FreeBSD/Linux Kernel Cross Reference
sys/netinet6/in6.c

     /*      $FreeBSD$       */
     /*      $KAME: in6.c,v 1.259 2002/01/21 11:37:50 keiichi 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.
     */
    
    /*
     * Copyright (c) 1982, 1986, 1991, 1993
     *      The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
     *
     *      @(#)in.c        8.2 (Berkeley) 11/15/93
     */
    
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/errno.h>
    #include <sys/malloc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sockio.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/time.h>
    #include <sys/kernel.h>
    #include <sys/syslog.h>
    
    #include <net/if.h>
    #include <net/if_types.h>
    #include <net/route.h>
    #include <net/if_dl.h>
    
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <netinet/if_ether.h>
    #ifndef SCOPEDROUTING
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/in_pcb.h>
    #endif
    
    #include <netinet/ip6.h>
    #include <netinet6/ip6_var.h>
    #include <netinet6/nd6.h>
   #include <netinet6/mld6_var.h>
   #include <netinet6/ip6_mroute.h>
   #include <netinet6/in6_ifattach.h>
   #include <netinet6/scope6_var.h>
   #ifndef SCOPEDROUTING
   #include <netinet6/in6_pcb.h>
   #endif
   
   #include <net/net_osdep.h>
   
   MALLOC_DEFINE(M_IPMADDR, "in6_multi", "internet multicast address");
   
   /*
    * Definitions of some costant IP6 addresses.
    */
   const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
   const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
   const struct in6_addr in6addr_nodelocal_allnodes =
           IN6ADDR_NODELOCAL_ALLNODES_INIT;
   const struct in6_addr in6addr_linklocal_allnodes =
           IN6ADDR_LINKLOCAL_ALLNODES_INIT;
   const struct in6_addr in6addr_linklocal_allrouters =
           IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
   
   const struct in6_addr in6mask0 = IN6MASK0;
   const struct in6_addr in6mask32 = IN6MASK32;
   const struct in6_addr in6mask64 = IN6MASK64;
   const struct in6_addr in6mask96 = IN6MASK96;
   const struct in6_addr in6mask128 = IN6MASK128;
   
   const struct sockaddr_in6 sa6_any = {sizeof(sa6_any), AF_INET6,
                                        0, 0, IN6ADDR_ANY_INIT, 0};
   
   static int in6_lifaddr_ioctl __P((struct socket *, u_long, caddr_t,
           struct ifnet *, struct proc *));
   static int in6_ifinit __P((struct ifnet *, struct in6_ifaddr *,
                              struct sockaddr_in6 *, int));
   static void in6_unlink_ifa __P((struct in6_ifaddr *, struct ifnet *));
   
   struct in6_multihead in6_multihead;     /* XXX BSS initialization */
   
   int     (*faithprefix_p)(struct in6_addr *);
   
   /*
    * Subroutine for in6_ifaddloop() and in6_ifremloop().
    * This routine does actual work.
    */
   static void
   in6_ifloop_request(int cmd, struct ifaddr *ifa)
   {
           struct sockaddr_in6 all1_sa;
           struct rtentry *nrt = NULL;
           int e;
           
           bzero(&all1_sa, sizeof(all1_sa));
           all1_sa.sin6_family = AF_INET6;
           all1_sa.sin6_len = sizeof(struct sockaddr_in6);
           all1_sa.sin6_addr = in6mask128;
   
           /*
            * We specify the address itself as the gateway, and set the
            * RTF_LLINFO flag, so that the corresponding host route would have
            * the flag, and thus applications that assume traditional behavior
            * would be happy.  Note that we assume the caller of the function
            * (probably implicitly) set nd6_rtrequest() to ifa->ifa_rtrequest,
            * which changes the outgoing interface to the loopback interface.
            */
           e = rtrequest(cmd, ifa->ifa_addr, ifa->ifa_addr,
                         (struct sockaddr *)&all1_sa,
                         RTF_UP|RTF_HOST|RTF_LLINFO, &nrt);
           if (e != 0) {
                   log(LOG_ERR, "in6_ifloop_request: "
                       "%s operation failed for %s (errno=%d)\n",
                       cmd == RTM_ADD ? "ADD" : "DELETE",
                       ip6_sprintf(&((struct in6_ifaddr *)ifa)->ia_addr.sin6_addr),
                       e);
           }
   
           /*
            * Make sure rt_ifa be equal to IFA, the second argument of the
            * function.
            * We need this because when we refer to rt_ifa->ia6_flags in
            * ip6_input, we assume that the rt_ifa points to the address instead
            * of the loopback address.
            */
           if (cmd == RTM_ADD && nrt && ifa != nrt->rt_ifa) {
                   IFAFREE(nrt->rt_ifa);
                   IFAREF(ifa);
                   nrt->rt_ifa = ifa;
           }
   
           /*
            * Report the addition/removal of the address to the routing socket.
            * XXX: since we called rtinit for a p2p interface with a destination,
            *      we end up reporting twice in such a case.  Should we rather
            *      omit the second report?
            */
           if (nrt) {
                   rt_newaddrmsg(cmd, ifa, e, nrt);
                   if (cmd == RTM_DELETE) {
                           if (nrt->rt_refcnt <= 0) {
                                   /* XXX: we should free the entry ourselves. */
                                   nrt->rt_refcnt++;
                                   rtfree(nrt);
                           }
                   } else {
                           /* the cmd must be RTM_ADD here */
                           nrt->rt_refcnt--;
                   }
           }
   }
   
   /*
    * Add ownaddr as loopback rtentry.  We previously add the route only if
    * necessary (ex. on a p2p link).  However, since we now manage addresses
    * separately from prefixes, we should always add the route.  We can't
    * rely on the cloning mechanism from the corresponding interface route
    * any more.
    */
   static void
   in6_ifaddloop(struct ifaddr *ifa)
   {
           struct rtentry *rt;
   
           /* If there is no loopback entry, allocate one. */
           rt = rtalloc1(ifa->ifa_addr, 0, 0);
           if (rt == NULL || (rt->rt_flags & RTF_HOST) == 0 ||
               (rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0)
                   in6_ifloop_request(RTM_ADD, ifa);
           if (rt)
                   rt->rt_refcnt--;
   }
   
   /*
    * Remove loopback rtentry of ownaddr generated by in6_ifaddloop(),
    * if it exists.
    */
   static void
   in6_ifremloop(struct ifaddr *ifa)
   {
           struct in6_ifaddr *ia;
           struct rtentry *rt;
           int ia_count = 0;
   
           /*
            * Some of BSD variants do not remove cloned routes
            * from an interface direct route, when removing the direct route
            * (see comments in net/net_osdep.h).  Even for variants that do remove
            * cloned routes, they could fail to remove the cloned routes when
            * we handle multple addresses that share a common prefix.
            * So, we should remove the route corresponding to the deleted address
            * regardless of the result of in6_is_ifloop_auto().
            */
   
           /*
            * Delete the entry only if exact one ifa exists.  More than one ifa
            * can exist if we assign a same single address to multiple
            * (probably p2p) interfaces.
            * XXX: we should avoid such a configuration in IPv6...
            */
           for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                   if (IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &ia->ia_addr.sin6_addr)) {
                           ia_count++;
                           if (ia_count > 1)
                                   break;
                   }
           }
   
           if (ia_count == 1) {
                   /*
                    * Before deleting, check if a corresponding loopbacked host
                    * route surely exists.  With this check, we can avoid to
                    * delete an interface direct route whose destination is same
                    * as the address being removed.  This can happen when remofing
                    * a subnet-router anycast address on an interface attahced
                    * to a shared medium.
                    */
                   rt = rtalloc1(ifa->ifa_addr, 0, 0);
                   if (rt != NULL && (rt->rt_flags & RTF_HOST) != 0 &&
                       (rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
                           rt->rt_refcnt--;
                           in6_ifloop_request(RTM_DELETE, ifa);
                   }
           }
   }
   
   int
   in6_ifindex2scopeid(idx)
           int idx;
   {
           struct ifnet *ifp;
           struct ifaddr *ifa;
           struct sockaddr_in6 *sin6;
   
           if (idx < 0 || if_index < idx)
                   return -1;
           ifp = ifindex2ifnet[idx];
   
           TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
           {
                   if (ifa->ifa_addr->sa_family != AF_INET6)
                           continue;
                   sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
                   if (IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr))
                           return sin6->sin6_scope_id & 0xffff;
           }
   
           return -1;
   }
   
   int
   in6_mask2len(mask, lim0)
           struct in6_addr *mask;
           u_char *lim0;
   {
           int x = 0, y;
           u_char *lim = lim0, *p;
   
           if (lim0 == NULL ||
               lim0 - (u_char *)mask > sizeof(*mask)) /* ignore the scope_id part */
                   lim = (u_char *)mask + sizeof(*mask);
           for (p = (u_char *)mask; p < lim; x++, p++) {
                   if (*p != 0xff)
                           break;
           }
           y = 0;
           if (p < lim) {
                   for (y = 0; y < 8; y++) {
                           if ((*p & (0x80 >> y)) == 0)
                                   break;
                   }
           }
   
           /*
            * when the limit pointer is given, do a stricter check on the
            * remaining bits.
            */
           if (p < lim) {
                   if (y != 0 && (*p & (0x00ff >> y)) != 0)
                           return(-1);
                   for (p = p + 1; p < lim; p++)
                           if (*p != 0)
                                   return(-1);
           }
           
           return x * 8 + y;
   }
   
   void
   in6_len2mask(mask, len)
           struct in6_addr *mask;
           int len;
   {
           int i;
   
           bzero(mask, sizeof(*mask));
           for (i = 0; i < len / 8; i++)
                   mask->s6_addr8[i] = 0xff;
           if (len % 8)
                   mask->s6_addr8[i] = (0xff00 >> (len % 8)) & 0xff;
   }
   
   #define ifa2ia6(ifa)    ((struct in6_ifaddr *)(ifa))
   #define ia62ifa(ia6)    (&((ia6)->ia_ifa))
   
   int
   in6_control(so, cmd, data, ifp, p)
           struct  socket *so;
           u_long cmd;
           caddr_t data;
           struct ifnet *ifp;
           struct proc *p;
   {
           struct  in6_ifreq *ifr = (struct in6_ifreq *)data;
           struct  in6_ifaddr *ia = NULL;
           struct  in6_aliasreq *ifra = (struct in6_aliasreq *)data;
           int privileged;
   
           privileged = 0;
           if (p == NULL || !suser(p))
                   privileged++;
   
           switch (cmd) {
           case SIOCGETSGCNT_IN6:
           case SIOCGETMIFCNT_IN6:
                   return (mrt6_ioctl(cmd, data));
           }
   
           if (ifp == NULL)
                   return(EOPNOTSUPP);
   
           switch (cmd) {
           case SIOCSNDFLUSH_IN6:
           case SIOCSPFXFLUSH_IN6:
           case SIOCSRTRFLUSH_IN6:
           case SIOCSDEFIFACE_IN6:
           case SIOCSIFINFO_FLAGS:
                   if (!privileged)
                           return(EPERM);
                   /* fall through */
           case OSIOCGIFINFO_IN6:
           case SIOCGIFINFO_IN6:
           case SIOCGDRLST_IN6:
           case SIOCGPRLST_IN6:
           case SIOCGNBRINFO_IN6:
           case SIOCGDEFIFACE_IN6:
                   return(nd6_ioctl(cmd, data, ifp));
           }
   
           switch (cmd) {
           case SIOCSIFPREFIX_IN6:
           case SIOCDIFPREFIX_IN6:
           case SIOCAIFPREFIX_IN6:
           case SIOCCIFPREFIX_IN6:
           case SIOCSGIFPREFIX_IN6:
           case SIOCGIFPREFIX_IN6:
                   log(LOG_NOTICE,
                       "prefix ioctls are now invalidated. "
                       "please use ifconfig.\n");
                   return(EOPNOTSUPP);
           }
   
           switch (cmd) {
           case SIOCSSCOPE6:
                   if (!privileged)
                           return(EPERM);
                   return(scope6_set(ifp, ifr->ifr_ifru.ifru_scope_id));
                   break;
           case SIOCGSCOPE6:
                   return(scope6_get(ifp, ifr->ifr_ifru.ifru_scope_id));
                   break;
           case SIOCGSCOPE6DEF:
                   return(scope6_get_default(ifr->ifr_ifru.ifru_scope_id));
                   break;
           }
   
           switch (cmd) {
           case SIOCALIFADDR:
           case SIOCDLIFADDR:
                   if (!privileged)
                           return(EPERM);
                   /* fall through */
           case SIOCGLIFADDR:
                   return in6_lifaddr_ioctl(so, cmd, data, ifp, p);
           }
   
           /*
            * Find address for this interface, if it exists.
            */
           if (ifra->ifra_addr.sin6_family == AF_INET6) { /* XXX */
                   struct sockaddr_in6 *sa6 =
                           (struct sockaddr_in6 *)&ifra->ifra_addr;
   
                   if (IN6_IS_ADDR_LINKLOCAL(&sa6->sin6_addr)) {
                           if (sa6->sin6_addr.s6_addr16[1] == 0) {
                                   /* link ID is not embedded by the user */
                                   sa6->sin6_addr.s6_addr16[1] =
                                           htons(ifp->if_index);
                           } else if (sa6->sin6_addr.s6_addr16[1] !=
                                       htons(ifp->if_index)) {
                                   return(EINVAL); /* link ID contradicts */
                           }
                           if (sa6->sin6_scope_id) {
                                   if (sa6->sin6_scope_id !=
                                       (u_int32_t)ifp->if_index)
                                           return(EINVAL);
                                   sa6->sin6_scope_id = 0; /* XXX: good way? */
                           }
                   }
                   ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr);
           }
   
           switch (cmd) {
           case SIOCSIFADDR_IN6:
           case SIOCSIFDSTADDR_IN6:
           case SIOCSIFNETMASK_IN6:
                   /*
                    * Since IPv6 allows a node to assign multiple addresses
                    * on a single interface, SIOCSIFxxx ioctls are not suitable
                    * and should be unused.
                    */
                   /* we decided to obsolete this command (20000704) */
                   return(EINVAL);
   
           case SIOCDIFADDR_IN6:
                   /*
                    * for IPv4, we look for existing in_ifaddr here to allow
                    * "ifconfig if0 delete" to remove first IPv4 address on the
                    * interface.  For IPv6, as the spec allow multiple interface
                    * address from the day one, we consider "remove the first one"
                    * semantics to be not preferable.
                    */
                   if (ia == NULL)
                           return(EADDRNOTAVAIL);
                   /* FALLTHROUGH */
           case SIOCAIFADDR_IN6:
                   /*
                    * We always require users to specify a valid IPv6 address for
                    * the corresponding operation.
                    */
                   if (ifra->ifra_addr.sin6_family != AF_INET6 ||
                       ifra->ifra_addr.sin6_len != sizeof(struct sockaddr_in6))
                           return(EAFNOSUPPORT);
                   if (!privileged)
                           return(EPERM);
   
                   break;
   
           case SIOCGIFADDR_IN6:
                   /* This interface is basically deprecated. use SIOCGIFCONF. */
                   /* fall through */
           case SIOCGIFAFLAG_IN6:
           case SIOCGIFNETMASK_IN6:
           case SIOCGIFDSTADDR_IN6:
           case SIOCGIFALIFETIME_IN6:
                   /* must think again about its semantics */
                   if (ia == NULL)
                           return(EADDRNOTAVAIL);
                   break;
           case SIOCSIFALIFETIME_IN6:
               {
                   struct in6_addrlifetime *lt;
   
                   if (!privileged)
                           return(EPERM);
                   if (ia == NULL)
                           return(EADDRNOTAVAIL);
                   /* sanity for overflow - beware unsigned */
                   lt = &ifr->ifr_ifru.ifru_lifetime;
                   if (lt->ia6t_vltime != ND6_INFINITE_LIFETIME
                    && lt->ia6t_vltime + time_second < time_second) {
                           return EINVAL;
                   }
                   if (lt->ia6t_pltime != ND6_INFINITE_LIFETIME
                    && lt->ia6t_pltime + time_second < time_second) {
                           return EINVAL;
                   }
                   break;
               }
           }
   
           switch (cmd) {
   
           case SIOCGIFADDR_IN6:
                   ifr->ifr_addr = ia->ia_addr;
                   break;
   
           case SIOCGIFDSTADDR_IN6:
                   if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                           return(EINVAL);
                   /*
                    * XXX: should we check if ifa_dstaddr is NULL and return
                    * an error?
                    */
                   ifr->ifr_dstaddr = ia->ia_dstaddr;
                   break;
   
           case SIOCGIFNETMASK_IN6:
                   ifr->ifr_addr = ia->ia_prefixmask;
                   break;
   
           case SIOCGIFAFLAG_IN6:
                   ifr->ifr_ifru.ifru_flags6 = ia->ia6_flags;
                   break;
   
           case SIOCGIFSTAT_IN6:
                   if (ifp == NULL)
                           return EINVAL;
                   if (in6_ifstat == NULL || ifp->if_index >= in6_ifstatmax
                    || in6_ifstat[ifp->if_index] == NULL) {
                           /* return EAFNOSUPPORT? */
                           bzero(&ifr->ifr_ifru.ifru_stat,
                                   sizeof(ifr->ifr_ifru.ifru_stat));
                   } else
                           ifr->ifr_ifru.ifru_stat = *in6_ifstat[ifp->if_index];
                   break;
   
           case SIOCGIFSTAT_ICMP6:
                   if (ifp == NULL)
                           return EINVAL;
                   if (icmp6_ifstat == NULL || ifp->if_index >= icmp6_ifstatmax ||
                       icmp6_ifstat[ifp->if_index] == NULL) {
                           /* return EAFNOSUPPORT? */
                           bzero(&ifr->ifr_ifru.ifru_stat,
                                   sizeof(ifr->ifr_ifru.ifru_icmp6stat));
                   } else
                           ifr->ifr_ifru.ifru_icmp6stat =
                                   *icmp6_ifstat[ifp->if_index];
                   break;
   
           case SIOCGIFALIFETIME_IN6:
                   ifr->ifr_ifru.ifru_lifetime = ia->ia6_lifetime;
                   break;
   
           case SIOCSIFALIFETIME_IN6:
                   ia->ia6_lifetime = ifr->ifr_ifru.ifru_lifetime;
                   /* for sanity */
                   if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                           ia->ia6_lifetime.ia6t_expire =
                                   time_second + ia->ia6_lifetime.ia6t_vltime;
                   } else
                           ia->ia6_lifetime.ia6t_expire = 0;
                   if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                           ia->ia6_lifetime.ia6t_preferred =
                                   time_second + ia->ia6_lifetime.ia6t_pltime;
                   } else
                           ia->ia6_lifetime.ia6t_preferred = 0;
                   break;
   
           case SIOCAIFADDR_IN6:
           {
                   int i, error = 0;
                   struct nd_prefix pr0, *pr;
   
                   /*
                    * first, make or update the interface address structure,
                    * and link it to the list.
                    */
                   if ((error = in6_update_ifa(ifp, ifra, ia)) != 0)
                           return(error);
   
                   /*
                    * then, make the prefix on-link on the interface.
                    * XXX: we'd rather create the prefix before the address, but
                    * we need at least one address to install the corresponding
                    * interface route, so we configure the address first.
                    */
   
                   /*
                    * convert mask to prefix length (prefixmask has already
                    * been validated in in6_update_ifa().
                    */
                   bzero(&pr0, sizeof(pr0));
                   pr0.ndpr_ifp = ifp;
                   pr0.ndpr_plen = in6_mask2len(&ifra->ifra_prefixmask.sin6_addr,
                                                NULL);
                   if (pr0.ndpr_plen == 128)
                           break;  /* we don't need to install a host route. */
                   pr0.ndpr_prefix = ifra->ifra_addr;
                   pr0.ndpr_mask = ifra->ifra_prefixmask.sin6_addr;
                   /* apply the mask for safety. */
                   for (i = 0; i < 4; i++) {
                           pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
                                   ifra->ifra_prefixmask.sin6_addr.s6_addr32[i];
                   }
                   /*
                    * XXX: since we don't have an API to set prefix (not address)
                    * lifetimes, we just use the same lifetimes as addresses.
                    * The (temporarily) installed lifetimes can be overridden by
                    * later advertised RAs (when accept_rtadv is non 0), which is
                    * an intended behavior.
                    */
                   pr0.ndpr_raf_onlink = 1; /* should be configurable? */
                   pr0.ndpr_raf_auto =
                           ((ifra->ifra_flags & IN6_IFF_AUTOCONF) != 0);
                   pr0.ndpr_vltime = ifra->ifra_lifetime.ia6t_vltime;
                   pr0.ndpr_pltime = ifra->ifra_lifetime.ia6t_pltime;
   
                   /* add the prefix if there's one. */
                   if ((pr = nd6_prefix_lookup(&pr0)) == NULL) {
                           /*
                            * nd6_prelist_add will install the corresponding
                            * interface route.
                            */
                           if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0)
                                   return(error);
                           if (pr == NULL) {
                                   log(LOG_ERR, "nd6_prelist_add succedded but "
                                       "no prefix\n");
                                   return(EINVAL); /* XXX panic here? */
                           }
                   }
                   if ((ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr))
                       == NULL) {
                           /* XXX: this should not happen! */
                           log(LOG_ERR, "in6_control: addition succeeded, but"
                               " no ifaddr\n");
                   } else {
                           if ((ia->ia6_flags & IN6_IFF_AUTOCONF) != 0 &&
                               ia->ia6_ndpr == NULL) { /* new autoconfed addr */
                                   ia->ia6_ndpr = pr;
                                   pr->ndpr_refcnt++;
   
                                   /*
                                    * If this is the first autoconf address from
                                    * the prefix, create a temporary address
                                    * as well (when specified).
                                    */
                                   if (ip6_use_tempaddr &&
                                       pr->ndpr_refcnt == 1) {
                                           int e;
                                           if ((e = in6_tmpifadd(ia, 1)) != 0) {
                                                   log(LOG_NOTICE, "in6_control: "
                                                       "failed to create a "
                                                       "temporary address, "
                                                       "errno=%d\n",
                                                       e);
                                           }
                                   }
                           }
   
                           /*
                            * this might affect the status of autoconfigured
                            * addresses, that is, this address might make
                            * other addresses detached.
                            */
                           pfxlist_onlink_check();
                   }
                   break;
           }
   
           case SIOCDIFADDR_IN6:
           {
                   int i = 0;
                   struct nd_prefix pr0, *pr;
   
                   /*
                    * If the address being deleted is the only one that owns
                    * the corresponding prefix, expire the prefix as well.
                    * XXX: theoretically, we don't have to warry about such
                    * relationship, since we separate the address management
                    * and the prefix management.  We do this, however, to provide
                    * as much backward compatibility as possible in terms of
                    * the ioctl operation.
                    */
                   bzero(&pr0, sizeof(pr0));
                   pr0.ndpr_ifp = ifp;
                   pr0.ndpr_plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr,
                                                NULL);
                   if (pr0.ndpr_plen == 128)
                           goto purgeaddr;
                   pr0.ndpr_prefix = ia->ia_addr;
                   pr0.ndpr_mask = ia->ia_prefixmask.sin6_addr;
                   for (i = 0; i < 4; i++) {
                           pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
                                   ia->ia_prefixmask.sin6_addr.s6_addr32[i];
                   }
                   /*
                    * The logic of the following condition is a bit complicated.
                    * We expire the prefix when
                    * 1. the address obeys autoconfiguration and it is the
                    *    only owner of the associated prefix, or
                    * 2. the address does not obey autoconf and there is no
                    *    other owner of the prefix.
                    */
                   if ((pr = nd6_prefix_lookup(&pr0)) != NULL &&
                       (((ia->ia6_flags & IN6_IFF_AUTOCONF) != 0 &&
                         pr->ndpr_refcnt == 1) ||
                        ((ia->ia6_flags & IN6_IFF_AUTOCONF) == 0 &&
                         pr->ndpr_refcnt == 0))) {
                           pr->ndpr_expire = 1; /* XXX: just for expiration */
                   }
   
             purgeaddr:
                   in6_purgeaddr(&ia->ia_ifa);
                   break;
           }
   
           default:
                   if (ifp == NULL || ifp->if_ioctl == 0)
                           return(EOPNOTSUPP);
                   return((*ifp->if_ioctl)(ifp, cmd, data));
           }
   
           return(0);
   }
   
   /*
    * Update parameters of an IPv6 interface address.
    * If necessary, a new entry is created and linked into address chains.
    * This function is separated from in6_control().
    * XXX: should this be performed under splnet()?
    */
   int
   in6_update_ifa(ifp, ifra, ia)
           struct ifnet *ifp;
           struct in6_aliasreq *ifra;
           struct in6_ifaddr *ia;
   {
           int error = 0, hostIsNew = 0, plen = -1;
           struct in6_ifaddr *oia;
           struct sockaddr_in6 dst6;
           struct in6_addrlifetime *lt;
   
           /* Validate parameters */
           if (ifp == NULL || ifra == NULL) /* this maybe redundant */
                   return(EINVAL);
   
           /*
            * The destination address for a p2p link must have a family
            * of AF_UNSPEC or AF_INET6.
            */
           if ((ifp->if_flags & IFF_POINTOPOINT) != 0 &&
               ifra->ifra_dstaddr.sin6_family != AF_INET6 &&
               ifra->ifra_dstaddr.sin6_family != AF_UNSPEC)
                   return(EAFNOSUPPORT);
           /*
            * validate ifra_prefixmask.  don't check sin6_family, netmask
            * does not carry fields other than sin6_len.
            */
           if (ifra->ifra_prefixmask.sin6_len > sizeof(struct sockaddr_in6))
                   return(EINVAL);
           /*
            * Because the IPv6 address architecture is classless, we require
            * users to specify a (non 0) prefix length (mask) for a new address.
            * We also require the prefix (when specified) mask is valid, and thus
            * reject a non-consecutive mask.
            */
           if (ia == NULL && ifra->ifra_prefixmask.sin6_len == 0)
                   return(EINVAL);
           if (ifra->ifra_prefixmask.sin6_len != 0) {
                   plen = in6_mask2len(&ifra->ifra_prefixmask.sin6_addr,
                                       (u_char *)&ifra->ifra_prefixmask +
                                       ifra->ifra_prefixmask.sin6_len);
                   if (plen <= 0)
                           return(EINVAL);
           }
           else {
                   /*
                    * In this case, ia must not be NULL.  We just use its prefix
                    * length.
                    */
                   plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL);
           }
           /*
            * If the destination address on a p2p interface is specified,
            * and the address is a scoped one, validate/set the scope
            * zone identifier.
            */
           dst6 = ifra->ifra_dstaddr;
           if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) &&
               (dst6.sin6_family == AF_INET6)) {
                   int scopeid;
   
   #ifndef SCOPEDROUTING
                   if ((error = in6_recoverscope(&dst6,
                                                 &ifra->ifra_dstaddr.sin6_addr,
                                                 ifp)) != 0)
                           return(error);
   #endif
                   scopeid = in6_addr2scopeid(ifp, &dst6.sin6_addr);
                   if (dst6.sin6_scope_id == 0) /* user omit to specify the ID. */
                           dst6.sin6_scope_id = scopeid;
                   else if (dst6.sin6_scope_id != scopeid)
                           return(EINVAL); /* scope ID mismatch. */
   #ifndef SCOPEDROUTING
                   if ((error = in6_embedscope(&dst6.sin6_addr, &dst6, NULL, NULL))
                       != 0)
                           return(error);
                   dst6.sin6_scope_id = 0; /* XXX */
   #endif
           }
           /*
            * The destination address can be specified only for a p2p or a
            * loopback interface.  If specified, the corresponding prefix length
            * must be 128.
            */
           if (ifra->ifra_dstaddr.sin6_family == AF_INET6) {
                   if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) == 0) {
                           /* XXX: noisy message */
                           log(LOG_INFO, "in6_update_ifa: a destination can be "
                               "specified for a p2p or a loopback IF only\n");
                           return(EINVAL);
                   }
                   if (plen != 128) {
                           /*
                            * The following message seems noisy, but we dare to
                            * add it for diagnosis.
                            */
                           log(LOG_INFO, "in6_update_ifa: prefixlen must be 128 "
                               "when dstaddr is specified\n");
                           return(EINVAL);
                   }
           }
           /* lifetime consistency check */
           lt = &ifra->ifra_lifetime;
           if (lt->ia6t_vltime != ND6_INFINITE_LIFETIME
               && lt->ia6t_vltime + time_second < time_second) {
                   return EINVAL;
           }
           if (lt->ia6t_vltime == 0) {
                   /*
                    * the following log might be noisy, but this is a typical
                    * configuration mistake or a tool's bug.
                    */
                   log(LOG_INFO,
                       "in6_update_ifa: valid lifetime is 0 for %s\n",
                       ip6_sprintf(&ifra->ifra_addr.sin6_addr));
           }
           if (lt->ia6t_pltime != ND6_INFINITE_LIFETIME
               && lt->ia6t_pltime + time_second < time_second) {
                   return EINVAL;
           }
   
           /*
            * If this is a new address, allocate a new ifaddr and link it
            * into chains.
            */
           if (ia == NULL) {
                   hostIsNew = 1;
                   /*
                    * When in6_update_ifa() is called in a process of a received
                    * RA, it is called under splnet().  So, we should call malloc
                    * with M_NOWAIT.
                    */
                   ia = (struct in6_ifaddr *)
                           malloc(sizeof(*ia), M_IFADDR, M_NOWAIT);
                   if (ia == NULL)
                           return (ENOBUFS);
                   bzero((caddr_t)ia, sizeof(*ia));
                   /* Initialize the address and masks */
                   ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
                   ia->ia_addr.sin6_family = AF_INET6;
                   ia->ia_addr.sin6_len = sizeof(ia->ia_addr);
                   if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) != 0) {
                           /*
                            * XXX: some functions expect that ifa_dstaddr is not
                            * NULL for p2p interfaces.
                            */
                           ia->ia_ifa.ifa_dstaddr
                                   = (struct sockaddr *)&ia->ia_dstaddr;
                   } else {
                           ia->ia_ifa.ifa_dstaddr = NULL;
                   }
                   ia->ia_ifa.ifa_netmask
                           = (struct sockaddr *)&ia->ia_prefixmask;
   
                   ia->ia_ifp = ifp;
                   if ((oia = in6_ifaddr) != NULL) {
                           for ( ; oia->ia_next; oia = oia->ia_next)
                                   continue;
                           oia->ia_next = ia;
                   } else
                           in6_ifaddr = ia;
   
                   TAILQ_INSERT_TAIL(&ifp->if_addrlist, &ia->ia_ifa,
                                     ifa_list);
           }
   
           /* set prefix mask */
           if (ifra->ifra_prefixmask.sin6_len) {
                   /*
                    * We prohibit changing the prefix length of an existing
                    * address, because
                    * + such an operation should be rare in IPv6, and
                    * + the operation would confuse prefix management.
                    */
                   if (ia->ia_prefixmask.sin6_len &&
                       in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL) != plen) {
                           log(LOG_INFO, "in6_update_ifa: the prefix length of an"
                               " existing (%s) address should not be changed\n",
                               ip6_sprintf(&ia->ia_addr.sin6_addr));
                           error = EINVAL;
                           goto unlink;
                   }
                   ia->ia_prefixmask = ifra->ifra_prefixmask;
           }
   
           /*
            * If a new destination address is specified, scrub the old one and
            * install the new destination.  Note that the interface must be
            * p2p or loopback (see the check above.) 
            */
           if (dst6.sin6_family == AF_INET6 &&
               !IN6_ARE_ADDR_EQUAL(&dst6.sin6_addr,
                                   &ia->ia_dstaddr.sin6_addr)) {
                   int e;
   
                   if ((ia->ia_flags & IFA_ROUTE) != 0 &&
                       (e = rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST))
                       != 0) {
                           log(LOG_ERR, "in6_update_ifa: failed to remove "
                               "a route to the old destination: %s\n",
                               ip6_sprintf(&ia->ia_addr.sin6_addr));
                           /* proceed anyway... */
                   }
                   else
                           ia->ia_flags &= ~IFA_ROUTE;
                   ia->ia_dstaddr = dst6;
           }
   
           /* reset the interface and routing table appropriately. */
           if ((error = in6_ifinit(ifp, ia, &ifra->ifra_addr, hostIsNew)) != 0)
                   goto unlink;
   
           /*
            * Beyond this point, we should call in6_purgeaddr upon an error,
            * not just go to unlink. 
            */
   
   #if 0                           /* disable this mechanism for now */
           /* update prefix list */
           if (hostIsNew &&
               (ifra->ifra_flags & IN6_IFF_NOPFX) == 0) { /* XXX */
                   int iilen;
   
                   iilen = (sizeof(ia->ia_prefixmask.sin6_addr) << 3) - plen;
                   if ((error = in6_prefix_add_ifid(iilen, ia)) != 0) {
                           in6_purgeaddr((struct ifaddr *)ia);
                           return(error);
                  }
          }
  #endif
  
          if ((ifp->if_flags & IFF_MULTICAST) != 0) {
                  struct sockaddr_in6 mltaddr, mltmask;
                  struct in6_multi *in6m;
  
                  if (hostIsNew) {
                          /*
                           * join solicited multicast addr for new host id
                           */
                          struct in6_addr llsol;
                          bzero(&llsol, sizeof(struct in6_addr));
                          llsol.s6_addr16[0] = htons(0xff02);
                          llsol.s6_addr16[1] = htons(ifp->if_index);
                          llsol.s6_addr32[1] = 0;
                          llsol.s6_addr32[2] = htonl(1);
                          llsol.s6_addr32[3] =
                                  ifra->ifra_addr.sin6_addr.s6_addr32[3];
                          llsol.s6_addr8[12] = 0xff;
                          (void)in6_addmulti(&llsol, ifp, &error);
                          if (error != 0) {
                                  log(LOG_WARNING,
                                      "in6_update_ifa: addmulti failed for "
                                      "%s on %s (errno=%d)\n",
                                      ip6_sprintf(&llsol), if_name(ifp),
                                      error);
                                  in6_purgeaddr((struct ifaddr *)ia);
                                  return(error);
                          }
                  }
  
                  bzero(&mltmask, sizeof(mltmask));
                  mltmask.sin6_len = sizeof(struct sockaddr_in6);
                  mltmask.sin6_family = AF_INET6;
                  mltmask.sin6_addr = in6mask32;
  
                  /*
                   * join link-local all-nodes address
                   */
                  bzero(&mltaddr, sizeof(mltaddr));
                  mltaddr.sin6_len = sizeof(struct sockaddr_in6);
                  mltaddr.sin6_family = AF_INET6;
                  mltaddr.sin6_addr = in6addr_linklocal_allnodes;
                  mltaddr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
  
                  IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                  if (in6m == NULL) {
                          rtrequest(RTM_ADD,
                                    (struct sockaddr *)&mltaddr,
                                    (struct sockaddr *)&ia->ia_addr,
                                    (struct sockaddr *)&mltmask,
                                    RTF_UP|RTF_CLONING,  /* xxx */
                                    (struct rtentry **)0);
                          (void)in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
                          if (error != 0) {
                                  log(LOG_WARNING,
                                      "in6_update_ifa: addmulti failed for "
                                      "%s on %s (errno=%d)\n",
                                      ip6_sprintf(&mltaddr.sin6_addr), 
                                      if_name(ifp), error);
                          }
                  }
  
                  /*
                   * join node information group address
                   */
  #define hostnamelen     strlen(hostname)
                  if (in6_nigroup(ifp, hostname, hostnamelen, &mltaddr.sin6_addr)
                      == 0) {
                          IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                          if (in6m == NULL && ia != NULL) {
                                  (void)in6_addmulti(&mltaddr.sin6_addr,
                                      ifp, &error);
                                  if (error != 0) {
                                          log(LOG_WARNING, "in6_update_ifa: "
                                              "addmulti failed for "
                                              "%s on %s (errno=%d)\n",
                                              ip6_sprintf(&mltaddr.sin6_addr), 
                                              if_name(ifp), error);
                                  }
                          }
                  }
  #undef hostnamelen
  
                  /*
                   * join node-local all-nodes address, on loopback.
                   * XXX: since "node-local" is obsoleted by interface-local,
                   *      we have to join the group on every interface with
                   *      some interface-boundary restriction.
                   */
                  if (ifp->if_flags & IFF_LOOPBACK) {
                          struct in6_ifaddr *ia_loop;
  
                          struct in6_addr loop6 = in6addr_loopback;
                          ia_loop = in6ifa_ifpwithaddr(ifp, &loop6);
  
                          mltaddr.sin6_addr = in6addr_nodelocal_allnodes;
  
                          IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                          if (in6m == NULL && ia_loop != NULL) {
                                  rtrequest(RTM_ADD,
                                            (struct sockaddr *)&mltaddr,
                                            (struct sockaddr *)&ia_loop->ia_addr,
                                            (struct sockaddr *)&mltmask,
                                            RTF_UP,
                                            (struct rtentry **)0);
                                  (void)in6_addmulti(&mltaddr.sin6_addr, ifp,
                                                     &error);
                                  if (error != 0) {
                                          log(LOG_WARNING, "in6_update_ifa: "
                                              "addmulti failed for %s on %s "
                                              "(errno=%d)\n",
                                              ip6_sprintf(&mltaddr.sin6_addr), 
                                              if_name(ifp), error);
                                  }
                          }
                  }
          }
  
          ia->ia6_flags = ifra->ifra_flags;
          ia->ia6_flags &= ~IN6_IFF_DUPLICATED;   /*safety*/
          ia->ia6_flags &= ~IN6_IFF_NODAD;        /* Mobile IPv6 */
  
          ia->ia6_lifetime = ifra->ifra_lifetime;
          /* for sanity */
          if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                  ia->ia6_lifetime.ia6t_expire =
                          time_second + ia->ia6_lifetime.ia6t_vltime;
          } else
                  ia->ia6_lifetime.ia6t_expire = 0;
          if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                  ia->ia6_lifetime.ia6t_preferred =
                          time_second + ia->ia6_lifetime.ia6t_pltime;
          } else
                  ia->ia6_lifetime.ia6t_preferred = 0;
  
          /*
           * make sure to initialize ND6 information.  this is to workaround
           * issues with interfaces with IPv6 addresses, which have never brought
           * up.  We are assuming that it is safe to nd6_ifattach multiple times.
           */
          nd6_ifattach(ifp);
  
          /*
           * Perform DAD, if needed.
           * XXX It may be of use, if we can administratively
           * disable DAD.
           */
          if (in6if_do_dad(ifp) && (ifra->ifra_flags & IN6_IFF_NODAD) == 0) {
                  ia->ia6_flags |= IN6_IFF_TENTATIVE;
                  nd6_dad_start((struct ifaddr *)ia, NULL);
          }
  
          return(error);
  
    unlink:
          /*
           * XXX: if a change of an existing address failed, keep the entry
           * anyway.
           */
          if (hostIsNew)
                  in6_unlink_ifa(ia, ifp);
          return(error);
  }
  
  void
  in6_purgeaddr(ifa)
          struct ifaddr *ifa;
  {
          struct ifnet *ifp = ifa->ifa_ifp;
          struct in6_ifaddr *ia = (struct in6_ifaddr *) ifa;
  
          /* stop DAD processing */
          nd6_dad_stop(ifa);
  
          /*
           * delete route to the destination of the address being purged.
           * The interface must be p2p or loopback in this case.
           */
          if ((ia->ia_flags & IFA_ROUTE) != 0 && ia->ia_dstaddr.sin6_len != 0) {
                  int e;
  
                  if ((e = rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST))
                      != 0) {
                          log(LOG_ERR, "in6_purgeaddr: failed to remove "
                              "a route to the p2p destination: %s on %s, "
                              "errno=%d\n",
                              ip6_sprintf(&ia->ia_addr.sin6_addr), if_name(ifp),
                              e);
                          /* proceed anyway... */
                  }
                  else
                          ia->ia_flags &= ~IFA_ROUTE;
          }
  
          /* Remove ownaddr's loopback rtentry, if it exists. */
          in6_ifremloop(&(ia->ia_ifa));
  
          if (ifp->if_flags & IFF_MULTICAST) {
                  /*
                   * delete solicited multicast addr for deleting host id
                   */
                  struct in6_multi *in6m;
                  struct in6_addr llsol;
                  bzero(&llsol, sizeof(struct in6_addr));
                  llsol.s6_addr16[0] = htons(0xff02);
                  llsol.s6_addr16[1] = htons(ifp->if_index);
                  llsol.s6_addr32[1] = 0;
                  llsol.s6_addr32[2] = htonl(1);
                  llsol.s6_addr32[3] =
                          ia->ia_addr.sin6_addr.s6_addr32[3];
                  llsol.s6_addr8[12] = 0xff;
  
                  IN6_LOOKUP_MULTI(llsol, ifp, in6m);
                  if (in6m)
                          in6_delmulti(in6m);
          }
  
          in6_unlink_ifa(ia, ifp);
  }
  
  static void
  in6_unlink_ifa(ia, ifp)
          struct in6_ifaddr *ia;
          struct ifnet *ifp;
  {
          int plen, iilen;
          struct in6_ifaddr *oia;
          int     s = splnet();
  
          TAILQ_REMOVE(&ifp->if_addrlist, &ia->ia_ifa, ifa_list);
  
          oia = ia;
          if (oia == (ia = in6_ifaddr))
                  in6_ifaddr = ia->ia_next;
          else {
                  while (ia->ia_next && (ia->ia_next != oia))
                          ia = ia->ia_next;
                  if (ia->ia_next)
                          ia->ia_next = oia->ia_next;
                  else {
                          /* search failed */
                          printf("Couldn't unlink in6_ifaddr from in6_ifaddr\n");
                  }
          }
  
          if (oia->ia6_ifpr) {    /* check for safety */
                  plen = in6_mask2len(&oia->ia_prefixmask.sin6_addr, NULL);
                  iilen = (sizeof(oia->ia_prefixmask.sin6_addr) << 3) - plen;
                  in6_prefix_remove_ifid(iilen, oia);
          }
  
          /*
           * When an autoconfigured address is being removed, release the
           * reference to the base prefix.  Also, since the release might
           * affect the status of other (detached) addresses, call
           * pfxlist_onlink_check().
           */
          if ((oia->ia6_flags & IN6_IFF_AUTOCONF) != 0) {
                  if (oia->ia6_ndpr == NULL) {
                          log(LOG_NOTICE, "in6_unlink_ifa: autoconf'ed address "
                              "%p has no prefix\n", oia);
                  } else {
                          oia->ia6_ndpr->ndpr_refcnt--;
                          oia->ia6_flags &= ~IN6_IFF_AUTOCONF;
                          oia->ia6_ndpr = NULL;
                  }
  
                  pfxlist_onlink_check();
          }
  
          /*
           * release another refcnt for the link from in6_ifaddr.
           * Note that we should decrement the refcnt at least once for all *BSD.
           */
          IFAFREE(&oia->ia_ifa);
  
          splx(s);
  }
  
  void
  in6_purgeif(ifp)
          struct ifnet *ifp;
  {
          struct ifaddr *ifa, *nifa;
  
          for (ifa = TAILQ_FIRST(&ifp->if_addrlist); ifa != NULL; ifa = nifa)
          {
                  nifa = TAILQ_NEXT(ifa, ifa_list);
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  in6_purgeaddr(ifa);
          }
  
          in6_ifdetach(ifp);
  }
  
  /*
   * SIOC[GAD]LIFADDR.
   *      SIOCGLIFADDR: get first address. (?)
   *      SIOCGLIFADDR with IFLR_PREFIX:
   *              get first address that matches the specified prefix.
   *      SIOCALIFADDR: add the specified address.
   *      SIOCALIFADDR with IFLR_PREFIX:
   *              add the specified prefix, filling hostid part from
   *              the first link-local address.  prefixlen must be <= 64.
   *      SIOCDLIFADDR: delete the specified address.
   *      SIOCDLIFADDR with IFLR_PREFIX:
   *              delete the first address that matches the specified prefix.
   * return values:
   *      EINVAL on invalid parameters
   *      EADDRNOTAVAIL on prefix match failed/specified address not found
   *      other values may be returned from in6_ioctl()
   *
   * NOTE: SIOCALIFADDR(with IFLR_PREFIX set) allows prefixlen less than 64.
   * this is to accomodate address naming scheme other than RFC2374,
   * in the future.
   * RFC2373 defines interface id to be 64bit, but it allows non-RFC2374
   * address encoding scheme. (see figure on page 8)
   */
  static int
  in6_lifaddr_ioctl(so, cmd, data, ifp, p)
          struct socket *so;
          u_long cmd;
          caddr_t data;
          struct ifnet *ifp;
          struct proc *p;
  {
          struct if_laddrreq *iflr = (struct if_laddrreq *)data;
          struct ifaddr *ifa;
          struct sockaddr *sa;
  
          /* sanity checks */
          if (!data || !ifp) {
                  panic("invalid argument to in6_lifaddr_ioctl");
                  /*NOTRECHED*/
          }
  
          switch (cmd) {
          case SIOCGLIFADDR:
                  /* address must be specified on GET with IFLR_PREFIX */
                  if ((iflr->flags & IFLR_PREFIX) == 0)
                          break;
                  /* FALLTHROUGH */
          case SIOCALIFADDR:
          case SIOCDLIFADDR:
                  /* address must be specified on ADD and DELETE */
                  sa = (struct sockaddr *)&iflr->addr;
                  if (sa->sa_family != AF_INET6)
                          return EINVAL;
                  if (sa->sa_len != sizeof(struct sockaddr_in6))
                          return EINVAL;
                  /* XXX need improvement */
                  sa = (struct sockaddr *)&iflr->dstaddr;
                  if (sa->sa_family && sa->sa_family != AF_INET6)
                          return EINVAL;
                  if (sa->sa_len && sa->sa_len != sizeof(struct sockaddr_in6))
                          return EINVAL;
                  break;
          default: /* shouldn't happen */
  #if 0
                  panic("invalid cmd to in6_lifaddr_ioctl");
                  /* NOTREACHED */
  #else
                  return EOPNOTSUPP;
  #endif
          }
          if (sizeof(struct in6_addr) * 8 < iflr->prefixlen)
                  return EINVAL;
  
          switch (cmd) {
          case SIOCALIFADDR:
              {
                  struct in6_aliasreq ifra;
                  struct in6_addr *hostid = NULL;
                  int prefixlen;
  
                  if ((iflr->flags & IFLR_PREFIX) != 0) {
                          struct sockaddr_in6 *sin6;
  
                          /*
                           * hostid is to fill in the hostid part of the
                           * address.  hostid points to the first link-local
                           * address attached to the interface.
                           */
                          ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0);
                          if (!ifa)
                                  return EADDRNOTAVAIL;
                          hostid = IFA_IN6(ifa);
  
                          /* prefixlen must be <= 64. */
                          if (64 < iflr->prefixlen)
                                  return EINVAL;
                          prefixlen = iflr->prefixlen;
  
                          /* hostid part must be zero. */
                          sin6 = (struct sockaddr_in6 *)&iflr->addr;
                          if (sin6->sin6_addr.s6_addr32[2] != 0
                           || sin6->sin6_addr.s6_addr32[3] != 0) {
                                  return EINVAL;
                          }
                  } else
                          prefixlen = iflr->prefixlen;
  
                  /* copy args to in6_aliasreq, perform ioctl(SIOCAIFADDR_IN6). */
                  bzero(&ifra, sizeof(ifra));
                  bcopy(iflr->iflr_name, ifra.ifra_name,
                          sizeof(ifra.ifra_name));
  
                  bcopy(&iflr->addr, &ifra.ifra_addr,
                          ((struct sockaddr *)&iflr->addr)->sa_len);
                  if (hostid) {
                          /* fill in hostid part */
                          ifra.ifra_addr.sin6_addr.s6_addr32[2] =
                                  hostid->s6_addr32[2];
                          ifra.ifra_addr.sin6_addr.s6_addr32[3] =
                                  hostid->s6_addr32[3];
                  }
  
                  if (((struct sockaddr *)&iflr->dstaddr)->sa_family) {   /*XXX*/
                          bcopy(&iflr->dstaddr, &ifra.ifra_dstaddr,
                                  ((struct sockaddr *)&iflr->dstaddr)->sa_len);
                          if (hostid) {
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[2] =
                                          hostid->s6_addr32[2];
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[3] =
                                          hostid->s6_addr32[3];
                          }
                  }
  
                  ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
                  in6_len2mask(&ifra.ifra_prefixmask.sin6_addr, prefixlen);
  
                  ifra.ifra_flags = iflr->flags & ~IFLR_PREFIX;
                  return in6_control(so, SIOCAIFADDR_IN6, (caddr_t)&ifra, ifp, p);
              }
          case SIOCGLIFADDR:
          case SIOCDLIFADDR:
              {
                  struct in6_ifaddr *ia;
                  struct in6_addr mask, candidate, match;
                  struct sockaddr_in6 *sin6;
                  int cmp;
  
                  bzero(&mask, sizeof(mask));
                  if (iflr->flags & IFLR_PREFIX) {
                          /* lookup a prefix rather than address. */
                          in6_len2mask(&mask, iflr->prefixlen);
  
                          sin6 = (struct sockaddr_in6 *)&iflr->addr;
                          bcopy(&sin6->sin6_addr, &match, sizeof(match));
                          match.s6_addr32[0] &= mask.s6_addr32[0];
                          match.s6_addr32[1] &= mask.s6_addr32[1];
                          match.s6_addr32[2] &= mask.s6_addr32[2];
                          match.s6_addr32[3] &= mask.s6_addr32[3];
  
                          /* if you set extra bits, that's wrong */
                          if (bcmp(&match, &sin6->sin6_addr, sizeof(match)))
                                  return EINVAL;
  
                          cmp = 1;
                  } else {
                          if (cmd == SIOCGLIFADDR) {
                                  /* on getting an address, take the 1st match */
                                  cmp = 0;        /* XXX */
                          } else {
                                  /* on deleting an address, do exact match */
                                  in6_len2mask(&mask, 128);
                                  sin6 = (struct sockaddr_in6 *)&iflr->addr;
                                  bcopy(&sin6->sin6_addr, &match, sizeof(match));
  
                                  cmp = 1;
                          }
                  }
  
                  TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
                  {
                          if (ifa->ifa_addr->sa_family != AF_INET6)
                                  continue;
                          if (!cmp)
                                  break;
  
                          bcopy(IFA_IN6(ifa), &candidate, sizeof(candidate));
  #ifndef SCOPEDROUTING
                          /*
                           * XXX: this is adhoc, but is necessary to allow
                           * a user to specify fe80::/64 (not /10) for a
                           * link-local address.
                           */
                          if (IN6_IS_ADDR_LINKLOCAL(&candidate))
                                  candidate.s6_addr16[1] = 0;
  #endif
                          candidate.s6_addr32[0] &= mask.s6_addr32[0];
                          candidate.s6_addr32[1] &= mask.s6_addr32[1];
                          candidate.s6_addr32[2] &= mask.s6_addr32[2];
                          candidate.s6_addr32[3] &= mask.s6_addr32[3];
                          if (IN6_ARE_ADDR_EQUAL(&candidate, &match))
                                  break;
                  }
                  if (!ifa)
                          return EADDRNOTAVAIL;
                  ia = ifa2ia6(ifa);
  
                  if (cmd == SIOCGLIFADDR) {
  #ifndef SCOPEDROUTING
                          struct sockaddr_in6 *s6;
  #endif
  
                          /* fill in the if_laddrreq structure */
                          bcopy(&ia->ia_addr, &iflr->addr, ia->ia_addr.sin6_len);
  #ifndef SCOPEDROUTING           /* XXX see above */
                          s6 = (struct sockaddr_in6 *)&iflr->addr;
                          if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr)) {
                                  s6->sin6_addr.s6_addr16[1] = 0;
                                  s6->sin6_scope_id =
                                          in6_addr2scopeid(ifp, &s6->sin6_addr);
                          }
  #endif
                          if ((ifp->if_flags & IFF_POINTOPOINT) != 0) {
                                  bcopy(&ia->ia_dstaddr, &iflr->dstaddr,
                                          ia->ia_dstaddr.sin6_len);
  #ifndef SCOPEDROUTING           /* XXX see above */
                                  s6 = (struct sockaddr_in6 *)&iflr->dstaddr;
                                  if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr)) {
                                          s6->sin6_addr.s6_addr16[1] = 0;
                                          s6->sin6_scope_id =
                                                  in6_addr2scopeid(ifp,
                                                                   &s6->sin6_addr);
                                  }
  #endif
                          } else
                                  bzero(&iflr->dstaddr, sizeof(iflr->dstaddr));
  
                          iflr->prefixlen =
                                  in6_mask2len(&ia->ia_prefixmask.sin6_addr,
                                               NULL);
  
                          iflr->flags = ia->ia6_flags;    /* XXX */
  
                          return 0;
                  } else {
                          struct in6_aliasreq ifra;
  
                          /* fill in6_aliasreq and do ioctl(SIOCDIFADDR_IN6) */
                          bzero(&ifra, sizeof(ifra));
                          bcopy(iflr->iflr_name, ifra.ifra_name,
                                  sizeof(ifra.ifra_name));
  
                          bcopy(&ia->ia_addr, &ifra.ifra_addr,
                                  ia->ia_addr.sin6_len);
                          if ((ifp->if_flags & IFF_POINTOPOINT) != 0) {
                                  bcopy(&ia->ia_dstaddr, &ifra.ifra_dstaddr,
                                          ia->ia_dstaddr.sin6_len);
                          } else {
                                  bzero(&ifra.ifra_dstaddr,
                                      sizeof(ifra.ifra_dstaddr));
                          }
                          bcopy(&ia->ia_prefixmask, &ifra.ifra_dstaddr,
                                  ia->ia_prefixmask.sin6_len);
  
                          ifra.ifra_flags = ia->ia6_flags;
                          return in6_control(so, SIOCDIFADDR_IN6, (caddr_t)&ifra,
                                  ifp, p);
                  }
              }
          }
  
          return EOPNOTSUPP;      /* just for safety */
  }
  
  /*
   * Initialize an interface's intetnet6 address
   * and routing table entry.
   */
  static int
  in6_ifinit(ifp, ia, sin6, newhost)
          struct ifnet *ifp;
          struct in6_ifaddr *ia;
          struct sockaddr_in6 *sin6;
          int newhost;
  {
          int     error = 0, plen, ifacount = 0;
          int     s = splimp();
          struct ifaddr *ifa;
  
          /*
           * Give the interface a chance to initialize
           * if this is its first address,
           * and to validate the address if necessary.
           */
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr == NULL)
                          continue;       /* just for safety */
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  ifacount++;
          }
  
          ia->ia_addr = *sin6;
  
          if (ifacount <= 1 && ifp->if_ioctl &&
              (error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia))) {
                  splx(s);
                  return(error);
          }
          splx(s);
  
          ia->ia_ifa.ifa_metric = ifp->if_metric;
  
          /* we could do in(6)_socktrim here, but just omit it at this moment. */
  
          /*
           * Special case:
           * If a new destination address is specified for a point-to-point
           * interface, install a route to the destination as an interface
           * direct route.
           * XXX: the logic below rejects assigning multiple addresses on a p2p
           * interface that share a same destination.
           */
          plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL); /* XXX */
          if (!(ia->ia_flags & IFA_ROUTE) && plen == 128 &&
              ia->ia_dstaddr.sin6_family == AF_INET6) {
                  if ((error = rtinit(&(ia->ia_ifa), (int)RTM_ADD,
                                      RTF_UP | RTF_HOST)) != 0)
                          return(error);
                  ia->ia_flags |= IFA_ROUTE;
          }
          if (plen < 128) {
                  /*
                   * The RTF_CLONING flag is necessary for in6_is_ifloop_auto().
                   */
                  ia->ia_ifa.ifa_flags |= RTF_CLONING;
          }
  
          /* Add ownaddr as loopback rtentry, if necessary (ex. on p2p link). */
          if (newhost) {
                  /* set the rtrequest function to create llinfo */
                  ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
                  in6_ifaddloop(&(ia->ia_ifa));
          }
  
          return(error);
  }
  
  /*
   * Add an address to the list of IP6 multicast addresses for a
   * given interface.
   */
  struct  in6_multi *
  in6_addmulti(maddr6, ifp, errorp)
          struct in6_addr *maddr6;
          struct ifnet *ifp;
          int *errorp;
  {
          struct  in6_multi *in6m;
          struct sockaddr_in6 sin6;
          struct ifmultiaddr *ifma;
          int     s = splnet();
  
          *errorp = 0;
  
          /*
           * Call generic routine to add membership or increment
           * refcount.  It wants addresses in the form of a sockaddr,
           * so we build one here (being careful to zero the unused bytes).
           */
          bzero(&sin6, sizeof sin6);
          sin6.sin6_family = AF_INET6;
          sin6.sin6_len = sizeof sin6;
          sin6.sin6_addr = *maddr6;
          *errorp = if_addmulti(ifp, (struct sockaddr *)&sin6, &ifma);
          if (*errorp) {
                  splx(s);
                  return 0;
          }
  
          /*
           * If ifma->ifma_protospec is null, then if_addmulti() created
           * a new record.  Otherwise, we are done.
           */
          if (ifma->ifma_protospec != 0) {
                  splx(s);
                  return ifma->ifma_protospec;
          }
  
          /* XXX - if_addmulti uses M_WAITOK.  Can this really be called
             at interrupt time?  If so, need to fix if_addmulti. XXX */
          in6m = (struct in6_multi *)malloc(sizeof(*in6m), M_IPMADDR, M_NOWAIT);
          if (in6m == NULL) {
                  splx(s);
                  return (NULL);
          }
  
          bzero(in6m, sizeof *in6m);
          in6m->in6m_addr = *maddr6;
          in6m->in6m_ifp = ifp;
          in6m->in6m_ifma = ifma;
          ifma->ifma_protospec = in6m;
          LIST_INSERT_HEAD(&in6_multihead, in6m, in6m_entry);
  
          /*
           * Let MLD6 know that we have joined a new IP6 multicast
           * group.
           */
          mld6_start_listening(in6m);
          splx(s);
          return(in6m);
  }
  
  /*
   * Delete a multicast address record.
   */
  void
  in6_delmulti(in6m)
          struct in6_multi *in6m;
  {
          struct ifmultiaddr *ifma = in6m->in6m_ifma;
          int     s = splnet();
  
          if (ifma->ifma_refcount == 1) {
                  /*
                   * No remaining claims to this record; let MLD6 know
                   * that we are leaving the multicast group.
                   */
                  mld6_stop_listening(in6m);
                  ifma->ifma_protospec = 0;
                  LIST_REMOVE(in6m, in6m_entry);
                  free(in6m, M_IPMADDR);
          }
          /* XXX - should be separate API for when we have an ifma? */
          if_delmulti(ifma->ifma_ifp, ifma->ifma_addr);
          splx(s);
  }
  
  /*
   * Find an IPv6 interface link-local address specific to an interface.
   */
  struct in6_ifaddr *
  in6ifa_ifpforlinklocal(ifp, ignoreflags)
          struct ifnet *ifp;
          int ignoreflags;
  {
          struct ifaddr *ifa;
  
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr == NULL)
                          continue;       /* just for safety */
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  if (IN6_IS_ADDR_LINKLOCAL(IFA_IN6(ifa))) {
                          if ((((struct in6_ifaddr *)ifa)->ia6_flags &
                               ignoreflags) != 0)
                                  continue;
                          break;
                  }
          }
  
          return((struct in6_ifaddr *)ifa);
  }
  
  
  /*
   * find the internet address corresponding to a given interface and address.
   */
  struct in6_ifaddr *
  in6ifa_ifpwithaddr(ifp, addr)
          struct ifnet *ifp;
          struct in6_addr *addr;
  {
          struct ifaddr *ifa;
  
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr == NULL)
                          continue;       /* just for safety */
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  if (IN6_ARE_ADDR_EQUAL(addr, IFA_IN6(ifa)))
                          break;
          }
  
          return((struct in6_ifaddr *)ifa);
  }
  
  /*
   * Convert IP6 address to printable (loggable) representation.
   */
  static char digits[] = "0123456789abcdef";
  static int ip6round = 0;
  char *
  ip6_sprintf(addr)
          const struct in6_addr *addr;
  {
          static char ip6buf[8][48];
          int i;
          char *cp;
          u_short *a = (u_short *)addr;
          u_char *d;
          int dcolon = 0;
  
          ip6round = (ip6round + 1) & 7;
          cp = ip6buf[ip6round];
  
          for (i = 0; i < 8; i++) {
                  if (dcolon == 1) {
                          if (*a == 0) {
                                  if (i == 7)
                                          *cp++ = ':';
                                  a++;
                                  continue;
                          } else
                                  dcolon = 2;
                  }
                  if (*a == 0) {
                          if (dcolon == 0 && *(a + 1) == 0) {
                                  if (i == 0)
                                          *cp++ = ':';
                                  *cp++ = ':';
                                  dcolon = 1;
                          } else {
                                  *cp++ = '';
                                  *cp++ = ':';
                          }
                          a++;
                          continue;
                  }
                  d = (u_char *)a;
                  *cp++ = digits[*d >> 4];
                  *cp++ = digits[*d++ & 0xf];
                  *cp++ = digits[*d >> 4];
                  *cp++ = digits[*d & 0xf];
                  *cp++ = ':';
                  a++;
          }
          *--cp = 0;
          return(ip6buf[ip6round]);
  }
  
  int
  in6_localaddr(in6)
          struct in6_addr *in6;
  {
          struct in6_ifaddr *ia;
  
          if (IN6_IS_ADDR_LOOPBACK(in6) || IN6_IS_ADDR_LINKLOCAL(in6))
                  return 1;
  
          for (ia = in6_ifaddr; ia; ia = ia->ia_next)
                  if (IN6_ARE_MASKED_ADDR_EQUAL(in6, &ia->ia_addr.sin6_addr,
                                                &ia->ia_prefixmask.sin6_addr))
                          return 1;
  
          return (0);
  }
  
  int
  in6_is_addr_deprecated(sa6)
          struct sockaddr_in6 *sa6;
  {
          struct in6_ifaddr *ia;
  
          for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                  if (IN6_ARE_ADDR_EQUAL(&ia->ia_addr.sin6_addr,
                                         &sa6->sin6_addr) &&
  #ifdef SCOPEDROUTING
                      ia->ia_addr.sin6_scope_id == sa6->sin6_scope_id &&
  #endif
                      (ia->ia6_flags & IN6_IFF_DEPRECATED) != 0)
                          return(1); /* true */
  
                  /* XXX: do we still have to go thru the rest of the list? */
          }
  
          return(0);              /* false */
  }
  
  /*
   * return length of part which dst and src are equal
   * hard coding...
   */
  int
  in6_matchlen(src, dst)
  struct in6_addr *src, *dst;
  {
          int match = 0;
          u_char *s = (u_char *)src, *d = (u_char *)dst;
          u_char *lim = s + 16, r;
  
          while (s < lim)
                  if ((r = (*d++ ^ *s++)) != 0) {
                          while (r < 128) {
                                  match++;
                                  r <<= 1;
                          }
                          break;
                  } else
                          match += 8;
          return match;
  }
  
  /* XXX: to be scope conscious */
  int
  in6_are_prefix_equal(p1, p2, len)
          struct in6_addr *p1, *p2;
          int len;
  {
          int bytelen, bitlen;
  
          /* sanity check */
          if (0 > len || len > 128) {
                  log(LOG_ERR, "in6_are_prefix_equal: invalid prefix length(%d)\n",
                      len);
                  return(0);
          }
  
          bytelen = len / 8;
          bitlen = len % 8;
  
          if (bcmp(&p1->s6_addr, &p2->s6_addr, bytelen))
                  return(0);
          if (p1->s6_addr[bytelen] >> (8 - bitlen) !=
              p2->s6_addr[bytelen] >> (8 - bitlen))
                  return(0);
  
          return(1);
  }
  
  void
  in6_prefixlen2mask(maskp, len)
          struct in6_addr *maskp;
          int len;
  {
          u_char maskarray[8] = {0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};
          int bytelen, bitlen, i;
  
          /* sanity check */
          if (0 > len || len > 128) {
                  log(LOG_ERR, "in6_prefixlen2mask: invalid prefix length(%d)\n",
                      len);
                  return;
          }
  
          bzero(maskp, sizeof(*maskp));
          bytelen = len / 8;
          bitlen = len % 8;
          for (i = 0; i < bytelen; i++)
                  maskp->s6_addr[i] = 0xff;
          if (bitlen)
                  maskp->s6_addr[bytelen] = maskarray[bitlen - 1];
  }
  
  /*
   * return the best address out of the same scope
   */
  struct in6_ifaddr *
  in6_ifawithscope(oifp, dst)
          struct ifnet *oifp;
          struct in6_addr *dst;
  {
          int dst_scope = in6_addrscope(dst), src_scope, best_scope = 0;
          int blen = -1;
          struct ifaddr *ifa;
          struct ifnet *ifp;
          struct in6_ifaddr *ifa_best = NULL;
          
          if (oifp == NULL) {
  #if 0
                  printf("in6_ifawithscope: output interface is not specified\n");
  #endif
                  return(NULL);
          }
  
          /*
           * We search for all addresses on all interfaces from the beginning.
           * Comparing an interface with the outgoing interface will be done
           * only at the final stage of tiebreaking.
           */
          for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
          {
                  /*
                   * We can never take an address that breaks the scope zone
                   * of the destination.
                   */
                  if (in6_addr2scopeid(ifp, dst) != in6_addr2scopeid(oifp, dst))
                          continue;
  
                  TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
                  {
                          int tlen = -1, dscopecmp, bscopecmp, matchcmp;
  
                          if (ifa->ifa_addr->sa_family != AF_INET6)
                                  continue;
  
                          src_scope = in6_addrscope(IFA_IN6(ifa));
  
                          /*
                           * Don't use an address before completing DAD
                           * nor a duplicated address.
                           */
                          if (((struct in6_ifaddr *)ifa)->ia6_flags &
                              IN6_IFF_NOTREADY)
                                  continue;
  
                          /* XXX: is there any case to allow anycasts? */
                          if (((struct in6_ifaddr *)ifa)->ia6_flags &
                              IN6_IFF_ANYCAST)
                                  continue;
  
                          if (((struct in6_ifaddr *)ifa)->ia6_flags &
                              IN6_IFF_DETACHED)
                                  continue;
  
                          /*
                           * If this is the first address we find,
                           * keep it anyway.
                           */
                          if (ifa_best == NULL)
                                  goto replace;
  
                          /*
                           * ifa_best is never NULL beyond this line except
                           * within the block labeled "replace".
                           */
  
                          /*
                           * If ifa_best has a smaller scope than dst and
                           * the current address has a larger one than
                           * (or equal to) dst, always replace ifa_best.
                           * Also, if the current address has a smaller scope
                           * than dst, ignore it unless ifa_best also has a
                           * smaller scope.
                           * Consequently, after the two if-clause below,
                           * the followings must be satisfied:
                           * (scope(src) < scope(dst) &&
                           *  scope(best) < scope(dst))
                           *  OR
                           * (scope(best) >= scope(dst) &&
                           *  scope(src) >= scope(dst))
                           */
                          if (IN6_ARE_SCOPE_CMP(best_scope, dst_scope) < 0 &&
                              IN6_ARE_SCOPE_CMP(src_scope, dst_scope) >= 0)
                                  goto replace; /* (A) */
                          if (IN6_ARE_SCOPE_CMP(src_scope, dst_scope) < 0 &&
                              IN6_ARE_SCOPE_CMP(best_scope, dst_scope) >= 0)
                                  continue; /* (B) */
  
                          /*
                           * A deprecated address SHOULD NOT be used in new
                           * communications if an alternate (non-deprecated)
                           * address is available and has sufficient scope.
                           * RFC 2462, Section 5.5.4.
                           */
                          if (((struct in6_ifaddr *)ifa)->ia6_flags &
                              IN6_IFF_DEPRECATED) {
                                  /*
                                   * Ignore any deprecated addresses if
                                   * specified by configuration.
                                   */
                                  if (!ip6_use_deprecated)
                                          continue;
  
                                  /*
                                   * If we have already found a non-deprecated
                                   * candidate, just ignore deprecated addresses.
                                   */
                                  if ((ifa_best->ia6_flags & IN6_IFF_DEPRECATED)
                                      == 0)
                                          continue;
                          }
  
                          /*
                           * A non-deprecated address is always preferred
                           * to a deprecated one regardless of scopes and
                           * address matching (Note invariants ensured by the
                           * conditions (A) and (B) above.)
                           */
                          if ((ifa_best->ia6_flags & IN6_IFF_DEPRECATED) &&
                              (((struct in6_ifaddr *)ifa)->ia6_flags &
                               IN6_IFF_DEPRECATED) == 0)
                                  goto replace;
  
                          /*
                           * When we use temporary addresses described in
                           * RFC 3041, we prefer temporary addresses to
                           * public autoconf addresses.  Again, note the
                           * invariants from (A) and (B).  Also note that we
                           * don't have any preference between static addresses
                           * and autoconf addresses (despite of whether or not
                           * the latter is temporary or public.)
                           */
                          if (ip6_use_tempaddr) {
                                  struct in6_ifaddr *ifat;
  
                                  ifat = (struct in6_ifaddr *)ifa;
                                  if ((ifa_best->ia6_flags &
                                       (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                       == IN6_IFF_AUTOCONF &&
                                      (ifat->ia6_flags &
                                       (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                       == (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY)) {
                                          goto replace;
                                  }
                                  if ((ifa_best->ia6_flags &
                                       (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                      == (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY) &&
                                      (ifat->ia6_flags &
                                       (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                       == IN6_IFF_AUTOCONF) {
                                          continue;
                                  }
                          }
  
                          /*
                           * At this point, we have two cases:
                           * 1. we are looking at a non-deprecated address,
                           *    and ifa_best is also non-deprecated.
                           * 2. we are looking at a deprecated address,
                           *    and ifa_best is also deprecated.
                           * Also, we do not have to consider a case where
                           * the scope of if_best is larger(smaller) than dst and
                           * the scope of the current address is smaller(larger)
                           * than dst. Such a case has already been covered.
                           * Tiebreaking is done according to the following
                           * items:
                           * - the scope comparison between the address and
                           *   dst (dscopecmp)
                           * - the scope comparison between the address and
                           *   ifa_best (bscopecmp)
                           * - if the address match dst longer than ifa_best
                           *   (matchcmp)
                           * - if the address is on the outgoing I/F (outI/F)
                           *
                           * Roughly speaking, the selection policy is
                           * - the most important item is scope. The same scope
                           *   is best. Then search for a larger scope.
                           *   Smaller scopes are the last resort.
                           * - A deprecated address is chosen only when we have
                           *   no address that has an enough scope, but is
                           *   prefered to any addresses of smaller scopes
                           *   (this must be already done above.)
                           * - addresses on the outgoing I/F are preferred to
                           *   ones on other interfaces if none of above
                           *   tiebreaks.  In the table below, the column "bI"
                           *   means if the best_ifa is on the outgoing
                           *   interface, and the column "sI" means if the ifa
                           *   is on the outgoing interface.
                           * - If there is no other reasons to choose one,
                           *   longest address match against dst is considered.
                           *
                           * The precise decision table is as follows:
                           * dscopecmp bscopecmp    match  bI oI | replace?
                           *       N/A     equal      N/A   Y  N |   No (1)
                           *       N/A     equal      N/A   N  Y |  Yes (2)
                           *       N/A     equal   larger    N/A |  Yes (3)
                           *       N/A     equal  !larger    N/A |   No (4)
                           *    larger    larger      N/A    N/A |   No (5)
                           *    larger   smaller      N/A    N/A |  Yes (6)
                           *   smaller    larger      N/A    N/A |  Yes (7)
                           *   smaller   smaller      N/A    N/A |   No (8)
                           *     equal   smaller      N/A    N/A |  Yes (9)
                           *     equal    larger       (already done at A above)
                           */
                          dscopecmp = IN6_ARE_SCOPE_CMP(src_scope, dst_scope);
                          bscopecmp = IN6_ARE_SCOPE_CMP(src_scope, best_scope);
  
                          if (bscopecmp == 0) {
                                  struct ifnet *bifp = ifa_best->ia_ifp;
  
                                  if (bifp == oifp && ifp != oifp) /* (1) */
                                          continue;
                                  if (bifp != oifp && ifp == oifp) /* (2) */
                                          goto replace;
  
                                  /*
                                   * Both bifp and ifp are on the outgoing
                                   * interface, or both two are on a different
                                   * interface from the outgoing I/F.
                                   * now we need address matching against dst
                                   * for tiebreaking.
                                   */
                                  tlen = in6_matchlen(IFA_IN6(ifa), dst);
                                  matchcmp = tlen - blen;
                                  if (matchcmp > 0) /* (3) */
                                          goto replace;
                                  continue; /* (4) */
                          }
                          if (dscopecmp > 0) {
                                  if (bscopecmp > 0) /* (5) */
                                          continue;
                                  goto replace; /* (6) */
                          }
                          if (dscopecmp < 0) {
                                  if (bscopecmp > 0) /* (7) */
                                          goto replace;
                                  continue; /* (8) */
                          }
  
                          /* now dscopecmp must be 0 */
                          if (bscopecmp < 0)
                                  goto replace; /* (9) */
  
                    replace:
                          ifa_best = (struct in6_ifaddr *)ifa;
                          blen = tlen >= 0 ? tlen :
                                  in6_matchlen(IFA_IN6(ifa), dst);
                          best_scope = in6_addrscope(&ifa_best->ia_addr.sin6_addr);
                  }
          }
  
          /* count statistics for future improvements */
          if (ifa_best == NULL)
                  ip6stat.ip6s_sources_none++;
          else {
                  if (oifp == ifa_best->ia_ifp)
                          ip6stat.ip6s_sources_sameif[best_scope]++;
                  else
                          ip6stat.ip6s_sources_otherif[best_scope]++;
  
                  if (best_scope == dst_scope)
                          ip6stat.ip6s_sources_samescope[best_scope]++;
                  else
                          ip6stat.ip6s_sources_otherscope[best_scope]++;
  
                  if ((ifa_best->ia6_flags & IN6_IFF_DEPRECATED) != 0)
                          ip6stat.ip6s_sources_deprecated[best_scope]++;
          }
  
          return(ifa_best);
  }
  
  /*
   * return the best address out of the same scope. if no address was
   * found, return the first valid address from designated IF.
   */
  struct in6_ifaddr *
  in6_ifawithifp(ifp, dst)
          struct ifnet *ifp;
          struct in6_addr *dst;
  {
          int dst_scope = in6_addrscope(dst), blen = -1, tlen;
          struct ifaddr *ifa;
          struct in6_ifaddr *besta = 0;
          struct in6_ifaddr *dep[2];      /* last-resort: deprecated */
  
          dep[0] = dep[1] = NULL;
  
          /*
           * We first look for addresses in the same scope.
           * If there is one, return it.
           * If two or more, return one which matches the dst longest.
           * If none, return one of global addresses assigned other ifs.
           */
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_ANYCAST)
                          continue; /* XXX: is there any case to allow anycast? */
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_NOTREADY)
                          continue; /* don't use this interface */
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DETACHED)
                          continue;
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DEPRECATED) {
                          if (ip6_use_deprecated)
                                  dep[0] = (struct in6_ifaddr *)ifa;
                          continue;
                  }
  
                  if (dst_scope == in6_addrscope(IFA_IN6(ifa))) {
                          /*
                           * call in6_matchlen() as few as possible
                           */
                          if (besta) {
                                  if (blen == -1)
                                          blen = in6_matchlen(&besta->ia_addr.sin6_addr, dst);
                                  tlen = in6_matchlen(IFA_IN6(ifa), dst);
                                  if (tlen > blen) {
                                          blen = tlen;
                                          besta = (struct in6_ifaddr *)ifa;
                                  }
                          } else
                                  besta = (struct in6_ifaddr *)ifa;
                  }
          }
          if (besta)
                  return(besta);
  
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_ANYCAST)
                          continue; /* XXX: is there any case to allow anycast? */
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_NOTREADY)
                          continue; /* don't use this interface */
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DETACHED)
                          continue;
                  if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DEPRECATED) {
                          if (ip6_use_deprecated)
                                  dep[1] = (struct in6_ifaddr *)ifa;
                          continue;
                  }
  
                  return (struct in6_ifaddr *)ifa;
          }
  
          /* use the last-resort values, that are, deprecated addresses */
          if (dep[0])
                  return dep[0];
          if (dep[1])
                  return dep[1];
  
          return NULL;
  }
  
  /*
   * perform DAD when interface becomes IFF_UP.
   */
  void
  in6_if_up(ifp)
          struct ifnet *ifp;
  {
          struct ifaddr *ifa;
          struct in6_ifaddr *ia;
          int dad_delay;          /* delay ticks before DAD output */
  
          /*
           * special cases, like 6to4, are handled in in6_ifattach
           */
          in6_ifattach(ifp, NULL);
  
          dad_delay = 0;
          TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
          {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  ia = (struct in6_ifaddr *)ifa;
                  if (ia->ia6_flags & IN6_IFF_TENTATIVE)
                          nd6_dad_start(ifa, &dad_delay);
          }
  }
  
  int
  in6if_do_dad(ifp)
          struct ifnet *ifp;
  {
          if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                  return(0);
  
          switch (ifp->if_type) {
  #ifdef IFT_DUMMY
          case IFT_DUMMY:
  #endif
          case IFT_FAITH:
                  /*
                   * These interfaces do not have the IFF_LOOPBACK flag,
                   * but loop packets back.  We do not have to do DAD on such
                   * interfaces.  We should even omit it, because loop-backed
                   * NS would confuse the DAD procedure.
                   */
                  return(0);
          default:
                  /*
                   * Our DAD routine requires the interface up and running.
                   * However, some interfaces can be up before the RUNNING
                   * status.  Additionaly, users may try to assign addresses
                   * before the interface becomes up (or running).
                   * We simply skip DAD in such a case as a work around.
                   * XXX: we should rather mark "tentative" on such addresses,
                   * and do DAD after the interface becomes ready.
                   */
                  if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) !=
                      (IFF_UP|IFF_RUNNING))
                          return(0);
  
                  return(1);
          }
  }
  
  /*
   * Calculate max IPv6 MTU through all the interfaces and store it
   * to in6_maxmtu.
   */
  void
  in6_setmaxmtu()
  {
          unsigned long maxmtu = 0;
          struct ifnet *ifp;
  
          for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
          {
                  if ((ifp->if_flags & IFF_LOOPBACK) == 0 &&
                      nd_ifinfo[ifp->if_index].linkmtu > maxmtu)
                          maxmtu =  nd_ifinfo[ifp->if_index].linkmtu;
          }
          if (maxmtu)     /* update only when maxmtu is positive */
                  in6_maxmtu = maxmtu;
  }
  
  /*
   * Convert sockaddr_in6 to sockaddr_in.  Original sockaddr_in6 must be
   * v4 mapped addr or v4 compat addr
   */
  void
  in6_sin6_2_sin(struct sockaddr_in *sin, struct sockaddr_in6 *sin6)
  {
          bzero(sin, sizeof(*sin));
          sin->sin_len = sizeof(struct sockaddr_in);
          sin->sin_family = AF_INET;
          sin->sin_port = sin6->sin6_port;
          sin->sin_addr.s_addr = sin6->sin6_addr.s6_addr32[3];    
  }
  
  /* Convert sockaddr_in to sockaddr_in6 in v4 mapped addr format. */
  void
  in6_sin_2_v4mapsin6(struct sockaddr_in *sin, struct sockaddr_in6 *sin6)
  {
          bzero(sin6, sizeof(*sin6));
          sin6->sin6_len = sizeof(struct sockaddr_in6);
          sin6->sin6_family = AF_INET6;
          sin6->sin6_port = sin->sin_port;
          sin6->sin6_addr.s6_addr32[0] = 0;
          sin6->sin6_addr.s6_addr32[1] = 0;
          sin6->sin6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
          sin6->sin6_addr.s6_addr32[3] = sin->sin_addr.s_addr;
  }
  
  /* Convert sockaddr_in6 into sockaddr_in. */
  void
  in6_sin6_2_sin_in_sock(struct sockaddr *nam)
  {
          struct sockaddr_in *sin_p;
          struct sockaddr_in6 sin6;
  
          /*
           * Save original sockaddr_in6 addr and convert it
           * to sockaddr_in.
           */
          sin6 = *(struct sockaddr_in6 *)nam;
          sin_p = (struct sockaddr_in *)nam;
          in6_sin6_2_sin(sin_p, &sin6);
  }
  
  /* Convert sockaddr_in into sockaddr_in6 in v4 mapped addr format. */
  void
  in6_sin_2_v4mapsin6_in_sock(struct sockaddr **nam)
  {
          struct sockaddr_in *sin_p;
          struct sockaddr_in6 *sin6_p;
  
          MALLOC(sin6_p, struct sockaddr_in6 *, sizeof *sin6_p, M_SONAME,
                 M_WAITOK);
          sin_p = (struct sockaddr_in *)*nam;
          in6_sin_2_v4mapsin6(sin_p, sin6_p);
          FREE(*nam, M_SONAME);
          *nam = (struct sockaddr *)sin6_p;
  }

Cache object: 98d04c0756dacbab92875c9e3e846134