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

     /*      $NetBSD: in6.c,v 1.141 2008/07/31 18:24:07 matt Exp $   */
     /*      $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $   */
     
     /*
      * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the project nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /*
     * 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. 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 <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.141 2008/07/31 18:24:07 matt Exp $");
    
    #include "opt_inet.h"
    #include "opt_pfil_hooks.h"
    
    #include <sys/param.h>
    #include <sys/ioctl.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 <sys/kauth.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 <net/if_ether.h>
    
    #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>
   
   #include <net/net_osdep.h>
   
   #ifdef PFIL_HOOKS
   #include <net/pfil.h>
   #endif
   
   MALLOC_DEFINE(M_IP6OPT, "ip6_options", "IPv6 options");
   
   /* enable backward compatibility code for obsoleted ioctls */
   #define COMPAT_IN6IFIOCTL
   
   #ifdef  IN6_DEBUG
   #define IN6_DPRINTF(__fmt, ...) printf(__fmt, __VA_ARGS__)
   #else
   #define IN6_DPRINTF(__fmt, ...) do { } while (/*CONSTCOND*/0) 
   #endif /* IN6_DEBUG */
   
   /*
    * Definitions of some constant 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(struct socket *, u_long, void *,
           struct ifnet *, struct lwp *);
   static int in6_ifinit(struct ifnet *, struct in6_ifaddr *,
           struct sockaddr_in6 *, int);
   static void in6_unlink_ifa(struct in6_ifaddr *, struct ifnet *);
   
   /*
    * 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 lo_sa;
           struct sockaddr_in6 all1_sa;
           struct rtentry *nrt = NULL;
           int e;
   
           sockaddr_in6_init(&all1_sa, &in6mask128, 0, 0, 0);
           sockaddr_in6_init(&lo_sa, &in6addr_loopback, 0, 0, 0);
   
           /*
            * 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)
                   rt_replace_ifa(nrt, 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.
    */
   void
   in6_ifaddloop(struct ifaddr *ifa)
   {
           struct rtentry *rt;
   
           /* If there is no loopback entry, allocate one. */
           rt = rtalloc1(ifa->ifa_addr, 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 != NULL)
                   rt->rt_refcnt--;
   }
   
   /*
    * Remove loopback rtentry of ownaddr generated by in6_ifaddloop(),
    * if it exists.
    */
   void
   in6_ifremloop(struct ifaddr *ifa)
   {
           struct in6_ifaddr *alt_ia = NULL, *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.
            */
   
           /*
            * Delete the entry only if exactly one ifaddr matches the
            * address, ifa->ifa_addr.
            *
            * If more than one ifaddr matches, replace the ifaddr in
            * the routing table, rt_ifa, with a different ifaddr than
            * the one we are purging, ifa.  It is important to do
            * this, or else the routing table can accumulate dangling
            * pointers rt->rt_ifa->ifa_ifp to destroyed interfaces,
            * which will lead to crashes, later.  (More than one ifaddr
            * can match if we assign the same address to multiple---probably
            * p2p---interfaces.)
            *
            * XXX An old comment at this place said, "we should avoid
            * XXX such a configuration [i.e., interfaces with the same
            * XXX addressed assigned --ed.] in IPv6...".  I do not
            * XXX agree, especially now that I have fixed the dangling
            * XXX ifp-pointers bug.
            */
           for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                   if (!IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &ia->ia_addr.sin6_addr))
                           continue;
                   if (ia->ia_ifp != ifa->ifa_ifp)
                           alt_ia = ia;
                   if (++ia_count > 1 && alt_ia != NULL)
                           break;
           }
   
           if (ia_count == 0)
                   return;
   
           if ((rt = rtalloc1(ifa->ifa_addr, 0)) == NULL)
                   return;
           rt->rt_refcnt--;
   
           /*
            * Before deleting, check if a corresponding loopbacked
            * host route surely exists.  With this check, we can avoid
            * deleting an interface direct route whose destination is
            * the same as the address being removed.  This can happen
            * when removing a subnet-router anycast address on an
            * interface attached to a shared medium.
            */
           if ((rt->rt_flags & RTF_HOST) == 0 ||
               (rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0)
                   return;
   
           /* If we cannot replace the route's ifaddr with the equivalent
            * ifaddr of another interface, I believe it is safest to
            * delete the route.
            */
           if (ia_count == 1 || alt_ia == NULL)
                   in6_ifloop_request(RTM_DELETE, ifa);
           else
                   rt_replace_ifa(rt, &alt_ia->ia_ifa);
   }
   
   int
   in6_mask2len(struct in6_addr *mask, u_char *lim0)
   {
           int x = 0, y;
           u_char *lim = lim0, *p;
   
           /* ignore the scope_id part */
           if (lim0 == NULL || lim0 - (u_char *)mask > sizeof(*mask))
                   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 < NBBY; 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 * NBBY + y;
   }
   
   #define ifa2ia6(ifa)    ((struct in6_ifaddr *)(ifa))
   #define ia62ifa(ia6)    (&((ia6)->ia_ifa))
   
   static int
   in6_control1(struct socket *so, u_long cmd, void *data, struct ifnet *ifp,
       struct lwp *l, int privileged)
   {
           struct  in6_ifreq *ifr = (struct in6_ifreq *)data;
           struct  in6_ifaddr *ia = NULL;
           struct  in6_aliasreq *ifra = (struct in6_aliasreq *)data;
           struct sockaddr_in6 *sa6;
           int error;
           switch (cmd) {
           /*
            * XXX: Fix me, once we fix SIOCSIFADDR, SIOCIFDSTADDR, etc.
            */
           case SIOCSIFADDR:
           case SIOCSIFDSTADDR:
   #ifdef SIOCSIFCONF_X25
           case SIOCSIFCONF_X25:
   #endif
                   return EOPNOTSUPP;
           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:
           case SIOCSIFINFO_IN6:
                   if (!privileged)
                           return EPERM;
                   /* FALLTHROUGH */
           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 SIOCALIFADDR:
           case SIOCDLIFADDR:
                   if (!privileged)
                           return EPERM;
                   /* FALLTHROUGH */
           case SIOCGLIFADDR:
                   return in6_lifaddr_ioctl(so, cmd, data, ifp, l);
           }
   
           /*
            * Find address for this interface, if it exists.
            *
            * In netinet code, we have checked ifra_addr in SIOCSIF*ADDR operation
            * only, and used the first interface address as the target of other
            * operations (without checking ifra_addr).  This was because netinet
            * code/API assumed at most 1 interface address per interface.
            * Since IPv6 allows a node to assign multiple addresses
            * on a single interface, we almost always look and check the
            * presence of ifra_addr, and reject invalid ones here.
            * It also decreases duplicated code among SIOC*_IN6 operations.
            */
           switch (cmd) {
           case SIOCAIFADDR_IN6:
           case SIOCSIFPHYADDR_IN6:
                   sa6 = &ifra->ifra_addr;
                   break;
           case SIOCSIFADDR_IN6:
           case SIOCGIFADDR_IN6:
           case SIOCSIFDSTADDR_IN6:
           case SIOCSIFNETMASK_IN6:
           case SIOCGIFDSTADDR_IN6:
           case SIOCGIFNETMASK_IN6:
           case SIOCDIFADDR_IN6:
           case SIOCGIFPSRCADDR_IN6:
           case SIOCGIFPDSTADDR_IN6:
           case SIOCGIFAFLAG_IN6:
           case SIOCSNDFLUSH_IN6:
           case SIOCSPFXFLUSH_IN6:
           case SIOCSRTRFLUSH_IN6:
           case SIOCGIFALIFETIME_IN6:
           case SIOCGIFSTAT_IN6:
           case SIOCGIFSTAT_ICMP6:
                   sa6 = &ifr->ifr_addr;
                   break;
           default:
                   sa6 = NULL;
                   break;
           }
           if (sa6 && sa6->sin6_family == AF_INET6) {
                   if (sa6->sin6_scope_id != 0)
                           error = sa6_embedscope(sa6, 0);
                   else
                           error = in6_setscope(&sa6->sin6_addr, ifp, NULL);
                   if (error != 0)
                           return error;
                   ia = in6ifa_ifpwithaddr(ifp, &sa6->sin6_addr);
           } else
                   ia = NULL;
   
           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 deprecated.
                    */
                   return EINVAL;
   
           case SIOCDIFADDR_IN6:
                   /*
                    * for IPv4, we look for existing in_ifaddr here to allow
                    * "ifconfig if0 delete" to remove the first IPv4 address on
                    * the interface.  For IPv6, as the spec allows 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. */
                   /* FALLTHROUGH */
           case SIOCGIFAFLAG_IN6:
           case SIOCGIFNETMASK_IN6:
           case SIOCGIFDSTADDR_IN6:
           case SIOCGIFALIFETIME_IN6:
                   /* must think again about its semantics */
                   if (ia == NULL)
                           return EADDRNOTAVAIL;
                   break;
           }
   
           switch (cmd) {
   
           case SIOCGIFADDR_IN6:
                   ifr->ifr_addr = ia->ia_addr;
                   if ((error = sa6_recoverscope(&ifr->ifr_addr)) != 0)
                           return error;
                   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;
                   if ((error = sa6_recoverscope(&ifr->ifr_dstaddr)) != 0)
                           return error;
                   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;
                   bzero(&ifr->ifr_ifru.ifru_stat,
                       sizeof(ifr->ifr_ifru.ifru_stat));
                   ifr->ifr_ifru.ifru_stat =
                       *((struct in6_ifextra *)ifp->if_afdata[AF_INET6])->in6_ifstat;
                   break;
   
           case SIOCGIFSTAT_ICMP6:
                   if (ifp == NULL)
                           return EINVAL;
                   bzero(&ifr->ifr_ifru.ifru_icmp6stat,
                       sizeof(ifr->ifr_ifru.ifru_icmp6stat));
                   ifr->ifr_ifru.ifru_icmp6stat =
                       *((struct in6_ifextra *)ifp->if_afdata[AF_INET6])->icmp6_ifstat;
                   break;
   
           case SIOCGIFALIFETIME_IN6:
                   ifr->ifr_ifru.ifru_lifetime = ia->ia6_lifetime;
                   if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                           time_t maxexpire;
                           struct in6_addrlifetime *retlt =
                               &ifr->ifr_ifru.ifru_lifetime;
   
                           /*
                            * XXX: adjust expiration time assuming time_t is
                            * signed.
                            */
                           maxexpire = ((time_t)~0) &
                               ~((time_t)1 << ((sizeof(maxexpire) * NBBY) - 1));
                           if (ia->ia6_lifetime.ia6t_vltime <
                               maxexpire - ia->ia6_updatetime) {
                                   retlt->ia6t_expire = ia->ia6_updatetime +
                                       ia->ia6_lifetime.ia6t_vltime;
                           } else
                                   retlt->ia6t_expire = maxexpire;
                   }
                   if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                           time_t maxexpire;
                           struct in6_addrlifetime *retlt =
                               &ifr->ifr_ifru.ifru_lifetime;
   
                           /*
                            * XXX: adjust expiration time assuming time_t is
                            * signed.
                            */
                           maxexpire = ((time_t)~0) &
                               ~((time_t)1 << ((sizeof(maxexpire) * NBBY) - 1));
                           if (ia->ia6_lifetime.ia6t_pltime <
                               maxexpire - ia->ia6_updatetime) {
                                   retlt->ia6t_preferred = ia->ia6_updatetime +
                                       ia->ia6_lifetime.ia6t_pltime;
                           } else
                                   retlt->ia6t_preferred = maxexpire;
                   }
                   break;
   
           case SIOCAIFADDR_IN6:
           {
                   int i;
                   struct nd_prefixctl pr0;
                   struct nd_prefix *pr;
   
                   /* reject read-only flags */
                   if ((ifra->ifra_flags & IN6_IFF_DUPLICATED) != 0 ||
                       (ifra->ifra_flags & IN6_IFF_DETACHED) != 0 ||
                       (ifra->ifra_flags & IN6_IFF_NODAD) != 0 ||
                       (ifra->ifra_flags & IN6_IFF_AUTOCONF) != 0) {
                           return EINVAL;
                   }
                   /*
                    * first, make or update the interface address structure,
                    * and link it to the list.
                    */
                   if ((error = in6_update_ifa(ifp, ifra, ia, 0)) != 0)
                           return error;
                   if ((ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr))
                       == NULL) {
                           /*
                            * this can happen when the user specify the 0 valid
                            * lifetime.
                            */
                           break;
                   }
   
                   /*
                    * 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;
                   /* 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 not yet. */
                   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 succeeded but "
                                       "no prefix\n");
                                   return EINVAL; /* XXX panic here? */
                           }
                   }
   
                   /* relate the address to the prefix */
                   if (ia->ia6_ndpr == NULL) {
                           ia->ia6_ndpr = pr;
                           pr->ndpr_refcnt++;
   
                           /*
                            * If this is the first autoconf address from the
                            * prefix, create a temporary address as well
                            * (when required).
                            */
                           if ((ia->ia6_flags & IN6_IFF_AUTOCONF) &&
                               ip6_use_tempaddr && pr->ndpr_refcnt == 1) {
                                   int e;
                                   if ((e = in6_tmpifadd(ia, 1, 0)) != 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();
   
   #ifdef PFIL_HOOKS
                   (void)pfil_run_hooks(&if_pfil, (struct mbuf **)SIOCAIFADDR_IN6,
                       ifp, PFIL_IFADDR);
   #endif
   
                   break;
           }
   
           case SIOCDIFADDR_IN6:
           {
                   struct nd_prefix *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 worry 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.
                    * Note that in6_purgeaddr() will decrement ndpr_refcnt.
                    */
                   pr = ia->ia6_ndpr;
                   in6_purgeaddr(&ia->ia_ifa);
                   if (pr && pr->ndpr_refcnt == 0)
                           prelist_remove(pr);
   #ifdef PFIL_HOOKS
                   (void)pfil_run_hooks(&if_pfil, (struct mbuf **)SIOCDIFADDR_IN6,
                       ifp, PFIL_IFADDR);
   #endif
                   break;
           }
   
           default:
                   if (ifp == NULL || ifp->if_ioctl == 0)
                           return EOPNOTSUPP;
                   error = ((*ifp->if_ioctl)(ifp, cmd, data));
                   return error;
           }
   
           return 0;
   }
   
   int
   in6_control(struct socket *so, u_long cmd, void *data, struct ifnet *ifp,
       struct lwp *l)
   {
           int error, privileged, s;
   
           privileged = 0;
           if (l && !kauth_authorize_generic(l->l_cred,
               KAUTH_GENERIC_ISSUSER, NULL))
                   privileged++;
   
           s = splnet();
           error = in6_control1(so , cmd, data, ifp, l, privileged);
           splx(s);
           return error;
   }
   
   /*
    * 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()?
    */
   static int
   in6_update_ifa1(struct ifnet *ifp, struct in6_aliasreq *ifra,
       struct in6_ifaddr *ia, int flags)
   {
           int error = 0, hostIsNew = 0, plen = -1;
           struct in6_ifaddr *oia;
           struct sockaddr_in6 dst6;
           struct in6_addrlifetime *lt;
           struct in6_multi_mship *imm;
           struct in6_multi *in6m_sol;
           struct rtentry *rt;
           int dad_delay;
   
           in6m_sol = NULL;
   
           /* 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)) != 0 &&
               (dst6.sin6_family == AF_INET6)) {
                   struct in6_addr in6_tmp;
                   u_int32_t zoneid;
   
                   in6_tmp = dst6.sin6_addr;
                   if (in6_setscope(&in6_tmp, ifp, &zoneid))
                           return EINVAL; /* XXX: should be impossible */
   
                   if (dst6.sin6_scope_id != 0) {
                           if (dst6.sin6_scope_id != zoneid)
                                   return EINVAL;
                   } else          /* user omit to specify the ID. */
                           dst6.sin6_scope_id = zoneid;
   
                   /* convert into the internal form */
                   if (sa6_embedscope(&dst6, 0))
                           return EINVAL; /* XXX: should be impossible */
           }
           /*
            * 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) {
   #ifdef FORCE_P2PPLEN
                   int i;
   #endif
   
                   if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) == 0) {
                           /* XXX: noisy message */
                           nd6log((LOG_INFO, "in6_update_ifa: a destination can "
                               "be specified for a p2p or a loopback IF only\n"));
                           return EINVAL;
                   }
                   if (plen != 128) {
                           nd6log((LOG_INFO, "in6_update_ifa: prefixlen should "
                               "be 128 when dstaddr is specified\n"));
   #ifdef FORCE_P2PPLEN
                           /*
                            * To be compatible with old configurations,
                            * such as ifconfig gif0 inet6 2001::1 2001::2
                            * prefixlen 126, we override the specified
                            * prefixmask as if the prefix length was 128.
                            */
                           ifra->ifra_prefixmask.sin6_len =
                               sizeof(struct sockaddr_in6);
                           for (i = 0; i < 4; i++)
                                   ifra->ifra_prefixmask.sin6_addr.s6_addr32[i] =
                                       0xffffffff;
                           plen = 128;
   #else
                           return EINVAL;
   #endif
                   }
           }
           /* lifetime consistency check */
           lt = &ifra->ifra_lifetime;
           if (lt->ia6t_pltime > lt->ia6t_vltime)
                   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.
                    */
                   nd6log((LOG_INFO,
                       "in6_update_ifa: valid lifetime is 0 for %s\n",
                       ip6_sprintf(&ifra->ifra_addr.sin6_addr)));
   
                   if (ia == NULL)
                           return 0; /* there's nothing to do */
           }
   
           /*
            * 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 an interrupt context.  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((void *)ia, sizeof(*ia));
                   LIST_INIT(&ia->ia6_memberships);
                   /* Initialize the address and masks, and put time stamp */
                   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);
                   ia->ia6_createtime = time_second;
                   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;
                   /* gain a refcnt for the link from in6_ifaddr */
                   IFAREF(&ia->ia_ifa);
   
                   ifa_insert(ifp, &ia->ia_ifa);
           }
   
           /* update timestamp */
           ia->ia6_updatetime = time_second;
   
           /* 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) {
                           nd6log((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)) {
                   if ((ia->ia_flags & IFA_ROUTE) != 0 &&
                       rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST) != 0) {
                           nd6log((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;
           }
   
           /*
            * Set lifetimes.  We do not refer to ia6t_expire and ia6t_preferred
            * to see if the address is deprecated or invalidated, but initialize
            * these members for applications.
            */
           ia->ia6_lifetime = ifra->ifra_lifetime;
           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;
  
          /* reset the interface and routing table appropriately. */
          if ((error = in6_ifinit(ifp, ia, &ifra->ifra_addr, hostIsNew)) != 0)
                  goto unlink;
  
          /*
           * configure address flags.
           */
          ia->ia6_flags = ifra->ifra_flags;
          /*
           * backward compatibility - if IN6_IFF_DEPRECATED is set from the
           * userland, make it deprecated.
           */
          if ((ifra->ifra_flags & IN6_IFF_DEPRECATED) != 0) {
                  ia->ia6_lifetime.ia6t_pltime = 0;
                  ia->ia6_lifetime.ia6t_preferred = time_second;
          }
  
          /*
           * Make the address tentative before joining multicast addresses,
           * so that corresponding MLD responses would not have a tentative
           * source address.
           */
          ia->ia6_flags &= ~IN6_IFF_DUPLICATED;   /* safety */
          if (hostIsNew && in6if_do_dad(ifp)) 
                  ia->ia6_flags |= IN6_IFF_TENTATIVE;
  
          /*
           * We are done if we have simply modified an existing address.
           */
          if (!hostIsNew)
                  return error;
  
          /*
           * Beyond this point, we should call in6_purgeaddr upon an error,
           * not just go to unlink.
           */
  
          /* join necessary multicast groups */
          if ((ifp->if_flags & IFF_MULTICAST) != 0) {
                  struct sockaddr_in6 mltaddr, mltmask;
                  struct in6_addr llsol;
  
                  /* join solicited multicast addr for new host id */
                  bzero(&llsol, sizeof(struct in6_addr));
                  llsol.s6_addr16[0] = htons(0xff02);
                  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;
                  if ((error = in6_setscope(&llsol, ifp, NULL)) != 0) {
                          /* XXX: should not happen */
                          log(LOG_ERR, "in6_update_ifa: "
                              "in6_setscope failed\n");
                          goto cleanup;
                  }
                  dad_delay = 0;
                  if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                          /*
                           * We need a random delay for DAD on the address
                           * being configured.  It also means delaying
                           * transmission of the corresponding MLD report to
                           * avoid report collision.
                           * [draft-ietf-ipv6-rfc2462bis-02.txt]
                           */
                          dad_delay = arc4random() %
                              (MAX_RTR_SOLICITATION_DELAY * hz);
                  }
  
  #define MLTMASK_LEN  4  /* mltmask's masklen (=32bit=4octet) */
                  /* join solicited multicast addr for new host id */
                  imm = in6_joingroup(ifp, &llsol, &error, dad_delay);
                  if (!imm) {
                          nd6log((LOG_ERR,
                              "in6_update_ifa: addmulti "
                              "failed for %s on %s (errno=%d)\n",
                              ip6_sprintf(&llsol), if_name(ifp), error));
                          goto cleanup;
                  }
                  LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
                  in6m_sol = imm->i6mm_maddr;
  
                  sockaddr_in6_init(&mltmask, &in6mask32, 0, 0, 0);
  
                  /*
                   * join link-local all-nodes address
                   */
                  sockaddr_in6_init(&mltaddr, &in6addr_linklocal_allnodes,
                      0, 0, 0);
                  if ((error = in6_setscope(&mltaddr.sin6_addr, ifp, NULL)) != 0)
                          goto cleanup; /* XXX: should not fail */
  
                  /*
                   * XXX: do we really need this automatic routes?
                   * We should probably reconsider this stuff.  Most applications
                   * actually do not need the routes, since they usually specify
                   * the outgoing interface.
                   */
                  rt = rtalloc1((struct sockaddr *)&mltaddr, 0);
                  if (rt) {
                          if (memcmp(&mltaddr.sin6_addr,
                              &satocsin6(rt_getkey(rt))->sin6_addr,
                              MLTMASK_LEN)) {
                                  RTFREE(rt);
                                  rt = NULL;
                          } else if (rt->rt_ifp != ifp) {
                                  IN6_DPRINTF("%s: rt_ifp %p -> %p (%s) "
                                      "network %04x:%04x::/32 = %04x:%04x::/32\n",
                                      __func__, rt->rt_ifp, ifp, ifp->if_xname,
                                      ntohs(mltaddr.sin6_addr.s6_addr16[0]),
                                      ntohs(mltaddr.sin6_addr.s6_addr16[1]),
                                      satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[0],
                                      satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[1]);
                                  rt_replace_ifa(rt, &ia->ia_ifa);
                                  rt->rt_ifp = ifp;
                          }
                  }
                  if (!rt) {
                          struct rt_addrinfo info;
  
                          bzero(&info, sizeof(info));
                          info.rti_info[RTAX_DST] = (struct sockaddr *)&mltaddr;
                          info.rti_info[RTAX_GATEWAY] =
                              (struct sockaddr *)&ia->ia_addr;
                          info.rti_info[RTAX_NETMASK] =
                              (struct sockaddr *)&mltmask;
                          info.rti_info[RTAX_IFA] =
                              (struct sockaddr *)&ia->ia_addr;
                          /* XXX: we need RTF_CLONING to fake nd6_rtrequest */
                          info.rti_flags = RTF_UP | RTF_CLONING;
                          error = rtrequest1(RTM_ADD, &info, NULL);
                          if (error)
                                  goto cleanup;
                  } else {
                          RTFREE(rt);
                  }
                  imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
                  if (!imm) {
                          nd6log((LOG_WARNING,
                              "in6_update_ifa: addmulti failed for "
                              "%s on %s (errno=%d)\n",
                              ip6_sprintf(&mltaddr.sin6_addr),
                              if_name(ifp), error));
                          goto cleanup;
                  }
                  LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
  
                  /*
                   * join node information group address
                   */
                  dad_delay = 0;
                  if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                          /*
                           * The spec doesn't say anything about delay for this
                           * group, but the same logic should apply.
                           */
                          dad_delay = arc4random() %
                              (MAX_RTR_SOLICITATION_DELAY * hz);
                  }
                  if (in6_nigroup(ifp, hostname, hostnamelen, &mltaddr) != 0)
                          ;
                  else if ((imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error,
                            dad_delay)) == NULL) { /* XXX jinmei */
                          nd6log((LOG_WARNING, "in6_update_ifa: "
                              "addmulti failed for %s on %s (errno=%d)\n",
                              ip6_sprintf(&mltaddr.sin6_addr),
                              if_name(ifp), error));
                          /* XXX not very fatal, go on... */
                  } else {
                          LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
                  }
  
  
                  /*
                   * join interface-local all-nodes address.
                   * (ff01::1%ifN, and ff01::%ifN/32)
                   */
                  mltaddr.sin6_addr = in6addr_nodelocal_allnodes;
                  if ((error = in6_setscope(&mltaddr.sin6_addr, ifp, NULL)) != 0) 
                          goto cleanup; /* XXX: should not fail */
  
                  /* XXX: again, do we really need the route? */
                  rt = rtalloc1((struct sockaddr *)&mltaddr, 0);
                  if (rt) {
                          /* 32bit came from "mltmask" */
                          if (memcmp(&mltaddr.sin6_addr,
                              &satocsin6(rt_getkey(rt))->sin6_addr,
                              32 / NBBY)) {
                                  RTFREE(rt);
                                  rt = NULL;
                          } else if (rt->rt_ifp != ifp) {
                                  IN6_DPRINTF("%s: rt_ifp %p -> %p (%s) "
                                      "network %04x:%04x::/32 = %04x:%04x::/32\n",
                                      __func__, rt->rt_ifp, ifp, ifp->if_xname,
                                      ntohs(mltaddr.sin6_addr.s6_addr16[0]),
                                      ntohs(mltaddr.sin6_addr.s6_addr16[1]),
                                      satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[0],
                                      satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[1]);
                                  rt_replace_ifa(rt, &ia->ia_ifa);
                                  rt->rt_ifp = ifp;
                          }
                  }
                  if (!rt) {
                          struct rt_addrinfo info;
  
                          bzero(&info, sizeof(info));
                          info.rti_info[RTAX_DST] = (struct sockaddr *)&mltaddr;
                          info.rti_info[RTAX_GATEWAY] =
                              (struct sockaddr *)&ia->ia_addr;
                          info.rti_info[RTAX_NETMASK] =
                              (struct sockaddr *)&mltmask;
                          info.rti_info[RTAX_IFA] =
                              (struct sockaddr *)&ia->ia_addr;
                          info.rti_flags = RTF_UP | RTF_CLONING;
                          error = rtrequest1(RTM_ADD, &info, NULL);
                          if (error)
                                  goto cleanup;
  #undef  MLTMASK_LEN
                  } else {
                          RTFREE(rt);
                  }
                  imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
                  if (!imm) {
                          nd6log((LOG_WARNING, "in6_update_ifa: "
                              "addmulti failed for %s on %s (errno=%d)\n",
                              ip6_sprintf(&mltaddr.sin6_addr),
                              if_name(ifp), error));
                          goto cleanup;
                  } else {
                          LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
                  }
          }
  
          /*
           * Perform DAD, if needed.
           * XXX It may be of use, if we can administratively
           * disable DAD.
           */
          if (hostIsNew && in6if_do_dad(ifp) &&
              ((ifra->ifra_flags & IN6_IFF_NODAD) == 0) &&
              (ia->ia6_flags & IN6_IFF_TENTATIVE))
          {
                  int mindelay, maxdelay;
  
                  dad_delay = 0;
                  if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                          /*
                           * We need to impose a delay before sending an NS
                           * for DAD.  Check if we also needed a delay for the
                           * corresponding MLD message.  If we did, the delay
                           * should be larger than the MLD delay (this could be
                           * relaxed a bit, but this simple logic is at least
                           * safe).
                           */
                          mindelay = 0;
                          if (in6m_sol != NULL &&
                              in6m_sol->in6m_state == MLD_REPORTPENDING) {
                                  mindelay = in6m_sol->in6m_timer;
                          }
                          maxdelay = MAX_RTR_SOLICITATION_DELAY * hz;
                          if (maxdelay - mindelay == 0)
                                  dad_delay = 0;
                          else {
                                  dad_delay =
                                      (arc4random() % (maxdelay - mindelay)) +
                                      mindelay;
                          }
                  }
                  nd6_dad_start((struct ifaddr *)ia, dad_delay);
          }
  
          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;
  
    cleanup:
          in6_purgeaddr(&ia->ia_ifa);
          return error;
  }
  
  int
  in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
      struct in6_ifaddr *ia, int flags)
  {
          int rc, s;
  
          s = splnet();
          rc = in6_update_ifa1(ifp, ifra, ia, flags);
          splx(s);
          return rc;
  }
  
  void
  in6_purgeaddr(struct ifaddr *ifa)
  {
          struct ifnet *ifp = ifa->ifa_ifp;
          struct in6_ifaddr *ia = (struct in6_ifaddr *) ifa;
          struct in6_multi_mship *imm;
  
          /* 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));
  
          /*
           * leave from multicast groups we have joined for the interface
           */
          while ((imm = LIST_FIRST(&ia->ia6_memberships)) != NULL) {
                  LIST_REMOVE(imm, i6mm_chain);
                  in6_leavegroup(imm);
          }
  
          in6_unlink_ifa(ia, ifp);
  }
  
  static void
  in6_unlink_ifa(struct in6_ifaddr *ia, struct ifnet *ifp)
  {
          struct in6_ifaddr *oia;
          int     s = splnet();
  
          ifa_remove(ifp, &ia->ia_ifa);
  
          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");
                  }
          }
  
          /*
           * XXX thorpej@NetBSD.org -- if the interface is going
           * XXX away, don't save the multicast entries, delete them!
           */
          if (LIST_EMPTY(&oia->ia6_multiaddrs))
                  ;
          else if (oia->ia_ifa.ifa_ifp->if_output == if_nulloutput) {
                  struct in6_multi *in6m, *next;
  
                  for (in6m = LIST_FIRST(&oia->ia6_multiaddrs); in6m != NULL;
                       in6m = next) {
                          next = LIST_NEXT(in6m, in6m_entry);
                          in6_delmulti(in6m);
                  }
          } else
                  in6_savemkludge(oia);
  
          /*
           * Release the reference to the base prefix.  There should be a
           * positive reference.
           */
          if (oia->ia6_ndpr == NULL) {
                  nd6log((LOG_NOTICE, "in6_unlink_ifa: autoconf'ed address "
                      "%p has no prefix\n", oia));
          } else {
                  oia->ia6_ndpr->ndpr_refcnt--;
                  oia->ia6_ndpr = NULL;
          }
  
          /*
           * Also, if the address being removed is autoconf'ed, call
           * pfxlist_onlink_check() since the release might affect the status of
           * other (detached) addresses.
           */
          if ((oia->ia6_flags & IN6_IFF_AUTOCONF) != 0)
                  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(struct ifnet *ifp)
  {
          if_purgeaddrs(ifp, AF_INET6, in6_purgeaddr);
  
          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 accommodate 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(struct socket *so, u_long cmd, void *data, 
          struct ifnet *ifp, struct lwp *l)
  {
          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");
                  /* NOTREACHED */
          }
  
          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) * NBBY < iflr->prefixlen)
                  return EINVAL;
  
          switch (cmd) {
          case SIOCALIFADDR:
              {
                  struct in6_aliasreq ifra;
                  struct in6_addr *xhostid = NULL;
                  int prefixlen;
  
                  if ((iflr->flags & IFLR_PREFIX) != 0) {
                          struct sockaddr_in6 *sin6;
  
                          /*
                           * xhostid is to fill in the hostid part of the
                           * address.  xhostid points to the first link-local
                           * address attached to the interface.
                           */
                          ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0);
                          if (!ifa)
                                  return EADDRNOTAVAIL;
                          xhostid = 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 (xhostid) {
                          /* fill in hostid part */
                          ifra.ifra_addr.sin6_addr.s6_addr32[2] =
                              xhostid->s6_addr32[2];
                          ifra.ifra_addr.sin6_addr.s6_addr32[3] =
                              xhostid->s6_addr32[3];
                  }
  
                  if (((struct sockaddr *)&iflr->dstaddr)->sa_family) { /* XXX */
                          bcopy(&iflr->dstaddr, &ifra.ifra_dstaddr,
                              ((struct sockaddr *)&iflr->dstaddr)->sa_len);
                          if (xhostid) {
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[2] =
                                      xhostid->s6_addr32[2];
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[3] =
                                      xhostid->s6_addr32[3];
                          }
                  }
  
                  ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
                  in6_prefixlen2mask(&ifra.ifra_prefixmask.sin6_addr, prefixlen);
  
                  ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
                  ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
                  ifra.ifra_flags = iflr->flags & ~IFLR_PREFIX;
                  return in6_control(so, SIOCAIFADDR_IN6, (void *)&ifra, ifp, l);
              }
          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_prefixlen2mask(&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_prefixlen2mask(&mask, 128);
                                  sin6 = (struct sockaddr_in6 *)&iflr->addr;
                                  bcopy(&sin6->sin6_addr, &match, sizeof(match));
  
                                  cmp = 1;
                          }
                  }
  
                  IFADDR_FOREACH(ifa, ifp) {
                          if (ifa->ifa_addr->sa_family != AF_INET6)
                                  continue;
                          if (!cmp)
                                  break;
  
                          /*
                           * XXX: this is adhoc, but is necessary to allow
                           * a user to specify fe80::/64 (not /10) for a
                           * link-local address.
                           */
                          bcopy(IFA_IN6(ifa), &candidate, sizeof(candidate));
                          in6_clearscope(&candidate);
                          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) {
                          int error;
  
                          /* fill in the if_laddrreq structure */
                          bcopy(&ia->ia_addr, &iflr->addr, ia->ia_addr.sin6_len);
                          error = sa6_recoverscope(
                              (struct sockaddr_in6 *)&iflr->addr);
                          if (error != 0)
                                  return error;
  
                          if ((ifp->if_flags & IFF_POINTOPOINT) != 0) {
                                  bcopy(&ia->ia_dstaddr, &iflr->dstaddr,
                                      ia->ia_dstaddr.sin6_len);
                                  error = sa6_recoverscope(
                                      (struct sockaddr_in6 *)&iflr->dstaddr);
                                  if (error != 0)
                                          return error;
                          } 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, (void *)&ifra,
                              ifp, l);
                  }
              }
          }
  
          return EOPNOTSUPP;      /* just for safety */
  }
  
  /*
   * Initialize an interface's internet6 address
   * and routing table entry.
   */
  static int
  in6_ifinit(struct ifnet *ifp, struct in6_ifaddr *ia, 
          struct sockaddr_in6 *sin6, int newhost)
  {
          int     error = 0, plen, ifacount = 0;
          int     s = splnet();
          struct ifaddr *ifa;
  
          /*
           * Give the interface a chance to initialize
           * if this is its first address,
           * and to validate the address if necessary.
           */
          IFADDR_FOREACH(ifa, ifp) {
                  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, (void *)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 the destination address is specified for a point-to-point
           * interface, install a route to the destination as an interface
           * direct route.
           */
          plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL); /* XXX */
          if (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;
          }
  
          /* 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));
          }
  
          if (ifp->if_flags & IFF_MULTICAST)
                  in6_restoremkludge(ia, ifp);
  
          return error;
  }
  
  /*
   * Find an IPv6 interface link-local address specific to an interface.
   */
  struct in6_ifaddr *
  in6ifa_ifpforlinklocal(const struct ifnet *ifp, const int ignoreflags)
  {
          struct ifaddr *ifa;
  
          IFADDR_FOREACH(ifa, ifp) {
                  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(const struct ifnet *ifp, const struct in6_addr *addr)
  {
          struct ifaddr *ifa;
  
          IFADDR_FOREACH(ifa, ifp) {
                  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;
  }
  
  /*
   * find the internet address on a given interface corresponding to a neighbor's
   * address.
   */
  struct in6_ifaddr *
  in6ifa_ifplocaladdr(const struct ifnet *ifp, const struct in6_addr *addr)
  {
          struct ifaddr *ifa;
          struct in6_ifaddr *ia;
  
          IFADDR_FOREACH(ifa, ifp) {
                  if (ifa->ifa_addr == NULL)
                          continue;       /* just for safety */
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  ia = (struct in6_ifaddr *)ifa;
                  if (IN6_ARE_MASKED_ADDR_EQUAL(addr,
                                  &ia->ia_addr.sin6_addr,
                                  &ia->ia_prefixmask.sin6_addr))
                          return ia;
          }
  
          return NULL;
  }
  
  /*
   * Convert IP6 address to printable (loggable) representation.
   */
  static int ip6round = 0;
  char *
  ip6_sprintf(const struct in6_addr *addr)
  {
          static char ip6buf[8][48];
          int i;
          char *cp;
          const u_int16_t *a = (const u_int16_t *)addr;
          const u_int8_t *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 = (const u_char *)a;
                  *cp++ = hexdigits[*d >> 4];
                  *cp++ = hexdigits[*d++ & 0xf];
                  *cp++ = hexdigits[*d >> 4];
                  *cp++ = hexdigits[*d & 0xf];
                  *cp++ = ':';
                  a++;
          }
          *--cp = 0;
          return ip6buf[ip6round];
  }
  
  /*
   * Determine if an address is on a local network.
   */
  int
  in6_localaddr(const 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(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(struct in6_addr *src, struct in6_addr *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 += NBBY;
          return match;
  }
  
  /* XXX: to be scope conscious */
  int
  in6_are_prefix_equal(struct in6_addr *p1, struct in6_addr *p2, int len)
  {
          int bytelen, bitlen;
  
          /* sanity check */
          if (len < 0 || len > 128) {
                  log(LOG_ERR, "in6_are_prefix_equal: invalid prefix length(%d)\n",
                      len);
                  return 0;
          }
  
          bytelen = len / NBBY;
          bitlen = len % NBBY;
  
          if (bcmp(&p1->s6_addr, &p2->s6_addr, bytelen))
                  return 0;
          if (bitlen != 0 &&
              p1->s6_addr[bytelen] >> (NBBY - bitlen) !=
              p2->s6_addr[bytelen] >> (NBBY - bitlen))
                  return 0;
  
          return 1;
  }
  
  void
  in6_prefixlen2mask(struct in6_addr *maskp, int len)
  {
          static const u_char maskarray[NBBY] = {0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};
          int bytelen, bitlen, i;
  
          /* sanity check */
          if (len < 0 || len > 128) {
                  log(LOG_ERR, "in6_prefixlen2mask: invalid prefix length(%d)\n",
                      len);
                  return;
          }
  
          bzero(maskp, sizeof(*maskp));
          bytelen = len / NBBY;
          bitlen = len % NBBY;
          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. if no address was
   * found, return the first valid address from designated IF.
   */
  struct in6_ifaddr *
  in6_ifawithifp(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.
           */
          IFADDR_FOREACH(ifa, ifp) {
                  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;
  
          IFADDR_FOREACH(ifa, ifp) {
                  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(struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          struct in6_ifaddr *ia;
  
          IFADDR_FOREACH(ifa, ifp) {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  ia = (struct in6_ifaddr *)ifa;
                  if (ia->ia6_flags & IN6_IFF_TENTATIVE) {
                          /*
                           * The TENTATIVE flag was likely set by hand
                           * beforehand, implicitly indicating the need for DAD.
                           * We may be able to skip the random delay in this
                           * case, but we impose delays just in case.
                           */
                          nd6_dad_start(ifa,
                              arc4random() % (MAX_RTR_SOLICITATION_DELAY * hz));
                  }
          }
  
          /*
           * special cases, like 6to4, are handled in in6_ifattach
           */
          in6_ifattach(ifp, NULL);
  }
  
  int
  in6if_do_dad(struct ifnet *ifp)
  {
          if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                  return 0;
  
          switch (ifp->if_type) {
          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(void)
  {
          unsigned long maxmtu = 0;
          struct ifnet *ifp;
  
          TAILQ_FOREACH(ifp, &ifnet, if_list) {
                  /* this function can be called during ifnet initialization */
                  if (!ifp->if_afdata[AF_INET6])
                          continue;
                  if ((ifp->if_flags & IFF_LOOPBACK) == 0 &&
                      IN6_LINKMTU(ifp) > maxmtu)
                          maxmtu = IN6_LINKMTU(ifp);
          }
          if (maxmtu)          /* update only when maxmtu is positive */
                  in6_maxmtu = maxmtu;
  }
  
  /*
   * Provide the length of interface identifiers to be used for the link attached
   * to the given interface.  The length should be defined in "IPv6 over
   * xxx-link" document.  Note that address architecture might also define
   * the length for a particular set of address prefixes, regardless of the
   * link type.  As clarified in rfc2462bis, those two definitions should be
   * consistent, and those really are as of August 2004.
   */
  int
  in6_if2idlen(struct ifnet *ifp)
  {
          switch (ifp->if_type) {
          case IFT_ETHER:         /* RFC2464 */
          case IFT_PROPVIRTUAL:   /* XXX: no RFC. treat it as ether */
          case IFT_L2VLAN:        /* ditto */
          case IFT_IEEE80211:     /* ditto */
          case IFT_FDDI:          /* RFC2467 */
          case IFT_ISO88025:      /* RFC2470 (IPv6 over Token Ring) */
          case IFT_PPP:           /* RFC2472 */
          case IFT_ARCNET:        /* RFC2497 */
          case IFT_FRELAY:        /* RFC2590 */
          case IFT_IEEE1394:      /* RFC3146 */
          case IFT_GIF:           /* draft-ietf-v6ops-mech-v2-07 */
          case IFT_LOOP:          /* XXX: is this really correct? */
                  return 64;
          default:
                  /*
                   * Unknown link type:
                   * It might be controversial to use the today's common constant
                   * of 64 for these cases unconditionally.  For full compliance,
                   * we should return an error in this case.  On the other hand,
                   * if we simply miss the standard for the link type or a new
                   * standard is defined for a new link type, the IFID length
                   * is very likely to be the common constant.  As a compromise,
                   * we always use the constant, but make an explicit notice
                   * indicating the "unknown" case.
                   */
                  printf("in6_if2idlen: unknown link type (%d)\n", ifp->if_type);
                  return 64;
          }
  }
  
  void *
  in6_domifattach(struct ifnet *ifp)
  {
          struct in6_ifextra *ext;
  
          ext = (struct in6_ifextra *)malloc(sizeof(*ext), M_IFADDR, M_WAITOK);
          bzero(ext, sizeof(*ext));
  
          ext->in6_ifstat = (struct in6_ifstat *)malloc(sizeof(struct in6_ifstat),
              M_IFADDR, M_WAITOK);
          bzero(ext->in6_ifstat, sizeof(*ext->in6_ifstat));
  
          ext->icmp6_ifstat =
              (struct icmp6_ifstat *)malloc(sizeof(struct icmp6_ifstat),
              M_IFADDR, M_WAITOK);
          bzero(ext->icmp6_ifstat, sizeof(*ext->icmp6_ifstat));
  
          ext->nd_ifinfo = nd6_ifattach(ifp);
          ext->scope6_id = scope6_ifattach(ifp);
          return ext;
  }
  
  void
  in6_domifdetach(struct ifnet *ifp, void *aux)
  {
          struct in6_ifextra *ext = (struct in6_ifextra *)aux;
  
          nd6_ifdetach(ext->nd_ifinfo);
          free(ext->in6_ifstat, M_IFADDR);
          free(ext->icmp6_ifstat, M_IFADDR);
          scope6_ifdetach(ext->scope6_id);
          free(ext, M_IFADDR);
  }
  
  /*
   * 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;
  
          sin6_p = malloc(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;
  }

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