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

     /*-
      * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the project nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      $KAME: in6.c,v 1.259 2002/01/21 11:37:50 keiichi Exp $
     */
    
    /*-
     * 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.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)in.c        8.2 (Berkeley) 11/15/93
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.2/sys/netinet6/in6.c 285822 2015-07-23 19:54:42Z hrs $");
    
    #include "opt_compat.h"
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/errno.h>
    #include <sys/jail.h>
    #include <sys/malloc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sockio.h>
    #include <sys/systm.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/time.h>
    #include <sys/kernel.h>
    #include <sys/syslog.h>
    
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_types.h>
    #include <net/route.h>
    #include <net/if_dl.h>
    #include <net/vnet.h>
    
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <net/if_llatbl.h>
    #include <netinet/if_ether.h>
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/in_pcb.h>
    #include <netinet/ip_carp.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 <netinet6/in6_pcb.h>
   
   VNET_DECLARE(int, icmp6_nodeinfo_oldmcprefix);
   #define V_icmp6_nodeinfo_oldmcprefix    VNET(icmp6_nodeinfo_oldmcprefix)
   
   /*
    * Definitions of some costant IP6 addresses.
    */
   const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
   const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
   const struct in6_addr in6addr_nodelocal_allnodes =
           IN6ADDR_NODELOCAL_ALLNODES_INIT;
   const struct in6_addr in6addr_linklocal_allnodes =
           IN6ADDR_LINKLOCAL_ALLNODES_INIT;
   const struct in6_addr in6addr_linklocal_allrouters =
           IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
   const struct in6_addr in6addr_linklocal_allv2routers =
           IN6ADDR_LINKLOCAL_ALLV2ROUTERS_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, caddr_t,
           struct ifnet *, struct thread *);
   static int in6_ifinit(struct ifnet *, struct in6_ifaddr *,
           struct sockaddr_in6 *, int);
   static void in6_unlink_ifa(struct in6_ifaddr *, struct ifnet *);
   
   int     (*faithprefix_p)(struct in6_addr *);
   
   #define ifa2ia6(ifa)    ((struct in6_ifaddr *)(ifa))
   #define ia62ifa(ia6)    (&((ia6)->ia_ifa))
   
   void
   in6_ifaddloop(struct ifaddr *ifa)
   {
           struct sockaddr_dl gateway;
           struct sockaddr_in6 mask, addr;
           struct rtentry rt;
           struct in6_ifaddr *ia;
           struct ifnet *ifp;
           struct llentry *ln;
   
           ia = ifa2ia6(ifa);
           ifp = ifa->ifa_ifp;
           /*
            * initialize for rtmsg generation
            */
           bzero(&gateway, sizeof(gateway));
           gateway.sdl_len = sizeof(gateway);
           gateway.sdl_family = AF_LINK;
           if (nd6_need_cache(ifp) != 0) {
                   IF_AFDATA_LOCK(ifp);
                   ifa->ifa_rtrequest = nd6_rtrequest;
                   ln = lla_lookup(LLTABLE6(ifp), (LLE_CREATE | LLE_IFADDR |
                       LLE_EXCLUSIVE), (struct sockaddr *)&ia->ia_addr);
                   IF_AFDATA_UNLOCK(ifp);
                   if (ln != NULL) {
                           ln->la_expire = 0;  /* for IPv6 this means permanent */
                           ln->ln_state = ND6_LLINFO_REACHABLE;
   
                           gateway.sdl_alen = 6;
                           memcpy(gateway.sdl_data, &ln->ll_addr.mac_aligned,
                               sizeof(ln->ll_addr));
                           LLE_WUNLOCK(ln);
                   }
           }
           bzero(&rt, sizeof(rt));
           rt.rt_gateway = (struct sockaddr *)&gateway;
           memcpy(&mask, &ia->ia_prefixmask, sizeof(ia->ia_prefixmask));
           memcpy(&addr, &ia->ia_addr, sizeof(ia->ia_addr));
           rt_mask(&rt) = (struct sockaddr *)&mask;
           rt_key(&rt) = (struct sockaddr *)&addr;
           rt.rt_flags = RTF_UP | RTF_HOST | RTF_STATIC;
           /* Announce arrival of local address to all FIBs. */
           rt_newaddrmsg(RTM_ADD, ifa, 0, &rt);
   }
   
   void
   in6_ifremloop(struct ifaddr *ifa)
   {
           struct sockaddr_dl gateway;
           struct sockaddr_in6 mask, addr;
           struct rtentry rt0;
           struct in6_ifaddr *ia;
           struct ifnet *ifp;
   
           ia = ifa2ia6(ifa);
           ifp = ifa->ifa_ifp;
           memcpy(&addr, &ia->ia_addr, sizeof(ia->ia_addr));
           memcpy(&mask, &ia->ia_prefixmask, sizeof(ia->ia_prefixmask));
           lltable_prefix_free(AF_INET6, (struct sockaddr *)&addr,
                       (struct sockaddr *)&mask, LLE_STATIC);
   
           /*
            * initialize for rtmsg generation
            */
           bzero(&gateway, sizeof(gateway));
           gateway.sdl_len = sizeof(gateway);
           gateway.sdl_family = AF_LINK;
           gateway.sdl_nlen = 0;
           gateway.sdl_alen = ifp->if_addrlen;
           bzero(&rt0, sizeof(rt0));
           rt0.rt_gateway = (struct sockaddr *)&gateway;
           rt_mask(&rt0) = (struct sockaddr *)&mask;
           rt_key(&rt0) = (struct sockaddr *)&addr;
           rt0.rt_flags = RTF_HOST | RTF_STATIC;
           /* Announce removal of local address to all FIBs. */
           rt_newaddrmsg(RTM_DELETE, ifa, 0, &rt0);
   }
   
   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 < 8; y++) {
                           if ((*p & (0x80 >> y)) == 0)
                                   break;
                   }
           }
   
           /*
            * when the limit pointer is given, do a stricter check on the
            * remaining bits.
            */
           if (p < lim) {
                   if (y != 0 && (*p & (0x00ff >> y)) != 0)
                           return (-1);
                   for (p = p + 1; p < lim; p++)
                           if (*p != 0)
                                   return (-1);
           }
   
           return x * 8 + y;
   }
   
   #ifdef COMPAT_FREEBSD32
   struct in6_ndifreq32 {
           char ifname[IFNAMSIZ];
           uint32_t ifindex;
   };
   #define SIOCGDEFIFACE32_IN6     _IOWR('i', 86, struct in6_ndifreq32)
   #endif
   
   int
   in6_control(struct socket *so, u_long cmd, caddr_t data,
       struct ifnet *ifp, struct thread *td)
   {
           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 carp_attached = 0;
           int error;
           u_long ocmd = cmd;
   
           /*
            * Compat to make pre-10.x ifconfig(8) operable.
            */
           if (cmd == OSIOCAIFADDR_IN6)
                   cmd = SIOCAIFADDR_IN6;
   
           switch (cmd) {
           case SIOCGETSGCNT_IN6:
           case SIOCGETMIFCNT_IN6:
                   /*
                    * XXX mrt_ioctl has a 3rd, unused, FIB argument in route.c.
                    * We cannot see how that would be needed, so do not adjust the
                    * KPI blindly; more likely should clean up the IPv4 variant.
                    */
                   return (mrt6_ioctl ? mrt6_ioctl(cmd, data) : EOPNOTSUPP);
           }
   
           switch (cmd) {
           case SIOCAADDRCTL_POLICY:
           case SIOCDADDRCTL_POLICY:
                   if (td != NULL) {
                           error = priv_check(td, PRIV_NETINET_ADDRCTRL6);
                           if (error)
                                   return (error);
                   }
                   return (in6_src_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 (td != NULL) {
                           error = priv_check(td, PRIV_NETINET_ND6);
                           if (error)
                                   return (error);
                   }
                   /* 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));
   
   #ifdef COMPAT_FREEBSD32
           case SIOCGDEFIFACE32_IN6:
                   {
                           struct in6_ndifreq ndif;
                           struct in6_ndifreq32 *ndif32;
   
                           error = nd6_ioctl(SIOCGDEFIFACE_IN6, (caddr_t)&ndif,
                               ifp);
                           if (error)
                                   return (error);
                           ndif32 = (struct in6_ndifreq32 *)data;
                           ndif32->ifindex = ndif.ifindex;
                           return (0);
                   }
   #endif
           }
   
           switch (cmd) {
           case SIOCSIFPREFIX_IN6:
           case SIOCDIFPREFIX_IN6:
           case SIOCAIFPREFIX_IN6:
           case SIOCCIFPREFIX_IN6:
           case SIOCSGIFPREFIX_IN6:
           case SIOCGIFPREFIX_IN6:
                   log(LOG_NOTICE,
                       "prefix ioctls are now invalidated. "
                       "please use ifconfig.\n");
                   return (EOPNOTSUPP);
           }
   
           switch (cmd) {
           case SIOCSSCOPE6:
                   if (td != NULL) {
                           error = priv_check(td, PRIV_NETINET_SCOPE6);
                           if (error)
                                   return (error);
                   }
                   /* FALLTHROUGH */
           case SIOCGSCOPE6:
           case SIOCGSCOPE6DEF:
                   return (scope6_ioctl(cmd, data, ifp));
           }
   
           switch (cmd) {
           case SIOCALIFADDR:
                   if (td != NULL) {
                           error = priv_check(td, PRIV_NET_ADDIFADDR);
                           if (error)
                                   return (error);
                   }
                   return in6_lifaddr_ioctl(so, cmd, data, ifp, td);
   
           case SIOCDLIFADDR:
                   if (td != NULL) {
                           error = priv_check(td, PRIV_NET_DELIFADDR);
                           if (error)
                                   return (error);
                   }
                   /* FALLTHROUGH */
           case SIOCGLIFADDR:
                   return in6_lifaddr_ioctl(so, cmd, data, ifp, td);
           }
   
           /*
            * 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 SIOCSIFALIFETIME_IN6:
           case SIOCGIFSTAT_IN6:
           case SIOCGIFSTAT_ICMP6:
                   sa6 = &ifr->ifr_addr;
                   break;
           case SIOCSIFADDR:
           case SIOCSIFBRDADDR:
           case SIOCSIFDSTADDR:
           case SIOCSIFNETMASK:
                   /*
                    * Although we should pass any non-INET6 ioctl requests
                    * down to driver, we filter some legacy INET requests.
                    * Drivers trust SIOCSIFADDR et al to come from an already
                    * privileged layer, and do not perform any credentials
                    * checks or input validation.
                    */
                   return (EINVAL);
           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);
                   if (td != NULL && (error = prison_check_ip6(td->td_ucred,
                       &sa6->sin6_addr)) != 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.
                    */
                   /* we decided to obsolete this command (20000704) */
                   error = EINVAL;
                   goto out;
   
           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) {
                           error = EADDRNOTAVAIL;
                           goto out;
                   }
                   /* 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)) {
                           error = EAFNOSUPPORT;
                           goto out;
                   }
   
                   if (td != NULL) {
                           error = priv_check(td, (cmd == SIOCDIFADDR_IN6) ?
                               PRIV_NET_DELIFADDR : PRIV_NET_ADDIFADDR);
                           if (error)
                                   goto out;
                   }
                   /* FALLTHROUGH */
           case SIOCGIFSTAT_IN6:
           case SIOCGIFSTAT_ICMP6:
                   if (ifp->if_afdata[AF_INET6] == NULL) {
                           error = EPFNOSUPPORT;
                           goto out;
                   }
                   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) {
                           error = EADDRNOTAVAIL;
                           goto out;
                   }
                   break;
   
           case SIOCSIFALIFETIME_IN6:
               {
                   struct in6_addrlifetime *lt;
   
                   if (td != NULL) {
                           error = priv_check(td, PRIV_NETINET_ALIFETIME6);
                           if (error)
                                   goto out;
                   }
                   if (ia == NULL) {
                           error = EADDRNOTAVAIL;
                           goto out;
                   }
                   /* sanity for overflow - beware unsigned */
                   lt = &ifr->ifr_ifru.ifru_lifetime;
                   if (lt->ia6t_vltime != ND6_INFINITE_LIFETIME &&
                       lt->ia6t_vltime + time_uptime < time_uptime) {
                           error = EINVAL;
                           goto out;
                   }
                   if (lt->ia6t_pltime != ND6_INFINITE_LIFETIME &&
                       lt->ia6t_pltime + time_uptime < time_uptime) {
                           error = EINVAL;
                           goto out;
                   }
                   break;
               }
           }
   
           switch (cmd) {
           case SIOCGIFADDR_IN6:
                   ifr->ifr_addr = ia->ia_addr;
                   if ((error = sa6_recoverscope(&ifr->ifr_addr)) != 0)
                           goto out;
                   break;
   
           case SIOCGIFDSTADDR_IN6:
                   if ((ifp->if_flags & IFF_POINTOPOINT) == 0) {
                           error = EINVAL;
                           goto out;
                   }
                   /*
                    * 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)
                           goto out;
                   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:
                   COUNTER_ARRAY_COPY(((struct in6_ifextra *)
                       ifp->if_afdata[AF_INET6])->in6_ifstat,
                       &ifr->ifr_ifru.ifru_stat,
                       sizeof(struct in6_ifstat) / sizeof(uint64_t));
                   break;
   
           case SIOCGIFSTAT_ICMP6:
                   COUNTER_ARRAY_COPY(((struct in6_ifextra *)
                       ifp->if_afdata[AF_INET6])->icmp6_ifstat,
                       &ifr->ifr_ifru.ifru_icmp6stat,
                       sizeof(struct icmp6_ifstat) / sizeof(uint64_t));
                   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 = (-1) &
                               ~((time_t)1 << ((sizeof(maxexpire) * 8) - 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 = (-1) &
                               ~((time_t)1 << ((sizeof(maxexpire) * 8) - 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 SIOCSIFALIFETIME_IN6:
                   ia->ia6_lifetime = ifr->ifr_ifru.ifru_lifetime;
                   /* for sanity */
                   if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                           ia->ia6_lifetime.ia6t_expire =
                                   time_uptime + 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_uptime + ia->ia6_lifetime.ia6t_pltime;
                   } else
                           ia->ia6_lifetime.ia6t_preferred = 0;
                   break;
   
           case SIOCAIFADDR_IN6:
           {
                   int i;
                   struct nd_prefixctl pr0;
                   struct nd_prefix *pr;
   
                   /*
                    * first, make or update the interface address structure,
                    * and link it to the list.
                    */
                   if ((error = in6_update_ifa(ifp, ifra, ia, 0)) != 0)
                           goto out;
                   if (ia != NULL)
                           ifa_free(&ia->ia_ifa);
                   if ((ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr))
                       == NULL) {
                           /*
                            * this can happen when the user specify the 0 valid
                            * lifetime.
                            */
                           break;
                   }
   
                   if (cmd == ocmd && ifra->ifra_vhid > 0) {
                           if (carp_attach_p != NULL)
                                   error = (*carp_attach_p)(&ia->ia_ifa,
                                       ifra->ifra_vhid);
                           else
                                   error = EPROTONOSUPPORT;
                           if (error)
                                   goto out;
                           else
                                   carp_attached = 1;
                   }
   
                   /*
                    * 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) {
                           /* we don't need to install a host route. */
                           goto aifaddr_out;
                   }
                   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) {
                                   if (carp_attached)
                                           (*carp_detach_p)(&ia->ia_ifa);
                                   goto out;
                           }
                           if (pr == NULL) {
                                   if (carp_attached)
                                           (*carp_detach_p)(&ia->ia_ifa);
                                   log(LOG_ERR, "nd6_prelist_add succeeded but "
                                       "no prefix\n");
                                   error = EINVAL;
                                   goto out;
                           }
                   }
   
                   /* 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) &&
                               V_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();
   aifaddr_out:
                   if (error != 0 || ia == NULL)
                           break;
                   /*
                    * Try to clear the flag when a new IPv6 address is added
                    * onto an IFDISABLED interface and it succeeds.
                    */
                   if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) {
                           struct in6_ndireq nd;
   
                           memset(&nd, 0, sizeof(nd));
                           nd.ndi.flags = ND_IFINFO(ifp)->flags;
                           nd.ndi.flags &= ~ND6_IFF_IFDISABLED;
                           if (nd6_ioctl(SIOCSIFINFO_FLAGS, (caddr_t)&nd, ifp) < 0)
                                   log(LOG_NOTICE, "SIOCAIFADDR_IN6: "
                                       "SIOCSIFINFO_FLAGS for -ifdisabled "
                                       "failed.");
                           /*
                            * Ignore failure of clearing the flag intentionally.
                            * The failure means address duplication was detected.
                            */
                   }
                   EVENTHANDLER_INVOKE(ifaddr_event, ifp);
                   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);
                   EVENTHANDLER_INVOKE(ifaddr_event, ifp);
                   break;
           }
   
           default:
                   if (ifp->if_ioctl == NULL) {
                           error = EOPNOTSUPP;
                           goto out;
                   }
                   error = (*ifp->if_ioctl)(ifp, cmd, data);
                   goto out;
           }
   
           error = 0;
   out:
           if (ia != NULL)
                   ifa_free(&ia->ia_ifa);
           return (error);
   }
   
   
   /*
    * Join necessary multicast groups.  Factored out from in6_update_ifa().
    * This entire work should only be done once, for the default FIB.
    */
   static int
   in6_update_ifa_join_mc(struct ifnet *ifp, struct in6_aliasreq *ifra,
       struct in6_ifaddr *ia, int flags, struct in6_multi **in6m_sol)
   {
           char ip6buf[INET6_ADDRSTRLEN];
           struct sockaddr_in6 mltaddr, mltmask;
           struct in6_addr llsol;
           struct in6_multi_mship *imm;
           struct rtentry *rt;
           int delay, error;
   
           KASSERT(in6m_sol != NULL, ("%s: in6m_sol is NULL", __func__));
   
           /* Join solicited multicast addr for new host id. */
           bzero(&llsol, sizeof(struct in6_addr));
           llsol.s6_addr32[0] = IPV6_ADDR_INT32_MLL;
           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, "%s: in6_setscope failed\n", __func__);
                   goto cleanup;
           }
           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.
                    * [RFC 4861, Section 6.3.7]
                    */
                   delay = arc4random() % (MAX_RTR_SOLICITATION_DELAY * hz);
           }
           imm = in6_joingroup(ifp, &llsol, &error, delay);
           if (imm == NULL) {
                   nd6log((LOG_WARNING, "%s: addmulti failed for %s on %s "
                       "(errno=%d)\n", __func__, ip6_sprintf(ip6buf, &llsol),
                       if_name(ifp), error));
                   goto cleanup;
           }
           LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
           *in6m_sol = imm->i6mm_maddr;
   
           bzero(&mltmask, sizeof(mltmask));
           mltmask.sin6_len = sizeof(struct sockaddr_in6);
           mltmask.sin6_family = AF_INET6;
           mltmask.sin6_addr = in6mask32;
   #define MLTMASK_LEN  4  /* mltmask's masklen (=32bit=4octet) */
   
           /*
            * Join link-local all-nodes address.
            */
           bzero(&mltaddr, sizeof(mltaddr));
           mltaddr.sin6_len = sizeof(struct sockaddr_in6);
           mltaddr.sin6_family = AF_INET6;
           mltaddr.sin6_addr = in6addr_linklocal_allnodes;
           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 = in6_rtalloc1((struct sockaddr *)&mltaddr, 0, 0UL, RT_DEFAULT_FIB);
           if (rt != NULL) {
                   /* XXX: only works in !SCOPEDROUTING case. */
                   if (memcmp(&mltaddr.sin6_addr,
                       &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr,
                       MLTMASK_LEN)) {
                           RTFREE_LOCKED(rt);
                           rt = NULL;
                   }
           }
           if (rt == NULL) {
                   error = in6_rtrequest(RTM_ADD, (struct sockaddr *)&mltaddr,
                       (struct sockaddr *)&ia->ia_addr,
                       (struct sockaddr *)&mltmask, RTF_UP,
                       (struct rtentry **)0, RT_DEFAULT_FIB);
                   if (error)
                           goto cleanup;
           } else
                   RTFREE_LOCKED(rt);
   
           imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
           if (imm == NULL) {
                   nd6log((LOG_WARNING, "%s: addmulti failed for %s on %s "
                       "(errno=%d)\n", __func__, ip6_sprintf(ip6buf,
                       &mltaddr.sin6_addr), if_name(ifp), error));
                   goto cleanup;
           }
           LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
   
           /*
            * Join node information group address.
            */
           delay = 0;
           if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                   /*
                    * The spec does not say anything about delay for this group,
                    * but the same logic should apply.
                    */
                   delay = arc4random() % (MAX_RTR_SOLICITATION_DELAY * hz);
           }
           if (in6_nigroup(ifp, NULL, -1, &mltaddr.sin6_addr) == 0) {
                   /* XXX jinmei */
                   imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, delay);
                   if (imm == NULL)
                           nd6log((LOG_WARNING, "%s: addmulti failed for %s on %s "
                               "(errno=%d)\n", __func__, ip6_sprintf(ip6buf,
                               &mltaddr.sin6_addr), if_name(ifp), error));
                           /* XXX not very fatal, go on... */
                   else
                           LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
           }
           if (V_icmp6_nodeinfo_oldmcprefix && 
                in6_nigroup_oldmcprefix(ifp, NULL, -1, &mltaddr.sin6_addr) == 0) {
                   imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, delay);
                   if (imm == NULL)
                           nd6log((LOG_WARNING, "%s: addmulti failed for %s on %s "
                               "(errno=%d)\n", __func__, ip6_sprintf(ip6buf,
                               &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 = in6_rtalloc1((struct sockaddr *)&mltaddr, 0, 0UL, RT_DEFAULT_FIB);
           if (rt != NULL) {
                   if (memcmp(&mltaddr.sin6_addr,
                       &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr,
                       MLTMASK_LEN)) {
                           RTFREE_LOCKED(rt);
                           rt = NULL;
                   }
           }
           if (rt == NULL) {
                   error = in6_rtrequest(RTM_ADD, (struct sockaddr *)&mltaddr,
                       (struct sockaddr *)&ia->ia_addr,
                       (struct sockaddr *)&mltmask, RTF_UP,
                       (struct rtentry **)0, RT_DEFAULT_FIB);
                   if (error)
                           goto cleanup;
           } else
                   RTFREE_LOCKED(rt);
   
           imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
           if (imm == NULL) {
                  nd6log((LOG_WARNING, "%s: addmulti failed for %s on %s "
                      "(errno=%d)\n", __func__, ip6_sprintf(ip6buf,
                      &mltaddr.sin6_addr), if_name(ifp), error));
                  goto cleanup;
          }
          LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
  #undef  MLTMASK_LEN
  
  cleanup:
          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().
   */
  int
  in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
      struct in6_ifaddr *ia, int flags)
  {
          int error = 0, hostIsNew = 0, plen = -1;
          struct sockaddr_in6 dst6;
          struct in6_addrlifetime *lt;
          struct in6_multi *in6m_sol;
          int delay;
          char ip6buf[INET6_ADDRSTRLEN];
  
          /* 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) {
                  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"));
                          return (EINVAL);
                  }
          }
          /* 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(ip6buf, &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((caddr_t)ia, sizeof(*ia));
                  ifa_init(&ia->ia_ifa);
                  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_uptime;
                  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;
                  ifa_ref(&ia->ia_ifa);                   /* if_addrhead */
                  IF_ADDR_WLOCK(ifp);
                  TAILQ_INSERT_TAIL(&ifp->if_addrhead, &ia->ia_ifa, ifa_link);
                  IF_ADDR_WUNLOCK(ifp);
  
                  ifa_ref(&ia->ia_ifa);                   /* in6_ifaddrhead */
                  IN6_IFADDR_WLOCK();
                  TAILQ_INSERT_TAIL(&V_in6_ifaddrhead, ia, ia_link);
                  LIST_INSERT_HEAD(IN6ADDR_HASH(&ifra->ifra_addr.sin6_addr),
                      ia, ia6_hash);
                  IN6_IFADDR_WUNLOCK();
          }
  
          /* update timestamp */
          ia->ia6_updatetime = time_uptime;
  
          /* 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(ip6buf, &ia->ia_addr.sin6_addr)));
                          error = EINVAL;
                          goto unlink;
                  }
                  ia->ia_prefixmask = ifra->ifra_prefixmask;
                  ia->ia_prefixmask.sin6_family = AF_INET6;
          }
  
          /*
           * If a new destination address is specified, scrub the old one and
           * install the new destination.  Note that the interface must be
           * p2p or loopback (see the check above.)
           */
          if (dst6.sin6_family == AF_INET6 &&
              !IN6_ARE_ADDR_EQUAL(&dst6.sin6_addr, &ia->ia_dstaddr.sin6_addr)) {
                  int e;
  
                  if ((ia->ia_flags & IFA_ROUTE) != 0 &&
                      (e = rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST)) != 0) {
                          nd6log((LOG_ERR, "in6_update_ifa: failed to remove "
                              "a route to the old destination: %s\n",
                              ip6_sprintf(ip6buf, &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_uptime + 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_uptime + 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_uptime;
          }
          /*
           * 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;
  
          /* DAD should be performed after ND6_IFF_IFDISABLED is cleared. */
          if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)
                  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. */
          in6m_sol = NULL;
          if ((ifp->if_flags & IFF_MULTICAST) != 0) {
                  error = in6_update_ifa_join_mc(ifp, ifra, ia, flags, &in6m_sol);
                  if (error)
                          goto cleanup;
          }
  
          /*
           * Perform DAD, if needed.
           * XXX It may be of use, if we can administratively disable DAD.
           */
          if (in6if_do_dad(ifp) && ((ifra->ifra_flags & IN6_IFF_NODAD) == 0) &&
              (ia->ia6_flags & IN6_IFF_TENTATIVE))
          {
                  int mindelay, maxdelay;
  
                  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).
                           * XXX: Break data hiding guidelines and look at
                           * state for the solicited multicast group.
                           */
                          mindelay = 0;
                          if (in6m_sol != NULL &&
                              in6m_sol->in6m_state == MLD_REPORTING_MEMBER) {
                                  mindelay = in6m_sol->in6m_timer;
                          }
                          maxdelay = MAX_RTR_SOLICITATION_DELAY * hz;
                          if (maxdelay - mindelay == 0)
                                  delay = 0;
                          else {
                                  delay =
                                      (arc4random() % (maxdelay - mindelay)) +
                                      mindelay;
                          }
                  }
                  nd6_dad_start((struct ifaddr *)ia, delay);
          }
  
          KASSERT(hostIsNew, ("in6_update_ifa: !hostIsNew"));
          ifa_free(&ia->ia_ifa);
          return (error);
  
    unlink:
          /*
           * XXX: if a change of an existing address failed, keep the entry
           * anyway.
           */
          if (hostIsNew) {
                  in6_unlink_ifa(ia, ifp);
                  ifa_free(&ia->ia_ifa);
          }
          return (error);
  
    cleanup:
          KASSERT(hostIsNew, ("in6_update_ifa: cleanup: !hostIsNew"));
          ifa_free(&ia->ia_ifa);
          in6_purgeaddr(&ia->ia_ifa);
          return error;
  }
  
  /*
   * Leave multicast groups.  Factored out from in6_purgeaddr().
   * This entire work should only be done once, for the default FIB.
   */
  static int
  in6_purgeaddr_mc(struct ifnet *ifp, struct in6_ifaddr *ia, struct ifaddr *ifa0)
  {
          struct sockaddr_in6 mltaddr, mltmask;
          struct in6_multi_mship *imm;
          struct rtentry *rt;
          struct sockaddr_in6 sin6;
          int error;
  
          /*
           * 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);
          }
  
          /*
           * Remove the link-local all-nodes address.
           */
          bzero(&mltmask, sizeof(mltmask));
          mltmask.sin6_len = sizeof(struct sockaddr_in6);
          mltmask.sin6_family = AF_INET6;
          mltmask.sin6_addr = in6mask32;
  
          bzero(&mltaddr, sizeof(mltaddr));
          mltaddr.sin6_len = sizeof(struct sockaddr_in6);
          mltaddr.sin6_family = AF_INET6;
          mltaddr.sin6_addr = in6addr_linklocal_allnodes;
  
          if ((error = in6_setscope(&mltaddr.sin6_addr, ifp, NULL)) != 0)
                  return (error);
  
          /*
           * As for the mltaddr above, proactively prepare the sin6 to avoid
           * rtentry un- and re-locking.
           */
          if (ifa0 != NULL) {
                  bzero(&sin6, sizeof(sin6));
                  sin6.sin6_len = sizeof(sin6);
                  sin6.sin6_family = AF_INET6;
                  memcpy(&sin6.sin6_addr, &satosin6(ifa0->ifa_addr)->sin6_addr,
                      sizeof(sin6.sin6_addr));
                  error = in6_setscope(&sin6.sin6_addr, ifa0->ifa_ifp, NULL);
                  if (error != 0)
                          return (error);
          }
  
          rt = in6_rtalloc1((struct sockaddr *)&mltaddr, 0, 0UL, RT_DEFAULT_FIB);
          if (rt != NULL && rt->rt_gateway != NULL &&
              (memcmp(&satosin6(rt->rt_gateway)->sin6_addr,
                      &ia->ia_addr.sin6_addr,
                      sizeof(ia->ia_addr.sin6_addr)) == 0)) {
                  /*
                   * If no more IPv6 address exists on this interface then
                   * remove the multicast address route.
                   */
                  if (ifa0 == NULL) {
                          memcpy(&mltaddr.sin6_addr,
                              &satosin6(rt_key(rt))->sin6_addr,
                              sizeof(mltaddr.sin6_addr));
                          RTFREE_LOCKED(rt);
                          error = in6_rtrequest(RTM_DELETE,
                              (struct sockaddr *)&mltaddr,
                              (struct sockaddr *)&ia->ia_addr,
                              (struct sockaddr *)&mltmask, RTF_UP,
                              (struct rtentry **)0, RT_DEFAULT_FIB);
                          if (error)
                                  log(LOG_INFO, "%s: link-local all-nodes "
                                      "multicast address deletion error\n",
                                      __func__);
                  } else {
                          /*
                           * Replace the gateway of the route.
                           */
                          memcpy(rt->rt_gateway, &sin6, sizeof(sin6));
                          RTFREE_LOCKED(rt);
                  }
          } else {
                  if (rt != NULL)
                          RTFREE_LOCKED(rt);
          }
  
          /*
           * Remove the node-local all-nodes address.
           */
          mltaddr.sin6_addr = in6addr_nodelocal_allnodes;
          if ((error = in6_setscope(&mltaddr.sin6_addr, ifp, NULL)) != 0)
                  return (error);
  
          rt = in6_rtalloc1((struct sockaddr *)&mltaddr, 0, 0UL, RT_DEFAULT_FIB);
          if (rt != NULL && rt->rt_gateway != NULL &&
              (memcmp(&satosin6(rt->rt_gateway)->sin6_addr,
                      &ia->ia_addr.sin6_addr,
                      sizeof(ia->ia_addr.sin6_addr)) == 0)) {
                  /*
                   * If no more IPv6 address exists on this interface then
                   * remove the multicast address route.
                   */
                  if (ifa0 == NULL) {
                          memcpy(&mltaddr.sin6_addr,
                              &satosin6(rt_key(rt))->sin6_addr,
                              sizeof(mltaddr.sin6_addr));
  
                          RTFREE_LOCKED(rt);
                          error = in6_rtrequest(RTM_DELETE,
                              (struct sockaddr *)&mltaddr,
                              (struct sockaddr *)&ia->ia_addr,
                              (struct sockaddr *)&mltmask, RTF_UP,
                              (struct rtentry **)0, RT_DEFAULT_FIB);
                          if (error)
                                  log(LOG_INFO, "%s: node-local all-nodes"
                                      "multicast address deletion error\n",
                                      __func__);
                  } else {
                          /*
                           * Replace the gateway of the route.
                           */
                          memcpy(rt->rt_gateway, &sin6, sizeof(sin6));
                          RTFREE_LOCKED(rt);
                  }
          } else {
                  if (rt != NULL)
                          RTFREE_LOCKED(rt);
          }
  
          return (0);
  }
  
  void
  in6_purgeaddr(struct ifaddr *ifa)
  {
          struct ifnet *ifp = ifa->ifa_ifp;
          struct in6_ifaddr *ia = (struct in6_ifaddr *) ifa;
          int plen, error;
          struct ifaddr *ifa0;
  
          if (ifa->ifa_carp)
                  (*carp_detach_p)(ifa);
  
          /*
           * find another IPv6 address as the gateway for the
           * link-local and node-local all-nodes multicast
           * address routes
           */
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa0, &ifp->if_addrhead, ifa_link) {
                  if ((ifa0->ifa_addr->sa_family != AF_INET6) ||
                      memcmp(&satosin6(ifa0->ifa_addr)->sin6_addr,
                      &ia->ia_addr.sin6_addr, sizeof(struct in6_addr)) == 0)
                          continue;
                  else
                          break;
          }
          if (ifa0 != NULL)
                  ifa_ref(ifa0);
          IF_ADDR_RUNLOCK(ifp);
  
          /*
           * Remove the loopback route to the interface address.
           * The check for the current setting of "nd6_useloopback"
           * is not needed.
           */
          if (ia->ia_flags & IFA_RTSELF) {
                  error = ifa_del_loopback_route((struct ifaddr *)ia,
                      (struct sockaddr *)&ia->ia_addr);
                  if (error == 0)
                          ia->ia_flags &= ~IFA_RTSELF;
          }
  
          /* stop DAD processing */
          nd6_dad_stop(ifa);
  
          /* Remove local address entry from lltable. */
          in6_ifremloop(ifa);
  
          /* Leave multicast groups. */
          error = in6_purgeaddr_mc(ifp, ia, ifa0);
  
          if (ifa0 != NULL)
                  ifa_free(ifa0);
  
          plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL); /* XXX */
          if ((ia->ia_flags & IFA_ROUTE) && plen == 128) {
                  error = rtinit(&(ia->ia_ifa), RTM_DELETE, ia->ia_flags |
                      (ia->ia_dstaddr.sin6_family == AF_INET6) ? RTF_HOST : 0);
                  if (error != 0)
                          log(LOG_INFO, "%s: err=%d, destination address delete "
                              "failed\n", __func__, error);
                  ia->ia_flags &= ~IFA_ROUTE;
          }
  
          in6_unlink_ifa(ia, ifp);
  }
  
  static void
  in6_unlink_ifa(struct in6_ifaddr *ia, struct ifnet *ifp)
  {
          char ip6buf[INET6_ADDRSTRLEN];
  
          IF_ADDR_WLOCK(ifp);
          TAILQ_REMOVE(&ifp->if_addrhead, &ia->ia_ifa, ifa_link);
          IF_ADDR_WUNLOCK(ifp);
          ifa_free(&ia->ia_ifa);                  /* if_addrhead */
  
          /*
           * Defer the release of what might be the last reference to the
           * in6_ifaddr so that it can't be freed before the remainder of the
           * cleanup.
           */
          IN6_IFADDR_WLOCK();
          TAILQ_REMOVE(&V_in6_ifaddrhead, ia, ia_link);
          LIST_REMOVE(ia, ia6_hash);
          IN6_IFADDR_WUNLOCK();
  
          /*
           * Release the reference to the base prefix.  There should be a
           * positive reference.
           */
          if (ia->ia6_ndpr == NULL) {
                  nd6log((LOG_NOTICE,
                      "in6_unlink_ifa: autoconf'ed address "
                      "%s has no prefix\n", ip6_sprintf(ip6buf, IA6_IN6(ia))));
          } else {
                  ia->ia6_ndpr->ndpr_refcnt--;
                  ia->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 ((ia->ia6_flags & IN6_IFF_AUTOCONF)) {
                  pfxlist_onlink_check();
          }
          ifa_free(&ia->ia_ifa);                  /* in6_ifaddrhead */
  }
  
  void
  in6_purgeif(struct ifnet *ifp)
  {
          struct ifaddr *ifa, *nifa;
  
          TAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  in6_purgeaddr(ifa);
          }
  
          in6_ifdetach(ifp);
  }
  
  /*
   * SIOC[GAD]LIFADDR.
   *      SIOCGLIFADDR: get first address. (?)
   *      SIOCGLIFADDR with IFLR_PREFIX:
   *              get first address that matches the specified prefix.
   *      SIOCALIFADDR: add the specified address.
   *      SIOCALIFADDR with IFLR_PREFIX:
   *              add the specified prefix, filling hostid part from
   *              the first link-local address.  prefixlen must be <= 64.
   *      SIOCDLIFADDR: delete the specified address.
   *      SIOCDLIFADDR with IFLR_PREFIX:
   *              delete the first address that matches the specified prefix.
   * return values:
   *      EINVAL on invalid parameters
   *      EADDRNOTAVAIL on prefix match failed/specified address not found
   *      other values may be returned from in6_ioctl()
   *
   * NOTE: SIOCALIFADDR(with IFLR_PREFIX set) allows prefixlen less than 64.
   * this is to accomodate address naming scheme other than RFC2374,
   * in the future.
   * RFC2373 defines interface id to be 64bit, but it allows non-RFC2374
   * address encoding scheme. (see figure on page 8)
   */
  static int
  in6_lifaddr_ioctl(struct socket *so, u_long cmd, caddr_t data,
      struct ifnet *ifp, struct thread *td)
  {
          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) * 8 < iflr->prefixlen)
                  return EINVAL;
  
          switch (cmd) {
          case SIOCALIFADDR:
              {
                  struct in6_aliasreq ifra;
                  struct in6_addr *hostid = NULL;
                  int prefixlen;
  
                  ifa = NULL;
                  if ((iflr->flags & IFLR_PREFIX) != 0) {
                          struct sockaddr_in6 *sin6;
  
                          /*
                           * hostid is to fill in the hostid part of the
                           * address.  hostid points to the first link-local
                           * address attached to the interface.
                           */
                          ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0);
                          if (!ifa)
                                  return EADDRNOTAVAIL;
                          hostid = IFA_IN6(ifa);
  
                          /* prefixlen must be <= 64. */
                          if (64 < iflr->prefixlen) {
                                  if (ifa != NULL)
                                          ifa_free(ifa);
                                  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) {
                                  if (ifa != NULL)
                                          ifa_free(ifa);
                                  return EINVAL;
                          }
                  } else
                          prefixlen = iflr->prefixlen;
  
                  /* copy args to in6_aliasreq, perform ioctl(SIOCAIFADDR_IN6). */
                  bzero(&ifra, sizeof(ifra));
                  bcopy(iflr->iflr_name, ifra.ifra_name, sizeof(ifra.ifra_name));
  
                  bcopy(&iflr->addr, &ifra.ifra_addr,
                      ((struct sockaddr *)&iflr->addr)->sa_len);
                  if (hostid) {
                          /* fill in hostid part */
                          ifra.ifra_addr.sin6_addr.s6_addr32[2] =
                              hostid->s6_addr32[2];
                          ifra.ifra_addr.sin6_addr.s6_addr32[3] =
                              hostid->s6_addr32[3];
                  }
  
                  if (((struct sockaddr *)&iflr->dstaddr)->sa_family) { /* XXX */
                          bcopy(&iflr->dstaddr, &ifra.ifra_dstaddr,
                              ((struct sockaddr *)&iflr->dstaddr)->sa_len);
                          if (hostid) {
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[2] =
                                      hostid->s6_addr32[2];
                                  ifra.ifra_dstaddr.sin6_addr.s6_addr32[3] =
                                      hostid->s6_addr32[3];
                          }
                  }
                  if (ifa != NULL)
                          ifa_free(ifa);
  
                  ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
                  in6_prefixlen2mask(&ifra.ifra_prefixmask.sin6_addr, prefixlen);
  
                  ifra.ifra_flags = iflr->flags & ~IFLR_PREFIX;
                  return in6_control(so, SIOCAIFADDR_IN6, (caddr_t)&ifra, ifp, td);
              }
          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;
                          }
                  }
  
                  IF_ADDR_RLOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          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 != NULL)
                          ifa_ref(ifa);
                  IF_ADDR_RUNLOCK(ifp);
                  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) {
                                  ifa_free(ifa);
                                  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) {
                                          ifa_free(ifa);
                                          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 */
                          ifa_free(ifa);
  
                          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;
                          ifa_free(ifa);
                          return in6_control(so, SIOCDIFADDR_IN6, (caddr_t)&ifra,
                              ifp, td);
                  }
              }
          }
  
          return EOPNOTSUPP;      /* just for safety */
  }
  
  /*
   * Initialize an interface's IPv6 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;
          struct ifaddr *ifa;
  
          /*
           * Give the interface a chance to initialize
           * if this is its first address,
           * and to validate the address if necessary.
           */
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  ifacount++;
          }
          IF_ADDR_RUNLOCK(ifp);
  
          ia->ia_addr = *sin6;
  
          if (ifacount <= 1 && ifp->if_ioctl) {
                  error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia);
                  if (error)
                          return (error);
          }
  
          ia->ia_ifa.ifa_metric = ifp->if_metric;
  
          /* we could do in(6)_socktrim here, but just omit it at this moment. */
  
          /*
           * Special case:
           * If a new destination address is specified for a point-to-point
           * interface, install a route to the destination as an interface
           * direct route.
           * XXX: the logic below rejects assigning multiple addresses on a p2p
           * interface that share the same destination.
           */
          plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL); /* XXX */
          if (!(ia->ia_flags & IFA_ROUTE) && plen == 128 &&
              ia->ia_dstaddr.sin6_family == AF_INET6) {
                  int rtflags = RTF_UP | RTF_HOST;
                  error = rtinit(&ia->ia_ifa, RTM_ADD, ia->ia_flags | rtflags);
                  if (error)
                          return (error);
                  ia->ia_flags |= IFA_ROUTE;
                  /*
                   * Handle the case for ::1 .
                   */
                  if (ifp->if_flags & IFF_LOOPBACK)
                          ia->ia_flags |= IFA_RTSELF;
          }
  
          /*
           * add a loopback route to self
           */
          if (!(ia->ia_flags & IFA_RTSELF) && V_nd6_useloopback) {
                  error = ifa_add_loopback_route((struct ifaddr *)ia,
                      (struct sockaddr *)&ia->ia_addr);
                  if (error == 0)
                          ia->ia_flags |= IFA_RTSELF;
          }
  
          /* Add local address to lltable, if necessary (ex. on p2p link). */
          if (newhost)
                  in6_ifaddloop(&(ia->ia_ifa));
  
          return (error);
  }
  
  /*
   * Find an IPv6 interface link-local address specific to an interface.
   * ifaddr is returned referenced.
   */
  struct in6_ifaddr *
  in6ifa_ifpforlinklocal(struct ifnet *ifp, int ignoreflags)
  {
          struct ifaddr *ifa;
  
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  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;
                          ifa_ref(ifa);
                          break;
                  }
          }
          IF_ADDR_RUNLOCK(ifp);
  
          return ((struct in6_ifaddr *)ifa);
  }
  
  
  /*
   * find the internet address corresponding to a given interface and address.
   * ifaddr is returned referenced.
   */
  struct in6_ifaddr *
  in6ifa_ifpwithaddr(struct ifnet *ifp, struct in6_addr *addr)
  {
          struct ifaddr *ifa;
  
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  if (IN6_ARE_ADDR_EQUAL(addr, IFA_IN6(ifa))) {
                          ifa_ref(ifa);
                          break;
                  }
          }
          IF_ADDR_RUNLOCK(ifp);
  
          return ((struct in6_ifaddr *)ifa);
  }
  
  /*
   * Find a link-local scoped address on ifp and return it if any.
   */
  struct in6_ifaddr *
  in6ifa_llaonifp(struct ifnet *ifp)
  {
          struct sockaddr_in6 *sin6;
          struct ifaddr *ifa;
  
          if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)
                  return (NULL);
          if_addr_rlock(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  if (ifa->ifa_addr->sa_family != AF_INET6)
                          continue;
                  sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
                  if (IN6_IS_SCOPE_LINKLOCAL(&sin6->sin6_addr) ||
                      IN6_IS_ADDR_MC_INTFACELOCAL(&sin6->sin6_addr) ||
                      IN6_IS_ADDR_MC_NODELOCAL(&sin6->sin6_addr))
                          break;
          }
          if_addr_runlock(ifp);
  
          return ((struct in6_ifaddr *)ifa);
  }
  
  /*
   * Convert IP6 address to printable (loggable) representation. Caller
   * has to make sure that ip6buf is at least INET6_ADDRSTRLEN long.
   */
  static char digits[] = "0123456789abcdef";
  char *
  ip6_sprintf(char *ip6buf, const struct in6_addr *addr)
  {
          int i, cnt = 0, maxcnt = 0, idx = 0, index = 0;
          char *cp;
          const u_int16_t *a = (const u_int16_t *)addr;
          const u_int8_t *d;
          int dcolon = 0, zero = 0;
  
          cp = ip6buf;
  
          for (i = 0; i < 8; i++) {
                  if (*(a + i) == 0) {
                          cnt++;
                          if (cnt == 1)
                                  idx = i;
                  }
                  else if (maxcnt < cnt) {
                          maxcnt = cnt;
                          index = idx;
                          cnt = 0;
                  }
          }
          if (maxcnt < cnt) {
                  maxcnt = cnt;
                  index = idx;
          }
  
          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 && i == index) {
                                  if (i == 0)
                                          *cp++ = ':';
                                  *cp++ = ':';
                                  dcolon = 1;
                          } else {
                                  *cp++ = '';
                                  *cp++ = ':';
                          }
                          a++;
                          continue;
                  }
                  d = (const u_char *)a;
                  /* Try to eliminate leading zeros in printout like in :0001. */
                  zero = 1;
                  *cp = digits[*d >> 4];
                  if (*cp != '') {
                          zero = 0;
                          cp++;
                  }
                  *cp = digits[*d++ & 0xf];
                  if (zero == 0 || (*cp != '')) {
                          zero = 0;
                          cp++;
                  }
                  *cp = digits[*d >> 4];
                  if (zero == 0 || (*cp != '')) {
                          zero = 0;
                          cp++;
                  }
                  *cp++ = digits[*d & 0xf];
                  *cp++ = ':';
                  a++;
          }
          *--cp = '\0';
          return (ip6buf);
  }
  
  int
  in6_localaddr(struct in6_addr *in6)
  {
          struct in6_ifaddr *ia;
  
          if (IN6_IS_ADDR_LOOPBACK(in6) || IN6_IS_ADDR_LINKLOCAL(in6))
                  return 1;
  
          IN6_IFADDR_RLOCK();
          TAILQ_FOREACH(ia, &V_in6_ifaddrhead, ia_link) {
                  if (IN6_ARE_MASKED_ADDR_EQUAL(in6, &ia->ia_addr.sin6_addr,
                      &ia->ia_prefixmask.sin6_addr)) {
                          IN6_IFADDR_RUNLOCK();
                          return 1;
                  }
          }
          IN6_IFADDR_RUNLOCK();
  
          return (0);
  }
  
  /*
   * Return 1 if an internet address is for the local host and configured
   * on one of its interfaces.
   */
  int
  in6_localip(struct in6_addr *in6)
  {
          struct in6_ifaddr *ia;
  
          IN6_IFADDR_RLOCK();
          LIST_FOREACH(ia, IN6ADDR_HASH(in6), ia6_hash) {
                  if (IN6_ARE_ADDR_EQUAL(in6, &ia->ia_addr.sin6_addr)) {
                          IN6_IFADDR_RUNLOCK();
                          return (1);
                  }
          }
          IN6_IFADDR_RUNLOCK();
          return (0);
  }
  
  int
  in6_is_addr_deprecated(struct sockaddr_in6 *sa6)
  {
          struct in6_ifaddr *ia;
  
          IN6_IFADDR_RLOCK();
          LIST_FOREACH(ia, IN6ADDR_HASH(&sa6->sin6_addr), ia6_hash) {
                  if (IN6_ARE_ADDR_EQUAL(IA6_IN6(ia), &sa6->sin6_addr)) {
                          if (ia->ia6_flags & IN6_IFF_DEPRECATED) {
                                  IN6_IFADDR_RUNLOCK();
                                  return (1); /* true */
                          }
                          break;
                  }
          }
          IN6_IFADDR_RUNLOCK();
  
          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 += 8;
          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 (0 > len || len > 128) {
                  log(LOG_ERR, "in6_are_prefix_equal: invalid prefix length(%d)\n",
                      len);
                  return (0);
          }
  
          bytelen = len / 8;
          bitlen = len % 8;
  
          if (bcmp(&p1->s6_addr, &p2->s6_addr, bytelen))
                  return (0);
          if (bitlen != 0 &&
              p1->s6_addr[bytelen] >> (8 - bitlen) !=
              p2->s6_addr[bytelen] >> (8 - bitlen))
                  return (0);
  
          return (1);
  }
  
  void
  in6_prefixlen2mask(struct in6_addr *maskp, int len)
  {
          u_char maskarray[8] = {0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};
          int bytelen, bitlen, i;
  
          /* sanity check */
          if (0 > len || len > 128) {
                  log(LOG_ERR, "in6_prefixlen2mask: invalid prefix length(%d)\n",
                      len);
                  return;
          }
  
          bzero(maskp, sizeof(*maskp));
          bytelen = len / 8;
          bitlen = len % 8;
          for (i = 0; i < bytelen; i++)
                  maskp->s6_addr[i] = 0xff;
          if (bitlen)
                  maskp->s6_addr[bytelen] = maskarray[bitlen - 1];
  }
  
  /*
   * return the best address out of the same scope. 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.
           */
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  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 (V_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) {
                  ifa_ref(&besta->ia_ifa);
                  IF_ADDR_RUNLOCK(ifp);
                  return (besta);
          }
  
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  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 (V_ip6_use_deprecated)
                                  dep[1] = (struct in6_ifaddr *)ifa;
                          continue;
                  }
  
                  if (ifa != NULL)
                          ifa_ref(ifa);
                  IF_ADDR_RUNLOCK(ifp);
                  return (struct in6_ifaddr *)ifa;
          }
  
          /* use the last-resort values, that are, deprecated addresses */
          if (dep[0]) {
                  ifa_ref((struct ifaddr *)dep[0]);
                  IF_ADDR_RUNLOCK(ifp);
                  return dep[0];
          }
          if (dep[1]) {
                  ifa_ref((struct ifaddr *)dep[1]);
                  IF_ADDR_RUNLOCK(ifp);
                  return dep[1];
          }
  
          IF_ADDR_RUNLOCK(ifp);
          return NULL;
  }
  
  /*
   * perform DAD when interface becomes IFF_UP.
   */
  void
  in6_if_up(struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          struct in6_ifaddr *ia;
  
          IF_ADDR_RLOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  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));
                  }
          }
          IF_ADDR_RUNLOCK(ifp);
  
          /*
           * 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);
  
          if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) ||
              (ND_IFINFO(ifp)->flags & ND6_IFF_NO_DAD))
                  return (0);
  
          switch (ifp->if_type) {
  #ifdef IFT_DUMMY
          case IFT_DUMMY:
  #endif
          case IFT_FAITH:
                  /*
                   * These interfaces do not have the IFF_LOOPBACK flag,
                   * but loop packets back.  We do not have to do DAD on such
                   * interfaces.  We should even omit it, because loop-backed
                   * NS would confuse the DAD procedure.
                   */
                  return (0);
          default:
                  /*
                   * Our DAD routine requires the interface up and running.
                   * However, some interfaces can be up before the RUNNING
                   * status.  Additionaly, users may try to assign addresses
                   * before the interface becomes up (or running).
                   * We simply skip DAD in such a case as a work around.
                   * XXX: we should rather mark "tentative" on such addresses,
                   * and do DAD after the interface becomes ready.
                   */
                  if (!((ifp->if_flags & IFF_UP) &&
                      (ifp->if_drv_flags & IFF_DRV_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;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_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);
          }
          IFNET_RUNLOCK_NOSLEEP();
          if (maxmtu)     /* update only when maxmtu is positive */
                  V_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 */
  #ifdef IFT_PROPVIRTUAL
          case IFT_PROPVIRTUAL:   /* XXX: no RFC. treat it as ether */
  #endif
  #ifdef IFT_L2VLAN
          case IFT_L2VLAN:        /* ditto */
  #endif
  #ifdef IFT_IEEE80211
          case IFT_IEEE80211:     /* ditto */
  #endif
  #ifdef IFT_MIP
          case IFT_MIP:   /* ditto */
  #endif
          case IFT_INFINIBAND:
                  return (64);
          case IFT_FDDI:          /* RFC2467 */
                  return (64);
          case IFT_ISO88025:      /* RFC2470 (IPv6 over Token Ring) */
                  return (64);
          case IFT_PPP:           /* RFC2472 */
                  return (64);
          case IFT_ARCNET:        /* RFC2497 */
                  return (64);
          case IFT_FRELAY:        /* RFC2590 */
                  return (64);
          case IFT_IEEE1394:      /* RFC3146 */
                  return (64);
          case IFT_GIF:
                  return (64);    /* draft-ietf-v6ops-mech-v2-07 */
          case IFT_LOOP:
                  return (64);    /* XXX: is this really correct? */
          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);
          }
  }
  
  #include <sys/sysctl.h>
  
  struct in6_llentry {
          struct llentry          base;
          struct sockaddr_in6     l3_addr6;
  };
  
  /*
   * Deletes an address from the address table.
   * This function is called by the timer functions
   * such as arptimer() and nd6_llinfo_timer(), and
   * the caller does the locking.
   */
  static void
  in6_lltable_free(struct lltable *llt, struct llentry *lle)
  {
          LLE_WUNLOCK(lle);
          LLE_LOCK_DESTROY(lle);
          free(lle, M_LLTABLE);
  }
  
  static struct llentry *
  in6_lltable_new(const struct sockaddr *l3addr, u_int flags)
  {
          struct in6_llentry *lle;
  
          lle = malloc(sizeof(struct in6_llentry), M_LLTABLE, M_NOWAIT | M_ZERO);
          if (lle == NULL)                /* NB: caller generates msg */
                  return NULL;
  
          lle->l3_addr6 = *(const struct sockaddr_in6 *)l3addr;
          lle->base.lle_refcnt = 1;
          lle->base.lle_free = in6_lltable_free;
          LLE_LOCK_INIT(&lle->base);
          callout_init(&lle->base.ln_timer_ch, 1);
  
          return (&lle->base);
  }
  
  static void
  in6_lltable_prefix_free(struct lltable *llt, const struct sockaddr *prefix,
      const struct sockaddr *mask, u_int flags)
  {
          const struct sockaddr_in6 *pfx = (const struct sockaddr_in6 *)prefix;
          const struct sockaddr_in6 *msk = (const struct sockaddr_in6 *)mask;
          struct llentry *lle, *next;
          int i;
  
          /*
           * (flags & LLE_STATIC) means deleting all entries
           * including static ND6 entries.
           */
          IF_AFDATA_WLOCK(llt->llt_ifp);
          for (i = 0; i < LLTBL_HASHTBL_SIZE; i++) {
                  LIST_FOREACH_SAFE(lle, &llt->lle_head[i], lle_next, next) {
                          if (IN6_ARE_MASKED_ADDR_EQUAL(
                              &satosin6(L3_ADDR(lle))->sin6_addr,
                              &pfx->sin6_addr, &msk->sin6_addr) &&
                              ((flags & LLE_STATIC) ||
                              !(lle->la_flags & LLE_STATIC))) {
                                  LLE_WLOCK(lle);
                                  if (callout_stop(&lle->la_timer))
                                          LLE_REMREF(lle);
                                  llentry_free(lle);
                          }
                  }
          }
          IF_AFDATA_WUNLOCK(llt->llt_ifp);
  }
  
  static int
  in6_lltable_rtcheck(struct ifnet *ifp,
                      u_int flags,
                      const struct sockaddr *l3addr)
  {
          struct rtentry *rt;
          char ip6buf[INET6_ADDRSTRLEN];
  
          KASSERT(l3addr->sa_family == AF_INET6,
              ("sin_family %d", l3addr->sa_family));
  
          /* Our local addresses are always only installed on the default FIB. */
          /* XXX rtalloc1 should take a const param */
          rt = in6_rtalloc1(__DECONST(struct sockaddr *, l3addr), 0, 0,
              RT_DEFAULT_FIB);
          if (rt == NULL || (rt->rt_flags & RTF_GATEWAY) || rt->rt_ifp != ifp) {
                  struct ifaddr *ifa;
                  /*
                   * Create an ND6 cache for an IPv6 neighbor
                   * that is not covered by our own prefix.
                   */
                  /* XXX ifaof_ifpforaddr should take a const param */
                  ifa = ifaof_ifpforaddr(__DECONST(struct sockaddr *, l3addr), ifp);
                  if (ifa != NULL) {
                          ifa_free(ifa);
                          if (rt != NULL)
                                  RTFREE_LOCKED(rt);
                          return 0;
                  }
                  log(LOG_INFO, "IPv6 address: \"%s\" is not on the network\n",
                      ip6_sprintf(ip6buf, &((const struct sockaddr_in6 *)l3addr)->sin6_addr));
                  if (rt != NULL)
                          RTFREE_LOCKED(rt);
                  return EINVAL;
          }
          RTFREE_LOCKED(rt);
          return 0;
  }
  
  static struct llentry *
  in6_lltable_lookup(struct lltable *llt, u_int flags,
          const struct sockaddr *l3addr)
  {
          const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr;
          struct ifnet *ifp = llt->llt_ifp;
          struct llentry *lle;
          struct llentries *lleh;
          u_int hashkey;
  
          IF_AFDATA_LOCK_ASSERT(ifp);
          KASSERT(l3addr->sa_family == AF_INET6,
              ("sin_family %d", l3addr->sa_family));
  
          hashkey = sin6->sin6_addr.s6_addr32[3];
          lleh = &llt->lle_head[LLATBL_HASH(hashkey, LLTBL_HASHMASK)];
          LIST_FOREACH(lle, lleh, lle_next) {
                  struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)L3_ADDR(lle);
                  if (lle->la_flags & LLE_DELETED)
                          continue;
                  if (bcmp(&sa6->sin6_addr, &sin6->sin6_addr,
                      sizeof(struct in6_addr)) == 0)
                          break;
          }
  
          if (lle == NULL) {
                  if (!(flags & LLE_CREATE))
                          return (NULL);
                  IF_AFDATA_WLOCK_ASSERT(ifp);
                  /*
                   * A route that covers the given address must have
                   * been installed 1st because we are doing a resolution,
                   * verify this.
                   */
                  if (!(flags & LLE_IFADDR) &&
                      in6_lltable_rtcheck(ifp, flags, l3addr) != 0)
                          return NULL;
  
                  lle = in6_lltable_new(l3addr, flags);
                  if (lle == NULL) {
                          log(LOG_INFO, "lla_lookup: new lle malloc failed\n");
                          return NULL;
                  }
                  lle->la_flags = flags & ~LLE_CREATE;
                  if ((flags & (LLE_CREATE | LLE_IFADDR)) == (LLE_CREATE | LLE_IFADDR)) {
                          bcopy(IF_LLADDR(ifp), &lle->ll_addr, ifp->if_addrlen);
                          lle->la_flags |= (LLE_VALID | LLE_STATIC);
                  }
  
                  lle->lle_tbl  = llt;
                  lle->lle_head = lleh;
                  lle->la_flags |= LLE_LINKED;
                  LIST_INSERT_HEAD(lleh, lle, lle_next);
          } else if (flags & LLE_DELETE) {
                  if (!(lle->la_flags & LLE_IFADDR) || (flags & LLE_IFADDR)) {
                          LLE_WLOCK(lle);
                          lle->la_flags |= LLE_DELETED;
  #ifdef DIAGNOSTIC
                          log(LOG_INFO, "ifaddr cache = %p is deleted\n", lle);
  #endif
                          if ((lle->la_flags &
                              (LLE_STATIC | LLE_IFADDR)) == LLE_STATIC)
                                  llentry_free(lle);
                          else
                                  LLE_WUNLOCK(lle);
                  }
                  lle = (void *)-1;
          }
          if (LLE_IS_VALID(lle)) {
                  if (flags & LLE_EXCLUSIVE)
                          LLE_WLOCK(lle);
                  else
                          LLE_RLOCK(lle);
          }
          return (lle);
  }
  
  static int
  in6_lltable_dump(struct lltable *llt, struct sysctl_req *wr)
  {
          struct ifnet *ifp = llt->llt_ifp;
          struct llentry *lle;
          /* XXX stack use */
          struct {
                  struct rt_msghdr        rtm;
                  struct sockaddr_in6     sin6;
                  /*
                   * ndp.c assumes that sdl is word aligned
                   */
  #ifdef __LP64__
                  uint32_t                pad;
  #endif
                  struct sockaddr_dl      sdl;
          } ndpc;
          int i, error;
  
          if (ifp->if_flags & IFF_LOOPBACK)
                  return 0;
  
          LLTABLE_LOCK_ASSERT();
  
          error = 0;
          for (i = 0; i < LLTBL_HASHTBL_SIZE; i++) {
                  LIST_FOREACH(lle, &llt->lle_head[i], lle_next) {
                          struct sockaddr_dl *sdl;
  
                          /* skip deleted or invalid entries */
                          if ((lle->la_flags & (LLE_DELETED|LLE_VALID)) != LLE_VALID)
                                  continue;
                          /* Skip if jailed and not a valid IP of the prison. */
                          if (prison_if(wr->td->td_ucred, L3_ADDR(lle)) != 0)
                                  continue;
                          /*
                           * produce a msg made of:
                           *  struct rt_msghdr;
                           *  struct sockaddr_in6 (IPv6)
                           *  struct sockaddr_dl;
                           */
                          bzero(&ndpc, sizeof(ndpc));
                          ndpc.rtm.rtm_msglen = sizeof(ndpc);
                          ndpc.rtm.rtm_version = RTM_VERSION;
                          ndpc.rtm.rtm_type = RTM_GET;
                          ndpc.rtm.rtm_flags = RTF_UP;
                          ndpc.rtm.rtm_addrs = RTA_DST | RTA_GATEWAY;
                          ndpc.sin6.sin6_family = AF_INET6;
                          ndpc.sin6.sin6_len = sizeof(ndpc.sin6);
                          bcopy(L3_ADDR(lle), &ndpc.sin6, L3_ADDR_LEN(lle));
                          if (V_deembed_scopeid)
                                  sa6_recoverscope(&ndpc.sin6);
  
                          /* publish */
                          if (lle->la_flags & LLE_PUB)
                                  ndpc.rtm.rtm_flags |= RTF_ANNOUNCE;
  
                          sdl = &ndpc.sdl;
                          sdl->sdl_family = AF_LINK;
                          sdl->sdl_len = sizeof(*sdl);
                          sdl->sdl_alen = ifp->if_addrlen;
                          sdl->sdl_index = ifp->if_index;
                          sdl->sdl_type = ifp->if_type;
                          bcopy(&lle->ll_addr, LLADDR(sdl), ifp->if_addrlen);
                          ndpc.rtm.rtm_rmx.rmx_expire =
                              lle->la_flags & LLE_STATIC ? 0 : lle->la_expire;
                          ndpc.rtm.rtm_flags |= (RTF_HOST | RTF_LLDATA);
                          if (lle->la_flags & LLE_STATIC)
                                  ndpc.rtm.rtm_flags |= RTF_STATIC;
                          ndpc.rtm.rtm_index = ifp->if_index;
                          error = SYSCTL_OUT(wr, &ndpc, sizeof(ndpc));
                          if (error)
                                  break;
                  }
          }
          return error;
  }
  
  void *
  in6_domifattach(struct ifnet *ifp)
  {
          struct in6_ifextra *ext;
  
          /* There are not IPv6-capable interfaces. */
          switch (ifp->if_type) {
          case IFT_PFLOG:
          case IFT_PFSYNC:
          case IFT_USB:
                  return (NULL);
          }
          ext = (struct in6_ifextra *)malloc(sizeof(*ext), M_IFADDR, M_WAITOK);
          bzero(ext, sizeof(*ext));
  
          ext->in6_ifstat = malloc(sizeof(counter_u64_t) *
              sizeof(struct in6_ifstat) / sizeof(uint64_t), M_IFADDR, M_WAITOK);
          COUNTER_ARRAY_ALLOC(ext->in6_ifstat,
              sizeof(struct in6_ifstat) / sizeof(uint64_t), M_WAITOK);
  
          ext->icmp6_ifstat = malloc(sizeof(counter_u64_t) *
              sizeof(struct icmp6_ifstat) / sizeof(uint64_t), M_IFADDR,
              M_WAITOK);
          COUNTER_ARRAY_ALLOC(ext->icmp6_ifstat,
              sizeof(struct icmp6_ifstat) / sizeof(uint64_t), M_WAITOK);
  
          ext->nd_ifinfo = nd6_ifattach(ifp);
          ext->scope6_id = scope6_ifattach(ifp);
          ext->lltable = lltable_init(ifp, AF_INET6);
          if (ext->lltable != NULL) {
                  ext->lltable->llt_prefix_free = in6_lltable_prefix_free;
                  ext->lltable->llt_lookup = in6_lltable_lookup;
                  ext->lltable->llt_dump = in6_lltable_dump;
          }
  
          ext->mld_ifinfo = mld_domifattach(ifp);
  
          return ext;
  }
  
  void
  in6_domifdetach(struct ifnet *ifp, void *aux)
  {
          struct in6_ifextra *ext = (struct in6_ifextra *)aux;
  
          mld_domifdetach(ifp);
          scope6_ifdetach(ext->scope6_id);
          nd6_ifdetach(ext->nd_ifinfo);
          lltable_free(ext->lltable);
          COUNTER_ARRAY_FREE(ext->in6_ifstat,
              sizeof(struct in6_ifstat) / sizeof(uint64_t));
          free(ext->in6_ifstat, M_IFADDR);
          COUNTER_ARRAY_FREE(ext->icmp6_ifstat,
              sizeof(struct icmp6_ifstat) / sizeof(uint64_t));
          free(ext->icmp6_ifstat, M_IFADDR);
          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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