xnu-1504.15.3.tar.gz

[apple/xnu.git] / bsd / netinet6 / nd6.c

/*
 * Copyright (c) 2008-2009 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*      $FreeBSD: src/sys/netinet6/nd6.c,v 1.20 2002/08/02 20:49:14 rwatson Exp $       */
/*      $KAME: nd6.c,v 1.144 2001/05/24 07:44:00 itojun Exp $   */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * XXX
 * KAME 970409 note:
 * BSD/OS version heavily modifies this code, related to llinfo.
 * Since we don't have BSD/OS version of net/route.c in our hand,
 * I left the code mostly as it was in 970310.  -- itojun
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/protosw.h>
#include <sys/proc.h>
#include <kern/queue.h>
#include <kern/zalloc.h>

#define DONT_WARN_OBSOLETE
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/if_atm.h>
#include <net/route.h>
#include <net/dlil.h>

#include <netinet/in.h>
#include <netinet/in_arp.h>
#include <netinet/if_ether.h>
#include <netinet/if_fddi.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_prefix.h>
#include <netinet/icmp6.h>

#include "loop.h"

#include <net/net_osdep.h>

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

#define SA(p) ((struct sockaddr *)(p))
#define SIN6(s) ((struct sockaddr_in6 *)s)
#define SDL(s) ((struct sockaddr_dl *)s)
#define equal(a1, a2) (bcmp((caddr_t)(a1), (caddr_t)(a2), (a1)->sa_len) == 0)

/* 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 */

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

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

/*
 * Synchronization notes:
 *
 * The global list of ND entries are stored in llinfo_nd6; an entry
 * gets inserted into the list when the route is created and gets
 * removed from the list when it is deleted; this is done as part
 * of RTM_ADD/RTM_RESOLVE/RTM_DELETE in nd6_rtrequest().
 *
 * Because rnh_lock and rt_lock for the entry are held during those
 * operations, the same locks (and thus lock ordering) must be used
 * elsewhere to access the relevant data structure fields:
 *
 * ln_next, ln_prev, ln_rt
 *
 *      - Routing lock (rnh_lock)
 *
 * ln_hold, ln_asked, ln_expire, ln_state, ln_router, ln_byhint, ln_flags
 *
 *      - Routing entry lock (rt_lock)
 *
 * Due to the dependency on rt_lock, llinfo_nd6 has the same lifetime
 * as the route entry itself.  When a route is deleted (RTM_DELETE),
 * it is simply removed from the global list but the memory is not
 * freed until the route itself is freed.
 */
struct llinfo_nd6 llinfo_nd6 = {
        &llinfo_nd6, &llinfo_nd6, NULL, NULL, 0, 0, 0, 0, 0, 0
};

/* Protected by nd_if_rwlock */
size_t nd_ifinfo_indexlim = 32; /* increased for 5589193 */
struct nd_ifinfo *nd_ifinfo = NULL;

static lck_grp_attr_t   *nd_if_rwlock_grp_attr;
static lck_grp_t        *nd_if_rwlock_grp;
static lck_attr_t       *nd_if_rwlock_attr;
lck_rw_t                *nd_if_rwlock;

/* Protected by nd6_mutex */
struct nd_drhead nd_defrouter;
struct nd_prhead nd_prefix = { 0 };

int nd6_recalc_reachtm_interval = ND6_RECALC_REACHTM_INTERVAL;
static struct sockaddr_in6 all1_sa;

static int regen_tmpaddr(struct in6_ifaddr *);
extern lck_mtx_t *ip6_mutex;
extern lck_mtx_t *nd6_mutex;

static void nd6_slowtimo(void *ignored_arg);
static struct llinfo_nd6 *nd6_llinfo_alloc(void);
static void nd6_llinfo_free(void *);

static void nd6_siocgdrlst(void *, int);
static void nd6_siocgprlst(void *, int);

/*
 * Insertion and removal from llinfo_nd6 must be done with rnh_lock held.
 */
#define LN_DEQUEUE(_ln) do {                                            \
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);                 \
        RT_LOCK_ASSERT_HELD((_ln)->ln_rt);                              \
        (_ln)->ln_next->ln_prev = (_ln)->ln_prev;                       \
        (_ln)->ln_prev->ln_next = (_ln)->ln_next;                       \
        (_ln)->ln_prev = (_ln)->ln_next = NULL;                         \
        (_ln)->ln_flags &= ~ND6_LNF_IN_USE;                             \
} while (0)

#define LN_INSERTHEAD(_ln) do {                                         \
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);                 \
        RT_LOCK_ASSERT_HELD((_ln)->ln_rt);                              \
        (_ln)->ln_next = llinfo_nd6.ln_next;                            \
        llinfo_nd6.ln_next = (_ln);                                     \
        (_ln)->ln_prev = &llinfo_nd6;                                   \
        (_ln)->ln_next->ln_prev = (_ln);                                \
        (_ln)->ln_flags |= ND6_LNF_IN_USE;                              \
} while (0)

static struct zone *llinfo_nd6_zone;
#define LLINFO_ND6_ZONE_MAX     256             /* maximum elements in zone */
#define LLINFO_ND6_ZONE_NAME    "llinfo_nd6"    /* name for zone */

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

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

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

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

        nd_if_rwlock_grp_attr = lck_grp_attr_alloc_init();
        nd_if_rwlock_grp = lck_grp_alloc_init("nd_if_rwlock",
            nd_if_rwlock_grp_attr);
        nd_if_rwlock_attr = lck_attr_alloc_init();
        nd_if_rwlock = lck_rw_alloc_init(nd_if_rwlock_grp, nd_if_rwlock_attr);

        llinfo_nd6_zone = zinit(sizeof (struct llinfo_nd6),
            LLINFO_ND6_ZONE_MAX * sizeof (struct llinfo_nd6), 0,
            LLINFO_ND6_ZONE_NAME);
        if (llinfo_nd6_zone == NULL)
                panic("%s: failed allocating llinfo_nd6_zone", __func__);

        zone_change(llinfo_nd6_zone, Z_EXPAND, TRUE);

        nd6_init_done = 1;

        /* start timer */
        timeout(nd6_slowtimo, (caddr_t)0, ND6_SLOWTIMER_INTERVAL * hz);
}

static struct llinfo_nd6 *
nd6_llinfo_alloc(void)
{
        return (zalloc(llinfo_nd6_zone));
}

static void
nd6_llinfo_free(void *arg)
{
        struct llinfo_nd6 *ln = arg;

        if (ln->ln_next != NULL || ln->ln_prev != NULL) {
                panic("%s: trying to free %p when it is in use", __func__, ln);
                /* NOTREACHED */
        }

        /* Just in case there's anything there, free it */
        if (ln->ln_hold != NULL) {
                m_freem(ln->ln_hold);
                ln->ln_hold = NULL;
        }

        zfree(llinfo_nd6_zone, ln);
}

int
nd6_ifattach(struct ifnet *ifp)
{

        /*
         * We have some arrays that should be indexed by if_index.
         * since if_index will grow dynamically, they should grow too.
         */
        lck_rw_lock_exclusive(nd_if_rwlock);
        if (nd_ifinfo == NULL || if_index >= nd_ifinfo_indexlim) {
                size_t n;
                caddr_t q;
                size_t newlim = nd_ifinfo_indexlim;

                while (if_index >= newlim)
                        newlim <<= 1;

                /* grow nd_ifinfo */
                n = newlim * sizeof(struct nd_ifinfo);
                q = (caddr_t)_MALLOC(n, M_IP6NDP, M_WAITOK);
                if (q == NULL) {
                        lck_rw_done(nd_if_rwlock);
                        return ENOBUFS;
                }
                bzero(q, n);
                nd_ifinfo_indexlim = newlim;
                if (nd_ifinfo) {
                        bcopy((caddr_t)nd_ifinfo, q, n/2);
                        /*
                         * We might want to pattern fill the old
                         * array to catch use-after-free cases.
                         */
                        FREE((caddr_t)nd_ifinfo, M_IP6NDP);
                }
                nd_ifinfo = (struct nd_ifinfo *)q;
        }
        lck_rw_done(nd_if_rwlock);

#define ND nd_ifinfo[ifp->if_index]

        /*
         * Don't initialize if called twice.
         * XXX: to detect this, we should choose a member that is never set
         * before initialization of the ND structure itself.  We formaly used
         * the linkmtu member, which was not suitable because it could be 
         * initialized via "ifconfig mtu".
         */
        lck_rw_lock_shared(nd_if_rwlock);
        if (ND.basereachable) {
                lck_rw_done(nd_if_rwlock);
                return 0;
        }
        ND.linkmtu = ifp->if_mtu;
        ND.chlim = IPV6_DEFHLIM;
        ND.basereachable = REACHABLE_TIME;
        ND.reachable = ND_COMPUTE_RTIME(ND.basereachable);
        ND.retrans = RETRANS_TIMER;
        ND.receivedra = 0;
        ND.flags = ND6_IFF_PERFORMNUD;
        lck_rw_done(nd_if_rwlock);
        nd6_setmtu(ifp);
#undef ND
        
        return 0;
}

/*
 * Reset ND level link MTU. This function is called when the physical MTU
 * changes, which means we might have to adjust the ND level MTU.
 */
void
nd6_setmtu(struct ifnet *ifp)
{
        struct nd_ifinfo *ndi;
        u_int32_t oldmaxmtu, maxmtu;

        /*
         * Make sure IPv6 is enabled for the interface first, 
         * because this can be called directly from SIOCSIFMTU for IPv4
         */
        lck_rw_lock_shared(nd_if_rwlock);
        if (ifp->if_index >= nd_ifinfo_indexlim) {
                lck_rw_done(nd_if_rwlock);
                return; /* we're  out of bound for nd_ifinfo */
        }

        ndi = &nd_ifinfo[ifp->if_index];
        oldmaxmtu = ndi->maxmtu;

        /*
         * The ND level maxmtu is somewhat redundant to the interface MTU
         * and is an implementation artifact of KAME.  Instead of hard-
         * limiting the maxmtu based on the interface type here, we simply
         * take the if_mtu value since SIOCSIFMTU would have taken care of
         * the sanity checks related to the maximum MTU allowed for the
         * interface (a value that is known only by the interface layer),
         * by sending the request down via ifnet_ioctl().  The use of the
         * ND level maxmtu and linkmtu (the latter obtained via RA) are done
         * via IN6_LINKMTU() which does further checking against if_mtu.
         */
        maxmtu = ndi->maxmtu = ifp->if_mtu;

        /*
        * Decreasing the interface MTU under IPV6 minimum MTU may cause
        * undesirable situation.  We thus notify the operator of the change
        * explicitly.  The check for oldmaxmtu is necessary to restrict the
        * log to the case of changing the MTU, not initializing it.
        */
        if (oldmaxmtu >= IPV6_MMTU && ndi->maxmtu < IPV6_MMTU) {
                log(LOG_NOTICE, "nd6_setmtu: "
                    "new link MTU on %s%d (%u) is too small for IPv6\n",
                    ifp->if_name, ifp->if_unit, (uint32_t)ndi->maxmtu);
        }
        lck_rw_done(nd_if_rwlock);

        /* also adjust in6_maxmtu if necessary. */
        if (maxmtu > in6_maxmtu)
                in6_setmaxmtu();
}

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

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

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

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

        nd_opt = ndopts->nd_opts_search;

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

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

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

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

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

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

                if (!nd_opt)
                        goto skip1;

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

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

                if (ndopts->nd_opts_done)
                        break;
        }

        return 0;
}

void
nd6_drain(__unused void *ignored_arg)
{
        struct llinfo_nd6 *ln;
        struct nd_defrouter *dr;
        struct nd_prefix *pr;
        struct ifnet *ifp = NULL;
        struct in6_ifaddr *ia6, *nia6;
        struct in6_addrlifetime *lt6;
        struct timeval timenow;

        getmicrotime(&timenow);
again:
        /*
         * The global list llinfo_nd6 is modified by nd6_request() and is
         * therefore protected by rnh_lock.  For obvious reasons, we cannot
         * hold rnh_lock across calls that might lead to code paths which
         * attempt to acquire rnh_lock, else we deadlock.  Hence for such
         * cases we drop rt_lock and rnh_lock, make the calls, and repeat the
         * loop.  To ensure that we don't process the same entry more than
         * once in a single timeout, we mark the "already-seen" entries with
         * ND6_LNF_TIMER_SKIP flag.  At the end of the loop, we do a second
         * pass thru the entries and clear the flag so they can be processed
         * during the next timeout.
         */
        lck_mtx_lock(rnh_lock);
        ln = llinfo_nd6.ln_next;
        while (ln != NULL && ln != &llinfo_nd6) {
                struct rtentry *rt;
                struct sockaddr_in6 *dst;
                struct llinfo_nd6 *next;
                struct nd_ifinfo ndi;

                /* ln_next/prev/rt is protected by rnh_lock */
                next = ln->ln_next;
                rt = ln->ln_rt;
                RT_LOCK(rt);

                /* We've seen this already; skip it */
                if (ln->ln_flags & ND6_LNF_TIMER_SKIP) {
                        RT_UNLOCK(rt);
                        ln = next;
                        continue;
                }

                /* rt->rt_ifp should never be NULL */
                if ((ifp = rt->rt_ifp) == NULL) {
                        panic("%s: ln(%p) rt(%p) rt_ifp == NULL", __func__,
                            ln, rt);
                        /* NOTREACHED */
                }

                /* rt_llinfo must always be equal to ln */
                if ((struct llinfo_nd6 *)rt->rt_llinfo != ln) {
                        panic("%s: rt_llinfo(%p) is not equal to ln(%p)",
                              __func__, rt->rt_llinfo, ln);
                        /* NOTREACHED */
                }

                /* rt_key should never be NULL */
                dst = (struct sockaddr_in6 *)rt_key(rt);
                if (dst == NULL) {
                        panic("%s: rt(%p) key is NULL ln(%p)", __func__,
                            rt, ln);
                        /* NOTREACHED */
                }

                /* Set the flag in case we jump to "again" */
                ln->ln_flags |= ND6_LNF_TIMER_SKIP;

                if (ln->ln_expire > timenow.tv_sec) {
                        RT_UNLOCK(rt);
                        ln = next;
                        continue;
                }

                /* Make a copy (we're using it read-only anyway) */
                lck_rw_lock_shared(nd_if_rwlock);
                if (ifp->if_index >= nd_ifinfo_indexlim) {
                        lck_rw_done(nd_if_rwlock);
                        RT_UNLOCK(rt);
                        ln = next;
                        continue;
                }
                ndi = nd_ifinfo[ifp->if_index];
                lck_rw_done(nd_if_rwlock);

                RT_LOCK_ASSERT_HELD(rt);

                switch (ln->ln_state) {
                case ND6_LLINFO_INCOMPLETE:
                        if (ln->ln_asked < nd6_mmaxtries) {
                                ln->ln_asked++;
                                ln->ln_expire = timenow.tv_sec +
                                    ndi.retrans / 1000;
                                RT_ADDREF_LOCKED(rt);
                                RT_UNLOCK(rt);
                                lck_mtx_unlock(rnh_lock);
                                nd6_ns_output(ifp, NULL, &dst->sin6_addr,
                                        ln, 0, 0);
                                RT_REMREF(rt);
                        } else {
                                struct mbuf *m = ln->ln_hold;
                                ln->ln_hold = NULL;
                                if (m != NULL) {
                                        /*
                                         * Fake rcvif to make ICMP error
                                         * more helpful in diagnosing
                                         * for the receiver.
                                         * XXX: should we consider
                                         * older rcvif?
                                         */
                                        m->m_pkthdr.rcvif = ifp;
                                        RT_UNLOCK(rt);
                                        lck_mtx_unlock(rnh_lock);
                                        icmp6_error(m, ICMP6_DST_UNREACH,
                                                    ICMP6_DST_UNREACH_ADDR, 0);
                                } else {
                                        RT_UNLOCK(rt);
                                        lck_mtx_unlock(rnh_lock);
                                }
                                nd6_free(rt);
                        }
                        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
                        goto again;

                case ND6_LLINFO_REACHABLE:
                        if (ln->ln_expire) {
                                ln->ln_state = ND6_LLINFO_STALE;
                                ln->ln_expire = rt_expiry(rt, timenow.tv_sec,
                                    nd6_gctimer);
                        }
                        RT_UNLOCK(rt);
                        break;

                case ND6_LLINFO_STALE:
                case ND6_LLINFO_PURGE:
                        /* Garbage Collection(RFC 2461 5.3) */
                        if (ln->ln_expire) {
                                RT_UNLOCK(rt);
                                lck_mtx_unlock(rnh_lock);
                                nd6_free(rt);
                                lck_mtx_assert(rnh_lock,
                                    LCK_MTX_ASSERT_NOTOWNED);
                                goto again;
                        } else {
                                RT_UNLOCK(rt);
                        }
                        break;

                case ND6_LLINFO_DELAY:
                        if ((ndi.flags & ND6_IFF_PERFORMNUD) != 0) {
                                /* We need NUD */
                                ln->ln_asked = 1;
                                ln->ln_state = ND6_LLINFO_PROBE;
                                ln->ln_expire = timenow.tv_sec +
                                        ndi.retrans / 1000;
                                RT_ADDREF_LOCKED(rt);
                                RT_UNLOCK(rt);
                                lck_mtx_unlock(rnh_lock);
                                nd6_ns_output(ifp, &dst->sin6_addr,
                                    &dst->sin6_addr, ln, 0, 0);
                                lck_mtx_assert(rnh_lock,
                                    LCK_MTX_ASSERT_NOTOWNED);
                                RT_REMREF(rt);
                                goto again;
                        }
                        ln->ln_state = ND6_LLINFO_STALE; /* XXX */
                        ln->ln_expire = rt_expiry(rt, timenow.tv_sec,
                            nd6_gctimer);
                        RT_UNLOCK(rt);
                        break;

                case ND6_LLINFO_PROBE:
                        if (ln->ln_asked < nd6_umaxtries) {
                                ln->ln_asked++;
                                ln->ln_expire = timenow.tv_sec +
                                    ndi.retrans / 1000;
                                RT_ADDREF_LOCKED(rt);
                                RT_UNLOCK(rt);
                                lck_mtx_unlock(rnh_lock);
                                nd6_ns_output(ifp, &dst->sin6_addr,
                                    &dst->sin6_addr, ln, 0, 0);
                                RT_REMREF(rt);
                        } else {
                                RT_UNLOCK(rt);
                                lck_mtx_unlock(rnh_lock);
                                nd6_free(rt);
                        }
                        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
                        goto again;

                default:
                        RT_UNLOCK(rt);
                        break;
                }
                ln = next;
        }
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        /* Now clear the flag from all entries */
        ln = llinfo_nd6.ln_next;
        while (ln != NULL && ln != &llinfo_nd6) {
                struct rtentry *rt = ln->ln_rt;
                struct llinfo_nd6 *next = ln->ln_next;

                RT_LOCK_SPIN(rt);
                if (ln->ln_flags & ND6_LNF_TIMER_SKIP)
                        ln->ln_flags &= ~ND6_LNF_TIMER_SKIP;
                RT_UNLOCK(rt);
                ln = next;
        }
        lck_mtx_unlock(rnh_lock);

        /* expire default router list */
        lck_mtx_lock(nd6_mutex);
        dr = TAILQ_FIRST(&nd_defrouter);
        while (dr) {
                if (dr->expire && dr->expire < timenow.tv_sec) {
                        struct nd_defrouter *t;
                        t = TAILQ_NEXT(dr, dr_entry);
                        defrtrlist_del(dr, 1);
                        dr = t;
                } else {
                        dr = TAILQ_NEXT(dr, dr_entry);
                }
        }

        /*
         * expire interface addresses.
         * in the past the loop was inside prefix expiry processing.
         * However, from a stricter speci-confrmance standpoint, we should
         * rather separate address lifetimes and prefix lifetimes.
         */
  addrloop:
        for (ia6 = in6_ifaddrs; ia6; ia6 = nia6) {
                nia6 = ia6->ia_next;
                /* check address lifetime */
                lt6 = &ia6->ia6_lifetime;
                if (IFA6_IS_INVALID(ia6)) {
                        int regen = 0;

                        /*
                         * Extra reference for ourselves; it's no-op if
                         * we don't have to regenerate temporary address,
                         * otherwise it protects the address from going
                         * away since we drop nd6_mutex below.
                         */
                        ifaref(&ia6->ia_ifa);

                        /*
                         * 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) {
                                /* NOTE: We have to drop the lock here because 
                                 * regen_tmpaddr() eventually calls in6_update_ifa(),  
                                 * which must take the lock and would otherwise cause a 
                                 * hang. This is safe because the goto addrloop 
                                 * leads to a reevaluation of the in6_ifaddrs list
                                 */
                                lck_mtx_unlock(nd6_mutex);
                                if (regen_tmpaddr(ia6) == 0) 
                                        regen = 1;
                                lck_mtx_lock(nd6_mutex);
                        }

                        in6_purgeaddr(&ia6->ia_ifa, 1);

                        /* Release extra reference taken above */
                        ifafree(&ia6->ia_ifa);

                        if (regen)
                                goto addrloop; /* XXX: see below */
                }
                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) {

                                /* see NOTE above */
                                lck_mtx_unlock(nd6_mutex);
                                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??
                                         */
                                        lck_mtx_lock(nd6_mutex);
                                        goto addrloop;
                                }
                                lck_mtx_lock(nd6_mutex);
                        }
                } else {
                        /*
                         * A new RA might have made a deprecated address
                         * preferred.
                         */
                        ia6->ia6_flags &= ~IN6_IFF_DEPRECATED;
                }
        }

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

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

                        prelist_remove(pr, 1);
                        pr = t;
                } else
                        pr = pr->ndpr_next;
        }
        lck_mtx_unlock(nd6_mutex);
}

/*
 * ND6 timer routine to expire default route list and prefix list
 */
void
nd6_timer(__unused void *ignored_arg)
{
        nd6_drain(NULL);
        timeout(nd6_timer, (caddr_t)0, nd6_prune * hz);
}

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

        getmicrotime(&timenow);

        ifp = ia6->ia_ifa.ifa_ifp;
        ifnet_lock_exclusive(ifp);
        for (ifa = ifp->if_addrlist.tqh_first; ifa;
             ifa = ifa->ifa_list.tqe_next)
        {
                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;
        }
        ifnet_lock_done(ifp);

        if (public_ifa6 != NULL) {
                int e;

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

        return(-1);
}

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

        /* Nuke default router list entries toward ifp */
        lck_mtx_lock(nd6_mutex);
        if ((dr = TAILQ_FIRST(&nd_defrouter)) != NULL) {
                /*
                 * The first entry of the list may be stored in
                 * the routing table, so we'll delete it later.
                 */
                for (dr = TAILQ_NEXT(dr, dr_entry); dr; dr = ndr) {
                        ndr = TAILQ_NEXT(dr, dr_entry);
                        if (dr->ifp == ifp)
                                defrtrlist_del(dr, 1);
                }
                dr = TAILQ_FIRST(&nd_defrouter);
                if (dr->ifp == ifp)
                        defrtrlist_del(dr, 1);
        }

        /* Nuke prefix list entries toward ifp */
        for (pr = nd_prefix.lh_first; pr; pr = npr) {
                npr = pr->ndpr_next;
                if (pr->ndpr_ifp == ifp) {
                        /*
                         * Previously, pr->ndpr_addr is removed as well,
                         * but I strongly believe we don't have to do it.
                         * nd6_purge() is only called from in6_ifdetach(),
                         * which removes all the associated interface addresses
                         * by itself.
                         * (jinmei@kame.net 20010129)
                         */
                        prelist_remove(pr, 1);
                }
        }

        /* cancel default outgoing interface setting */
        if (nd6_defifindex == ifp->if_index) {
                /* Release nd6_mutex as it will be acquired 
                 * during nd6_setdefaultiface again
                 */ 
                lck_mtx_unlock(nd6_mutex);
                nd6_setdefaultiface(0);
                lck_mtx_lock(nd6_mutex);
        }

        if (!ip6_forwarding && (ip6_accept_rtadv || (ifp->if_eflags & IFEF_ACCEPT_RTADVD))) { 
                /* refresh default router list */
                bzero(&drany, sizeof(drany));
                defrouter_delreq(&drany, 0);
                defrouter_select();
        }
        lck_mtx_unlock(nd6_mutex);

        /*
         * 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().
         */
again:
        lck_mtx_lock(rnh_lock);
        ln = llinfo_nd6.ln_next;
        while (ln != NULL && ln != &llinfo_nd6) {
                struct rtentry *rt;
                struct llinfo_nd6 *nln;

                nln = ln->ln_next;
                rt = ln->ln_rt;
                RT_LOCK(rt);
                if (rt->rt_gateway != NULL &&
                    rt->rt_gateway->sa_family == AF_LINK &&
                    SDL(rt->rt_gateway)->sdl_index == ifp->if_index) {
                        RT_UNLOCK(rt);
                        lck_mtx_unlock(rnh_lock);
                        /*
                         * See comments on nd6_timer() for reasons why
                         * this loop is repeated; we bite the costs of
                         * going thru the same llinfo_nd6 more than once
                         * here, since this purge happens during detach,
                         * and that unlike the timer case, it's possible
                         * there's more than one purges happening at the
                         * same time (thus a flag wouldn't buy anything).
                         */
                        nd6_free(rt);
                        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
                        goto again;
                } else {
                        RT_UNLOCK(rt);
                }
                ln = nln;
        }
        lck_mtx_unlock(rnh_lock);
}

/*
 * Upon success, the returned route will be locked and the caller is
 * responsible for releasing the reference and doing RT_UNLOCK(rt).
 * This routine does not require rnh_lock to be held by the caller,
 * although it needs to be indicated of such a case in order to call
 * the correct variant of the relevant routing routines.
 */
struct rtentry *
nd6_lookup(
        struct in6_addr *addr6,
        int create,
        struct ifnet *ifp,
        int rt_locked)
{
        struct rtentry *rt;
        struct sockaddr_in6 sin6;

        bzero(&sin6, sizeof(sin6));
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_addr = *addr6;
#if SCOPEDROUTING
        sin6.sin6_scope_id = in6_addr2scopeid(ifp, addr6);
#endif
        if (rt_locked)
                lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        rt = rt_locked ? rtalloc1_locked((struct sockaddr *)&sin6, create, 0) :
            rtalloc1((struct sockaddr *)&sin6, create, 0);

        if (rt != NULL) {
                RT_LOCK(rt);
                if ((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) {
                                RT_UNLOCK(rt);
                                if (rt_locked)
                                        rtfree_locked(rt);
                                else
                                        rtfree(rt);
                                rt = NULL;
                        }
                }
        }
        if (rt == NULL) {
                if (create && ifp) {
                        struct ifaddr *ifa;
                        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.
                         */
                        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 (!rt_locked)
                                lck_mtx_lock(rnh_lock);
                        if ((e = rtrequest_locked(RTM_ADD,
                            (struct sockaddr *)&sin6, ifa->ifa_addr,
                            (struct sockaddr *)&all1_sa,
                            (ifa->ifa_flags | RTF_HOST | RTF_LLINFO) &
                            ~RTF_CLONING, &rt)) != 0) {
                                if (e != EEXIST)
                                        log(LOG_ERR, "%s: failed to add route "
                                            "for a neighbor(%s), errno=%d\n",
                                            __func__, ip6_sprintf(addr6), e);
                        }
                        if (!rt_locked)
                                lck_mtx_unlock(rnh_lock);
                        ifafree(ifa);
                        if (rt == NULL)
                                return(NULL);

                        RT_LOCK(rt);
                        if (rt->rt_llinfo) {
                                struct llinfo_nd6 *ln = rt->rt_llinfo;
                                ln->ln_state = ND6_LLINFO_NOSTATE;
                        }
                } else {
                        return(NULL);
                }
        }
        RT_LOCK_ASSERT_HELD(rt);
        /*
         * 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.
         */
        if (ifp == NULL || (ifp->if_type == IFT_PPP) ||
            (ifp->if_eflags & IFEF_NOAUTOIPV6LL) ||
            (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)) {
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                if (create) {
                        log(LOG_DEBUG, "%s: failed to lookup %s "
                            "(if = %s)\n", __func__, ip6_sprintf(addr6),
                            ifp ? if_name(ifp) : "unspec");
                        /* xxx more logs... kazu */
                }
                return(NULL);
        }
        /*
         * Caller needs to release reference and call RT_UNLOCK(rt).
         */
        return(rt);
}

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

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

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

        /*
         * If the address matches one of our addresses,
         * it should be a neighbor.
         */
        ifnet_lock_shared(ifp);
        for (ifa = ifp->if_addrlist.tqh_first;
             ifa;
             ifa = ifa->ifa_list.tqe_next)
        {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                for (i = 0; i < 4; i++) {
                        if ((IFADDR6(ifa).s6_addr32[i] ^
                             addr->sin6_addr.s6_addr32[i]) &
                                IFMASK6(ifa).s6_addr32[i])
                                continue;
                }
                ifnet_lock_done(ifp);
                return(1);
        }
        ifnet_lock_done(ifp);

        /*
         * Even if the address matches none of our addresses, it might be
         * in the neighbor cache.  Callee returns a locked route upon
         * success.
         */
        if ((rt = nd6_lookup(&addr->sin6_addr, 0, ifp, rt_locked)) != NULL) {
                RT_LOCK_ASSERT_HELD(rt);
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                return(1);
        }

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

/*
 * Free an nd6 llinfo entry.
 */
void
nd6_free(
        struct rtentry *rt)
{
        struct llinfo_nd6 *ln;
        struct in6_addr in6;
        struct nd_defrouter *dr;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        RT_LOCK_ASSERT_NOTHELD(rt);
        lck_mtx_lock(nd6_mutex);

        RT_LOCK(rt);
        RT_ADDREF_LOCKED(rt);   /* Extra ref */
        ln = rt->rt_llinfo;
        in6 = ((struct sockaddr_in6 *)rt_key(rt))->sin6_addr;

        /*
         * Prevent another thread from modifying rt_key, rt_gateway
         * via rt_setgate() after the rt_lock is dropped by marking
         * the route as defunct.
         */
        rt->rt_flags |= RTF_CONDEMNED;

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

        if (!ip6_forwarding && (ip6_accept_rtadv ||
            (rt->rt_ifp->if_eflags & IFEF_ACCEPT_RTADVD))) {
                dr = defrouter_lookup(&((struct sockaddr_in6 *)rt_key(rt))->
                    sin6_addr, rt->rt_ifp);

                if ((ln && 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().
                         */
                        RT_UNLOCK(rt);
                        rt6_flush(&in6, rt->rt_ifp);
                } else {
                        RT_UNLOCK(rt);
                }

                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.
                         */
                        RT_LOCK_SPIN(rt);
                        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.
                         */
                        RT_UNLOCK(rt);
                        pfxlist_onlink_check(1);

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

                                defrouter_select();
                        }
                }
                RT_LOCK_ASSERT_NOTHELD(rt);
        } else {
                RT_UNLOCK(rt);
        }

        lck_mtx_unlock(nd6_mutex);
        /*
         * 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.
         */
        (void) rtrequest(RTM_DELETE, rt_key(rt), (struct sockaddr *)0,
                  rt_mask(rt), 0, (struct rtentry **)0);

        /* Extra ref held above; now free it */
        rtfree(rt);
}

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

        getmicrotime(&timenow);

        /*
         * If the caller specified "rt", use that.  Otherwise, resolve the
         * routing table by supplied "dst6".
         */
        if (!rt) {
                if (!dst6)
                        return;
                /* Callee returns a locked route upon success */
                if ((rt = nd6_lookup(dst6, 0, NULL, 0)) == NULL)
                        return;
                RT_LOCK_ASSERT_HELD(rt);
        } else {
                RT_LOCK(rt);
                RT_ADDREF_LOCKED(rt);
        }

        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. */
                goto done;
        }

        ln = rt->rt_llinfo;
        if (ln->ln_state < ND6_LLINFO_REACHABLE)
                goto done;

        /*
         * 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)
                        goto done;
        }

        ln->ln_state = ND6_LLINFO_REACHABLE;
        if (ln->ln_expire) {
                lck_rw_lock_shared(nd_if_rwlock);
                ln->ln_expire = rt_expiry(rt, timenow.tv_sec,
                        nd_ifinfo[rt->rt_ifp->if_index].reachable);
                lck_rw_done(nd_if_rwlock);
        }
done:
        RT_REMREF_LOCKED(rt);
        RT_UNLOCK(rt);
}

void
nd6_rtrequest(
        int     req,
        struct rtentry *rt,
        __unused struct sockaddr *sa)
{
        struct sockaddr *gate = rt->rt_gateway;
        struct llinfo_nd6 *ln = rt->rt_llinfo;
        static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK, 0, 0, 0, 0, 0, 
                                                                                        {0,0,0,0,0,0,0,0,0,0,0,0,} };
        struct ifnet *ifp = rt->rt_ifp;
        struct ifaddr *ifa;
        struct timeval timenow;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        RT_LOCK_ASSERT_HELD(rt);

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

        if (nd6_need_cache(ifp) == 0 && (rt->rt_flags & RTF_HOST) == 0) {
                /*
                 * 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) {
                int no_nd_cache;

                if (!nd6_need_cache(ifp)) {     /* stf case */
                        no_nd_cache = 1;
                } else {
                        /*
                         * nd6_is_addr_neighbor() may call nd6_lookup(),
                         * therefore we drop rt_lock to avoid deadlock
                         * during the lookup.  Using rt_key(rt) is still
                         * safe because it won't change while rnh_lock
                         * is held.
                         */
                        RT_ADDREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                        no_nd_cache = !nd6_is_addr_neighbor(
                            (struct sockaddr_in6 *)rt_key(rt), ifp, 1);
                        RT_LOCK(rt);
                        RT_REMREF_LOCKED(rt);
                }

                /*
                 * 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.
                 */
                if (no_nd_cache) {
                        rt->rt_flags &= ~RTF_LLINFO;
                        return;
                }
        }

        getmicrotime(&timenow);
        switch (req) {
        case RTM_ADD:
                /*
                 * 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 | RTF_LLINFO)) {
                        /*
                         * Case 1: This route should come from
                         * a route to interface.  RTF_LLINFO flag is set
                         * for a host route whose destination should be
                         * treated as on-link.
                         */
                        if (rt_setgate(rt, rt_key(rt),
                            (struct sockaddr *)&null_sdl) == 0) {
                                gate = rt->rt_gateway;
                                SDL(gate)->sdl_type = ifp->if_type;
                                SDL(gate)->sdl_index = ifp->if_index;
                                /*
                                 * In case we're called before 1.0 sec.
                                 * has elapsed.
                                 */
                                if (ln != NULL)
                                        ln->ln_expire = MAX(timenow.tv_sec, 1);
                        }
                        if ((rt->rt_flags & RTF_CLONING))
                                break;
                }
                /*
                 * In IPv4 code, we try to annonuce new RTF_ANNOUNCE entry here.
                 * We don't do that here since llinfo is not ready yet.
                 *
                 * There are also couple of other things to be discussed:
                 * - unsolicited NA code needs improvement beforehand
                 * - RFC2461 says we MAY send multicast unsolicited NA
                 *   (7.2.6 paragraph 4), however, it also says that we
                 *   SHOULD provide a mechanism to prevent multicast NA storm.
                 *   we don't have anything like it right now.
                 *   note that the mechanism needs a mutual agreement
                 *   between proxies, which means that we need to implement
                 *   a new protocol, or a new kludge.
                 * - from RFC2461 6.2.4, host MUST NOT send an unsolicited NA.
                 *   we need to check ip6forwarding before sending it.
                 *   (or should we allow proxy ND configuration only for
                 *   routers?  there's no mention about proxy ND from hosts)
                 */
#if 0
                /* XXX it does not work */
                if (rt->rt_flags & RTF_ANNOUNCE)
                        nd6_na_output(ifp,
                              &SIN6(rt_key(rt))->sin6_addr,
                              &SIN6(rt_key(rt))->sin6_addr,
                              ip6_forwarding ? ND_NA_FLAG_ROUTER : 0,
                              1, NULL);
#endif
                /* FALLTHROUGH */
        case RTM_RESOLVE:
                if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) == 0) {
                        /*
                         * Address resolution isn't necessary for a point to
                         * point link, so we can skip this test for a p2p link.
                         */
                        if (gate->sa_family != AF_LINK ||
                            gate->sa_len < sizeof(null_sdl)) {
                                log(LOG_DEBUG,
                                    "nd6_rtrequest: bad gateway value: %s\n",
                                    if_name(ifp));
                                break;
                        }
                        SDL(gate)->sdl_type = ifp->if_type;
                        SDL(gate)->sdl_index = ifp->if_index;
                }
                if (ln != NULL)
                        break;  /* This happens on a route change */
                /*
                 * Case 2: This route may come from cloning, or a manual route
                 * add with a LL address.
                 */
                rt->rt_llinfo = ln = nd6_llinfo_alloc();
                if (ln == NULL) {
                        log(LOG_DEBUG, "nd6_rtrequest: malloc failed\n");
                        break;
                }
                rt->rt_llinfo_free = nd6_llinfo_free;

                nd6_inuse++;
                nd6_allocated++;
                Bzero(ln, sizeof(*ln));
                ln->ln_rt = rt;
                /* this is required for "ndp" command. - shin */
                if (req == RTM_ADD) {
                        /*
                         * gate should have some valid AF_LINK entry,
                         * and ln->ln_expire should have some lifetime
                         * which is specified by ndp command.
                         */
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
                } else {
                        /*
                         * When req == RTM_RESOLVE, rt is created and
                         * initialized in rtrequest(), so rt_expire is 0.
                         */
                        ln->ln_state = ND6_LLINFO_NOSTATE;
                        /* In case we're called before 1.0 sec. has elapsed */
                        ln->ln_expire = MAX(timenow.tv_sec, 1);
                }
                rt->rt_flags |= RTF_LLINFO;
                LN_INSERTHEAD(ln);

                /*
                 * If we have too many cache entries, initiate immediate
                 * purging for some "less recently used" entries.  Note that
                 * we cannot directly call nd6_free() here because it would
                 * cause re-entering rtable related routines triggering an LOR
                 * problem.
                 */
                if (ip6_neighborgcthresh >= 0 &&
                    nd6_inuse >= ip6_neighborgcthresh) {
                        int i;

                        for (i = 0; i < 10 && llinfo_nd6.ln_prev != ln; i++) {
                                struct llinfo_nd6 *ln_end = llinfo_nd6.ln_prev;
                                struct rtentry *rt_end = ln_end->ln_rt;

                                /* Move this entry to the head */
                                RT_LOCK(rt_end);
                                LN_DEQUEUE(ln_end);
                                LN_INSERTHEAD(ln_end);

                                if (ln_end->ln_expire == 0) {
                                        RT_UNLOCK(rt_end);
                                        continue;
                                }
                                if (ln_end->ln_state > ND6_LLINFO_INCOMPLETE)
                                        ln_end->ln_state = ND6_LLINFO_STALE;
                                else
                                        ln_end->ln_state = ND6_LLINFO_PURGE;
                                ln_end->ln_expire = timenow.tv_sec;
                                RT_UNLOCK(rt_end);
                        }
                }

                /*
                 * check if rt_key(rt) is one of my address assigned
                 * to the interface.
                 */
                ifa = (struct ifaddr *)in6ifa_ifpwithaddr(rt->rt_ifp,
                                          &SIN6(rt_key(rt))->sin6_addr);
                if (ifa) {
                        caddr_t macp = nd6_ifptomac(ifp);
                        ln->ln_expire = 0;
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
                        if (macp) {
                                Bcopy(macp, LLADDR(SDL(gate)), ifp->if_addrlen);
                                SDL(gate)->sdl_alen = ifp->if_addrlen;
                        }
                        if (nd6_useloopback) {
#if IFNET_ROUTE_REFCNT
                                /* Adjust route ref count for the interfaces */
                                if (rt->rt_if_ref_fn != NULL &&
                                    rt->rt_ifp != lo_ifp) {
                                        rt->rt_if_ref_fn(lo_ifp, 1);
                                        rt->rt_if_ref_fn(rt->rt_ifp, -1);
                                }
#endif /* IFNET_ROUTE_REFCNT */
                                rt->rt_ifp = lo_ifp;    /* 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) {
                                        rtsetifa(rt, ifa);
                                }
                        }
                        ifafree(ifa);
                } else if (rt->rt_flags & RTF_ANNOUNCE) {
                        ln->ln_expire = 0;
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;

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

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

                                if (!in6_addmulti(&llsol, ifp, &error, 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)
                        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 = SIN6(rt_key(rt))->sin6_addr;
                        llsol.s6_addr16[0] = htons(0xff02);
                        llsol.s6_addr16[1] = htons(ifp->if_index);
                        llsol.s6_addr32[1] = 0;
                        llsol.s6_addr32[2] = htonl(1);
                        llsol.s6_addr8[12] = 0xff;

                        ifnet_lock_shared(ifp);
                        IN6_LOOKUP_MULTI(llsol, ifp, in6m);
                        ifnet_lock_done(ifp);
                        if (in6m)
                                in6_delmulti(in6m, 0);
                }
                nd6_inuse--;
                /*
                 * Unchain it but defer the actual freeing until the route
                 * itself is to be freed.  rt->rt_llinfo still points to
                 * llinfo_nd6, and likewise, ln->ln_rt stil points to this
                 * route entry, except that RTF_LLINFO is now cleared.
                 */
                if (ln->ln_flags & ND6_LNF_IN_USE)
                        LN_DEQUEUE(ln);
                rt->rt_flags &= ~RTF_LLINFO;
                if (ln->ln_hold != NULL)
                        m_freem(ln->ln_hold);
                ln->ln_hold = NULL;
        }
}

static void
nd6_siocgdrlst(void *data, int data_is_64)
{
        struct in6_drlist_64 *drl_64 = (struct in6_drlist_64 *)data;
        struct in6_drlist_32 *drl_32 = (struct in6_drlist_32 *)data;
        struct nd_defrouter *dr;
        int i = 0;

        lck_mtx_assert(nd6_mutex, LCK_MTX_ASSERT_OWNED);

        bzero(data, data_is_64 ? sizeof (*drl_64) : sizeof (*drl_32));
        dr = TAILQ_FIRST(&nd_defrouter);
        if (data_is_64) {
                /* For 64-bit process */
                while (dr && i < DRLSTSIZ) {
                        drl_64->defrouter[i].rtaddr = dr->rtaddr;
                        if (IN6_IS_ADDR_LINKLOCAL(&drl_64->defrouter[i].rtaddr)) {
                                /* XXX: need to this hack for KAME stack */
                                drl_64->defrouter[i].rtaddr.s6_addr16[1] = 0;
                        } else {
                                log(LOG_ERR,
                                    "default router list contains a "
                                    "non-linklocal address(%s)\n",
                                    ip6_sprintf(&drl_64->defrouter[i].rtaddr));
                        }
                        drl_64->defrouter[i].flags = dr->flags;
                        drl_64->defrouter[i].rtlifetime = dr->rtlifetime;
                        drl_64->defrouter[i].expire = dr->expire;
                        drl_64->defrouter[i].if_index = dr->ifp->if_index;
                        i++;
                        dr = TAILQ_NEXT(dr, dr_entry);
                }
                return;
        }
        /* For 32-bit process */
        while (dr && i < DRLSTSIZ) {
                drl_32->defrouter[i].rtaddr = dr->rtaddr;
                if (IN6_IS_ADDR_LINKLOCAL(&drl_32->defrouter[i].rtaddr)) {
                        /* XXX: need to this hack for KAME stack */
                        drl_32->defrouter[i].rtaddr.s6_addr16[1] = 0;
                } else {
                        log(LOG_ERR,
                            "default router list contains a "
                            "non-linklocal address(%s)\n",
                            ip6_sprintf(&drl_32->defrouter[i].rtaddr));
                }
                drl_32->defrouter[i].flags = dr->flags;
                drl_32->defrouter[i].rtlifetime = dr->rtlifetime;
                drl_32->defrouter[i].expire = dr->expire;
                drl_32->defrouter[i].if_index = dr->ifp->if_index;
                i++;
                dr = TAILQ_NEXT(dr, dr_entry);
        }
}

static void
nd6_siocgprlst(void *data, int data_is_64)
{
        struct in6_prlist_64 *prl_64 = (struct in6_prlist_64 *)data;
        struct in6_prlist_32 *prl_32 = (struct in6_prlist_32 *)data;
        struct nd_prefix *pr;
        struct rr_prefix *rpp;
        int i = 0;

        lck_mtx_assert(nd6_mutex, LCK_MTX_ASSERT_OWNED);
        /*
         * XXX meaning of fields, especialy "raflags", is very
         * differnet between RA prefix list and RR/static prefix list.
         * how about separating ioctls into two?
         */
        bzero(data, data_is_64 ? sizeof (*prl_64) : sizeof (*prl_32));
        pr = nd_prefix.lh_first;
        if (data_is_64) {
                /* For 64-bit process */
                while (pr && i < PRLSTSIZ) {
                        struct nd_pfxrouter *pfr;
                        int j;

                        (void) in6_embedscope(&prl_64->prefix[i].prefix,
                            &pr->ndpr_prefix, NULL, NULL);
                        prl_64->prefix[i].raflags = pr->ndpr_raf;
                        prl_64->prefix[i].prefixlen = pr->ndpr_plen;
                        prl_64->prefix[i].vltime = pr->ndpr_vltime;
                        prl_64->prefix[i].pltime = pr->ndpr_pltime;
                        prl_64->prefix[i].if_index = pr->ndpr_ifp->if_index;
                        prl_64->prefix[i].expire = pr->ndpr_expire;

                        pfr = pr->ndpr_advrtrs.lh_first;
                        j = 0;
                        while (pfr) {
                                if (j < DRLSTSIZ) {
#define RTRADDR prl_64->prefix[i].advrtr[j]
                                        RTRADDR = pfr->router->rtaddr;
                                        if (IN6_IS_ADDR_LINKLOCAL(&RTRADDR)) {
                                                /* XXX: hack for KAME */
                                                RTRADDR.s6_addr16[1] = 0;
                                        } else {
                                                log(LOG_ERR,
                                                    "a router(%s) advertises "
                                                    "a prefix with "
                                                    "non-link local address\n",
                                                    ip6_sprintf(&RTRADDR));
                                        }
#undef RTRADDR
                                }
                                j++;
                                pfr = pfr->pfr_next;
                        }
                        prl_64->prefix[i].advrtrs = j;
                        prl_64->prefix[i].origin = PR_ORIG_RA;

                        i++;
                        pr = pr->ndpr_next;
                }

                for (rpp = LIST_FIRST(&rr_prefix); rpp;
                     rpp = LIST_NEXT(rpp, rp_entry)) {
                        if (i >= PRLSTSIZ)
                                break;
                        (void) in6_embedscope(&prl_64->prefix[i].prefix,
                            &pr->ndpr_prefix, NULL, NULL);
                        prl_64->prefix[i].raflags = rpp->rp_raf;
                        prl_64->prefix[i].prefixlen = rpp->rp_plen;
                        prl_64->prefix[i].vltime = rpp->rp_vltime;
                        prl_64->prefix[i].pltime = rpp->rp_pltime;
                        prl_64->prefix[i].if_index = rpp->rp_ifp->if_index;
                        prl_64->prefix[i].expire = rpp->rp_expire;
                        prl_64->prefix[i].advrtrs = 0;
                        prl_64->prefix[i].origin = rpp->rp_origin;
                        i++;
                }
                return;
        }
        /* For 32-bit process */
        while (pr && i < PRLSTSIZ) {
                struct nd_pfxrouter *pfr;
                int j;

                (void) in6_embedscope(&prl_32->prefix[i].prefix,
                    &pr->ndpr_prefix, NULL, NULL);
                prl_32->prefix[i].raflags = pr->ndpr_raf;
                prl_32->prefix[i].prefixlen = pr->ndpr_plen;
                prl_32->prefix[i].vltime = pr->ndpr_vltime;
                prl_32->prefix[i].pltime = pr->ndpr_pltime;
                prl_32->prefix[i].if_index = pr->ndpr_ifp->if_index;
                prl_32->prefix[i].expire = pr->ndpr_expire;

                pfr = pr->ndpr_advrtrs.lh_first;
                j = 0;
                while (pfr) {
                        if (j < DRLSTSIZ) {
#define RTRADDR prl_32->prefix[i].advrtr[j]
                                RTRADDR = pfr->router->rtaddr;
                                if (IN6_IS_ADDR_LINKLOCAL(&RTRADDR)) {
                                        /* XXX: hack for KAME */
                                        RTRADDR.s6_addr16[1] = 0;
                                } else {
                                        log(LOG_ERR,
                                            "a router(%s) advertises "
                                            "a prefix with "
                                            "non-link local address\n",
                                            ip6_sprintf(&RTRADDR));
                                }
#undef RTRADDR
                        }
                        j++;
                        pfr = pfr->pfr_next;
                }
                prl_32->prefix[i].advrtrs = j;
                prl_32->prefix[i].origin = PR_ORIG_RA;

                i++;
                pr = pr->ndpr_next;
        }

        for (rpp = LIST_FIRST(&rr_prefix); rpp;
             rpp = LIST_NEXT(rpp, rp_entry)) {
                if (i >= PRLSTSIZ)
                        break;
                (void) in6_embedscope(&prl_32->prefix[i].prefix,
                    &pr->ndpr_prefix, NULL, NULL);
                prl_32->prefix[i].raflags = rpp->rp_raf;
                prl_32->prefix[i].prefixlen = rpp->rp_plen;
                prl_32->prefix[i].vltime = rpp->rp_vltime;
                prl_32->prefix[i].pltime = rpp->rp_pltime;
                prl_32->prefix[i].if_index = rpp->rp_ifp->if_index;
                prl_32->prefix[i].expire = rpp->rp_expire;
                prl_32->prefix[i].advrtrs = 0;
                prl_32->prefix[i].origin = rpp->rp_origin;
                i++;
        }
}

int
nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
{
        struct in6_ndireq *ndi = (struct in6_ndireq *)data;
        struct in6_ondireq *ondi = (struct in6_ondireq *)data;
        struct nd_defrouter *dr, any;
        struct nd_prefix *pr;
        struct rtentry *rt;
        int i = ifp->if_index, error = 0;

        switch (cmd) {
        case SIOCGDRLST_IN6_32:
        case SIOCGDRLST_IN6_64:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                lck_mtx_lock(nd6_mutex);
                nd6_siocgdrlst(data, cmd == SIOCGDRLST_IN6_64);
                lck_mtx_unlock(nd6_mutex);
                break;

        case SIOCGPRLST_IN6_32:
        case SIOCGPRLST_IN6_64:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                lck_mtx_lock(nd6_mutex);
                nd6_siocgprlst(data, cmd == SIOCGPRLST_IN6_64);
                lck_mtx_unlock(nd6_mutex);
                break;

        case OSIOCGIFINFO_IN6:
        case SIOCGIFINFO_IN6:
                /*
                 * SIOCGIFINFO_IN6 ioctl is encoded with in6_ondireq
                 * instead of in6_ndireq, so we treat it as such.
                 */
                lck_rw_lock_shared(nd_if_rwlock);
                if (!nd_ifinfo || i >= nd_ifinfo_indexlim) {
                        lck_rw_done(nd_if_rwlock);
                        error = EINVAL;
                        break;
                }
                ondi->ndi.linkmtu = IN6_LINKMTU(ifp);
                ondi->ndi.maxmtu = nd_ifinfo[i].maxmtu;
                ondi->ndi.basereachable = nd_ifinfo[i].basereachable;
                ondi->ndi.reachable = nd_ifinfo[i].reachable;
                ondi->ndi.retrans = nd_ifinfo[i].retrans;
                ondi->ndi.flags = nd_ifinfo[i].flags;
                ondi->ndi.recalctm = nd_ifinfo[i].recalctm;
                ondi->ndi.chlim = nd_ifinfo[i].chlim;
                ondi->ndi.receivedra = nd_ifinfo[i].receivedra;
                lck_rw_done(nd_if_rwlock);
                break;

        case SIOCSIFINFO_FLAGS:
                /* XXX: almost all other fields of ndi->ndi is unused */
                lck_rw_lock_shared(nd_if_rwlock);
                if (!nd_ifinfo || i >= nd_ifinfo_indexlim) {
                        lck_rw_done(nd_if_rwlock);
                        error = EINVAL;
                        break;
                }
                nd_ifinfo[i].flags = ndi->ndi.flags;
                lck_rw_done(nd_if_rwlock);
                break;

        case SIOCSNDFLUSH_IN6:  /* XXX: the ioctl name is confusing... */
                /* flush default router list */
                /*
                 * xxx sumikawa: should not delete route if default
                 * route equals to the top of default router list
                 */
                bzero(&any, sizeof(any));
                lck_mtx_lock(nd6_mutex);
                defrouter_delreq(&any, 1);
                defrouter_select();
                lck_mtx_unlock(nd6_mutex);
                /* xxx sumikawa: flush prefix list */
                break;

        case SIOCSPFXFLUSH_IN6: {
                /* flush all the prefix advertised by routers */
                struct nd_prefix *next;
                lck_mtx_lock(nd6_mutex);

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

                        next = pr->ndpr_next;

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

                        /* do we really have to remove addresses as well? */
                        for (ia = in6_ifaddrs; 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 == pr)
                                        in6_purgeaddr(&ia->ia_ifa, 1);
                        }
                        prelist_remove(pr, 1);
                }
                lck_mtx_unlock(nd6_mutex);
                break;
        }

        case SIOCSRTRFLUSH_IN6: {
                /* flush all the default routers */
                struct nd_defrouter *next;

                lck_mtx_lock(nd6_mutex);
                if ((dr = TAILQ_FIRST(&nd_defrouter)) != NULL) {
                        /*
                         * The first entry of the list may be stored in
                         * the routing table, so we'll delete it later.
                         */
                        for (dr = TAILQ_NEXT(dr, dr_entry); dr; dr = next) {
                                next = TAILQ_NEXT(dr, dr_entry);
                                defrtrlist_del(dr, 1);
                        }
                        defrtrlist_del(TAILQ_FIRST(&nd_defrouter), 1);
                }
                lck_mtx_unlock(nd6_mutex);
                break;
        }

        case SIOCGNBRINFO_IN6_32: {
                struct llinfo_nd6 *ln;
                struct in6_nbrinfo_32 *nbi_32 = (struct in6_nbrinfo_32 *)data;
                /* make local for safety */
                struct in6_addr nb_addr = nbi_32->addr;

                /*
                 * XXX: KAME specific hack for scoped addresses
                 *      XXXX: for other scopes than link-local?
                 */
                if (IN6_IS_ADDR_LINKLOCAL(&nbi_32->addr) ||
                    IN6_IS_ADDR_MC_LINKLOCAL(&nbi_32->addr)) {
                        u_int16_t *idp = (u_int16_t *)&nb_addr.s6_addr[2];

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

                /* Callee returns a locked route upon success */
                if ((rt = nd6_lookup(&nb_addr, 0, ifp, 0)) == NULL) {
                        error = EINVAL;
                        break;
                }
                RT_LOCK_ASSERT_HELD(rt);
                ln = rt->rt_llinfo;
                nbi_32->state = ln->ln_state;
                nbi_32->asked = ln->ln_asked;
                nbi_32->isrouter = ln->ln_router;
                nbi_32->expire = ln->ln_expire;
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                break;
        }

        case SIOCGNBRINFO_IN6_64: {
                struct llinfo_nd6 *ln;
                struct in6_nbrinfo_64 *nbi_64 = (struct in6_nbrinfo_64 *)data;
                /* make local for safety */
                struct in6_addr nb_addr = nbi_64->addr;

                /*
                 * XXX: KAME specific hack for scoped addresses
                 *      XXXX: for other scopes than link-local?
                 */
                if (IN6_IS_ADDR_LINKLOCAL(&nbi_64->addr) ||
                    IN6_IS_ADDR_MC_LINKLOCAL(&nbi_64->addr)) {
                        u_int16_t *idp = (u_int16_t *)&nb_addr.s6_addr[2];

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

                /* Callee returns a locked route upon success */
                if ((rt = nd6_lookup(&nb_addr, 0, ifp, 0)) == NULL) {
                        error = EINVAL;
                        break;
                }
                RT_LOCK_ASSERT_HELD(rt);
                ln = rt->rt_llinfo;
                nbi_64->state = ln->ln_state;
                nbi_64->asked = ln->ln_asked;
                nbi_64->isrouter = ln->ln_router;
                nbi_64->expire = ln->ln_expire;
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                break;
        }

        case SIOCGDEFIFACE_IN6_32: /* XXX: should be implemented as a sysctl? */
        case SIOCGDEFIFACE_IN6_64: {
                struct in6_ndifreq_64 *ndif_64 = (struct in6_ndifreq_64 *)data;
                struct in6_ndifreq_32 *ndif_32 = (struct in6_ndifreq_32 *)data;

                if (cmd == SIOCGDEFIFACE_IN6_64)
                        ndif_64->ifindex = nd6_defifindex;
                else
                        ndif_32->ifindex = nd6_defifindex;
                break;
        }

        case SIOCSDEFIFACE_IN6_32: /* XXX: should be implemented as a sysctl? */
        case SIOCSDEFIFACE_IN6_64: {
                struct in6_ndifreq_64 *ndif_64 = (struct in6_ndifreq_64 *)data;
                struct in6_ndifreq_32 *ndif_32 = (struct in6_ndifreq_32 *)data;

                return (nd6_setdefaultiface(cmd == SIOCSDEFIFACE_IN6_64 ?
                    ndif_64->ifindex : ndif_32->ifindex));
                /* NOTREACHED */
        }
        }
        return (error);
}

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

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

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

        /*
         * 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).
         */
        getmicrotime(&timenow);

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

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

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

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

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

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

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

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

                if (ln->ln_state == ND6_LLINFO_STALE) {
                        struct mbuf *m = ln->ln_hold;
                        /*
                         * XXX: since nd6_output() below will cause
                         * state tansition to DELAY and reset the timer,
                         * we must set the timer now, although it is actually
                         * meaningless.
                         */
                        ln->ln_expire = rt_expiry(rt, timenow.tv_sec,
                            nd6_gctimer);
                        ln->ln_hold = NULL;

                        if (m != NULL) {
                                /*
                                 * we assume ifp is not a p2p here, so just
                                 * set the 2nd argument as the 1st one.
                                 */
                                RT_UNLOCK(rt);
                                nd6_output(ifp, ifp, m,
                                    (struct sockaddr_in6 *)rt_key(rt), rt, 0);
                                RT_LOCK(rt);
                        }
                } else if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
                        /* probe right away */
                        ln->ln_expire = timenow.tv_sec;
                }
        }

        /*
         * 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 &&
            (ip6_accept_rtadv || (ifp->if_eflags & IFEF_ACCEPT_RTADVD))) {
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                lck_mtx_lock(nd6_mutex);
                defrouter_select();
                lck_mtx_unlock(nd6_mutex);
        } else {
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
        }
}

static void
nd6_slowtimo(
    __unused void *ignored_arg)
{
        int i;
        struct nd_ifinfo *nd6if;

        lck_rw_lock_shared(nd_if_rwlock);
        for (i = 1; i < if_index + 1; i++) {
                if (!nd_ifinfo || i >= nd_ifinfo_indexlim)
                        break;
                nd6if = &nd_ifinfo[i];
                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);
                }
        }
        lck_rw_done(nd_if_rwlock);
        timeout(nd6_slowtimo, (caddr_t)0, ND6_SLOWTIMER_INTERVAL * hz);
}

#define senderr(e) { error = (e); goto bad;}
int
nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m0,
    struct sockaddr_in6 *dst, struct rtentry *hint0, int locked)
{
        struct mbuf *m = m0;
        struct rtentry *rt = hint0, *hint = hint0;
        struct llinfo_nd6 *ln = NULL;
        int error = 0;
        struct timeval timenow;
        struct rtentry *rtrele = NULL;

        if (rt != NULL) {
                RT_LOCK_SPIN(rt);
                RT_ADDREF_LOCKED(rt);
        }

        if (IN6_IS_ADDR_MULTICAST(&dst->sin6_addr) || !nd6_need_cache(ifp)) {
                if (rt != NULL)
                        RT_UNLOCK(rt);
                goto sendpkt;
        }

        /*
         * Next hop determination.  Because we may involve the gateway route
         * in addition to the original route, locking is rather complicated.
         * The general concept is that regardless of whether the route points
         * to the original route or to the gateway route, this routine takes
         * an extra reference on such a route.  This extra reference will be
         * released at the end.
         *
         * Care must be taken to ensure that the "hint0" route never gets freed
         * via rtfree(), since the caller may have stored it inside a struct
         * route with a reference held for that placeholder.
         *
         * This logic is similar to, though not exactly the same as the one
         * used by arp_route_to_gateway_route().
         */
        if (rt != NULL) {
                /*
                 * We have a reference to "rt" by now (or below via rtalloc1),
                 * which will either be released or freed at the end of this
                 * routine.
                 */
                RT_LOCK_ASSERT_HELD(rt);
                if (!(rt->rt_flags & RTF_UP)) {
                        RT_REMREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                        if ((hint = rt = rtalloc1((struct sockaddr *)dst,
                            1, 0)) != NULL) {
                                RT_LOCK_SPIN(rt);
                                if (rt->rt_ifp != ifp) {
                                        /* XXX: loop care? */
                                        RT_UNLOCK(rt);
                                        error = nd6_output(ifp, origifp, m0,
                                            dst, rt, locked);
                                        rtfree(rt);
                                        return (error);
                                }
                        } else {
                                senderr(EHOSTUNREACH);
                        }
                }

                if (rt->rt_flags & RTF_GATEWAY) {
                        struct rtentry *gwrt;
                        struct in6_ifaddr *ia6 = NULL;
                        struct sockaddr_in6 gw6;

                        gw6 = *((struct sockaddr_in6 *)rt->rt_gateway);
                        /*
                         * Must drop rt_lock since nd6_is_addr_neighbor()
                         * calls nd6_lookup() and acquires rnh_lock.
                         */
                        RT_UNLOCK(rt);

                        /*
                         * 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, 0) ||
                            (ia6 = 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 (ia6 != NULL)
                                        ifafree(&ia6->ia_ifa);
                                if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                                        senderr(EHOSTUNREACH);
                                goto sendpkt;
                        }

                        RT_LOCK_SPIN(rt);
                        gw6 = *((struct sockaddr_in6 *)rt->rt_gateway);

                        /* If hint is now down, give up */
                        if (!(rt->rt_flags & RTF_UP)) {
                                RT_UNLOCK(rt);
                                senderr(EHOSTUNREACH);
                        }

                        /* If there's no gateway route, look it up */
                        if ((gwrt = rt->rt_gwroute) == NULL) {
                                RT_UNLOCK(rt);
                                goto lookup;
                        }
                        /* Become a regular mutex */
                        RT_CONVERT_LOCK(rt);

                        /*
                         * Take gwrt's lock while holding route's lock;
                         * this is okay since gwrt never points back
                         * to rt, so no lock ordering issues.
                         */
                        RT_LOCK_SPIN(gwrt);
                        if (!(gwrt->rt_flags & RTF_UP)) {
                                struct rtentry *ogwrt;

                                rt->rt_gwroute = NULL;
                                RT_UNLOCK(gwrt);
                                RT_UNLOCK(rt);
                                rtfree(gwrt);
lookup:
                                gwrt = rtalloc1((struct sockaddr *)&gw6, 1, 0);

                                RT_LOCK(rt);
                                /*
                                 * Bail out if the route is down, no route
                                 * to gateway, circular route, or if the
                                 * gateway portion of "rt" has changed.
                                 */
                                if (!(rt->rt_flags & RTF_UP) ||
                                    gwrt == NULL || gwrt == rt ||
                                    !equal(SA(&gw6), rt->rt_gateway)) {
                                        if (gwrt == rt) {
                                                RT_REMREF_LOCKED(gwrt);
                                                gwrt = NULL;
                                        }
                                        RT_UNLOCK(rt);
                                        if (gwrt != NULL)
                                                rtfree(gwrt);
                                        senderr(EHOSTUNREACH);
                                }

                                /* Remove any existing gwrt */
                                ogwrt = rt->rt_gwroute;
                                if ((rt->rt_gwroute = gwrt) != NULL)
                                        RT_ADDREF(gwrt);

                                RT_UNLOCK(rt);
                                /* Now free the replaced gwrt */
                                if (ogwrt != NULL)
                                        rtfree(ogwrt);
                                /* If still no route to gateway, bail out */
                                if (gwrt == NULL)
                                        senderr(EHOSTUNREACH);
                                /* Remember to release/free "rt" at the end */
                                rtrele = rt;
                                rt = gwrt;
                                RT_LOCK_SPIN(rt);
                                /* If gwrt is now down, give up */
                                if (!(rt->rt_flags & RTF_UP)) {
                                        RT_UNLOCK(rt);
                                        rtfree(rt);
                                        rt = NULL;
                                        /* "rtrele" == original "rt" */
                                        senderr(EHOSTUNREACH);
                                }
                        } else {
                                RT_ADDREF_LOCKED(gwrt);
                                RT_UNLOCK(gwrt);
                                RT_UNLOCK(rt);
                                RT_LOCK_SPIN(gwrt);
                                /* If gwrt is now down, give up */
                                if (!(gwrt->rt_flags & RTF_UP)) {
                                        RT_UNLOCK(gwrt);
                                        rtfree(gwrt);
                                        senderr(EHOSTUNREACH);
                                }
                                /* Remember to release/free "rt" at the end */
                                rtrele = rt;
                                rt = gwrt;
                        }
                }
                /* Become a regular mutex */
                RT_CONVERT_LOCK(rt);
        }

        if (rt != NULL)
                RT_LOCK_ASSERT_HELD(rt);

        /*
         * 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 && (rt->rt_flags & RTF_LLINFO) != 0) {
                ln = 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.
                 * Must drop rt_lock since nd6_is_addr_neighbor() calls
                 * nd6_lookup() and acquires rnh_lock.
                 */
                if (rt != NULL)
                        RT_UNLOCK(rt);
                if (nd6_is_addr_neighbor(dst, ifp, 0)) {
                        /* "rtrele" may have been used, so clean up "rt" now */
                        if (rt != NULL) {
                                /* Don't free "hint0" */
                                if (rt == hint0)
                                        RT_REMREF(rt);
                                else
                                        rtfree(rt);
                        }
                        /* Callee returns a locked route upon success */
                        rt = nd6_lookup(&dst->sin6_addr, 1, ifp, 0);
                        if (rt != NULL) {
                                RT_LOCK_ASSERT_HELD(rt);
                                ln = rt->rt_llinfo;
                        }
                } else if (rt != NULL) {
                        RT_LOCK(rt);
                }
        }

        if (!ln || !rt) {
                if (rt != NULL)
                        RT_UNLOCK(rt);
                lck_rw_lock_shared(nd_if_rwlock);
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0 &&
                    !(nd_ifinfo[ifp->if_index].flags & ND6_IFF_PERFORMNUD)) {
                        lck_rw_done(nd_if_rwlock);
                        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? */
                }
                lck_rw_done(nd_if_rwlock);

                goto sendpkt;   /* send anyway */
        }

        getmicrotime(&timenow);

        /* 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;
                ln->ln_expire = rt_expiry(rt, timenow.tv_sec, nd6_gctimer);
        }

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

        /*
         * 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) {
                RT_UNLOCK(rt);
                /*
                 * Move this entry to the head of the queue so that it is
                 * less likely for this entry to be a target of forced
                 * garbage collection (see nd6_rtrequest()).
                 */
                lck_mtx_lock(rnh_lock);
                RT_LOCK_SPIN(rt);
                if (ln->ln_flags & ND6_LNF_IN_USE) {
                        LN_DEQUEUE(ln);
                        LN_INSERTHEAD(ln);
                }
                RT_UNLOCK(rt);
                lck_mtx_unlock(rnh_lock);
                goto sendpkt;
        }

        /*
         * There is a neighbor cache entry, but no ethernet address
         * response yet.  Replace the held mbuf (if any) with this
         * latest one.
         *
         * This code conforms to the rate-limiting rule described in Section
         * 7.2.2 of RFC 2461, because the timer is set correctly after sending
         * an NS below.
         */
        if (ln->ln_state == ND6_LLINFO_NOSTATE)
                ln->ln_state = ND6_LLINFO_INCOMPLETE;
        if (ln->ln_hold)
                m_freem(ln->ln_hold);
        ln->ln_hold = m;
        if (ln->ln_expire && ln->ln_asked < nd6_mmaxtries &&
            ln->ln_expire < timenow.tv_sec) {
                ln->ln_asked++;
                lck_rw_lock_shared(nd_if_rwlock);
                ln->ln_expire = timenow.tv_sec +
                        nd_ifinfo[ifp->if_index].retrans / 1000;
                lck_rw_done(nd_if_rwlock);
                RT_UNLOCK(rt);
                /* We still have a reference on rt (for ln) */
                nd6_ns_output(ifp, NULL, &dst->sin6_addr, ln, 0, locked);
        } else {
                RT_UNLOCK(rt);
        }
        /*
         * Move this entry to the head of the queue so that it is
         * less likely for this entry to be a target of forced
         * garbage collection (see nd6_rtrequest()).
         */
        lck_mtx_lock(rnh_lock);
        RT_LOCK_SPIN(rt);
        if (ln->ln_flags & ND6_LNF_IN_USE) {
                LN_DEQUEUE(ln);
                LN_INSERTHEAD(ln);
        }
        /* Clean up "rt" now while we can */
        if (rt == hint0) {
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
        } else {
                RT_UNLOCK(rt);
                rtfree_locked(rt);
        }
        rt = NULL;      /* "rt" has been taken care of */
        lck_mtx_unlock(rnh_lock);

        error = 0;
        goto release;

sendpkt:
        if (rt != NULL)
                RT_LOCK_ASSERT_NOTHELD(rt);

        /* Clean up HW checksum flags before sending the packet */
        m->m_pkthdr.csum_data = 0;
        m->m_pkthdr.csum_flags = 0;

        if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                /* forwarding rules require the original scope_id */
                m->m_pkthdr.rcvif = origifp;
                if (locked)
                        lck_mtx_unlock(ip6_mutex);
                error = dlil_output(origifp, PF_INET6, m, (caddr_t)rt,
                    (struct sockaddr *)dst, 0);
                if (locked)
                        lck_mtx_lock(ip6_mutex);
                goto release;
        } else {
                /* Do not allow loopback address to wind up on a wire */
                struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);

                if ((IN6_IS_ADDR_LOOPBACK(&ip6->ip6_src) ||
                        IN6_IS_ADDR_LOOPBACK(&ip6->ip6_dst))) {
                        ip6stat.ip6s_badscope++;
                        /*
                         * Do not simply drop the packet just like a
                         * firewall -- we want the the application to feel
                         * the pain.  Return ENETUNREACH like ip6_output
                         * does in some similar cases.  This can startle
                         * the otherwise clueless process that specifies
                         * loopback as the source address.
                         */
                        error = ENETUNREACH;
                        goto bad;
                }
        }

        m->m_pkthdr.rcvif = NULL;
        if (locked)
                lck_mtx_unlock(ip6_mutex);
        error = dlil_output(ifp, PF_INET6, m, (caddr_t)rt,
            (struct sockaddr *)dst, 0);
        if (locked)
                lck_mtx_lock(ip6_mutex);
        goto release;

bad:
        if (m != NULL)
                m_freem(m);

release:
        /* Clean up "rt" unless it's already been done */
        if (rt != NULL) {
                RT_LOCK_SPIN(rt);
                if (rt == hint0) {
                        RT_REMREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                } else {
                        RT_UNLOCK(rt);
                        rtfree(rt);
                }
        }
        /* And now clean up "rtrele" if there is any */
        if (rtrele != NULL) {
                RT_LOCK_SPIN(rtrele);
                if (rtrele == hint0) {
                        RT_REMREF_LOCKED(rtrele);
                        RT_UNLOCK(rtrele);
                } else {
                        RT_UNLOCK(rtrele);
                        rtfree(rtrele);
                }
        }
        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_L2VLAN:
        case IFT_IEEE8023ADLAG:
#if IFT_IEEE80211
        case IFT_IEEE80211:
#endif
        case IFT_BRIDGE:
        case IFT_GIF:           /* XXX need more cases? */
                return(1);
        default:
                return(0);
        }
}

int
nd6_storelladdr(
        struct ifnet *ifp,
        struct rtentry *rt,
        struct mbuf *m,
        struct sockaddr *dst,
        u_char *desten)
{
        int i;
        struct sockaddr_dl *sdl;

        if (m->m_flags & M_MCAST) {
                switch (ifp->if_type) {
                case IFT_ETHER:
                case IFT_FDDI:
                case IFT_L2VLAN:
                case IFT_IEEE8023ADLAG:
#if IFT_IEEE80211
                case IFT_IEEE80211:
#endif
                case IFT_BRIDGE:
                        ETHER_MAP_IPV6_MULTICAST(&SIN6(dst)->sin6_addr,
                                                 desten);
                        return(1);
                case IFT_IEEE1394:
                        for (i = 0; i < ifp->if_addrlen; i++)
                                desten[i] = ~0;
                        return(1);
                case IFT_ARCNET:
                        *desten = 0;
                        return(1);
                default:
                        return(0); /* caller will free mbuf */
                }
        }

        if (rt == NULL) {
                /* this could happen, if we could not allocate memory */
                return(0); /* caller will free mbuf */
        }
        RT_LOCK(rt);
        if (rt->rt_gateway->sa_family != AF_LINK) {
                printf("nd6_storelladdr: something odd happens\n");
                RT_UNLOCK(rt);
                return(0); /* caller will free mbuf */
        }
        sdl = SDL(rt->rt_gateway);
        if (sdl->sdl_alen == 0) {
                /* this should be impossible, but we bark here for debugging */
                printf("nd6_storelladdr: sdl_alen == 0\n");
                RT_UNLOCK(rt);
                return(0); /* caller will free mbuf */
        }

        bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
        RT_UNLOCK(rt);
        return(1);
}

/*
 * This is the ND pre-output routine; care must be taken to ensure that
 * the "hint" route never gets freed via rtfree(), since the caller may
 * have stored it inside a struct route with a reference held for that
 * placeholder.
 */
errno_t
nd6_lookup_ipv6(ifnet_t  ifp, const struct sockaddr_in6 *ip6_dest,
    struct sockaddr_dl *ll_dest, size_t ll_dest_len, route_t hint,
    mbuf_t packet)
{
        route_t route = hint;
        errno_t result = 0;
        struct sockaddr_dl *sdl = NULL;
        size_t  copy_len;

        if (ip6_dest->sin6_family != AF_INET6)
                return (EAFNOSUPPORT);

        if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
                return (ENETDOWN);

        if (hint != NULL) {
                /*
                 * Callee holds a reference on the route and returns
                 * with the route entry locked, upon success.
                 */
                result = arp_route_to_gateway_route(
                    (const struct sockaddr*)ip6_dest, hint, &route);
                if (result != 0)
                        return (result);
                if (route != NULL)
                        RT_LOCK_ASSERT_HELD(route);
        }

        if ((packet->m_flags & M_MCAST) != 0) {
                if (route != NULL)
                        RT_UNLOCK(route);
                result = dlil_resolve_multi(ifp,
                    (const struct sockaddr*)ip6_dest,
                    (struct sockaddr *)ll_dest, ll_dest_len);
                if (route != NULL)
                        RT_LOCK(route);
                goto release;
        }

        if (route == NULL) {
                /*
                 * This could happen, if we could not allocate memory or
                 * if arp_route_to_gateway_route() didn't return a route.
                 */
                result = ENOBUFS;
                goto release;
        }

        if (route->rt_gateway->sa_family != AF_LINK) {
                printf("nd6_lookup_ipv6: gateway address not AF_LINK\n");
                result = EADDRNOTAVAIL;
                goto release;
        }

        sdl = SDL(route->rt_gateway);
        if (sdl->sdl_alen == 0) {
                /* this should be impossible, but we bark here for debugging */
                printf("nd6_lookup_ipv6: sdl_alen == 0\n");
                result = EHOSTUNREACH;
                goto release;
        }

        copy_len = sdl->sdl_len <= ll_dest_len ? sdl->sdl_len : ll_dest_len;
        bcopy(sdl, ll_dest, copy_len);

release:
        if (route != NULL) {
                if (route == hint) {
                        RT_REMREF_LOCKED(route);
                        RT_UNLOCK(route);
                } else {
                        RT_UNLOCK(route);
                        rtfree(route);
                }
        }
        return (result);
}

SYSCTL_DECL(_net_inet6_icmp6);

static int
nd6_sysctl_drlist SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error = 0;
        char buf[1024];
        struct nd_defrouter *dr;
        int p64 = proc_is64bit(req->p);

        if (req->newptr)
                return (EPERM);

        lck_mtx_lock(nd6_mutex);
        if (p64) {
                struct in6_defrouter_64 *d, *de;

                for (dr = TAILQ_FIRST(&nd_defrouter);
                     dr;
                     dr = TAILQ_NEXT(dr, dr_entry)) {
                        d = (struct in6_defrouter_64 *)buf;
                        de = (struct in6_defrouter_64 *)(buf + sizeof (buf));

                        if (d + 1 <= de) {
                                bzero(d, sizeof (*d));
                                d->rtaddr.sin6_family = AF_INET6;
                                d->rtaddr.sin6_len = sizeof (d->rtaddr);
                                if (in6_recoverscope(&d->rtaddr, &dr->rtaddr,
                                    dr->ifp) != 0)
                                        log(LOG_ERR,
                                            "scope error in "
                                            "default router list (%s)\n",
                                            ip6_sprintf(&dr->rtaddr));
                                d->flags = dr->flags;
                                d->rtlifetime = dr->rtlifetime;
                                d->expire = dr->expire;
                                d->if_index = dr->ifp->if_index;
                        } else {
                                panic("buffer too short");
                        }
                        error = SYSCTL_OUT(req, buf, sizeof (*d));
                        if (error)
                                break;
                }
        } else {
                struct in6_defrouter_32 *d_32, *de_32;

                for (dr = TAILQ_FIRST(&nd_defrouter);
                     dr;
                     dr = TAILQ_NEXT(dr, dr_entry)) {
                        d_32 = (struct in6_defrouter_32 *)buf;
                        de_32 = (struct in6_defrouter_32 *)(buf + sizeof (buf));

                        if (d_32 + 1 <= de_32) {
                                bzero(d_32, sizeof (*d_32));
                                d_32->rtaddr.sin6_family = AF_INET6;
                                d_32->rtaddr.sin6_len = sizeof (d_32->rtaddr);
                                if (in6_recoverscope(&d_32->rtaddr, &dr->rtaddr,
                                    dr->ifp) != 0)
                                        log(LOG_ERR,
                                            "scope error in "
                                            "default router list (%s)\n",
                                            ip6_sprintf(&dr->rtaddr));
                                d_32->flags = dr->flags;
                                d_32->rtlifetime = dr->rtlifetime;
                                d_32->expire = dr->expire;
                                d_32->if_index = dr->ifp->if_index;
                        } else {
                                panic("buffer too short");
                        }
                        error = SYSCTL_OUT(req, buf, sizeof (*d_32));
                        if (error)
                                break;
                }
        }
        lck_mtx_unlock(nd6_mutex);
        return (error);
}

static int
nd6_sysctl_prlist SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error = 0;
        char buf[1024];
        struct nd_prefix *pr;
        int p64 = proc_is64bit(req->p);

        if (req->newptr)
                return (EPERM);

        lck_mtx_lock(nd6_mutex);
        if (p64) {
                struct in6_prefix_64 *p, *pe;

                for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
                        u_short advrtrs = 0;
                        size_t advance;
                        struct sockaddr_in6 *sin6, *s6;
                        struct nd_pfxrouter *pfr;

                        p = (struct in6_prefix_64 *)buf;
                        pe = (struct in6_prefix_64 *)(buf + sizeof (buf));

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

                                p->prefix = pr->ndpr_prefix;
                                if (in6_recoverscope(&p->prefix,
                                    &p->prefix.sin6_addr, pr->ndpr_ifp) != 0)
                                        log(LOG_ERR,
                                            "scope error in prefix list (%s)\n",
                                            ip6_sprintf(&p->prefix.sin6_addr));
                                p->raflags = pr->ndpr_raf;
                                p->prefixlen = pr->ndpr_plen;
                                p->vltime = pr->ndpr_vltime;
                                p->pltime = pr->ndpr_pltime;
                                p->if_index = pr->ndpr_ifp->if_index;
                                p->expire = pr->ndpr_expire;
                                p->refcnt = pr->ndpr_refcnt;
                                p->flags = pr->ndpr_stateflags;
                                p->origin = PR_ORIG_RA;
                                advrtrs = 0;
                                for (pfr = pr->ndpr_advrtrs.lh_first;
                                     pfr;
                                     pfr = pfr->pfr_next) {
                                        if ((void *)&sin6[advrtrs + 1] >
                                            (void *)pe) {
                                                advrtrs++;
                                                continue;
                                        }
                                        s6 = &sin6[advrtrs];
                                        bzero(s6, sizeof (*s6));
                                        s6->sin6_family = AF_INET6;
                                        s6->sin6_len = sizeof (*sin6);
                                        if (in6_recoverscope(s6,
                                            &pfr->router->rtaddr,
                                            pfr->router->ifp) != 0)
                                                log(LOG_ERR, "scope error in "
                                                    "prefix list (%s)\n",
                                                    ip6_sprintf(&pfr->router->
                                                    rtaddr));
                                        advrtrs++;
                                }
                                p->advrtrs = advrtrs;
                        } else {
                                panic("buffer too short");
                        }
                        advance = sizeof (*p) + sizeof (*sin6) * advrtrs;
                        error = SYSCTL_OUT(req, buf, advance);
                        if (error)
                                break;
                }
        } else {
                struct in6_prefix_32 *p_32, *pe_32;

                for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
                        u_short advrtrs = 0;
                        size_t advance;
                        struct sockaddr_in6 *sin6, *s6;
                        struct nd_pfxrouter *pfr;

                        p_32 = (struct in6_prefix_32 *)buf;
                        pe_32 = (struct in6_prefix_32 *)(buf + sizeof (buf));

                        if (p_32 + 1 <= pe_32) {
                                bzero(p_32, sizeof (*p_32));
                                sin6 = (struct sockaddr_in6 *)(p_32 + 1);

                                p_32->prefix = pr->ndpr_prefix;
                                if (in6_recoverscope(&p_32->prefix,
                                    &p_32->prefix.sin6_addr, pr->ndpr_ifp) != 0)
                                        log(LOG_ERR, "scope error in prefix "
                                            "list (%s)\n", ip6_sprintf(&p_32->
                                            prefix.sin6_addr));
                                p_32->raflags = pr->ndpr_raf;
                                p_32->prefixlen = pr->ndpr_plen;
                                p_32->vltime = pr->ndpr_vltime;
                                p_32->pltime = pr->ndpr_pltime;
                                p_32->if_index = pr->ndpr_ifp->if_index;
                                p_32->expire = pr->ndpr_expire;
                                p_32->refcnt = pr->ndpr_refcnt;
                                p_32->flags = pr->ndpr_stateflags;
                                p_32->origin = PR_ORIG_RA;
                                advrtrs = 0;
                                for (pfr = pr->ndpr_advrtrs.lh_first;
                                     pfr;
                                     pfr = pfr->pfr_next) {
                                        if ((void *)&sin6[advrtrs + 1] >
                                            (void *)pe_32) {
                                                advrtrs++;
                                                continue;
                                        }
                                        s6 = &sin6[advrtrs];
                                        bzero(s6, sizeof (*s6));
                                        s6->sin6_family = AF_INET6;
                                        s6->sin6_len = sizeof (*sin6);
                                        if (in6_recoverscope(s6,
                                            &pfr->router->rtaddr,
                                            pfr->router->ifp) != 0)
                                                log(LOG_ERR, "scope error in "
                                                    "prefix list (%s)\n",
                                                    ip6_sprintf(&pfr->router->
                                                    rtaddr));
                                        advrtrs++;
                                }
                                p_32->advrtrs = advrtrs;
                        } else {
                                panic("buffer too short");
                        }
                        advance = sizeof (*p_32) + sizeof (*sin6) * advrtrs;
                        error = SYSCTL_OUT(req, buf, advance);
                        if (error)
                                break;
                }
        }
        lck_mtx_unlock(nd6_mutex);
        return (error);
}
SYSCTL_PROC(_net_inet6_icmp6, ICMPV6CTL_ND6_DRLIST, nd6_drlist,
        CTLFLAG_RD, 0, 0, nd6_sysctl_drlist, "S,in6_defrouter","");
SYSCTL_PROC(_net_inet6_icmp6, ICMPV6CTL_ND6_PRLIST, nd6_prlist,
        CTLFLAG_RD, 0, 0, nd6_sysctl_prlist, "S,in6_defrouter","");