text: /*	$FreeBSD: src/sys/netinet6/nd6_rtr.c,v 1.2.2.5 2003/04/05 10:28:53 ume Exp $	*/
  /*	$KAME: nd6_rtr.c,v 1.111 2001/04/27 01:37:15 jinmei Exp $	*/
  
  /*
   * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the project nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include "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/socket.h>
  #include <sys/sockio.h>
  #include <sys/time.h>
  #include <sys/kernel.h>
  #include <sys/errno.h>
  #include <sys/syslog.h>
  #include <sys/queue.h>
  #include <sys/globaldata.h>
  #include <sys/mutex.h>
  
  #include <sys/thread2.h>
  #include <sys/mutex2.h>
  
  #include <net/if.h>
  #include <net/if_types.h>
  #include <net/if_dl.h>
  #include <net/route.h>
  #include <net/radix.h>
  
  #include <netinet/in.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>
  
  #include <net/net_osdep.h>
  
  #define SDL(s)	((struct sockaddr_dl *)s)
  
  static struct nd_defrouter *defrtrlist_update (struct nd_defrouter *);
  static struct in6_ifaddr *in6_ifadd (struct nd_prefix *,
  	struct in6_addr *);
  static struct nd_pfxrouter *pfxrtr_lookup (struct nd_prefix *,
  	struct nd_defrouter *);
  static void pfxrtr_add (struct nd_prefix *, struct nd_defrouter *);
  static void pfxrtr_del (struct nd_pfxrouter *);
  static struct nd_pfxrouter *find_pfxlist_reachable_router
  	(struct nd_prefix *);
  static void defrouter_addifreq (struct ifnet *);
  
  static void in6_init_address_ltimes (struct nd_prefix *ndpr,
  					 struct in6_addrlifetime *lt6);
  
  static int rt6_deleteroute (struct radix_node *, void *);
  
  extern int nd6_recalc_reachtm_interval;
  
  static struct ifnet *nd6_defifp;
  int nd6_defifindex;
  
  int ip6_use_tempaddr = 0;
  
  int ip6_desync_factor;
  u_int32_t ip6_temp_preferred_lifetime = DEF_TEMP_PREFERRED_LIFETIME;
  u_int32_t ip6_temp_valid_lifetime = DEF_TEMP_VALID_LIFETIME;
  /*
   * shorter lifetimes for debugging purposes.
  int ip6_temp_preferred_lifetime = 800;
  static int ip6_temp_valid_lifetime = 1800;
  */
  int ip6_temp_regen_advance = TEMPADDR_REGEN_ADVANCE;
  
  /*
   * 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 = m->m_pkthdr.rcvif;
  	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  	struct nd_router_solicit *nd_rs;
  	struct in6_addr saddr6 = ip6->ip6_src;
  #if 0
  	struct in6_addr daddr6 = ip6->ip6_dst;
  #endif
  	char *lladdr = NULL;
  	int lladdrlen = 0;
  #if 0
  	struct sockaddr_dl *sdl = NULL;
  	struct llinfo_nd6 *ln = NULL;
  	struct rtentry *rt = NULL;
  	int is_newentry;
  #endif
  	union nd_opts ndopts;
  
  	/* If I'm not a router, ignore it. */
  	if (ip6_accept_rtadv != 0 || ip6_forwarding != 1)
  		goto freeit;
  
  	/* Sanity checks */
  	if (ip6->ip6_hlim != 255) {
  		nd6log((LOG_ERR,
  		    "nd6_rs_input: invalid hlim (%d) from %s to %s on %s\n",
  		    ip6->ip6_hlim, ip6_sprintf(&ip6->ip6_src),
  		    ip6_sprintf(&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.
  	 */
  	if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
  		goto freeit;
  
  #ifndef PULLDOWN_TEST
  	IP6_EXTHDR_CHECK(m, off, icmp6len,);
  	nd_rs = (struct nd_router_solicit *)((caddr_t)ip6 + off);
  #else
  	IP6_EXTHDR_GET(nd_rs, struct nd_router_solicit *, m, off, icmp6len);
  	if (nd_rs == NULL) {
  		icmp6stat.icp6s_tooshort++;
  		return;
  	}
  #endif
  
  	icmp6len -= sizeof(*nd_rs);
  	nd6_option_init(nd_rs + 1, icmp6len, &ndopts);
  	if (nd6_options(&ndopts) < 0) {
  		nd6log((LOG_INFO,
  		    "nd6_rs_input: invalid ND option, ignored\n"));
  		/* nd6_options have incremented stats */
  		goto freeit;
  	}
  
  	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,
  		    "nd6_rs_input: lladdrlen mismatch for %s "
  		    "(if %d, RS packet %d)\n",
  			ip6_sprintf(&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.icp6s_badrs++;
  	m_freem(m);
  }
  
  /*
   * 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 = m->m_pkthdr.rcvif;
  	struct nd_ifinfo *ndi = ND_IFINFO(ifp);
  	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  	struct nd_router_advert *nd_ra;
  	struct in6_addr saddr6 = ip6->ip6_src;
  #if 0
  	struct in6_addr daddr6 = ip6->ip6_dst;
  	int flags; /* = nd_ra->nd_ra_flags_reserved; */
  	int is_managed = ((flags & ND_RA_FLAG_MANAGED) != 0);
  	int is_other = ((flags & ND_RA_FLAG_OTHER) != 0);
  #endif
  	union nd_opts ndopts;
  	struct nd_defrouter *dr;
  
  	/*
  	 * We only accept RAs only when
  	 * the system-wide variable allows the acceptance, and
  	 * per-interface variable allows RAs on the receiving interface.
  	 */
  	if (ip6_accept_rtadv == 0)
  		goto freeit;
  	if (!(ndi->flags & ND6_IFF_ACCEPT_RTADV))
  		goto freeit;
  
  	if (ip6->ip6_hlim != 255) {
  		nd6log((LOG_ERR,
  		    "nd6_ra_input: invalid hlim (%d) from %s to %s on %s\n",
  		    ip6->ip6_hlim, ip6_sprintf(&ip6->ip6_src),
  		    ip6_sprintf(&ip6->ip6_dst), if_name(ifp)));
  		goto bad;
  	}
  
  	if (!IN6_IS_ADDR_LINKLOCAL(&saddr6)) {
  		nd6log((LOG_ERR,
  		    "nd6_ra_input: src %s is not link-local\n",
  		    ip6_sprintf(&saddr6)));
  		goto bad;
  	}
  
  #ifndef PULLDOWN_TEST
  	IP6_EXTHDR_CHECK(m, off, icmp6len,);
  	nd_ra = (struct nd_router_advert *)((caddr_t)ip6 + off);
  #else
  	IP6_EXTHDR_GET(nd_ra, struct nd_router_advert *, m, off, icmp6len);
  	if (nd_ra == NULL) {
  		icmp6stat.icp6s_tooshort++;
  		return;
  	}
  #endif
  
  	icmp6len -= sizeof(*nd_ra);
  	nd6_option_init(nd_ra + 1, icmp6len, &ndopts);
  	if (nd6_options(&ndopts) < 0) {
  		nd6log((LOG_INFO,
  		    "nd6_ra_input: invalid ND option, ignored\n"));
  		/* nd6_options have incremented stats */
  		goto freeit;
  	}
  
      {
  	struct nd_defrouter dr0;
  	u_int32_t advreachable = nd_ra->nd_ra_reachable;
  
  	dr0.rtaddr = saddr6;
  	dr0.flags  = nd_ra->nd_ra_flags_reserved;
  	dr0.rtlifetime = ntohs(nd_ra->nd_ra_router_lifetime);
  	dr0.expire = time_second + dr0.rtlifetime;
  	dr0.ifp = ifp;
  	dr0.advint = 0;		/* Mobile IPv6 */
  	dr0.advint_expire = 0;	/* Mobile IPv6 */
  	dr0.advints_lost = 0;	/* Mobile IPv6 */
  	/* 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 = 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)
  		ndi->chlim = nd_ra->nd_ra_curhoplimit;
  	dr = defrtrlist_update(&dr0);
      }
  
  	/*
  	 * prefix
  	 */
  	if (ndopts.nd_opts_pi) {
  		struct nd_opt_hdr *pt;
  		struct nd_opt_prefix_info *pi = NULL;
  		struct nd_prefix 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,
  				    "nd6_ra_input: invalid option "
  				    "len %d for prefix information option, "
  				    "ignored\n", pi->nd_opt_pi_len));
  				continue;
  			}
  
  			if (128 < pi->nd_opt_pi_prefix_len) {
  				nd6log((LOG_INFO,
  				    "nd6_ra_input: invalid prefix "
  				    "len %d for prefix information option, "
  				    "ignored\n", 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,
  				    "nd6_ra_input: invalid prefix "
  				    "%s, ignored\n",
  				    ip6_sprintf(&pi->nd_opt_pi_prefix)));
  				continue;
  			}
  
  			/* aggregatable unicast address, rfc2374 */
  			if ((pi->nd_opt_pi_prefix.s6_addr8[0] & 0xe0) == 0x20
  			 && pi->nd_opt_pi_prefix_len != 64) {
  				nd6log((LOG_INFO,
  				    "nd6_ra_input: invalid prefixlen "
  				    "%d for rfc2374 prefix %s, ignored\n",
  				    pi->nd_opt_pi_prefix_len,
  				    ip6_sprintf(&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_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);
  
  			if (in6_init_prefix_ltimes(&pr))
  				continue; /* prefix lifetime init failed */
  
  			prelist_update(&pr, dr, m);
  		}
  	}
  
  	/*
  	 * MTU
  	 */
  	if (ndopts.nd_opts_mtu && ndopts.nd_opts_mtu->nd_opt_mtu_len == 1) {
  		u_int32_t mtu = ntohl(ndopts.nd_opts_mtu->nd_opt_mtu_mtu);
  
  		/* lower bound */
  		if (mtu < IPV6_MMTU) {
  			nd6log((LOG_INFO, "nd6_ra_input: bogus mtu option "
  			    "mtu=%d sent from %s, ignoring\n",
  			    mtu, ip6_sprintf(&ip6->ip6_src)));
  			goto skip;
  		}
  
  		/* upper bound */
  		if (ndi->maxmtu) {
  			if (mtu <= ndi->maxmtu) {
  				int change = (ndi->linkmtu != mtu);
  
  				ndi->linkmtu = mtu;
  				if (change) /* in6_maxmtu may change */
  					in6_setmaxmtu();
  			} else {
  				nd6log((LOG_INFO, "nd6_ra_input: bogus mtu "
  				    "mtu=%d sent from %s; "
  				    "exceeds maxmtu %d, ignoring\n",
  				    mtu, ip6_sprintf(&ip6->ip6_src),
  				    ndi->maxmtu));
  			}
  		} else {
  			nd6log((LOG_INFO, "nd6_ra_input: mtu option "
  			    "mtu=%d sent from %s; maxmtu unknown, "
  			    "ignoring\n",
  			    mtu, ip6_sprintf(&ip6->ip6_src)));
  		}
  	}
  
  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,
  		    "nd6_ra_input: lladdrlen mismatch for %s "
  		    "(if %d, RA packet %d)\n",
  			ip6_sprintf(&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.icp6s_badra++;
  	m_freem(m);
  }
  
  /*
   * default router list proccessing sub routines
   */
  
  #if 0
  /* tell the change to user processes watching the routing socket. */
  static void
  nd6_rtmsg(int cmd, struct rtentry *rt)
  {
  	struct rt_addrinfo info;
  
  	bzero((caddr_t)&info, sizeof(info));
  	info.rti_info[RTAX_DST] = rt_key(rt);
  	info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
  	info.rti_info[RTAX_NETMASK] = rt_mask(rt);
  	if (TAILQ_EMPTY(&rt->rt_ifp->if_addrheads[mycpuid])) {
  		info.rti_info[RTAX_IFP] = NULL;
  	} else {
  		info.rti_info[RTAX_IFP] =
  		(struct sockaddr *)
  		TAILQ_FIRST(&rt->rt_ifp->if_addrheads[mycpuid])->ifa;
  	}
  	info.rti_info[RTAX_IFA] = rt->rt_ifa->ifa_addr;
  
  	rt_missmsg(cmd, &info, rt->rt_flags, 0);
  }
  #endif
  
  void
  defrouter_addreq(struct nd_defrouter *new)
  {
  	struct sockaddr_in6 def, mask, gate;
  
  	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 = mask.sin6_family = gate.sin6_family = AF_INET6;
  	gate.sin6_addr = new->rtaddr;
  
  	rtrequest_global(RTM_ADD, (struct sockaddr *)&def,
  			 (struct sockaddr *)&gate, (struct sockaddr *)&mask,
  			 RTF_GATEWAY);
  	return;
  }
  
  /* Add a route to a given interface as default */
  void
  defrouter_addifreq(struct ifnet *ifp)
  {
  	struct sockaddr_in6 def, mask;
  	struct ifaddr *ifa;
  	int error, flags;
  
  	bzero(&def, sizeof(def));
  	bzero(&mask, sizeof(mask));
  
  	def.sin6_len = mask.sin6_len = sizeof(struct sockaddr_in6);
  	def.sin6_family = mask.sin6_family = AF_INET6;
  
  	/*
  	 * Search for an ifaddr beloging to the specified interface.
  	 * XXX: An IPv6 address are required to be assigned on the interface.
  	 */
  	if ((ifa = ifaof_ifpforaddr((struct sockaddr *)&def, ifp)) == NULL) {
  		nd6log((LOG_ERR,	/* better error? */
  		    "defrouter_addifreq: failed to find an ifaddr "
  		    "to install a route to interface %s\n",
  		    if_name(ifp)));
  		return;
  	}
  
  	flags = ifa->ifa_flags;
  	error = rtrequest_global(RTM_ADD,
  				 (struct sockaddr *)&def,
  				 ifa->ifa_addr,
  				 (struct sockaddr *)&mask,
  				 flags);
  	if (error != 0) {
  		nd6log((LOG_ERR,
  		    "defrouter_addifreq: failed to install a route to "
  		    "interface %s (errno = %d)\n",
  		    if_name(ifp), error));
  	}
  }
  
  struct nd_defrouter *
  defrouter_lookup(struct in6_addr *addr, struct ifnet *ifp)
  {
  	struct nd_defrouter *dr;
  
  	for (dr = TAILQ_FIRST(&nd_defrouter); dr;
  	     dr = TAILQ_NEXT(dr, dr_entry)) {
  		if (dr->ifp == ifp && IN6_ARE_ADDR_EQUAL(addr, &dr->rtaddr))
  			return (dr);
  	}
  
  	return (NULL);		/* search failed */
  }
  
  void
  defrouter_delreq(struct nd_defrouter *dr, int dofree)
  {
  	struct sockaddr_in6 def, mask, gate;
  
  	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 = mask.sin6_family = gate.sin6_family = AF_INET6;
  	gate.sin6_addr = dr->rtaddr;
  
  	rtrequest_global(RTM_DELETE,
  			 (struct sockaddr *)&def,
  			 (struct sockaddr *)&gate,
  			 (struct sockaddr *)&mask,
  			 RTF_GATEWAY);
  	if (dofree)		/* XXX: necessary? */
  		kfree(dr, M_IP6NDP);
  }
  
  void
  defrtrlist_del(struct nd_defrouter *dr)
  {
  	struct nd_defrouter *deldr = NULL;
  	struct nd_prefix *pr;
  
  	/*
  	 * Flush all the routing table entries that use the router
  	 * as a next hop.
  	 */
  	if (!ip6_forwarding && ip6_accept_rtadv) {
  		/* above is a good condition? */
  		rt6_flush(&dr->rtaddr, dr->ifp);
  	}
  
  	if (dr == TAILQ_FIRST(&nd_defrouter))
  		deldr = dr;	/* The router is primary. */
  
  	TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
  
  	/*
  	 * Also delete all the pointers to the router in each prefix lists.
  	 */
  	for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
  		struct nd_pfxrouter *pfxrtr;
  		if ((pfxrtr = pfxrtr_lookup(pr, dr)) != NULL)
  			pfxrtr_del(pfxrtr);
  	}
  	pfxlist_onlink_check();
  
  	/*
  	 * If the router is the primary one, choose a new one.
  	 * Note that defrouter_select() will remove the current gateway
  	 * from the routing table.
  	 */
  	if (deldr)
  		defrouter_select();
  
  	kfree(dr, M_IP6NDP);
  }
  
  /*
   * Default Router Selection according to Section 6.3.6 of RFC 2461:
   * 1) Routers that are reachable or probably reachable should be
   *    preferred.
   * 2) When no routers on the list are known to be reachable or
   *    probably reachable, routers SHOULD be selected in a round-robin
   *    fashion.
   * 3) If the Default Router List is empty, assume that all
   *    destinations are on-link.
   */
  void
  defrouter_select(void)
  {
  	struct nd_defrouter *dr, anydr;
  	struct rtentry *rt = NULL;
  	struct llinfo_nd6 *ln = NULL;
  
  	mtx_lock(&nd6_mtx);
  
  	/*
  	 * Search for a (probably) reachable router from the list.
  	 */
  	for (dr = TAILQ_FIRST(&nd_defrouter); dr;
  	     dr = TAILQ_NEXT(dr, dr_entry)) {
  		if ((rt = nd6_lookup(&dr->rtaddr, 0, dr->ifp)) &&
  		    (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
  		    ND6_IS_LLINFO_PROBREACH(ln)) {
  			/* Got it, and move it to the head */
  			TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
  			TAILQ_INSERT_HEAD(&nd_defrouter, dr, dr_entry);
  			break;
  		}
  	}
  
  	if ((dr = TAILQ_FIRST(&nd_defrouter))) {
  		/*
  		 * De-install the previous default gateway and install
  		 * a new one.
  		 * Note that if there is no reachable router in the list,
  		 * the head entry will be used anyway.
  		 * XXX: do we have to check the current routing table entry?
  		 */
  		bzero(&anydr, sizeof(anydr));
  		defrouter_delreq(&anydr, 0);
  		defrouter_addreq(dr);
  	}
  	else {
  		/*
  		 * The Default Router List is empty, so install the default
  		 * route to an inteface.
  		 * XXX: The specification does not say this mechanism should
  		 * be restricted to hosts, but this would be not useful
  		 * (even harmful) for routers.
  		 */
  		if (!ip6_forwarding) {
  			/*
  			 * De-install the current default route
  			 * in advance.
  			 */
  			bzero(&anydr, sizeof(anydr));
  			defrouter_delreq(&anydr, 0);
  			if (nd6_defifp) {
  				/*
  				 * Install a route to the default interface
  				 * as default route.
  				 * XXX: we enable this for host only, because
  				 * this may override a default route installed
  				 * a user process (e.g. routing daemon) in a
  				 * router case.
  				 */
  				defrouter_addifreq(nd6_defifp);
  			} else {
  				nd6log((LOG_INFO, "defrouter_select: "
  				    "there's no default router and no default"
  				    " interface\n"));
  			}
  		}
  	}
  	mtx_unlock(&nd6_mtx);
  	return;
  }
  
  static struct nd_defrouter *
  defrtrlist_update(struct nd_defrouter *new)
  {
  	struct nd_defrouter *dr, *n;
  
  	mtx_lock(&nd6_mtx);
  
  	if ((dr = defrouter_lookup(&new->rtaddr, new->ifp)) != NULL) {
  		/* entry exists */
  		if (new->rtlifetime == 0) {
  			defrtrlist_del(dr);
  			dr = NULL;
  		} else {
  			/* override */
  			dr->flags = new->flags; /* xxx flag check */
  			dr->rtlifetime = new->rtlifetime;
  			dr->expire = new->expire;
  		}
  		mtx_unlock(&nd6_mtx);
  		return (dr);
  	}
  
  	/* entry does not exist */
  	if (new->rtlifetime == 0) {
  		mtx_unlock(&nd6_mtx);
  		return (NULL);
  	}
  
  	n = (struct nd_defrouter *)kmalloc(sizeof(*n), M_IP6NDP,
  	    M_NOWAIT | M_ZERO);
  	if (n == NULL) {
  		mtx_unlock(&nd6_mtx);
  		return (NULL);
  	}
  	*n = *new;
  
  	/*
  	 * Insert the new router at the end of the Default Router List.
  	 * If there is no other router, install it anyway. Otherwise,
  	 * just continue to use the current default router.
  	 */
  	TAILQ_INSERT_TAIL(&nd_defrouter, n, dr_entry);
  	if (TAILQ_FIRST(&nd_defrouter) == n)
  		defrouter_select();
  	mtx_unlock(&nd6_mtx);
  	return (n);
  }
  
  static struct nd_pfxrouter *
  pfxrtr_lookup(struct nd_prefix *pr, struct nd_defrouter *dr)
  {
  	struct nd_pfxrouter *search;
  
  	for (search = pr->ndpr_advrtrs.lh_first; search; search = search->pfr_next) {
  		if (search->router == dr)
  			break;
  	}
  
  	return (search);
  }
  
  static void
  pfxrtr_add(struct nd_prefix *pr, struct nd_defrouter *dr)
  {
  	struct nd_pfxrouter *new;
  
  	new = (struct nd_pfxrouter *)kmalloc(sizeof(*new), M_IP6NDP,
  	    M_NOWAIT | M_ZERO);
  	if (new == NULL)
  		return;
  	new->router = dr;
  
  	LIST_INSERT_HEAD(&pr->ndpr_advrtrs, new, pfr_entry);
  
  	pfxlist_onlink_check();
  }
  
  static void
  pfxrtr_del(struct nd_pfxrouter *pfr)
  {
  	LIST_REMOVE(pfr, pfr_entry);
  	kfree(pfr, M_IP6NDP);
  }
  
  struct nd_prefix *
  nd6_prefix_lookup(struct nd_prefix *pr)
  {
  	struct nd_prefix *search;
  
  	for (search = nd_prefix.lh_first; search; search = search->ndpr_next) {
  		if (pr->ndpr_ifp == search->ndpr_ifp &&
  		    pr->ndpr_plen == search->ndpr_plen &&
  		    in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
  					 &search->ndpr_prefix.sin6_addr,
  					 pr->ndpr_plen)
  		    ) {
  			break;
  		}
  	}
  
  	return (search);
  }
  
  int
  nd6_prelist_add(struct nd_prefix *pr, struct nd_defrouter *dr,
  		struct nd_prefix **newp)
  {
  	struct nd_prefix *new = NULL;
  	int i;
  
  	new = (struct nd_prefix *)kmalloc(sizeof(*new), M_IP6NDP,
  	    M_NOWAIT | M_ZERO);
  	if (new == NULL)
  		return ENOMEM;
  	*new = *pr;
  	if (newp != NULL)
  		*newp = new;
  
  	/* initilization */
  	LIST_INIT(&new->ndpr_advrtrs);
  	in6_prefixlen2mask(&new->ndpr_mask, new->ndpr_plen);
  	/* make prefix in the canonical form */
  	for (i = 0; i < 4; i++)
  		new->ndpr_prefix.sin6_addr.s6_addr32[i] &=
  			new->ndpr_mask.s6_addr32[i];
  
  	mtx_lock(&nd6_mtx);
  	/* link ndpr_entry to nd_prefix list */
  	LIST_INSERT_HEAD(&nd_prefix, new, ndpr_entry);
  	mtx_unlock(&nd6_mtx);
  
  	/* ND_OPT_PI_FLAG_ONLINK processing */
  	if (new->ndpr_raf_onlink) {
  		int e;
  
  		if ((e = nd6_prefix_onlink(new)) != 0) {
  			nd6log((LOG_ERR, "nd6_prelist_add: failed to make "
  			    "the prefix %s/%d on-link on %s (errno=%d)\n",
  			    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  			    pr->ndpr_plen, if_name(pr->ndpr_ifp), e));
  			/* proceed anyway. XXX: is it correct? */
  		}
  	}
  
  	if (dr) {
  		pfxrtr_add(new, dr);
  	}
  
  	return 0;
  }
  
  void
  prelist_remove(struct nd_prefix *pr)
  {
  	struct nd_pfxrouter *pfr, *next;
  	int e;
  
  	/* make sure to invalidate the prefix until it is really freed. */
  	pr->ndpr_vltime = 0;
  	pr->ndpr_pltime = 0;
  #if 0
  	/*
  	 * Though these flags are now meaningless, we'd rather keep the value
  	 * not to confuse users when executing "ndp -p".
  	 */
  	pr->ndpr_raf_onlink = 0;
  	pr->ndpr_raf_auto = 0;
  #endif
  	if ((pr->ndpr_stateflags & NDPRF_ONLINK) &&
  	    (e = nd6_prefix_offlink(pr)) != 0) {
  		nd6log((LOG_ERR, "prelist_remove: failed to make %s/%d offlink "
  		    "on %s, errno=%d\n",
  		    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  		    pr->ndpr_plen, if_name(pr->ndpr_ifp), e));
  		/* what should we do? */
  	}
  
  	if (pr->ndpr_refcnt > 0)
  		return;		/* notice here? */
  
  	mtx_lock(&nd6_mtx);
  
  	/* unlink ndpr_entry from nd_prefix list */
  	LIST_REMOVE(pr, ndpr_entry);
  
  	/* free list of routers that adversed the prefix */
  	for (pfr = pr->ndpr_advrtrs.lh_first; pfr; pfr = next) {
  		next = pfr->pfr_next;
  
  		kfree(pfr, M_IP6NDP);
  	}
  	mtx_unlock(&nd6_mtx);
  
  	kfree(pr, M_IP6NDP);
  
  	pfxlist_onlink_check();
  }
  
  /*
   * Parameters:
   *	dr:	may be NULL
   */
  int
  prelist_update(struct nd_prefix *new, struct nd_defrouter *dr, struct mbuf *m)
  {
  	struct in6_ifaddr *ia6 = NULL, *ia6_match = NULL;
  	struct ifaddr_container *ifac;
  	struct ifnet *ifp = new->ndpr_ifp;
  	struct nd_prefix *pr;
  	int error = 0;
  	int newprefix = 0;
  	int auth;
  	struct in6_addrlifetime lt6_tmp;
  
  	auth = 0;
  	mtx_lock(&nd6_mtx);
  	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) ? 1 : 0;
  #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;
  			pr->ndpr_preferred = new->ndpr_preferred;
  			pr->ndpr_expire = new->ndpr_expire;
  		}
  
  		if (new->ndpr_raf_onlink &&
  		    !(pr->ndpr_stateflags & NDPRF_ONLINK)) {
  			int e;
  
  			if ((e = nd6_prefix_onlink(pr)) != 0) {
  				nd6log((LOG_ERR,
  				    "prelist_update: failed to make "
  				    "the prefix %s/%d on-link on %s "
  				    "(errno=%d)\n",
  				    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  				    pr->ndpr_plen, if_name(pr->ndpr_ifp), e));
  				/* proceed anyway. XXX: is it correct? */
  			}
  		}
  
  		if (dr && pfxrtr_lookup(pr, dr) == NULL)
  			pfxrtr_add(pr, dr);
  	} else {
  		struct nd_prefix *newpr = NULL;
  
  		newprefix = 1;
  
  		if (new->ndpr_vltime == 0)
  			goto end;
  		if (new->ndpr_raf_onlink == 0 && new->ndpr_raf_auto == 0)
  			goto end;
  
  		bzero(&new->ndpr_addr, sizeof(struct in6_addr));
  
  		error = nd6_prelist_add(new, dr, &newpr);
  		if (error != 0 || newpr == NULL) {
  			nd6log((LOG_NOTICE, "prelist_update: "
  			    "nd6_prelist_add failed for %s/%d on %s "
  			    "errno=%d, returnpr=%p\n",
  			    ip6_sprintf(&new->ndpr_prefix.sin6_addr),
  					new->ndpr_plen, if_name(new->ndpr_ifp),
  					error, newpr));
  			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 suret that the prefix
  		 * itself expires now.
  		 */
  		if (newpr->ndpr_raf_onlink == 0) {
  			newpr->ndpr_vltime = 0;
  			newpr->ndpr_pltime = 0;
  			in6_init_prefix_ltimes(newpr);
  		}
  
  		pr = newpr;
  	}
  
  	/*
  	 * 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 afteraddrconf;
  
  	/*
  	 * 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.
  	 * This should have been done in nd6_ra_input.
  	 */
  
   	/*
  	 * 5.5.3 (d). If the prefix advertised does not match the prefix of an
  	 * address already in the list, and the Valid Lifetime is not 0,
  	 * form an address.  Note that even a manually configured address
  	 * should reject autoconfiguration of a new address.
  	 */
  	TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
  		struct ifaddr *ifa = ifac->ifa;
  		struct in6_ifaddr *ifa6;
  		int ifa_plen;
  		u_int32_t storedlifetime;
  
  		if (ifa->ifa_addr->sa_family != AF_INET6)
  			continue;
  
  		ifa6 = (struct in6_ifaddr *)ifa;
  
  		/*
  		 * 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)
  			continue;
  
  		ifa_plen = in6_mask2len(&ifa6->ia_prefixmask.sin6_addr, NULL);
  		if (ifa_plen != new->ndpr_plen ||
  		    !in6_are_prefix_equal(&ifa6->ia_addr.sin6_addr,
  					  &new->ndpr_prefix.sin6_addr,
  					  ifa_plen))
  			continue;
  
  		if (ia6_match == NULL) /* remember the first one */
  			ia6_match = ifa6;
  
  		if (!(ifa6->ia6_flags & IN6_IFF_AUTOCONF))
  			continue;
  
  		/*
  		 * 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.
  		 */
  #define TWOHOUR		(120*60)
  		lt6_tmp = ifa6->ia6_lifetime;
  
  		if (lt6_tmp.ia6t_vltime == ND6_INFINITE_LIFETIME)
  			storedlifetime = ND6_INFINITE_LIFETIME;
  		else if (IFA6_IS_INVALID(ifa6))
  			storedlifetime = 0;
  		else
  			storedlifetime = lt6_tmp.ia6t_expire - time_second;
  
  		/* when not updating, keep the current stored lifetime. */
  		lt6_tmp.ia6t_vltime = storedlifetime;
  
  		if (TWOHOUR < new->ndpr_vltime ||
  		    storedlifetime < new->ndpr_vltime) {
  			lt6_tmp.ia6t_vltime = new->ndpr_vltime;
  		} else if (storedlifetime <= TWOHOUR
  #if 0
  			   /*
  			    * This condition is logically redundant, so we just
  			    * omit it.
  			    * See IPng 6712, 6717, and 6721.
  			    */
  			   && new->ndpr_vltime <= storedlifetime
  #endif
  			) {
  			if (auth) {
  				lt6_tmp.ia6t_vltime = new->ndpr_vltime;
  			}
  		} else {
  			/*
  			 * new->ndpr_vltime <= TWOHOUR &&
  			 * TWOHOUR < storedlifetime
  			 */
  			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);
  
  		/*
  		 * When adjusting the lifetimes of an existing temporary
  		 * address, only lower the lifetimes.
  		 * RFC 3041 3.3. (1).
  		 * XXX: how should we modify ia6t_[pv]ltime?
  		 */
  		if (ifa6->ia6_flags & IN6_IFF_TEMPORARY) {
  			if (lt6_tmp.ia6t_expire == 0 || /* no expire */
  			    lt6_tmp.ia6t_expire >
  			    ifa6->ia6_lifetime.ia6t_expire) {
  				lt6_tmp.ia6t_expire =
  					ifa6->ia6_lifetime.ia6t_expire;
  			}
  			if (lt6_tmp.ia6t_preferred == 0 || /* no expire */
  			    lt6_tmp.ia6t_preferred >
  			    ifa6->ia6_lifetime.ia6t_preferred) {
  				lt6_tmp.ia6t_preferred =
  					ifa6->ia6_lifetime.ia6t_preferred;
  			}
  		}
  
  		ifa6->ia6_lifetime = lt6_tmp;
  	}
  	if (ia6_match == NULL && new->ndpr_vltime) {
  		/*
  		 * No address matched and the valid lifetime is non-zero.
  		 * Create a new address.
  		 */
  		if ((ia6 = in6_ifadd(new, NULL)) != NULL) {
  			/*
  			 * note that we should use pr (not new) for reference.
  			 */
  			pr->ndpr_refcnt++;
  			ia6->ia6_ndpr = pr;
  
  #if 0
  			/* XXXYYY Don't do this, according to Jinmei. */
  			pr->ndpr_addr = new->ndpr_addr;
  #endif
  
  			/*
  			 * 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 (ip6_use_tempaddr) {
  				int e;
  				if ((e = in6_tmpifadd(ia6, 1)) != 0) {
  					nd6log((LOG_NOTICE, "prelist_update: "
  					    "failed to create a temporary "
  					    "address, errno=%d\n",
  					    e));
  				}
  			}
  
  			/*
  			 * 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. */
  		}
  	}
  
  afteraddrconf:
  
  end:
  	mtx_unlock(&nd6_mtx);
  	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 nd_pfxrouter *pfxrtr;
  	struct rtentry *rt;
  	struct llinfo_nd6 *ln;
  
  	for (pfxrtr = LIST_FIRST(&pr->ndpr_advrtrs); pfxrtr;
  	     pfxrtr = LIST_NEXT(pfxrtr, pfr_entry)) {
  		if ((rt = nd6_lookup(&pfxrtr->router->rtaddr, 0,
  				     pfxrtr->router->ifp)) &&
  		    (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
  		    ND6_IS_LLINFO_PROBREACH(ln))
  			break;	/* found */
  	}
  
  	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 regards
   * 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;
  
  	/*
  	 * Check if there is a prefix that has a reachable advertising
  	 * router.
  	 */
  	for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
  		if (pr->ndpr_raf_onlink && find_pfxlist_reachable_router(pr))
  			break;
  	}
  
  	if (pr) {
  		/*
  		 * There is at least one prefix that has a reachable router.
  		 * Detach prefixes which have no reachable advertising
  		 * router, and attach other prefixes.
  		 */
  		for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
  			/* XXX: a link-local prefix should never be detached */
  			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
  				continue;
  
  			/*
  			 * we aren't interested in prefixes without the L bit
  			 * set.
  			 */
  			if (pr->ndpr_raf_onlink == 0)
  				continue;
  
  			if (!(pr->ndpr_stateflags & NDPRF_DETACHED) &&
  			    find_pfxlist_reachable_router(pr) == NULL)
  				pr->ndpr_stateflags |= NDPRF_DETACHED;
  			if ((pr->ndpr_stateflags & NDPRF_DETACHED) &&
  			    find_pfxlist_reachable_router(pr) != NULL)
  				pr->ndpr_stateflags &= ~NDPRF_DETACHED;
  		}
  	} else {
  		/* there is no prefix that has a reachable router */
  		for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
  			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
  				continue;
  
  			if (pr->ndpr_raf_onlink == 0)
  				continue;
  
  			if (pr->ndpr_stateflags & NDPRF_DETACHED)
  				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.
  	 */
  	for (pr = nd_prefix.lh_first; pr; pr = pr->ndpr_next) {
  		int e;
  
  		if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
  			continue;
  
  		if (pr->ndpr_raf_onlink == 0)
  			continue;
  
  		if ((pr->ndpr_stateflags & NDPRF_DETACHED) &&
  		    (pr->ndpr_stateflags & NDPRF_ONLINK)) {
  			if ((e = nd6_prefix_offlink(pr)) != 0) {
  				nd6log((LOG_ERR,
  				    "pfxlist_onlink_check: failed to "
  				    "make %s/%d offlink, errno=%d\n",
  				    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  				    pr->ndpr_plen, e));
  			}
  		}
  		if (!(pr->ndpr_stateflags & NDPRF_DETACHED) &&
  		    !(pr->ndpr_stateflags & NDPRF_ONLINK) &&
  		    pr->ndpr_raf_onlink) {
  			if ((e = nd6_prefix_onlink(pr)) != 0) {
  				nd6log((LOG_ERR,
  				    "pfxlist_onlink_check: failed to "
  				    "make %s/%d offlink, errno=%d\n",
  				    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  				    pr->ndpr_plen, e));
  			}
  		}
  	}
  
  	/*
  	 * 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.
  	 */
  	for (ifa = in6_ifaddr; ifa; ifa = ifa->ia_next) {
  		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) {
  		for (ifa = in6_ifaddr; ifa; ifa = ifa->ia_next) {
  			if (!(ifa->ia6_flags & IN6_IFF_AUTOCONF))
  				continue;
  
  			if (ifa->ia6_ndpr == NULL) /* XXX: see above. */
  				continue;
  
  			if (find_pfxlist_reachable_router(ifa->ia6_ndpr))
  				ifa->ia6_flags &= ~IN6_IFF_DETACHED;
  			else
  				ifa->ia6_flags |= IN6_IFF_DETACHED;
  		}
  	}
  	else {
  		for (ifa = in6_ifaddr; ifa; ifa = ifa->ia_next) {
  			if (!(ifa->ia6_flags & IN6_IFF_AUTOCONF))
  				continue;
  
  			ifa->ia6_flags &= ~IN6_IFF_DETACHED;
  		}
  	}
  }
  
  int
  nd6_prefix_onlink(struct nd_prefix *pr)
  {
  	struct ifaddr *ifa;
  	struct ifnet *ifp = pr->ndpr_ifp;
  	struct sockaddr_in6 mask6;
  	struct nd_prefix *opr;
  	u_long rtflags;
  	int error = 0;
  
  	/* sanity check */
  	if (pr->ndpr_stateflags & NDPRF_ONLINK) {
  		nd6log((LOG_ERR,
  		    "nd6_prefix_onlink: %s/%d is already on-link\n",
  		    ip6_sprintf(&pr->ndpr_prefix.sin6_addr), pr->ndpr_plen);
  		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.
  	 */
  	for (opr = nd_prefix.lh_first; opr; opr = opr->ndpr_next) {
  		if (opr == pr)
  			continue;
  
  		if (!(opr->ndpr_stateflags & NDPRF_ONLINK))
  			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))
  			return (0);
  	}
  
  	/*
  	 * We prefer link-local addresses as the associated interface address.
  	 */
  	/* search for a link-local addr */
  	ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp,
  						      IN6_IFF_NOTREADY|
  						      IN6_IFF_ANYCAST);
  	if (ifa == NULL) {
  		struct ifaddr_container *ifac;
  
  		/* XXX: freebsd does not have ifa_ifwithaf */
  		TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
  			if (ifac->ifa->ifa_addr->sa_family == AF_INET6) {
  				ifa = ifac->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,
  		    "nd6_prefix_onlink: failed to find any ifaddr"
  		    " to add route for a prefix(%s/%d) on %s\n",
  		    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  		    pr->ndpr_plen, if_name(ifp)));
  		return (0);
  	}
  
  	/*
  	 * in6_ifinit() sets nd6_rtrequest to ifa_rtrequest for all ifaddrs.
  	 * ifa->ifa_rtrequest = nd6_rtrequest;
  	 */
  	bzero(&mask6, sizeof(mask6));
  	mask6.sin6_len = sizeof(mask6);
  	mask6.sin6_addr = pr->ndpr_mask;
  	rtflags = ifa->ifa_flags | RTF_CLONING | RTF_UP;
  	if (nd6_need_cache(ifp)) {
  		/* explicitly set in case ifa_flags does not set the flag. */
  		rtflags |= RTF_CLONING;
  	} else {
  		/*
  		 * explicitly clear the cloning bit in case ifa_flags sets it.
  		 */
  		rtflags &= ~RTF_CLONING;
  	}
  	error = rtrequest_global(RTM_ADD,
  				 (struct sockaddr *)&pr->ndpr_prefix,
  				 ifa->ifa_addr,
  				 (struct sockaddr *)&mask6,
  				 rtflags);
  	if (error == 0) {
  		pr->ndpr_stateflags |= NDPRF_ONLINK;
  	}
  	else {
  		nd6log((LOG_ERR, "nd6_prefix_onlink: failed to add route for a"
  		    " prefix (%s/%d) on %s, gw=%s, mask=%s, flags=%lx "
  		    "errno = %d\n",
  		    ip6_sprintf(&pr->ndpr_prefix.sin6_addr),
  		    pr->ndpr_plen, if_name(ifp),
  		    ip6_sprintf(&((struct sockaddr_in6 *)ifa->ifa_addr)->sin6_addr),
  		    ip6_sprintf(&mask6.sin6_addr), rtflags, error));
  	}
  	return (error);
  }
  
  int
  nd6_prefix_offlink(struct nd_prefix *pr)
  {
  	int error = 0;
  	struct ifnet *ifp = pr->ndpr_ifp;
  	struct nd_prefix *opr;
  	struct sockaddr_in6 sa6, mask6;
  
  	/* sanity check */
  	if (!(pr->ndpr_stateflags & NDPRF_ONLINK)) {
  		nd6log((LOG_ERR,
  		    "nd6_prefix_offlink: %s/%d is already off-link\n",
  		    ip6_sprintf(&pr->ndpr_prefix.sin6_addr), pr->ndpr_plen));
  		return (EEXIST);
  	}
  
  	bzero(&sa6, sizeof(sa6));
  	sa6.sin6_family = AF_INET6;
  	sa6.sin6_len = sizeof(sa6);
  	bcopy(&pr->ndpr_prefix.sin6_addr, &sa6.sin6_addr,
  	      sizeof(struct in6_addr));
  	bzero(&mask6, sizeof(mask6));
  	mask6.sin6_family = AF_INET6;
  	mask6.sin6_len = sizeof(sa6);
  	bcopy(&pr->ndpr_mask, &mask6.sin6_addr, sizeof(struct in6_addr));
  	error = rtrequest_global(RTM_DELETE,
  				 (struct sockaddr *)&sa6,
  				 NULL,
  				 (struct sockaddr *)&mask6,
  				 0);
  	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.
  		 */
  		for (opr = nd_prefix.lh_first; opr; opr = opr->ndpr_next) {
  			if (opr == pr)
  				continue;
  
  			if (opr->ndpr_stateflags & NDPRF_ONLINK)
  				continue;
  
  			/*
  			 * KAME specific: detached prefixes should not be
  			 * on-link.
  			 */
  			if (opr->ndpr_stateflags & NDPRF_DETACHED)
  				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;
  
  				if ((e = nd6_prefix_onlink(opr)) != 0) {
  					nd6log((LOG_ERR,
  					    "nd6_prefix_offlink: failed to "
  					    "recover a prefix %s/%d from %s "
  					    "to %s (errno = %d)\n",
  					    ip6_sprintf(&opr->ndpr_prefix.sin6_addr),
  					    opr->ndpr_plen, if_name(ifp),
  					    if_name(opr->ndpr_ifp), e));
  				}
  			}
  		}
  	}
  	else {
  		/* XXX: can we still set the NDPRF_ONLINK flag? */
  		nd6log((LOG_ERR,
  		    "nd6_prefix_offlink: failed to delete route: "
  		    "%s/%d on %s (errno = %d)\n",
  		    ip6_sprintf(&sa6.sin6_addr), pr->ndpr_plen, if_name(ifp),
  		    error));
  	}
  
  	return (error);
  }
  
  /*
   * Parameters:
   *	ifid:	Mobile IPv6 addition
   */
  static struct in6_ifaddr *
  in6_ifadd(struct nd_prefix *pr, struct in6_addr *ifid)
  {
  	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;
  
  	in6_len2mask(&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 a 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.
  	 *
  	 * Mobile IPv6 addition: allow for caller to specify a wished interface
  	 * ID. This is to not break connections when moving addresses between
  	 * interfaces.
  	 */
  	ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0);/* 0 is OK? */
  	if (ifa)
  		ib = (struct in6_ifaddr *)ifa;
  	else
  		return NULL;
  
  #if 0 /* don't care link local addr state, and always do DAD */
  	/* if link-local address is not eligible, do not autoconfigure. */
  	if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_NOTREADY) {
  		kprintf("in6_ifadd: link-local address not ready\n");
  		return NULL;
  	}
  #endif
  
  	/* prefixlen + ifidlen must be equal to 128 */
  	plen0 = in6_mask2len(&ib->ia_prefixmask.sin6_addr, NULL);
  	if (prefixlen != plen0) {
  		nd6log((LOG_INFO, "in6_ifadd: wrong prefixlen for %s "
  		    "(prefix=%d ifid=%d)\n",
  		    if_name(ifp), prefixlen, 128 - plen0));
  		return NULL;
  	}
  
  	/* make ifaddr */
  
  	bzero(&ifra, sizeof(ifra));
  	/*
  	 * in6_update_ifa() does not use ifra_name, but we accurately set it
  	 * for safety.
  	 */
  	strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));
  	ifra.ifra_addr.sin6_family = AF_INET6;
  	ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
  	/* prefix */
  	bcopy(&pr->ndpr_prefix.sin6_addr, &ifra.ifra_addr.sin6_addr,
  	      sizeof(ifra.ifra_addr.sin6_addr));
  	ifra.ifra_addr.sin6_addr.s6_addr32[0] &= mask.s6_addr32[0];
  	ifra.ifra_addr.sin6_addr.s6_addr32[1] &= mask.s6_addr32[1];
  	ifra.ifra_addr.sin6_addr.s6_addr32[2] &= mask.s6_addr32[2];
  	ifra.ifra_addr.sin6_addr.s6_addr32[3] &= mask.s6_addr32[3];
  
  	/* interface ID */
  	if (ifid == NULL || IN6_IS_ADDR_UNSPECIFIED(ifid))
  		ifid = &ib->ia_addr.sin6_addr;
  	ifra.ifra_addr.sin6_addr.s6_addr32[0]
  		|= (ifid->s6_addr32[0] & ~mask.s6_addr32[0]);
  	ifra.ifra_addr.sin6_addr.s6_addr32[1]
  		|= (ifid->s6_addr32[1] & ~mask.s6_addr32[1]);
  	ifra.ifra_addr.sin6_addr.s6_addr32[2]
  		|= (ifid->s6_addr32[2] & ~mask.s6_addr32[2]);
  	ifra.ifra_addr.sin6_addr.s6_addr32[3]
  		|= (ifid->s6_addr32[3] & ~mask.s6_addr32[3]);
  
  	/* new prefix mask. */
  	ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
  	ifra.ifra_prefixmask.sin6_family = AF_INET6;
  	bcopy(&mask, &ifra.ifra_prefixmask.sin6_addr,
  	      sizeof(ifra.ifra_prefixmask.sin6_addr));
  
  	/*
  	 * lifetime.
  	 * XXX: in6_init_address_ltimes would override these values later.
  	 * We should reconsider this logic.
  	 */
  	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 */
  	/*
  	 * temporarily set the nopfx flag to avoid conflict.
  	 * XXX: we should reconsider the entire mechanism about prefix
  	 * manipulation.
  	 */
  	ifra.ifra_flags |= IN6_IFF_NOPFX;
  
  	/*
  	 * keep the new address, regardless of the result of in6_update_ifa.
  	 * XXX: this address is now meaningless.
  	 * We should reconsider its role.
  	 */
  	pr->ndpr_addr = ifra.ifra_addr.sin6_addr;
  
  	/* allocate ifaddr structure, link into chain, etc. */
  	if ((error = in6_update_ifa(ifp, &ifra, NULL)) != 0) {
  		nd6log((LOG_ERR,
  		    "in6_ifadd: failed to make ifaddr %s on %s (errno=%d)\n",
  		    ip6_sprintf(&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);
  
  	return (ia);		/* this must NOT be NULL. */
  }
  
  /*
   * Parameters:
   *	ia0:	corresponding public address
   */
  int
  in6_tmpifadd(const struct in6_ifaddr *ia0, int forcegen)
  {
  	struct ifnet *ifp = ia0->ia_ifa.ifa_ifp;
  	struct in6_ifaddr *newia;
  	struct in6_aliasreq ifra;
  	int i, error;
  	int trylimit = 3;	/* XXX: adhoc value */
  	u_int32_t randid[2];
  	time_t vltime0, pltime0;
  
  	bzero(&ifra, sizeof(ifra));
  	strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));
  	ifra.ifra_addr = ia0->ia_addr;
  	/* copy prefix mask */
  	ifra.ifra_prefixmask = ia0->ia_prefixmask;
  	/* clear the old IFID */
  	for (i = 0; i < 4; i++) {
  		ifra.ifra_addr.sin6_addr.s6_addr32[i]
  			&= ifra.ifra_prefixmask.sin6_addr.s6_addr32[i];
  	}
  
  again:
  	in6_get_tmpifid(ifp, (u_int8_t *)randid,
  			(const u_int8_t *)&ia0->ia_addr.sin6_addr.s6_addr[8],
  			forcegen);
  	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]));
  
  	/*
  	 * If by chance the new temporary address is the same as an address
  	 * already assigned to the interface, generate a new randomized
  	 * interface identifier and repeat this step.
  	 * RFC 3041 3.3 (4).
  	 */
  	if (in6ifa_ifpwithaddr(ifp, &ifra.ifra_addr.sin6_addr) != NULL) {
  		if (trylimit-- == 0) {
  			nd6log((LOG_NOTICE, "in6_tmpifadd: failed to find "
  			    "a unique random IFID\n"));
  			return (EEXIST);
  		}
  		forcegen = 1;
  		goto again;
  	}
  
  	/*
  	 * 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_expire != 0) {
  		vltime0 = IFA6_IS_INVALID(ia0) ? 0 :
  			(ia0->ia6_lifetime.ia6t_expire - time_second);
  		if (vltime0 > ip6_temp_valid_lifetime)
  			vltime0 = ip6_temp_valid_lifetime;
  	} else
  		vltime0 = ip6_temp_valid_lifetime;
  	if (ia0->ia6_lifetime.ia6t_preferred != 0) {
  		pltime0 = IFA6_IS_DEPRECATED(ia0) ? 0 :
  			(ia0->ia6_lifetime.ia6t_preferred - time_second);
  		if (pltime0 > ip6_temp_preferred_lifetime - ip6_desync_factor) {
  			pltime0 = ip6_temp_preferred_lifetime -
  				ip6_desync_factor;
  		}
  	} else
  		pltime0 = ip6_temp_preferred_lifetime - 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 <= 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. */
  	if ((error = in6_update_ifa(ifp, &ifra, NULL)) != 0)
  		return (error);
  
  	newia = in6ifa_ifpwithaddr(ifp, &ifra.ifra_addr.sin6_addr);
  	if (newia == NULL) {	/* XXX: can it happen? */
  		nd6log((LOG_ERR,
  		    "in6_tmpifadd: ifa update succeeded, but we got "
  		    "no ifaddr\n"));
  		return (EINVAL); /* XXX */
  	}
  	newia->ia6_ndpr = ia0->ia6_ndpr;
  	newia->ia6_ndpr->ndpr_refcnt++;
  
  	return (0);
  }
  
  int
  in6_init_prefix_ltimes(struct nd_prefix *ndpr)
  {
  	/* check if preferred lifetime > valid lifetime.  RFC2462 5.5.3 (c) */
  	if (ndpr->ndpr_pltime > ndpr->ndpr_vltime) {
  		nd6log((LOG_INFO, "in6_init_prefix_ltimes: preferred lifetime"
  		    "(%d) is greater than valid lifetime(%d)\n",
  		    (u_int)ndpr->ndpr_pltime, (u_int)ndpr->ndpr_vltime));
  		return (EINVAL);
  	}
  	if (ndpr->ndpr_pltime == ND6_INFINITE_LIFETIME)
  		ndpr->ndpr_preferred = 0;
  	else
  		ndpr->ndpr_preferred = time_second + ndpr->ndpr_pltime;
  	if (ndpr->ndpr_vltime == ND6_INFINITE_LIFETIME)
  		ndpr->ndpr_expire = 0;
  	else
  		ndpr->ndpr_expire = time_second + 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_second;
  		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_second;
  		lt6->ia6t_preferred += lt6->ia6t_pltime;
  	}
  }
  
  /*
   * 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)
  {
  	struct radix_node_head *rnh = rt_tables[mycpuid][AF_INET6];
  
  	/* We'll care only link-local addresses */
  	if (!IN6_IS_ADDR_LINKLOCAL(gateway))
  		return;
  	/* XXX: hack for KAME's link-local address kludge */
  	gateway->s6_addr16[1] = htons(ifp->if_index);
  
  	rnh->rnh_walktree(rnh, rt6_deleteroute, (void *)gateway);
  }
  
  static int
  rt6_deleteroute(struct radix_node *rn, void *arg)
  {
  #define SIN6(s)	((struct sockaddr_in6 *)s)
  	struct rtentry *rt = (struct rtentry *)rn;
  	struct in6_addr *gate = (struct in6_addr *)arg;
  
  	if (rt->rt_gateway == NULL || rt->rt_gateway->sa_family != AF_INET6)
  		return (0);
  
  	if (!IN6_ARE_ADDR_EQUAL(gate, &SIN6(rt->rt_gateway)->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?
  	 */
  	if (rt->rt_flags & RTF_STATIC)
  		return (0);
  
  	/*
  	 * We delete only host route. This means, in particular, we don't
  	 * delete default route.
  	 */
  	if (!(rt->rt_flags & RTF_HOST))
  		return (0);
  
  	return (rtrequest(RTM_DELETE, rt_key(rt),
  			 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0));
  #undef SIN6
  }
  
  int
  nd6_setdefaultiface(int ifindex)
  {
  	int error = 0;
  
  	if (ifindex < 0 || if_index < ifindex)
  		return (EINVAL);
  
  	if (nd6_defifindex != ifindex) {
  		nd6_defifindex = ifindex;
  		if (nd6_defifindex > 0)
  			nd6_defifp = ifindex2ifnet[nd6_defifindex];
  		else
  			nd6_defifp = NULL;
  
  		/*
  		 * If the Default Router List is empty, install a route
  		 * to the specified interface as default or remove the default
  		 * route when the default interface becomes canceled.
  		 * The check for the queue is actually redundant, but
  		 * we do this here to avoid re-install the default route
  		 * if the list is NOT empty.
  		 */
  		if (TAILQ_FIRST(&nd_defrouter) == NULL)
  			defrouter_select();
  
  		/*
  		 * Our current implementation assumes one-to-one maping between
  		 * interfaces and links, so it would be natural to use the
  		 * default interface as the default link.
  		 */
  		scope6_setdefault(nd6_defifp);
  	}
  
  	return (error);
  }
  