        }

        /*
         * Even if the address matches none of our addresses, it might be
         * in the neighbor cache.
         */
        if (nd6_lookup(&addr->sin6_addr, 0, ifp) != NULL)
                return 1;

        return 0;
}

/*
 * Free an nd6 llinfo entry.
 * Since the function would cause significant changes in the kernel, DO NOT
 * make it global, unless you have a strong reason for the change, and are sure
 * that the change is safe.
 */
static struct llinfo_nd6 *
nd6_free(struct rtentry *rt, int gc)
{
        struct llinfo_nd6 *ln = (struct llinfo_nd6 *)rt->rt_llinfo, *next;
        struct in6_addr in6 = satocsin6(rt_getkey(rt))->sin6_addr;
        struct nd_defrouter *dr;

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

        /* cancel timer */
        nd6_llinfo_settimer(ln, -1);

        if (!ip6_forwarding) {
                int s;
                s = splsoftnet();
                dr = defrouter_lookup(&satocsin6(rt_getkey(rt))->sin6_addr,
                    rt->rt_ifp);

                if (dr != NULL && dr->expire &&
                    ln->ln_state == ND6_LLINFO_STALE && gc) {
                        /*
                         * If the reason for the deletion is just garbage
                         * collection, and the neighbor is an active default
                         * router, do not delete it.  Instead, reset the GC
                         * timer using the router's lifetime.
                         * Simply deleting the entry would affect default
                         * router selection, which is not necessarily a good
                         * thing, especially when we're using router preference
                         * values.
                         * XXX: the check for ln_state would be redundant,
                         *      but we intentionally keep it just in case.
                         */
                        if (dr->expire > time_second)
                                nd6_llinfo_settimer(ln,
                                    (dr->expire - time_second) * hz);
                        else
                                nd6_llinfo_settimer(ln, (long)nd6_gctimer * hz);
                        splx(s);
                        return ln->ln_next;
                }

                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();

                        /*
                         * refresh default router list
                         */
                        defrouter_select();
                }
                splx(s);
        }

        /*
         * 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.
         */
        rtrequest(RTM_DELETE, rt_getkey(rt), NULL, rt_mask(rt), 0, NULL);

        return next;
}

/*
 * Upper-layer reachability hint for Neighbor Unreachability Detection.
 *
 * XXX cost-effective methods?
 */
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 == NULL) {
                if (dst6 == NULL)
                        return;
                if ((rt = nd6_lookup(dst6, 0, NULL)) == NULL)
                        return;
        }

        if ((rt->rt_flags & RTF_GATEWAY) != 0 ||
            (rt->rt_flags & RTF_LLINFO) == 0 ||
            !rt->rt_llinfo || !rt->rt_gateway ||
            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 (!ND6_LLINFO_PERMANENT(ln)) {
                nd6_llinfo_settimer(ln,
                    (long)ND_IFINFO(rt->rt_ifp)->reachable * hz);
        }
}

void
nd6_rtrequest(int req, struct rtentry *rt, const struct rt_addrinfo *info)
{
        struct sockaddr *gate = rt->rt_gateway;
        struct llinfo_nd6 *ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        struct ifnet *ifp = rt->rt_ifp;
        uint8_t namelen = strlen(ifp->if_xname), addrlen = ifp->if_addrlen;
        struct ifaddr *ifa;

        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);

        if (req == RTM_LLINFO_UPD) {
                int rc;
                struct in6_addr *in6;
                struct in6_addr in6_all;
                int anycast;

                if ((ifa = info->rti_ifa) == NULL)
                        return;

                in6 = &ifatoia6(ifa)->ia_addr.sin6_addr;
                anycast = ifatoia6(ifa)->ia6_flags & IN6_IFF_ANYCAST;

                in6_all = in6addr_linklocal_allnodes;
                if ((rc = in6_setscope(&in6_all, ifa->ifa_ifp, NULL)) != 0) {
                        log(LOG_ERR, "%s: failed to set scope %s "
                            "(errno=%d)\n", __func__, if_name(ifp), rc);
                        return;
                }

                /* XXX don't set Override for proxy addresses */
                nd6_na_output(ifa->ifa_ifp, &in6_all, in6,
                    (anycast ? 0 : ND_NA_FLAG_OVERRIDE)
#if 0
                    | (ip6_forwarding ? ND_NA_FLAG_ROUTER : 0)
#endif
                    , 1, NULL);
                return;
        }

        if ((rt->rt_flags & RTF_GATEWAY) != 0)
                return;

        if (nd6_need_cache(ifp) == 0 && (rt->rt_flags & RTF_HOST) == 0) {
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * 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(satocsin6(rt_getkey(rt)), ifp))) {
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * 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:
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * There is no backward compatibility :)
                 *
                 * if ((rt->rt_flags & RTF_HOST) == 0 &&
                 *     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
                 *         rt->rt_flags |= RTF_CLONING;
                 */
                if ((rt->rt_flags & RTF_CLONING) ||
                    ((rt->rt_flags & RTF_LLINFO) && ln == NULL)) {
                        union {
                                struct sockaddr sa;
                                struct sockaddr_dl sdl;
                                struct sockaddr_storage ss;
                        } u;
                        /*
                         * Case 1: This route should come from a route to
                         * interface (RTF_CLONING case) or the route should be
                         * treated as on-link but is currently not
                         * (RTF_LLINFO && ln == NULL case).
                         */
                        sockaddr_dl_init(&u.sdl, sizeof(u.ss),
                            ifp->if_index, ifp->if_type,
                            NULL, namelen, NULL, addrlen);
                        rt_setgate(rt, &u.sa);
                        gate = rt->rt_gateway;
                        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                        if (ln != NULL)
                                nd6_llinfo_settimer(ln, 0);
                        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                        if ((rt->rt_flags & RTF_CLONING) != 0)
                                break;
                }
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * 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)
                        nd6_na_output(ifp,
                              &satocsin6(rt_getkey(rt))->sin6_addr,
                              &satocsin6(rt_getkey(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) {
                        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                        /*
                         * 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 <
                            sockaddr_dl_measure(namelen, addrlen)) {
                                log(LOG_DEBUG,
                                    "nd6_rtrequest: bad gateway value: %s\n",
                                    if_name(ifp));
                                break;
                        }
                        satosdl(gate)->sdl_type = ifp->if_type;
                        satosdl(gate)->sdl_index = ifp->if_index;
                        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                }
                if (ln != NULL)
                        break;  /* This happens on a route change */
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * 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 = ln;
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                if (ln == NULL) {
                        log(LOG_DEBUG, "nd6_rtrequest: malloc failed\n");
                        break;
                }
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                nd6_inuse++;
                nd6_allocated++;
                memset(ln, 0, sizeof(*ln));
                ln->ln_rt = rt;
                callout_init(&ln->ln_timer_ch, CALLOUT_MPSAFE);
                /* 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;
                        nd6_llinfo_settimer(ln, 0);
                }
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                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;

                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                /*
                 * check if rt_getkey(rt) is an address assigned
                 * to the interface.
                 */
                ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp,
                    &satocsin6(rt_getkey(rt))->sin6_addr);
                RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
                if (ifa != NULL) {
                        const void *mac;
                        nd6_llinfo_settimer(ln, -1);
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
                        if ((mac = nd6_ifptomac(ifp)) != NULL) {
                                /* XXX check for error */
                                (void)sockaddr_dl_setaddr(satosdl(gate),
                                    gate->sa_len, mac, ifp->if_addrlen);
                        }
                        if (nd6_useloopback) {
                                ifp = rt->rt_ifp = lo0ifp;      /* 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)
                                        rt_replace_ifa(rt, ifa);
                                rt->rt_flags &= ~RTF_CLONED;
                        }
                } else if (rt->rt_flags & RTF_ANNOUNCE) {
                        nd6_llinfo_settimer(ln, -1);
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;

                        /* join solicited node multicast for proxy ND */
                        if (ifp->if_flags & IFF_MULTICAST) {
                                struct in6_addr llsol;
                                int error;

                                llsol = satocsin6(rt_getkey(rt))->sin6_addr;
                                llsol.s6_addr32[0] = htonl(0xff020000);
                                llsol.s6_addr32[1] = 0;
                                llsol.s6_addr32[2] = htonl(1);
                                llsol.s6_addr8[12] = 0xff;
                                if (in6_setscope(&llsol, ifp, NULL))
                                        break;
                                if (!in6_addmulti(&llsol, ifp, &error, 0)) {
                                        nd6log((LOG_ERR, "%s: failed to join "
                                            "%s (errno=%d)\n", if_name(ifp),
                                            ip6_sprintf(&llsol), error));
                                }
                        }
                }
                break;

        case RTM_DELETE:
                if (ln == NULL)
                        break;
                /* leave from solicited node multicast for proxy ND */
                if ((rt->rt_flags & RTF_ANNOUNCE) != 0 &&
                    (ifp->if_flags & IFF_MULTICAST) != 0) {
                        struct in6_addr llsol;
                        struct in6_multi *in6m;

                        llsol = satocsin6(rt_getkey(rt))->sin6_addr;
                        llsol.s6_addr32[0] = htonl(0xff020000);
                        llsol.s6_addr32[1] = 0;
                        llsol.s6_addr32[2] = htonl(1);
                        llsol.s6_addr8[12] = 0xff;
                        if (in6_setscope(&llsol, ifp, NULL) == 0) {
                                IN6_LOOKUP_MULTI(llsol, ifp, in6m);
                                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;
                nd6_llinfo_settimer(ln, -1);
                rt->rt_llinfo = 0;
                rt->rt_flags &= ~RTF_LLINFO;
                clear_llinfo_pqueue(ln);
                Free(ln);
        }
}

int
nd6_ioctl(u_long cmd, void *data, struct ifnet *ifp)
{
        struct in6_drlist *drl = (struct in6_drlist *)data;
        struct in6_oprlist *oprl = (struct in6_oprlist *)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;
        struct nd_prefix *pr;
        struct rtentry *rt;
        int i = 0, error = 0;
        int s;

        switch (cmd) {
        case SIOCGDRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                memset(drl, 0, sizeof(*drl));
                s = splsoftnet();
                TAILQ_FOREACH(dr, &nd_defrouter, dr_entry) {
                        if (i >= DRLSTSIZ)
                                break;
                        drl->defrouter[i].rtaddr = dr->rtaddr;
                        in6_clearscope(&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++;
                }
                splx(s);
                break;
        case SIOCGPRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 *
                 * XXX the structure in6_prlist was changed in backward-
                 * incompatible manner.  in6_oprlist is used for SIOCGPRLST_IN6,
                 * in6_prlist is used for nd6_sysctl() - fill_prlist().
                 */
                /*
                 * XXX meaning of fields, especialy "raflags", is very
                 * differnet between RA prefix list and RR/static prefix list.
                 * how about separating ioctls into two?
                 */
                memset(oprl, 0, sizeof(*oprl));
                s = splsoftnet();
                LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
                        struct nd_pfxrouter *pfr;
                        int j;

                        if (i >= PRLSTSIZ)
                                break;
                        oprl->prefix[i].prefix = pr->ndpr_prefix.sin6_addr;
                        oprl->prefix[i].raflags = pr->ndpr_raf;
                        oprl->prefix[i].prefixlen = pr->ndpr_plen;
                        oprl->prefix[i].vltime = pr->ndpr_vltime;
                        oprl->prefix[i].pltime = pr->ndpr_pltime;
                        oprl->prefix[i].if_index = pr->ndpr_ifp->if_index;
                        if (pr->ndpr_vltime == ND6_INFINITE_LIFETIME)
                                oprl->prefix[i].expire = 0;
                        else {
                                time_t maxexpire;

                                /* XXX: we assume time_t is signed. */
                                maxexpire = (-1) &
                                    ~((time_t)1 <<
                                    ((sizeof(maxexpire) * 8) - 1));
                                if (pr->ndpr_vltime <
                                    maxexpire - pr->ndpr_lastupdate) {
                                        oprl->prefix[i].expire =
                                                 pr->ndpr_lastupdate +
                                                pr->ndpr_vltime;
                                } else
                                        oprl->prefix[i].expire = maxexpire;
                        }

                        j = 0;
                        LIST_FOREACH(pfr, &pr->ndpr_advrtrs, pfr_entry) {
                                if (j < DRLSTSIZ) {
#define RTRADDR oprl->prefix[i].advrtr[j]
                                        RTRADDR = pfr->router->rtaddr;
                                        in6_clearscope(&RTRADDR);
#undef RTRADDR
                                }
                                j++;
                        }
                        oprl->prefix[i].advrtrs = j;
                        oprl->prefix[i].origin = PR_ORIG_RA;

                        i++;
                }
                splx(s);

                break;
        case OSIOCGIFINFO_IN6:
#define ND      ndi->ndi
                /* XXX: old ndp(8) assumes a positive value for linkmtu. */
                memset(&ND, 0, sizeof(ND));
                ND.linkmtu = IN6_LINKMTU(ifp);
                ND.maxmtu = ND_IFINFO(ifp)->maxmtu;
                ND.basereachable = ND_IFINFO(ifp)->basereachable;
                ND.reachable = ND_IFINFO(ifp)->reachable;
                ND.retrans = ND_IFINFO(ifp)->retrans;
                ND.flags = ND_IFINFO(ifp)->flags;
                ND.recalctm = ND_IFINFO(ifp)->recalctm;
                ND.chlim = ND_IFINFO(ifp)->chlim;
                break;
        case SIOCGIFINFO_IN6:
                ND = *ND_IFINFO(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 (ND.linkmtu != 0) {
                        if (ND.linkmtu < IPV6_MMTU ||
                            ND.linkmtu > IN6_LINKMTU(ifp)) {
                                error = EINVAL;
                                break;
                        }
                        ND_IFINFO(ifp)->linkmtu = ND.linkmtu;
                }

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

                        ND_IFINFO(ifp)->basereachable = ND.basereachable;
                        if (ND.basereachable != obasereachable)
                                ND_IFINFO(ifp)->reachable =
                                    ND_COMPUTE_RTIME(ND.basereachable);
                }
                if (ND.retrans != 0)
                        ND_IFINFO(ifp)->retrans = ND.retrans;
                if (ND.chlim != 0)
                        ND_IFINFO(ifp)->chlim = ND.chlim;
                /* FALLTHROUGH */
        case SIOCSIFINFO_FLAGS:
                ND_IFINFO(ifp)->flags = ND.flags;
                break;
#undef ND
        case SIOCSNDFLUSH_IN6:  /* XXX: the ioctl name is confusing... */
                /* sync kernel routing table with the default router list */
                defrouter_reset();
                defrouter_select();
                break;
        case SIOCSPFXFLUSH_IN6:
        {
                /* flush all the prefix advertised by routers */
                struct nd_prefix *pfx, *next;

                s = splsoftnet();
                for (pfx = LIST_FIRST(&nd_prefix); pfx; pfx = next) {
                        struct in6_ifaddr *ia, *ia_next;

                        next = LIST_NEXT(pfx, ndpr_entry);

                        if (IN6_IS_ADDR_LINKLOCAL(&pfx->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) == 0)
                                        continue;

                                if (ia->ia6_ndpr == pfx)
                                        in6_purgeaddr(&ia->ia_ifa);
                        }
                        prelist_remove(pfx);
                }
                splx(s);
                break;
        }
        case SIOCSRTRFLUSH_IN6:
        {
                /* flush all the default routers */
                struct nd_defrouter *drtr, *next;

                s = splsoftnet();
                defrouter_reset();
                for (drtr = TAILQ_FIRST(&nd_defrouter); drtr; drtr = next) {
                        next = TAILQ_NEXT(drtr, dr_entry);
                        defrtrlist_del(drtr);
                }
                defrouter_select();
                splx(s);
                break;
        }
        case SIOCGNBRINFO_IN6:
        {
                struct llinfo_nd6 *ln;
                struct in6_addr nb_addr = nbi->addr; /* make local for safety */

                if ((error = in6_setscope(&nb_addr, ifp, NULL)) != 0)
                        return error;

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

                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;
}

void
nd6_llinfo_release_pkts(struct llinfo_nd6 *ln, struct ifnet *ifp,
    struct rtentry *rt)
{
        struct mbuf *m_hold, *m_hold_next;

        for (m_hold = ln->ln_hold, ln->ln_hold = NULL;
             m_hold != NULL;
             m_hold = m_hold_next) {
                m_hold_next = m_hold->m_nextpkt;
                m_hold->m_nextpkt = NULL;

                /*
                 * we assume ifp is not a p2p here, so
                 * just set the 2nd argument as the 
                 * 1st one.
                 */
                nd6_output(ifp, ifp, m_hold, satocsin6(rt_getkey(rt)), rt);
        }
}

/*
 * 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 nd_ifinfo *ndi = ND_IFINFO(ifp);
        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 == NULL)
                panic("ifp == NULL in nd6_cache_lladdr");
        if (from == NULL)
                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 == NULL) {
#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 == NULL)
                return NULL;
        if ((rt->rt_flags & (RTF_GATEWAY | RTF_LLINFO)) != RTF_LLINFO) {
fail:
                (void)nd6_free(rt, 0);
                return NULL;
        }
        ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        if (ln == NULL)
                goto fail;
        if (rt->rt_gateway == NULL)
                goto fail;
        if (rt->rt_gateway->sa_family != AF_LINK)
                goto fail;
        sdl = satosdl(rt->rt_gateway);

        olladdr = (sdl->sdl_alen) ? 1 : 0;
        if (olladdr && lladdr) {
                if (memcmp(lladdr, CLLADDR(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?
                 */
                /* XXX check for error */
                (void)sockaddr_dl_setaddr(sdl, sdl->sdl_len, lladdr,
                    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 == NULL)                     /* (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.
                         */
                        nd6_llinfo_settimer(ln, (long)nd6_gctimer * hz);

                        nd6_llinfo_release_pkts(ln, ifp, rt);
                } else if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
                        /* probe right away */
                        nd6_llinfo_settimer((void *)ln, 0);
                }
        }

        /*
         * 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;
        }

        /*
         * 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 &&
            nd6_accepts_rtadv(ndi))
                defrouter_select();

        return rt;
}

static void
nd6_slowtimo(void *ignored_arg)
{
        struct nd_ifinfo *nd6if;
        struct ifnet *ifp;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);
        callout_reset(&nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
            nd6_slowtimo, NULL);
        TAILQ_FOREACH(ifp, &ifnet, if_list) {
                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);
                }
        }
        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

#define senderr(e) { error = (e); goto bad;}
int
nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m0,
    const struct sockaddr_in6 *dst, struct rtentry *rt0)
{
        struct mbuf *m = m0;
        struct rtentry *rt = rt0;
        struct sockaddr_in6 *gw6 = NULL;
        struct llinfo_nd6 *ln = NULL;
        int error = 0;

        if (IN6_IS_ADDR_MULTICAST(&dst->sin6_addr))
                goto sendpkt;

        if (nd6_need_cache(ifp) == 0)
                goto sendpkt;

        /*
         * next hop determination.  This routine is derived from ether_output.
         */
        if (rt) {
                if ((rt->rt_flags & RTF_UP) == 0) {
                        if ((rt0 = rt = rtalloc1(sin6tocsa(dst), 1)) != NULL) {
                                rt->rt_refcnt--;
                                if (rt->rt_ifp != ifp)
                                        senderr(EHOSTUNREACH);
                        } else
                                senderr(EHOSTUNREACH);
                }

                if (rt->rt_flags & RTF_GATEWAY) {
                        gw6 = (struct sockaddr_in6 *)rt->rt_gateway;

                        /*
                         * We skip link-layer address resolution and NUD
                         * if the gateway is not a neighbor from ND point
                         * of view, regardless of the value of nd_ifinfo.flags.
                         * The second condition is a bit tricky; we skip
                         * if the gateway is our own address, which is
                         * sometimes used to install a route to a p2p link.
                         */
                        if (!nd6_is_addr_neighbor(gw6, ifp) ||
                            in6ifa_ifpwithaddr(ifp, &gw6->sin6_addr)) {
                                /*
                                 * We allow this kind of tricky route only
                                 * when the outgoing interface is p2p.
                                 * XXX: we may need a more generic rule here.
                                 */
                                if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                                        senderr(EHOSTUNREACH);

                                goto sendpkt;
                        }

                        if (rt->rt_gwroute == NULL)
                                goto lookup;
                        if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
                                rtfree(rt); rt = rt0;
                        lookup:
                                rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
                                if ((rt = rt->rt_gwroute) == NULL)
                                        senderr(EHOSTUNREACH);
                                /* the "G" test below also prevents rt == rt0 */
                                if ((rt->rt_flags & RTF_GATEWAY) ||
                                    (rt->rt_ifp != ifp)) {
                                        rt->rt_refcnt--;
                                        rt0->rt_gwroute = NULL;
                                        senderr(EHOSTUNREACH);
                                }
                        }
                }
        }

        /*
         * Address resolution or Neighbor Unreachability Detection
         * for the next hop.
         * At this point, the destination of the packet must be a unicast
         * or an anycast address(i.e. not a multicast).
         */

        /* Look up the neighbor cache for the nexthop */
        if (rt != NULL && (rt->rt_flags & RTF_LLINFO) != 0)
                ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        else {
                /*
                 * 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 (nd6_is_addr_neighbor(dst, ifp) &&
                    (rt = nd6_lookup(&dst->sin6_addr, 1, ifp)) != NULL)
                        ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        }
        if (ln == NULL || rt == NULL) {
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0 &&
                    !(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);
                        senderr(EIO);   /* XXX: good error? */
                }

                goto sendpkt;   /* send anyway */
        }

        /* We don't have to do link-layer address resolution on a p2p link. */
        if ((ifp->if_flags & IFF_POINTOPOINT) != 0 &&
            ln->ln_state < ND6_LLINFO_REACHABLE) {
                ln->ln_state = ND6_LLINFO_STALE;
                nd6_llinfo_settimer(ln, (long)nd6_gctimer * hz);
        }

        /*
         * 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;
                nd6_llinfo_settimer(ln, (long)nd6_delay * hz);
        }

        /*
         * If the neighbor cache entry has a state other than INCOMPLETE
         * (i.e. its link-layer address is already resolved), just
         * send the packet.
         */
        if (ln->ln_state > ND6_LLINFO_INCOMPLETE)
                goto sendpkt;

        /*
         * There is a neighbor cache entry, but no ethernet address
         * response yet.  Append this latest packet to the end of the
         * packet queue in the mbuf, unless the number of the packet
         * does not exceed nd6_maxqueuelen.  When it exceeds nd6_maxqueuelen,
         * the oldest packet in the queue will be removed.
         */
        if (ln->ln_state == ND6_LLINFO_NOSTATE)
                ln->ln_state = ND6_LLINFO_INCOMPLETE;
        if (ln->ln_hold) {
                struct mbuf *m_hold;
                int i;

                i = 0;
                for (m_hold = ln->ln_hold; m_hold; m_hold = m_hold->m_nextpkt) {
                        i++;
                        if (m_hold->m_nextpkt == NULL) {
                                m_hold->m_nextpkt = m;
                                break;
                        }
                }
                while (i >= nd6_maxqueuelen) {
                        m_hold = ln->ln_hold;
                        ln->ln_hold = ln->ln_hold->m_nextpkt;
                        m_freem(m_hold);
                        i--;
                }
        } else {
                ln->ln_hold = m;
        }

        /*
         * If there has been no NS for the neighbor after entering the
         * INCOMPLETE state, send the first solicitation.
         */
        if (!ND6_LLINFO_PERMANENT(ln) && ln->ln_asked == 0) {
                ln->ln_asked++;
                nd6_llinfo_settimer(ln,
                    (long)ND_IFINFO(ifp)->retrans * hz / 1000);
                nd6_ns_output(ifp, NULL, &dst->sin6_addr, ln, 0);
        }
        return 0;

  sendpkt:
        /* discard the packet if IPv6 operation is disabled on the interface */
        if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)) {
                error = ENETDOWN; /* better error? */
                goto bad;
        }

#ifdef IPSEC
        /* clean ipsec history once it goes out of the node */
        ipsec_delaux(m);
#endif
        if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                return (*ifp->if_output)(origifp, m, sin6tocsa(dst), rt);
        return (*ifp->if_output)(ifp, m, sin6tocsa(dst), rt);

  bad:
        if (m != NULL)
                m_freem(m);
        return error;
}
#undef senderr

int
nd6_need_cache(struct ifnet *ifp)
{
        /*
         * XXX: we currently do not make neighbor cache on any interface
         * other than ARCnet, Ethernet, FDDI and GIF.
         *
         * RFC2893 says:
         * - unidirectional tunnels needs no ND
         */
        switch (ifp->if_type) {
        case IFT_ARCNET:
        case IFT_ETHER:
        case IFT_FDDI:
        case IFT_IEEE1394:
        case IFT_CARP:
        case IFT_GIF:           /* XXX need more cases? */
        case IFT_PPP:
        case IFT_TUNNEL:
                return 1;
        default:
                return 0;
        }
}

int
nd6_storelladdr(const struct ifnet *ifp, const struct rtentry *rt,
    struct mbuf *m, const struct sockaddr *dst, uint8_t *lldst,
    size_t dstsize)
{
        const struct sockaddr_dl *sdl;

        if (m->m_flags & M_MCAST) {
                switch (ifp->if_type) {
                case IFT_ETHER:
                case IFT_FDDI:
                        ETHER_MAP_IPV6_MULTICAST(&satocsin6(dst)->sin6_addr,
                            lldst);
                        return 1;
                case IFT_IEEE1394:
                        memcpy(lldst, ifp->if_broadcastaddr,
                            MIN(dstsize, ifp->if_addrlen));
                        return 1;
                case IFT_ARCNET:
                        *lldst = 0;
                        return 1;
                default:
                        m_freem(m);
                        return 0;
                }
        }

        if (rt == NULL) {
                /* this could happen, if we could not allocate memory */
                m_freem(m);
                return 0;
        }
        if (rt->rt_gateway->sa_family != AF_LINK) {
                printf("%s: something odd happens\n", __func__);
                m_freem(m);
                return 0;
        }
        sdl = satocsdl(rt->rt_gateway);
        if (sdl->sdl_alen == 0 || sdl->sdl_alen > dstsize) {
                /* this should be impossible, but we bark here for debugging */
                printf("%s: sdl_alen == 0, dst=%s, if=%s\n", __func__,
                    ip6_sprintf(&satocsin6(dst)->sin6_addr), if_name(ifp));
                m_freem(m);
                return 0;
        }

        memcpy(lldst, CLLADDR(sdl), MIN(dstsize, sdl->sdl_alen));
        return 1;
}

static void 
clear_llinfo_pqueue(struct llinfo_nd6 *ln)
{
        struct mbuf *m_hold, *m_hold_next;

        for (m_hold = ln->ln_hold; m_hold; m_hold = m_hold_next) {
                m_hold_next = m_hold->m_nextpkt;
                m_hold->m_nextpkt = NULL;
                m_freem(m_hold);
        }

        ln->ln_hold = NULL;
        return;
}
 
int
nd6_sysctl(
    int name,
    void *oldp, /* syscall arg, need copyout */
    size_t *oldlenp,
    void *newp, /* syscall arg, need copyin */
    size_t newlen
)
{
        void *p;
        size_t ol;
        int error;

        error = 0;

        if (newp)
                return EPERM;
        if (oldp && !oldlenp)
                return EINVAL;
        ol = oldlenp ? *oldlenp : 0;

        if (oldp) {
                p = malloc(*oldlenp, M_TEMP, M_WAITOK);
                if (p == NULL)
                        return ENOMEM;
        } else
                p = NULL;
        switch (name) {
        case ICMPV6CTL_ND6_DRLIST:
                error = fill_drlist(p, oldlenp, ol);
                if (!error && p != NULL && oldp != NULL)
                        error = copyout(p, oldp, *oldlenp);
                break;

        case ICMPV6CTL_ND6_PRLIST:
                error = fill_prlist(p, oldlenp, ol);
                if (!error && p != NULL && oldp != NULL)
                        error = copyout(p, oldp, *oldlenp);
                break;

        case ICMPV6CTL_ND6_MAXQLEN:
                break;

        default:
                error = ENOPROTOOPT;
                break;
        }
        if (p)
                free(p, M_TEMP);

        return error;
}

static int
fill_drlist(void *oldp, size_t *oldlenp, size_t ol)
{
        int error = 0, s;
        struct in6_defrouter *d = NULL, *de = NULL;
        struct nd_defrouter *dr;
        size_t l;

        s = splsoftnet();

        if (oldp) {
                d = (struct in6_defrouter *)oldp;
                de = (struct in6_defrouter *)((char *)oldp + *oldlenp);
        }
        l = 0;

        TAILQ_FOREACH(dr, &nd_defrouter, dr_entry) {

                if (oldp && d + 1 <= de) {
                        memset(d, 0, sizeof(*d));
                        sockaddr_in6_init(&d->rtaddr, &dr->rtaddr, 0, 0, 0);
                        if (sa6_recoverscope(&d->rtaddr)) {
                                log(LOG_ERR,
                                    "scope error in router list (%s)\n",
                                    ip6_sprintf(&d->rtaddr.sin6_addr));
                                /* XXX: press on... */
                        }
                        d->flags = dr->flags;
                        d->rtlifetime = dr->rtlifetime;
                        d->expire = dr->expire;
                        d->if_index = dr->ifp->if_index;
                }

                l += sizeof(*d);
                if (d)
                        d++;
        }

        if (oldp) {
                if (l > ol)
                        error = ENOMEM;
        }
        if (oldlenp)
                *oldlenp = l;   /* (void *)d - (void *)oldp */

        splx(s);

        return error;
}

static int
fill_prlist(void *oldp, size_t *oldlenp, size_t ol)
{
        int error = 0, s;
        struct nd_prefix *pr;
        struct in6_prefix *p = NULL;
        struct in6_prefix *pe = NULL;
        size_t l;

        s = splsoftnet();

        if (oldp) {
                p = (struct in6_prefix *)oldp;
                pe = (struct in6_prefix *)((char *)oldp + *oldlenp);
        }
        l = 0;

        LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
                u_short advrtrs;
                size_t advance;
                struct sockaddr_in6 *sin6;
                struct sockaddr_in6 *s6;
                struct nd_pfxrouter *pfr;

                if (oldp && p + 1 <= pe)
                {
                        memset(p, 0, sizeof(*p));
                        sin6 = (struct sockaddr_in6 *)(p + 1);

                        p->prefix = pr->ndpr_prefix;
                        if (sa6_recoverscope(&p->prefix)) {
                                log(LOG_ERR,
                                    "scope error in prefix list (%s)\n",
                                    ip6_sprintf(&p->prefix.sin6_addr));
                                /* XXX: press on... */
                        }
                        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;
                        if (pr->ndpr_vltime == ND6_INFINITE_LIFETIME)
                                p->expire = 0;
                        else {
                                time_t maxexpire;

                                /* XXX: we assume time_t is signed. */
                                maxexpire = (-1) &
                                    ~((time_t)1 <<
                                    ((sizeof(maxexpire) * 8) - 1));
                                if (pr->ndpr_vltime <
                                    maxexpire - pr->ndpr_lastupdate) {
                                        p->expire = pr->ndpr_lastupdate +
                                                pr->ndpr_vltime;
                                } else
                                        p->expire = maxexpire;
                        }
                        p->refcnt = pr->ndpr_refcnt;
                        p->flags = pr->ndpr_stateflags;
                        p->origin = PR_ORIG_RA;
                        advrtrs = 0;
                        LIST_FOREACH(pfr, &pr->ndpr_advrtrs, pfr_entry) {
                                if ((void *)&sin6[advrtrs + 1] > (void *)pe) {
                                        advrtrs++;
                                        continue;
                                }
                                s6 = &sin6[advrtrs];
                                sockaddr_in6_init(s6, &pfr->router->rtaddr,
                                    0, 0, 0);
                                if (sa6_recoverscope(s6)) {
                                        log(LOG_ERR,
                                            "scope error in "
                                            "prefix list (%s)\n",
                                            ip6_sprintf(&pfr->router->rtaddr));
                                }
                                advrtrs++;
                        }
                        p->advrtrs = advrtrs;
                }
                else {
                        advrtrs = 0;
                        LIST_FOREACH(pfr, &pr->ndpr_advrtrs, pfr_entry)
                                advrtrs++;
                }

                advance = sizeof(*p) + sizeof(*sin6) * advrtrs;
                l += advance;
                if (p)
                        p = (struct in6_prefix *)((char *)p + advance);
        }

        if (oldp) {
                *oldlenp = l;   /* (void *)d - (void *)oldp */
                if (l > ol)
                        error = ENOMEM;
        } else
                *oldlenp = l;

        splx(s);

        return error;
}