Add the management part of address selection policy described in RFC

[dragonfly.git] / sys / netinet6 / in6.c

/*      $FreeBSD: src/sys/netinet6/in6.c,v 1.7.2.9 2002/04/28 05:40:26 suz Exp $        */
/*      $DragonFly: src/sys/netinet6/in6.c,v 1.30 2008/10/03 07:59:20 hasso Exp $       */
/*      $KAME: in6.c,v 1.259 2002/01/21 11:37:50 keiichi Exp $  */

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

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

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sockio.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/thread2.h>

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

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/mld6_var.h>
#include <netinet6/ip6_mroute.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/scope6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/in6_var.h>

#include <net/net_osdep.h>

/*
 * Definitions of some costant IP6 addresses.
 */
const struct in6_addr kin6addr_any = IN6ADDR_ANY_INIT;
const struct in6_addr kin6addr_loopback = IN6ADDR_LOOPBACK_INIT;
const struct in6_addr kin6addr_nodelocal_allnodes =
        IN6ADDR_NODELOCAL_ALLNODES_INIT;
const struct in6_addr kin6addr_linklocal_allnodes =
        IN6ADDR_LINKLOCAL_ALLNODES_INIT;
const struct in6_addr kin6addr_linklocal_allrouters =
        IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;

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

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

static int in6_lifaddr_ioctl (struct socket *, u_long, caddr_t,
        struct ifnet *, struct thread *);
static int in6_ifinit (struct ifnet *, struct in6_ifaddr *,
                           struct sockaddr_in6 *, int);
static void in6_unlink_ifa (struct in6_ifaddr *, struct ifnet *);
static void in6_ifloop_request_callback(int, int, struct rt_addrinfo *, struct rtentry *, void *);

struct in6_multihead in6_multihead;     /* XXX BSS initialization */

int     (*faithprefix_p)(struct in6_addr *);

/*
 * Subroutine for in6_ifaddloop() and in6_ifremloop().
 * This routine does actual work.
 */
static void
in6_ifloop_request(int cmd, struct ifaddr *ifa)
{
        struct sockaddr_in6 all1_sa;
        struct rt_addrinfo rtinfo;
        int error;

        bzero(&all1_sa, sizeof(all1_sa));
        all1_sa.sin6_family = AF_INET6;
        all1_sa.sin6_len = sizeof(struct sockaddr_in6);
        all1_sa.sin6_addr = in6mask128;

        /*
         * We specify the address itself as the gateway, and set the
         * RTF_LLINFO flag, so that the corresponding host route would have
         * the flag, and thus applications that assume traditional behavior
         * would be happy.  Note that we assume the caller of the function
         * (probably implicitly) set nd6_rtrequest() to ifa->ifa_rtrequest,
         * which changes the outgoing interface to the loopback interface.
         */
        bzero(&rtinfo, sizeof(struct rt_addrinfo));
        rtinfo.rti_info[RTAX_DST] = ifa->ifa_addr;
        rtinfo.rti_info[RTAX_GATEWAY] = ifa->ifa_addr;
        rtinfo.rti_info[RTAX_NETMASK] = (struct sockaddr *)&all1_sa;
        rtinfo.rti_flags = RTF_UP|RTF_HOST|RTF_LLINFO;

        error = rtrequest1_global(cmd, &rtinfo,
                                  in6_ifloop_request_callback, ifa);
        if (error != 0) {
                log(LOG_ERR, "in6_ifloop_request: "
                    "%s operation failed for %s (errno=%d)\n",
                    cmd == RTM_ADD ? "ADD" : "DELETE",
                    ip6_sprintf(&((struct in6_ifaddr *)ifa)->ia_addr.sin6_addr),
                    error);
        }
}

static void
in6_ifloop_request_callback(int cmd, int error, struct rt_addrinfo *rtinfo,
                            struct rtentry *rt, void *arg)
{
        struct ifaddr *ifa = arg;

        if (error)
                goto done;

        /*
         * Make sure rt_ifa be equal to IFA, the second argument of the
         * function.
         * We need this because when we refer to rt_ifa->ia6_flags in
         * ip6_input, we assume that the rt_ifa points to the address instead
         * of the loopback address.
         */
        if (cmd == RTM_ADD && rt && ifa != rt->rt_ifa) {
                ++rt->rt_refcnt;
                IFAFREE(rt->rt_ifa);
                IFAREF(ifa);
                rt->rt_ifa = ifa;
                --rt->rt_refcnt;
        }

        /*
         * Report the addition/removal of the address to the routing socket.
         * XXX: since we called rtinit for a p2p interface with a destination,
         *      we end up reporting twice in such a case.  Should we rather
         *      omit the second report?
         */
        if (rt) {
                if (mycpuid == 0)
                        rt_newaddrmsg(cmd, ifa, error, rt);
                if (cmd == RTM_DELETE) {
                        if (rt->rt_refcnt == 0) {
                                ++rt->rt_refcnt;
                                rtfree(rt);
                        }
                }
        }
done:
        /* no way to return any new error */
        ;
}

/*
 * Add ownaddr as loopback rtentry.  We previously add the route only if
 * necessary (ex. on a p2p link).  However, since we now manage addresses
 * separately from prefixes, we should always add the route.  We can't
 * rely on the cloning mechanism from the corresponding interface route
 * any more.
 */
void
in6_ifaddloop(struct ifaddr *ifa)
{
        struct rtentry *rt;

        /* If there is no loopback entry, allocate one. */
        rt = rtpurelookup(ifa->ifa_addr);
        if (rt == NULL || !(rt->rt_flags & RTF_HOST) ||
            !(rt->rt_ifp->if_flags & IFF_LOOPBACK))
                in6_ifloop_request(RTM_ADD, ifa);
        if (rt != NULL)
                rt->rt_refcnt--;
}

/*
 * Remove loopback rtentry of ownaddr generated by in6_ifaddloop(),
 * if it exists.
 */
void
in6_ifremloop(struct ifaddr *ifa)
{
        struct in6_ifaddr *ia;
        struct rtentry *rt;
        int ia_count = 0;

        /*
         * Some of BSD variants do not remove cloned routes
         * from an interface direct route, when removing the direct route
         * (see comments in net/net_osdep.h).  Even for variants that do remove
         * cloned routes, they could fail to remove the cloned routes when
         * we handle multple addresses that share a common prefix.
         * So, we should remove the route corresponding to the deleted address
         * regardless of the result of in6_is_ifloop_auto().
         */

        /*
         * Delete the entry only if exact one ifa exists.  More than one ifa
         * can exist if we assign a same single address to multiple
         * (probably p2p) interfaces.
         * XXX: we should avoid such a configuration in IPv6...
         */
        for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                if (IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &ia->ia_addr.sin6_addr)) {
                        ia_count++;
                        if (ia_count > 1)
                                break;
                }
        }

        if (ia_count == 1) {
                /*
                 * Before deleting, check if a corresponding loopbacked host
                 * route surely exists.  With this check, we can avoid to
                 * delete an interface direct route whose destination is same
                 * as the address being removed.  This can happen when remofing
                 * a subnet-router anycast address on an interface attahced
                 * to a shared medium.
                 */
                rt = rtpurelookup(ifa->ifa_addr);
                if (rt != NULL && (rt->rt_flags & RTF_HOST) &&
                    (rt->rt_ifp->if_flags & IFF_LOOPBACK)) {
                        rt->rt_refcnt--;
                        in6_ifloop_request(RTM_DELETE, ifa);
                }
        }
}

int
in6_ifindex2scopeid(int idx)
{
        struct ifnet *ifp;
        struct sockaddr_in6 *sin6;
        struct ifaddr_container *ifac;

        if (idx < 0 || if_index < idx)
                return -1;
        ifp = ifindex2ifnet[idx];

        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link)
        {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
                if (IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr))
                        return sin6->sin6_scope_id & 0xffff;
        }

        return -1;
}

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

        if (lim0 == NULL ||
            lim0 - (u_char *)mask > sizeof(*mask)) /* ignore the scope_id part */
                lim = (u_char *)mask + sizeof(*mask);
        for (p = (u_char *)mask; p < lim; x++, p++) {
                if (*p != 0xff)
                        break;
        }
        y = 0;
        if (p < lim) {
                for (y = 0; y < 8; y++) {
                        if ((*p & (0x80 >> y)) == 0)
                                break;
                }
        }

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

        return x * 8 + y;
}

void
in6_len2mask(struct in6_addr *mask, int len)
{
        int i;

        bzero(mask, sizeof(*mask));
        for (i = 0; i < len / 8; i++)
                mask->s6_addr8[i] = 0xff;
        if (len % 8)
                mask->s6_addr8[i] = (0xff00 >> (len % 8)) & 0xff;
}

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

int
in6_control(struct socket *so, u_long cmd, caddr_t data,
            struct ifnet *ifp, struct thread *td)
{
        struct  in6_ifreq *ifr = (struct in6_ifreq *)data;
        struct  in6_ifaddr *ia = NULL;
        struct  in6_aliasreq *ifra = (struct in6_aliasreq *)data;
        int privileged;
        int error;

        privileged = 0;
        if (suser(td) == 0)
                privileged++;

        switch (cmd) {
        case SIOCGETSGCNT_IN6:
        case SIOCGETMIFCNT_IN6:
                return (mrt6_ioctl(cmd, data));
        }

        switch(cmd) {
        case SIOCAADDRCTL_POLICY:
        case SIOCDADDRCTL_POLICY:
                if (!privileged)
                        return (EPERM);
                return (in6_src_ioctl(cmd, data));
        }

        if (ifp == NULL)
                return (EOPNOTSUPP);

        switch (cmd) {
        case SIOCSNDFLUSH_IN6:
        case SIOCSPFXFLUSH_IN6:
        case SIOCSRTRFLUSH_IN6:
        case SIOCSDEFIFACE_IN6:
        case SIOCSIFINFO_FLAGS:
                if (!privileged)
                        return (EPERM);
                /* fall through */
        case OSIOCGIFINFO_IN6:
        case SIOCGIFINFO_IN6:
        case SIOCGDRLST_IN6:
        case SIOCGPRLST_IN6:
        case SIOCGNBRINFO_IN6:
        case SIOCGDEFIFACE_IN6:
                return (nd6_ioctl(cmd, data, ifp));
        }

        switch (cmd) {
        case SIOCSIFPREFIX_IN6:
        case SIOCDIFPREFIX_IN6:
        case SIOCAIFPREFIX_IN6:
        case SIOCCIFPREFIX_IN6:
        case SIOCSGIFPREFIX_IN6:
        case SIOCGIFPREFIX_IN6:
                log(LOG_NOTICE,
                    "prefix ioctls are now invalidated. "
                    "please use ifconfig.\n");
                return (EOPNOTSUPP);
        }

        switch (cmd) {
        case SIOCSSCOPE6:
                if (!privileged)
                        return (EPERM);
                return (scope6_set(ifp,
                        (struct scope6_id *)ifr->ifr_ifru.ifru_scope_id));
                break;
        case SIOCGSCOPE6:
                return (scope6_get(ifp,
                        (struct scope6_id *)ifr->ifr_ifru.ifru_scope_id));
                break;
        case SIOCGSCOPE6DEF:
                return (scope6_get_default((struct scope6_id *)
                        ifr->ifr_ifru.ifru_scope_id));
                break;
        }

        switch (cmd) {
        case SIOCALIFADDR:
        case SIOCDLIFADDR:
                if (!privileged)
                        return (EPERM);
                /* fall through */
        case SIOCGLIFADDR:
                return in6_lifaddr_ioctl(so, cmd, data, ifp, td);
        }

        /*
         * Find address for this interface, if it exists.
         */
        if (ifra->ifra_addr.sin6_family == AF_INET6) { /* XXX */
                struct sockaddr_in6 *sa6 =
                        (struct sockaddr_in6 *)&ifra->ifra_addr;

                if (IN6_IS_ADDR_LINKLOCAL(&sa6->sin6_addr)) {
                        if (sa6->sin6_addr.s6_addr16[1] == 0) {
                                /* link ID is not embedded by the user */
                                sa6->sin6_addr.s6_addr16[1] =
                                        htons(ifp->if_index);
                        } else if (sa6->sin6_addr.s6_addr16[1] !=
                                    htons(ifp->if_index)) {
                                return (EINVAL);        /* link ID contradicts */
                        }
                        if (sa6->sin6_scope_id) {
                                if (sa6->sin6_scope_id !=
                                    (u_int32_t)ifp->if_index)
                                        return (EINVAL);
                                sa6->sin6_scope_id = 0; /* XXX: good way? */
                        }
                }
                ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr);
        }

        switch (cmd) {
        case SIOCSIFADDR_IN6:
        case SIOCSIFDSTADDR_IN6:
        case SIOCSIFNETMASK_IN6:
                /*
                 * Since IPv6 allows a node to assign multiple addresses
                 * on a single interface, SIOCSIFxxx ioctls are not suitable
                 * and should be unused.
                 */
                /* we decided to obsolete this command (20000704) */
                return (EINVAL);

        case SIOCDIFADDR_IN6:
                /*
                 * for IPv4, we look for existing in_ifaddr here to allow
                 * "ifconfig if0 delete" to remove first IPv4 address on the
                 * interface.  For IPv6, as the spec allow multiple interface
                 * address from the day one, we consider "remove the first one"
                 * semantics to be not preferable.
                 */
                if (ia == NULL)
                        return (EADDRNOTAVAIL);
                /* FALLTHROUGH */
        case SIOCAIFADDR_IN6:
                /*
                 * We always require users to specify a valid IPv6 address for
                 * the corresponding operation.
                 */
                if (ifra->ifra_addr.sin6_family != AF_INET6 ||
                    ifra->ifra_addr.sin6_len != sizeof(struct sockaddr_in6))
                        return (EAFNOSUPPORT);
                if (!privileged)
                        return (EPERM);

                break;

        case SIOCGIFADDR_IN6:
                /* This interface is basically deprecated. use SIOCGIFCONF. */
                /* fall through */
        case SIOCGIFAFLAG_IN6:
        case SIOCGIFNETMASK_IN6:
        case SIOCGIFDSTADDR_IN6:
        case SIOCGIFALIFETIME_IN6:
                /* must think again about its semantics */
                if (ia == NULL)
                        return (EADDRNOTAVAIL);
                break;
        case SIOCSIFALIFETIME_IN6:
            {
                struct in6_addrlifetime *lt;

                if (!privileged)
                        return (EPERM);
                if (ia == NULL)
                        return (EADDRNOTAVAIL);
                /* sanity for overflow - beware unsigned */
                lt = &ifr->ifr_ifru.ifru_lifetime;
                if (lt->ia6t_vltime != ND6_INFINITE_LIFETIME
                 && lt->ia6t_vltime + time_second < time_second) {
                        return EINVAL;
                }
                if (lt->ia6t_pltime != ND6_INFINITE_LIFETIME
                 && lt->ia6t_pltime + time_second < time_second) {
                        return EINVAL;
                }
                break;
            }
        }

        switch (cmd) {

        case SIOCGIFADDR_IN6:
                ifr->ifr_addr = ia->ia_addr;
                break;

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

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

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

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

        case SIOCGIFSTAT_ICMP6:
                bzero(&ifr->ifr_ifru.ifru_stat,
                        sizeof(ifr->ifr_ifru.ifru_icmp6stat));
                ifr->ifr_ifru.ifru_icmp6stat =
                        *((struct in6_ifextra *)ifp->if_afdata[AF_INET6])->icmp6_ifstat;
                break;

        case SIOCGIFALIFETIME_IN6:
                ifr->ifr_ifru.ifru_lifetime = ia->ia6_lifetime;
                break;

        case SIOCSIFALIFETIME_IN6:
                ia->ia6_lifetime = ifr->ifr_ifru.ifru_lifetime;
                /* for sanity */
                if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                        ia->ia6_lifetime.ia6t_expire =
                                time_second + ia->ia6_lifetime.ia6t_vltime;
                } else
                        ia->ia6_lifetime.ia6t_expire = 0;
                if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                        ia->ia6_lifetime.ia6t_preferred =
                                time_second + ia->ia6_lifetime.ia6t_pltime;
                } else
                        ia->ia6_lifetime.ia6t_preferred = 0;
                break;

        case SIOCAIFADDR_IN6:
        {
                int i, error = 0, iaIsNew;
                struct nd_prefix pr0, *pr;

                if (ia != NULL)
                        iaIsNew = 0;
                else
                        iaIsNew = 1;

                /*
                 * first, make or update the interface address structure,
                 * and link it to the list.
                 */
                if ((error = in6_update_ifa(ifp, ifra, ia)) != 0)
                        return (error);

                /*
                 * then, make the prefix on-link on the interface.
                 * XXX: we'd rather create the prefix before the address, but
                 * we need at least one address to install the corresponding
                 * interface route, so we configure the address first.
                 */

                /*
                 * convert mask to prefix length (prefixmask has already
                 * been validated in in6_update_ifa().
                 */
                bzero(&pr0, sizeof(pr0));
                pr0.ndpr_ifp = ifp;
                pr0.ndpr_plen = in6_mask2len(&ifra->ifra_prefixmask.sin6_addr,
                                             NULL);
                if (pr0.ndpr_plen == 128)
                        break;  /* we don't need to install a host route. */
                pr0.ndpr_prefix = ifra->ifra_addr;
                pr0.ndpr_mask = ifra->ifra_prefixmask.sin6_addr;
                /* apply the mask for safety. */
                for (i = 0; i < 4; i++) {
                        pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
                                ifra->ifra_prefixmask.sin6_addr.s6_addr32[i];
                }
                /*
                 * XXX: since we don't have an API to set prefix (not address)
                 * lifetimes, we just use the same lifetimes as addresses.
                 * The (temporarily) installed lifetimes can be overridden by
                 * later advertised RAs (when accept_rtadv is non 0), which is
                 * an intended behavior.
                 */
                pr0.ndpr_raf_onlink = 1; /* should be configurable? */
                pr0.ndpr_raf_auto =
                        ((ifra->ifra_flags & IN6_IFF_AUTOCONF) != 0);
                pr0.ndpr_vltime = ifra->ifra_lifetime.ia6t_vltime;
                pr0.ndpr_pltime = ifra->ifra_lifetime.ia6t_pltime;

                /* add the prefix if there's one. */
                if ((pr = nd6_prefix_lookup(&pr0)) == NULL) {
                        /*
                         * nd6_prelist_add will install the corresponding
                         * interface route.
                         */
                        if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0)
                                return (error);
                        if (pr == NULL) {
                                log(LOG_ERR, "nd6_prelist_add succeeded but "
                                    "no prefix\n");
                                return (EINVAL); /* XXX panic here? */
                        }
                }
                if ((ia = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr))
                    == NULL) {
                        /* XXX: this should not happen! */
                        log(LOG_ERR, "in6_control: addition succeeded, but"
                            " no ifaddr\n");
                } else {
                        if ((ia->ia6_flags & IN6_IFF_AUTOCONF) &&
                            ia->ia6_ndpr == NULL) { /* new autoconfed addr */
                                ia->ia6_ndpr = pr;
                                pr->ndpr_refcnt++;

                                /*
                                 * If this is the first autoconf address from
                                 * the prefix, create a temporary address
                                 * as well (when specified).
                                 */
                                if (ip6_use_tempaddr &&
                                    pr->ndpr_refcnt == 1) {
                                        int e;
                                        if ((e = in6_tmpifadd(ia, 1)) != 0) {
                                                log(LOG_NOTICE, "in6_control: "
                                                    "failed to create a "
                                                    "temporary address, "
                                                    "errno=%d\n",
                                                    e);
                                        }
                                }
                        }

                        /*
                         * this might affect the status of autoconfigured
                         * addresses, that is, this address might make
                         * other addresses detached.
                         */
                        pfxlist_onlink_check();
                }
                if (error == 0 && ia) {
                        EVENTHANDLER_INVOKE(ifaddr_event, ifp,
                        iaIsNew ? IFADDR_EVENT_ADD : IFADDR_EVENT_CHANGE,
                        &ia->ia_ifa);
                }
                break;
        }

        case SIOCDIFADDR_IN6:
        {
                int i = 0;
                struct nd_prefix pr0, *pr;

                /*
                 * If the address being deleted is the only one that owns
                 * the corresponding prefix, expire the prefix as well.
                 * XXX: theoretically, we don't have to warry about such
                 * relationship, since we separate the address management
                 * and the prefix management.  We do this, however, to provide
                 * as much backward compatibility as possible in terms of
                 * the ioctl operation.
                 */
                bzero(&pr0, sizeof(pr0));
                pr0.ndpr_ifp = ifp;
                pr0.ndpr_plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr,
                                             NULL);
                if (pr0.ndpr_plen == 128)
                        goto purgeaddr;
                pr0.ndpr_prefix = ia->ia_addr;
                pr0.ndpr_mask = ia->ia_prefixmask.sin6_addr;
                for (i = 0; i < 4; i++) {
                        pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
                                ia->ia_prefixmask.sin6_addr.s6_addr32[i];
                }
                /*
                 * The logic of the following condition is a bit complicated.
                 * We expire the prefix when
                 * 1. the address obeys autoconfiguration and it is the
                 *    only owner of the associated prefix, or
                 * 2. the address does not obey autoconf and there is no
                 *    other owner of the prefix.
                 */
                if ((pr = nd6_prefix_lookup(&pr0)) != NULL &&
                    (((ia->ia6_flags & IN6_IFF_AUTOCONF) &&
                       pr->ndpr_refcnt == 1) ||
                     (!(ia->ia6_flags & IN6_IFF_AUTOCONF) &&
                      pr->ndpr_refcnt == 0))) {
                        pr->ndpr_expire = 1; /* XXX: just for expiration */
                }

purgeaddr:
                EVENTHANDLER_INVOKE(ifaddr_event, ifp, IFADDR_EVENT_DELETE,
                                    &ia->ia_ifa);
                in6_purgeaddr(&ia->ia_ifa);
                break;
        }

        default:
                if (ifp == NULL || ifp->if_ioctl == 0)
                        return (EOPNOTSUPP);
                lwkt_serialize_enter(ifp->if_serializer);
                error = ifp->if_ioctl(ifp, cmd, data, td->td_proc->p_ucred);
                lwkt_serialize_exit(ifp->if_serializer);
                return (error);
        }

        return (0);
}

/*
 * Update parameters of an IPv6 interface address.
 * If necessary, a new entry is created and linked into address chains.
 * This function is separated from in6_control().
 * XXX: should this be performed under splnet()?
 */
int
in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
               struct in6_ifaddr *ia)
{
        int error = 0, hostIsNew = 0, plen = -1;
        struct in6_ifaddr *oia;
        struct sockaddr_in6 dst6;
        struct in6_addrlifetime *lt;

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

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

                if ((error = in6_recoverscope(&dst6,
                                              &ifra->ifra_dstaddr.sin6_addr,
                                              ifp)) != 0)
                        return (error);
                scopeid = in6_addr2scopeid(ifp, &dst6.sin6_addr);
                if (dst6.sin6_scope_id == 0) /* user omit to specify the ID. */
                        dst6.sin6_scope_id = scopeid;
                else if (dst6.sin6_scope_id != scopeid)
                        return (EINVAL); /* scope ID mismatch. */
                if ((error = in6_embedscope(&dst6.sin6_addr, &dst6, NULL, NULL))
                    != 0)
                        return (error);
                dst6.sin6_scope_id = 0; /* XXX */
        }
        /*
         * The destination address can be specified only for a p2p or a
         * loopback interface.  If specified, the corresponding prefix length
         * must be 128.
         */
        if (ifra->ifra_dstaddr.sin6_family == AF_INET6) {
                if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) == 0) {
                        /* XXX: noisy message */
                        log(LOG_INFO, "in6_update_ifa: a destination can be "
                            "specified for a p2p or a loopback IF only\n");
                        return (EINVAL);
                }
                if (plen != 128) {
                        /*
                         * The following message seems noisy, but we dare to
                         * add it for diagnosis.
                         */
                        log(LOG_INFO, "in6_update_ifa: prefixlen must be 128 "
                            "when dstaddr is specified\n");
                        return (EINVAL);
                }
        }
        /* lifetime consistency check */
        lt = &ifra->ifra_lifetime;
        if (lt->ia6t_vltime != ND6_INFINITE_LIFETIME
            && lt->ia6t_vltime + time_second < time_second) {
                return EINVAL;
        }
        if (lt->ia6t_vltime == 0) {
                /*
                 * the following log might be noisy, but this is a typical
                 * configuration mistake or a tool's bug.
                 */
                log(LOG_INFO,
                    "in6_update_ifa: valid lifetime is 0 for %s\n",
                    ip6_sprintf(&ifra->ifra_addr.sin6_addr));
        }
        if (lt->ia6t_pltime != ND6_INFINITE_LIFETIME
            && lt->ia6t_pltime + time_second < time_second) {
                return EINVAL;
        }

        /*
         * If this is a new address, allocate a new ifaddr and link it
         * into chains.
         */
        if (ia == NULL) {
                hostIsNew = 1;
                /*
                 * When in6_update_ifa() is called in a process of a received
                 * RA, it is called under splnet().  So, we should call malloc
                 * with M_NOWAIT.
                 */
                ia = ifa_create(sizeof(*ia), M_NOWAIT);
                if (ia == NULL)
                        return (ENOBUFS);
                /* Initialize the address and masks */
                ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
                ia->ia_addr.sin6_family = AF_INET6;
                ia->ia_addr.sin6_len = sizeof(ia->ia_addr);
                if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) != 0) {
                        /*
                         * XXX: some functions expect that ifa_dstaddr is not
                         * NULL for p2p interfaces.
                         */
                        ia->ia_ifa.ifa_dstaddr
                                = (struct sockaddr *)&ia->ia_dstaddr;
                } else {
                        ia->ia_ifa.ifa_dstaddr = NULL;
                }
                ia->ia_ifa.ifa_netmask
                        = (struct sockaddr *)&ia->ia_prefixmask;

                ia->ia_ifp = ifp;
                if ((oia = in6_ifaddr) != NULL) {
                        for ( ; oia->ia_next; oia = oia->ia_next)
                                continue;
                        oia->ia_next = ia;
                } else
                        in6_ifaddr = ia;

                ifa_iflink(&ia->ia_ifa, ifp, 1);
        }

        /* set prefix mask */
        if (ifra->ifra_prefixmask.sin6_len) {
                /*
                 * We prohibit changing the prefix length of an existing
                 * address, because
                 * + such an operation should be rare in IPv6, and
                 * + the operation would confuse prefix management.
                 */
                if (ia->ia_prefixmask.sin6_len &&
                    in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL) != plen) {
                        log(LOG_INFO, "in6_update_ifa: the prefix length of an"
                            " existing (%s) address should not be changed\n",
                            ip6_sprintf(&ia->ia_addr.sin6_addr));
                        error = EINVAL;
                        goto unlink;
                }
                ia->ia_prefixmask = ifra->ifra_prefixmask;
        }

        /*
         * If a new destination address is specified, scrub the old one and
         * install the new destination.  Note that the interface must be
         * p2p or loopback (see the check above.)
         */
        if (dst6.sin6_family == AF_INET6 &&
            !IN6_ARE_ADDR_EQUAL(&dst6.sin6_addr,
                                &ia->ia_dstaddr.sin6_addr)) {
                int e;

                if ((ia->ia_flags & IFA_ROUTE) &&
                    (e = rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST))
                    != 0) {
                        log(LOG_ERR, "in6_update_ifa: failed to remove "
                            "a route to the old destination: %s\n",
                            ip6_sprintf(&ia->ia_addr.sin6_addr));
                        /* proceed anyway... */
                }
                else
                        ia->ia_flags &= ~IFA_ROUTE;
                ia->ia_dstaddr = dst6;
        }

        /* reset the interface and routing table appropriately. */
        if ((error = in6_ifinit(ifp, ia, &ifra->ifra_addr, hostIsNew)) != 0)
                goto unlink;

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

#if 0                           /* disable this mechanism for now */
        /* update prefix list */
        if (hostIsNew &&
            (ifra->ifra_flags & IN6_IFF_NOPFX) == 0) { /* XXX */
                int iilen;

                iilen = (sizeof(ia->ia_prefixmask.sin6_addr) << 3) - plen;
                if ((error = in6_prefix_add_ifid(iilen, ia)) != 0) {
                        in6_purgeaddr((struct ifaddr *)ia);
                        return (error);
                }
        }
#endif

        if (ifp->if_flags & IFF_MULTICAST) {
                struct sockaddr_in6 mltaddr, mltmask;
                struct in6_multi *in6m;

                if (hostIsNew) {
                        /*
                         * join solicited multicast addr for new host id
                         */
                        struct in6_addr llsol;
                        bzero(&llsol, sizeof(struct in6_addr));
                        llsol.s6_addr16[0] = htons(0xff02);
                        llsol.s6_addr16[1] = htons(ifp->if_index);
                        llsol.s6_addr32[1] = 0;
                        llsol.s6_addr32[2] = htonl(1);
                        llsol.s6_addr32[3] =
                                ifra->ifra_addr.sin6_addr.s6_addr32[3];
                        llsol.s6_addr8[12] = 0xff;
                        in6_addmulti(&llsol, ifp, &error);
                        if (error != 0) {
                                log(LOG_WARNING,
                                    "in6_update_ifa: addmulti failed for "
                                    "%s on %s (errno=%d)\n",
                                    ip6_sprintf(&llsol), if_name(ifp),
                                    error);
                                in6_purgeaddr((struct ifaddr *)ia);
                                return (error);
                        }
                }

                bzero(&mltmask, sizeof(mltmask));
                mltmask.sin6_len = sizeof(struct sockaddr_in6);
                mltmask.sin6_family = AF_INET6;
                mltmask.sin6_addr = in6mask32;

                /*
                 * join link-local all-nodes address
                 */
                bzero(&mltaddr, sizeof(mltaddr));
                mltaddr.sin6_len = sizeof(struct sockaddr_in6);
                mltaddr.sin6_family = AF_INET6;
                mltaddr.sin6_addr = kin6addr_linklocal_allnodes;
                mltaddr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);

                IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                if (in6m == NULL) {
                        rtrequest_global(RTM_ADD,
                                  (struct sockaddr *)&mltaddr,
                                  (struct sockaddr *)&ia->ia_addr,
                                  (struct sockaddr *)&mltmask,
                                  RTF_UP|RTF_CLONING);  /* xxx */
                        in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
                        if (error != 0) {
                                log(LOG_WARNING,
                                    "in6_update_ifa: addmulti failed for "
                                    "%s on %s (errno=%d)\n",
                                    ip6_sprintf(&mltaddr.sin6_addr),
                                    if_name(ifp), error);
                        }
                }

                /*
                 * join node information group address
                 */
#define hostnamelen     strlen(hostname)
                if (in6_nigroup(ifp, hostname, hostnamelen, &mltaddr.sin6_addr)
                    == 0) {
                        IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                        if (in6m == NULL && ia != NULL) {
                                in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
                                if (error != 0) {
                                        log(LOG_WARNING, "in6_update_ifa: "
                                            "addmulti failed for "
                                            "%s on %s (errno=%d)\n",
                                            ip6_sprintf(&mltaddr.sin6_addr),
                                            if_name(ifp), error);
                                }
                        }
                }
#undef hostnamelen

                /*
                 * join node-local all-nodes address, on loopback.
                 * XXX: since "node-local" is obsoleted by interface-local,
                 *      we have to join the group on every interface with
                 *      some interface-boundary restriction.
                 */
                if (ifp->if_flags & IFF_LOOPBACK) {
                        struct in6_ifaddr *ia_loop;

                        struct in6_addr loop6 = kin6addr_loopback;
                        ia_loop = in6ifa_ifpwithaddr(ifp, &loop6);

                        mltaddr.sin6_addr = kin6addr_nodelocal_allnodes;

                        IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                        if (in6m == NULL && ia_loop != NULL) {
                                rtrequest_global(RTM_ADD,
                                          (struct sockaddr *)&mltaddr,
                                          (struct sockaddr *)&ia_loop->ia_addr,
                                          (struct sockaddr *)&mltmask,
                                          RTF_UP);
                                in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
                                if (error != 0) {
                                        log(LOG_WARNING, "in6_update_ifa: "
                                            "addmulti failed for %s on %s "
                                            "(errno=%d)\n",
                                            ip6_sprintf(&mltaddr.sin6_addr),
                                            if_name(ifp), error);
                                }
                        }
                }
        }

        ia->ia6_flags = ifra->ifra_flags;
        ia->ia6_flags &= ~IN6_IFF_DUPLICATED;   /*safety*/
        ia->ia6_flags &= ~IN6_IFF_NODAD;        /* Mobile IPv6 */

        ia->ia6_lifetime = ifra->ifra_lifetime;
        /* for sanity */
        if (ia->ia6_lifetime.ia6t_vltime != ND6_INFINITE_LIFETIME) {
                ia->ia6_lifetime.ia6t_expire =
                        time_second + ia->ia6_lifetime.ia6t_vltime;
        } else
                ia->ia6_lifetime.ia6t_expire = 0;
        if (ia->ia6_lifetime.ia6t_pltime != ND6_INFINITE_LIFETIME) {
                ia->ia6_lifetime.ia6t_preferred =
                        time_second + ia->ia6_lifetime.ia6t_pltime;
        } else
                ia->ia6_lifetime.ia6t_preferred = 0;

        /*
         * Perform DAD, if needed.
         * XXX It may be of use, if we can administratively
         * disable DAD.
         */
        if (in6if_do_dad(ifp) && !(ifra->ifra_flags & IN6_IFF_NODAD)) {
                ia->ia6_flags |= IN6_IFF_TENTATIVE;
                nd6_dad_start((struct ifaddr *)ia, NULL);
        }

        return (error);

unlink:
        /*
         * XXX: if a change of an existing address failed, keep the entry
         * anyway.
         */
        if (hostIsNew)
                in6_unlink_ifa(ia, ifp);
        return (error);
}

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

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

        /*
         * delete route to the destination of the address being purged.
         * The interface must be p2p or loopback in this case.
         */
        if ((ia->ia_flags & IFA_ROUTE) && ia->ia_dstaddr.sin6_len != 0) {
                int e;

                if ((e = rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST))
                    != 0) {
                        log(LOG_ERR, "in6_purgeaddr: failed to remove "
                            "a route to the p2p destination: %s on %s, "
                            "errno=%d\n",
                            ip6_sprintf(&ia->ia_addr.sin6_addr), if_name(ifp),
                            e);
                        /* proceed anyway... */
                }
                else
                        ia->ia_flags &= ~IFA_ROUTE;
        }

        /* Remove ownaddr's loopback rtentry, if it exists. */
        in6_ifremloop(&(ia->ia_ifa));

        if (ifp->if_flags & IFF_MULTICAST) {
                /*
                 * delete solicited multicast addr for deleting host id
                 */
                struct in6_multi *in6m;
                struct in6_addr llsol;
                bzero(&llsol, sizeof(struct in6_addr));
                llsol.s6_addr16[0] = htons(0xff02);
                llsol.s6_addr16[1] = htons(ifp->if_index);
                llsol.s6_addr32[1] = 0;
                llsol.s6_addr32[2] = htonl(1);
                llsol.s6_addr32[3] =
                        ia->ia_addr.sin6_addr.s6_addr32[3];
                llsol.s6_addr8[12] = 0xff;

                IN6_LOOKUP_MULTI(llsol, ifp, in6m);
                if (in6m)
                        in6_delmulti(in6m);
        }

        in6_unlink_ifa(ia, ifp);
}

static void
in6_unlink_ifa(struct in6_ifaddr *ia, struct ifnet *ifp)
{
        int plen, iilen;
        struct in6_ifaddr *oia;

        crit_enter();

        ifa_ifunlink(&ia->ia_ifa, ifp);

        oia = ia;
        if (oia == (ia = in6_ifaddr))
                in6_ifaddr = ia->ia_next;
        else {
                while (ia->ia_next && (ia->ia_next != oia))
                        ia = ia->ia_next;
                if (ia->ia_next)
                        ia->ia_next = oia->ia_next;
                else {
                        /* search failed */
                        kprintf("Couldn't unlink in6_ifaddr from in6_ifaddr\n");
                }
        }

        if (oia->ia6_ifpr) {    /* check for safety */
                plen = in6_mask2len(&oia->ia_prefixmask.sin6_addr, NULL);
                iilen = (sizeof(oia->ia_prefixmask.sin6_addr) << 3) - plen;
                in6_prefix_remove_ifid(iilen, oia);
        }

        /*
         * When an autoconfigured address is being removed, release the
         * reference to the base prefix.  Also, since the release might
         * affect the status of other (detached) addresses, call
         * pfxlist_onlink_check().
         */
        if (oia->ia6_flags & IN6_IFF_AUTOCONF) {
                if (oia->ia6_ndpr == NULL) {
                        log(LOG_NOTICE, "in6_unlink_ifa: autoconf'ed address "
                            "%p has no prefix\n", oia);
                } else {
                        oia->ia6_ndpr->ndpr_refcnt--;
                        oia->ia6_flags &= ~IN6_IFF_AUTOCONF;
                        oia->ia6_ndpr = NULL;
                }

                pfxlist_onlink_check();
        }

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

        crit_exit();
}

void
in6_purgeif(struct ifnet *ifp)
{
        struct ifaddr_container *ifac, *next;

        TAILQ_FOREACH_MUTABLE(ifac, &ifp->if_addrheads[mycpuid],
                              ifa_link, next) {
                if (ifac->ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                in6_purgeaddr(ifac->ifa);
        }

        in6_ifdetach(ifp);
}

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

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

        switch (cmd) {
        case SIOCGLIFADDR:
                /* address must be specified on GET with IFLR_PREFIX */
                if (!(iflr->flags & IFLR_PREFIX))
                        break;
                /* FALLTHROUGH */
        case SIOCALIFADDR:
        case SIOCDLIFADDR:
                /* address must be specified on ADD and DELETE */
                sa = (struct sockaddr *)&iflr->addr;
                if (sa->sa_family != AF_INET6)
                        return EINVAL;
                if (sa->sa_len != sizeof(struct sockaddr_in6))
                        return EINVAL;
                /* XXX need improvement */
                sa = (struct sockaddr *)&iflr->dstaddr;
                if (sa->sa_family && sa->sa_family != AF_INET6)
                        return EINVAL;
                if (sa->sa_len && sa->sa_len != sizeof(struct sockaddr_in6))
                        return EINVAL;
                break;
        default: /* shouldn't happen */
#if 0
                panic("invalid cmd to in6_lifaddr_ioctl");
                /* NOTREACHED */
#else
                return EOPNOTSUPP;
#endif
        }
        if (sizeof(struct in6_addr) * 8 < iflr->prefixlen)
                return EINVAL;

        switch (cmd) {
        case SIOCALIFADDR:
            {
                struct in6_aliasreq ifra;
                struct in6_addr *hostid = NULL;
                int prefixlen;

                if (iflr->flags & IFLR_PREFIX) {
                        struct ifaddr *ifa;
                        struct sockaddr_in6 *sin6;

                        /*
                         * hostid is to fill in the hostid part of the
                         * address.  hostid points to the first link-local
                         * address attached to the interface.
                         */
                        ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp, 0);
                        if (!ifa)
                                return EADDRNOTAVAIL;
                        hostid = IFA_IN6(ifa);

                        /* prefixlen must be <= 64. */
                        if (64 < iflr->prefixlen)
                                return EINVAL;
                        prefixlen = iflr->prefixlen;

                        /* hostid part must be zero. */
                        sin6 = (struct sockaddr_in6 *)&iflr->addr;
                        if (sin6->sin6_addr.s6_addr32[2] != 0
                         || sin6->sin6_addr.s6_addr32[3] != 0) {
                                return EINVAL;
                        }
                } else
                        prefixlen = iflr->prefixlen;

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

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

                if (((struct sockaddr *)&iflr->dstaddr)->sa_family) {   /*XXX*/
                        bcopy(&iflr->dstaddr, &ifra.ifra_dstaddr,
                                ((struct sockaddr *)&iflr->dstaddr)->sa_len);
                        if (hostid) {
                                ifra.ifra_dstaddr.sin6_addr.s6_addr32[2] =
                                        hostid->s6_addr32[2];
                                ifra.ifra_dstaddr.sin6_addr.s6_addr32[3] =
                                        hostid->s6_addr32[3];
                        }
                }

                ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
                in6_len2mask(&ifra.ifra_prefixmask.sin6_addr, prefixlen);

                ifra.ifra_flags = iflr->flags & ~IFLR_PREFIX;
                return in6_control(so, SIOCAIFADDR_IN6, (caddr_t)&ifra, ifp, td);
            }
        case SIOCGLIFADDR:
        case SIOCDLIFADDR:
            {
                struct ifaddr_container *ifac;
                struct in6_ifaddr *ia;
                struct in6_addr mask, candidate, match;
                struct sockaddr_in6 *sin6;
                int cmp;

                bzero(&mask, sizeof(mask));
                if (iflr->flags & IFLR_PREFIX) {
                        /* lookup a prefix rather than address. */
                        in6_len2mask(&mask, iflr->prefixlen);

                        sin6 = (struct sockaddr_in6 *)&iflr->addr;
                        bcopy(&sin6->sin6_addr, &match, sizeof(match));
                        match.s6_addr32[0] &= mask.s6_addr32[0];
                        match.s6_addr32[1] &= mask.s6_addr32[1];
                        match.s6_addr32[2] &= mask.s6_addr32[2];
                        match.s6_addr32[3] &= mask.s6_addr32[3];

                        /* if you set extra bits, that's wrong */
                        if (bcmp(&match, &sin6->sin6_addr, sizeof(match)))
                                return EINVAL;

                        cmp = 1;
                } else {
                        if (cmd == SIOCGLIFADDR) {
                                /* on getting an address, take the 1st match */
                                cmp = 0;        /* XXX */
                        } else {
                                /* on deleting an address, do exact match */
                                in6_len2mask(&mask, 128);
                                sin6 = (struct sockaddr_in6 *)&iflr->addr;
                                bcopy(&sin6->sin6_addr, &match, sizeof(match));

                                cmp = 1;
                        }
                }

                TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                        struct ifaddr *ifa = ifac->ifa;

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

                        bcopy(IFA_IN6(ifa), &candidate, sizeof(candidate));
                        /*
                         * XXX: this is adhoc, but is necessary to allow
                         * a user to specify fe80::/64 (not /10) for a
                         * link-local address.
                         */
                        if (IN6_IS_ADDR_LINKLOCAL(&candidate))
                                candidate.s6_addr16[1] = 0;
                        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 (ifac == NULL)
                        return EADDRNOTAVAIL;
                ia = ifa2ia6(ifac->ifa);

                if (cmd == SIOCGLIFADDR) {
                        struct sockaddr_in6 *s6;

                        /* fill in the if_laddrreq structure */
                        bcopy(&ia->ia_addr, &iflr->addr, ia->ia_addr.sin6_len);
                        s6 = (struct sockaddr_in6 *)&iflr->addr;
                        if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr)) {
                                s6->sin6_addr.s6_addr16[1] = 0;
                                s6->sin6_scope_id =
                                        in6_addr2scopeid(ifp, &s6->sin6_addr);
                        }
                        if (ifp->if_flags & IFF_POINTOPOINT) {
                                bcopy(&ia->ia_dstaddr, &iflr->dstaddr,
                                        ia->ia_dstaddr.sin6_len);
                                s6 = (struct sockaddr_in6 *)&iflr->dstaddr;
                                if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr)) {
                                        s6->sin6_addr.s6_addr16[1] = 0;
                                        s6->sin6_scope_id =
                                                in6_addr2scopeid(ifp,
                                                                 &s6->sin6_addr);
                                }
                        } else
                                bzero(&iflr->dstaddr, sizeof(iflr->dstaddr));

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

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

                        return 0;
                } else {
                        struct in6_aliasreq ifra;

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

                        bcopy(&ia->ia_addr, &ifra.ifra_addr,
                              ia->ia_addr.sin6_len);
                        if (ifp->if_flags & IFF_POINTOPOINT)
                                bcopy(&ia->ia_dstaddr, &ifra.ifra_dstaddr,
                                      ia->ia_dstaddr.sin6_len);
                        else
                                bzero(&ifra.ifra_dstaddr,
                                      sizeof(ifra.ifra_dstaddr));
                        bcopy(&ia->ia_prefixmask, &ifra.ifra_dstaddr,
                              ia->ia_prefixmask.sin6_len);

                        ifra.ifra_flags = ia->ia6_flags;
                        return in6_control(so, SIOCDIFADDR_IN6, (caddr_t)&ifra,
                                ifp, td);
                }
            }
        }

        return EOPNOTSUPP;      /* just for safety */
}

/*
 * Initialize an interface's intetnet6 address
 * and routing table entry.
 */
static int
in6_ifinit(struct ifnet *ifp, struct in6_ifaddr *ia, struct sockaddr_in6 *sin6,
           int newhost)
{
        int     error = 0, plen, ifacount = 0;
        struct ifaddr_container *ifac;

        /*
         * Give the interface a chance to initialize
         * if this is its first address,
         * and to validate the address if necessary.
         */
        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                if (ifac->ifa->ifa_addr == NULL)
                        continue;       /* just for safety */
                if (ifac->ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ifacount++;
        }

        lwkt_serialize_enter(ifp->if_serializer);

        ia->ia_addr = *sin6;

        if (ifacount <= 1 && ifp->if_ioctl &&
            (error = ifp->if_ioctl(ifp, SIOCSIFADDR, (caddr_t)ia,
                                      (struct ucred *)NULL))) {
                lwkt_serialize_exit(ifp->if_serializer);
                return (error);
        }
        lwkt_serialize_exit(ifp->if_serializer);

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

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

        /*
         * Special case:
         * If the destination address is specified for a point-to-point
         * interface, install a route to the destination as an interface
         * direct route.
         */
        plen = in6_mask2len(&ia->ia_prefixmask.sin6_addr, NULL); /* XXX */
        if (plen == 128 && ia->ia_dstaddr.sin6_family == AF_INET6) {
                if ((error = rtinit(&(ia->ia_ifa), (int)RTM_ADD,
                                    RTF_UP | RTF_HOST)) != 0)
                        return (error);
                ia->ia_flags |= IFA_ROUTE;
        }
        if (plen < 128) {
                /*
                 * The RTF_CLONING flag is necessary for in6_is_ifloop_auto().
                 */
                ia->ia_ifa.ifa_flags |= RTF_CLONING;
        }

        /* Add ownaddr as loopback rtentry, if necessary (ex. on p2p link). */
        if (newhost) {
                /* set the rtrequest function to create llinfo */
                ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
                in6_ifaddloop(&(ia->ia_ifa));
        }

        return (error);
}

struct in6_multi_mship *
in6_joingroup(struct ifnet *ifp, struct in6_addr *addr, int *errorp)
{
       struct in6_multi_mship *imm;

       imm = kmalloc(sizeof(*imm), M_IPMADDR, M_NOWAIT);
       if (!imm) {
               *errorp = ENOBUFS;
               return NULL;
       }
       imm->i6mm_maddr = in6_addmulti(addr, ifp, errorp);
       if (!imm->i6mm_maddr) {
               /* *errorp is alrady set */
               kfree(imm, M_IPMADDR);
               return NULL;
       }
       return imm;
}

int
in6_leavegroup(struct in6_multi_mship *imm)
{

       if (imm->i6mm_maddr)
               in6_delmulti(imm->i6mm_maddr);
       kfree(imm,  M_IPMADDR);
       return 0;
}

/*
 * Add an address to the list of IP6 multicast addresses for a
 * given interface.
 */
struct  in6_multi *
in6_addmulti(struct in6_addr *maddr6, struct ifnet *ifp, int *errorp)
{
        struct  in6_multi *in6m;
        struct sockaddr_in6 sin6;
        struct ifmultiaddr *ifma;

        *errorp = 0;

        crit_enter();

        /*
         * Call generic routine to add membership or increment
         * refcount.  It wants addresses in the form of a sockaddr,
         * so we build one here (being careful to zero the unused bytes).
         */
        bzero(&sin6, sizeof sin6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_len = sizeof sin6;
        sin6.sin6_addr = *maddr6;
        *errorp = if_addmulti(ifp, (struct sockaddr *)&sin6, &ifma);
        if (*errorp) {
                crit_exit();
                return 0;
        }

        /*
         * If ifma->ifma_protospec is null, then if_addmulti() created
         * a new record.  Otherwise, we are done.
         */
        if (ifma->ifma_protospec != 0) {
                crit_exit();
                return ifma->ifma_protospec;
        }

        /* XXX - if_addmulti uses M_WAITOK.  Can this really be called
           at interrupt time?  If so, need to fix if_addmulti. XXX */
        in6m = (struct in6_multi *)kmalloc(sizeof(*in6m), M_IPMADDR, M_NOWAIT);
        if (in6m == NULL) {
                crit_exit();
                return (NULL);
        }

        bzero(in6m, sizeof *in6m);
        in6m->in6m_addr = *maddr6;
        in6m->in6m_ifp = ifp;
        in6m->in6m_ifma = ifma;
        ifma->ifma_protospec = in6m;
        LIST_INSERT_HEAD(&in6_multihead, in6m, in6m_entry);

        /*
         * Let MLD6 know that we have joined a new IP6 multicast
         * group.
         */
        mld6_start_listening(in6m);
        crit_exit();
        return (in6m);
}

/*
 * Delete a multicast address record.
 */
void
in6_delmulti(struct in6_multi *in6m)
{
        struct ifmultiaddr *ifma = in6m->in6m_ifma;

        crit_enter();

        if (ifma->ifma_refcount == 1) {
                /*
                 * No remaining claims to this record; let MLD6 know
                 * that we are leaving the multicast group.
                 */
                mld6_stop_listening(in6m);
                ifma->ifma_protospec = 0;
                LIST_REMOVE(in6m, in6m_entry);
                kfree(in6m, M_IPMADDR);
        }
        /* XXX - should be separate API for when we have an ifma? */
        if_delmulti(ifma->ifma_ifp, ifma->ifma_addr);
        crit_exit();
}

/*
 * Find an IPv6 interface link-local address specific to an interface.
 */
struct in6_ifaddr *
in6ifa_ifpforlinklocal(struct ifnet *ifp, int ignoreflags)
{
        struct ifaddr_container *ifac;

        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr == NULL)
                        continue;       /* just for safety */
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                if (IN6_IS_ADDR_LINKLOCAL(IFA_IN6(ifa))) {
                        if ((((struct in6_ifaddr *)ifa)->ia6_flags &
                             ignoreflags) != 0)
                                continue;
                        break;
                }
        }
        if (ifac != NULL)
                return ((struct in6_ifaddr *)(ifac->ifa));
        else
                return (NULL);
}


/*
 * find the internet address corresponding to a given interface and address.
 */
struct in6_ifaddr *
in6ifa_ifpwithaddr(struct ifnet *ifp, struct in6_addr *addr)
{
        struct ifaddr_container *ifac;

        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr == NULL)
                        continue;       /* just for safety */
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                if (IN6_ARE_ADDR_EQUAL(addr, IFA_IN6(ifa)))
                        break;
        }
        if (ifac != NULL)
                return ((struct in6_ifaddr *)(ifac->ifa));
        else
                return (NULL);
}

/*
 * find the internet address on a given interface corresponding to a neighbor's
 * address.
 */
struct in6_ifaddr *
in6ifa_ifplocaladdr(const struct ifnet *ifp, const struct in6_addr *addr)
{
        struct ifaddr *ifa;
        struct in6_ifaddr *ia;
        struct ifaddr_container *ifac;

        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                ifa = ifac->ifa;

                if (ifa->ifa_addr == NULL)
                        continue;       /* just for safety */
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ia = (struct in6_ifaddr *)ifa;
                if (IN6_ARE_MASKED_ADDR_EQUAL(addr,
                                &ia->ia_addr.sin6_addr,
                                &ia->ia_prefixmask.sin6_addr))
                        return ia;
        }

        return NULL;
}

/*
 * Convert IP6 address to printable (loggable) representation.
 */
static char digits[] = "0123456789abcdef";
static int ip6round = 0;
char *
ip6_sprintf(const struct in6_addr *addr)
{
        static char ip6buf[8][48];
        int i;
        char *cp;
        const u_short *a = (const u_short *)addr;
        const u_char *d;
        int dcolon = 0;

        ip6round = (ip6round + 1) & 7;
        cp = ip6buf[ip6round];

        for (i = 0; i < 8; i++) {
                if (dcolon == 1) {
                        if (*a == 0) {
                                if (i == 7)
                                        *cp++ = ':';
                                a++;
                                continue;
                        } else
                                dcolon = 2;
                }
                if (*a == 0) {
                        if (dcolon == 0 && *(a + 1) == 0) {
                                if (i == 0)
                                        *cp++ = ':';
                                *cp++ = ':';
                                dcolon = 1;
                        } else {
                                *cp++ = '0';
                                *cp++ = ':';
                        }
                        a++;
                        continue;
                }
                d = (const u_char *)a;
                *cp++ = digits[*d >> 4];
                *cp++ = digits[*d++ & 0xf];
                *cp++ = digits[*d >> 4];
                *cp++ = digits[*d & 0xf];
                *cp++ = ':';
                a++;
        }
        *--cp = 0;
        return (ip6buf[ip6round]);
}

int
in6_localaddr(struct in6_addr *in6)
{
        struct in6_ifaddr *ia;

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

        for (ia = in6_ifaddr; ia; ia = ia->ia_next)
                if (IN6_ARE_MASKED_ADDR_EQUAL(in6, &ia->ia_addr.sin6_addr,
                                              &ia->ia_prefixmask.sin6_addr))
                        return 1;

        return (0);
}

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

        for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                if (IN6_ARE_ADDR_EQUAL(&ia->ia_addr.sin6_addr,
                                       &sa6->sin6_addr) &&
                    (ia->ia6_flags & IN6_IFF_DEPRECATED))
                        return (1); /* true */

                /* XXX: do we still have to go thru the rest of the list? */
        }

        return (0);             /* false */
}

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

        while (s < lim)
                if ((r = (*d++ ^ *s++)) != 0) {
                        while (r < 128) {
                                match++;
                                r <<= 1;
                        }
                        break;
                } else
                        match += 8;
        return match;
}

/* XXX: to be scope conscious */
int
in6_are_prefix_equal(struct in6_addr *p1, struct in6_addr *p2, int len)
{
        int bytelen, bitlen;

        /* sanity check */
        if (0 > len || len > 128) {
                log(LOG_ERR, "in6_are_prefix_equal: invalid prefix length(%d)\n",
                    len);
                return (0);
        }

        bytelen = len / 8;
        bitlen = len % 8;

        if (bcmp(&p1->s6_addr, &p2->s6_addr, bytelen))
                return (0);
        if (p1->s6_addr[bytelen] >> (8 - bitlen) !=
            p2->s6_addr[bytelen] >> (8 - bitlen))
                return (0);

        return (1);
}

void
in6_prefixlen2mask(struct in6_addr *maskp, int len)
{
        u_char maskarray[8] = {0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};
        int bytelen, bitlen, i;

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

        bzero(maskp, sizeof(*maskp));
        bytelen = len / 8;
        bitlen = len % 8;
        for (i = 0; i < bytelen; i++)
                maskp->s6_addr[i] = 0xff;
        if (bitlen)
                maskp->s6_addr[bytelen] = maskarray[bitlen - 1];
}

/*
 * return the best address out of the same scope
 */
struct in6_ifaddr *
in6_ifawithscope(struct ifnet *oifp, struct in6_addr *dst)
{
        int dst_scope = in6_addrscope(dst), src_scope, best_scope = 0;
        int blen = -1;
        struct ifnet *ifp;
        struct in6_ifaddr *ifa_best = NULL;

        if (oifp == NULL) {
#if 0
                kprintf("in6_ifawithscope: output interface is not specified\n");
#endif
                return (NULL);
        }

        /*
         * We search for all addresses on all interfaces from the beginning.
         * Comparing an interface with the outgoing interface will be done
         * only at the final stage of tiebreaking.
         */
        for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
        {
                struct ifaddr_container *ifac;

                /*
                 * We can never take an address that breaks the scope zone
                 * of the destination.
                 */
                if (in6_addr2scopeid(ifp, dst) != in6_addr2scopeid(oifp, dst))
                        continue;

                TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                        int tlen = -1, dscopecmp, bscopecmp, matchcmp;
                        struct ifaddr *ifa = ifac->ifa;

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

                        src_scope = in6_addrscope(IFA_IN6(ifa));

                        /*
                         * Don't use an address before completing DAD
                         * nor a duplicated address.
                         */
                        if (((struct in6_ifaddr *)ifa)->ia6_flags &
                            IN6_IFF_NOTREADY)
                                continue;

                        /* XXX: is there any case to allow anycasts? */
                        if (((struct in6_ifaddr *)ifa)->ia6_flags &
                            IN6_IFF_ANYCAST)
                                continue;

                        if (((struct in6_ifaddr *)ifa)->ia6_flags &
                            IN6_IFF_DETACHED)
                                continue;

                        /*
                         * If this is the first address we find,
                         * keep it anyway.
                         */
                        if (ifa_best == NULL)
                                goto replace;

                        /*
                         * ifa_best is never NULL beyond this line except
                         * within the block labeled "replace".
                         */

                        /*
                         * If ifa_best has a smaller scope than dst and
                         * the current address has a larger one than
                         * (or equal to) dst, always replace ifa_best.
                         * Also, if the current address has a smaller scope
                         * than dst, ignore it unless ifa_best also has a
                         * smaller scope.
                         * Consequently, after the two if-clause below,
                         * the followings must be satisfied:
                         * (scope(src) < scope(dst) &&
                         *  scope(best) < scope(dst))
                         *  OR
                         * (scope(best) >= scope(dst) &&
                         *  scope(src) >= scope(dst))
                         */
                        if (IN6_ARE_SCOPE_CMP(best_scope, dst_scope) < 0 &&
                            IN6_ARE_SCOPE_CMP(src_scope, dst_scope) >= 0)
                                goto replace; /* (A) */
                        if (IN6_ARE_SCOPE_CMP(src_scope, dst_scope) < 0 &&
                            IN6_ARE_SCOPE_CMP(best_scope, dst_scope) >= 0)
                                continue; /* (B) */

                        /*
                         * A deprecated address SHOULD NOT be used in new
                         * communications if an alternate (non-deprecated)
                         * address is available and has sufficient scope.
                         * RFC 2462, Section 5.5.4.
                         */
                        if (((struct in6_ifaddr *)ifa)->ia6_flags &
                            IN6_IFF_DEPRECATED) {
                                /*
                                 * Ignore any deprecated addresses if
                                 * specified by configuration.
                                 */
                                if (!ip6_use_deprecated)
                                        continue;

                                /*
                                 * If we have already found a non-deprecated
                                 * candidate, just ignore deprecated addresses.
                                 */
                                if (!(ifa_best->ia6_flags & IN6_IFF_DEPRECATED))
                                        continue;
                        }

                        /*
                         * A non-deprecated address is always preferred
                         * to a deprecated one regardless of scopes and
                         * address matching (Note invariants ensured by the
                         * conditions (A) and (B) above.)
                         */
                        if ((ifa_best->ia6_flags & IN6_IFF_DEPRECATED) &&
                            !(((struct in6_ifaddr *)ifa)->ia6_flags &
                             IN6_IFF_DEPRECATED))
                                goto replace;

                        /*
                         * When we use temporary addresses described in
                         * RFC 3041, we prefer temporary addresses to
                         * public autoconf addresses.  Again, note the
                         * invariants from (A) and (B).  Also note that we
                         * don't have any preference between static addresses
                         * and autoconf addresses (despite of whether or not
                         * the latter is temporary or public.)
                         */
                        if (ip6_use_tempaddr) {
                                struct in6_ifaddr *ifat;

                                ifat = (struct in6_ifaddr *)ifa;
                                if ((ifa_best->ia6_flags &
                                     (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                     == IN6_IFF_AUTOCONF &&
                                    (ifat->ia6_flags &
                                     (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                     == (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY)) {
                                        goto replace;
                                }
                                if ((ifa_best->ia6_flags &
                                     (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                    == (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY) &&
                                    (ifat->ia6_flags &
                                     (IN6_IFF_AUTOCONF|IN6_IFF_TEMPORARY))
                                     == IN6_IFF_AUTOCONF) {
                                        continue;
                                }
                        }

                        /*
                         * At this point, we have two cases:
                         * 1. we are looking at a non-deprecated address,
                         *    and ifa_best is also non-deprecated.
                         * 2. we are looking at a deprecated address,
                         *    and ifa_best is also deprecated.
                         * Also, we do not have to consider a case where
                         * the scope of if_best is larger(smaller) than dst and
                         * the scope of the current address is smaller(larger)
                         * than dst. Such a case has already been covered.
                         * Tiebreaking is done according to the following
                         * items:
                         * - the scope comparison between the address and
                         *   dst (dscopecmp)
                         * - the scope comparison between the address and
                         *   ifa_best (bscopecmp)
                         * - if the address match dst longer than ifa_best
                         *   (matchcmp)
                         * - if the address is on the outgoing I/F (outI/F)
                         *
                         * Roughly speaking, the selection policy is
                         * - the most important item is scope. The same scope
                         *   is best. Then search for a larger scope.
                         *   Smaller scopes are the last resort.
                         * - A deprecated address is chosen only when we have
                         *   no address that has an enough scope, but is
                         *   prefered to any addresses of smaller scopes
                         *   (this must be already done above.)
                         * - addresses on the outgoing I/F are preferred to
                         *   ones on other interfaces if none of above
                         *   tiebreaks.  In the table below, the column "bI"
                         *   means if the best_ifa is on the outgoing
                         *   interface, and the column "sI" means if the ifa
                         *   is on the outgoing interface.
                         * - If there is no other reasons to choose one,
                         *   longest address match against dst is considered.
                         *
                         * The precise decision table is as follows:
                         * dscopecmp bscopecmp    match  bI oI | replace?
                         *       N/A     equal      N/A   Y  N |   No (1)
                         *       N/A     equal      N/A   N  Y |  Yes (2)
                         *       N/A     equal   larger    N/A |  Yes (3)
                         *       N/A     equal  !larger    N/A |   No (4)
                         *    larger    larger      N/A    N/A |   No (5)
                         *    larger   smaller      N/A    N/A |  Yes (6)
                         *   smaller    larger      N/A    N/A |  Yes (7)
                         *   smaller   smaller      N/A    N/A |   No (8)
                         *     equal   smaller      N/A    N/A |  Yes (9)
                         *     equal    larger       (already done at A above)
                         */
                        dscopecmp = IN6_ARE_SCOPE_CMP(src_scope, dst_scope);
                        bscopecmp = IN6_ARE_SCOPE_CMP(src_scope, best_scope);

                        if (bscopecmp == 0) {
                                struct ifnet *bifp = ifa_best->ia_ifp;

                                if (bifp == oifp && ifp != oifp) /* (1) */
                                        continue;
                                if (bifp != oifp && ifp == oifp) /* (2) */
                                        goto replace;

                                /*
                                 * Both bifp and ifp are on the outgoing
                                 * interface, or both two are on a different
                                 * interface from the outgoing I/F.
                                 * now we need address matching against dst
                                 * for tiebreaking.
                                 */
                                tlen = in6_matchlen(IFA_IN6(ifa), dst);
                                matchcmp = tlen - blen;
                                if (matchcmp > 0) /* (3) */
                                        goto replace;
                                continue; /* (4) */
                        }
                        if (dscopecmp > 0) {
                                if (bscopecmp > 0) /* (5) */
                                        continue;
                                goto replace; /* (6) */
                        }
                        if (dscopecmp < 0) {
                                if (bscopecmp > 0) /* (7) */
                                        goto replace;
                                continue; /* (8) */
                        }

                        /* now dscopecmp must be 0 */
                        if (bscopecmp < 0)
                                goto replace; /* (9) */

                  replace:
                        ifa_best = (struct in6_ifaddr *)ifa;
                        blen = tlen >= 0 ? tlen :
                                in6_matchlen(IFA_IN6(ifa), dst);
                        best_scope = in6_addrscope(&ifa_best->ia_addr.sin6_addr);
                }
        }

        /* count statistics for future improvements */
        if (ifa_best == NULL)
                ip6stat.ip6s_sources_none++;
        else {
                if (oifp == ifa_best->ia_ifp)
                        ip6stat.ip6s_sources_sameif[best_scope]++;
                else
                        ip6stat.ip6s_sources_otherif[best_scope]++;

                if (best_scope == dst_scope)
                        ip6stat.ip6s_sources_samescope[best_scope]++;
                else
                        ip6stat.ip6s_sources_otherscope[best_scope]++;

                if (ifa_best->ia6_flags & IN6_IFF_DEPRECATED)
                        ip6stat.ip6s_sources_deprecated[best_scope]++;
        }

        return (ifa_best);
}

/*
 * return the best address out of the same scope. if no address was
 * found, return the first valid address from designated IF.
 */
struct in6_ifaddr *
in6_ifawithifp(struct ifnet *ifp, struct in6_addr *dst)
{
        int dst_scope = in6_addrscope(dst), blen = -1, tlen;
        struct ifaddr_container *ifac;
        struct in6_ifaddr *besta = 0;
        struct in6_ifaddr *dep[2];      /* last-resort: deprecated */

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

        /*
         * We first look for addresses in the same scope.
         * If there is one, return it.
         * If two or more, return one which matches the dst longest.
         * If none, return one of global addresses assigned other ifs.
         */
        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_ANYCAST)
                        continue; /* XXX: is there any case to allow anycast? */
                if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_NOTREADY)
                        continue; /* don't use this interface */
                if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DETACHED)
                        continue;
                if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DEPRECATED) {
                        if (ip6_use_deprecated)
                                dep[0] = (struct in6_ifaddr *)ifa;
                        continue;
                }

                if (dst_scope == in6_addrscope(IFA_IN6(ifa))) {
                        /*
                         * call in6_matchlen() as few as possible
                         */
                        if (besta) {
                                if (blen == -1)
                                        blen = in6_matchlen(&besta->ia_addr.sin6_addr, dst);
                                tlen = in6_matchlen(IFA_IN6(ifa), dst);
                                if (tlen > blen) {
                                        blen = tlen;
                                        besta = (struct in6_ifaddr *)ifa;
                                }
                        } else
                                besta = (struct in6_ifaddr *)ifa;
                }
        }
        if (besta)
                return (besta);

        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

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

                return (struct in6_ifaddr *)ifa;
        }

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

        return NULL;
}

/*
 * perform DAD when interface becomes IFF_UP.
 */
void
in6_if_up(struct ifnet *ifp)
{
        struct ifaddr_container *ifac;
        struct in6_ifaddr *ia;
        int dad_delay;          /* delay ticks before DAD output */

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

        dad_delay = 0;
        TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
                struct ifaddr *ifa = ifac->ifa;

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ia = (struct in6_ifaddr *)ifa;
                if (ia->ia6_flags & IN6_IFF_TENTATIVE)
                        nd6_dad_start(ifa, &dad_delay);
        }
}

int
in6if_do_dad(struct ifnet *ifp)
{
        if (ifp->if_flags & IFF_LOOPBACK)
                return (0);

        switch (ifp->if_type) {
#ifdef IFT_DUMMY
        case IFT_DUMMY:
#endif
        case IFT_FAITH:
                /*
                 * These interfaces do not have the IFF_LOOPBACK flag,
                 * but loop packets back.  We do not have to do DAD on such
                 * interfaces.  We should even omit it, because loop-backed
                 * NS would confuse the DAD procedure.
                 */
                return (0);
        default:
                /*
                 * Our DAD routine requires the interface up and running.
                 * However, some interfaces can be up before the RUNNING
                 * status.  Additionaly, users may try to assign addresses
                 * before the interface becomes up (or running).
                 * We simply skip DAD in such a case as a work around.
                 * XXX: we should rather mark "tentative" on such addresses,
                 * and do DAD after the interface becomes ready.
                 */
                if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) !=
                    (IFF_UP|IFF_RUNNING))
                        return (0);

                return (1);
        }
}

/*
 * Calculate max IPv6 MTU through all the interfaces and store it
 * to in6_maxmtu.
 */
void
in6_setmaxmtu(void)
{
        unsigned long maxmtu = 0;
        struct ifnet *ifp;

        for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
        {
                if (!(ifp->if_flags & IFF_LOOPBACK) &&
                    ND_IFINFO(ifp)->linkmtu > maxmtu)
                        maxmtu =  ND_IFINFO(ifp)->linkmtu;
        }
        if (maxmtu)     /* update only when maxmtu is positive */
                in6_maxmtu = maxmtu;
}

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

        ext = (struct in6_ifextra *)kmalloc(sizeof(*ext), M_IFADDR, M_WAITOK);
        bzero(ext, sizeof(*ext));

        ext->in6_ifstat = (struct in6_ifstat *)kmalloc(sizeof(struct in6_ifstat),
                M_IFADDR, M_WAITOK);
        bzero(ext->in6_ifstat, sizeof(*ext->in6_ifstat));

        ext->icmp6_ifstat =
                (struct icmp6_ifstat *)kmalloc(sizeof(struct icmp6_ifstat),
                        M_IFADDR, M_WAITOK);
        bzero(ext->icmp6_ifstat, sizeof(*ext->icmp6_ifstat));

        ext->nd_ifinfo = nd6_ifattach(ifp);
        ext->scope6_id = scope6_ifattach(ifp);
        return ext;
}

void
in6_domifdetach(struct ifnet *ifp, void *aux)
{
        struct in6_ifextra *ext = (struct in6_ifextra *)aux;
        scope6_ifdetach(ext->scope6_id);
        nd6_ifdetach(ext->nd_ifinfo);
        kfree(ext->in6_ifstat, M_IFADDR);
        kfree(ext->icmp6_ifstat, M_IFADDR);
        kfree(ext, M_IFADDR);
}

/*
 * Convert sockaddr_in6 to sockaddr_in.  Original sockaddr_in6 must be
 * v4 mapped addr or v4 compat addr
 */
void
in6_sin6_2_sin(struct sockaddr_in *sin, struct sockaddr_in6 *sin6)
{
        bzero(sin, sizeof(*sin));
        sin->sin_len = sizeof(struct sockaddr_in);
        sin->sin_family = AF_INET;
        sin->sin_port = sin6->sin6_port;
        sin->sin_addr.s_addr = sin6->sin6_addr.s6_addr32[3];
}

/* Convert sockaddr_in to sockaddr_in6 in v4 mapped addr format. */
void
in6_sin_2_v4mapsin6(struct sockaddr_in *sin, struct sockaddr_in6 *sin6)
{
        bzero(sin6, sizeof(*sin6));
        sin6->sin6_len = sizeof(struct sockaddr_in6);
        sin6->sin6_family = AF_INET6;
        sin6->sin6_port = sin->sin_port;
        sin6->sin6_addr.s6_addr32[0] = 0;
        sin6->sin6_addr.s6_addr32[1] = 0;
        sin6->sin6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
        sin6->sin6_addr.s6_addr32[3] = sin->sin_addr.s_addr;
}

/* Convert sockaddr_in6 into sockaddr_in. */
void
in6_sin6_2_sin_in_sock(struct sockaddr *nam)
{
        struct sockaddr_in *sin_p;
        struct sockaddr_in6 sin6;

        /*
         * Save original sockaddr_in6 addr and convert it
         * to sockaddr_in.
         */
        sin6 = *(struct sockaddr_in6 *)nam;
        sin_p = (struct sockaddr_in *)nam;
        in6_sin6_2_sin(sin_p, &sin6);
}

/* Convert sockaddr_in into sockaddr_in6 in v4 mapped addr format. */
void
in6_sin_2_v4mapsin6_in_sock(struct sockaddr **nam)
{
        struct sockaddr_in *sin_p;
        struct sockaddr_in6 *sin6_p;

        MALLOC(sin6_p, struct sockaddr_in6 *, sizeof *sin6_p, M_SONAME,
               M_WAITOK);
        sin_p = (struct sockaddr_in *)*nam;
        in6_sin_2_v4mapsin6(sin_p, sin6_p);
        FREE(*nam, M_SONAME);
        *nam = (struct sockaddr *)sin6_p;
}