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nd6_rtr.c

//==========================================================================
//
//      src/sys/netinet6/nd6_rtr.c
//
//==========================================================================
//####BSDCOPYRIGHTBEGIN####
//
// -------------------------------------------
//
// Portions of this software may have been derived from OpenBSD, 
// FreeBSD or other sources, and are covered by the appropriate
// copyright disclaimers included herein.
//
// Portions created by Red Hat are
// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
//
// -------------------------------------------
//
//####BSDCOPYRIGHTEND####
//==========================================================================

/*    $KAME: nd6_rtr.c,v 1.187 2001/12/18 02:01:25 itojun Exp $   */

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

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <sys/queue.h>
#ifdef __OpenBSD__
#include <dev/rndvar.h>
#endif

#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>

#ifdef MIP6
#include <netinet6/mip6.h>
#endif /* MIP6 */

#define SDL(s)    ((struct sockaddr_dl *)s)

static int rtpref __P((struct nd_defrouter *));
static struct nd_defrouter *defrtrlist_update __P((struct nd_defrouter *));
static struct in6_ifaddr *in6_ifadd __P((struct nd_prefix *));
static struct nd_pfxrouter *pfxrtr_lookup __P((struct nd_prefix *,
      struct nd_defrouter *));
static void pfxrtr_add __P((struct nd_prefix *, struct nd_defrouter *));
static void pfxrtr_del __P((struct nd_pfxrouter *));
static struct nd_pfxrouter *find_pfxlist_reachable_router
      __P((struct nd_prefix *));
static void defrouter_delreq __P((struct nd_defrouter *));
static void defrouter_addifreq __P((struct ifnet *));
static void defrouter_delifreq __P((void));
static void nd6_rtmsg __P((int, struct rtentry *));

static void in6_init_address_ltimes __P((struct nd_prefix *ndpr,
                               struct in6_addrlifetime *lt6));

static int rt6_deleteroute __P((struct radix_node *, void *));

extern int nd6_recalc_reachtm_interval;

static struct ifnet *nd6_defifp;
int nd6_defifindex;
static struct ifaddr *nd6_defif_installed = NULL;

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;
int ip6_temp_regen_advance = TEMPADDR_REGEN_ADVANCE;

/* RTPREF_MEDIUM has to be 0! */
#define RTPREF_HIGH     1
#define RTPREF_MEDIUM   0
#define RTPREF_LOW      (-1)
#define RTPREF_INVALID  (-2)

/*
 * 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(m, off, icmp6len)
      struct      mbuf *m;
      int off, 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 = (struct sockaddr_dl *)NULL;
      struct llinfo_nd6 *ln = (struct llinfo_nd6 *)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(m, off, icmp6len)
      struct      mbuf *m;
      int off, icmp6len;
{
      struct ifnet *ifp = m->m_pkthdr.rcvif;
      struct nd_ifinfo *ndi = &nd_ifinfo[ifp->if_index];
      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 (!(nd_ifinfo[ifp->if_index].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;
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
      long time_second = time.tv_sec;
#endif

      Bzero(&dr0, sizeof(dr0));
      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) {
            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;
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
            long time_second = time.tv_sec;
#endif

            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;
#ifdef MIP6
                  pr.ndpr_raf_router = (pi->nd_opt_pi_flags_reserved &
                                    ND_OPT_PI_FLAG_ROUTER) ? 1 : 0;
#endif /* MIP6 */
                  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);
                  pr.ndpr_lastupdate = time_second;

                  if (in6_init_prefix_ltimes(&pr))
                        continue; /* prefix lifetime init failed */
#ifdef MIP6
                  if (MIP6_IS_MN) {
                        if (mip6_prefix_list_update(&saddr6, &pr, dr, m)) {
                              mip6log((LOG_ERR,
                                     "%s:%d: "
                                     "prefix info processing "
                                     "failed\n",
                                     __FILE__, __LINE__));
                              goto freeit;
                        }
                  }
#endif /* MIP6 */
                  (void)prelist_update(&pr, dr, m);
            }
      }

#ifdef MIP6
      if (MIP6_IS_MN) {
            /* check reachability of all routers. */
            mip6_probe_routers();
      }

      /* update home agent list. */
      if ((MIP6_IS_MN || MIP6_IS_HA)
          && dr
          && (dr->flags & ND_RA_FLAG_HOME_AGENT)) {
            if (mip6_ha_list_update_hainfo(&mip6_ha_list,
                                     dr, ndopts.nd_opts_hai)) {
                  mip6log((LOG_ERR,
                         "%s:%d: global HA list update failed\n",
                         __FILE__, __LINE__));
            }
      }
      if (dr == NULL) {
            struct mip6_ha *mha;

            /* the home agent is shutting down. */
            mha = mip6_ha_list_find_withaddr(&mip6_ha_list, &saddr6);
            if (mha) {
                  if (mip6_ha_list_remove(&mip6_ha_list, mha)) {
                        mip6log((LOG_ERR,
                               "%s:%d: HA entry remove failed.\n",
                               __FILE__, __LINE__));
                  }
            }
      }
#endif /* MIP6 */

      /*
       * 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
 */

/* tell the change to user processes watching the routing socket. */
static void
nd6_rtmsg(cmd, rt)
      int cmd;
      struct rtentry *rt;
{
      struct rt_addrinfo info;

      bzero((caddr_t)&info, sizeof(info));
#if (defined(__bsdi__) && _BSDI_VERSION >= 199802) /* BSDI4 */
      /* maybe this is unnecessary */
      info.rti_flags = rt->rt_flags;
#endif
      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 defined(__bsdi__) || (defined(__FreeBSD__) && __FreeBSD__ < 3)
      info.rti_info[RTAX_IFP] = rt->rt_ifp->if_addrlist->ifa_addr;
#else
      info.rti_info[RTAX_IFP] =
            (struct sockaddr *)TAILQ_FIRST(&rt->rt_ifp->if_addrlist);
#endif
      info.rti_info[RTAX_IFA] = rt->rt_ifa->ifa_addr;

      rt_missmsg(cmd, &info, rt->rt_flags, 0);
}

void
defrouter_addreq(new)
      struct nd_defrouter *new;
{
      struct sockaddr_in6 def, mask, gate;
      struct rtentry *newrt = NULL;
      int s;
      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 = mask.sin6_family = gate.sin6_family = AF_INET6;
      gate.sin6_addr = new->rtaddr;

#ifdef __NetBSD__
      s = splsoftnet();
#else
      s = splnet();
#endif
      error = rtrequest(RTM_ADD, (struct sockaddr *)&def,
            (struct sockaddr *)&gate, (struct sockaddr *)&mask,
            RTF_GATEWAY, &newrt);
      if (newrt) {
            nd6_rtmsg(RTM_ADD, newrt); /* tell user process */
            newrt->rt_refcnt--;
      }
      if (error == 0)
            new->installed = 1;
      splx(s);
      return;
}

/* Add a route to a given interface as default */
static void
defrouter_addifreq(ifp)
      struct ifnet *ifp;
{
      struct sockaddr_in6 def, mask;
      struct ifaddr *ifa;
      struct rtentry *newrt = NULL;
      int error, flags;
#if (defined(__bsdi__) && _BSDI_VERSION >= 199802)
      struct rt_addrinfo info;
#endif

      /* remove one if we have already installed one */
      if (nd6_defif_installed)
            defrouter_delifreq();

      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;
#if (defined(__bsdi__) && _BSDI_VERSION >= 199802)
      bzero(&info, sizeof(info));
      info.rti_info[RTAX_DST] = (struct sockaddr *)&def;
      info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)ifa->ifa_addr;
      info.rti_info[RTAX_NETMASK] = (struct sockaddr *)&mask;
      info.rti_info[RTAX_IFA] = (struct sockaddr *)ifa->ifa_addr;
      info.rti_flags = flags;
      error = rtrequest1(RTM_ADD, &info, &newrt);
#else
      error = rtrequest(RTM_ADD, (struct sockaddr *)&def, ifa->ifa_addr,
                    (struct sockaddr *)&mask, flags, &newrt);
#endif
      if (error != 0) {
            nd6log((LOG_ERR,
                "defrouter_addifreq: failed to install a route to "
                "interface %s (errno = %d)\n",
                if_name(ifp), error));

            if (newrt)  /* maybe unnecessary, but do it for safety */
                  newrt->rt_refcnt--;
      } else {
            if (newrt) {
                  nd6_rtmsg(RTM_ADD, newrt);
                  newrt->rt_refcnt--;
            }
      }

      nd6_defif_installed = ifa;
      IFAREF(ifa);
}

/* Remove a default route points to interface */
static void
defrouter_delifreq()
{
      struct sockaddr_in6 def, mask;
      struct rtentry *oldrt = NULL;

      if (!nd6_defif_installed)
            return;

      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;

      rtrequest(RTM_DELETE, (struct sockaddr *)&def,
          (struct sockaddr *)nd6_defif_installed->ifa_addr,
          (struct sockaddr *)&mask, RTF_GATEWAY, &oldrt);
      if (oldrt) {
            nd6_rtmsg(RTM_DELETE, oldrt);
            if (oldrt->rt_refcnt <= 0) {
                  /*
                   * XXX: borrowed from the RTM_DELETE case of
                   * rtrequest().
                   */
                  oldrt->rt_refcnt++;
                  rtfree(oldrt);
            }
      }

      IFAFREE(nd6_defif_installed);
      nd6_defif_installed = NULL;
}

struct nd_defrouter *
defrouter_lookup(addr, ifp)
      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
defrtrlist_del(dr)
      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->installed) {
            deldr = dr;
            defrouter_delreq(dr);
      }
      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();

      free(dr, M_IP6NDP);
}

/*
 * Remove the default route for a given router.
 * This is just a subroutine function for defrouter_select(), and should
 * not be called from anywhere else.
 */
static void
defrouter_delreq(dr)
      struct nd_defrouter *dr;
{
      struct sockaddr_in6 def, mask, gw;
      struct rtentry *oldrt = NULL;

      Bzero(&def, sizeof(def));
      Bzero(&mask, sizeof(mask));
      Bzero(&gw, sizeof(gw));

      def.sin6_len = mask.sin6_len = gw.sin6_len =
          sizeof(struct sockaddr_in6);
      def.sin6_family = mask.sin6_family = gw.sin6_family = AF_INET6;
      if (dr)
            gw.sin6_addr = dr->rtaddr;

      rtrequest(RTM_DELETE, (struct sockaddr *)&def,
          dr ? (struct sockaddr *)&gw : NULL,
          (struct sockaddr *)&mask, RTF_GATEWAY, &oldrt);
      if (oldrt) {
            nd6_rtmsg(RTM_DELETE, oldrt);
            if (oldrt->rt_refcnt <= 0) {
                  /*
                   * XXX: borrowed from the RTM_DELETE case of
                   * rtrequest().
                   */
                  oldrt->rt_refcnt++;
                  rtfree(oldrt);
            }
      }

      if (dr)
            dr->installed = 0;
}

/*
 * remove all default routes from default router list
 */
void
defrouter_reset()
{
      struct nd_defrouter *dr;

      for (dr = TAILQ_FIRST(&nd_defrouter); dr;
           dr = TAILQ_NEXT(dr, dr_entry))
            defrouter_delreq(dr);
      defrouter_delifreq();

      /*
       * XXX should we also nuke any default routers in the kernel, by 
       * going through them by rtalloc1()?
       */
}

/*
 * 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.
 */
void
defrouter_select()
{
#ifdef __NetBSD__
      int s = splsoftnet();
#else
      int s = splnet();
#endif
      struct nd_defrouter *dr, *selected_dr = NULL, *installed_dr = NULL;
      struct rtentry *rt = NULL;
      struct llinfo_nd6 *ln = NULL;

      /*
       * This function should be called only when acting as an autoconfigured
       * host.  Although the remaining part of this function is not effective
       * if the node is not an autoconfigured host, we explicitly exclude
       * such cases here for safety.
       */
      if (ip6_forwarding || !ip6_accept_rtadv) {
            nd6log((LOG_WARNING,
                "defrouter_select: called unexpectedly (forwarding=%d, "
                "accept_rtadv=%d)\n", ip6_forwarding, ip6_accept_rtadv));
            splx(s);
            return;
      }

      /*
       * Let's handle easy case (3) first:
       * If default router list is empty, we should probably install
       * an interface route and assume that all destinations are on-link.
       */
      if (!TAILQ_FIRST(&nd_defrouter)) {
            /*
             * XXX: The specification does not say this mechanism should
             * be restricted to hosts, but this would be not useful
             * (even harmful) for routers.
             * This test is meaningless due to a test at the beginning of
             * the function, but we intentionally keep it to make the note
             * clear.
             */
            if (!ip6_forwarding) {
                  if (nd6_defifp) {
                        /*
                         * Install a route to the default interface
                         * as default route.
                         */
                        defrouter_addifreq(nd6_defifp);
                  } else {
                        /*
                         * purge the existing route.
                         * XXX: is this really correct?
                         */
                        defrouter_delifreq();
                        nd6log((LOG_INFO, "defrouter_select: "
                            "there's no default router and no default"
                            " interface\n"));
                  }
            }
            splx(s);
            return;
      }

      /*
       * If we have a default route for the default interface, delete it.
       * Note that the existence of the route is checked in the delete
       * function.
       */
      defrouter_delifreq();

      /*
       * 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().
       */
      for (dr = TAILQ_FIRST(&nd_defrouter); dr;
           dr = TAILQ_NEXT(dr, dr_entry)) {
            if (!selected_dr &&
                (rt = nd6_lookup(&dr->rtaddr, 0, dr->ifp)) &&
                (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
                ND6_IS_LLINFO_PROBREACH(ln)) {
                  selected_dr = dr;
            }

            if (dr->installed && !installed_dr)
                  installed_dr = dr;
            else if (dr->installed && installed_dr) {
                  /* this should not happen.  warn for diagnosis. */
                  log(LOG_ERR, "defrouter_select: 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) {
            if (!installed_dr || !TAILQ_NEXT(installed_dr, dr_entry))
                  selected_dr = TAILQ_FIRST(&nd_defrouter);
            else
                  selected_dr = TAILQ_NEXT(installed_dr, dr_entry);
      } else if (installed_dr &&
               (rt = nd6_lookup(&installed_dr->rtaddr, 0,
                            installed_dr->ifp)) &&
               (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
               ND6_IS_LLINFO_PROBREACH(ln) &&
               rtpref(selected_dr) <= rtpref(installed_dr)) {
                  selected_dr = installed_dr;
      }

      /*
       * If the selected router is different than the installed one,
       * remove the installed router and install the selected one.
       * Note that the selected router is never NULL here.
       */
      if (installed_dr != selected_dr) {
            if (installed_dr)
                  defrouter_delreq(installed_dr);
            defrouter_addreq(selected_dr);
      }

      splx(s);
      return;
}

/* 
 * for default router selection
 * regards router-preference field as a 2-bit signed integer 
 */
static int
rtpref(struct nd_defrouter *dr)
{
#ifdef RTPREF
      switch (dr->flags & 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", dr->flags);
            return RTPREF_INVALID;
      }
      /* NOT REACH HERE */
#else
      return RTPREF_MEDIUM;
#endif
}

static struct nd_defrouter *
defrtrlist_update(new)
      struct nd_defrouter *new;
{
      struct nd_defrouter *dr, *n;
#ifdef __NetBSD__
      int s = splsoftnet();
#else
      int s = splnet();
#endif

      if ((dr = defrouter_lookup(&new->rtaddr, new->ifp)) != NULL) {
            /* entry exists */
            if (new->rtlifetime == 0) {
                  defrtrlist_del(dr);
                  dr = NULL;
            } else {
                  int oldpref = rtpref(dr);

                  /* override */
                  dr->flags = new->flags; /* 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.
                   */
                  if (rtpref(new) == oldpref) {
                        splx(s);
                        return(dr);
                  }

                  /*
                   * preferred router may be changed, so relocate
                   * this router.
                   * XXX: calling TAILQ_REMOVE directly is a bad manner.
                   * However, since defrtrlist_del() has many side
                   * effects, we intentionally do so here.
                   * defrouter_select() below will handle routing
                   * changes later.
                   */
                  TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
                  n = dr;
                  goto insert;
            }
            splx(s);
            return(dr);
      }

      /* entry does not exist */
      if (new->rtlifetime == 0) {
            splx(s);
            return(NULL);
      }

      n = (struct nd_defrouter *)malloc(sizeof(*n), M_IP6NDP, M_NOWAIT);
      if (n == NULL) {
            splx(s);
            return(NULL);
      }
      bzero(n, sizeof(*n));
      *n = *new;

insert:
      /*
       * 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 */
      for (dr = TAILQ_FIRST(&nd_defrouter); dr;
           dr = TAILQ_NEXT(dr, dr_entry)) {
            if (rtpref(n) > rtpref(dr))
                  break;
      }
      if (dr)
            TAILQ_INSERT_BEFORE(dr, n, dr_entry);
      else
            TAILQ_INSERT_TAIL(&nd_defrouter, n, dr_entry);

      defrouter_select();

      splx(s);
            
      return(n);
}

static struct nd_pfxrouter *
pfxrtr_lookup(pr, dr)
      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(pr, dr)
      struct nd_prefix *pr;
      struct nd_defrouter *dr;
{
      struct nd_pfxrouter *new;

      new = (struct nd_pfxrouter *)malloc(sizeof(*new), M_IP6NDP, M_NOWAIT);
      if (new == NULL)
            return;
      bzero(new, sizeof(*new));
      new->router = dr;

      LIST_INSERT_HEAD(&pr->ndpr_advrtrs, new, pfr_entry);

      pfxlist_onlink_check();
}

static void
pfxrtr_del(pfr)
      struct nd_pfxrouter *pfr;
{
      LIST_REMOVE(pfr, pfr_entry);
      free(pfr, M_IP6NDP);
}

struct nd_prefix *
nd6_prefix_lookup(pr)
      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(pr, dr, newp)
      struct nd_prefix *pr, **newp;
      struct nd_defrouter *dr;
{
      struct nd_prefix *new = NULL;
      int i, s;

      new = (struct nd_prefix *)malloc(sizeof(*new), M_IP6NDP, M_NOWAIT);
      if (new == NULL)
            return ENOMEM;
      bzero(new, sizeof(*new));
      *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];

#ifdef __NetBSD__
      s = splsoftnet();
#else
      s = splnet();
#endif
      /* link ndpr_entry to nd_prefix list */
      LIST_INSERT_HEAD(&nd_prefix, new, ndpr_entry);
      splx(s);

      /* 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(pr)
      struct nd_prefix *pr;
{
      struct nd_pfxrouter *pfr, *next;
      int e, s;

      /* 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) != 0 &&
          (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? */

#ifdef __NetBSD__
      s = splsoftnet();
#else
      s = splnet();
#endif

      /* 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;

            free(pfr, M_IP6NDP);
      }
      splx(s);

      free(pr, M_IP6NDP);

      pfxlist_onlink_check();
}

int
prelist_update(new, dr, m)
      struct nd_prefix *new;
      struct nd_defrouter *dr; /* may be NULL */
      struct mbuf *m;
{
      struct in6_ifaddr *ia6 = NULL, *ia6_match = NULL;
      struct ifaddr *ifa;
      struct ifnet *ifp = new->ndpr_ifp;
      struct nd_prefix *pr;
#ifdef __NetBSD__
      int s = splsoftnet();
#else
      int s = splnet();
#endif
      int error = 0;
      int newprefix = 0;
      int auth;
      struct in6_addrlifetime lt6_tmp;

      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) ? 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;
                  pr->ndpr_lastupdate = new->ndpr_lastupdate;
            }

            if (new->ndpr_raf_onlink &&
                (pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
                  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;

            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 sure 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 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.
       * 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.
       */
#if defined(__bsdi__) || (defined(__FreeBSD__) && __FreeBSD__ < 3)
      for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
#elif defined(__FreeBSD__) && __FreeBSD__ >= 4
      TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
#else
      for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = ifa->ifa_list.tqe_next)
#endif
      {
            struct in6_ifaddr *ifa6;
            int ifa_plen;
            u_int32_t storedlifetime;
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
            long time_second = time.tv_sec;
#endif

            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) != 0)
                  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) == 0)
                  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)
            /*
             * RFC2462 introduces the notion of StoredLifetime to the
             * "two hours" rule as follows:
             *   the Lifetime associated with the previously autoconfigured
             *   address.
             * Our interpretation of this definition is "the remaining
             * lifetime to expiration at the evaluation time".  One might
             * be wondering if this interpretation is really conform to the
             * RFC, because the text can read that "Lifetimes" are never
             * decreased, and our definition of the "storedlifetime" below
             * essentially reduces the "Valid Lifetime" advertised in the
             * previous RA.  But, this is due to the wording of the text,
             * and our interpretation is the same as an author's intention.
             * See the discussion in the IETF ipngwg ML in August 2001,
             * with the Subject "StoredLifetime in RFC 2462".
             */
            lt6_tmp = ifa6->ia6_lifetime;
            if (lt6_tmp.ia6t_vltime == ND6_INFINITE_LIFETIME)
                  storedlifetime = ND6_INFINITE_LIFETIME;
            else if (time_second - ifa6->ia6_updatetime >
                   lt6_tmp.ia6t_vltime) {
                  /*
                   * The case of "invalid" address.  We should usually
                   * not see this case.
                   */
                  storedlifetime = 0;
            } else
                  storedlifetime = lt6_tmp.ia6t_vltime -
                        (time_second - ifa6->ia6_updatetime);
            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);

            /*
             * We need to treat lifetimes for temporary addresses
             * differently, according to
             * draft-ietf-ipngwg-temp-addresses-v2-00.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 (ip6_temp_valid_lifetime >
                      (u_int32_t)(time_second - ifa6->ia6_createtime)) {
                        maxvltime = ip6_temp_valid_lifetime -
                              (time_second - ifa6->ia6_createtime);
                  } else
                        maxvltime = 0;
                  if (ip6_temp_preferred_lifetime >
                      (u_int32_t)((time_second - ifa6->ia6_createtime) +
                              ip6_desync_factor)) {
                        maxpltime = ip6_temp_preferred_lifetime -
                              (time_second - ifa6->ia6_createtime) -
                              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_second;
      }
      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) {
                  /*
                   * note that we should use pr (not new) for reference.
                   */
                  pr->ndpr_refcnt++;
                  ia6->ia6_ndpr = pr;

                  /*
                   * draft-ietf-ipngwg-temp-addresses-v2-00 3.3 (2).
                   * When a new public address is created as described
                   * in RFC2462, also create a new temporary address.
                   *
                   * draft-ietf-ipngwg-temp-addresses-v2-00 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. */
            }
      }

 end:
      splx(s);
      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(pr)
      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()
{
      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 != NULL || TAILQ_FIRST(&nd_defrouter) != 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.
             */
            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) == 0 &&
                      find_pfxlist_reachable_router(pr) == NULL)
                        pr->ndpr_stateflags |= NDPRF_DETACHED;
                  if ((pr->ndpr_stateflags & NDPRF_DETACHED) != 0 &&
                      find_pfxlist_reachable_router(pr) != 0)
                        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) != 0)
                        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) != 0 &&
                (pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
                  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) == 0 &&
                (pr->ndpr_stateflags & NDPRF_ONLINK) == 0 &&
                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) == 0)
                        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) == 0)
                        continue;

                  ifa->ia6_flags &= ~IN6_IFF_DETACHED;
            }
      }

#ifdef MIP6
      if (MIP6_IS_MN) {
            int coa_changed = 0;

            hif_save_location();
            coa_changed = mip6_select_coa2();
            (void)mip6_process_pfxlist_status_change(&hif_coa);
            if (coa_changed == 1)
                  mip6_process_movement();
            else
                  hif_restore_location();
      }
#endif /* MIP6 */
}

int
nd6_prefix_onlink(pr)
      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;
      struct rtentry *rt = NULL;

      /* sanity check */
      if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
            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) == 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))
                  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) {
            /* XXX: freebsd does not have ifa_ifwithaf */
#if defined(__bsdi__) || (defined(__FreeBSD__) && __FreeBSD__ < 3)
            for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
#elif defined(__FreeBSD__) && __FreeBSD__ >= 4
            TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
#else
            for (ifa = ifp->if_addrlist.tqh_first;
                 ifa;
                 ifa = ifa->ifa_list.tqe_next)
#endif
            {
                  if (ifa->ifa_addr->sa_family == AF_INET6)
                        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;
      /* rtrequest() will probably set RTF_UP, but we're not sure. */
      rtflags = ifa->ifa_flags | 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(RTM_ADD, (struct sockaddr *)&pr->ndpr_prefix,
                    ifa->ifa_addr, (struct sockaddr *)&mask6,
                    rtflags, &rt);
      if (error == 0) {
            if (rt != NULL) /* this should be non NULL, though */
                  nd6_rtmsg(RTM_ADD, rt);
            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));
      }

      if (rt != NULL)
            rt->rt_refcnt--;

      return(error);
}

int
nd6_prefix_offlink(pr)
      struct nd_prefix *pr;
{
      int error = 0;
      struct ifnet *ifp = pr->ndpr_ifp;
      struct nd_prefix *opr;
      struct sockaddr_in6 sa6, mask6;
      struct rtentry *rt = NULL;

      /* sanity check */
      if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
            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(RTM_DELETE, (struct sockaddr *)&sa6, NULL,
                    (struct sockaddr *)&mask6, 0, &rt);
      if (error == 0) {
            pr->ndpr_stateflags &= ~NDPRF_ONLINK;

            /* report the route deletion to the routing socket. */
            if (rt != NULL)
                  nd6_rtmsg(RTM_DELETE, rt);

            /*
             * 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) != 0)
                        continue;

                  /*
                   * KAME specific: detached prefixes should not be
                   * on-link.
                   */
                  if ((opr->ndpr_stateflags & 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;

                        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));
      }

      if (rt != NULL) {
            if (rt->rt_refcnt <= 0) {
                  /* XXX: we should free the entry ourselves. */
                  rt->rt_refcnt++;
                  rtfree(rt);
            }
      }

      return(error);
}

static struct in6_ifaddr *
in6_ifadd(pr)
      struct nd_prefix *pr;
{
      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_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 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.
       */
      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) {
            printf("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 */
      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]);
          
      /* 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 */

      /* 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 is always non-NULL */
}

int
in6_tmpifadd(ia0, forcegen)
      const struct in6_ifaddr *ia0; /* corresponding public address */
      int forcegen;
{
      struct ifnet *ifp = ia0->ia_ifa.ifa_ifp;
      struct in6_ifaddr *newia, *ia;
      struct in6_aliasreq ifra;
      int i, error;
      int trylimit = 3; /* XXX: adhoc value */
      u_int32_t randid[2];
      u_int32_t vltime0, pltime0;
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
      time_t time_second = (time_t)time.tv_sec;
#endif

      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:
      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, "in6_tmpifadd: failed to find a good "
                  "random IFID\n"));
            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.
       */
      for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
            if (SA6_ARE_ADDR_EQUAL(&ia->ia_addr,
                               &ifra.ifra_addr)) {
                  if (trylimit-- == 0) {
                        /*
                         * Give up.  Something strange should have
                         * happened.
                         */
                        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_vltime != ND6_INFINITE_LIFETIME) {
            vltime0 = IFA6_IS_INVALID(ia0) ? 0 :
                  (ia0->ia6_lifetime.ia6t_vltime -
                   (time_second - ia0->ia6_updatetime));
            if (vltime0 > ip6_temp_valid_lifetime)
                  vltime0 = ip6_temp_valid_lifetime;
      } else
            vltime0 = 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_second - ia0->ia6_updatetime));
            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++;

      /*
       * 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);
}         

int
in6_init_prefix_ltimes(struct nd_prefix *ndpr)
{
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
      long time_second = time.tv_sec;
#endif

      /* 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)
{
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
      long time_second = time.tv_sec;
#endif

      /* Valid lifetime must not be updated unless explicitly specified. */
      /* 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(gateway, ifp)
      struct in6_addr *gateway;
      struct ifnet *ifp;
{
      struct radix_node_head *rnh = rt_tables[AF_INET6];
#ifdef __NetBSD__
      int s = splsoftnet();
#else
      int s = splnet();
#endif

      /* We'll care only link-local addresses */
      if (!IN6_IS_ADDR_LINKLOCAL(gateway)) {
            splx(s);
            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);
      splx(s);
}

static int
rt6_deleteroute(rn, arg)
      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) != 0)
            return(0);

      /*
       * We delete only host route. This means, in particular, we don't
       * delete default route.
       */
      if ((rt->rt_flags & RTF_HOST) == 0)
            return(0);

      return(rtrequest(RTM_DELETE, rt_key(rt),
                   rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0));
#undef SIN6
}

int
nd6_setdefaultiface(ifindex)
      int ifindex;
{
      int error = 0;

      if (ifindex < 0 || if_index < ifindex)
            return(EINVAL);

      if (nd6_defifindex != ifindex) {
            nd6_defifindex = ifindex;
            if (nd6_defifindex > 0) {
#if defined(__FreeBSD__) && __FreeBSD__ >= 5
                  nd6_defifp = ifnet_byindex[nd6_defifindex];
#else
                  nd6_defifp = ifindex2ifnet[nd6_defifindex];
#endif
            } else
                  nd6_defifp = NULL;

            /*
             * Rescan default router list, refresh default route(s).
             */
            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);
}

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