FreeBSD/Linux Kernel Cross Reference
sys/netinet6/nd6_rtr.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_rtr.c,v 1.111 2001/04/27 01:37:15 jinmei Exp $
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/refcount.h>
    #include <sys/socket.h>
    #include <sys/sockio.h>
    #include <sys/time.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/errno.h>
    #include <sys/rmlock.h>
    #include <sys/rwlock.h>
    #include <sys/sysctl.h>
    #include <sys/syslog.h>
    #include <sys/queue.h>
    
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_types.h>
    #include <net/if_dl.h>
    #include <net/route.h>
    #include <net/route/nhop.h>
    #include <net/route/route_ctl.h>
    #include <net/radix.h>
    #include <net/vnet.h>
    
    #include <netinet/in.h>
    #include <net/if_llatbl.h>
    #include <netinet6/in6_var.h>
    #include <netinet6/in6_ifattach.h>
    #include <netinet/ip6.h>
    #include <netinet6/ip6_var.h>
    #include <netinet6/nd6.h>
    #include <netinet/icmp6.h>
    #include <netinet6/scope6_var.h>
    
    static struct nd_defrouter *defrtrlist_update(struct nd_defrouter *);
    static int prelist_update(struct nd_prefixctl *, struct nd_defrouter *,
        struct mbuf *, int);
    static int nd6_prefix_onlink(struct nd_prefix *);
    
    TAILQ_HEAD(nd6_drhead, nd_defrouter);
    VNET_DEFINE_STATIC(struct nd6_drhead, nd6_defrouter);
    #define V_nd6_defrouter                 VNET(nd6_defrouter)
    
    VNET_DECLARE(int, nd6_recalc_reachtm_interval);
    #define V_nd6_recalc_reachtm_interval   VNET(nd6_recalc_reachtm_interval)
    
    VNET_DEFINE_STATIC(struct ifnet *, nd6_defifp);
    VNET_DEFINE(int, nd6_defifindex);
    #define V_nd6_defifp                    VNET(nd6_defifp)
    
    VNET_DEFINE(int, ip6_use_tempaddr) = 0;
    
    VNET_DEFINE(int, ip6_desync_factor);
    VNET_DEFINE(u_int32_t, ip6_temp_preferred_lifetime) = DEF_TEMP_PREFERRED_LIFETIME;
    VNET_DEFINE(u_int32_t, ip6_temp_valid_lifetime) = DEF_TEMP_VALID_LIFETIME;
    
    VNET_DEFINE(int, ip6_temp_regen_advance) = TEMPADDR_REGEN_ADVANCE;
   
   #ifdef EXPERIMENTAL
   VNET_DEFINE(int, nd6_ignore_ipv6_only_ra) = 1;
   #endif
   
   SYSCTL_DECL(_net_inet6_icmp6);
   
   /* RTPREF_MEDIUM has to be 0! */
   #define RTPREF_HIGH     1
   #define RTPREF_MEDIUM   0
   #define RTPREF_LOW      (-1)
   #define RTPREF_RESERVED (-2)
   #define RTPREF_INVALID  (-3)    /* internal */
   
   static void
   defrouter_ref(struct nd_defrouter *dr)
   {
   
           refcount_acquire(&dr->refcnt);
   }
   
   void
   defrouter_rele(struct nd_defrouter *dr)
   {
   
           if (refcount_release(&dr->refcnt))
                   free(dr, M_IP6NDP);
   }
   
   /*
    * Remove a router from the global list and optionally stash it in a
    * caller-supplied queue.
    */
   static void
   defrouter_unlink(struct nd_defrouter *dr, struct nd6_drhead *drq)
   {
   
           ND6_WLOCK_ASSERT();
   
           TAILQ_REMOVE(&V_nd6_defrouter, dr, dr_entry);
           V_nd6_list_genid++;
           if (drq != NULL)
                   TAILQ_INSERT_TAIL(drq, dr, dr_entry);
   }
   
   /*
    * Receive Router Solicitation Message - just for routers.
    * Router solicitation/advertisement is mostly managed by userland program
    * (rtadvd) so here we have no function like nd6_ra_output().
    *
    * Based on RFC 2461
    */
   void
   nd6_rs_input(struct mbuf *m, int off, int icmp6len)
   {
           struct ifnet *ifp;
           struct ip6_hdr *ip6;
           struct nd_router_solicit *nd_rs;
           struct in6_addr saddr6;
           union nd_opts ndopts;
           char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
           char *lladdr;
           int lladdrlen;
   
           ifp = m->m_pkthdr.rcvif;
   
           /*
            * Accept RS only when V_ip6_forwarding=1 and the interface has
            * no ND6_IFF_ACCEPT_RTADV.
            */
           if (!V_ip6_forwarding || ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV)
                   goto freeit;
   
           /* RFC 6980: Nodes MUST silently ignore fragments */   
           if(m->m_flags & M_FRAGMENTED)
                   goto freeit;
   
           /* Sanity checks */
           ip6 = mtod(m, struct ip6_hdr *);
           if (__predict_false(ip6->ip6_hlim != 255)) {
                   ICMP6STAT_INC(icp6s_invlhlim);
                   nd6log((LOG_ERR,
                       "%s: invalid hlim (%d) from %s to %s on %s\n", __func__,
                       ip6->ip6_hlim, ip6_sprintf(ip6bufs, &ip6->ip6_src),
                       ip6_sprintf(ip6bufd, &ip6->ip6_dst), if_name(ifp)));
                   goto bad;
           }
   
           /*
            * Don't update the neighbor cache, if src = ::.
            * This indicates that the src has no IP address assigned yet.
            */
           saddr6 = ip6->ip6_src;
           if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
                   goto freeit;
   
           if (m->m_len < off + icmp6len) {
                   m = m_pullup(m, off + icmp6len);
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           return;
                   }
           }
           ip6 = mtod(m, struct ip6_hdr *);
           nd_rs = (struct nd_router_solicit *)((caddr_t)ip6 + off);
   
           icmp6len -= sizeof(*nd_rs);
           nd6_option_init(nd_rs + 1, icmp6len, &ndopts);
           if (nd6_options(&ndopts) < 0) {
                   nd6log((LOG_INFO,
                       "%s: invalid ND option, ignored\n", __func__));
                   /* nd6_options have incremented stats */
                   goto freeit;
           }
   
           lladdr = NULL;
           lladdrlen = 0;
           if (ndopts.nd_opts_src_lladdr) {
                   lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
                   lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
           }
   
           if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
                   nd6log((LOG_INFO,
                       "%s: lladdrlen mismatch for %s (if %d, RS packet %d)\n",
                       __func__, ip6_sprintf(ip6bufs, &saddr6),
                       ifp->if_addrlen, lladdrlen - 2));
                   goto bad;
           }
   
           nd6_cache_lladdr(ifp, &saddr6, lladdr, lladdrlen, ND_ROUTER_SOLICIT, 0);
   
    freeit:
           m_freem(m);
           return;
   
    bad:
           ICMP6STAT_INC(icp6s_badrs);
           m_freem(m);
   }
   
   #ifdef EXPERIMENTAL
   /*
    * An initial update routine for draft-ietf-6man-ipv6only-flag.
    * We need to iterate over all default routers for the given
    * interface to see whether they are all advertising the "S"
    * (IPv6-Only) flag.  If they do set, otherwise unset, the
    * interface flag we later use to filter on.
    */
   static void
   defrtr_ipv6_only_ifp(struct ifnet *ifp)
   {
           struct nd_defrouter *dr;
           bool ipv6_only, ipv6_only_old;
   #ifdef INET
           struct epoch_tracker et;
           struct ifaddr *ifa;
           bool has_ipv4_addr;
   #endif
   
           if (V_nd6_ignore_ipv6_only_ra != 0)
                   return;
   
           ipv6_only = true;
           ND6_RLOCK();
           TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry)
                   if (dr->ifp == ifp &&
                       (dr->raflags & ND_RA_FLAG_IPV6_ONLY) == 0)
                           ipv6_only = false;
           ND6_RUNLOCK();
   
           IF_AFDATA_WLOCK(ifp);
           ipv6_only_old = ND_IFINFO(ifp)->flags & ND6_IFF_IPV6_ONLY;
           IF_AFDATA_WUNLOCK(ifp);
   
           /* If nothing changed, we have an early exit. */
           if (ipv6_only == ipv6_only_old)
                   return;
   
   #ifdef INET
           /*
            * Should we want to set the IPV6-ONLY flag, check if the
            * interface has a non-0/0 and non-link-local IPv4 address
            * configured on it.  If it has we will assume working
            * IPv4 operations and will clear the interface flag.
            */
           has_ipv4_addr = false;
           if (ipv6_only) {
                   NET_EPOCH_ENTER(et);
                   CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                           if (ifa->ifa_addr->sa_family != AF_INET)
                                   continue;
                           if (in_canforward(
                               satosin(ifa->ifa_addr)->sin_addr)) {
                                   has_ipv4_addr = true;
                                   break;
                           }
                   }
                   NET_EPOCH_EXIT(et);
           }
           if (ipv6_only && has_ipv4_addr) {
                   log(LOG_NOTICE, "%s rcvd RA w/ IPv6-Only flag set but has IPv4 "
                       "configured, ignoring IPv6-Only flag.\n", ifp->if_xname);
                   ipv6_only = false;
           }
   #endif
   
           IF_AFDATA_WLOCK(ifp);
           if (ipv6_only)
                   ND_IFINFO(ifp)->flags |= ND6_IFF_IPV6_ONLY;
           else
                   ND_IFINFO(ifp)->flags &= ~ND6_IFF_IPV6_ONLY;
           IF_AFDATA_WUNLOCK(ifp);
   
   #ifdef notyet
           /* Send notification of flag change. */
   #endif
   }
   
   static void
   defrtr_ipv6_only_ipf_down(struct ifnet *ifp)
   {
   
           IF_AFDATA_WLOCK(ifp);
           ND_IFINFO(ifp)->flags &= ~ND6_IFF_IPV6_ONLY;
           IF_AFDATA_WUNLOCK(ifp);
   }
   #endif  /* EXPERIMENTAL */
   
   void
   nd6_ifnet_link_event(void *arg __unused, struct ifnet *ifp, int linkstate)
   {
   
           /*
            * XXX-BZ we might want to trigger re-evaluation of our default router
            * availability. E.g., on link down the default router might be
            * unreachable but a different interface might still have connectivity.
            */
   
   #ifdef EXPERIMENTAL
           if (linkstate == LINK_STATE_DOWN)
                   defrtr_ipv6_only_ipf_down(ifp);
   #endif
   }
   
   /*
    * Receive Router Advertisement Message.
    *
    * Based on RFC 2461
    * TODO: on-link bit on prefix information
    * TODO: ND_RA_FLAG_{OTHER,MANAGED} processing
    */
   void
   nd6_ra_input(struct mbuf *m, int off, int icmp6len)
   {
           struct ifnet *ifp;
           struct nd_ifinfo *ndi;
           struct ip6_hdr *ip6;
           struct nd_router_advert *nd_ra;
           struct in6_addr saddr6;
           struct nd_defrouter *dr;
           union nd_opts ndopts;
           char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
           int mcast;
   
           /*
            * We only accept RAs only when the per-interface flag
            * ND6_IFF_ACCEPT_RTADV is on the receiving interface.
            */
           ifp = m->m_pkthdr.rcvif;
           ndi = ND_IFINFO(ifp);
           if (!(ndi->flags & ND6_IFF_ACCEPT_RTADV))
                   goto freeit;
   
           /* RFC 6980: Nodes MUST silently ignore fragments */
           if(m->m_flags & M_FRAGMENTED)
                   goto freeit;
   
           ip6 = mtod(m, struct ip6_hdr *);
           if (__predict_false(ip6->ip6_hlim != 255)) {
                   ICMP6STAT_INC(icp6s_invlhlim);
                   nd6log((LOG_ERR,
                       "%s: invalid hlim (%d) from %s to %s on %s\n", __func__,
                       ip6->ip6_hlim, ip6_sprintf(ip6bufs, &ip6->ip6_src),
                       ip6_sprintf(ip6bufd, &ip6->ip6_dst), if_name(ifp)));
                   goto bad;
           }
   
           saddr6 = ip6->ip6_src;
           if (!IN6_IS_ADDR_LINKLOCAL(&saddr6)) {
                   nd6log((LOG_ERR,
                       "%s: src %s is not link-local\n", __func__,
                       ip6_sprintf(ip6bufs, &saddr6)));
                   goto bad;
           }
   
           if (m->m_len < off + icmp6len) {
                   m = m_pullup(m, off + icmp6len);
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           return;
                   }
           }
           ip6 = mtod(m, struct ip6_hdr *);
           nd_ra = (struct nd_router_advert *)((caddr_t)ip6 + off);
   
           icmp6len -= sizeof(*nd_ra);
           nd6_option_init(nd_ra + 1, icmp6len, &ndopts);
           if (nd6_options(&ndopts) < 0) {
                   nd6log((LOG_INFO,
                       "%s: invalid ND option, ignored\n", __func__));
                   /* nd6_options have incremented stats */
                   goto freeit;
           }
   
           mcast = 0;
           dr = NULL;
       {
           struct nd_defrouter dr0;
           u_int32_t advreachable = nd_ra->nd_ra_reachable;
   
           /* remember if this is a multicasted advertisement */
           if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))
                   mcast = 1;
   
           bzero(&dr0, sizeof(dr0));
           dr0.rtaddr = saddr6;
           dr0.raflags = nd_ra->nd_ra_flags_reserved;
           /*
            * Effectively-disable routes from RA messages when
            * ND6_IFF_NO_RADR enabled on the receiving interface or
            * (ip6.forwarding == 1 && ip6.rfc6204w3 != 1).
            */
           if (ndi->flags & ND6_IFF_NO_RADR)
                   dr0.rtlifetime = 0;
           else if (V_ip6_forwarding && !V_ip6_rfc6204w3)
                   dr0.rtlifetime = 0;
           else
                   dr0.rtlifetime = ntohs(nd_ra->nd_ra_router_lifetime);
           dr0.expire = time_uptime + dr0.rtlifetime;
           dr0.ifp = ifp;
           /* unspecified or not? (RFC 2461 6.3.4) */
           if (advreachable) {
                   advreachable = ntohl(advreachable);
                   if (advreachable <= MAX_REACHABLE_TIME &&
                       ndi->basereachable != advreachable) {
                           ndi->basereachable = advreachable;
                           ndi->reachable = ND_COMPUTE_RTIME(ndi->basereachable);
                           ndi->recalctm = V_nd6_recalc_reachtm_interval; /* reset */
                   }
           }
           if (nd_ra->nd_ra_retransmit)
                   ndi->retrans = ntohl(nd_ra->nd_ra_retransmit);
           if (nd_ra->nd_ra_curhoplimit) {
                   if (ndi->chlim < nd_ra->nd_ra_curhoplimit)
                           ndi->chlim = nd_ra->nd_ra_curhoplimit;
                   else if (ndi->chlim != nd_ra->nd_ra_curhoplimit) {
                           log(LOG_ERR, "RA with a lower CurHopLimit sent from "
                               "%s on %s (current = %d, received = %d). "
                               "Ignored.\n", ip6_sprintf(ip6bufs, &ip6->ip6_src),
                               if_name(ifp), ndi->chlim, nd_ra->nd_ra_curhoplimit);
                   }
           }
           dr = defrtrlist_update(&dr0);
   #ifdef EXPERIMENTAL
           defrtr_ipv6_only_ifp(ifp);
   #endif
       }
   
           /*
            * prefix
            */
           if (ndopts.nd_opts_pi) {
                   struct nd_opt_hdr *pt;
                   struct nd_opt_prefix_info *pi = NULL;
                   struct nd_prefixctl pr;
   
                   for (pt = (struct nd_opt_hdr *)ndopts.nd_opts_pi;
                        pt <= (struct nd_opt_hdr *)ndopts.nd_opts_pi_end;
                        pt = (struct nd_opt_hdr *)((caddr_t)pt +
                                                   (pt->nd_opt_len << 3))) {
                           if (pt->nd_opt_type != ND_OPT_PREFIX_INFORMATION)
                                   continue;
                           pi = (struct nd_opt_prefix_info *)pt;
   
                           if (pi->nd_opt_pi_len != 4) {
                                   nd6log((LOG_INFO,
                                       "%s: invalid option len %d for prefix "
                                       "information option, ignored\n", __func__,
                                       pi->nd_opt_pi_len));
                                   continue;
                           }
   
                           if (128 < pi->nd_opt_pi_prefix_len) {
                                   nd6log((LOG_INFO,
                                       "%s: invalid prefix len %d for prefix "
                                       "information option, ignored\n", __func__,
                                       pi->nd_opt_pi_prefix_len));
                                   continue;
                           }
   
                           if (IN6_IS_ADDR_MULTICAST(&pi->nd_opt_pi_prefix)
                            || IN6_IS_ADDR_LINKLOCAL(&pi->nd_opt_pi_prefix)) {
                                   nd6log((LOG_INFO,
                                       "%s: invalid prefix %s, ignored\n",
                                       __func__, ip6_sprintf(ip6bufs,
                                           &pi->nd_opt_pi_prefix)));
                                   continue;
                           }
   
                           bzero(&pr, sizeof(pr));
                           pr.ndpr_prefix.sin6_family = AF_INET6;
                           pr.ndpr_prefix.sin6_len = sizeof(pr.ndpr_prefix);
                           pr.ndpr_prefix.sin6_addr = pi->nd_opt_pi_prefix;
                           pr.ndpr_ifp = (struct ifnet *)m->m_pkthdr.rcvif;
   
                           pr.ndpr_raf_onlink = (pi->nd_opt_pi_flags_reserved &
                               ND_OPT_PI_FLAG_ONLINK) ? 1 : 0;
                           pr.ndpr_raf_auto = (pi->nd_opt_pi_flags_reserved &
                               ND_OPT_PI_FLAG_AUTO) ? 1 : 0;
                           pr.ndpr_raf_ra_derived = 1;
                           pr.ndpr_plen = pi->nd_opt_pi_prefix_len;
                           pr.ndpr_vltime = ntohl(pi->nd_opt_pi_valid_time);
                           pr.ndpr_pltime = ntohl(pi->nd_opt_pi_preferred_time);
                           (void)prelist_update(&pr, dr, m, mcast);
                   }
           }
           if (dr != NULL) {
                   defrouter_rele(dr);
                   dr = NULL;
           }
   
           /*
            * MTU
            */
           if (ndopts.nd_opts_mtu && ndopts.nd_opts_mtu->nd_opt_mtu_len == 1) {
                   u_long mtu;
                   u_long maxmtu;
   
                   mtu = (u_long)ntohl(ndopts.nd_opts_mtu->nd_opt_mtu_mtu);
   
                   /* lower bound */
                   if (mtu < IPV6_MMTU) {
                           nd6log((LOG_INFO, "%s: bogus mtu option mtu=%lu sent "
                               "from %s, ignoring\n", __func__,
                               mtu, ip6_sprintf(ip6bufs, &ip6->ip6_src)));
                           goto skip;
                   }
   
                   /* upper bound */
                   maxmtu = (ndi->maxmtu && ndi->maxmtu < ifp->if_mtu)
                       ? ndi->maxmtu : ifp->if_mtu;
                   if (mtu <= maxmtu) {
                           int change = (ndi->linkmtu != mtu);
   
                           ndi->linkmtu = mtu;
                           if (change) {
                                   /* in6_maxmtu may change */
                                   in6_setmaxmtu();
                                   rt_updatemtu(ifp);
                           }
                   } else {
                           nd6log((LOG_INFO, "%s: bogus mtu=%lu sent from %s; "
                               "exceeds maxmtu %lu, ignoring\n", __func__,
                               mtu, ip6_sprintf(ip6bufs, &ip6->ip6_src), maxmtu));
                   }
           }
   
    skip:
   
           /*
            * Source link layer address
            */
       {
           char *lladdr = NULL;
           int lladdrlen = 0;
   
           if (ndopts.nd_opts_src_lladdr) {
                   lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
                   lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
           }
   
           if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
                   nd6log((LOG_INFO,
                       "%s: lladdrlen mismatch for %s (if %d, RA packet %d)\n",
                       __func__, ip6_sprintf(ip6bufs, &saddr6),
                       ifp->if_addrlen, lladdrlen - 2));
                   goto bad;
           }
   
           nd6_cache_lladdr(ifp, &saddr6, lladdr,
               lladdrlen, ND_ROUTER_ADVERT, 0);
   
           /*
            * Installing a link-layer address might change the state of the
            * router's neighbor cache, which might also affect our on-link
            * detection of adveritsed prefixes.
            */
           pfxlist_onlink_check();
       }
   
    freeit:
           m_freem(m);
           return;
   
    bad:
           ICMP6STAT_INC(icp6s_badra);
           m_freem(m);
   }
   
   /* PFXRTR */
   static struct nd_pfxrouter *
   pfxrtr_lookup(struct nd_prefix *pr, struct nd_defrouter *dr)
   {
           struct nd_pfxrouter *search;
   
           ND6_LOCK_ASSERT();
   
           LIST_FOREACH(search, &pr->ndpr_advrtrs, pfr_entry) {
                   if (search->router == dr)
                           break;
           }
           return (search);
   }
   
   static void
   pfxrtr_add(struct nd_prefix *pr, struct nd_defrouter *dr)
   {
           struct nd_pfxrouter *new;
           bool update;
   
           ND6_UNLOCK_ASSERT();
   
           ND6_RLOCK();
           if (pfxrtr_lookup(pr, dr) != NULL) {
                   ND6_RUNLOCK();
                   return;
           }
           ND6_RUNLOCK();
   
           new = malloc(sizeof(*new), M_IP6NDP, M_NOWAIT | M_ZERO);
           if (new == NULL)
                   return;
           defrouter_ref(dr);
           new->router = dr;
   
           ND6_WLOCK();
           if (pfxrtr_lookup(pr, dr) == NULL) {
                   LIST_INSERT_HEAD(&pr->ndpr_advrtrs, new, pfr_entry);
                   update = true;
           } else {
                   /* We lost a race to add the reference. */
                   defrouter_rele(dr);
                   free(new, M_IP6NDP);
                   update = false;
           }
           ND6_WUNLOCK();
   
           if (update)
                   pfxlist_onlink_check();
   }
   
   static void
   pfxrtr_del(struct nd_pfxrouter *pfr)
   {
   
           ND6_WLOCK_ASSERT();
   
           LIST_REMOVE(pfr, pfr_entry);
           defrouter_rele(pfr->router);
           free(pfr, M_IP6NDP);
   }
   
   /* Default router list processing sub routines. */
   static void
   defrouter_addreq(struct nd_defrouter *new)
   {
           struct sockaddr_in6 def, mask, gate;
           struct rt_addrinfo info;
           struct rib_cmd_info rc;
           unsigned int fibnum;
           int error;
   
           bzero(&def, sizeof(def));
           bzero(&mask, sizeof(mask));
           bzero(&gate, sizeof(gate));
   
           def.sin6_len = mask.sin6_len = gate.sin6_len =
               sizeof(struct sockaddr_in6);
           def.sin6_family = gate.sin6_family = AF_INET6;
           gate.sin6_addr = new->rtaddr;
           fibnum = new->ifp->if_fib;
   
           bzero((caddr_t)&info, sizeof(info));
           info.rti_flags = RTF_GATEWAY;
           info.rti_info[RTAX_DST] = (struct sockaddr *)&def;
           info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&gate;
           info.rti_info[RTAX_NETMASK] = (struct sockaddr *)&mask;
   
           NET_EPOCH_ASSERT();
           error = rib_action(fibnum, RTM_ADD, &info, &rc);
           if (error == 0) {
                   struct nhop_object *nh = nhop_select_func(rc.rc_nh_new, 0);
                   rt_routemsg(RTM_ADD, rc.rc_rt, nh, fibnum);
                   new->installed = 1;
           }
   }
   
   /*
    * Remove the default route for a given router.
    * This is just a subroutine function for defrouter_select_fib(), and
    * should not be called from anywhere else.
    */
   static void
   defrouter_delreq(struct nd_defrouter *dr)
   {
           struct sockaddr_in6 def, mask, gate;
           struct rt_addrinfo info;
           struct rib_cmd_info rc;
           struct epoch_tracker et;
           unsigned int fibnum;
           int error;
   
           bzero(&def, sizeof(def));
           bzero(&mask, sizeof(mask));
           bzero(&gate, sizeof(gate));
   
           def.sin6_len = mask.sin6_len = gate.sin6_len =
               sizeof(struct sockaddr_in6);
           def.sin6_family = gate.sin6_family = AF_INET6;
           gate.sin6_addr = dr->rtaddr;
           fibnum = dr->ifp->if_fib;
   
           bzero((caddr_t)&info, sizeof(info));
           info.rti_flags = RTF_GATEWAY;
           info.rti_info[RTAX_DST] = (struct sockaddr *)&def;
           info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&gate;
           info.rti_info[RTAX_NETMASK] = (struct sockaddr *)&mask;
   
           NET_EPOCH_ENTER(et);
           error = rib_action(fibnum, RTM_DELETE, &info, &rc);
           if (error == 0) {
                   struct nhop_object *nh = nhop_select_func(rc.rc_nh_old, 0);
                   rt_routemsg(RTM_DELETE, rc.rc_rt, nh, fibnum);
           }
           NET_EPOCH_EXIT(et);
   
           dr->installed = 0;
   }
   
   static void
   defrouter_del(struct nd_defrouter *dr)
   {
           struct nd_defrouter *deldr = NULL;
           struct nd_prefix *pr;
           struct nd_pfxrouter *pfxrtr;
   
           ND6_UNLOCK_ASSERT();
   
           /*
            * Flush all the routing table entries that use the router
            * as a next hop.
            */
           if (ND_IFINFO(dr->ifp)->flags & ND6_IFF_ACCEPT_RTADV)
                   rt6_flush(&dr->rtaddr, dr->ifp);
   
   #ifdef EXPERIMENTAL
           defrtr_ipv6_only_ifp(dr->ifp);
   #endif
   
           if (dr->installed) {
                   deldr = dr;
                   defrouter_delreq(dr);
           }
   
           /*
            * Also delete all the pointers to the router in each prefix lists.
            */
           ND6_WLOCK();
           LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                   if ((pfxrtr = pfxrtr_lookup(pr, dr)) != NULL)
                           pfxrtr_del(pfxrtr);
           }
           ND6_WUNLOCK();
   
           pfxlist_onlink_check();
   
           /*
            * If the router is the primary one, choose a new one.
            * Note that defrouter_select_fib() will remove the current
            * gateway from the routing table.
            */
           if (deldr)
                   defrouter_select_fib(deldr->ifp->if_fib);
   
           /*
            * Release the list reference.
            */
           defrouter_rele(dr);
   }
   
   struct nd_defrouter *
   defrouter_lookup_locked(const struct in6_addr *addr, struct ifnet *ifp)
   {
           struct nd_defrouter *dr;
   
           ND6_LOCK_ASSERT();
           TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry)
                   if (dr->ifp == ifp && IN6_ARE_ADDR_EQUAL(addr, &dr->rtaddr)) {
                           defrouter_ref(dr);
                           return (dr);
                   }
           return (NULL);
   }
   
   struct nd_defrouter *
   defrouter_lookup(const struct in6_addr *addr, struct ifnet *ifp)
   {
           struct nd_defrouter *dr;
   
           ND6_RLOCK();
           dr = defrouter_lookup_locked(addr, ifp);
           ND6_RUNLOCK();
           return (dr);
   }
   
   /*
    * Remove all default routes from default router list.
    */
   void
   defrouter_reset(void)
   {
           struct nd_defrouter *dr, **dra;
           int count, i;
   
           count = i = 0;
   
           /*
            * We can't delete routes with the ND lock held, so make a copy of the
            * current default router list and use that when deleting routes.
            */
           ND6_RLOCK();
           TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry)
                   count++;
           ND6_RUNLOCK();
   
           dra = malloc(count * sizeof(*dra), M_TEMP, M_WAITOK | M_ZERO);
   
           ND6_RLOCK();
           TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry) {
                   if (i == count)
                           break;
                   defrouter_ref(dr);
                   dra[i++] = dr;
           }
           ND6_RUNLOCK();
   
           for (i = 0; i < count && dra[i] != NULL; i++) {
                   defrouter_delreq(dra[i]);
                   defrouter_rele(dra[i]);
           }
           free(dra, M_TEMP);
   
           /*
            * XXX should we also nuke any default routers in the kernel, by
            * going through them by rtalloc1()?
            */
   }
   
   /*
    * Look up a matching default router list entry and remove it. Returns true if a
    * matching entry was found, false otherwise.
    */
   bool
   defrouter_remove(struct in6_addr *addr, struct ifnet *ifp)
   {
           struct nd_defrouter *dr;
   
           ND6_WLOCK();
           dr = defrouter_lookup_locked(addr, ifp);
           if (dr == NULL) {
                   ND6_WUNLOCK();
                   return (false);
           }
   
           defrouter_unlink(dr, NULL);
           ND6_WUNLOCK();
           defrouter_del(dr);
           defrouter_rele(dr);
           return (true);
   }
   
   /*
    * for default router selection
    * regards router-preference field as a 2-bit signed integer
    */
   static int
   rtpref(struct nd_defrouter *dr)
   {
           switch (dr->raflags & ND_RA_FLAG_RTPREF_MASK) {
           case ND_RA_FLAG_RTPREF_HIGH:
                   return (RTPREF_HIGH);
           case ND_RA_FLAG_RTPREF_MEDIUM:
           case ND_RA_FLAG_RTPREF_RSV:
                   return (RTPREF_MEDIUM);
           case ND_RA_FLAG_RTPREF_LOW:
                   return (RTPREF_LOW);
           default:
                   /*
                    * This case should never happen.  If it did, it would mean a
                    * serious bug of kernel internal.  We thus always bark here.
                    * Or, can we even panic?
                    */
                   log(LOG_ERR, "rtpref: impossible RA flag %x\n", dr->raflags);
                   return (RTPREF_INVALID);
           }
           /* NOTREACHED */
   }
   
   static bool
   is_dr_reachable(const struct nd_defrouter *dr) {
           struct llentry *ln = NULL;
   
           ln = nd6_lookup(&dr->rtaddr, LLE_SF(AF_INET6, 0), dr->ifp);
           if (ln == NULL)
                   return (false);
           bool reachable = ND6_IS_LLINFO_PROBREACH(ln);
           LLE_RUNLOCK(ln);
           return reachable;
   }
   
   /*
    * Default Router Selection according to Section 6.3.6 of RFC 2461 and
    * draft-ietf-ipngwg-router-selection:
    * 1) Routers that are reachable or probably reachable should be preferred.
    *    If we have more than one (probably) reachable router, prefer ones
    *    with the highest router preference.
    * 2) When no routers on the list are known to be reachable or
    *    probably reachable, routers SHOULD be selected in a round-robin
    *    fashion, regardless of router preference values.
    * 3) If the Default Router List is empty, assume that all
    *    destinations are on-link.
    *
    * We assume nd_defrouter is sorted by router preference value.
    * Since the code below covers both with and without router preference cases,
    * we do not need to classify the cases by ifdef.
    *
    * At this moment, we do not try to install more than one default router,
    * even when the multipath routing is available, because we're not sure about
    * the benefits for stub hosts comparing to the risk of making the code
    * complicated and the possibility of introducing bugs.
    *
    * We maintain a single list of routers for multiple FIBs, only considering one
    * at a time based on the receiving interface's FIB. If @fibnum is RT_ALL_FIBS,
    * we do the whole thing multiple times.
    */
   void
   defrouter_select_fib(int fibnum)
   {
           struct epoch_tracker et;
           struct nd_defrouter *dr, *selected_dr, *installed_dr;
   
           if (fibnum == RT_ALL_FIBS) {
                   for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
                           defrouter_select_fib(fibnum);
                   }
                   return;
           }
   
           ND6_RLOCK();
           /*
            * Let's handle easy case (3) first:
            * If default router list is empty, there's nothing to be done.
            */
           if (TAILQ_EMPTY(&V_nd6_defrouter)) {
                   ND6_RUNLOCK();
                   return;
           }
   
           /*
            * Search for a (probably) reachable router from the list.
            * We just pick up the first reachable one (if any), assuming that
            * the ordering rule of the list described in defrtrlist_update().
            */
           selected_dr = installed_dr = NULL;
           NET_EPOCH_ENTER(et);
           TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry) {
                   if (dr->ifp->if_fib != fibnum)
                           continue;
   
                   if (selected_dr == NULL && is_dr_reachable(dr)) {
                           selected_dr = dr;
                           defrouter_ref(selected_dr);
                   }
   
                   if (dr->installed) {
                           if (installed_dr == NULL) {
                                   installed_dr = dr;
                                   defrouter_ref(installed_dr);
                           } else {
                                  /*
                                   * this should not happen.
                                   * warn for diagnosis.
                                   */
                                  log(LOG_ERR, "defrouter_select_fib: more than "
                                               "one router is installed\n");
                          }
                  }
          }
  
          /*
           * If none of the default routers was found to be reachable,
           * round-robin the list regardless of preference.
           * Otherwise, if we have an installed router, check if the selected
           * (reachable) router should really be preferred to the installed one.
           * We only prefer the new router when the old one is not reachable
           * or when the new one has a really higher preference value.
           */
          if (selected_dr == NULL) {
                  if (installed_dr == NULL ||
                      TAILQ_NEXT(installed_dr, dr_entry) == NULL)
                          dr = TAILQ_FIRST(&V_nd6_defrouter);
                  else
                          dr = TAILQ_NEXT(installed_dr, dr_entry);
  
                  /* Ensure we select a router for this FIB. */
                  TAILQ_FOREACH_FROM(dr, &V_nd6_defrouter, dr_entry) {
                          if (dr->ifp->if_fib == fibnum) {
                                  selected_dr = dr;
                                  defrouter_ref(selected_dr);
                                  break;
                          }
                  }
          } else if (installed_dr != NULL) {
                  if (is_dr_reachable(installed_dr) &&
                      rtpref(selected_dr) <= rtpref(installed_dr)) {
                          defrouter_rele(selected_dr);
                          selected_dr = installed_dr;
                  }
          }
          ND6_RUNLOCK();
  
          /*
           * If we selected a router for this FIB and it's different
           * than the installed one, remove the installed router and
           * install the selected one in its place.
           */
          if (installed_dr != selected_dr) {
                  if (installed_dr != NULL) {
                          defrouter_delreq(installed_dr);
                          defrouter_rele(installed_dr);
                  }
                  if (selected_dr != NULL)
                          defrouter_addreq(selected_dr);
          }
          if (selected_dr != NULL)
                  defrouter_rele(selected_dr);
          NET_EPOCH_EXIT(et);
  }
  
  static struct nd_defrouter *
  defrtrlist_update(struct nd_defrouter *new)
  {
          struct nd_defrouter *dr, *n;
          uint64_t genid;
          int oldpref;
          bool writelocked;
  
          if (new->rtlifetime == 0) {
                  defrouter_remove(&new->rtaddr, new->ifp);
                  return (NULL);
          }
  
          ND6_RLOCK();
          writelocked = false;
  restart:
          dr = defrouter_lookup_locked(&new->rtaddr, new->ifp);
          if (dr != NULL) {
                  oldpref = rtpref(dr);
  
                  /* override */
                  dr->raflags = new->raflags; /* XXX flag check */
                  dr->rtlifetime = new->rtlifetime;
                  dr->expire = new->expire;
  
                  /*
                   * If the preference does not change, there's no need
                   * to sort the entries. Also make sure the selected
                   * router is still installed in the kernel.
                   */
                  if (dr->installed && rtpref(new) == oldpref) {
                          if (writelocked)
                                  ND6_WUNLOCK();
                          else
                                  ND6_RUNLOCK();
                          return (dr);
                  }
          }
  
          /*
           * The router needs to be reinserted into the default router
           * list, so upgrade to a write lock. If that fails and the list
           * has potentially changed while the lock was dropped, we'll
           * redo the lookup with the write lock held.
           */
          if (!writelocked) {
                  writelocked = true;
                  if (!ND6_TRY_UPGRADE()) {
                          genid = V_nd6_list_genid;
                          ND6_RUNLOCK();
                          ND6_WLOCK();
                          if (genid != V_nd6_list_genid)
                                  goto restart;
                  }
          }
  
          if (dr != NULL) {
                  /*
                   * The preferred router may have changed, so relocate this
                   * router.
                   */
                  TAILQ_REMOVE(&V_nd6_defrouter, dr, dr_entry);
                  n = dr;
          } else {
                  n = malloc(sizeof(*n), M_IP6NDP, M_NOWAIT | M_ZERO);
                  if (n == NULL) {
                          ND6_WUNLOCK();
                          return (NULL);
                  }
                  memcpy(n, new, sizeof(*n));
                  /* Initialize with an extra reference for the caller. */
                  refcount_init(&n->refcnt, 2);
          }
  
          /*
           * Insert the new router in the Default Router List;
           * The Default Router List should be in the descending order
           * of router-preferece.  Routers with the same preference are
           * sorted in the arriving time order.
           */
  
          /* insert at the end of the group */
          TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry) {
                  if (rtpref(n) > rtpref(dr))
                          break;
          }
          if (dr != NULL)
                  TAILQ_INSERT_BEFORE(dr, n, dr_entry);
          else
                  TAILQ_INSERT_TAIL(&V_nd6_defrouter, n, dr_entry);
          V_nd6_list_genid++;
          ND6_WUNLOCK();
  
          defrouter_select_fib(new->ifp->if_fib);
  
          return (n);
  }
  
  static int
  in6_init_prefix_ltimes(struct nd_prefix *ndpr)
  {
          if (ndpr->ndpr_pltime == ND6_INFINITE_LIFETIME)
                  ndpr->ndpr_preferred = 0;
          else
                  ndpr->ndpr_preferred = time_uptime + ndpr->ndpr_pltime;
          if (ndpr->ndpr_vltime == ND6_INFINITE_LIFETIME)
                  ndpr->ndpr_expire = 0;
          else
                  ndpr->ndpr_expire = time_uptime + ndpr->ndpr_vltime;
  
          return 0;
  }
  
  static void
  in6_init_address_ltimes(struct nd_prefix *new, struct in6_addrlifetime *lt6)
  {
          /* init ia6t_expire */
          if (lt6->ia6t_vltime == ND6_INFINITE_LIFETIME)
                  lt6->ia6t_expire = 0;
          else {
                  lt6->ia6t_expire = time_uptime;
                  lt6->ia6t_expire += lt6->ia6t_vltime;
          }
  
          /* init ia6t_preferred */
          if (lt6->ia6t_pltime == ND6_INFINITE_LIFETIME)
                  lt6->ia6t_preferred = 0;
          else {
                  lt6->ia6t_preferred = time_uptime;
                  lt6->ia6t_preferred += lt6->ia6t_pltime;
          }
  }
  
  static struct in6_ifaddr *
  in6_ifadd(struct nd_prefixctl *pr, int mcast)
  {
          struct ifnet *ifp = pr->ndpr_ifp;
          struct ifaddr *ifa;
          struct in6_aliasreq ifra;
          struct in6_ifaddr *ia, *ib;
          int error, plen0;
          struct in6_addr mask;
          int prefixlen = pr->ndpr_plen;
          int updateflags;
          char ip6buf[INET6_ADDRSTRLEN];
  
          in6_prefixlen2mask(&mask, prefixlen);
  
          /*
           * find a link-local address (will be interface ID).
           * Is it really mandatory? Theoretically, a global or a site-local
           * address can be configured without a link-local address, if we
           * have a unique interface identifier...
           *
           * it is not mandatory to have a link-local address, we can generate
           * interface identifier on the fly.  we do this because:
           * (1) it should be the easiest way to find interface identifier.
           * (2) RFC2462 5.4 suggesting the use of the same interface identifier
           * for multiple addresses on a single interface, and possible shortcut
           * of DAD.  we omitted DAD for this reason in the past.
           * (3) a user can prevent autoconfiguration of global address
           * by removing link-local address by hand (this is partly because we
           * don't have other way to control the use of IPv6 on an interface.
           * this has been our design choice - cf. NRL's "ifconfig auto").
           * (4) it is easier to manage when an interface has addresses
           * with the same interface identifier, than to have multiple addresses
           * with different interface identifiers.
           */
          ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0); /* 0 is OK? */
          if (ifa)
                  ib = (struct in6_ifaddr *)ifa;
          else
                  return NULL;
  
          /* prefixlen + ifidlen must be equal to 128 */
          plen0 = in6_mask2len(&ib->ia_prefixmask.sin6_addr, NULL);
          if (prefixlen != plen0) {
                  ifa_free(ifa);
                  nd6log((LOG_INFO,
                      "%s: wrong prefixlen for %s (prefix=%d ifid=%d)\n",
                      __func__, if_name(ifp), prefixlen, 128 - plen0));
                  return NULL;
          }
  
          /* make ifaddr */
          in6_prepare_ifra(&ifra, &pr->ndpr_prefix.sin6_addr, &mask);
  
          IN6_MASK_ADDR(&ifra.ifra_addr.sin6_addr, &mask);
          /* interface ID */
          ifra.ifra_addr.sin6_addr.s6_addr32[0] |=
              (ib->ia_addr.sin6_addr.s6_addr32[0] & ~mask.s6_addr32[0]);
          ifra.ifra_addr.sin6_addr.s6_addr32[1] |=
              (ib->ia_addr.sin6_addr.s6_addr32[1] & ~mask.s6_addr32[1]);
          ifra.ifra_addr.sin6_addr.s6_addr32[2] |=
              (ib->ia_addr.sin6_addr.s6_addr32[2] & ~mask.s6_addr32[2]);
          ifra.ifra_addr.sin6_addr.s6_addr32[3] |=
              (ib->ia_addr.sin6_addr.s6_addr32[3] & ~mask.s6_addr32[3]);
          ifa_free(ifa);
  
          /* lifetimes. */
          ifra.ifra_lifetime.ia6t_vltime = pr->ndpr_vltime;
          ifra.ifra_lifetime.ia6t_pltime = pr->ndpr_pltime;
  
          /* XXX: scope zone ID? */
  
          ifra.ifra_flags |= IN6_IFF_AUTOCONF; /* obey autoconf */
  
          /*
           * Make sure that we do not have this address already.  This should
           * usually not happen, but we can still see this case, e.g., if we
           * have manually configured the exact address to be configured.
           */
          ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp,
              &ifra.ifra_addr.sin6_addr);
          if (ifa != NULL) {
                  ifa_free(ifa);
                  /* this should be rare enough to make an explicit log */
                  log(LOG_INFO, "in6_ifadd: %s is already configured\n",
                      ip6_sprintf(ip6buf, &ifra.ifra_addr.sin6_addr));
                  return (NULL);
          }
  
          /*
           * Allocate ifaddr structure, link into chain, etc.
           * If we are going to create a new address upon receiving a multicasted
           * RA, we need to impose a random delay before starting DAD.
           * [draft-ietf-ipv6-rfc2462bis-02.txt, Section 5.4.2]
           */
          updateflags = 0;
          if (mcast)
                  updateflags |= IN6_IFAUPDATE_DADDELAY;
          if ((error = in6_update_ifa(ifp, &ifra, NULL, updateflags)) != 0) {
                  nd6log((LOG_ERR,
                      "%s: failed to make ifaddr %s on %s (errno=%d)\n", __func__,
                      ip6_sprintf(ip6buf, &ifra.ifra_addr.sin6_addr),
                      if_name(ifp), error));
                  return (NULL);  /* ifaddr must not have been allocated. */
          }
  
          ia = in6ifa_ifpwithaddr(ifp, &ifra.ifra_addr.sin6_addr);
          /*
           * XXXRW: Assumption of non-NULLness here might not be true with
           * fine-grained locking -- should we validate it?  Or just return
           * earlier ifa rather than looking it up again?
           */
          return (ia);            /* this is always non-NULL  and referenced. */
  }
  
  static struct nd_prefix *
  nd6_prefix_lookup_locked(struct nd_prefixctl *key)
  {
          struct nd_prefix *search;
  
          ND6_LOCK_ASSERT();
  
          LIST_FOREACH(search, &V_nd_prefix, ndpr_entry) {
                  if (key->ndpr_ifp == search->ndpr_ifp &&
                      key->ndpr_plen == search->ndpr_plen &&
                      in6_are_prefix_equal(&key->ndpr_prefix.sin6_addr,
                      &search->ndpr_prefix.sin6_addr, key->ndpr_plen)) {
                          nd6_prefix_ref(search);
                          break;
                  }
          }
          return (search);
  }
  
  struct nd_prefix *
  nd6_prefix_lookup(struct nd_prefixctl *key)
  {
          struct nd_prefix *search;
  
          ND6_RLOCK();
          search = nd6_prefix_lookup_locked(key);
          ND6_RUNLOCK();
          return (search);
  }
  
  void
  nd6_prefix_ref(struct nd_prefix *pr)
  {
  
          refcount_acquire(&pr->ndpr_refcnt);
  }
  
  void
  nd6_prefix_rele(struct nd_prefix *pr)
  {
  
          if (refcount_release(&pr->ndpr_refcnt)) {
                  KASSERT(LIST_EMPTY(&pr->ndpr_advrtrs),
                      ("prefix %p has advertising routers", pr));
                  free(pr, M_IP6NDP);
          }
  }
  
  int
  nd6_prelist_add(struct nd_prefixctl *pr, struct nd_defrouter *dr,
      struct nd_prefix **newp)
  {
          struct nd_prefix *new;
          char ip6buf[INET6_ADDRSTRLEN];
          int error;
  
          new = malloc(sizeof(*new), M_IP6NDP, M_NOWAIT | M_ZERO);
          if (new == NULL)
                  return (ENOMEM);
          refcount_init(&new->ndpr_refcnt, newp != NULL ? 2 : 1);
          new->ndpr_ifp = pr->ndpr_ifp;
          new->ndpr_prefix = pr->ndpr_prefix;
          new->ndpr_plen = pr->ndpr_plen;
          new->ndpr_vltime = pr->ndpr_vltime;
          new->ndpr_pltime = pr->ndpr_pltime;
          new->ndpr_flags = pr->ndpr_flags;
          if ((error = in6_init_prefix_ltimes(new)) != 0) {
                  free(new, M_IP6NDP);
                  return (error);
          }
          new->ndpr_lastupdate = time_uptime;
  
          /* initialization */
          LIST_INIT(&new->ndpr_advrtrs);
          in6_prefixlen2mask(&new->ndpr_mask, new->ndpr_plen);
          /* make prefix in the canonical form */
          IN6_MASK_ADDR(&new->ndpr_prefix.sin6_addr, &new->ndpr_mask);
  
          ND6_WLOCK();
          LIST_INSERT_HEAD(&V_nd_prefix, new, ndpr_entry);
          V_nd6_list_genid++;
          ND6_WUNLOCK();
  
          /* ND_OPT_PI_FLAG_ONLINK processing */
          if (new->ndpr_raf_onlink) {
                  struct epoch_tracker et;
  
                  ND6_ONLINK_LOCK();
                  NET_EPOCH_ENTER(et);
                  if ((error = nd6_prefix_onlink(new)) != 0) {
                          nd6log((LOG_ERR, "%s: failed to make the prefix %s/%d "
                              "on-link on %s (errno=%d)\n", __func__,
                              ip6_sprintf(ip6buf, &pr->ndpr_prefix.sin6_addr),
                              pr->ndpr_plen, if_name(pr->ndpr_ifp), error));
                          /* proceed anyway. XXX: is it correct? */
                  }
                  NET_EPOCH_EXIT(et);
                  ND6_ONLINK_UNLOCK();
          }
  
          if (dr != NULL)
                  pfxrtr_add(new, dr);
          if (newp != NULL)
                  *newp = new;
          return (0);
  }
  
  /*
   * Remove a prefix from the prefix list and optionally stash it in a
   * caller-provided list.
   *
   * The ND6 lock must be held.
   */
  void
  nd6_prefix_unlink(struct nd_prefix *pr, struct nd_prhead *list)
  {
  
          ND6_WLOCK_ASSERT();
  
          LIST_REMOVE(pr, ndpr_entry);
          V_nd6_list_genid++;
          if (list != NULL)
                  LIST_INSERT_HEAD(list, pr, ndpr_entry);
  }
  
  /*
   * Free an unlinked prefix, first marking it off-link if necessary.
   */
  void
  nd6_prefix_del(struct nd_prefix *pr)
  {
          struct nd_pfxrouter *pfr, *next;
          int e;
          char ip6buf[INET6_ADDRSTRLEN];
  
          KASSERT(pr->ndpr_addrcnt == 0,
              ("prefix %p has referencing addresses", pr));
          ND6_UNLOCK_ASSERT();
  
          /*
           * Though these flags are now meaningless, we'd rather keep the value
           * of pr->ndpr_raf_onlink and pr->ndpr_raf_auto not to confuse users
           * when executing "ndp -p".
           */
          if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
                  ND6_ONLINK_LOCK();
                  if ((e = nd6_prefix_offlink(pr)) != 0) {
                          nd6log((LOG_ERR,
                              "%s: failed to make the prefix %s/%d offlink on %s "
                              "(errno=%d)\n", __func__,
                              ip6_sprintf(ip6buf, &pr->ndpr_prefix.sin6_addr),
                              pr->ndpr_plen, if_name(pr->ndpr_ifp), e));
                          /* what should we do? */
                  }
                  ND6_ONLINK_UNLOCK();
          }
  
          /* Release references to routers that have advertised this prefix. */
          ND6_WLOCK();
          LIST_FOREACH_SAFE(pfr, &pr->ndpr_advrtrs, pfr_entry, next)
                  pfxrtr_del(pfr);
          ND6_WUNLOCK();
  
          nd6_prefix_rele(pr);
  
          pfxlist_onlink_check();
  }
  
  static int
  prelist_update(struct nd_prefixctl *new, struct nd_defrouter *dr,
      struct mbuf *m, int mcast)
  {
          struct in6_ifaddr *ia6 = NULL, *ia6_match = NULL;
          struct ifaddr *ifa;
          struct ifnet *ifp = new->ndpr_ifp;
          struct nd_prefix *pr;
          int error = 0;
          int auth;
          struct in6_addrlifetime lt6_tmp;
          char ip6buf[INET6_ADDRSTRLEN];
  
          NET_EPOCH_ASSERT();
  
          auth = 0;
          if (m) {
                  /*
                   * Authenticity for NA consists authentication for
                   * both IP header and IP datagrams, doesn't it ?
                   */
  #if defined(M_AUTHIPHDR) && defined(M_AUTHIPDGM)
                  auth = ((m->m_flags & M_AUTHIPHDR) &&
                      (m->m_flags & M_AUTHIPDGM));
  #endif
          }
  
          if ((pr = nd6_prefix_lookup(new)) != NULL) {
                  /*
                   * nd6_prefix_lookup() ensures that pr and new have the same
                   * prefix on a same interface.
                   */
  
                  /*
                   * Update prefix information.  Note that the on-link (L) bit
                   * and the autonomous (A) bit should NOT be changed from 1
                   * to 0.
                   */
                  if (new->ndpr_raf_onlink == 1)
                          pr->ndpr_raf_onlink = 1;
                  if (new->ndpr_raf_auto == 1)
                          pr->ndpr_raf_auto = 1;
                  if (new->ndpr_raf_onlink) {
                          pr->ndpr_vltime = new->ndpr_vltime;
                          pr->ndpr_pltime = new->ndpr_pltime;
                          (void)in6_init_prefix_ltimes(pr); /* XXX error case? */
                          pr->ndpr_lastupdate = time_uptime;
                  }
  
                  if (new->ndpr_raf_onlink &&
                      (pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
                          ND6_ONLINK_LOCK();
                          if ((error = nd6_prefix_onlink(pr)) != 0) {
                                  nd6log((LOG_ERR,
                                      "%s: failed to make the prefix %s/%d "
                                      "on-link on %s (errno=%d)\n", __func__,
                                      ip6_sprintf(ip6buf,
                                          &pr->ndpr_prefix.sin6_addr),
                                      pr->ndpr_plen, if_name(pr->ndpr_ifp),
                                      error));
                                  /* proceed anyway. XXX: is it correct? */
                          }
                          ND6_ONLINK_UNLOCK();
                  }
  
                  if (dr != NULL)
                          pfxrtr_add(pr, dr);
          } else {
                  if (new->ndpr_vltime == 0)
                          goto end;
                  if (new->ndpr_raf_onlink == 0 && new->ndpr_raf_auto == 0)
                          goto end;
  
                  error = nd6_prelist_add(new, dr, &pr);
                  if (error != 0) {
                          nd6log((LOG_NOTICE, "%s: nd6_prelist_add() failed for "
                              "the prefix %s/%d on %s (errno=%d)\n", __func__,
                              ip6_sprintf(ip6buf, &new->ndpr_prefix.sin6_addr),
                              new->ndpr_plen, if_name(new->ndpr_ifp), error));
                          goto end; /* we should just give up in this case. */
                  }
  
                  /*
                   * XXX: from the ND point of view, we can ignore a prefix
                   * with the on-link bit being zero.  However, we need a
                   * prefix structure for references from autoconfigured
                   * addresses.  Thus, we explicitly make sure that the prefix
                   * itself expires now.
                   */
                  if (pr->ndpr_raf_onlink == 0) {
                          pr->ndpr_vltime = 0;
                          pr->ndpr_pltime = 0;
                          in6_init_prefix_ltimes(pr);
                  }
          }
  
          /*
           * Address autoconfiguration based on Section 5.5.3 of RFC 2462.
           * Note that pr must be non NULL at this point.
           */
  
          /* 5.5.3 (a). Ignore the prefix without the A bit set. */
          if (!new->ndpr_raf_auto)
                  goto end;
  
          /*
           * 5.5.3 (b). the link-local prefix should have been ignored in
           * nd6_ra_input.
           */
  
          /* 5.5.3 (c). Consistency check on lifetimes: pltime <= vltime. */
          if (new->ndpr_pltime > new->ndpr_vltime) {
                  error = EINVAL; /* XXX: won't be used */
                  goto end;
          }
  
          /*
           * 5.5.3 (d).  If the prefix advertised is not equal to the prefix of
           * an address configured by stateless autoconfiguration already in the
           * list of addresses associated with the interface, and the Valid
           * Lifetime is not 0, form an address.  We first check if we have
           * a matching prefix.
           * Note: we apply a clarification in rfc2462bis-02 here.  We only
           * consider autoconfigured addresses while RFC2462 simply said
           * "address".
           */
          CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  struct in6_ifaddr *ifa6;
                  u_int32_t remaininglifetime;
  
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
  
                  ifa6 = (struct in6_ifaddr *)ifa;
  
                  /*
                   * We only consider autoconfigured addresses as per rfc2462bis.
                   */
                  if (!(ifa6->ia6_flags & IN6_IFF_AUTOCONF))
                          continue;
  
                  /*
                   * Spec is not clear here, but I believe we should concentrate
                   * on unicast (i.e. not anycast) addresses.
                   * XXX: other ia6_flags? detached or duplicated?
                   */
                  if ((ifa6->ia6_flags & IN6_IFF_ANYCAST) != 0)
                          continue;
  
                  /*
                   * Ignore the address if it is not associated with a prefix
                   * or is associated with a prefix that is different from this
                   * one.  (pr is never NULL here)
                   */
                  if (ifa6->ia6_ndpr != pr)
                          continue;
  
                  if (ia6_match == NULL) /* remember the first one */
                          ia6_match = ifa6;
  
                  /*
                   * An already autoconfigured address matched.  Now that we
                   * are sure there is at least one matched address, we can
                   * proceed to 5.5.3. (e): update the lifetimes according to the
                   * "two hours" rule and the privacy extension.
                   * We apply some clarifications in rfc2462bis:
                   * - use remaininglifetime instead of storedlifetime as a
                   *   variable name
                   * - remove the dead code in the "two-hour" rule
                   */
  #define TWOHOUR         (120*60)
                  lt6_tmp = ifa6->ia6_lifetime;
  
                  if (lt6_tmp.ia6t_vltime == ND6_INFINITE_LIFETIME)
                          remaininglifetime = ND6_INFINITE_LIFETIME;
                  else if (time_uptime - ifa6->ia6_updatetime >
                           lt6_tmp.ia6t_vltime) {
                          /*
                           * The case of "invalid" address.  We should usually
                           * not see this case.
                           */
                          remaininglifetime = 0;
                  } else
                          remaininglifetime = lt6_tmp.ia6t_vltime -
                              (time_uptime - ifa6->ia6_updatetime);
  
                  /* when not updating, keep the current stored lifetime. */
                  lt6_tmp.ia6t_vltime = remaininglifetime;
  
                  if (TWOHOUR < new->ndpr_vltime ||
                      remaininglifetime < new->ndpr_vltime) {
                          lt6_tmp.ia6t_vltime = new->ndpr_vltime;
                  } else if (remaininglifetime <= TWOHOUR) {
                          if (auth) {
                                  lt6_tmp.ia6t_vltime = new->ndpr_vltime;
                          }
                  } else {
                          /*
                           * new->ndpr_vltime <= TWOHOUR &&
                           * TWOHOUR < remaininglifetime
                           */
                          lt6_tmp.ia6t_vltime = TWOHOUR;
                  }
  
                  /* The 2 hour rule is not imposed for preferred lifetime. */
                  lt6_tmp.ia6t_pltime = new->ndpr_pltime;
  
                  in6_init_address_ltimes(pr, &lt6_tmp);
  
                  /*
                   * We need to treat lifetimes for temporary addresses
                   * differently, according to
                   * draft-ietf-ipv6-privacy-addrs-v2-01.txt 3.3 (1);
                   * we only update the lifetimes when they are in the maximum
                   * intervals.
                   */
                  if ((ifa6->ia6_flags & IN6_IFF_TEMPORARY) != 0) {
                          u_int32_t maxvltime, maxpltime;
  
                          if (V_ip6_temp_valid_lifetime >
                              (u_int32_t)((time_uptime - ifa6->ia6_createtime) +
                              V_ip6_desync_factor)) {
                                  maxvltime = V_ip6_temp_valid_lifetime -
                                      (time_uptime - ifa6->ia6_createtime) -
                                      V_ip6_desync_factor;
                          } else
                                  maxvltime = 0;
                          if (V_ip6_temp_preferred_lifetime >
                              (u_int32_t)((time_uptime - ifa6->ia6_createtime) +
                              V_ip6_desync_factor)) {
                                  maxpltime = V_ip6_temp_preferred_lifetime -
                                      (time_uptime - ifa6->ia6_createtime) -
                                      V_ip6_desync_factor;
                          } else
                                  maxpltime = 0;
  
                          if (lt6_tmp.ia6t_vltime == ND6_INFINITE_LIFETIME ||
                              lt6_tmp.ia6t_vltime > maxvltime) {
                                  lt6_tmp.ia6t_vltime = maxvltime;
                          }
                          if (lt6_tmp.ia6t_pltime == ND6_INFINITE_LIFETIME ||
                              lt6_tmp.ia6t_pltime > maxpltime) {
                                  lt6_tmp.ia6t_pltime = maxpltime;
                          }
                  }
                  ifa6->ia6_lifetime = lt6_tmp;
                  ifa6->ia6_updatetime = time_uptime;
          }
          if (ia6_match == NULL && new->ndpr_vltime) {
                  int ifidlen;
  
                  /*
                   * 5.5.3 (d) (continued)
                   * No address matched and the valid lifetime is non-zero.
                   * Create a new address.
                   */
  
                  /*
                   * Prefix Length check:
                   * If the sum of the prefix length and interface identifier
                   * length does not equal 128 bits, the Prefix Information
                   * option MUST be ignored.  The length of the interface
                   * identifier is defined in a separate link-type specific
                   * document.
                   */
                  ifidlen = in6_if2idlen(ifp);
                  if (ifidlen < 0) {
                          /* this should not happen, so we always log it. */
                          log(LOG_ERR, "prelist_update: IFID undefined (%s)\n",
                              if_name(ifp));
                          goto end;
                  }
                  if (ifidlen + pr->ndpr_plen != 128) {
                          nd6log((LOG_INFO,
                              "%s: invalid prefixlen %d for %s, ignored\n",
                              __func__, pr->ndpr_plen, if_name(ifp)));
                          goto end;
                  }
  
                  if ((ia6 = in6_ifadd(new, mcast)) != NULL) {
                          /*
                           * note that we should use pr (not new) for reference.
                           */
                          pr->ndpr_addrcnt++;
                          ia6->ia6_ndpr = pr;
  
                          /*
                           * RFC 3041 3.3 (2).
                           * When a new public address is created as described
                           * in RFC2462, also create a new temporary address.
                           *
                           * RFC 3041 3.5.
                           * When an interface connects to a new link, a new
                           * randomized interface identifier should be generated
                           * immediately together with a new set of temporary
                           * addresses.  Thus, we specifiy 1 as the 2nd arg of
                           * in6_tmpifadd().
                           */
                          if (V_ip6_use_tempaddr) {
                                  int e;
                                  if ((e = in6_tmpifadd(ia6, 1, 1)) != 0) {
                                          nd6log((LOG_NOTICE, "%s: failed to "
                                              "create a temporary address "
                                              "(errno=%d)\n", __func__, e));
                                  }
                          }
                          ifa_free(&ia6->ia_ifa);
  
                          /*
                           * A newly added address might affect the status
                           * of other addresses, so we check and update it.
                           * XXX: what if address duplication happens?
                           */
                          pfxlist_onlink_check();
                  } else {
                          /* just set an error. do not bark here. */
                          error = EADDRNOTAVAIL; /* XXX: might be unused. */
                  }
          }
  
  end:
          if (pr != NULL)
                  nd6_prefix_rele(pr);
          return (error);
  }
  
  /*
   * A supplement function used in the on-link detection below;
   * detect if a given prefix has a (probably) reachable advertising router.
   * XXX: lengthy function name...
   */
  static struct nd_pfxrouter *
  find_pfxlist_reachable_router(struct nd_prefix *pr)
  {
          struct epoch_tracker et;
          struct nd_pfxrouter *pfxrtr;
  
          ND6_LOCK_ASSERT();
  
          NET_EPOCH_ENTER(et);
          LIST_FOREACH(pfxrtr, &pr->ndpr_advrtrs, pfr_entry) {
                  if (is_dr_reachable(pfxrtr->router))
                          break;
          }
          NET_EPOCH_EXIT(et);
          return (pfxrtr);
  }
  
  /*
   * Check if each prefix in the prefix list has at least one available router
   * that advertised the prefix (a router is "available" if its neighbor cache
   * entry is reachable or probably reachable).
   * If the check fails, the prefix may be off-link, because, for example,
   * we have moved from the network but the lifetime of the prefix has not
   * expired yet.  So we should not use the prefix if there is another prefix
   * that has an available router.
   * But, if there is no prefix that has an available router, we still regard
   * all the prefixes as on-link.  This is because we can't tell if all the
   * routers are simply dead or if we really moved from the network and there
   * is no router around us.
   */
  void
  pfxlist_onlink_check(void)
  {
          struct nd_prefix *pr;
          struct in6_ifaddr *ifa;
          struct nd_defrouter *dr;
          struct nd_pfxrouter *pfxrtr = NULL;
          struct rm_priotracker in6_ifa_tracker;
          uint64_t genid;
          uint32_t flags;
  
          ND6_ONLINK_LOCK();
          ND6_RLOCK();
  
          /*
           * Check if there is a prefix that has a reachable advertising
           * router.
           */
          LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                  if (pr->ndpr_raf_onlink && find_pfxlist_reachable_router(pr))
                          break;
          }
  
          /*
           * If we have no such prefix, check whether we still have a router
           * that does not advertise any prefixes.
           */
          if (pr == NULL) {
                  TAILQ_FOREACH(dr, &V_nd6_defrouter, dr_entry) {
                          struct nd_prefix *pr0;
  
                          LIST_FOREACH(pr0, &V_nd_prefix, ndpr_entry) {
                                  if ((pfxrtr = pfxrtr_lookup(pr0, dr)) != NULL)
                                          break;
                          }
                          if (pfxrtr != NULL)
                                  break;
                  }
          }
          if (pr != NULL || (!TAILQ_EMPTY(&V_nd6_defrouter) && pfxrtr == NULL)) {
                  /*
                   * There is at least one prefix that has a reachable router,
                   * or at least a router which probably does not advertise
                   * any prefixes.  The latter would be the case when we move
                   * to a new link where we have a router that does not provide
                   * prefixes and we configure an address by hand.
                   * Detach prefixes which have no reachable advertising
                   * router, and attach other prefixes.
                   */
                  LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                          /* XXX: a link-local prefix should never be detached */
                          if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
                              pr->ndpr_raf_onlink == 0 ||
                              pr->ndpr_raf_auto == 0)
                                  continue;
  
                          if ((pr->ndpr_stateflags & NDPRF_DETACHED) == 0 &&
                              find_pfxlist_reachable_router(pr) == NULL)
                                  pr->ndpr_stateflags |= NDPRF_DETACHED;
                          else if ((pr->ndpr_stateflags & NDPRF_DETACHED) != 0 &&
                              find_pfxlist_reachable_router(pr) != NULL)
                                  pr->ndpr_stateflags &= ~NDPRF_DETACHED;
                  }
          } else {
                  /* there is no prefix that has a reachable router */
                  LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                          if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
                              pr->ndpr_raf_onlink == 0 ||
                              pr->ndpr_raf_auto == 0)
                                  continue;
                          pr->ndpr_stateflags &= ~NDPRF_DETACHED;
                  }
          }
  
          /*
           * Remove each interface route associated with a (just) detached
           * prefix, and reinstall the interface route for a (just) attached
           * prefix.  Note that all attempt of reinstallation does not
           * necessarily success, when a same prefix is shared among multiple
           * interfaces.  Such cases will be handled in nd6_prefix_onlink,
           * so we don't have to care about them.
           */
  restart:
          LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                  char ip6buf[INET6_ADDRSTRLEN];
                  int e;
  
                  if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
                      pr->ndpr_raf_onlink == 0 ||
                      pr->ndpr_raf_auto == 0)
                          continue;
  
                  flags = pr->ndpr_stateflags & (NDPRF_DETACHED | NDPRF_ONLINK);
                  if (flags == 0 || flags == (NDPRF_DETACHED | NDPRF_ONLINK)) {
                          genid = V_nd6_list_genid;
                          ND6_RUNLOCK();
                          if ((flags & NDPRF_ONLINK) != 0 &&
                              (e = nd6_prefix_offlink(pr)) != 0) {
                                  nd6log((LOG_ERR,
                                      "%s: failed to make %s/%d offlink "
                                      "(errno=%d)\n", __func__, 
                                      ip6_sprintf(ip6buf,
                                              &pr->ndpr_prefix.sin6_addr),
                                              pr->ndpr_plen, e));
                          } else if ((flags & NDPRF_ONLINK) == 0 &&
                              (e = nd6_prefix_onlink(pr)) != 0) {
                                  nd6log((LOG_ERR,
                                      "%s: failed to make %s/%d onlink "
                                      "(errno=%d)\n", __func__,
                                      ip6_sprintf(ip6buf,
                                              &pr->ndpr_prefix.sin6_addr),
                                              pr->ndpr_plen, e));
                          }
                          ND6_RLOCK();
                          if (genid != V_nd6_list_genid)
                                  goto restart;
                  }
          }
  
          /*
           * Changes on the prefix status might affect address status as well.
           * Make sure that all addresses derived from an attached prefix are
           * attached, and that all addresses derived from a detached prefix are
           * detached.  Note, however, that a manually configured address should
           * always be attached.
           * The precise detection logic is same as the one for prefixes.
           */
          IN6_IFADDR_RLOCK(&in6_ifa_tracker);
          CK_STAILQ_FOREACH(ifa, &V_in6_ifaddrhead, ia_link) {
                  if (!(ifa->ia6_flags & IN6_IFF_AUTOCONF))
                          continue;
  
                  if (ifa->ia6_ndpr == NULL) {
                          /*
                           * This can happen when we first configure the address
                           * (i.e. the address exists, but the prefix does not).
                           * XXX: complicated relationships...
                           */
                          continue;
                  }
  
                  if (find_pfxlist_reachable_router(ifa->ia6_ndpr))
                          break;
          }
          if (ifa) {
                  CK_STAILQ_FOREACH(ifa, &V_in6_ifaddrhead, ia_link) {
                          if ((ifa->ia6_flags & IN6_IFF_AUTOCONF) == 0)
                                  continue;
  
                          if (ifa->ia6_ndpr == NULL) /* XXX: see above. */
                                  continue;
  
                          if (find_pfxlist_reachable_router(ifa->ia6_ndpr)) {
                                  if (ifa->ia6_flags & IN6_IFF_DETACHED) {
                                          ifa->ia6_flags &= ~IN6_IFF_DETACHED;
                                          ifa->ia6_flags |= IN6_IFF_TENTATIVE;
                                          nd6_dad_start((struct ifaddr *)ifa, 0);
                                  }
                          } else {
                                  ifa->ia6_flags |= IN6_IFF_DETACHED;
                          }
                  }
          } else {
                  CK_STAILQ_FOREACH(ifa, &V_in6_ifaddrhead, ia_link) {
                          if ((ifa->ia6_flags & IN6_IFF_AUTOCONF) == 0)
                                  continue;
  
                          if (ifa->ia6_flags & IN6_IFF_DETACHED) {
                                  ifa->ia6_flags &= ~IN6_IFF_DETACHED;
                                  ifa->ia6_flags |= IN6_IFF_TENTATIVE;
                                  /* Do we need a delay in this case? */
                                  nd6_dad_start((struct ifaddr *)ifa, 0);
                          }
                  }
          }
          IN6_IFADDR_RUNLOCK(&in6_ifa_tracker);
          ND6_RUNLOCK();
          ND6_ONLINK_UNLOCK();
  }
  
  /*
   * Add or remove interface route specified by @dst, @netmask and @ifp.
   * ifa can be NULL.
   * Returns 0 on success
   */
  static int
  nd6_prefix_rtrequest(uint32_t fibnum, int cmd, struct sockaddr_in6 *dst,
      struct sockaddr_in6 *netmask, struct ifnet *ifp, struct ifaddr *ifa)
  {
          struct epoch_tracker et;
          int error;
  
          /* Prepare gateway */
          struct sockaddr_dl_short sdl = {
                  .sdl_family = AF_LINK,
                  .sdl_len = sizeof(struct sockaddr_dl_short),
                  .sdl_type = ifp->if_type,
                  .sdl_index = ifp->if_index,
          };
  
          struct rt_addrinfo info = {
                  .rti_ifa = ifa,
                  .rti_ifp = ifp,
                  .rti_flags = RTF_PINNED | ((netmask != NULL) ? 0 : RTF_HOST),
                  .rti_info = {
                          [RTAX_DST] = (struct sockaddr *)dst,
                          [RTAX_NETMASK] = (struct sockaddr *)netmask,
                          [RTAX_GATEWAY] = (struct sockaddr *)&sdl,
                  },
          };
          /* Don't set additional per-gw filters on removal */
  
          NET_EPOCH_ENTER(et);
          error = rib_handle_ifaddr_info(fibnum, cmd, &info);
          NET_EPOCH_EXIT(et);
          return (error);
  }
  
  static int
  nd6_prefix_onlink_rtrequest(struct nd_prefix *pr, struct ifaddr *ifa)
  {
          int error;
  
          struct sockaddr_in6 mask6 = {
                  .sin6_family = AF_INET6,
                  .sin6_len = sizeof(struct sockaddr_in6),
                  .sin6_addr = pr->ndpr_mask,
          };
          struct sockaddr_in6 *pmask6 = (pr->ndpr_plen != 128) ? &mask6 : NULL;
  
          error = nd6_prefix_rtrequest(pr->ndpr_ifp->if_fib, RTM_ADD,
              &pr->ndpr_prefix, pmask6, pr->ndpr_ifp, ifa);
          if (error == 0)
                  pr->ndpr_stateflags |= NDPRF_ONLINK;
  
          return (error);
  }
  
  static int
  nd6_prefix_onlink(struct nd_prefix *pr)
  {
          struct epoch_tracker et;
          struct ifaddr *ifa;
          struct ifnet *ifp = pr->ndpr_ifp;
          struct nd_prefix *opr;
          char ip6buf[INET6_ADDRSTRLEN];
          int error;
  
          ND6_ONLINK_LOCK_ASSERT();
          ND6_UNLOCK_ASSERT();
  
          if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0)
                  return (EEXIST);
  
          /*
           * Add the interface route associated with the prefix.  Before
           * installing the route, check if there's the same prefix on another
           * interface, and the prefix has already installed the interface route.
           * Although such a configuration is expected to be rare, we explicitly
           * allow it.
           */
          ND6_RLOCK();
          LIST_FOREACH(opr, &V_nd_prefix, ndpr_entry) {
                  if (opr == pr)
                          continue;
  
                  if ((opr->ndpr_stateflags & NDPRF_ONLINK) == 0)
                          continue;
  
                  if (!V_rt_add_addr_allfibs &&
                      opr->ndpr_ifp->if_fib != pr->ndpr_ifp->if_fib)
                          continue;
  
                  if (opr->ndpr_plen == pr->ndpr_plen &&
                      in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
                      &opr->ndpr_prefix.sin6_addr, pr->ndpr_plen)) {
                          ND6_RUNLOCK();
                          return (0);
                  }
          }
          ND6_RUNLOCK();
  
          /*
           * We prefer link-local addresses as the associated interface address.
           */
          /* search for a link-local addr */
          NET_EPOCH_ENTER(et);
          ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp,
              IN6_IFF_NOTREADY | IN6_IFF_ANYCAST);
          if (ifa == NULL) {
                  /* XXX: freebsd does not have ifa_ifwithaf */
                  CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family == AF_INET6) {
                                  ifa_ref(ifa);
                                  break;
                          }
                  }
                  /* should we care about ia6_flags? */
          }
          if (ifa == NULL) {
                  /*
                   * This can still happen, when, for example, we receive an RA
                   * containing a prefix with the L bit set and the A bit clear,
                   * after removing all IPv6 addresses on the receiving
                   * interface.  This should, of course, be rare though.
                   */
                  nd6log((LOG_NOTICE,
                      "%s: failed to find any ifaddr to add route for a "
                      "prefix(%s/%d) on %s\n", __func__,
                      ip6_sprintf(ip6buf, &pr->ndpr_prefix.sin6_addr),
                      pr->ndpr_plen, if_name(ifp)));
                  error = 0;
          } else {
                  error = nd6_prefix_onlink_rtrequest(pr, ifa);
                  ifa_free(ifa);
          }
          NET_EPOCH_EXIT(et);
  
          return (error);
  }
  
  int
  nd6_prefix_offlink(struct nd_prefix *pr)
  {
          int error = 0;
          struct ifnet *ifp = pr->ndpr_ifp;
          struct nd_prefix *opr;
          char ip6buf[INET6_ADDRSTRLEN];
          uint64_t genid;
          int a_failure;
  
          ND6_ONLINK_LOCK_ASSERT();
          ND6_UNLOCK_ASSERT();
  
          if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0)
                  return (EEXIST);
  
          struct sockaddr_in6 mask6 = {
                  .sin6_family = AF_INET6,
                  .sin6_len = sizeof(struct sockaddr_in6),
                  .sin6_addr = pr->ndpr_mask,
          };
          struct sockaddr_in6 *pmask6 = (pr->ndpr_plen != 128) ? &mask6 : NULL;
  
          error = nd6_prefix_rtrequest(ifp->if_fib, RTM_DELETE,
              &pr->ndpr_prefix, pmask6, ifp, NULL);
  
          a_failure = 1;
          if (error == 0) {
                  pr->ndpr_stateflags &= ~NDPRF_ONLINK;
  
                  /*
                   * There might be the same prefix on another interface,
                   * the prefix which could not be on-link just because we have
                   * the interface route (see comments in nd6_prefix_onlink).
                   * If there's one, try to make the prefix on-link on the
                   * interface.
                   */
                  ND6_RLOCK();
  restart:
                  LIST_FOREACH(opr, &V_nd_prefix, ndpr_entry) {
                          /*
                           * KAME specific: detached prefixes should not be
                           * on-link.
                           */
                          if (opr == pr || (opr->ndpr_stateflags &
                              (NDPRF_ONLINK | NDPRF_DETACHED)) != 0)
                                  continue;
  
                          if (opr->ndpr_plen == pr->ndpr_plen &&
                              in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
                              &opr->ndpr_prefix.sin6_addr, pr->ndpr_plen)) {
                                  int e;
  
                                  genid = V_nd6_list_genid;
                                  ND6_RUNLOCK();
                                  if ((e = nd6_prefix_onlink(opr)) != 0) {
                                          nd6log((LOG_ERR,
                                              "%s: failed to recover a prefix "
                                              "%s/%d from %s to %s (errno=%d)\n",
                                              __func__, ip6_sprintf(ip6buf,
                                                  &opr->ndpr_prefix.sin6_addr),
                                              opr->ndpr_plen, if_name(ifp),
                                              if_name(opr->ndpr_ifp), e));
                                  } else
                                          a_failure = 0;
                                  ND6_RLOCK();
                                  if (genid != V_nd6_list_genid)
                                          goto restart;
                          }
                  }
                  ND6_RUNLOCK();
          } else {
                  /* XXX: can we still set the NDPRF_ONLINK flag? */
                  nd6log((LOG_ERR,
                      "%s: failed to delete route: %s/%d on %s (errno=%d)\n",
                      __func__, ip6_sprintf(ip6buf, &pr->ndpr_prefix.sin6_addr),
                      pr->ndpr_plen, if_name(ifp), error));
          }
  
          if (a_failure)
                  lltable_prefix_free(AF_INET6,
                      (struct sockaddr *)&pr->ndpr_prefix,
                      (struct sockaddr *)&mask6, LLE_STATIC);
  
          return (error);
  }
  
  /*
   * ia0 - corresponding public address
   */
  int
  in6_tmpifadd(const struct in6_ifaddr *ia0, int forcegen, int delay)
  {
          struct ifnet *ifp = ia0->ia_ifa.ifa_ifp;
          struct in6_ifaddr *newia;
          struct in6_aliasreq ifra;
          int error;
          int trylimit = 3;       /* XXX: adhoc value */
          int updateflags;
          u_int32_t randid[2];
          time_t vltime0, pltime0;
  
          in6_prepare_ifra(&ifra, &ia0->ia_addr.sin6_addr,
              &ia0->ia_prefixmask.sin6_addr);
  
          ifra.ifra_addr = ia0->ia_addr;  /* XXX: do we need this ? */
          /* clear the old IFID */
          IN6_MASK_ADDR(&ifra.ifra_addr.sin6_addr,
              &ifra.ifra_prefixmask.sin6_addr);
  
    again:
          if (in6_get_tmpifid(ifp, (u_int8_t *)randid,
              (const u_int8_t *)&ia0->ia_addr.sin6_addr.s6_addr[8], forcegen)) {
                  nd6log((LOG_NOTICE, "%s: failed to find a good random IFID\n",
                      __func__));
                  return (EINVAL);
          }
          ifra.ifra_addr.sin6_addr.s6_addr32[2] |=
              (randid[0] & ~(ifra.ifra_prefixmask.sin6_addr.s6_addr32[2]));
          ifra.ifra_addr.sin6_addr.s6_addr32[3] |=
              (randid[1] & ~(ifra.ifra_prefixmask.sin6_addr.s6_addr32[3]));
  
          /*
           * in6_get_tmpifid() quite likely provided a unique interface ID.
           * However, we may still have a chance to see collision, because
           * there may be a time lag between generation of the ID and generation
           * of the address.  So, we'll do one more sanity check.
           */
  
          if (in6_localip(&ifra.ifra_addr.sin6_addr) != 0) {
                  if (trylimit-- > 0) {
                          forcegen = 1;
                          goto again;
                  }
  
                  /* Give up.  Something strange should have happened.  */
                  nd6log((LOG_NOTICE, "%s: failed to find a unique random IFID\n",
                      __func__));
                  return (EEXIST);
          }
  
          /*
           * The Valid Lifetime is the lower of the Valid Lifetime of the
           * public address or TEMP_VALID_LIFETIME.
           * The Preferred Lifetime is the lower of the Preferred Lifetime
           * of the public address or TEMP_PREFERRED_LIFETIME -
           * DESYNC_FACTOR.
           */
          if (ia0->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                  vltime0 = IFA6_IS_INVALID(ia0) ? 0 :
                      (ia0->ia6_lifetime.ia6t_vltime -
                      (time_uptime - ia0->ia6_updatetime));
                  if (vltime0 > V_ip6_temp_valid_lifetime)
                          vltime0 = V_ip6_temp_valid_lifetime;
          } else
                  vltime0 = V_ip6_temp_valid_lifetime;
          if (ia0->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                  pltime0 = IFA6_IS_DEPRECATED(ia0) ? 0 :
                      (ia0->ia6_lifetime.ia6t_pltime -
                      (time_uptime - ia0->ia6_updatetime));
                  if (pltime0 > V_ip6_temp_preferred_lifetime - V_ip6_desync_factor){
                          pltime0 = V_ip6_temp_preferred_lifetime -
                              V_ip6_desync_factor;
                  }
          } else
                  pltime0 = V_ip6_temp_preferred_lifetime - V_ip6_desync_factor;
          ifra.ifra_lifetime.ia6t_vltime = vltime0;
          ifra.ifra_lifetime.ia6t_pltime = pltime0;
  
          /*
           * A temporary address is created only if this calculated Preferred
           * Lifetime is greater than REGEN_ADVANCE time units.
           */
          if (ifra.ifra_lifetime.ia6t_pltime <= V_ip6_temp_regen_advance)
                  return (0);
  
          /* XXX: scope zone ID? */
  
          ifra.ifra_flags |= (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY);
  
          /* allocate ifaddr structure, link into chain, etc. */
          updateflags = 0;
          if (delay)
                  updateflags |= IN6_IFAUPDATE_DADDELAY;
          if ((error = in6_update_ifa(ifp, &ifra, NULL, updateflags)) != 0)
                  return (error);
  
          newia = in6ifa_ifpwithaddr(ifp, &ifra.ifra_addr.sin6_addr);
          if (newia == NULL) {    /* XXX: can it happen? */
                  nd6log((LOG_ERR,
                      "%s: ifa update succeeded, but we got no ifaddr\n",
                      __func__));
                  return (EINVAL); /* XXX */
          }
          newia->ia6_ndpr = ia0->ia6_ndpr;
          newia->ia6_ndpr->ndpr_addrcnt++;
          ifa_free(&newia->ia_ifa);
  
          /*
           * A newly added address might affect the status of other addresses.
           * XXX: when the temporary address is generated with a new public
           * address, the onlink check is redundant.  However, it would be safe
           * to do the check explicitly everywhere a new address is generated,
           * and, in fact, we surely need the check when we create a new
           * temporary address due to deprecation of an old temporary address.
           */
          pfxlist_onlink_check();
  
          return (0);
  }
  
  static int
  rt6_deleteroute(const struct rtentry *rt, const struct nhop_object *nh,
      void *arg)
  {
          struct in6_addr *gate = (struct in6_addr *)arg;
          int nh_rt_flags;
  
          if (nh->gw_sa.sa_family != AF_INET6)
                  return (0);
  
          if (!IN6_ARE_ADDR_EQUAL(gate, &nh->gw6_sa.sin6_addr)) {
                  return (0);
          }
  
          /*
           * Do not delete a static route.
           * XXX: this seems to be a bit ad-hoc. Should we consider the
           * 'cloned' bit instead?
           */
          nh_rt_flags = nhop_get_rtflags(nh);
          if ((nh_rt_flags & RTF_STATIC) != 0)
                  return (0);
  
          /*
           * We delete only host route. This means, in particular, we don't
           * delete default route.
           */
          if ((nh_rt_flags & RTF_HOST) == 0)
                  return (0);
  
          return (1);
  #undef SIN6
  }
  
  /*
   * Delete all the routing table entries that use the specified gateway.
   * XXX: this function causes search through all entries of routing table, so
   * it shouldn't be called when acting as a router.
   */
  void
  rt6_flush(struct in6_addr *gateway, struct ifnet *ifp)
  {
  
          /* We'll care only link-local addresses */
          if (!IN6_IS_ADDR_LINKLOCAL(gateway))
                  return;
  
          /* XXX Do we really need to walk any but the default FIB? */
          rib_foreach_table_walk_del(AF_INET6, rt6_deleteroute, (void *)gateway);
  }
  
  int
  nd6_setdefaultiface(int ifindex)
  {
          int error = 0;
  
          if (ifindex < 0 || V_if_index < ifindex)
                  return (EINVAL);
          if (ifindex != 0 && !ifnet_byindex(ifindex))
                  return (EINVAL);
  
          if (V_nd6_defifindex != ifindex) {
                  V_nd6_defifindex = ifindex;
                  if (V_nd6_defifindex > 0)
                          V_nd6_defifp = ifnet_byindex(V_nd6_defifindex);
                  else
                          V_nd6_defifp = NULL;
  
                  /*
                   * Our current implementation assumes one-to-one mapping between
                   * interfaces and links, so it would be natural to use the
                   * default interface as the default link.
                   */
                  scope6_setdefault(V_nd6_defifp);
          }
  
          return (error);
  }
  
  bool
  nd6_defrouter_list_empty(void)
  {
  
          return (TAILQ_EMPTY(&V_nd6_defrouter));
  }
  
  void
  nd6_defrouter_timer(void)
  {
          struct nd_defrouter *dr, *ndr;
          struct nd6_drhead drq;
  
          TAILQ_INIT(&drq);
  
          ND6_WLOCK();
          TAILQ_FOREACH_SAFE(dr, &V_nd6_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);
          }
  }
  
  /*
   * 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.
   */
  void
  nd6_defrouter_purge(struct ifnet *ifp)
  {
          struct nd_defrouter *dr, *ndr;
          struct nd6_drhead drq;
  
          TAILQ_INIT(&drq);
  
          ND6_WLOCK();
          TAILQ_FOREACH_SAFE(dr, &V_nd6_defrouter, dr_entry, ndr) {
                  if (dr->installed)
                          continue;
                  if (dr->ifp == ifp)
                          defrouter_unlink(dr, &drq);
          }
          TAILQ_FOREACH_SAFE(dr, &V_nd6_defrouter, dr_entry, ndr) {
                  if (!dr->installed)
                          continue;
                  if (dr->ifp == ifp)
                          defrouter_unlink(dr, &drq);
          }
          ND6_WUNLOCK();
  
          /* Delete the unlinked router objects. */
          while ((dr = TAILQ_FIRST(&drq)) != NULL) {
                  TAILQ_REMOVE(&drq, dr, dr_entry);
                  defrouter_del(dr);
          }
  }
  
  void
  nd6_defrouter_flush_all(void)
  {
          struct nd_defrouter *dr;
          struct nd6_drhead drq;
  
          TAILQ_INIT(&drq);
  
          ND6_WLOCK();
          while ((dr = TAILQ_FIRST(&V_nd6_defrouter)) != NULL)
                  defrouter_unlink(dr, &drq);
          ND6_WUNLOCK();
  
          while ((dr = TAILQ_FIRST(&drq)) != NULL) {
                  TAILQ_REMOVE(&drq, dr, dr_entry);
                  defrouter_del(dr);
          }
  }
  
  void
  nd6_defrouter_init(void)
  {
  
          TAILQ_INIT(&V_nd6_defrouter);
  }
  
  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_nd6_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);
  }
  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");

Cache object: f553e7ec7cceef3bccbe9ca93bef606f