FreeBSD/Linux Kernel Cross Reference
sys/netinet6/nd6.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * 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: releng/12.0/sys/netinet6/nd6.c 336676 2018-07-24 16:35:52Z andrew $");
    
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/callout.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/mutex.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/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_dl.h>
    #include <net/if_types.h>
    #include <net/route.h>
    #include <net/vnet.h>
    
    #include <netinet/in.h>
    #include <netinet/in_kdtrace.h>
    #include <net/if_llatbl.h>
    #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))
    
    MALLOC_DEFINE(M_IP6NDP, "ip6ndp", "IPv6 Neighbor Discovery");
    
    /* 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 */
   VNET_DEFINE_STATIC(int, nd6_maxndopt) = 10; /* max # of ND options allowed */
   
   VNET_DEFINE(int, nd6_maxnudhint) = 0;   /* max # of subsequent upper
                                            * layer hints */
   VNET_DEFINE_STATIC(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, iflladdr_event_eh;
   
   VNET_DEFINE(struct nd_drhead, nd_defrouter);
   VNET_DEFINE(struct nd_prhead, nd_prefix);
   VNET_DEFINE(struct rwlock, nd6_lock);
   VNET_DEFINE(uint64_t, nd6_list_genid);
   VNET_DEFINE(struct mtx, nd6_onlink_mtx);
   
   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(const 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 void nd6_free(struct llentry **, int);
   static void nd6_free_redirect(const struct llentry *);
   static void nd6_llinfo_timer(void *);
   static void nd6_llinfo_settimer_locked(struct llentry *, long);
   static void clear_llinfo_pqueue(struct llentry *);
   static void nd6_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
   static int nd6_resolve_slow(struct ifnet *, int, struct mbuf *,
       const struct sockaddr_in6 *, u_char *, uint32_t *, struct llentry **);
   static int nd6_need_cache(struct ifnet *);
    
   
   VNET_DEFINE_STATIC(struct callout, nd6_slowtimo_ch);
   #define V_nd6_slowtimo_ch               VNET(nd6_slowtimo_ch)
   
   VNET_DEFINE(struct callout, nd6_timer_ch);
   #define V_nd6_timer_ch                  VNET(nd6_timer_ch)
   
   static void
   nd6_lle_event(void *arg __unused, struct llentry *lle, int evt)
   {
           struct rt_addrinfo rtinfo;
           struct sockaddr_in6 dst;
           struct sockaddr_dl gw;
           struct ifnet *ifp;
           int type;
           int fibnum;
   
           LLE_WLOCK_ASSERT(lle);
   
           if (lltable_get_af(lle->lle_tbl) != AF_INET6)
                   return;
   
           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;
           }
   
           ifp = lltable_get_ifp(lle->lle_tbl);
   
           bzero(&dst, sizeof(dst));
           bzero(&gw, sizeof(gw));
           bzero(&rtinfo, sizeof(rtinfo));
           lltable_fill_sa_entry(lle, (struct sockaddr *)&dst);
           dst.sin6_scope_id = in6_getscopezone(ifp,
               in6_addrscope(&dst.sin6_addr));
           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;
           fibnum = V_rt_add_addr_allfibs ? RT_ALL_FIBS : ifp->if_fib;
           rt_missmsg_fib(type, &rtinfo, RTF_HOST | RTF_LLDATA | (
               type == RTM_ADD ? RTF_UP: 0), 0, fibnum);
   }
   
   /*
    * A handler for interface link layer address change event.
    */
   static void
   nd6_iflladdr(void *arg __unused, struct ifnet *ifp)
   {
   
           lltable_update_ifaddr(LLTABLE6(ifp));
   }
   
   void
   nd6_init(void)
   {
   
           mtx_init(&V_nd6_onlink_mtx, "nd6 onlink", NULL, MTX_DEF);
           rw_init(&V_nd6_lock, "nd6 list");
   
           LIST_INIT(&V_nd_prefix);
           TAILQ_INIT(&V_nd_defrouter);
   
           /* Start timers. */
           callout_init(&V_nd6_slowtimo_ch, 0);
           callout_reset(&V_nd6_slowtimo_ch, ND6_SLOWTIMER_INTERVAL * hz,
               nd6_slowtimo, curvnet);
   
           callout_init(&V_nd6_timer_ch, 0);
           callout_reset(&V_nd6_timer_ch, hz, nd6_timer, curvnet);
   
           nd6_dad_init();
           if (IS_DEFAULT_VNET(curvnet)) {
                   lle_event_eh = EVENTHANDLER_REGISTER(lle_event, nd6_lle_event,
                       NULL, EVENTHANDLER_PRI_ANY);
                   iflladdr_event_eh = EVENTHANDLER_REGISTER(iflladdr_event,
                       nd6_iflladdr, 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);
                   EVENTHANDLER_DEREGISTER(iflladdr_event, iflladdr_event_eh);
           }
           rw_destroy(&V_nd6_lock);
           mtx_destroy(&V_nd6_onlink_mtx);
   }
   #endif
   
   struct nd_ifinfo *
   nd6_ifattach(struct ifnet *ifp)
   {
           struct nd_ifinfo *nd;
   
           nd = 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 ifnet *ifp, struct nd_ifinfo *nd)
   {
           struct ifaddr *ifa, *next;
   
           IF_ADDR_RLOCK(ifp);
           CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, next) {
                   if (ifa->ifa_addr->sa_family != AF_INET6)
                           continue;
   
                   /* stop DAD processing */
                   nd6_dad_stop(ifa);
           }
           IF_ADDR_RUNLOCK(ifp);
   
           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)
   {
           if (ifp->if_afdata[AF_INET6] == NULL)
                   return;
   
           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;
           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 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 accommodate future extension to the protocol.
                            */
                           nd6log((LOG_DEBUG,
                               "nd6_options: unsupported option %d - "
                               "option ignored\n", nd_opt->nd_opt_type));
                   }
   
   skip1:
                   i++;
                   if (i > 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
    */
   static 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->lle_timer);
           } 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->lle_timer, INT_MAX,
                               nd6_llinfo_timer, ln);
                   } else {
                           ln->ln_ntick = 0;
                           canceled = callout_reset(&ln->lle_timer, tick,
                               nd6_llinfo_timer, ln);
                   }
           }
           if (canceled > 0)
                   LLE_REMREF(ln);
   }
   
   /*
    * Gets source address of the first packet in hold queue
    * and stores it in @src.
    * Returns pointer to @src (if hold queue is not empty) or NULL.
    *
    * Set noinline to be dtrace-friendly
    */
   static __noinline struct in6_addr *
   nd6_llinfo_get_holdsrc(struct llentry *ln, struct in6_addr *src)
   {
           struct ip6_hdr hdr;
           struct mbuf *m;
   
           if (ln->la_hold == NULL)
                   return (NULL);
   
           /*
            * assume every packet in la_hold has the same IP header
            */
           m = ln->la_hold;
           if (sizeof(hdr) > m->m_len)
                   return (NULL);
   
           m_copydata(m, 0, sizeof(hdr), (caddr_t)&hdr);
           *src = hdr.ip6_src;
   
           return (src);
   }
   
   /*
    * Checks if we need to switch from STALE state.
    *
    * RFC 4861 requires switching from STALE to DELAY state
    * on first packet matching entry, waiting V_nd6_delay and
    * transition to PROBE state (if upper layer confirmation was
    * not received).
    *
    * This code performs a bit differently:
    * On packet hit we don't change state (but desired state
    * can be guessed by control plane). However, after V_nd6_delay
    * seconds code will transition to PROBE state (so DELAY state
    * is kinda skipped in most situations).
    *
    * Typically, V_nd6_gctimer is bigger than V_nd6_delay, so
    * we perform the following upon entering STALE state:
    *
    * 1) Arm timer to run each V_nd6_delay seconds to make sure that
    * if packet was transmitted at the start of given interval, we
    * would be able to switch to PROBE state in V_nd6_delay seconds
    * as user expects.
    *
    * 2) Reschedule timer until original V_nd6_gctimer expires keeping
    * lle in STALE state (remaining timer value stored in lle_remtime).
    *
    * 3) Reschedule timer if packet was transmitted less that V_nd6_delay
    * seconds ago.
    *
    * Returns non-zero value if the entry is still STALE (storing
    * the next timer interval in @pdelay).
    *
    * Returns zero value if original timer expired or we need to switch to
    * PROBE (store that in @do_switch variable).
    */
   static int
   nd6_is_stale(struct llentry *lle, long *pdelay, int *do_switch)
   {
           int nd_delay, nd_gctimer, r_skip_req;
           time_t lle_hittime;
           long delay;
   
           *do_switch = 0;
           nd_gctimer = V_nd6_gctimer;
           nd_delay = V_nd6_delay;
   
           LLE_REQ_LOCK(lle);
           r_skip_req = lle->r_skip_req;
           lle_hittime = lle->lle_hittime;
           LLE_REQ_UNLOCK(lle);
   
           if (r_skip_req > 0) {
   
                   /*
                    * Nonzero r_skip_req value was set upon entering
                    * STALE state. Since value was not changed, no
                    * packets were passed using this lle. Ask for
                    * timer reschedule and keep STALE state.
                    */
                   delay = (long)(MIN(nd_gctimer, nd_delay));
                   delay *= hz;
                   if (lle->lle_remtime > delay)
                           lle->lle_remtime -= delay;
                   else {
                           delay = lle->lle_remtime;
                           lle->lle_remtime = 0;
                   }
   
                   if (delay == 0) {
   
                           /*
                            * The original ng6_gctime timeout ended,
                            * no more rescheduling.
                            */
                           return (0);
                   }
   
                   *pdelay = delay;
                   return (1);
           }
   
           /*
            * Packet received. Verify timestamp
            */
           delay = (long)(time_uptime - lle_hittime);
           if (delay < nd_delay) {
   
                   /*
                    * V_nd6_delay still not passed since the first
                    * hit in STALE state.
                    * Reshedule timer and return.
                    */
                   *pdelay = (long)(nd_delay - delay) * hz;
                   return (1);
           }
   
           /* Request switching to probe */
           *do_switch = 1;
           return (0);
   }
   
   
   /*
    * Switch @lle state to new state optionally arming timers.
    *
    * Set noinline to be dtrace-friendly
    */
   __noinline void
   nd6_llinfo_setstate(struct llentry *lle, int newstate)
   {
           struct ifnet *ifp;
           int nd_gctimer, nd_delay;
           long delay, remtime;
   
           delay = 0;
           remtime = 0;
   
           switch (newstate) {
           case ND6_LLINFO_INCOMPLETE:
                   ifp = lle->lle_tbl->llt_ifp;
                   delay = (long)ND_IFINFO(ifp)->retrans * hz / 1000;
                   break;
           case ND6_LLINFO_REACHABLE:
                   if (!ND6_LLINFO_PERMANENT(lle)) {
                           ifp = lle->lle_tbl->llt_ifp;
                           delay = (long)ND_IFINFO(ifp)->reachable * hz;
                   }
                   break;
           case ND6_LLINFO_STALE:
   
                   /*
                    * Notify fast path that we want to know if any packet
                    * is transmitted by setting r_skip_req.
                    */
                   LLE_REQ_LOCK(lle);
                   lle->r_skip_req = 1;
                   LLE_REQ_UNLOCK(lle);
                   nd_delay = V_nd6_delay;
                   nd_gctimer = V_nd6_gctimer;
   
                   delay = (long)(MIN(nd_gctimer, nd_delay)) * hz;
                   remtime = (long)nd_gctimer * hz - delay;
                   break;
           case ND6_LLINFO_DELAY:
                   lle->la_asked = 0;
                   delay = (long)V_nd6_delay * hz;
                   break;
           }
   
           if (delay > 0)
                   nd6_llinfo_settimer_locked(lle, delay);
   
           lle->lle_remtime = remtime;
           lle->ln_state = newstate;
   }
   
   /*
    * Timer-dependent part of nd state machine.
    *
    * Set noinline to be dtrace-friendly
    */
   static __noinline void
   nd6_llinfo_timer(void *arg)
   {
           struct llentry *ln;
           struct in6_addr *dst, *pdst, *psrc, src;
           struct ifnet *ifp;
           struct nd_ifinfo *ndi;
           int do_switch, send_ns;
           long delay;
   
           KASSERT(arg != NULL, ("%s: arg NULL", __func__));
           ln = (struct llentry *)arg;
           ifp = lltable_get_ifp(ln->lle_tbl);
           CURVNET_SET(ifp->if_vnet);
   
           ND6_RLOCK();
           LLE_WLOCK(ln);
           if (callout_pending(&ln->lle_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);
                   ND6_RUNLOCK();
                   CURVNET_RESTORE();
                   return;
           }
           ndi = ND_IFINFO(ifp);
           send_ns = 0;
           dst = &ln->r_l3addr.addr6;
           pdst = dst;
   
           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;
           }
   
           if (ln->la_flags & LLE_STATIC) {
                   goto done;
           }
   
           if (ln->la_flags & LLE_DELETED) {
                   nd6_free(&ln, 0);
                   goto done;
           }
   
           switch (ln->ln_state) {
           case ND6_LLINFO_INCOMPLETE:
                   if (ln->la_asked < V_nd6_mmaxtries) {
                           ln->la_asked++;
                           send_ns = 1;
                           /* Send NS to multicast address */
                           pdst = NULL;
                   } 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);
                           }
                           nd6_free(&ln, 0);
                           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))
                           nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
                   break;
   
           case ND6_LLINFO_STALE:
                   if (nd6_is_stale(ln, &delay, &do_switch) != 0) {
   
                           /*
                            * No packet has used this entry and GC timeout
                            * has not been passed. Reshedule timer and
                            * return.
                            */
                           nd6_llinfo_settimer_locked(ln, delay);
                           break;
                   }
   
                   if (do_switch == 0) {
   
                           /*
                            * GC timer has ended and entry hasn't been used.
                            * Run Garbage collector (RFC 4861, 5.3)
                            */
                           if (!ND6_LLINFO_PERMANENT(ln))
                                   nd6_free(&ln, 1);
                           break;
                   }
   
                   /* Entry has been used AND delay timer has ended. */
   
                   /* FALLTHROUGH */
   
           case ND6_LLINFO_DELAY:
                   if (ndi && (ndi->flags & ND6_IFF_PERFORMNUD) != 0) {
                           /* We need NUD */
                           ln->la_asked = 1;
                           nd6_llinfo_setstate(ln, ND6_LLINFO_PROBE);
                           send_ns = 1;
                   } else
                           nd6_llinfo_setstate(ln, ND6_LLINFO_STALE); /* XXX */
                   break;
           case ND6_LLINFO_PROBE:
                   if (ln->la_asked < V_nd6_umaxtries) {
                           ln->la_asked++;
                           send_ns = 1;
                   } else {
                           nd6_free(&ln, 0);
                   }
                   break;
           default:
                   panic("%s: paths in a dark night can be confusing: %d",
                       __func__, ln->ln_state);
           }
   done:
           if (ln != NULL)
                   ND6_RUNLOCK();
           if (send_ns != 0) {
                   nd6_llinfo_settimer_locked(ln, (long)ndi->retrans * hz / 1000);
                   psrc = nd6_llinfo_get_holdsrc(ln, &src);
                   LLE_FREE_LOCKED(ln);
                   ln = NULL;
                   nd6_ns_output(ifp, psrc, pdst, dst, NULL);
           }
   
           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_drhead drq;
           struct nd_prhead prl;
           struct nd_defrouter *dr, *ndr;
           struct nd_prefix *pr, *npr;
           struct in6_ifaddr *ia6, *nia6;
           uint64_t genid;
   
           TAILQ_INIT(&drq);
           LIST_INIT(&prl);
   
           ND6_WLOCK();
           TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, ndr)
                   if (dr->expire && dr->expire < time_uptime)
                           defrouter_unlink(dr, &drq);
           ND6_WUNLOCK();
   
           while ((dr = TAILQ_FIRST(&drq)) != NULL) {
                   TAILQ_REMOVE(&drq, dr, dr_entry);
                   defrouter_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:
           CK_STAILQ_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 if ((ia6->ia6_flags & IN6_IFF_TENTATIVE) != 0) {
                           /*
                            * Schedule DAD for a tentative address.  This happens
                            * if the interface was down or not running
                            * when the address was configured.
                            */
                           int delay;
   
                           delay = arc4random() %
                               (MAX_RTR_SOLICITATION_DELAY * hz);
                           nd6_dad_start((struct ifaddr *)ia6, delay);
                   } else {
                           /*
                            * Check status of the interface.  If it is down,
                            * mark the address as tentative for future DAD.
                            */
                           if ((ia6->ia_ifp->if_flags & IFF_UP) == 0 ||
                               (ia6->ia_ifp->if_drv_flags & IFF_DRV_RUNNING)
                                   == 0 ||
                               (ND_IFINFO(ia6->ia_ifp)->flags &
                                   ND6_IFF_IFDISABLED) != 0) {
                                  ia6->ia6_flags &= ~IN6_IFF_DUPLICATED;
                                  ia6->ia6_flags |= IN6_IFF_TENTATIVE;
                          }
                          /*
                           * A new RA might have made a deprecated address
                           * preferred.
                           */
                          ia6->ia6_flags &= ~IN6_IFF_DEPRECATED;
                  }
          }
  
          ND6_WLOCK();
  restart:
          LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, npr) {
                  /*
                   * Expire prefixes. Since the pltime is only used for
                   * autoconfigured addresses, pltime processing for prefixes is
                   * not necessary.
                   *
                   * Only unlink after all derived addresses have expired. This
                   * may not occur until two hours after the prefix has expired
                   * per RFC 4862. If the prefix expires before its derived
                   * addresses, mark it off-link. This will be done automatically
                   * after unlinking if no address references remain.
                   */
                  if (pr->ndpr_vltime == ND6_INFINITE_LIFETIME ||
                      time_uptime - pr->ndpr_lastupdate <= pr->ndpr_vltime)
                          continue;
  
                  if (pr->ndpr_addrcnt == 0) {
                          nd6_prefix_unlink(pr, &prl);
                          continue;
                  }
                  if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
                          genid = V_nd6_list_genid;
                          nd6_prefix_ref(pr);
                          ND6_WUNLOCK();
                          ND6_ONLINK_LOCK();
                          (void)nd6_prefix_offlink(pr);
                          ND6_ONLINK_UNLOCK();
                          ND6_WLOCK();
                          nd6_prefix_rele(pr);
                          if (genid != V_nd6_list_genid)
                                  goto restart;
                  }
          }
          ND6_WUNLOCK();
  
          while ((pr = LIST_FIRST(&prl)) != NULL) {
                  LIST_REMOVE(pr, ndpr_entry);
                  nd6_prefix_del(pr);
          }
  
          callout_reset(&V_nd6_timer_ch, V_nd6_prune * hz,
              nd6_timer, curvnet);
  
          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);
          CK_STAILQ_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);
  }
  
  /*
   * Remove prefix and default router list entries corresponding to ifp. Neighbor
   * cache entries are freed in in6_domifdetach().
   */
  void
  nd6_purge(struct ifnet *ifp)
  {
          struct nd_drhead drq;
          struct nd_prhead prl;
          struct nd_defrouter *dr, *ndr;
          struct nd_prefix *pr, *npr;
  
          TAILQ_INIT(&drq);
          LIST_INIT(&prl);
  
          /*
           * 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.
           */
          ND6_WLOCK();
          TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, ndr) {
                  if (dr->installed)
                          continue;
                  if (dr->ifp == ifp)
                          defrouter_unlink(dr, &drq);
          }
          TAILQ_FOREACH_SAFE(dr, &V_nd_defrouter, dr_entry, ndr) {
                  if (!dr->installed)
                          continue;
                  if (dr->ifp == ifp)
                          defrouter_unlink(dr, &drq);
          }
  
          /*
           * Remove prefixes on ifp. We should have already removed addresses on
           * this interface, so no addresses should be referencing these prefixes.
           */
          LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, npr) {
                  if (pr->ndpr_ifp == ifp)
                          nd6_prefix_unlink(pr, &prl);
          }
          ND6_WUNLOCK();
  
          /* Delete the unlinked router and prefix objects. */
          while ((dr = TAILQ_FIRST(&drq)) != NULL) {
                  TAILQ_REMOVE(&drq, dr, dr_entry);
                  defrouter_del(dr);
          }
          while ((pr = LIST_FIRST(&prl)) != NULL) {
                  LIST_REMOVE(pr, ndpr_entry);
                  nd6_prefix_del(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_fib(ifp->if_fib);
          }
  }
  
  /* 
   * the caller acquires and releases the lock on the lltbls
   * Returns the llentry locked
   */
  struct llentry *
  nd6_lookup(const struct in6_addr *addr6, int flags, struct ifnet *ifp)
  {
          struct sockaddr_in6 sin6;
          struct llentry *ln;
          
          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);
  
          ln = lla_lookup(LLTABLE6(ifp), flags, (struct sockaddr *)&sin6);
  
          return (ln);
  }
  
  struct llentry *
  nd6_alloc(const struct in6_addr *addr6, int flags, struct ifnet *ifp)
  {
          struct sockaddr_in6 sin6;
          struct llentry *ln;
  
          bzero(&sin6, sizeof(sin6));
          sin6.sin6_len = sizeof(struct sockaddr_in6);
          sin6.sin6_family = AF_INET6;
          sin6.sin6_addr = *addr6;
  
          ln = lltable_alloc_entry(LLTABLE6(ifp), 0, (struct sockaddr *)&sin6);
          if (ln != NULL)
                  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(const struct sockaddr_in6 *addr, struct ifnet *ifp)
  {
          struct nd_prefix *pr;
          struct ifaddr *ifa;
          struct rt_addrinfo info;
          struct sockaddr_in6 rt_key;
          const struct sockaddr *dst6;
          uint64_t genid;
          int error, fibnum;
  
          /*
           * 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);
          }
  
          bzero(&rt_key, sizeof(rt_key));
          bzero(&info, sizeof(info));
          info.rti_info[RTAX_DST] = (struct sockaddr *)&rt_key;
  
          /*
           * 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.
           */
          ND6_RLOCK();
  restart:
          LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                  if (pr->ndpr_ifp != ifp)
                          continue;
  
                  if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
                          dst6 = (const struct sockaddr *)&pr->ndpr_prefix;
  
                          /*
                           * We only need to check all FIBs if add_addr_allfibs
                           * is unset. If set, checking any FIB will suffice.
                           */
                          fibnum = V_rt_add_addr_allfibs ? rt_numfibs - 1 : 0;
                          for (; fibnum < rt_numfibs; fibnum++) {
                                  genid = V_nd6_list_genid;
                                  ND6_RUNLOCK();
  
                                  /*
                                   * Restore length field before
                                   * retrying lookup
                                   */
                                  rt_key.sin6_len = sizeof(rt_key);
                                  error = rib_lookup_info(fibnum, dst6, 0, 0,
                                                          &info);
  
                                  ND6_RLOCK();
                                  if (genid != V_nd6_list_genid)
                                          goto restart;
                                  if (error == 0)
                                          break;
                          }
                          if (error != 0)
                                  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,
                              &rt_key.sin6_addr))
                                  continue;
                  }
  
                  if (IN6_ARE_MASKED_ADDR_EQUAL(&pr->ndpr_prefix.sin6_addr,
                      &addr->sin6_addr, &pr->ndpr_mask)) {
                          ND6_RUNLOCK();
                          return (1);
                  }
          }
          ND6_RUNLOCK();
  
          /*
           * If the address is assigned on the node of the other side of
           * a p2p interface, the address should be a neighbor.
           */
          if (ifp->if_flags & IFF_POINTOPOINT) {
                  IF_ADDR_RLOCK(ifp);
                  CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != addr->sin6_family)
                                  continue;
                          if (ifa->ifa_dstaddr != NULL &&
                              sa_equal(addr, ifa->ifa_dstaddr)) {
                                  IF_ADDR_RUNLOCK(ifp);
                                  return 1;
                          }
                  }
                  IF_ADDR_RUNLOCK(ifp);
          }
  
          /*
           * 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(const 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.
   *
   * Set noinline to be dtrace-friendly
   */
  static __noinline void
  nd6_free(struct llentry **lnp, int gc)
  {
          struct ifnet *ifp;
          struct llentry *ln;
          struct nd_defrouter *dr;
  
          ln = *lnp;
          *lnp = NULL;
  
          LLE_WLOCK_ASSERT(ln);
          ND6_RLOCK_ASSERT();
  
          ifp = lltable_get_ifp(ln->lle_tbl);
          if ((ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) != 0)
                  dr = defrouter_lookup_locked(&ln->r_l3addr.addr6, ifp);
          else
                  dr = NULL;
          ND6_RUNLOCK();
  
          if ((ln->la_flags & LLE_DELETED) == 0)
                  EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_EXPIRED);
  
          /*
           * 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);
  
          if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
                  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);
  
                          LLE_REMREF(ln);
                          LLE_WUNLOCK(ln);
                          defrouter_rele(dr);
                          return;
                  }
  
                  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_fib() 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(&ln->r_l3addr.addr6, ifp);
                  }
  
                  if (dr) {
                          /*
                           * Since defrouter_select_fib() 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_fib(dr->ifp->if_fib);
                  }
  
                  /*
                   * If this entry was added by an on-link redirect, remove the
                   * corresponding host route.
                   */
                  if (ln->la_flags & LLE_REDIRECT)
                          nd6_free_redirect(ln);
  
                  if (ln->ln_router || dr)
                          LLE_WLOCK(ln);
          }
  
          /*
           * 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) {
                  /* Remove callout reference */
                  LLE_REMREF(ln);
                  lltable_unlink_entry(ln->lle_tbl, ln);
          }
          IF_AFDATA_UNLOCK(ifp);
  
          llentry_free(ln);
          if (dr != NULL)
                  defrouter_rele(dr);
  }
  
  static int
  nd6_isdynrte(const struct rtentry *rt, void *xap)
  {
  
          if (rt->rt_flags == (RTF_UP | RTF_HOST | RTF_DYNAMIC))
                  return (1);
  
          return (0);
  }
  /*
   * Remove the rtentry for the given llentry,
   * both of which were installed by a redirect.
   */
  static void
  nd6_free_redirect(const struct llentry *ln)
  {
          int fibnum;
          struct sockaddr_in6 sin6;
          struct rt_addrinfo info;
  
          lltable_fill_sa_entry(ln, (struct sockaddr *)&sin6);
          memset(&info, 0, sizeof(info));
          info.rti_info[RTAX_DST] = (struct sockaddr *)&sin6;
          info.rti_filter = nd6_isdynrte;
  
          for (fibnum = 0; fibnum < rt_numfibs; fibnum++)
                  rtrequest1_fib(RTM_DELETE, &info, NULL, fibnum);
  }
  
  /*
   * 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;
                                  defrouter_rele(dr);
                          }
                  }
                  break;
          }
  }
  
  
  int
  nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
  {
          struct in6_ndireq *ndi = (struct in6_ndireq *)data;
          struct in6_nbrinfo *nbi = (struct in6_nbrinfo *)data;
          struct in6_ndifreq *ndif = (struct in6_ndifreq *)data;
          int error = 0;
  
          if (ifp->if_afdata[AF_INET6] == NULL)
                  return (EPFNOSUPPORT);
          switch (cmd) {
          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.
                   * intended 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.
                           */
                          IF_ADDR_RLOCK(ifp);
                          CK_STAILQ_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)))
                                          break;
                          }
                          IF_ADDR_RUNLOCK(ifp);
  
                          if (ifa != NULL) {
                                  /* LLA is duplicated. */
                                  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 (V_ip6_dad_count > 0 &&
                              (ND_IFINFO(ifp)->flags & ND6_IFF_NO_DAD) == 0) {
                                  IF_ADDR_RLOCK(ifp);
                                  CK_STAILQ_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.
                                   */
                                  IF_ADDR_RLOCK(ifp);
                                  CK_STAILQ_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)))
                                                  break;
                                  }
                                  IF_ADDR_RUNLOCK(ifp);
                                  if (ifa != NULL)
                                          /* No LLA is configured. */
                                          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 in6_ifaddr *ia, *ia_next;
                  struct nd_prefix *pr, *next;
                  struct nd_prhead prl;
  
                  LIST_INIT(&prl);
  
                  ND6_WLOCK();
                  LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, next) {
                          if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
                                  continue; /* XXX */
                          nd6_prefix_unlink(pr, &prl);
                  }
                  ND6_WUNLOCK();
  
                  while ((pr = LIST_FIRST(&prl)) != NULL) {
                          LIST_REMOVE(pr, ndpr_entry);
                          /* XXXRW: in6_ifaddrhead locking. */
                          CK_STAILQ_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);
                          }
                          nd6_prefix_del(pr);
                  }
                  break;
          }
          case SIOCSRTRFLUSH_IN6:
          {
                  /* flush all the default routers */
                  struct nd_drhead drq;
                  struct nd_defrouter *dr;
  
                  TAILQ_INIT(&drq);
  
                  defrouter_reset();
  
                  ND6_WLOCK();
                  while ((dr = TAILQ_FIRST(&V_nd_defrouter)) != NULL)
                          defrouter_unlink(dr, &drq);
                  ND6_WUNLOCK();
                  while ((dr = TAILQ_FIRST(&drq)) != NULL) {
                          TAILQ_REMOVE(&drq, dr, dr_entry);
                          defrouter_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 + ln->lle_remtime / hz +
                              (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);
  }
  
  /*
   * Calculates new isRouter value based on provided parameters and
   * returns it.
   */
  static int
  nd6_is_router(int type, int code, int is_new, int old_addr, int new_addr,
      int ln_router)
  {
  
          /*
           * 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.
           *
           *   is_new  old_addr new_addr      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       (4)     c   s     s
           *      0       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_new)                                     /* (6-7) */
                          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_router = 1;
                  else {
                          if (is_new)                             /* (6-7) */
                                  ln_router = 0;
                  }
                  break;
          case ND_ROUTER_SOLICIT:
                  /*
                   * is_router flag must always be cleared.
                   */
                  ln_router = 0;
                  break;
          case ND_ROUTER_ADVERT:
                  /*
                   * Mark an entry with lladdr as a router.
                   */
                  if ((!is_new && (old_addr || new_addr)) ||      /* (2-5) */
                      (is_new && new_addr)) {                     /* (7) */
                          ln_router = 1;
                  }
                  break;
          }
  
          return (ln_router);
  }
  
  /*
   * 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
   *
   */
  void
  nd6_cache_lladdr(struct ifnet *ifp, struct in6_addr *from, char *lladdr,
      int lladdrlen, int type, int code)
  {
          struct llentry *ln = NULL, *ln_tmp;
          int is_newentry;
          int do_update;
          int olladdr;
          int llchange;
          int flags;
          uint16_t router = 0;
          struct sockaddr_in6 sin6;
          struct mbuf *chain = NULL;
          u_char linkhdr[LLE_MAX_LINKHDR];
          size_t linkhdrsize;
          int lladdr_off;
  
          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;
  
          /*
           * 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 ? LLE_EXCLUSIVE : 0;
          IF_AFDATA_RLOCK(ifp);
          ln = nd6_lookup(from, flags, ifp);
          IF_AFDATA_RUNLOCK(ifp);
          is_newentry = 0;
          if (ln == NULL) {
                  flags |= LLE_EXCLUSIVE;
                  ln = nd6_alloc(from, 0, ifp);
                  if (ln == NULL)
                          return;
  
                  /*
                   * Since we already know all the data for the new entry,
                   * fill it before insertion.
                   */
                  if (lladdr != NULL) {
                          linkhdrsize = sizeof(linkhdr);
                          if (lltable_calc_llheader(ifp, AF_INET6, lladdr,
                              linkhdr, &linkhdrsize, &lladdr_off) != 0)
                                  return;
                          lltable_set_entry_addr(ifp, ln, linkhdr, linkhdrsize,
                              lladdr_off);
                  }
  
                  IF_AFDATA_WLOCK(ifp);
                  LLE_WLOCK(ln);
                  /* Prefer any existing lle over newly-created one */
                  ln_tmp = nd6_lookup(from, LLE_EXCLUSIVE, ifp);
                  if (ln_tmp == NULL)
                          lltable_link_entry(LLTABLE6(ifp), ln);
                  IF_AFDATA_WUNLOCK(ifp);
                  if (ln_tmp == NULL) {
                          /* No existing lle, mark as new entry (6,7) */
                          is_newentry = 1;
                          if (lladdr != NULL) {   /* (7) */
                                  nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
                                  EVENTHANDLER_INVOKE(lle_event, ln,
                                      LLENTRY_RESOLVED);
                          }
                  } else {
                          lltable_free_entry(LLTABLE6(ifp), ln);
                          ln = ln_tmp;
                          ln_tmp = NULL;
                  }
          } 
          /* do nothing if static ndp is set */
          if ((ln->la_flags & LLE_STATIC)) {
                  if (flags & LLE_EXCLUSIVE)
                          LLE_WUNLOCK(ln);
                  else
                          LLE_RUNLOCK(ln);
                  return;
          }
  
          olladdr = (ln->la_flags & LLE_VALID) ? 1 : 0;
          if (olladdr && lladdr) {
                  llchange = bcmp(lladdr, ln->ll_addr,
                      ifp->if_addrlen);
          } else if (!olladdr && lladdr)
                  llchange = 1;
          else
                  llchange = 0;
  
          /*
           * newentry olladdr  lladdr  llchange   (*=record)
           *      0       n       n       --      (1)
           *      0       y       n       --      (2)
           *      0       n       y       y       (3) * STALE
           *      0       y       y       n       (4) *
           *      0       y       y       y       (5) * STALE
           *      1       --      n       --      (6)   NOSTATE(= PASSIVE)
           *      1       --      y       --      (7) * STALE
           */
  
          do_update = 0;
          if (is_newentry == 0 && llchange != 0) {
                  do_update = 1;  /* (3,5) */
  
                  /*
                   * Record source link-layer address
                   * XXX is it dependent to ifp->if_type?
                   */
                  linkhdrsize = sizeof(linkhdr);
                  if (lltable_calc_llheader(ifp, AF_INET6, lladdr,
                      linkhdr, &linkhdrsize, &lladdr_off) != 0)
                          return;
  
                  if (lltable_try_set_entry_addr(ifp, ln, linkhdr, linkhdrsize,
                      lladdr_off) == 0) {
                          /* Entry was deleted */
                          return;
                  }
  
                  nd6_llinfo_setstate(ln, ND6_LLINFO_STALE);
  
                  EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
  
                  if (ln->la_hold != NULL)
                          nd6_grab_holdchain(ln, &chain, &sin6);
          }
  
          /* Calculates new router status */
          router = nd6_is_router(type, code, is_newentry, olladdr,
              lladdr != NULL ? 1 : 0, ln->ln_router);
  
          ln->ln_router = router;
          /* Mark non-router redirects with special flag */
          if ((type & 0xFF) == ND_REDIRECT && code != ND_REDIRECT_ROUTER)
                  ln->la_flags |= LLE_REDIRECT;
  
          if (flags & LLE_EXCLUSIVE)
                  LLE_WUNLOCK(ln);
          else
                  LLE_RUNLOCK(ln);
  
          if (chain != NULL)
                  nd6_flush_holdchain(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_fib() 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_fib() should not have a bad effect
           * for those are not autoconfigured hosts, we explicitly avoid such
           * cases for safety.
           */
          if ((do_update || is_newentry) && router &&
              ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
                  /*
                   * guaranteed recursion
                   */
                  defrouter_select_fib(ifp->if_fib);
          }
  }
  
  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();
          CK_STAILQ_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;
          lltable_fill_sa_entry(ln, (struct sockaddr *)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)
                   */
                  nd6_llinfo_setstate(ln, ND6_LLINFO_DELAY);
          }
  }
  
  int
  nd6_output_ifp(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
      struct sockaddr_in6 *dst, struct route *ro)
  {
          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, ro);
          return (error);
  }
  
  /*
   * Lookup link headerfor @sa_dst address. Stores found
   * data in @desten buffer. Copy of lle ln_flags can be also
   * saved in @pflags if @pflags is non-NULL.
   *
   * If destination LLE does not exists or lle state modification
   * is required, call "slow" version.
   *
   * Return values:
   * - 0 on success (address copied to buffer).
   * - EWOULDBLOCK (no local error, but address is still unresolved)
   * - other errors (alloc failure, etc)
   */
  int
  nd6_resolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
      const struct sockaddr *sa_dst, u_char *desten, uint32_t *pflags,
      struct llentry **plle)
  {
          struct llentry *ln = NULL;
          const struct sockaddr_in6 *dst6;
  
          if (pflags != NULL)
                  *pflags = 0;
  
          dst6 = (const struct sockaddr_in6 *)sa_dst;
  
          /* 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 (m != NULL && m->m_flags & M_MCAST) {
                  switch (ifp->if_type) {
                  case IFT_ETHER:
                  case IFT_L2VLAN:
                  case IFT_BRIDGE:
                          ETHER_MAP_IPV6_MULTICAST(&dst6->sin6_addr,
                                                   desten);
                          return (0);
                  default:
                          m_freem(m);
                          return (EAFNOSUPPORT);
                  }
          }
  
          IF_AFDATA_RLOCK(ifp);
          ln = nd6_lookup(&dst6->sin6_addr, plle ? LLE_EXCLUSIVE : LLE_UNLOCKED,
              ifp);
          if (ln != NULL && (ln->r_flags & RLLE_VALID) != 0) {
                  /* Entry found, let's copy lle info */
                  bcopy(ln->r_linkdata, desten, ln->r_hdrlen);
                  if (pflags != NULL)
                          *pflags = LLE_VALID | (ln->r_flags & RLLE_IFADDR);
                  /* Check if we have feedback request from nd6 timer */
                  if (ln->r_skip_req != 0) {
                          LLE_REQ_LOCK(ln);
                          ln->r_skip_req = 0; /* Notify that entry was used */
                          ln->lle_hittime = time_uptime;
                          LLE_REQ_UNLOCK(ln);
                  }
                  if (plle) {
                          LLE_ADDREF(ln);
                          *plle = ln;
                          LLE_WUNLOCK(ln);
                  }
                  IF_AFDATA_RUNLOCK(ifp);
                  return (0);
          } else if (plle && ln)
                  LLE_WUNLOCK(ln);
          IF_AFDATA_RUNLOCK(ifp);
  
          return (nd6_resolve_slow(ifp, 0, m, dst6, desten, pflags, plle));
  }
  
  
  /*
   * Do L2 address resolution for @sa_dst address. Stores found
   * address in @desten buffer. Copy of lle ln_flags can be also
   * saved in @pflags if @pflags is non-NULL.
   *
   * Heavy version.
   * Function assume that destination LLE does not exist,
   * is invalid or stale, so LLE_EXCLUSIVE lock needs to be acquired.
   *
   * Set noinline to be dtrace-friendly
   */
  static __noinline int
  nd6_resolve_slow(struct ifnet *ifp, int flags, struct mbuf *m,
      const struct sockaddr_in6 *dst, u_char *desten, uint32_t *pflags,
      struct llentry **plle)
  {
          struct llentry *lle = NULL, *lle_tmp;
          struct in6_addr *psrc, src;
          int send_ns, ll_len;
          char *lladdr;
  
          /*
           * 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, LLE_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.
                           */
                          lle = nd6_alloc(&dst->sin6_addr, 0, ifp);
                          if (lle == NULL) {
                                  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);
                          }
  
                          IF_AFDATA_WLOCK(ifp);
                          LLE_WLOCK(lle);
                          /* Prefer any existing entry over newly-created one */
                          lle_tmp = nd6_lookup(&dst->sin6_addr, LLE_EXCLUSIVE, ifp);
                          if (lle_tmp == NULL)
                                  lltable_link_entry(LLTABLE6(ifp), lle);
                          IF_AFDATA_WUNLOCK(ifp);
                          if (lle_tmp != NULL) {
                                  lltable_free_entry(LLTABLE6(ifp), lle);
                                  lle = lle_tmp;
                                  lle_tmp = NULL;
                          }
                  }
          } 
          if (lle == NULL) {
                  if (!(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) {
                          m_freem(m);
                          return (ENOBUFS);
                  }
  
                  if (m != NULL)
                          m_freem(m);
                  return (ENOBUFS);
          }
  
          LLE_WLOCK_ASSERT(lle);
  
          /*
           * 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)
                  nd6_llinfo_setstate(lle, ND6_LLINFO_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 (lle->ln_state > ND6_LLINFO_INCOMPLETE) {
                  if (flags & LLE_ADDRONLY) {
                          lladdr = lle->ll_addr;
                          ll_len = ifp->if_addrlen;
                  } else {
                          lladdr = lle->r_linkdata;
                          ll_len = lle->r_hdrlen;
                  }
                  bcopy(lladdr, desten, ll_len);
                  if (pflags != NULL)
                          *pflags = lle->la_flags;
                  if (plle) {
                          LLE_ADDREF(lle);
                          *plle = lle;
                  }
                  LLE_WUNLOCK(lle);
                  return (0);
          }
  
          /*
           * 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.  When it exceeds nd6_maxqueuelen,
           * the oldest packet in the queue will be removed.
           */
  
          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.
           * Note that for newly-created lle la_asked will be 0,
           * so we will transition from ND6_LLINFO_NOSTATE to
           * ND6_LLINFO_INCOMPLETE state here.
           */
          psrc = NULL;
          send_ns = 0;
          if (lle->la_asked == 0) {
                  lle->la_asked++;
                  send_ns = 1;
                  psrc = nd6_llinfo_get_holdsrc(lle, &src);
  
                  nd6_llinfo_setstate(lle, ND6_LLINFO_INCOMPLETE);
          }
          LLE_WUNLOCK(lle);
          if (send_ns != 0)
                  nd6_ns_output(ifp, psrc, NULL, &dst->sin6_addr, NULL);
  
          return (EWOULDBLOCK);
  }
  
  /*
   * Do L2 address resolution for @sa_dst address. Stores found
   * address in @desten buffer. Copy of lle ln_flags can be also
   * saved in @pflags if @pflags is non-NULL.
   *
   * Return values:
   * - 0 on success (address copied to buffer).
   * - EWOULDBLOCK (no local error, but address is still unresolved)
   * - other errors (alloc failure, etc)
   */
  int
  nd6_resolve_addr(struct ifnet *ifp, int flags, const struct sockaddr *dst,
      char *desten, uint32_t *pflags)
  {
          int error;
  
          flags |= LLE_ADDRONLY;
          error = nd6_resolve_slow(ifp, flags, NULL,
              (const struct sockaddr_in6 *)dst, desten, pflags, NULL);
          return (error);
  }
  
  int
  nd6_flush_holdchain(struct ifnet *ifp, struct mbuf *chain,
      struct sockaddr_in6 *dst)
  {
          struct mbuf *m, *m_head;
          int error = 0;
  
          m_head = chain;
  
          while (m_head) {
                  m = m_head;
                  m_head = m_head->m_nextpkt;
                  error = nd6_output_ifp(ifp, ifp, m, dst, NULL);
          }
  
          /*
           * XXX
           * note that intermediate errors are blindly ignored
           */
          return (error);
  }
  
  static int
  nd6_need_cache(struct ifnet *ifp)
  {
          /*
           * XXX: we currently do not make neighbor cache on any interface
           * other than Ethernet and GIF.
           *
           * RFC2893 says:
           * - unidirectional tunnels needs no ND
           */
          switch (ifp->if_type) {
          case IFT_ETHER:
          case IFT_IEEE1394:
          case IFT_L2VLAN:
          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, *ln_tmp;
          struct sockaddr *dst;
  
          ifp = ia->ia_ifa.ifa_ifp;
          if (nd6_need_cache(ifp) == 0)
                  return (0);
  
          ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
          dst = (struct sockaddr *)&ia->ia_addr;
          ln = lltable_alloc_entry(LLTABLE6(ifp), LLE_IFADDR, dst);
          if (ln == NULL)
                  return (ENOBUFS);
  
          IF_AFDATA_WLOCK(ifp);
          LLE_WLOCK(ln);
          /* Unlink any entry if exists */
          ln_tmp = lla_lookup(LLTABLE6(ifp), LLE_EXCLUSIVE, dst);
          if (ln_tmp != NULL)
                  lltable_unlink_entry(LLTABLE6(ifp), ln_tmp);
          lltable_link_entry(LLTABLE6(ifp), ln);
          IF_AFDATA_WUNLOCK(ifp);
  
          if (ln_tmp != NULL)
                  EVENTHANDLER_INVOKE(lle_event, ln_tmp, LLENTRY_EXPIRED);
          EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
  
          LLE_WUNLOCK(ln);
          if (ln_tmp != NULL)
                  llentry_free(ln_tmp);
  
          return (0);
  }
  
  /*
   * Removes either all lle entries for given @ia, or lle
   * corresponding to @ia address.
   */
  void
  nd6_rem_ifa_lle(struct in6_ifaddr *ia, int all)
  {
          struct sockaddr_in6 mask, addr;
          struct sockaddr *saddr, *smask;
          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));
          saddr = (struct sockaddr *)&addr;
          smask = (struct sockaddr *)&mask;
  
          if (all != 0)
                  lltable_prefix_free(AF_INET6, saddr, smask, LLE_STATIC);
          else
                  lltable_delete_addr(LLTABLE6(ifp), LLE_IFADDR, saddr);
  }
  
  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;
  }
  
  static int nd6_sysctl_drlist(SYSCTL_HANDLER_ARGS);
  static int nd6_sysctl_prlist(SYSCTL_HANDLER_ARGS);
  
  SYSCTL_DECL(_net_inet6_icmp6);
  SYSCTL_PROC(_net_inet6_icmp6, ICMPV6CTL_ND6_DRLIST, nd6_drlist,
          CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE,
          NULL, 0, nd6_sysctl_drlist, "S,in6_defrouter",
          "NDP default router list");
  SYSCTL_PROC(_net_inet6_icmp6, ICMPV6CTL_ND6_PRLIST, nd6_prlist,
          CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE,
          NULL, 0, nd6_sysctl_prlist, "S,in6_prefix",
          "NDP prefix list");
  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 != NULL)
                  return (EPERM);
  
          error = sysctl_wire_old_buffer(req, 0);
          if (error != 0)
                  return (error);
  
          bzero(&d, sizeof(d));
          d.rtaddr.sin6_family = AF_INET6;
          d.rtaddr.sin6_len = sizeof(d.rtaddr);
  
          ND6_RLOCK();
          TAILQ_FOREACH(dr, &V_nd_defrouter, dr_entry) {
                  d.rtaddr.sin6_addr = dr->rtaddr;
                  error = sa6_recoverscope(&d.rtaddr);
                  if (error != 0)
                          break;
                  d.flags = dr->raflags;
                  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)
                          break;
          }
          ND6_RUNLOCK();
          return (error);
  }
  
  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);
  
          error = sysctl_wire_old_buffer(req, 0);
          if (error != 0)
                  return (error);
  
          bzero(&p, sizeof(p));
          p.origin = PR_ORIG_RA;
          bzero(&s6, sizeof(s6));
          s6.sin6_family = AF_INET6;
          s6.sin6_len = sizeof(s6);
  
          ND6_RLOCK();
          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_addrcnt;
                  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)
                          break;
                  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)
                                  goto out;
                  }
          }
  out:
          ND6_RUNLOCK();
          return (error);
  }

Cache object: 18b95332daad55ac75013f4b635ddee1