Make clock_gettime() and clock_getres() work for CloudABI programs.

[FreeBSD/FreeBSD.git] / sys / netinet6 / nd6.c

/*-
 * 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.
 *
 *      $KAME: nd6.c,v 1.144 2001/05/24 07:44:00 itojun Exp $
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

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

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

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_arc.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/iso88025.h>
#include <net/fddi.h>
#include <net/route.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <net/if_llatbl.h>
#define L3_ADDR_SIN6(le)        ((struct sockaddr_in6 *) L3_ADDR(le))
#include <netinet/if_ether.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_ifattach.h>
#include <netinet/icmp6.h>
#include <netinet6/send.h>

#include <sys/limits.h>

#include <security/mac/mac_framework.h>

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

#define SIN6(s) ((const struct sockaddr_in6 *)(s))

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

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

VNET_DEFINE(int, nd6_maxnudhint) = 0;   /* max # of subsequent upper
                                         * layer hints */
static VNET_DEFINE(int, nd6_maxqueuelen) = 1; /* max pkts cached in unresolved
                                         * ND entries */
#define V_nd6_maxndopt                  VNET(nd6_maxndopt)
#define V_nd6_maxqueuelen               VNET(nd6_maxqueuelen)

#ifdef ND6_DEBUG
VNET_DEFINE(int, nd6_debug) = 1;
#else
VNET_DEFINE(int, nd6_debug) = 0;
#endif

static eventhandler_tag lle_event_eh;

/* for debugging? */
#if 0
static int nd6_inuse, nd6_allocated;
#endif

VNET_DEFINE(struct nd_drhead, nd_defrouter);
VNET_DEFINE(struct nd_prhead, nd_prefix);

VNET_DEFINE(int, nd6_recalc_reachtm_interval) = ND6_RECALC_REACHTM_INTERVAL;
#define V_nd6_recalc_reachtm_interval   VNET(nd6_recalc_reachtm_interval)

int     (*send_sendso_input_hook)(struct mbuf *, struct ifnet *, int, int);

static int nd6_is_new_addr_neighbor(struct sockaddr_in6 *,
        struct ifnet *);
static void nd6_setmtu0(struct ifnet *, struct nd_ifinfo *);
static void nd6_slowtimo(void *);
static int regen_tmpaddr(struct in6_ifaddr *);
static struct llentry *nd6_free(struct llentry *, int);
static void nd6_llinfo_timer(void *);
static void clear_llinfo_pqueue(struct llentry *);
static void nd6_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
static int nd6_output_lle(struct ifnet *, struct ifnet *, struct mbuf *,
        struct sockaddr_in6 *);
static int nd6_output_ifp(struct ifnet *, struct ifnet *, struct mbuf *,
    struct sockaddr_in6 *);

static VNET_DEFINE(struct callout, nd6_slowtimo_ch);
#define V_nd6_slowtimo_ch               VNET(nd6_slowtimo_ch)

VNET_DEFINE(struct callout, nd6_timer_ch);

static void
nd6_lle_event(void *arg __unused, struct llentry *lle, int evt)
{
        struct rt_addrinfo rtinfo;
        struct sockaddr_in6 dst, *sa6;
        struct sockaddr_dl gw;
        struct ifnet *ifp;
        int type;

        LLE_WLOCK_ASSERT(lle);

        switch (evt) {
        case LLENTRY_RESOLVED:
                type = RTM_ADD;
                KASSERT(lle->la_flags & LLE_VALID,
                    ("%s: %p resolved but not valid?", __func__, lle));
                break;
        case LLENTRY_EXPIRED:
                type = RTM_DELETE;
                break;
        default:
                return;
        }

        sa6 = L3_ADDR_SIN6(lle);
        if (sa6->sin6_family != AF_INET6)
                return;
        ifp = lle->lle_tbl->llt_ifp;

        bzero(&dst, sizeof(dst));
        bzero(&gw, sizeof(gw));
        bzero(&rtinfo, sizeof(rtinfo));
        dst.sin6_len = sizeof(struct sockaddr_in6);
        dst.sin6_family = AF_INET6;
        dst.sin6_addr = sa6->sin6_addr;
        dst.sin6_scope_id = in6_getscopezone(ifp,
            in6_addrscope(&sa6->sin6_addr));
        in6_clearscope(&dst.sin6_addr); /* XXX */
        gw.sdl_len = sizeof(struct sockaddr_dl);
        gw.sdl_family = AF_LINK;
        gw.sdl_alen = ifp->if_addrlen;
        gw.sdl_index = ifp->if_index;
        gw.sdl_type = ifp->if_type;
        if (evt == LLENTRY_RESOLVED)
                bcopy(&lle->ll_addr, gw.sdl_data, ifp->if_addrlen);
        rtinfo.rti_info[RTAX_DST] = (struct sockaddr *)&dst;
        rtinfo.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&gw;
        rtinfo.rti_addrs = RTA_DST | RTA_GATEWAY;
        rt_missmsg_fib(type, &rtinfo, RTF_HOST | RTF_LLDATA | (
            type == RTM_ADD ? RTF_UP: 0), 0, RT_DEFAULT_FIB);
}

void
nd6_init(void)
{

        LIST_INIT(&V_nd_prefix);

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

        /* start timer */
        callout_init(&V_nd6_slowtimo_ch, 0);
        callout_reset(&V_nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
            nd6_slowtimo, curvnet);

        nd6_dad_init();
        if (IS_DEFAULT_VNET(curvnet))
                lle_event_eh = EVENTHANDLER_REGISTER(lle_event, nd6_lle_event,
                    NULL, EVENTHANDLER_PRI_ANY);
}

#ifdef VIMAGE
void
nd6_destroy()
{

        callout_drain(&V_nd6_slowtimo_ch);
        callout_drain(&V_nd6_timer_ch);
        if (IS_DEFAULT_VNET(curvnet))
                EVENTHANDLER_DEREGISTER(lle_event, lle_event_eh);
}
#endif

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

        nd = (struct nd_ifinfo *)malloc(sizeof(*nd), M_IP6NDP, M_WAITOK|M_ZERO);
        nd->initialized = 1;

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

        nd->flags = ND6_IFF_PERFORMNUD;

        /* A loopback interface always has ND6_IFF_AUTO_LINKLOCAL.
         * XXXHRS: Clear ND6_IFF_AUTO_LINKLOCAL on an IFT_BRIDGE interface by
         * default regardless of the V_ip6_auto_linklocal configuration to
         * give a reasonable default behavior.
         */
        if ((V_ip6_auto_linklocal && ifp->if_type != IFT_BRIDGE) ||
            (ifp->if_flags & IFF_LOOPBACK))
                nd->flags |= ND6_IFF_AUTO_LINKLOCAL;
        /*
         * A loopback interface does not need to accept RTADV.
         * XXXHRS: Clear ND6_IFF_ACCEPT_RTADV on an IFT_BRIDGE interface by
         * default regardless of the V_ip6_accept_rtadv configuration to
         * prevent the interface from accepting RA messages arrived
         * on one of the member interfaces with ND6_IFF_ACCEPT_RTADV.
         */
        if (V_ip6_accept_rtadv &&
            !(ifp->if_flags & IFF_LOOPBACK) &&
            (ifp->if_type != IFT_BRIDGE))
                        nd->flags |= ND6_IFF_ACCEPT_RTADV;
        if (V_ip6_no_radr && !(ifp->if_flags & IFF_LOOPBACK))
                nd->flags |= ND6_IFF_NO_RADR;

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

        return nd;
}

void
nd6_ifdetach(struct nd_ifinfo *nd)
{

        free(nd, M_IP6NDP);
}

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

        nd6_setmtu0(ifp, ND_IFINFO(ifp));
}

/* XXX todo: do not maintain copy of ifp->if_mtu in ndi->maxmtu */
void
nd6_setmtu0(struct ifnet *ifp, struct nd_ifinfo *ndi)
{
        u_int32_t omaxmtu;

        omaxmtu = ndi->maxmtu;

        switch (ifp->if_type) {
        case IFT_ARCNET:
                ndi->maxmtu = MIN(ARC_PHDS_MAXMTU, ifp->if_mtu); /* RFC2497 */
                break;
        case IFT_FDDI:
                ndi->maxmtu = MIN(FDDIIPMTU, ifp->if_mtu); /* RFC2467 */
                break;
        case IFT_ISO88025:
                 ndi->maxmtu = MIN(ISO88025_MAX_MTU, ifp->if_mtu);
                 break;
        default:
                ndi->maxmtu = ifp->if_mtu;
                break;
        }

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

        if (ndi->maxmtu > V_in6_maxmtu)
                in6_setmaxmtu(); /* check all interfaces just in case */

}

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;

        KASSERT(ndopts != NULL, ("%s: ndopts == NULL", __func__));
        KASSERT(ndopts->nd_opts_last != NULL, ("%s: uninitialized ndopts",
            __func__));
        if (ndopts->nd_opts_search == NULL)
                return NULL;
        if (ndopts->nd_opts_done)
                return NULL;

        nd_opt = ndopts->nd_opts_search;

        /* make sure nd_opt_len is inside the buffer */
        if ((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;

        KASSERT(ndopts != NULL, ("%s: ndopts == NULL", __func__));
        KASSERT(ndopts->nd_opts_last != NULL, ("%s: uninitialized ndopts",
            __func__));
        if (ndopts->nd_opts_search == NULL)
                return 0;

        while (1) {
                nd_opt = nd6_option(ndopts);
                if (nd_opt == NULL && ndopts->nd_opts_last == NULL) {
                        /*
                         * Message validation requires that all included
                         * options have a length that is greater than zero.
                         */
                        ICMP6STAT_INC(icp6s_nd_badopt);
                        bzero(ndopts, sizeof(*ndopts));
                        return -1;
                }

                if (nd_opt == NULL)
                        goto skip1;

                switch (nd_opt->nd_opt_type) {
                case ND_OPT_SOURCE_LINKADDR:
                case ND_OPT_TARGET_LINKADDR:
                case ND_OPT_MTU:
                case ND_OPT_REDIRECTED_HEADER:
                case ND_OPT_NONCE:
                        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;
                /* What about ND_OPT_ROUTE_INFO? RFC 4191 */
                case ND_OPT_RDNSS:      /* RFC 6106 */
                case ND_OPT_DNSSL:      /* RFC 6106 */
                        /*
                         * Silently ignore options we know and do not care about
                         * in the kernel.
                         */
                        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 > V_nd6_maxndopt) {
                        ICMP6STAT_INC(icp6s_nd_toomanyopt);
                        nd6log((LOG_INFO, "too many loop in nd opt\n"));
                        break;
                }

                if (ndopts->nd_opts_done)
                        break;
        }

        return 0;
}

/*
 * ND6 timer routine to handle ND6 entries
 */
void
nd6_llinfo_settimer_locked(struct llentry *ln, long tick)
{
        int canceled;

        LLE_WLOCK_ASSERT(ln);

        if (tick < 0) {
                ln->la_expire = 0;
                ln->ln_ntick = 0;
                canceled = callout_stop(&ln->ln_timer_ch);
        } else {
                ln->la_expire = time_uptime + tick / hz;
                LLE_ADDREF(ln);
                if (tick > INT_MAX) {
                        ln->ln_ntick = tick - INT_MAX;
                        canceled = callout_reset(&ln->ln_timer_ch, INT_MAX,
                            nd6_llinfo_timer, ln);
                } else {
                        ln->ln_ntick = 0;
                        canceled = callout_reset(&ln->ln_timer_ch, tick,
                            nd6_llinfo_timer, ln);
                }
        }
        if (canceled)
                LLE_REMREF(ln);
}

void
nd6_llinfo_settimer(struct llentry *ln, long tick)
{

        LLE_WLOCK(ln);
        nd6_llinfo_settimer_locked(ln, tick);
        LLE_WUNLOCK(ln);
}

static void
nd6_llinfo_timer(void *arg)
{
        struct llentry *ln;
        struct in6_addr *dst;
        struct ifnet *ifp;
        struct nd_ifinfo *ndi = NULL;

        KASSERT(arg != NULL, ("%s: arg NULL", __func__));
        ln = (struct llentry *)arg;
        LLE_WLOCK(ln);
        if (callout_pending(&ln->la_timer)) {
                /*
                 * Here we are a bit odd here in the treatment of 
                 * active/pending. If the pending bit is set, it got
                 * rescheduled before I ran. The active
                 * bit we ignore, since if it was stopped
                 * in ll_tablefree() and was currently running
                 * it would have return 0 so the code would
                 * not have deleted it since the callout could
                 * not be stopped so we want to go through
                 * with the delete here now. If the callout
                 * was restarted, the pending bit will be back on and
                 * we just want to bail since the callout_reset would
                 * return 1 and our reference would have been removed
                 * by nd6_llinfo_settimer_locked above since canceled
                 * would have been 1.
                 */
                LLE_WUNLOCK(ln);
                return;
        }
        ifp = ln->lle_tbl->llt_ifp;
        CURVNET_SET(ifp->if_vnet);

        if (ln->ln_ntick > 0) {
                if (ln->ln_ntick > INT_MAX) {
                        ln->ln_ntick -= INT_MAX;
                        nd6_llinfo_settimer_locked(ln, INT_MAX);
                } else {
                        ln->ln_ntick = 0;
                        nd6_llinfo_settimer_locked(ln, ln->ln_ntick);
                }
                goto done;
        }

        ndi = ND_IFINFO(ifp);
        dst = &L3_ADDR_SIN6(ln)->sin6_addr;
        if (ln->la_flags & LLE_STATIC) {
                goto done;
        }

        if (ln->la_flags & LLE_DELETED) {
                (void)nd6_free(ln, 0);
                ln = NULL;
                goto done;
        }

        switch (ln->ln_state) {
        case ND6_LLINFO_INCOMPLETE:
                if (ln->la_asked < V_nd6_mmaxtries) {
                        ln->la_asked++;
                        nd6_llinfo_settimer_locked(ln, (long)ndi->retrans * hz / 1000);
                        LLE_WUNLOCK(ln);
                        nd6_ns_output(ifp, NULL, dst, ln, NULL);
                        LLE_WLOCK(ln);
                } else {
                        struct mbuf *m = ln->la_hold;
                        if (m) {
                                struct mbuf *m0;

                                /*
                                 * assuming every packet in la_hold has the
                                 * same IP header.  Send error after unlock.
                                 */
                                m0 = m->m_nextpkt;
                                m->m_nextpkt = NULL;
                                ln->la_hold = m0;
                                clear_llinfo_pqueue(ln);
                        }
                        EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_TIMEDOUT);
                        (void)nd6_free(ln, 0);
                        ln = NULL;
                        if (m != NULL)
                                icmp6_error2(m, ICMP6_DST_UNREACH,
                                    ICMP6_DST_UNREACH_ADDR, 0, ifp);
                }
                break;
        case ND6_LLINFO_REACHABLE:
                if (!ND6_LLINFO_PERMANENT(ln)) {
                        ln->ln_state = ND6_LLINFO_STALE;
                        nd6_llinfo_settimer_locked(ln, (long)V_nd6_gctimer * hz);
                }
                break;

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

        case ND6_LLINFO_DELAY:
                if (ndi && (ndi->flags & ND6_IFF_PERFORMNUD) != 0) {
                        /* We need NUD */
                        ln->la_asked = 1;
                        ln->ln_state = ND6_LLINFO_PROBE;
                        nd6_llinfo_settimer_locked(ln, (long)ndi->retrans * hz / 1000);
                        LLE_WUNLOCK(ln);
                        nd6_ns_output(ifp, dst, dst, ln, NULL);
                        LLE_WLOCK(ln);
                } else {
                        ln->ln_state = ND6_LLINFO_STALE; /* XXX */
                        nd6_llinfo_settimer_locked(ln, (long)V_nd6_gctimer * hz);
                }
                break;
        case ND6_LLINFO_PROBE:
                if (ln->la_asked < V_nd6_umaxtries) {
                        ln->la_asked++;
                        nd6_llinfo_settimer_locked(ln, (long)ndi->retrans * hz / 1000);
                        LLE_WUNLOCK(ln);
                        nd6_ns_output(ifp, dst, dst, ln, NULL);
                        LLE_WLOCK(ln);
                } else {
                        EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_EXPIRED);
                        (void)nd6_free(ln, 0);
                        ln = NULL;
                }
                break;
        default:
                panic("%s: paths in a dark night can be confusing: %d",
                    __func__, ln->ln_state);
        }
done:
        if (ln != NULL)
                LLE_FREE_LOCKED(ln);
        CURVNET_RESTORE();
}


/*
 * ND6 timer routine to expire default route list and prefix list
 */
void
nd6_timer(void *arg)
{
        CURVNET_SET((struct vnet *) arg);
        struct nd_defrouter *dr, *ndr;
        struct nd_prefix *pr, *npr;
        struct in6_ifaddr *ia6, *nia6;

        callout_reset(&V_nd6_timer_ch, V_nd6_prune * hz,
            nd6_timer, curvnet);

        /* expire default router list */
        TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, ndr) {
                if (dr->expire && dr->expire < time_uptime)
                        defrtrlist_del(dr);
        }

        /*
         * expire interface addresses.
         * in the past the loop was inside prefix expiry processing.
         * However, from a stricter speci-confrmance standpoint, we should
         * rather separate address lifetimes and prefix lifetimes.
         *
         * XXXRW: in6_ifaddrhead locking.
         */
  addrloop:
        TAILQ_FOREACH_SAFE(ia6, &V_in6_ifaddrhead, ia_link, nia6) {
                /* check address lifetime */
                if (IFA6_IS_INVALID(ia6)) {
                        int regen = 0;

                        /*
                         * If the expiring address is temporary, try
                         * regenerating a new one.  This would be useful when
                         * we suspended a laptop PC, then turned it on after a
                         * period that could invalidate all temporary
                         * addresses.  Although we may have to restart the
                         * loop (see below), it must be after purging the
                         * address.  Otherwise, we'd see an infinite loop of
                         * regeneration.
                         */
                        if (V_ip6_use_tempaddr &&
                            (ia6->ia6_flags & IN6_IFF_TEMPORARY) != 0) {
                                if (regen_tmpaddr(ia6) == 0)
                                        regen = 1;
                        }

                        in6_purgeaddr(&ia6->ia_ifa);

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

                        ia6->ia6_flags |= IN6_IFF_DEPRECATED;

                        /*
                         * If a temporary address has just become deprecated,
                         * regenerate a new one if possible.
                         */
                        if (V_ip6_use_tempaddr &&
                            (ia6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                            (oldflags & IN6_IFF_DEPRECATED) == 0) {

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

        /* expire prefix list */
        LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, npr) {
                /*
                 * check prefix lifetime.
                 * since pltime is just for autoconf, pltime processing for
                 * prefix is not necessary.
                 */
                if (pr->ndpr_vltime != ND6_INFINITE_LIFETIME &&
                    time_uptime - pr->ndpr_lastupdate > pr->ndpr_vltime) {

                        /*
                         * address expiration and prefix expiration are
                         * separate.  NEVER perform in6_purgeaddr here.
                         */
                        prelist_remove(pr);
                }
        }
        CURVNET_RESTORE();
}

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

        ifp = ia6->ia_ifa.ifa_ifp;
        IF_ADDR_RLOCK(ifp);
        TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                struct in6_ifaddr *it6;

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

                it6 = (struct in6_ifaddr *)ifa;

                /* ignore no autoconf addresses. */
                if ((it6->ia6_flags & IN6_IFF_AUTOCONF) == 0)
                        continue;

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

                /*
                 * Now we are looking at an autoconf address with the same
                 * prefix as ours.  If the address is temporary and is still
                 * preferred, do not create another one.  It would be rare, but
                 * could happen, for example, when we resume a laptop PC after
                 * a long period.
                 */
                if ((it6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                    !IFA6_IS_DEPRECATED(it6)) {
                        public_ifa6 = NULL;
                        break;
                }

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

        if (public_ifa6 != NULL) {
                int e;

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

        return (-1);
}

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

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

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

        TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, ndr) {
                if (!dr->installed)
                        continue;

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

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

                        /*
                         * Previously, pr->ndpr_addr is removed as well,
                         * but I strongly believe we don't have to do it.
                         * nd6_purge() is only called from in6_ifdetach(),
                         * which removes all the associated interface addresses
                         * by itself.
                         * (jinmei@kame.net 20010129)
                         */
                        prelist_remove(pr);
                }
        }

        /* cancel default outgoing interface setting */
        if (V_nd6_defifindex == ifp->if_index)
                nd6_setdefaultiface(0);

        if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
                /* Refresh default router list. */
                defrouter_select();
        }

        /* XXXXX
         * We do not nuke the neighbor cache entries here any more
         * because the neighbor cache is kept in if_afdata[AF_INET6].
         * nd6_purge() is invoked by in6_ifdetach() which is called
         * from if_detach() where everything gets purged. So let
         * in6_domifdetach() do the actual L2 table purging work.
         */
}

/* 
 * the caller acquires and releases the lock on the lltbls
 * Returns the llentry locked
 */
struct llentry *
nd6_lookup(struct in6_addr *addr6, int flags, struct ifnet *ifp)
{
        struct sockaddr_in6 sin6;
        struct llentry *ln;
        int llflags;
        
        bzero(&sin6, sizeof(sin6));
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_addr = *addr6;

        IF_AFDATA_LOCK_ASSERT(ifp);

        llflags = 0;
        if (flags & ND6_CREATE)
            llflags |= LLE_CREATE;
        if (flags & ND6_EXCLUSIVE)
            llflags |= LLE_EXCLUSIVE;   
        
        ln = lla_lookup(LLTABLE6(ifp), llflags, (struct sockaddr *)&sin6);
        if ((ln != NULL) && (llflags & LLE_CREATE))
                ln->ln_state = ND6_LLINFO_NOSTATE;
        
        return (ln);
}

/*
 * Test whether a given IPv6 address is a neighbor or not, ignoring
 * the actual neighbor cache.  The neighbor cache is ignored in order
 * to not reenter the routing code from within itself.
 */
static int
nd6_is_new_addr_neighbor(struct sockaddr_in6 *addr, struct ifnet *ifp)
{
        struct nd_prefix *pr;
        struct ifaddr *dstaddr;

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

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

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

                if (!(pr->ndpr_stateflags & NDPRF_ONLINK)) {
                        struct rtentry *rt;

                        /* Always use the default FIB here. */
                        rt = in6_rtalloc1((struct sockaddr *)&pr->ndpr_prefix,
                            0, 0, RT_DEFAULT_FIB);
                        if (rt == NULL)
                                continue;
                        /*
                         * This is the case where multiple interfaces
                         * have the same prefix, but only one is installed 
                         * into the routing table and that prefix entry
                         * is not the one being examined here. In the case
                         * where RADIX_MPATH is enabled, multiple route
                         * entries (of the same rt_key value) will be 
                         * installed because the interface addresses all
                         * differ.
                         */
                        if (!IN6_ARE_ADDR_EQUAL(&pr->ndpr_prefix.sin6_addr,
                               &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr)) {
                                RTFREE_LOCKED(rt);
                                continue;
                        }
                        RTFREE_LOCKED(rt);
                }

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

        /*
         * If the address is assigned on the node of the other side of
         * a p2p interface, the address should be a neighbor.
         */
        dstaddr = ifa_ifwithdstaddr((struct sockaddr *)addr, RT_ALL_FIBS);
        if (dstaddr != NULL) {
                if (dstaddr->ifa_ifp == ifp) {
                        ifa_free(dstaddr);
                        return (1);
                }
                ifa_free(dstaddr);
        }

        /*
         * If the default router list is empty, all addresses are regarded
         * as on-link, and thus, as a neighbor.
         */
        if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV &&
            TAILQ_EMPTY(&V_nd_defrouter) &&
            V_nd6_defifindex == ifp->if_index) {
                return (1);
        }

        return (0);
}


/*
 * Detect if a given IPv6 address identifies a neighbor on a given link.
 * XXX: should take care of the destination of a p2p link?
 */
int
nd6_is_addr_neighbor(struct sockaddr_in6 *addr, struct ifnet *ifp)
{
        struct llentry *lle;
        int rc = 0;

        IF_AFDATA_UNLOCK_ASSERT(ifp);
        if (nd6_is_new_addr_neighbor(addr, ifp))
                return (1);

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

/*
 * Free an nd6 llinfo entry.
 * Since the function would cause significant changes in the kernel, DO NOT
 * make it global, unless you have a strong reason for the change, and are sure
 * that the change is safe.
 */
static struct llentry *
nd6_free(struct llentry *ln, int gc)
{
        struct llentry *next;
        struct nd_defrouter *dr;
        struct ifnet *ifp;

        LLE_WLOCK_ASSERT(ln);

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

        /* cancel timer */
        nd6_llinfo_settimer_locked(ln, -1);

        ifp = ln->lle_tbl->llt_ifp;

        if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
                dr = defrouter_lookup(&L3_ADDR_SIN6(ln)->sin6_addr, ifp);

                if (dr != NULL && dr->expire &&
                    ln->ln_state == ND6_LLINFO_STALE && gc) {
                        /*
                         * If the reason for the deletion is just garbage
                         * collection, and the neighbor is an active default
                         * router, do not delete it.  Instead, reset the GC
                         * timer using the router's lifetime.
                         * Simply deleting the entry would affect default
                         * router selection, which is not necessarily a good
                         * thing, especially when we're using router preference
                         * values.
                         * XXX: the check for ln_state would be redundant,
                         *      but we intentionally keep it just in case.
                         */
                        if (dr->expire > time_uptime)
                                nd6_llinfo_settimer_locked(ln,
                                    (dr->expire - time_uptime) * hz);
                        else
                                nd6_llinfo_settimer_locked(ln,
                                    (long)V_nd6_gctimer * hz);

                        next = LIST_NEXT(ln, lle_next);
                        LLE_REMREF(ln);
                        LLE_WUNLOCK(ln);
                        return (next);
                }

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

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

                if (ln->ln_router || dr) {

                        /*
                         * We need to unlock to avoid a LOR with rt6_flush() with the
                         * rnh and for the calls to pfxlist_onlink_check() and
                         * defrouter_select() in the block further down for calls
                         * into nd6_lookup().  We still hold a ref.
                         */
                        LLE_WUNLOCK(ln);

                        /*
                         * rt6_flush must be called whether or not the neighbor
                         * is in the Default Router List.
                         * See a corresponding comment in nd6_na_input().
                         */
                        rt6_flush(&L3_ADDR_SIN6(ln)->sin6_addr, ifp);
                }

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

                        /*
                         * Refresh default router list.
                         */
                        defrouter_select();
                }

                if (ln->ln_router || dr)
                        LLE_WLOCK(ln);
        }

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

        /*
         * Save to unlock. We still hold an extra reference and will not
         * free(9) in llentry_free() if someone else holds one as well.
         */
        LLE_WUNLOCK(ln);
        IF_AFDATA_LOCK(ifp);
        LLE_WLOCK(ln);

        /* Guard against race with other llentry_free(). */
        if (ln->la_flags & LLE_LINKED) {
                LLE_REMREF(ln);
                llentry_free(ln);
        } else
                LLE_FREE_LOCKED(ln);

        IF_AFDATA_UNLOCK(ifp);

        return (next);
}

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

        if ((dst6 == NULL) || (rt == NULL))
                return;

        ifp = rt->rt_ifp;
        IF_AFDATA_RLOCK(ifp);
        ln = nd6_lookup(dst6, ND6_EXCLUSIVE, NULL);
        IF_AFDATA_RUNLOCK(ifp);
        if (ln == NULL)
                return;

        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 > V_nd6_maxnudhint) {
                        goto done;
                }
        }

        ln->ln_state = ND6_LLINFO_REACHABLE;
        if (!ND6_LLINFO_PERMANENT(ln)) {
                nd6_llinfo_settimer_locked(ln,
                    (long)ND_IFINFO(rt->rt_ifp)->reachable * hz);
        }
done:
        LLE_WUNLOCK(ln);
}


/*
 * Rejuvenate this function for routing operations related
 * processing.
 */
void
nd6_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
{
        struct sockaddr_in6 *gateway;
        struct nd_defrouter *dr;
        struct ifnet *ifp;

        gateway = (struct sockaddr_in6 *)rt->rt_gateway;
        ifp = rt->rt_ifp;

        switch (req) {
        case RTM_ADD:
                break;

        case RTM_DELETE:
                if (!ifp)
                        return;
                /*
                 * Only indirect routes are interesting.
                 */
                if ((rt->rt_flags & RTF_GATEWAY) == 0)
                        return;
                /*
                 * check for default route
                 */
                if (IN6_ARE_ADDR_EQUAL(&in6addr_any, 
                                       &SIN6(rt_key(rt))->sin6_addr)) {

                        dr = defrouter_lookup(&gateway->sin6_addr, ifp);
                        if (dr != NULL)
                                dr->installed = 0;
                }
                break;
        }
}


int
nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
{
        struct in6_drlist *drl = (struct in6_drlist *)data;
        struct in6_oprlist *oprl = (struct in6_oprlist *)data;
        struct in6_ndireq *ndi = (struct in6_ndireq *)data;
        struct in6_nbrinfo *nbi = (struct in6_nbrinfo *)data;
        struct in6_ndifreq *ndif = (struct in6_ndifreq *)data;
        struct nd_defrouter *dr;
        struct nd_prefix *pr;
        int i = 0, error = 0;

        if (ifp->if_afdata[AF_INET6] == NULL)
                return (EPFNOSUPPORT);
        switch (cmd) {
        case SIOCGDRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 */
                bzero(drl, sizeof(*drl));
                TAILQ_FOREACH(dr, &V_nd_defrouter, dr_entry) {
                        if (i >= DRLSTSIZ)
                                break;
                        drl->defrouter[i].rtaddr = dr->rtaddr;
                        in6_clearscope(&drl->defrouter[i].rtaddr);

                        drl->defrouter[i].flags = dr->flags;
                        drl->defrouter[i].rtlifetime = dr->rtlifetime;
                        drl->defrouter[i].expire = dr->expire +
                            (time_second - time_uptime);
                        drl->defrouter[i].if_index = dr->ifp->if_index;
                        i++;
                }
                break;
        case SIOCGPRLST_IN6:
                /*
                 * obsolete API, use sysctl under net.inet6.icmp6
                 *
                 * XXX the structure in6_prlist was changed in backward-
                 * incompatible manner.  in6_oprlist is used for SIOCGPRLST_IN6,
                 * in6_prlist is used for nd6_sysctl() - fill_prlist().
                 */
                /*
                 * XXX meaning of fields, especialy "raflags", is very
                 * differnet between RA prefix list and RR/static prefix list.
                 * how about separating ioctls into two?
                 */
                bzero(oprl, sizeof(*oprl));
                LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                        struct nd_pfxrouter *pfr;
                        int j;

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

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

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

                        i++;
                }

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

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

                        ND_IFINFO(ifp)->basereachable = ND.basereachable;
                        if (ND.basereachable != obasereachable)
                                ND_IFINFO(ifp)->reachable =
                                    ND_COMPUTE_RTIME(ND.basereachable);
                }
                if (ND.retrans != 0)
                        ND_IFINFO(ifp)->retrans = ND.retrans;
                if (ND.chlim != 0)
                        ND_IFINFO(ifp)->chlim = ND.chlim;
                /* FALLTHROUGH */
        case SIOCSIFINFO_FLAGS:
        {
                struct ifaddr *ifa;
                struct in6_ifaddr *ia;

                if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) &&
                    !(ND.flags & ND6_IFF_IFDISABLED)) {
                        /* ifdisabled 1->0 transision */

                        /*
                         * If the interface is marked as ND6_IFF_IFDISABLED and
                         * has an link-local address with IN6_IFF_DUPLICATED,
                         * do not clear ND6_IFF_IFDISABLED.
                         * See RFC 4862, Section 5.4.5.
                         */
                        int duplicated_linklocal = 0;

                        IF_ADDR_RLOCK(ifp);
                        TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                                if (ifa->ifa_addr->sa_family != AF_INET6)
                                        continue;
                                ia = (struct in6_ifaddr *)ifa;
                                if ((ia->ia6_flags & IN6_IFF_DUPLICATED) &&
                                    IN6_IS_ADDR_LINKLOCAL(IA6_IN6(ia))) {
                                        duplicated_linklocal = 1;
                                        break;
                                }
                        }
                        IF_ADDR_RUNLOCK(ifp);

                        if (duplicated_linklocal) {
                                ND.flags |= ND6_IFF_IFDISABLED;
                                log(LOG_ERR, "Cannot enable an interface"
                                    " with a link-local address marked"
                                    " duplicate.\n");
                        } else {
                                ND_IFINFO(ifp)->flags &= ~ND6_IFF_IFDISABLED;
                                if (ifp->if_flags & IFF_UP)
                                        in6_if_up(ifp);
                        }
                } else if (!(ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) &&
                            (ND.flags & ND6_IFF_IFDISABLED)) {
                        /* ifdisabled 0->1 transision */
                        /* Mark all IPv6 address as tentative. */

                        ND_IFINFO(ifp)->flags |= ND6_IFF_IFDISABLED;
                        IF_ADDR_RLOCK(ifp);
                        TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                                if (ifa->ifa_addr->sa_family != AF_INET6)
                                        continue;
                                ia = (struct in6_ifaddr *)ifa;
                                ia->ia6_flags |= IN6_IFF_TENTATIVE;
                        }
                        IF_ADDR_RUNLOCK(ifp);
                }

                if (ND.flags & ND6_IFF_AUTO_LINKLOCAL) {
                        if (!(ND_IFINFO(ifp)->flags & ND6_IFF_AUTO_LINKLOCAL)) {
                                /* auto_linklocal 0->1 transision */

                                /* If no link-local address on ifp, configure */
                                ND_IFINFO(ifp)->flags |= ND6_IFF_AUTO_LINKLOCAL;
                                in6_ifattach(ifp, NULL);
                        } else if (!(ND.flags & ND6_IFF_IFDISABLED) &&
                            ifp->if_flags & IFF_UP) {
                                /*
                                 * When the IF already has
                                 * ND6_IFF_AUTO_LINKLOCAL, no link-local
                                 * address is assigned, and IFF_UP, try to
                                 * assign one.
                                 */
                                int haslinklocal = 0;
                        
                                IF_ADDR_RLOCK(ifp);
                                TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                                        if (ifa->ifa_addr->sa_family != AF_INET6)
                                                continue;
                                        ia = (struct in6_ifaddr *)ifa;
                                        if (IN6_IS_ADDR_LINKLOCAL(IA6_IN6(ia))) {
                                                haslinklocal = 1;
                                                break;
                                        }
                                }
                                IF_ADDR_RUNLOCK(ifp);
                                if (!haslinklocal)
                                        in6_ifattach(ifp, NULL);
                        }
                }
        }
                ND_IFINFO(ifp)->flags = ND.flags;
                break;
#undef ND
        case SIOCSNDFLUSH_IN6:  /* XXX: the ioctl name is confusing... */
                /* sync kernel routing table with the default router list */
                defrouter_reset();
                defrouter_select();
                break;
        case SIOCSPFXFLUSH_IN6:
        {
                /* flush all the prefix advertised by routers */
                struct nd_prefix *pr, *next;

                LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, next) {
                        struct in6_ifaddr *ia, *ia_next;

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

                        /* do we really have to remove addresses as well? */
                        /* XXXRW: in6_ifaddrhead locking. */
                        TAILQ_FOREACH_SAFE(ia, &V_in6_ifaddrhead, ia_link,
                            ia_next) {
                                if ((ia->ia6_flags & IN6_IFF_AUTOCONF) == 0)
                                        continue;

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

                defrouter_reset();
                TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, next) {
                        defrtrlist_del(dr);
                }
                defrouter_select();
                break;
        }
        case SIOCGNBRINFO_IN6:
        {
                struct llentry *ln;
                struct in6_addr nb_addr = nbi->addr; /* make local for safety */

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

                IF_AFDATA_RLOCK(ifp);
                ln = nd6_lookup(&nb_addr, 0, ifp);
                IF_AFDATA_RUNLOCK(ifp);

                if (ln == NULL) {
                        error = EINVAL;
                        break;
                }
                nbi->state = ln->ln_state;
                nbi->asked = ln->la_asked;
                nbi->isrouter = ln->ln_router;
                if (ln->la_expire == 0)
                        nbi->expire = 0;
                else
                        nbi->expire = ln->la_expire +
                            (time_second - time_uptime);
                LLE_RUNLOCK(ln);
                break;
        }
        case SIOCGDEFIFACE_IN6: /* XXX: should be implemented as a sysctl? */
                ndif->ifindex = V_nd6_defifindex;
                break;
        case SIOCSDEFIFACE_IN6: /* XXX: should be implemented as a sysctl? */
                return (nd6_setdefaultiface(ndif->ifindex));
        }
        return (error);
}

/*
 * Create neighbor cache entry and cache link-layer address,
 * on reception of inbound ND6 packets.  (RS/RA/NS/redirect)
 *
 * type - ICMP6 type
 * code - type dependent information
 *
 * XXXXX
 *  The caller of this function already acquired the ndp 
 *  cache table lock because the cache entry is returned.
 */
struct llentry *
nd6_cache_lladdr(struct ifnet *ifp, struct in6_addr *from, char *lladdr,
    int lladdrlen, int type, int code)
{
        struct llentry *ln = NULL;
        int is_newentry;
        int do_update;
        int olladdr;
        int llchange;
        int flags;
        int newstate = 0;
        uint16_t router = 0;
        struct sockaddr_in6 sin6;
        struct mbuf *chain = NULL;
        int static_route = 0;

        IF_AFDATA_UNLOCK_ASSERT(ifp);

        KASSERT(ifp != NULL, ("%s: ifp == NULL", __func__));
        KASSERT(from != NULL, ("%s: from == NULL", __func__));

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

        /*
         * Validation about ifp->if_addrlen and lladdrlen must be done in
         * the caller.
         *
         * XXX If the link does not have link-layer adderss, what should
         * we do? (ifp->if_addrlen == 0)
         * Spec says nothing in sections for RA, RS and NA.  There's small
         * description on it in NS section (RFC 2461 7.2.3).
         */
        flags = lladdr ? ND6_EXCLUSIVE : 0;
        IF_AFDATA_RLOCK(ifp);
        ln = nd6_lookup(from, flags, ifp);
        IF_AFDATA_RUNLOCK(ifp);
        if (ln == NULL) {
                flags |= ND6_EXCLUSIVE;
                IF_AFDATA_LOCK(ifp);
                ln = nd6_lookup(from, flags | ND6_CREATE, ifp);
                IF_AFDATA_UNLOCK(ifp);
                is_newentry = 1;
        } else {
                /* do nothing if static ndp is set */
                if (ln->la_flags & LLE_STATIC) {
                        static_route = 1;
                        goto done;
                }
                is_newentry = 0;
        }
        if (ln == NULL)
                return (NULL);

        olladdr = (ln->la_flags & LLE_VALID) ? 1 : 0;
        if (olladdr && lladdr) {
                llchange = bcmp(lladdr, &ln->ll_addr,
                    ifp->if_addrlen);
        } 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?
                 */
                bcopy(lladdr, &ln->ll_addr, ifp->if_addrlen);
                ln->la_flags |= LLE_VALID;
                EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
        }

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

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

                if (ln->ln_state == ND6_LLINFO_STALE) {
                        if (ln->la_hold != NULL)
                                nd6_grab_holdchain(ln, &chain, &sin6);
                } else if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
                        /* probe right away */
                        nd6_llinfo_settimer_locked((void *)ln, 0);
                }
        }

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

        if (ln != NULL) {
                static_route = (ln->la_flags & LLE_STATIC);
                router = ln->ln_router;

                if (flags & ND6_EXCLUSIVE)
                        LLE_WUNLOCK(ln);
                else
                        LLE_RUNLOCK(ln);
                if (static_route)
                        ln = NULL;
        }
        if (chain != NULL)
                nd6_flush_holdchain(ifp, ifp, chain, &sin6);
        
        /*
         * 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 && router &&
            ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
                /*
                 * guaranteed recursion
                 */
                defrouter_select();
        }
        
        return (ln);
done:   
        if (ln != NULL) {
                if (flags & ND6_EXCLUSIVE)
                        LLE_WUNLOCK(ln);
                else
                        LLE_RUNLOCK(ln);
                if (static_route)
                        ln = NULL;
        }
        return (ln);
}

static void
nd6_slowtimo(void *arg)
{
        CURVNET_SET((struct vnet *) arg);
        struct nd_ifinfo *nd6if;
        struct ifnet *ifp;

        callout_reset(&V_nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
            nd6_slowtimo, curvnet);
        IFNET_RLOCK_NOSLEEP();
        TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                if (ifp->if_afdata[AF_INET6] == NULL)
                        continue;
                nd6if = ND_IFINFO(ifp);
                if (nd6if->basereachable && /* already initialized */
                    (nd6if->recalctm -= ND6_SLOWTIMER_INTERVAL) <= 0) {
                        /*
                         * Since reachable time rarely changes by router
                         * advertisements, we SHOULD insure that a new random
                         * value gets recomputed at least once every few hours.
                         * (RFC 2461, 6.3.4)
                         */
                        nd6if->recalctm = V_nd6_recalc_reachtm_interval;
                        nd6if->reachable = ND_COMPUTE_RTIME(nd6if->basereachable);
                }
        }
        IFNET_RUNLOCK_NOSLEEP();
        CURVNET_RESTORE();
}

void
nd6_grab_holdchain(struct llentry *ln, struct mbuf **chain,
    struct sockaddr_in6 *sin6)
{

        LLE_WLOCK_ASSERT(ln);

        *chain = ln->la_hold;
        ln->la_hold = NULL;
        memcpy(sin6, L3_ADDR_SIN6(ln), sizeof(*sin6));

        if (ln->ln_state == ND6_LLINFO_STALE) {

                /*
                 * 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)
                 */
                ln->la_asked = 0;
                ln->ln_state = ND6_LLINFO_DELAY;
                nd6_llinfo_settimer_locked(ln, (long)V_nd6_delay * hz);
        }
}

static int
nd6_output_ifp(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
    struct sockaddr_in6 *dst)
{
        int error;
        int ip6len;
        struct ip6_hdr *ip6;
        struct m_tag *mtag;

#ifdef MAC
        mac_netinet6_nd6_send(ifp, m);
#endif

        /*
         * If called from nd6_ns_output() (NS), nd6_na_output() (NA),
         * icmp6_redirect_output() (REDIRECT) or from rip6_output() (RS, RA
         * as handled by rtsol and rtadvd), mbufs will be tagged for SeND
         * to be diverted to user space.  When re-injected into the kernel,
         * send_output() will directly dispatch them to the outgoing interface.
         */
        if (send_sendso_input_hook != NULL) {
                mtag = m_tag_find(m, PACKET_TAG_ND_OUTGOING, NULL);
                if (mtag != NULL) {
                        ip6 = mtod(m, struct ip6_hdr *);
                        ip6len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
                        /* Use the SEND socket */
                        error = send_sendso_input_hook(m, ifp, SND_OUT,
                            ip6len);
                        /* -1 == no app on SEND socket */
                        if (error == 0 || error != -1)
                            return (error);
                }
        }

        m_clrprotoflags(m);     /* Avoid confusing lower layers. */
        IP_PROBE(send, NULL, NULL, mtod(m, struct ip6_hdr *), ifp, NULL,
            mtod(m, struct ip6_hdr *));

        if ((ifp->if_flags & IFF_LOOPBACK) == 0)
                origifp = ifp;

        error = (*ifp->if_output)(origifp, m, (struct sockaddr *)dst, NULL);
        return (error);
}

/*
 * IPv6 packet output - light version.
 * Checks if destination LLE exists and is in proper state
 * (e.g no modification required). If not true, fall back to
 * "heavy" version.
 */
int
nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
    struct sockaddr_in6 *dst, struct rtentry *rt0)
{
        struct llentry *ln = NULL;

        /* discard the packet if IPv6 operation is disabled on the interface */
        if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)) {
                m_freem(m);
                return (ENETDOWN); /* better error? */
        }

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

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

        IF_AFDATA_RLOCK(ifp);
        ln = nd6_lookup(&dst->sin6_addr, 0, ifp);
        IF_AFDATA_RUNLOCK(ifp);

        /*
         * Perform fast path for the following cases:
         * 1) lle state is REACHABLE
         * 2) lle state is DELAY (NS message sentNS message sent)
         *
         * Every other case involves lle modification, so we handle
         * them separately.
         */
        if (ln == NULL || (ln->ln_state != ND6_LLINFO_REACHABLE &&
            ln->ln_state != ND6_LLINFO_DELAY)) {
                /* Fall back to slow processing path */
                if (ln != NULL)
                        LLE_RUNLOCK(ln);
                return (nd6_output_lle(ifp, origifp, m, dst));
        }

sendpkt:
        if (ln != NULL)
                LLE_RUNLOCK(ln);

        return (nd6_output_ifp(ifp, origifp, m, dst));
}


/*
 * Output IPv6 packet - heavy version.
 * Function assume that either
 * 1) destination LLE does not exist, is invalid or stale, so
 *   ND6_EXCLUSIVE lock needs to be acquired
 * 2) destination lle is provided (with ND6_EXCLUSIVE lock),
 *   in that case packets are queued in &chain.
 *
 */
static int
nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
    struct sockaddr_in6 *dst)
{
        struct llentry *lle = NULL;
        int flags = 0;

        KASSERT(m != NULL, ("NULL mbuf, nothing to send"));
        /* discard the packet if IPv6 operation is disabled on the interface */
        if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)) {
                m_freem(m);
                return (ENETDOWN); /* better error? */
        }

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

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

        /*
         * 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).
         */
        if (lle == NULL) {
                IF_AFDATA_RLOCK(ifp);
                lle = nd6_lookup(&dst->sin6_addr, ND6_EXCLUSIVE, ifp);
                IF_AFDATA_RUNLOCK(ifp);
                if ((lle == NULL) && nd6_is_addr_neighbor(dst, ifp))  {
                        /*
                         * 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.
                         */
                        flags = ND6_CREATE | ND6_EXCLUSIVE;
                        IF_AFDATA_LOCK(ifp);
                        lle = nd6_lookup(&dst->sin6_addr, flags, ifp);
                        IF_AFDATA_UNLOCK(ifp);
                }
        } 
        if (lle == NULL) {
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0 &&
                    !(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) {
                        char ip6buf[INET6_ADDRSTRLEN];
                        log(LOG_DEBUG,
                            "nd6_output: can't allocate llinfo for %s "
                            "(ln=%p)\n",
                            ip6_sprintf(ip6buf, &dst->sin6_addr), lle);
                        m_freem(m);
                        return (ENOBUFS);
                }
                goto sendpkt;   /* send anyway */
        }

        LLE_WLOCK_ASSERT(lle);

        /* We don't have to do link-layer address resolution on a p2p link. */
        if ((ifp->if_flags & IFF_POINTOPOINT) != 0 &&
            lle->ln_state < ND6_LLINFO_REACHABLE) {
                lle->ln_state = ND6_LLINFO_STALE;
                nd6_llinfo_settimer_locked(lle, (long)V_nd6_gctimer * hz);
        }

        /*
         * The first time we send a packet to a neighbor whose entry is
         * STALE, we have to change the state to DELAY and a sets a timer to
         * expire in DELAY_FIRST_PROBE_TIME seconds to ensure do
         * neighbor unreachability detection on expiration.
         * (RFC 2461 7.3.3)
         */
        if (lle->ln_state == ND6_LLINFO_STALE) {
                lle->la_asked = 0;
                lle->ln_state = ND6_LLINFO_DELAY;
                nd6_llinfo_settimer_locked(lle, (long)V_nd6_delay * hz);
        }

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

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

        if (lle->la_hold != NULL) {
                struct mbuf *m_hold;
                int i;
                
                i = 0;
                for (m_hold = lle->la_hold; m_hold; m_hold = m_hold->m_nextpkt){
                        i++;
                        if (m_hold->m_nextpkt == NULL) {
                                m_hold->m_nextpkt = m;
                                break;
                        }
                }
                while (i >= V_nd6_maxqueuelen) {
                        m_hold = lle->la_hold;
                        lle->la_hold = lle->la_hold->m_nextpkt;
                        m_freem(m_hold);
                        i--;
                }
        } else {
                lle->la_hold = m;
        }

        /*
         * If there has been no NS for the neighbor after entering the
         * INCOMPLETE state, send the first solicitation.
         */
        if (!ND6_LLINFO_PERMANENT(lle) && lle->la_asked == 0) {
                lle->la_asked++;
                
                nd6_llinfo_settimer_locked(lle,
                    (long)ND_IFINFO(ifp)->retrans * hz / 1000);
                LLE_WUNLOCK(lle);
                nd6_ns_output(ifp, NULL, &dst->sin6_addr, lle, NULL);
        } else {
                /* We did the lookup so we need to do the unlock here. */
                LLE_WUNLOCK(lle);
        }

        return (0);

  sendpkt:
        if (lle != NULL)
                LLE_WUNLOCK(lle);

        return (nd6_output_ifp(ifp, origifp, m, dst));
}


int
nd6_flush_holdchain(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *chain,
    struct sockaddr_in6 *dst)
{
        struct mbuf *m, *m_head;
        struct ifnet *outifp;
        int error = 0;

        m_head = chain;
        if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                outifp = origifp;
        else
                outifp = ifp;
        
        while (m_head) {
                m = m_head;
                m_head = m_head->m_nextpkt;
                error = nd6_output_ifp(ifp, origifp, m, dst);
        }

        /*
         * XXX
         * note that intermediate errors are blindly ignored - but this is 
         * the same convention as used with nd6_output when called by
         * nd6_cache_lladdr
         */
        return (error);
}       


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_IEEE80211:
        case IFT_INFINIBAND:
        case IFT_BRIDGE:
        case IFT_PROPVIRTUAL:
                return (1);
        default:
                return (0);
        }
}

/*
 * Add pernament ND6 link-layer record for given
 * interface address.
 *
 * Very similar to IPv4 arp_ifinit(), but:
 * 1) IPv6 DAD is performed in different place
 * 2) It is called by IPv6 protocol stack in contrast to
 * arp_ifinit() which is typically called in SIOCSIFADDR
 * driver ioctl handler.
 *
 */
int
nd6_add_ifa_lle(struct in6_ifaddr *ia)
{
        struct ifnet *ifp;
        struct llentry *ln;

        ifp = ia->ia_ifa.ifa_ifp;
        if (nd6_need_cache(ifp) == 0)
                return (0);
        IF_AFDATA_LOCK(ifp);
        ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
        ln = lla_lookup(LLTABLE6(ifp), (LLE_CREATE | LLE_IFADDR |
            LLE_EXCLUSIVE), (struct sockaddr *)&ia->ia_addr);
        IF_AFDATA_UNLOCK(ifp);
        if (ln != NULL) {
                ln->la_expire = 0;  /* for IPv6 this means permanent */
                ln->ln_state = ND6_LLINFO_REACHABLE;
                LLE_WUNLOCK(ln);
                return (0);
        }

        return (ENOBUFS);
}

/*
 * Removes ALL lle records for interface address prefix.
 * XXXME: That's probably not we really want to do, we need
 * to remove address record only and keep other records
 * until we determine if given prefix is really going 
 * to be removed.
 */
void
nd6_rem_ifa_lle(struct in6_ifaddr *ia)
{
        struct sockaddr_in6 mask, addr;
        struct ifnet *ifp;

        ifp = ia->ia_ifa.ifa_ifp;
        memcpy(&addr, &ia->ia_addr, sizeof(ia->ia_addr));
        memcpy(&mask, &ia->ia_prefixmask, sizeof(ia->ia_prefixmask));
        lltable_prefix_free(AF_INET6, (struct sockaddr *)&addr,
                    (struct sockaddr *)&mask, LLE_STATIC);
}

/*
 * the callers of this function need to be re-worked to drop
 * the lle lock, drop here for now
 */
int
nd6_storelladdr(struct ifnet *ifp, struct mbuf *m,
    const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
{
        struct llentry *ln;

        if (pflags != NULL)
                *pflags = 0;
        IF_AFDATA_UNLOCK_ASSERT(ifp);
        if (m != NULL && m->m_flags & M_MCAST) {
                switch (ifp->if_type) {
                case IFT_ETHER:
                case IFT_FDDI:
                case IFT_L2VLAN:
                case IFT_IEEE80211:
                case IFT_BRIDGE:
                case IFT_ISO88025:
                        ETHER_MAP_IPV6_MULTICAST(&SIN6(dst)->sin6_addr,
                                                 desten);
                        return (0);
                default:
                        m_freem(m);
                        return (EAFNOSUPPORT);
                }
        }


        /*
         * the entry should have been created in nd6_store_lladdr
         */
        IF_AFDATA_RLOCK(ifp);
        ln = lla_lookup(LLTABLE6(ifp), 0, dst);
        IF_AFDATA_RUNLOCK(ifp);
        if ((ln == NULL) || !(ln->la_flags & LLE_VALID)) {
                if (ln != NULL)
                        LLE_RUNLOCK(ln);
                /* this could happen, if we could not allocate memory */
                m_freem(m);
                return (1);
        }

        bcopy(&ln->ll_addr, desten, ifp->if_addrlen);
        if (pflags != NULL)
                *pflags = ln->la_flags;
        LLE_RUNLOCK(ln);
        /*
         * A *small* use after free race exists here
         */
        return (0);
}

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

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

        ln->la_hold = NULL;
        return;
}

static int nd6_sysctl_drlist(SYSCTL_HANDLER_ARGS);
static int nd6_sysctl_prlist(SYSCTL_HANDLER_ARGS);
#ifdef SYSCTL_DECL
SYSCTL_DECL(_net_inet6_icmp6);
#endif
SYSCTL_NODE(_net_inet6_icmp6, ICMPV6CTL_ND6_DRLIST, nd6_drlist,
        CTLFLAG_RD, nd6_sysctl_drlist, "");
SYSCTL_NODE(_net_inet6_icmp6, ICMPV6CTL_ND6_PRLIST, nd6_prlist,
        CTLFLAG_RD, nd6_sysctl_prlist, "");
SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_MAXQLEN, nd6_maxqueuelen,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_maxqueuelen), 1, "");
SYSCTL_INT(_net_inet6_icmp6, OID_AUTO, nd6_gctimer,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_gctimer), (60 * 60 * 24), "");

static int
nd6_sysctl_drlist(SYSCTL_HANDLER_ARGS)
{
        struct in6_defrouter d;
        struct nd_defrouter *dr;
        int error;

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

        bzero(&d, sizeof(d));
        d.rtaddr.sin6_family = AF_INET6;
        d.rtaddr.sin6_len = sizeof(d.rtaddr);

        /*
         * XXX locking
         */
        TAILQ_FOREACH(dr, &V_nd_defrouter, dr_entry) {
                d.rtaddr.sin6_addr = dr->rtaddr;
                error = sa6_recoverscope(&d.rtaddr);
                if (error != 0)
                        return (error);
                d.flags = dr->flags;
                d.rtlifetime = dr->rtlifetime;
                d.expire = dr->expire + (time_second - time_uptime);
                d.if_index = dr->ifp->if_index;
                error = SYSCTL_OUT(req, &d, sizeof(d));
                if (error != 0)
                        return (error);
        }
        return (0);
}

static int
nd6_sysctl_prlist(SYSCTL_HANDLER_ARGS)
{
        struct in6_prefix p;
        struct sockaddr_in6 s6;
        struct nd_prefix *pr;
        struct nd_pfxrouter *pfr;
        time_t maxexpire;
        int error;
        char ip6buf[INET6_ADDRSTRLEN];

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

        bzero(&p, sizeof(p));
        p.origin = PR_ORIG_RA;
        bzero(&s6, sizeof(s6));
        s6.sin6_family = AF_INET6;
        s6.sin6_len = sizeof(s6);

        /*
         * XXX locking
         */
        LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                p.prefix = pr->ndpr_prefix;
                if (sa6_recoverscope(&p.prefix)) {
                        log(LOG_ERR, "scope error in prefix list (%s)\n",
                            ip6_sprintf(ip6buf, &p.prefix.sin6_addr));
                        /* XXX: press on... */
                }
                p.raflags = pr->ndpr_raf;
                p.prefixlen = pr->ndpr_plen;
                p.vltime = pr->ndpr_vltime;
                p.pltime = pr->ndpr_pltime;
                p.if_index = pr->ndpr_ifp->if_index;
                if (pr->ndpr_vltime == ND6_INFINITE_LIFETIME)
                        p.expire = 0;
                else {
                        /* XXX: we assume time_t is signed. */
                        maxexpire = (-1) &
                            ~((time_t)1 << ((sizeof(maxexpire) * 8) - 1));
                        if (pr->ndpr_vltime < maxexpire - pr->ndpr_lastupdate)
                                p.expire = pr->ndpr_lastupdate +
                                    pr->ndpr_vltime +
                                    (time_second - time_uptime);
                        else
                                p.expire = maxexpire;
                }
                p.refcnt = pr->ndpr_refcnt;
                p.flags = pr->ndpr_stateflags;
                p.advrtrs = 0;
                LIST_FOREACH(pfr, &pr->ndpr_advrtrs, pfr_entry)
                        p.advrtrs++;
                error = SYSCTL_OUT(req, &p, sizeof(p));
                if (error != 0)
                        return (error);
                LIST_FOREACH(pfr, &pr->ndpr_advrtrs, pfr_entry) {
                        s6.sin6_addr = pfr->router->rtaddr;
                        if (sa6_recoverscope(&s6))
                                log(LOG_ERR,
                                    "scope error in prefix list (%s)\n",
                                    ip6_sprintf(ip6buf, &pfr->router->rtaddr));
                        error = SYSCTL_OUT(req, &s6, sizeof(s6));
                        if (error != 0)
                                return (error);
                }
        }
        return (0);
}