/*      $NetBSD: in6.c,v 1.293 2025/06/05 06:30:10 ozaki-r Exp $        */
/*      $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $   */

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

/*
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)in.c        8.2 (Berkeley) 11/15/93
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.293 2025/06/05 06:30:10 ozaki-r Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#include "opt_compat_netbsd.h"
#include "opt_net_mpsafe.h"
#endif

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sockio.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/kauth.h>
#include <sys/cprng.h>
#include <sys/kmem.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/if_llatbl.h>
#include <net/if_ether.h>
#include <net/if_dl.h>
#include <net/pfil.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_var.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 <compat/netinet6/in6_var.h>
#include <compat/netinet6/nd6.h>

MALLOC_DEFINE(M_IP6OPT, "ip6_options", "IPv6 options");

/* enable backward compatibility code for obsoleted ioctls */
#define COMPAT_IN6IFIOCTL

#ifdef  IN6_DEBUG
#define IN6_DPRINTF(__fmt, ...) printf(__fmt, __VA_ARGS__)
#else
#define IN6_DPRINTF(__fmt, ...) do { } while (/*CONSTCOND*/0) 
#endif /* IN6_DEBUG */

/*
 * Definitions of some constant IP6 addresses.
 */
const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
const struct in6_addr in6addr_nodelocal_allnodes =
        IN6ADDR_NODELOCAL_ALLNODES_INIT;
const struct in6_addr in6addr_linklocal_allnodes =
        IN6ADDR_LINKLOCAL_ALLNODES_INIT;
const struct in6_addr in6addr_linklocal_allrouters =
        IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;

const struct in6_addr in6mask0 = IN6MASK0;
const struct in6_addr in6mask32 = IN6MASK32;
const struct in6_addr in6mask64 = IN6MASK64;
const struct in6_addr in6mask96 = IN6MASK96;
const struct in6_addr in6mask128 = IN6MASK128;

const struct sockaddr_in6 sa6_any = {sizeof(sa6_any), AF_INET6,
                                     0, 0, IN6ADDR_ANY_INIT, 0};

struct pslist_head      in6_ifaddr_list;
kmutex_t                in6_ifaddr_lock;

static int in6_lifaddr_ioctl(struct socket *, u_long, void *,
        struct ifnet *);
static int in6_ifaddprefix(struct in6_ifaddr *);
static int in6_ifremprefix(struct in6_ifaddr *);
static int in6_ifinit(struct ifnet *, struct in6_ifaddr *,
        const struct sockaddr_in6 *, int);
static void in6_unlink_ifa(struct in6_ifaddr *, struct ifnet *);
static int in6_update_ifa1(struct ifnet *, struct in6_aliasreq *,
    struct in6_ifaddr **, struct psref *, int);

void
in6_init(void)
{

        PSLIST_INIT(&in6_ifaddr_list);
        mutex_init(&in6_ifaddr_lock, MUTEX_DEFAULT, IPL_NONE);

        in6_sysctl_multicast_setup(NULL);
}

/*
 * Add ownaddr as loopback rtentry.  We previously add the route only if
 * necessary (ex. on a p2p link).  However, since we now manage addresses
 * separately from prefixes, we should always add the route.  We can't
 * rely on the cloning mechanism from the corresponding interface route
 * any more.
 */
void
in6_ifaddlocal(struct ifaddr *ifa)
{

        if (IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &in6addr_any) ||
            (ifa->ifa_ifp->if_flags & IFF_POINTOPOINT &&
            IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), IFA_DSTIN6(ifa))))
        {
                rt_addrmsg(RTM_NEWADDR, ifa);
                return;
        }

        rt_ifa_addlocal(ifa);
}

/*
 * Remove loopback rtentry of ownaddr generated by in6_ifaddlocal(),
 * if it exists.
 */
void
in6_ifremlocal(struct ifaddr *ifa)
{
        struct in6_ifaddr *ia;
        struct ifaddr *alt_ifa = NULL;
        int ia_count = 0;
        struct psref psref;
        int s;

        /*
         * Some of BSD variants do not remove cloned routes
         * from an interface direct route, when removing the direct route
         * (see comments in net/net_osdep.h).  Even for variants that do remove
         * cloned routes, they could fail to remove the cloned routes when
         * we handle multiple addresses that share a common prefix.
         * So, we should remove the route corresponding to the deleted address.
         */

        /*
         * Delete the entry only if exactly one ifaddr matches the
         * address, ifa->ifa_addr.
         *
         * If more than one ifaddr matches, replace the ifaddr in
         * the routing table, rt_ifa, with a different ifaddr than
         * the one we are purging, ifa.  It is important to do
         * this, or else the routing table can accumulate dangling
         * pointers rt->rt_ifa->ifa_ifp to destroyed interfaces,
         * which will lead to crashes, later.  (More than one ifaddr
         * can match if we assign the same address to multiple---probably
         * p2p---interfaces.)
         *
         * XXX An old comment at this place said, "we should avoid
         * XXX such a configuration [i.e., interfaces with the same
         * XXX addressed assigned --ed.] in IPv6...".  I do not
         * XXX agree, especially now that I have fixed the dangling
         * XXX ifp-pointers bug.
         */
        s = pserialize_read_enter();
        IN6_ADDRLIST_READER_FOREACH(ia) {
                if (!IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &ia->ia_addr.sin6_addr))
                        continue;
                if (ia->ia_ifp != ifa->ifa_ifp)
                        alt_ifa = &ia->ia_ifa;
                if (++ia_count > 1 && alt_ifa != NULL)
                        break;
        }
        if (ia_count > 1 && alt_ifa != NULL)
                ifa_acquire(alt_ifa, &psref);
        pserialize_read_exit(s);

        if (ia_count == 0)
                return;

        rt_ifa_remlocal(ifa, ia_count == 1 ? NULL : alt_ifa);

        if (ia_count > 1 && alt_ifa != NULL)
                ifa_release(alt_ifa, &psref);
}

/* Add prefix route for the network. */
static int
in6_ifaddprefix(struct in6_ifaddr *ia)
{
        int error, flags = 0;

        if (in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL) == 128) {
                if (ia->ia_dstaddr.sin6_family != AF_INET6)
                        /* We don't need to install a host route. */
                        return 0;
                flags |= RTF_HOST;
        }

        /* Is this a connected route for neighbour discovery? */
        if (nd6_need_cache(ia->ia_ifp))
                flags |= RTF_CONNECTED;

        if ((error = rtinit(&ia->ia_ifa, RTM_ADD, RTF_UP | flags)) == 0)
                ia->ia_flags |= IFA_ROUTE;
        else if (error == EEXIST)
                /* Existence of the route is not an error. */
                error = 0;

        return error;
}

static int
in6_rt_ifa_matcher(struct rtentry *rt, void *v)
{
        struct ifaddr *ifa = v;

        if (rt->rt_ifa == ifa)
                return 1;
        else
                return 0;
}

/* Delete network prefix route if present.
 * Re-add it to another address if the prefix matches. */
static int
in6_ifremprefix(struct in6_ifaddr *target)
{
        int error, s;
        struct in6_ifaddr *ia;

        if ((target->ia_flags & IFA_ROUTE) == 0)
                return 0;

        s = pserialize_read_enter();
        IN6_ADDRLIST_READER_FOREACH(ia) {
                if (target->ia_dstaddr.sin6_len) {
                        if (ia->ia_dstaddr.sin6_len == 0 ||
                            !IN6_ARE_ADDR_EQUAL(&ia->ia_dstaddr.sin6_addr,
                            &target->ia_dstaddr.sin6_addr))
                                continue;
                } else {
                        if (!IN6_ARE_MASKED_ADDR_EQUAL(&ia->ia_addr.sin6_addr,
                            &target->ia_addr.sin6_addr,
                            &target->ia_prefixmask.sin6_addr))
                                continue;
                }

                /*
                 * if we got a matching prefix route, move IFA_ROUTE to him
                 */
                if ((ia->ia_flags & IFA_ROUTE) == 0) {
                        struct psref psref;
                        int bound = curlwp_bind();

                        ia6_acquire(ia, &psref);
                        pserialize_read_exit(s);

                        rtinit(&target->ia_ifa, RTM_DELETE, 0);
                        target->ia_flags &= ~IFA_ROUTE;

                        error = in6_ifaddprefix(ia);

                        if (!ISSET(target->ia_ifa.ifa_flags, IFA_DESTROYING))
                                goto skip;
                        /*
                         * Replace rt_ifa of routes that have the removing address
                         * with the new address.
                         */
                        rt_replace_ifa_matched_entries(AF_INET6,
                            in6_rt_ifa_matcher, &target->ia_ifa, &ia->ia_ifa);

                skip:
                        ia6_release(ia, &psref);
                        curlwp_bindx(bound);

                        return error;
                }
        }
        pserialize_read_exit(s);

        /*
         * noone seem to have prefix route.  remove it.
         */
        rtinit(&target->ia_ifa, RTM_DELETE, 0);
        target->ia_flags &= ~IFA_ROUTE;

        if (ISSET(target->ia_ifa.ifa_flags, IFA_DESTROYING)) {
                /* Remove routes that have the removing address as rt_ifa. */
                rt_delete_matched_entries(AF_INET6, in6_rt_ifa_matcher,
                    &target->ia_ifa, true);
        }

        return 0;
}

int
in6_mask2len(struct in6_addr *mask, u_char *lim0)
{
        int x = 0, y;
        u_char *lim = lim0, *p;

        /* ignore the scope_id part */
        if (lim0 == NULL || lim0 - (u_char *)mask > sizeof(*mask))
                lim = (u_char *)mask + sizeof(*mask);
        for (p = (u_char *)mask; p < lim; x++, p++) {
                if (*p != 0xff)
                        break;
        }
        y = 0;
        if (p < lim) {
                for (y = 0; y < NBBY; y++) {
                        if ((*p & (0x80 >> y)) == 0)
                                break;
                }
        }

        /*
         * when the limit pointer is given, do a stricter check on the
         * remaining bits.
         */
        if (p < lim) {
                if (y != 0 && (*p & (0x00ff >> y)) != 0)
                        return -1;
                for (p = p + 1; p < lim; p++)
                        if (*p != 0)
                                return -1;
        }

        return x * NBBY + y;
}

#define ifa2ia6(ifa)    ((struct in6_ifaddr *)(ifa))
#define ia62ifa(ia6)    (&((ia6)->ia_ifa))

static int
in6_control1(struct socket *so, u_long cmd, void *data, struct ifnet *ifp)
{
        struct  in6_ifreq *ifr = (struct in6_ifreq *)data;
        struct  in6_ifaddr *ia = NULL;
        struct  in6_aliasreq *ifra = (struct in6_aliasreq *)data;
        struct sockaddr_in6 *sa6;
        int error, bound;
        struct psref psref;

        switch (cmd) {
        case SIOCAADDRCTL_POLICY:
        case SIOCDADDRCTL_POLICY:
                /* Privileged. */
                return in6_src_ioctl(cmd, data);
        /*
         * XXX: Fix me, once we fix SIOCSIFADDR, SIOCIFDSTADDR, etc.
         */
        case SIOCSIFADDR:
        case SIOCSIFDSTADDR:
        case SIOCSIFBRDADDR:
        case SIOCSIFNETMASK:
                return EOPNOTSUPP;
        case SIOCGETSGCNT_IN6:
        case SIOCGETMIFCNT_IN6:
                return mrt6_ioctl(cmd, data);
        case SIOCGIFADDRPREF:
        case SIOCSIFADDRPREF:
                if (ifp == NULL)
                        return EINVAL;
                return ifaddrpref_ioctl(so, cmd, data, ifp);
        }

        if (ifp == NULL)
                return EOPNOTSUPP;

        switch (cmd) {
#ifdef OSIOCSIFINFO_IN6_90
        case OSIOCSIFINFO_FLAGS_90:
        case OSIOCSIFINFO_IN6_90:
        case OSIOCSDEFIFACE_IN6:
        case OSIOCSNDFLUSH_IN6:
        case OSIOCSPFXFLUSH_IN6:
        case OSIOCSRTRFLUSH_IN6:
#endif
        case SIOCSIFINFO_FLAGS:
        case SIOCSIFINFO_IN6:
                /* Privileged. */
                /* FALLTHROUGH */
#ifdef OSIOCGIFINFO_IN6
        case OSIOCGIFINFO_IN6:
#endif
#ifdef OSIOCGIFINFO_IN6_90
        case OSIOCGDRLST_IN6:
        case OSIOCGPRLST_IN6:
        case OSIOCGIFINFO_IN6_90:
        case OSIOCGDEFIFACE_IN6:
#endif
        case SIOCGIFINFO_IN6:
        case SIOCGNBRINFO_IN6:
                return nd6_ioctl(cmd, data, ifp);
        }

        switch (cmd) {
        case SIOCALIFADDR:
        case SIOCDLIFADDR:
                /* Privileged. */
                /* FALLTHROUGH */
        case SIOCGLIFADDR:
                return in6_lifaddr_ioctl(so, cmd, data, ifp);
        }

        /*
         * 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:
#ifdef OSIOCAIFADDR_IN6
        case OSIOCAIFADDR_IN6:
#endif
#ifdef OSIOCSIFPHYADDR_IN6
        case OSIOCSIFPHYADDR_IN6:
#endif
        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 SIOCGIFALIFETIME_IN6:
#ifdef OSIOCGIFALIFETIME_IN6
        case OSIOCGIFALIFETIME_IN6:
#endif
        case SIOCGIFSTAT_IN6:
        case SIOCGIFSTAT_ICMP6:
                sa6 = &ifr->ifr_addr;
                break;
        default:
                sa6 = NULL;
                break;
        }

        error = 0;
        bound = curlwp_bind();
        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)
                        goto out;
                ia = in6ifa_ifpwithaddr_psref(ifp, &sa6->sin6_addr, &psref);
        } 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.
                 */
                error = EINVAL;
                goto release;

        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;
                }
#ifdef OSIOCAIFADDR_IN6
                /* FALLTHROUGH */
        case OSIOCAIFADDR_IN6:
#endif
                /* 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 release;
                }
                /* Privileged. */

                break;

        case SIOCGIFADDR_IN6:
                /* This interface is basically deprecated. use SIOCGIFCONF. */
                /* FALLTHROUGH */
        case SIOCGIFAFLAG_IN6:
        case SIOCGIFNETMASK_IN6:
        case SIOCGIFDSTADDR_IN6:
        case SIOCGIFALIFETIME_IN6:
#ifdef OSIOCGIFALIFETIME_IN6
        case OSIOCGIFALIFETIME_IN6:
#endif
                /* must think again about its semantics */
                if (ia == NULL) {
                        error = EADDRNOTAVAIL;
                        goto out;
                }
                break;
        }

        switch (cmd) {

        case SIOCGIFADDR_IN6:
                ifr->ifr_addr = ia->ia_addr;
                error = sa6_recoverscope(&ifr->ifr_addr);
                break;

        case SIOCGIFDSTADDR_IN6:
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0) {
                        error = EINVAL;
                        break;
                }
                /*
                 * XXX: should we check if ifa_dstaddr is NULL and return
                 * an error?
                 */
                ifr->ifr_dstaddr = ia->ia_dstaddr;
                error = sa6_recoverscope(&ifr->ifr_dstaddr);
                break;

        case SIOCGIFNETMASK_IN6:
                ifr->ifr_addr = ia->ia_prefixmask;
                break;

        case SIOCGIFAFLAG_IN6:
                ifr->ifr_ifru.ifru_flags6 = ia->ia6_flags;
                break;

        case SIOCGIFSTAT_IN6:
                if (ifp == NULL) {
                        error = EINVAL;
                        break;
                }
                memset(&ifr->ifr_ifru.ifru_stat, 0,
                    sizeof(ifr->ifr_ifru.ifru_stat));
                ifr->ifr_ifru.ifru_stat =
                    *((struct in6_ifextra *)ifp->if_afdata[AF_INET6])->in6_ifstat;
                break;

        case SIOCGIFSTAT_ICMP6:
                if (ifp == NULL) {
                        error = EINVAL;
                        break;
                }
                memset(&ifr->ifr_ifru.ifru_icmp6stat, 0,
                    sizeof(ifr->ifr_ifru.ifru_icmp6stat));
                ifr->ifr_ifru.ifru_icmp6stat =
                    *((struct in6_ifextra *)ifp->if_afdata[AF_INET6])->icmp6_ifstat;
                break;

#ifdef OSIOCGIFALIFETIME_IN6
        case OSIOCGIFALIFETIME_IN6:
#endif
        case SIOCGIFALIFETIME_IN6:
                ifr->ifr_ifru.ifru_lifetime = ia->ia6_lifetime;
                if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                        time_t maxexpire;
                        struct in6_addrlifetime *retlt =
                            &ifr->ifr_ifru.ifru_lifetime;

                        /*
                         * XXX: adjust expiration time assuming time_t is
                         * signed.
                         */
                        maxexpire = ((time_t)~0) &
                            (time_t)~(1ULL << ((sizeof(maxexpire) * NBBY) - 1));
                        if (ia->ia6_lifetime.ia6t_vltime <
                            maxexpire - ia->ia6_updatetime) {
                                retlt->ia6t_expire = ia->ia6_updatetime +
                                    ia->ia6_lifetime.ia6t_vltime;
                                retlt->ia6t_expire = retlt->ia6t_expire ?
                                    time_mono_to_wall(retlt->ia6t_expire) :
                                    0;
                        } else
                                retlt->ia6t_expire = maxexpire;
                }
                if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                        time_t maxexpire;
                        struct in6_addrlifetime *retlt =
                            &ifr->ifr_ifru.ifru_lifetime;

                        /*
                         * XXX: adjust expiration time assuming time_t is
                         * signed.
                         */
                        maxexpire = ((time_t)~0) &
                            (time_t)~(1ULL << ((sizeof(maxexpire) * NBBY) - 1));
                        if (ia->ia6_lifetime.ia6t_pltime <
                            maxexpire - ia->ia6_updatetime) {
                                retlt->ia6t_preferred = ia->ia6_updatetime +
                                    ia->ia6_lifetime.ia6t_pltime;
                                retlt->ia6t_preferred = retlt->ia6t_preferred ?
                                    time_mono_to_wall(retlt->ia6t_preferred) :
                                    0;
                        } else
                                retlt->ia6t_preferred = maxexpire;
                }
#ifdef OSIOCFIFALIFETIME_IN6
                if (cmd == OSIOCFIFALIFETIME_IN6)
                        in6_addrlifetime_to_in6_addrlifetime50(
                            &ifr->ifru.ifru_lifetime);
#endif
                break;

#ifdef OSIOCAIFADDR_IN6
        case OSIOCAIFADDR_IN6:
                in6_aliasreq50_to_in6_aliasreq(ifra);
#endif
                /*FALLTHROUGH*/
        case SIOCAIFADDR_IN6:
        {
                struct in6_addrlifetime *lt;

                /* reject read-only flags */
                if ((ifra->ifra_flags & IN6_IFF_DUPLICATED) != 0 ||
                    (ifra->ifra_flags & IN6_IFF_DETACHED) != 0 ||
                    (ifra->ifra_flags & IN6_IFF_TENTATIVE) != 0 ||
                    (ifra->ifra_flags & IN6_IFF_NODAD) != 0) {
                        error = EINVAL;
                        break;
                }
                /*
                 * ia6t_expire and ia6t_preferred won't be used for now,
                 * so just in case.
                 */
                lt = &ifra->ifra_lifetime;
                if (lt->ia6t_expire != 0)
                        lt->ia6t_expire = time_wall_to_mono(lt->ia6t_expire);
                if (lt->ia6t_preferred != 0)
                        lt->ia6t_preferred =
                            time_wall_to_mono(lt->ia6t_preferred);
                /*
                 * make (ia == NULL) or update (ia != NULL) the interface
                 * address structure, and link it to the list.
                 */
                int s = splsoftnet();
                error = in6_update_ifa1(ifp, ifra, &ia, &psref, 0);
                splx(s);
                /*
                 * in6_update_ifa1 doesn't create the address if its
                 * valid lifetime (vltime) is zero, since we would just
                 * delete the address immediately in that case anyway.
                 * So it may succeed but return null ia.  In that case,
                 * nothing left to do.
                 */
                if (error || ia == NULL)
                        break;
                pfil_run_addrhooks(if_pfil, cmd, &ia->ia_ifa);
                break;
        }

        case SIOCDIFADDR_IN6:
                ia6_release(ia, &psref);
                ifaref(&ia->ia_ifa);
                in6_purgeaddr(&ia->ia_ifa);
                pfil_run_addrhooks(if_pfil, cmd, &ia->ia_ifa);
                ifafree(&ia->ia_ifa);
                ia = NULL;
                break;

        default:
                error = ENOTTY;
        }
release:
        ia6_release(ia, &psref);
out:
        curlwp_bindx(bound);
        return error;
}

int
in6_control(struct socket *so, u_long cmd, void *data, struct ifnet *ifp)
{
        int error, s;

        switch (cmd) {
#ifdef OSIOCSIFINFO_IN6_90
        case OSIOCSIFINFO_FLAGS_90:
        case OSIOCSIFINFO_IN6_90:
        case OSIOCSDEFIFACE_IN6:
        case OSIOCSNDFLUSH_IN6:
        case OSIOCSPFXFLUSH_IN6:
        case OSIOCSRTRFLUSH_IN6:
#endif
        case SIOCSIFINFO_FLAGS:
        case SIOCSIFINFO_IN6:

        case SIOCALIFADDR:
        case SIOCDLIFADDR:

        case SIOCDIFADDR_IN6:
#ifdef OSIOCAIFADDR_IN6
        case OSIOCAIFADDR_IN6:
#endif
        case SIOCAIFADDR_IN6:

        case SIOCAADDRCTL_POLICY:
        case SIOCDADDRCTL_POLICY:

                if (kauth_authorize_network(kauth_cred_get(),
                    KAUTH_NETWORK_SOCKET,
                    KAUTH_REQ_NETWORK_SOCKET_SETPRIV,
                    so, NULL, NULL))
                        return EPERM;
                break;
        }

        s = splsoftnet();
#ifndef NET_MPSAFE
        KASSERT(KERNEL_LOCKED_P());
#endif
        error = in6_control1(so , cmd, data, ifp);
        splx(s);
        return error;
}

static int
in6_get_llsol_addr(struct in6_addr *llsol, struct ifnet *ifp,
    struct in6_addr *ip6)
{
        int error;

        memset(llsol, 0, sizeof(struct in6_addr));
        llsol->s6_addr16[0] = htons(0xff02);
        llsol->s6_addr32[1] = 0;
        llsol->s6_addr32[2] = htonl(1);
        llsol->s6_addr32[3] = ip6->s6_addr32[3];
        llsol->s6_addr8[12] = 0xff;

        error = in6_setscope(llsol, ifp, NULL);
        if (error != 0) {
                /* XXX: should not happen */
                log(LOG_ERR, "%s: in6_setscope failed\n", __func__);
        }

        return error;
}

static int
in6_join_mcastgroups(struct in6_aliasreq *ifra, struct in6_ifaddr *ia,
    struct ifnet *ifp, int flags)
{
        int error;
        struct sockaddr_in6 mltaddr, mltmask;
        struct in6_multi_mship *imm;
        struct in6_addr llsol;
        struct rtentry *rt;
        int dad_delay;
        char ip6buf[INET6_ADDRSTRLEN];

        /* join solicited multicast addr for new host id */
        error = in6_get_llsol_addr(&llsol, ifp, &ifra->ifra_addr.sin6_addr);
        if (error != 0)
                goto out;
        dad_delay = 0;
        if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                /*
                 * We need a random delay for DAD on the address
                 * being configured.  It also means delaying
                 * transmission of the corresponding MLD report to
                 * avoid report collision.
                 * [draft-ietf-ipv6-rfc2462bis-02.txt]
                 */
                dad_delay = cprng_fast32() % (MAX_RTR_SOLICITATION_DELAY * hz);
        }

#define MLTMASK_LEN  4  /* mltmask's masklen (=32bit=4octet) */
        /* join solicited multicast addr for new host id */
        imm = in6_joingroup(ifp, &llsol, &error, dad_delay);
        if (!imm) {
                nd6log(LOG_ERR,
                    "addmulti failed for %s on %s (errno=%d)\n",
                    IN6_PRINT(ip6buf, &llsol), if_name(ifp), error);
                goto out;
        }
        mutex_enter(&in6_ifaddr_lock);
        LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
        mutex_exit(&in6_ifaddr_lock);

        sockaddr_in6_init(&mltmask, &in6mask32, 0, 0, 0);

        /*
         * join link-local all-nodes address
         */
        sockaddr_in6_init(&mltaddr, &in6addr_linklocal_allnodes,
            0, 0, 0);
        if ((error = in6_setscope(&mltaddr.sin6_addr, ifp, NULL)) != 0)
                goto out; /* XXX: should not fail */

        /*
         * XXX: do we really need this automatic routes?
         * We should probably reconsider this stuff.  Most applications
         * actually do not need the routes, since they usually specify
         * the outgoing interface.
         */
        rt = rtalloc1(sin6tosa(&mltaddr), 0);
        if (rt) {
                if (memcmp(&mltaddr.sin6_addr,
                    &satocsin6(rt_getkey(rt))->sin6_addr,
                    MLTMASK_LEN)) {
                        rt_unref(rt);
                        rt = NULL;
                } else if (rt->rt_ifp != ifp) {
                        IN6_DPRINTF("%s: rt_ifp %p -> %p (%s) "
                            "network %04x:%04x::/32 = %04x:%04x::/32\n",
                            __func__, rt->rt_ifp, ifp, ifp->if_xname,
                            ntohs(mltaddr.sin6_addr.s6_addr16[0]),
                            ntohs(mltaddr.sin6_addr.s6_addr16[1]),
                            satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[0],
                            satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[1]);
#ifdef NET_MPSAFE
                        error = rt_update_prepare(rt);
                        if (error == 0) {
                                rt_replace_ifa(rt, &ia->ia_ifa);
                                rt->rt_ifp = ifp;
                                rt_update_finish(rt);
                        } else {
                                /*
                                 * If error != 0, the rtentry is being
                                 * destroyed, so doing nothing doesn't
                                 * matter.
                                 */
                        }
#else
                        rt_replace_ifa(rt, &ia->ia_ifa);
                        rt->rt_ifp = ifp;
#endif
                }
        }
        if (!rt) {
                struct rt_addrinfo info;

                memset(&info, 0, sizeof(info));
                info.rti_info[RTAX_DST] = sin6tosa(&mltaddr);
                info.rti_info[RTAX_GATEWAY] = sin6tosa(&ia->ia_addr);
                info.rti_info[RTAX_NETMASK] = sin6tosa(&mltmask);
                info.rti_info[RTAX_IFA] = sin6tosa(&ia->ia_addr);
                /* XXX: we need RTF_CONNECTED to fake nd6_rtrequest */
                info.rti_flags = RTF_UP | RTF_CONNECTED;
                error = rtrequest1(RTM_ADD, &info, NULL);
                if (error)
                        goto out;
        } else {
                rt_unref(rt);
        }
        imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
        if (!imm) {
                nd6log(LOG_WARNING,
                    "addmulti failed for %s on %s (errno=%d)\n",
                    IN6_PRINT(ip6buf, &mltaddr.sin6_addr),
                    if_name(ifp), error);
                goto out;
        }
        mutex_enter(&in6_ifaddr_lock);
        LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
        mutex_exit(&in6_ifaddr_lock);

        /*
         * join node information group address
         */
        dad_delay = 0;
        if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                /*
                 * The spec doesn't say anything about delay for this
                 * group, but the same logic should apply.
                 */
                dad_delay = cprng_fast32() % (MAX_RTR_SOLICITATION_DELAY * hz);
        }
        if (in6_nigroup(ifp, hostname, hostnamelen, &mltaddr) != 0)
                ;
        else if ((imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error,
                  dad_delay)) == NULL) { /* XXX jinmei */
                nd6log(LOG_WARNING,
                    "addmulti failed for %s on %s (errno=%d)\n",
                    IN6_PRINT(ip6buf, &mltaddr.sin6_addr),
                    if_name(ifp), error);
                /* XXX not very fatal, go on... */
        } else {
                mutex_enter(&in6_ifaddr_lock);
                LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
                mutex_exit(&in6_ifaddr_lock);
        }


        /*
         * 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 out; /* XXX: should not fail */

        /* XXX: again, do we really need the route? */
        rt = rtalloc1(sin6tosa(&mltaddr), 0);
        if (rt) {
                /* 32bit came from "mltmask" */
                if (memcmp(&mltaddr.sin6_addr,
                    &satocsin6(rt_getkey(rt))->sin6_addr,
                    32 / NBBY)) {
                        rt_unref(rt);
                        rt = NULL;
                } else if (rt->rt_ifp != ifp) {
                        IN6_DPRINTF("%s: rt_ifp %p -> %p (%s) "
                            "network %04x:%04x::/32 = %04x:%04x::/32\n",
                            __func__, rt->rt_ifp, ifp, ifp->if_xname,
                            ntohs(mltaddr.sin6_addr.s6_addr16[0]),
                            ntohs(mltaddr.sin6_addr.s6_addr16[1]),
                            satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[0],
                            satocsin6(rt_getkey(rt))->sin6_addr.s6_addr16[1]);
#ifdef NET_MPSAFE
                        error = rt_update_prepare(rt);
                        if (error == 0) {
                                rt_replace_ifa(rt, &ia->ia_ifa);
                                rt->rt_ifp = ifp;
                                rt_update_finish(rt);
                        } else {
                                /*
                                 * If error != 0, the rtentry is being
                                 * destroyed, so doing nothing doesn't
                                 * matter.
                                 */
                        }
#else
                        rt_replace_ifa(rt, &ia->ia_ifa);
                        rt->rt_ifp = ifp;
#endif
                }
        }
        if (!rt) {
                struct rt_addrinfo info;

                memset(&info, 0, sizeof(info));
                info.rti_info[RTAX_DST] = sin6tosa(&mltaddr);
                info.rti_info[RTAX_GATEWAY] = sin6tosa(&ia->ia_addr);
                info.rti_info[RTAX_NETMASK] = sin6tosa(&mltmask);
                info.rti_info[RTAX_IFA] = sin6tosa(&ia->ia_addr);
                info.rti_flags = RTF_UP | RTF_CONNECTED;
                error = rtrequest1(RTM_ADD, &info, NULL);
                if (error)
                        goto out;
#undef  MLTMASK_LEN
        } else {
                rt_unref(rt);
        }
        imm = in6_joingroup(ifp, &mltaddr.sin6_addr, &error, 0);
        if (!imm) {
                nd6log(LOG_WARNING,
                    "addmulti failed for %s on %s (errno=%d)\n",
                    IN6_PRINT(ip6buf, &mltaddr.sin6_addr),
                    if_name(ifp), error);
                goto out;
        } else {
                mutex_enter(&in6_ifaddr_lock);
                LIST_INSERT_HEAD(&ia->ia6_memberships, imm, i6mm_chain);
                mutex_exit(&in6_ifaddr_lock);
        }
        return 0;

out:
        KASSERT(error != 0);
        return error;
}

/*
 * Update parameters of an IPv6 interface address.
 * If necessary, a new entry is created and linked into address chains.
 * This function is separated from in6_control().
 * XXX: should this be performed under splsoftnet()?
 */
static int
in6_update_ifa1(struct ifnet *ifp, struct in6_aliasreq *ifra,
    struct in6_ifaddr **iap, struct psref *psref, int flags)
{
        int error = 0, hostIsNew = 0, plen = -1;
        struct sockaddr_in6 dst6;
        struct in6_addrlifetime *lt;
        int dad_delay, was_tentative;
        struct in6_ifaddr *ia = iap ? *iap : NULL;
        char ip6buf[INET6_ADDRSTRLEN];
        bool addrmaskNotChanged = false;
        bool send_rtm_newaddr = (ip6_param_rt_msg == 1);
        int saved_flags = 0;

        KASSERT((iap == NULL && psref == NULL) ||
            (iap != NULL && psref != NULL));

        /* Validate parameters */
        if (ifp == NULL || ifra == NULL) /* this maybe redundant */
                return EINVAL;

        /*
         * The destination address for a p2p link must have a family
         * of AF_UNSPEC or AF_INET6.
         */
        if ((ifp->if_flags & IFF_POINTOPOINT) != 0 &&
            ifra->ifra_dstaddr.sin6_family != AF_INET6 &&
            ifra->ifra_dstaddr.sin6_family != AF_UNSPEC)
                return EAFNOSUPPORT;
        /*
         * validate ifra_prefixmask.  don't check sin6_family, netmask
         * does not carry fields other than sin6_len.
         */
        if (ifra->ifra_prefixmask.sin6_len > sizeof(struct sockaddr_in6))
                return EINVAL;
        /*
         * Because the IPv6 address architecture is classless, we require
         * users to specify a (non 0) prefix length (mask) for a new address.
         * We also require the prefix (when specified) mask is valid, and thus
         * reject a non-consecutive mask.
         */
        if (ia == NULL && ifra->ifra_prefixmask.sin6_len == 0)
                return EINVAL;
        if (ifra->ifra_prefixmask.sin6_len != 0) {
                plen = in6_mask2len(&ifra->ifra_prefixmask.sin6_addr,
                    (u_char *)&ifra->ifra_prefixmask +
                    ifra->ifra_prefixmask.sin6_len);
                if (plen <= 0)
                        return EINVAL;
        } else {
                /*
                 * In this case, ia must not be NULL.  We just use its prefix
                 * length.
                 */
                plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL);
        }
        /*
         * If the destination address on a p2p interface is specified,
         * and the address is a scoped one, validate/set the scope
         * zone identifier.
         */
        dst6 = ifra->ifra_dstaddr;
        if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) != 0 &&
            (dst6.sin6_family == AF_INET6)) {
                struct in6_addr in6_tmp;
                u_int32_t zoneid;

                in6_tmp = dst6.sin6_addr;
                if (in6_setscope(&in6_tmp, ifp, &zoneid))
                        return EINVAL; /* XXX: should be impossible */

                if (dst6.sin6_scope_id != 0) {
                        if (dst6.sin6_scope_id != zoneid)
                                return EINVAL;
                } else          /* user omit to specify the ID. */
                        dst6.sin6_scope_id = zoneid;

                /* convert into the internal form */
                if (sa6_embedscope(&dst6, 0))
                        return EINVAL; /* XXX: should be impossible */
        }
        /*
         * The destination address can be specified only for a p2p or a
         * loopback interface.  If specified, the corresponding prefix length
         * must be 128.
         */
        if (ifra->ifra_dstaddr.sin6_family == AF_INET6) {
#ifdef FORCE_P2PPLEN
                int i;
#endif

                if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) == 0) {
                        /* XXX: noisy message */
                        nd6log(LOG_INFO, "a destination can "
                            "be specified for a p2p or a loopback IF only\n");
                        return EINVAL;
                }
                if (plen != 128) {
                        nd6log(LOG_INFO, "prefixlen should "
                            "be 128 when dstaddr is specified\n");
#ifdef FORCE_P2PPLEN
                        /*
                         * To be compatible with old configurations,
                         * such as ifconfig gif0 inet6 2001::1 2001::2
                         * prefixlen 126, we override the specified
                         * prefixmask as if the prefix length was 128.
                         */
                        ifra->ifra_prefixmask.sin6_len =
                            sizeof(struct sockaddr_in6);
                        for (i = 0; i < 4; i++)
                                ifra->ifra_prefixmask.sin6_addr.s6_addr32[i] =
                                    0xffffffff;
                        plen = 128;
#else
                        return EINVAL;
#endif
                }
        }
        /* lifetime consistency check */
        lt = &ifra->ifra_lifetime;
        if (lt->ia6t_pltime > lt->ia6t_vltime)
                return EINVAL;
        if (lt->ia6t_vltime == 0) {
                /*
                 * the following log might be noisy, but this is a typical
                 * configuration mistake or a tool's bug.
                 */
                nd6log(LOG_INFO, "valid lifetime is 0 for %s\n",
                    IN6_PRINT(ip6buf, &ifra->ifra_addr.sin6_addr));

                if (ia == NULL)
                        return 0; /* there's nothing to do */
        }

#define sin6eq(a, b) \
        ((a)->sin6_len == sizeof(struct sockaddr_in6) && \
         (b)->sin6_len == sizeof(struct sockaddr_in6) && \
         IN6_ARE_ADDR_EQUAL(&(a)->sin6_addr, &(b)->sin6_addr))

        if (!send_rtm_newaddr) {
                if (ia != NULL &&
                    sin6eq(&ifra->ifra_addr, &ia->ia_addr) &&
                    sin6eq(&ifra->ifra_prefixmask, &ia->ia_prefixmask)) {
                        addrmaskNotChanged = true;
                        saved_flags = ia->ia6_flags;  /* check it later */
                }
        }
#undef sin6eq

        /*
         * 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 = malloc(sizeof(*ia), M_IFADDR, M_NOWAIT|M_ZERO);
                if (ia == NULL)
                        return ENOBUFS;
                LIST_INIT(&ia->ia6_memberships);
                /* Initialize the address and masks, and put time stamp */
                ia->ia_ifa.ifa_addr = sin6tosa(&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 = sin6tosa(&ia->ia_dstaddr);
                } else {
                        ia->ia_ifa.ifa_dstaddr = NULL;
                }
                ia->ia_ifa.ifa_netmask = sin6tosa(&ia->ia_prefixmask);

                ia->ia_ifp = ifp;
                IN6_ADDRLIST_ENTRY_INIT(ia);
                ifa_psref_init(&ia->ia_ifa);
        }

        /* update timestamp */
        ia->ia6_updatetime = time_uptime;

        /* set prefix mask */
        if (ifra->ifra_prefixmask.sin6_len) {
                if (ia->ia_prefixmask.sin6_len) {
                        if (!IN6_ARE_ADDR_EQUAL(&ia->ia_prefixmask.sin6_addr,
                            &ifra->ifra_prefixmask.sin6_addr))
                                in6_ifremprefix(ia);
                }
                ia->ia_prefixmask = ifra->ifra_prefixmask;
        }

        /* Set destination address. */
        if (dst6.sin6_family == AF_INET6) {
                if (!IN6_ARE_ADDR_EQUAL(&dst6.sin6_addr,
                    &ia->ia_dstaddr.sin6_addr))
                        in6_ifremprefix(ia);
                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;

        /*
         * configure address flags.
         * We need to preserve tentative state so DAD works if
         * something adds the same address before DAD finishes.
         */
        was_tentative = ia->ia6_flags & (IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED);
        ia->ia6_flags = ifra->ifra_flags;

        /*
         * 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 (ifp->if_link_state == LINK_STATE_DOWN) {
                ia->ia6_flags |= IN6_IFF_DETACHED;
                ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
        } else if ((hostIsNew || was_tentative) && if_do_dad(ifp) &&
                   ip6_dad_enabled()) {
                ia->ia6_flags |= IN6_IFF_TENTATIVE;
        }

        /*
         * 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;
        }

        if (!send_rtm_newaddr) {
                /*
                 * We will not send RTM_NEWADDR if the only difference between
                 * ia and ifra is preferred/valid lifetimes, because it is not
                 * very useful for userland programs to be notified of that
                 * changes.
                 */
                if (addrmaskNotChanged && ia->ia6_flags == saved_flags)
                        return 0;
        }

        if (hostIsNew) {
                /*
                 * We need a reference to ia before calling in6_ifinit.
                 * Otherwise ia can be freed in in6_ifinit accidentally.
                 */
                ifaref(&ia->ia_ifa);
        }

        /* Must execute in6_ifinit and ifa_insert atomically */
        mutex_enter(&in6_ifaddr_lock);

        /* reset the interface and routing table appropriately. */
        error = in6_ifinit(ifp, ia, &ifra->ifra_addr, hostIsNew);
        if (error != 0) {
                if (hostIsNew)
                        free(ia, M_IFADDR);
                mutex_exit(&in6_ifaddr_lock);
                return error;
        }

        /*
         * We are done if we have simply modified an existing address.
         */
        if (!hostIsNew) {
                mutex_exit(&in6_ifaddr_lock);
                return error;
        }

        /*
         * Insert ia to the global list and ifa to the interface's list.
         * A reference to it is already gained above.
         */
        IN6_ADDRLIST_WRITER_INSERT_TAIL(ia);
        ifa_insert(ifp, &ia->ia_ifa);

        mutex_exit(&in6_ifaddr_lock);

        /*
         * Beyond this point, we should call in6_purgeaddr upon an error,
         * not just go to unlink.
         */

        /* join necessary multicast groups */
        if ((ifp->if_flags & IFF_MULTICAST) != 0) {
                error = in6_join_mcastgroups(ifra, ia, ifp, flags);
                if (error != 0)
                        goto cleanup;
        }

        if (nd6_need_cache(ifp)) {
                /* XXX maybe unnecessary */
                ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
                ia->ia_ifa.ifa_flags |= RTF_CONNECTED;
        }

        /*
         * Perform DAD, if needed.
         * XXX It may be of use, if we can administratively
         * disable DAD.
         */
        if (hostIsNew && if_do_dad(ifp) &&
            ((ifra->ifra_flags & IN6_IFF_NODAD) == 0) &&
            (ia->ia6_flags & IN6_IFF_TENTATIVE))
        {
                int mindelay, maxdelay;

                dad_delay = 0;
                if ((flags & IN6_IFAUPDATE_DADDELAY)) {
                        struct in6_addr llsol;
                        struct in6_multi *in6m_sol = NULL;
                        /*
                         * We need to impose a delay before sending an NS
                         * for DAD.  Check if we also needed a delay for the
                         * corresponding MLD message.  If we did, the delay
                         * should be larger than the MLD delay (this could be
                         * relaxed a bit, but this simple logic is at least
                         * safe).
                         */
                        mindelay = 0;
                        error = in6_get_llsol_addr(&llsol, ifp,
                            &ifra->ifra_addr.sin6_addr);
                        in6_multi_lock(RW_READER);
                        if (error == 0)
                                in6m_sol = in6_lookup_multi(&llsol, ifp);
                        if (in6m_sol != NULL &&
                            in6m_sol->in6m_state == MLD_REPORTPENDING) {
                                mindelay = in6m_sol->in6m_timer;
                        }
                        in6_multi_unlock();
                        maxdelay = MAX_RTR_SOLICITATION_DELAY * hz;
                        if (maxdelay - mindelay == 0)
                                dad_delay = 0;
                        else {
                                dad_delay =
                                    (cprng_fast32() % (maxdelay - mindelay)) +
                                    mindelay;
                        }
                }
                /* +1 ensures callout is always used */
                nd6_dad_start(&ia->ia_ifa, dad_delay + 1);
        }

        if (iap != NULL) {
                *iap = ia;
                if (hostIsNew)
                        ia6_acquire(ia, psref);
        }

        return 0;

  cleanup:
        in6_purgeaddr(&ia->ia_ifa);
        return error;
}

int
in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra, int flags)
{
        int rc, s;

        s = splsoftnet();
        rc = in6_update_ifa1(ifp, ifra, NULL, NULL, flags);
        splx(s);
        return rc;
}

void
in6_purgeaddr(struct ifaddr *ifa)
{
        struct ifnet *ifp = ifa->ifa_ifp;
        struct in6_ifaddr *ia = (struct in6_ifaddr *) ifa;
        struct in6_multi_mship *imm;

        /* KASSERT(!ifa_held(ifa)); XXX need ifa_not_held (psref_not_held) */
        KASSERT(IFNET_LOCKED(ifp));

        ifa->ifa_flags |= IFA_DESTROYING;

        /* stop DAD processing */
        nd6_dad_stop(ifa);

        /* Delete any network route. */
        in6_ifremprefix(ia);

        /* Remove ownaddr's loopback rtentry, if it exists. */
        in6_ifremlocal(&(ia->ia_ifa));

        /*
         * leave from multicast groups we have joined for the interface
         */
    again:
        mutex_enter(&in6_ifaddr_lock);
        while ((imm = LIST_FIRST(&ia->ia6_memberships)) != NULL) {
                struct in6_multi *in6m __diagused = imm->i6mm_maddr;
                KASSERTMSG(in6m == NULL || in6m->in6m_ifp == ifp,
                    "in6m_ifp=%s ifp=%s", in6m ? in6m->in6m_ifp->if_xname : NULL,
                    ifp->if_xname);
                LIST_REMOVE(imm, i6mm_chain);
                mutex_exit(&in6_ifaddr_lock);

                in6_leavegroup(imm);
                goto again;
        }
        mutex_exit(&in6_ifaddr_lock);

        in6_unlink_ifa(ia, ifp);
}

static void
in6_unlink_ifa(struct in6_ifaddr *ia, struct ifnet *ifp)
{
        int     s = splsoftnet();

        mutex_enter(&in6_ifaddr_lock);
        IN6_ADDRLIST_WRITER_REMOVE(ia);
        ifa_remove(ifp, &ia->ia_ifa);
        /* Assume ifa_remove called pserialize_perform and psref_destroy */
        mutex_exit(&in6_ifaddr_lock);
        IN6_ADDRLIST_ENTRY_DESTROY(ia);

        /*
         * release another refcnt for the link from in6_ifaddr.
         * Note that we should decrement the refcnt at least once for all *BSD.
         */
        ifafree(&ia->ia_ifa);

        splx(s);
}

void
in6_purgeif(struct ifnet *ifp)
{

        IFNET_LOCK(ifp);
        in6_ifdetach(ifp);
        IFNET_UNLOCK(ifp);
}

void
in6_purge_mcast_references(struct in6_multi *in6m)
{
        struct  in6_ifaddr *ia;

        KASSERT(in6_multi_locked(RW_WRITER));

        mutex_enter(&in6_ifaddr_lock);
        IN6_ADDRLIST_WRITER_FOREACH(ia) {
                struct in6_multi_mship *imm;
                LIST_FOREACH(imm, &ia->ia6_memberships, i6mm_chain) {
                        if (imm->i6mm_maddr == in6m)
                                imm->i6mm_maddr = NULL;
                }
        }
        mutex_exit(&in6_ifaddr_lock);
}

/*
 * SIOC[GAD]LIFADDR.
 *      SIOCGLIFADDR: get first address. (?)
 *      SIOCGLIFADDR with IFLR_PREFIX:
 *              get first address that matches the specified prefix.
 *      SIOCALIFADDR: add the specified address.
 *      SIOCALIFADDR with IFLR_PREFIX:
 *              add the specified prefix, filling hostid part from
 *              the first link-local address.  prefixlen must be <= 64.
 *      SIOCDLIFADDR: delete the specified address.
 *      SIOCDLIFADDR with IFLR_PREFIX:
 *              delete the first address that matches the specified prefix.
 * return values:
 *      EINVAL on invalid parameters
 *      EADDRNOTAVAIL on prefix match failed/specified address not found
 *      other values may be returned from in6_ioctl()
 *
 * NOTE: SIOCALIFADDR(with IFLR_PREFIX set) allows prefixlen less than 64.
 * this is to accommodate address naming scheme other than RFC2374,
 * in the future.
 * RFC2373 defines interface id to be 64bit, but it allows non-RFC2374
 * address encoding scheme. (see figure on page 8)
 */
static int
in6_lifaddr_ioctl(struct socket *so, u_long cmd, void *data, 
        struct ifnet *ifp)
{
        struct in6_ifaddr *ia = NULL; /* XXX gcc 4.8 maybe-uninitialized */
        struct if_laddrreq *iflr = (struct if_laddrreq *)data;
        struct ifaddr *ifa;
        struct sockaddr *sa;

        /* sanity checks */
        if (!data || !ifp) {
                panic("invalid argument to in6_lifaddr_ioctl");
                /* NOTREACHED */
        }

        switch (cmd) {
        case SIOCGLIFADDR:
                /* address must be specified on GET with IFLR_PREFIX */
                if ((iflr->flags & IFLR_PREFIX) == 0)
                        break;
                /* FALLTHROUGH */
        case SIOCALIFADDR:
        case SIOCDLIFADDR:
                /* address must be specified on ADD and DELETE */
                sa = (struct sockaddr *)&iflr->addr;
                if (sa->sa_family != AF_INET6)
                        return EINVAL;
                if (sa->sa_len != sizeof(struct sockaddr_in6))
                        return EINVAL;
                /* XXX need improvement */
                sa = (struct sockaddr *)&iflr->dstaddr;
                if (sa->sa_family && sa->sa_family != AF_INET6)
                        return EINVAL;
                if (sa->sa_len && sa->sa_len != sizeof(struct sockaddr_in6))
                        return EINVAL;
                break;
        default: /* shouldn't happen */
#if 0
                panic("invalid cmd to in6_lifaddr_ioctl");
                /* NOTREACHED */
#else
                return EOPNOTSUPP;
#endif
        }
        if (sizeof(struct in6_addr) * NBBY < iflr->prefixlen)
                return EINVAL;

        switch (cmd) {
        case SIOCALIFADDR:
            {
                struct in6_aliasreq ifra;
                struct in6_addr *xhostid = NULL;
                int prefixlen;
                int bound = curlwp_bind();
                struct psref psref;

                if ((iflr->flags & IFLR_PREFIX) != 0) {
                        struct sockaddr_in6 *sin6;

                        /*
                         * xhostid is to fill in the hostid part of the
                         * address.  xhostid points to the first link-local
                         * address attached to the interface.
                         */
                        ia = in6ifa_ifpforlinklocal_psref(ifp, 0, &psref);
                        if (ia == NULL) {
                                curlwp_bindx(bound);
                                return EADDRNOTAVAIL;
                        }
                        xhostid = IFA_IN6(&ia->ia_ifa);

                        /* prefixlen must be <= 64. */
                        if (64 < iflr->prefixlen) {
                                ia6_release(ia, &psref);
                                curlwp_bindx(bound);
                                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) {
                                ia6_release(ia, &psref);
                                curlwp_bindx(bound);
                                return EINVAL;
                        }
                } else
                        prefixlen = iflr->prefixlen;

                /* copy args to in6_aliasreq, perform ioctl(SIOCAIFADDR_IN6). */
                memset(&ifra, 0, sizeof(ifra));
                memcpy(ifra.ifra_name, iflr->iflr_name, sizeof(ifra.ifra_name));

                memcpy(&ifra.ifra_addr, &iflr->addr,
                    ((struct sockaddr *)&iflr->addr)->sa_len);
                if (xhostid) {
                        /* fill in hostid part */
                        ifra.ifra_addr.sin6_addr.s6_addr32[2] =
                            xhostid->s6_addr32[2];
                        ifra.ifra_addr.sin6_addr.s6_addr32[3] =
                            xhostid->s6_addr32[3];
                }

                if (((struct sockaddr *)&iflr->dstaddr)->sa_family) { /* XXX */
                        memcpy(&ifra.ifra_dstaddr, &iflr->dstaddr,
                            ((struct sockaddr *)&iflr->dstaddr)->sa_len);
                        if (xhostid) {
                                ifra.ifra_dstaddr.sin6_addr.s6_addr32[2] =
                                    xhostid->s6_addr32[2];
                                ifra.ifra_dstaddr.sin6_addr.s6_addr32[3] =
                                    xhostid->s6_addr32[3];
                        }
                }
                if (xhostid) {
                        ia6_release(ia, &psref);
                        ia = NULL;
                }
                curlwp_bindx(bound);

                ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
                in6_prefixlen2mask(&ifra.ifra_prefixmask.sin6_addr, prefixlen);

                ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
                ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
                ifra.ifra_flags = iflr->flags & ~IFLR_PREFIX;
                return in6_control(so, SIOCAIFADDR_IN6, &ifra, ifp);
            }
        case SIOCGLIFADDR:
        case SIOCDLIFADDR:
            {
                struct in6_addr mask, candidate, match;
                struct sockaddr_in6 *sin6;
                int cmp;
                int error, s;

                memset(&mask, 0, sizeof(mask));
                if (iflr->flags & IFLR_PREFIX) {
                        /* lookup a prefix rather than address. */
                        in6_prefixlen2mask(&mask, iflr->prefixlen);

                        sin6 = (struct sockaddr_in6 *)&iflr->addr;
                        memcpy(&match, &sin6->sin6_addr, 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 (memcmp(&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;
                                memcpy(&match, &sin6->sin6_addr, sizeof(match));

                                cmp = 1;
                        }
                }

                s = pserialize_read_enter();
                IFADDR_READER_FOREACH(ifa, ifp) {
                        if (ifa->ifa_addr->sa_family != AF_INET6)
                                continue;
                        if (!cmp)
                                break;

                        /*
                         * XXX: this is adhoc, but is necessary to allow
                         * a user to specify fe80::/64 (not /10) for a
                         * link-local address.
                         */
                        memcpy(&candidate, IFA_IN6(ifa), 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) {
                        error = EADDRNOTAVAIL;
                        goto error;
                }
                ia = ifa2ia6(ifa);

                if (cmd == SIOCGLIFADDR) {
                        /* fill in the if_laddrreq structure */
                        memcpy(&iflr->addr, &ia->ia_addr, ia->ia_addr.sin6_len);
                        error = sa6_recoverscope(
                            (struct sockaddr_in6 *)&iflr->addr);
                        if (error != 0)
                                goto error;

                        if ((ifp->if_flags & IFF_POINTOPOINT) != 0) {
                                memcpy(&iflr->dstaddr, &ia->ia_dstaddr,
                                    ia->ia_dstaddr.sin6_len);
                                error = sa6_recoverscope(
                                    (struct sockaddr_in6 *)&iflr->dstaddr);
                                if (error != 0)
                                        goto error;
                        } else
                                memset(&iflr->dstaddr, 0, sizeof(iflr->dstaddr));

                        iflr->prefixlen =
                            in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL);

                        iflr->flags = ia->ia6_flags;    /* XXX */

                        error = 0;
                } else {
                        struct in6_aliasreq ifra;

                        /* fill in6_aliasreq and do ioctl(SIOCDIFADDR_IN6) */
                        memset(&ifra, 0, sizeof(ifra));
                        memcpy(ifra.ifra_name, iflr->iflr_name,
                            sizeof(ifra.ifra_name));

                        memcpy(&ifra.ifra_addr, &ia->ia_addr,
                            ia->ia_addr.sin6_len);
                        if ((ifp->if_flags & IFF_POINTOPOINT) != 0) {
                                memcpy(&ifra.ifra_dstaddr, &ia->ia_dstaddr,
                                    ia->ia_dstaddr.sin6_len);
                        } else {
                                memset(&ifra.ifra_dstaddr, 0,
                                    sizeof(ifra.ifra_dstaddr));
                        }
                        memcpy(&ifra.ifra_dstaddr, &ia->ia_prefixmask,
                            ia->ia_prefixmask.sin6_len);

                        ifra.ifra_flags = ia->ia6_flags;
                        pserialize_read_exit(s);

                        return in6_control(so, SIOCDIFADDR_IN6, &ifra, ifp);
                }
        error:
                pserialize_read_exit(s);
                return error;
            }
        }

        return EOPNOTSUPP;      /* just for safety */
}

/*
 * Initialize an interface's internet6 address
 * and routing table entry.
 */
static int
in6_ifinit(struct ifnet *ifp, struct in6_ifaddr *ia, 
        const struct sockaddr_in6 *sin6, int newhost)
{
        int     error = 0, ifacount = 0;
        int s;
        struct ifaddr *ifa;

        KASSERT(mutex_owned(&in6_ifaddr_lock));

        /*
         * Give the interface a chance to initialize
         * if this is its first address,
         * and to validate the address if necessary.
         */
        s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ifacount++;
        }
        pserialize_read_exit(s);

        ia->ia_addr = *sin6;

        if (ifacount == 0 &&
            (error = if_addr_init(ifp, &ia->ia_ifa, true)) != 0) {
                return error;
        }

        ia->ia_ifa.ifa_metric = ifp->if_metric;

        /* we could do in(6)_socktrim here, but just omit it at this moment. */

        /* Add ownaddr as loopback rtentry, if necessary (ex. on p2p link). */
        if (newhost) {
                /* set the rtrequest function to create llinfo */
                if (ifp->if_flags & IFF_POINTOPOINT)
                        ia->ia_ifa.ifa_rtrequest = p2p_rtrequest;
                else if ((ifp->if_flags & IFF_LOOPBACK) == 0)
                        ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
                in6_ifaddlocal(&ia->ia_ifa);
        } else {
                /* Inform the routing socket of new flags/timings */
                rt_addrmsg(RTM_NEWADDR, &ia->ia_ifa);
        }

        /* Add the network prefix route. */
        if ((error = in6_ifaddprefix(ia)) != 0) {
                if (newhost)
                        in6_ifremlocal(&ia->ia_ifa);
                return error;
        }

        return error;
}

static struct ifaddr *
bestifa(struct ifaddr *best_ifa, struct ifaddr *ifa)
{
        if (best_ifa == NULL || best_ifa->ifa_preference < ifa->ifa_preference)
                return ifa;
        return best_ifa;
}

/*
 * Find an IPv6 interface link-local address specific to an interface.
 */
struct in6_ifaddr *
in6ifa_ifpforlinklocal(const struct ifnet *ifp, const int ignoreflags)
{
        struct ifaddr *best_ifa = NULL, *ifa;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                if (!IN6_IS_ADDR_LINKLOCAL(IFA_IN6(ifa)))
                        continue;
                if ((((struct in6_ifaddr *)ifa)->ia6_flags & ignoreflags) != 0)
                        continue;
                best_ifa = bestifa(best_ifa, ifa);
        }

        return (struct in6_ifaddr *)best_ifa;
}

struct in6_ifaddr *
in6ifa_ifpforlinklocal_psref(const struct ifnet *ifp, const int ignoreflags,
    struct psref *psref)
{
        struct in6_ifaddr *ia;
        int s = pserialize_read_enter();

        ia = in6ifa_ifpforlinklocal(ifp, ignoreflags);
        if (ia != NULL)
                ia6_acquire(ia, psref);
        pserialize_read_exit(s);

        return ia;
}

/*
 * find the internet address corresponding to a given address.
 * ifaddr is returned referenced.
 */
struct in6_ifaddr *
in6ifa_ifwithaddr(const struct in6_addr *addr, uint32_t zoneid)
{
        struct in6_ifaddr *ia;
        int s;

        s = pserialize_read_enter();
        IN6_ADDRLIST_READER_FOREACH(ia) {
                if (IN6_ARE_ADDR_EQUAL(IA6_IN6(ia), addr)) {
                        if (zoneid != 0 &&
                            zoneid != ia->ia_addr.sin6_scope_id)
                                continue;
                        ifaref(&ia->ia_ifa);
                        break;
                }
        }
        pserialize_read_exit(s);

        return ia;
}

/*
 * find the internet address corresponding to a given interface and address.
 */
struct in6_ifaddr *
in6ifa_ifpwithaddr(const struct ifnet *ifp, const struct in6_addr *addr)
{
        struct ifaddr *best_ifa = NULL, *ifa;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                if (!IN6_ARE_ADDR_EQUAL(addr, IFA_IN6(ifa)))
                        continue;
                best_ifa = bestifa(best_ifa, ifa);
        }

        return (struct in6_ifaddr *)best_ifa;
}

struct in6_ifaddr *
in6ifa_ifpwithaddr_psref(const struct ifnet *ifp, const struct in6_addr *addr,
    struct psref *psref)
{
        struct in6_ifaddr *ia;
        int s = pserialize_read_enter();

        ia = in6ifa_ifpwithaddr(ifp, addr);
        if (ia != NULL)
                ia6_acquire(ia, psref);
        pserialize_read_exit(s);

        return ia;
}

static struct in6_ifaddr *
bestia(struct in6_ifaddr *best_ia, struct in6_ifaddr *ia)
{
        if (best_ia == NULL ||
            best_ia->ia_ifa.ifa_preference < ia->ia_ifa.ifa_preference)
                return ia;
        return best_ia;
}

struct ifaddr *
in6ifa_first_lladdr(const struct ifnet *ifp)
{
        struct ifaddr *ifa;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family == AF_INET6) {
                        struct sockaddr_in6 *sin6 = satosin6(ifa->ifa_addr);
                        if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr))
                                break;
                }
        }

        return ifa;
}

struct ifaddr *
in6ifa_first_lladdr_psref(const struct ifnet *ifp, struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = in6ifa_first_lladdr(ifp);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * Determine if an address is on a local network.
 */
int
in6_localaddr(const struct in6_addr *in6)
{
        struct in6_ifaddr *ia;
        int s;

        if (IN6_IS_ADDR_LOOPBACK(in6) || IN6_IS_ADDR_LINKLOCAL(in6))
                return 1;

        s = pserialize_read_enter();
        IN6_ADDRLIST_READER_FOREACH(ia) {
                if (IN6_ARE_MASKED_ADDR_EQUAL(in6, &ia->ia_addr.sin6_addr,
                                              &ia->ia_prefixmask.sin6_addr)) {
                        pserialize_read_exit(s);
                        return 1;
                }
        }
        pserialize_read_exit(s);

        return 0;
}

int
in6_is_addr_deprecated(struct sockaddr_in6 *sa6)
{
        struct in6_ifaddr *ia;
        int s;

        s = pserialize_read_enter();
        IN6_ADDRLIST_READER_FOREACH(ia) {
                if (IN6_ARE_ADDR_EQUAL(&ia->ia_addr.sin6_addr,
                    &sa6->sin6_addr) &&
#ifdef SCOPEDROUTING
                    ia->ia_addr.sin6_scope_id == sa6->sin6_scope_id &&
#endif
                    (ia->ia6_flags & IN6_IFF_DEPRECATED) != 0) {
                        pserialize_read_exit(s);
                        return 1; /* true */
                }

                /* XXX: do we still have to go thru the rest of the list? */
        }
        pserialize_read_exit(s);

        return 0;               /* false */
}

/*
 * return length of part which dst and src are equal
 * hard coding...
 */
int
in6_matchlen(struct in6_addr *src, struct in6_addr *dst)
{
        int match = 0;
        u_char *s = (u_char *)src, *d = (u_char *)dst;
        u_char *lim = s + 16, r;

        while (s < lim)
                if ((r = (*d++ ^ *s++)) != 0) {
                        while (r < 128) {
                                match++;
                                r <<= 1;
                        }
                        break;
                } else
                        match += NBBY;
        return match;
}

void
in6_prefixlen2mask(struct in6_addr *maskp, int len)
{
        static const u_char maskarray[NBBY] = {0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};
        int bytelen, bitlen, i;

        /* sanity check */
        if (len < 0 || len > 128) {
                log(LOG_ERR, "in6_prefixlen2mask: invalid prefix length(%d)\n",
                    len);
                return;
        }

        memset(maskp, 0, sizeof(*maskp));
        bytelen = len / NBBY;
        bitlen = len % NBBY;
        for (i = 0; i < bytelen; i++)
                maskp->s6_addr[i] = 0xff;
        if (bitlen)
                maskp->s6_addr[bytelen] = maskarray[bitlen - 1];
}

/*
 * return the best address out of the same scope. if no address was
 * found, return the first valid address from designated IF.
 */
struct in6_ifaddr *
in6_ifawithifp(struct ifnet *ifp, struct in6_addr *dst)
{
        int dst_scope = in6_addrscope(dst), blen = -1, tlen;
        struct ifaddr *ifa;
        struct in6_ifaddr *best_ia = NULL, *ia;
        struct in6_ifaddr *dep[2];      /* last-resort: deprecated */

        dep[0] = dep[1] = NULL;

        /*
         * We first look for addresses in the same scope.
         * If there is one, return it.
         * If two or more, return one which matches the dst longest.
         * If none, return one of global addresses assigned other ifs.
         */
        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ia = (struct in6_ifaddr *)ifa;
                if (ia->ia6_flags & IN6_IFF_ANYCAST)
                        continue; /* XXX: is there any case to allow anycast? */
                if (ia->ia6_flags & IN6_IFF_NOTREADY)
                        continue; /* don't use this interface */
                if (ia->ia6_flags & IN6_IFF_DETACHED)
                        continue;
                if (ia->ia6_flags & IN6_IFF_DEPRECATED) {
                        if (ip6_use_deprecated)
                                dep[0] = ia;
                        continue;
                }

                if (dst_scope != in6_addrscope(IFA_IN6(ifa)))
                        continue;
                /*
                 * call in6_matchlen() as few as possible
                 */
                if (best_ia == NULL) {
                        best_ia = ia;
                        continue;
                }
                if (blen == -1)
                        blen = in6_matchlen(&best_ia->ia_addr.sin6_addr, dst);
                tlen = in6_matchlen(IFA_IN6(ifa), dst);
                if (tlen > blen) {
                        blen = tlen;
                        best_ia = ia;
                } else if (tlen == blen)
                        best_ia = bestia(best_ia, ia);
        }
        if (best_ia != NULL)
                return best_ia;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ia = (struct in6_ifaddr *)ifa;
                if (ia->ia6_flags & IN6_IFF_ANYCAST)
                        continue; /* XXX: is there any case to allow anycast? */
                if (ia->ia6_flags & IN6_IFF_NOTREADY)
                        continue; /* don't use this interface */
                if (ia->ia6_flags & IN6_IFF_DETACHED)
                        continue;
                if (ia->ia6_flags & IN6_IFF_DEPRECATED) {
                        if (ip6_use_deprecated)
                                dep[1] = (struct in6_ifaddr *)ifa;
                        continue;
                }

                best_ia = bestia(best_ia, ia);
        }
        if (best_ia != NULL)
                return best_ia;

        /* use the last-resort values, that are, deprecated addresses */
        if (dep[0])
                return dep[0];
        if (dep[1])
                return dep[1];

        return NULL;
}

/*
 * perform DAD when interface becomes IFF_UP.
 */
void
in6_if_link_up(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        struct in6_ifaddr *ia;
        int s, bound;
        char ip6buf[INET6_ADDRSTRLEN];

        /* Ensure it's sane to run DAD */
        if (ifp->if_link_state == LINK_STATE_DOWN)
                return;
        if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
                return;

        bound = curlwp_bind();
        s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                struct psref psref;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                ifa_acquire(ifa, &psref);
                pserialize_read_exit(s);
                ia = (struct in6_ifaddr *)ifa;

                /* If detached then mark as tentative */
                if (ia->ia6_flags & IN6_IFF_DETACHED) {
                        ia->ia6_flags &= ~IN6_IFF_DETACHED;
                        if (ip6_dad_enabled() && if_do_dad(ifp)) {
                                ia->ia6_flags |= IN6_IFF_TENTATIVE;
                                nd6log(LOG_ERR, "%s marked tentative\n",
                                    IN6_PRINT(ip6buf,
                                    &ia->ia_addr.sin6_addr));
                        } else if ((ia->ia6_flags & IN6_IFF_TENTATIVE) == 0)
                                rt_addrmsg(RTM_NEWADDR, ifa);
                }

                if (ia->ia6_flags & IN6_IFF_TENTATIVE) {
                        int rand_delay;

                        /* Clear the duplicated flag as we're starting DAD. */
                        ia->ia6_flags &= ~IN6_IFF_DUPLICATED;

                        /*
                         * 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.
                         */
                        rand_delay = cprng_fast32() %
                            (MAX_RTR_SOLICITATION_DELAY * hz);
                        /* +1 ensures callout is always used */
                        nd6_dad_start(ifa, rand_delay + 1);
                }

                s = pserialize_read_enter();
                ifa_release(ifa, &psref);
        }
        pserialize_read_exit(s);
        curlwp_bindx(bound);
}

void
in6_if_up(struct ifnet *ifp)
{

        /*
         * special cases, like 6to4, are handled in in6_ifattach
         */
        in6_ifattach(ifp, NULL);

        /* interface may not support link state, so bring it up also */
        in6_if_link_up(ifp);
}

/*
 * Mark all addresses as detached.
 */
void
in6_if_link_down(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        struct in6_ifaddr *ia;
        int s, bound;
        char ip6buf[INET6_ADDRSTRLEN];

        bound = curlwp_bind();
        s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                struct psref psref;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                ifa_acquire(ifa, &psref);
                pserialize_read_exit(s);
                ia = (struct in6_ifaddr *)ifa;

                /* Stop DAD processing */
                nd6_dad_stop(ifa);

                /*
                 * Mark the address as detached.
                 * This satisfies RFC4862 Section 5.3, but we should apply
                 * this logic to all addresses to be a good citizen and
                 * avoid potential duplicated addresses.
                 * When the interface comes up again, detached addresses
                 * are marked tentative and DAD commences.
                 */
                if (!(ia->ia6_flags & IN6_IFF_DETACHED)) {
                        nd6log(LOG_DEBUG, "%s marked detached\n",
                            IN6_PRINT(ip6buf, &ia->ia_addr.sin6_addr));
                        ia->ia6_flags |= IN6_IFF_DETACHED;
                        ia->ia6_flags &=
                            ~(IN6_IFF_TENTATIVE | IN6_IFF_DUPLICATED);
                        rt_addrmsg(RTM_NEWADDR, ifa);
                }

                s = pserialize_read_enter();
                ifa_release(ifa, &psref);
        }
        pserialize_read_exit(s);
        curlwp_bindx(bound);

        /* Clear ND6_IFF_IFDISABLED to allow DAD again on link-up. */
        if (ifp->if_afdata[AF_INET6] != NULL)
                ND_IFINFO(ifp)->flags &= ~ND6_IFF_IFDISABLED;
}

void
in6_if_down(struct ifnet *ifp)
{

        in6_if_link_down(ifp);
        lltable_purge_entries(LLTABLE6(ifp));
}

void
in6_if_link_state_change(struct ifnet *ifp, int link_state)
{

        /*
         * Treat LINK_STATE_UNKNOWN as UP.
         * LINK_STATE_UNKNOWN transitions to LINK_STATE_DOWN when
         * if_link_state_change() transitions to LINK_STATE_UP.
         */
        if (link_state == LINK_STATE_DOWN)
                in6_if_link_down(ifp);
        else
                in6_if_link_up(ifp);
}

int
in6_tunnel_validate(const struct ip6_hdr *ip6, const struct in6_addr *src,
    const struct in6_addr *dst)
{

        /* check for address match */
        if (!IN6_ARE_ADDR_EQUAL(src, &ip6->ip6_dst) ||
            !IN6_ARE_ADDR_EQUAL(dst, &ip6->ip6_src))
                return 0;

        /* martian filters on outer source - done in ip6_input */

        /* NOTE: the packet may be dropped by uRPF. */

        /* return valid bytes length */
        return sizeof(*src) + sizeof(*dst);
}

#define IN6_LLTBL_DEFAULT_HSIZE 32
#define IN6_LLTBL_HASH(k, h) \
        (((((((k >> 8) ^ k) >> 8) ^ k) >> 8) ^ k) & ((h) - 1))

/*
 * Do actual deallocation of @lle.
 * Called by LLE_FREE_LOCKED when number of references
 * drops to zero.
 */
static void
in6_lltable_destroy_lle(struct llentry *lle)
{

        KASSERTMSG(lle->la_numheld == 0, "la_numheld=%d", lle->la_numheld);

        LLE_WUNLOCK(lle);
        LLE_LOCK_DESTROY(lle);
        llentry_pool_put(lle);
}

static struct llentry *
in6_lltable_new(const struct in6_addr *addr6, u_int flags)
{
        struct llentry *lle;

        lle = llentry_pool_get(PR_NOWAIT);
        if (lle == NULL)                /* NB: caller generates msg */
                return NULL;

        lle->r_l3addr.addr6 = *addr6;
        lle->lle_refcnt = 1;
        lle->lle_free = in6_lltable_destroy_lle;
        LLE_LOCK_INIT(lle);
        callout_init(&lle->lle_timer, CALLOUT_MPSAFE);

        return lle;
}

static int
in6_lltable_match_prefix(const struct sockaddr *prefix,
    const struct sockaddr *mask, u_int flags, struct llentry *lle)
{
        const struct sockaddr_in6 *pfx = (const struct sockaddr_in6 *)prefix;
        const struct sockaddr_in6 *msk = (const struct sockaddr_in6 *)mask;

        if (IN6_ARE_MASKED_ADDR_EQUAL(&lle->r_l3addr.addr6,
            &pfx->sin6_addr, &msk->sin6_addr) &&
            ((flags & LLE_STATIC) || !(lle->la_flags & LLE_STATIC)))
                return 1;

        return 0;
}

static void
in6_lltable_free_entry(struct lltable *llt, struct llentry *lle)
{

        LLE_WLOCK_ASSERT(lle);
        (void) llentry_free(lle);
}

static int
in6_lltable_rtcheck(struct ifnet *ifp, u_int flags,
    const struct sockaddr *l3addr, const struct rtentry *rt)
{
        char ip6buf[INET6_ADDRSTRLEN];

        if (rt == NULL || (rt->rt_flags & RTF_GATEWAY) || rt->rt_ifp != ifp) {
                int s;
                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 */
                s = pserialize_read_enter();
                ifa = ifaof_ifpforaddr(l3addr, ifp);
                if (ifa != NULL) {
                        pserialize_read_exit(s);
                        return 0;
                }
                pserialize_read_exit(s);
                log(LOG_INFO, "IPv6 address: \"%s\" is not on the network\n",
                    IN6_PRINT(ip6buf,
                    &((const struct sockaddr_in6 *)l3addr)->sin6_addr));
                return EINVAL;
        }
        return 0;
}

static inline uint32_t
in6_lltable_hash_dst(const struct in6_addr *dst, uint32_t hsize)
{

        return IN6_LLTBL_HASH(dst->s6_addr32[3], hsize);
}

static uint32_t
in6_lltable_hash(const struct llentry *lle, uint32_t hsize)
{

        return in6_lltable_hash_dst(&lle->r_l3addr.addr6, hsize);
}

static void
in6_lltable_fill_sa_entry(const struct llentry *lle, struct sockaddr *sa)
{
        struct sockaddr_in6 *sin6;

        sin6 = (struct sockaddr_in6 *)sa;
        bzero(sin6, sizeof(*sin6));
        sin6->sin6_family = AF_INET6;
        sin6->sin6_len = sizeof(*sin6);
        sin6->sin6_addr = lle->r_l3addr.addr6;
}

static inline struct llentry *
in6_lltable_find_dst(struct lltable *llt, const struct in6_addr *dst)
{
        struct llentry *lle;
        struct llentries *lleh;
        u_int hashidx;

        hashidx = in6_lltable_hash_dst(dst, llt->llt_hsize);
        lleh = &llt->lle_head[hashidx];
        LIST_FOREACH(lle, lleh, lle_next) {
                if (lle->la_flags & LLE_DELETED)
                        continue;
                if (IN6_ARE_ADDR_EQUAL(&lle->r_l3addr.addr6, dst))
                        break;
        }

        return lle;
}

static int
in6_lltable_delete(struct lltable *llt, u_int flags,
        const struct sockaddr *l3addr)
{
        const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr;
        struct llentry *lle;

        IF_AFDATA_WLOCK_ASSERT(llt->llt_ifp);
        KASSERTMSG(l3addr->sa_family == AF_INET6,
            "sin_family %d", l3addr->sa_family);

        lle = in6_lltable_find_dst(llt, &sin6->sin6_addr);

        if (lle == NULL) {
#ifdef LLTABLE_DEBUG
                char buf[64];
                sockaddr_format(l3addr, buf, sizeof(buf));
                log(LOG_INFO, "%s: cache for %s is not found\n",
                    __func__, buf);
#endif
                return ENOENT;
        }

        LLE_WLOCK(lle);
#ifdef LLTABLE_DEBUG
        {
                char buf[64];
                sockaddr_format(l3addr, buf, sizeof(buf));
                log(LOG_INFO, "%s: cache for %s (%p) is deleted\n",
                    __func__, buf, lle);
        }
#endif
        llentry_free(lle);

        return 0;
}

static struct llentry *
in6_lltable_create(struct lltable *llt, u_int flags,
    const struct sockaddr *l3addr, const struct rtentry *rt)
{
        const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr;
        struct ifnet *ifp = llt->llt_ifp;
        struct llentry *lle;

        IF_AFDATA_WLOCK_ASSERT(ifp);
        KASSERTMSG(l3addr->sa_family == AF_INET6,
            "sin_family %d", l3addr->sa_family);

        lle = in6_lltable_find_dst(llt, &sin6->sin6_addr);

        if (lle != NULL) {
                LLE_WLOCK(lle);
                return lle;
        }

        /*
         * 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, rt) != 0)
                return NULL;

        lle = in6_lltable_new(&sin6->sin6_addr, flags);
        if (lle == NULL) {
                log(LOG_INFO, "lla_lookup: new lle malloc failed\n");
                return NULL;
        }
        lle->la_flags = flags;
        if ((flags & LLE_IFADDR) == LLE_IFADDR) {
                memcpy(&lle->ll_addr, CLLADDR(ifp->if_sadl), ifp->if_addrlen);
                lle->la_flags |= LLE_VALID;
        }

        lltable_link_entry(llt, lle);
        LLE_WLOCK(lle);

        return lle;
}

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 llentry *lle;

        IF_AFDATA_LOCK_ASSERT(llt->llt_ifp);
        KASSERTMSG(l3addr->sa_family == AF_INET6,
            "sin_family %d", l3addr->sa_family);

        lle = in6_lltable_find_dst(llt, &sin6->sin6_addr);

        if (lle == NULL)
                return NULL;

        if (flags & LLE_EXCLUSIVE)
                LLE_WLOCK(lle);
        else
                LLE_RLOCK(lle);
        return lle;
}

static int
in6_lltable_dump_entry(struct lltable *llt, struct llentry *lle,
    struct rt_walkarg *w)
{
        struct sockaddr_in6 sin6;

        LLTABLE_LOCK_ASSERT();

        /* skip deleted entries */
        if (lle->la_flags & LLE_DELETED)
                return 0;

        sockaddr_in6_init(&sin6, &lle->r_l3addr.addr6, 0, 0, 0);

        return lltable_dump_entry(llt, lle, w, sin6tosa(&sin6));
}

static struct lltable *
in6_lltattach(struct ifnet *ifp)
{
        struct lltable *llt;

        llt = lltable_allocate_htbl(IN6_LLTBL_DEFAULT_HSIZE);
        llt->llt_af = AF_INET6;
        llt->llt_ifp = ifp;

        llt->llt_lookup = in6_lltable_lookup;
        llt->llt_create = in6_lltable_create;
        llt->llt_delete = in6_lltable_delete;
        llt->llt_dump_entry = in6_lltable_dump_entry;
        llt->llt_hash = in6_lltable_hash;
        llt->llt_fill_sa_entry = in6_lltable_fill_sa_entry;
        llt->llt_free_entry = in6_lltable_free_entry;
        llt->llt_match_prefix = in6_lltable_match_prefix;
        lltable_link(llt);

        return llt;
}

void *
in6_domifattach(struct ifnet *ifp)
{
        struct in6_ifextra *ext;

        ext = malloc(sizeof(*ext), M_IFADDR, M_WAITOK|M_ZERO);

        ext->in6_ifstat = malloc(sizeof(struct in6_ifstat),
            M_IFADDR, M_WAITOK|M_ZERO);

        ext->icmp6_ifstat = malloc(sizeof(struct icmp6_ifstat),
            M_IFADDR, M_WAITOK|M_ZERO);

        ext->nd_ifinfo = nd6_ifattach(ifp);
        ext->scope6_id = scope6_ifattach(ifp);
        ext->lltable = in6_lltattach(ifp);

        return ext;
}

void
in6_domifdetach(struct ifnet *ifp, void *aux)
{
        struct in6_ifextra *ext = (struct in6_ifextra *)aux;

        lltable_free(ext->lltable);
        ext->lltable = NULL;
        SOFTNET_LOCK_UNLESS_NET_MPSAFE();
        nd6_ifdetach(ifp, ext);
        SOFTNET_UNLOCK_UNLESS_NET_MPSAFE();
        free(ext->in6_ifstat, M_IFADDR);
        free(ext->icmp6_ifstat, M_IFADDR);
        scope6_ifdetach(ext->scope6_id);
        free(ext, M_IFADDR);
}

/*
 * Convert IPv4 address stored in struct in_addr to IPv4-Mapped IPv6 address
 * stored in struct in6_addr as defined in RFC 4921 section 2.5.5.2.
 */
void
in6_in_2_v4mapin6(const struct in_addr *in, struct in6_addr *in6)
{
        in6->s6_addr32[0] = 0;
        in6->s6_addr32[1] = 0;
        in6->s6_addr32[2] = IPV6_ADDR_INT32_SMP;
        in6->s6_addr32[3] = in->s_addr;
}

/*
 * 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)
{
        memset(sin, 0, 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(const struct sockaddr_in *sin, struct sockaddr_in6 *sin6)
{
        memset(sin6, 0, sizeof(*sin6));
        sin6->sin6_len = sizeof(struct sockaddr_in6);
        sin6->sin6_family = AF_INET6;
        sin6->sin6_port = sin->sin_port;
        in6_in_2_v4mapin6(&sin->sin_addr, &sin6->sin6_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 = sin6tosa(sin6_p);
}