xnu-1504.9.26.tar.gz

[apple/xnu.git] / bsd / netinet6 / in6_ifattach.c

/*
 * Copyright (c) 2003-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
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 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*      $FreeBSD: src/sys/netinet6/in6_ifattach.c,v 1.8 2002/04/19 04:46:22 suz Exp $   */
/*      $KAME: in6_ifattach.c,v 1.118 2001/05/24 07:44:00 itojun Exp $  */

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sockio.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <libkern/crypto/md5.h>
#include <libkern/OSAtomic.h>
#include <kern/lock.h>

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

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

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

#include <net/net_osdep.h>

struct in6_ifstat **in6_ifstat = NULL;
struct icmp6_ifstat **icmp6_ifstat = NULL;
size_t in6_ifstatmax = 0;
size_t icmp6_ifstatmax = 0;
u_int32_t in6_maxmtu = 0;
extern lck_mtx_t *nd6_mutex;
extern lck_mtx_t *inet6_domain_mutex;

#if IP6_AUTO_LINKLOCAL
int ip6_auto_linklocal = IP6_AUTO_LINKLOCAL;
#else
int ip6_auto_linklocal = 1;     /* enable by default */
#endif

extern struct inpcbinfo udbinfo;
extern struct inpcbinfo ripcbinfo;
extern lck_mtx_t *ip6_mutex;

static int get_rand_ifid(struct ifnet *, struct in6_addr *);
static int generate_tmp_ifid(u_int8_t *, const u_int8_t *, u_int8_t *);
static int get_hw_ifid(struct ifnet *, struct in6_addr *);
static int get_ifid(struct ifnet *, struct ifnet *, struct in6_addr *);
static int in6_ifattach_linklocal(struct ifnet *, struct ifnet *, struct in6_aliasreq *);
static int in6_ifattach_loopback(struct ifnet *);

#define EUI64_GBIT      0x01
#define EUI64_UBIT      0x02
#define EUI64_TO_IFID(in6)      do {(in6)->s6_addr[8] ^= EUI64_UBIT; } while (0)
#define EUI64_GROUP(in6)        ((in6)->s6_addr[8] & EUI64_GBIT)
#define EUI64_INDIVIDUAL(in6)   (!EUI64_GROUP(in6))
#define EUI64_LOCAL(in6)        ((in6)->s6_addr[8] & EUI64_UBIT)
#define EUI64_UNIVERSAL(in6)    (!EUI64_LOCAL(in6))

#define IFID_LOCAL(in6)         (!EUI64_LOCAL(in6))
#define IFID_UNIVERSAL(in6)     (!EUI64_UNIVERSAL(in6))

/*
 * Generate a last-resort interface identifier, when the machine has no
 * IEEE802/EUI64 address sources.
 * The goal here is to get an interface identifier that is
 * (1) random enough and (2) does not change across reboot.
 * We currently use MD5(hostname) for it.
 */
static int
get_rand_ifid(
        __unused struct ifnet *ifp,
        struct in6_addr *in6)   /* upper 64bits are preserved */
{
        MD5_CTX ctxt;
        u_int8_t digest[16];
        int len = strlen(hostname);

#if 0
        /* we need at least several letters as seed for ifid */
        if (len < 3)
                return -1;
#endif

        /* generate 8 bytes of pseudo-random value. */
        bzero(&ctxt, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, hostname, len);
        MD5Final(digest, &ctxt);

        /* assumes sizeof(digest) > sizeof(ifid) */
        bcopy(digest, &in6->s6_addr[8], 8);

        /* make sure to set "u" bit to local, and "g" bit to individual. */
        in6->s6_addr[8] &= ~EUI64_GBIT; /* g bit to "individual" */
        in6->s6_addr[8] |= EUI64_UBIT;  /* u bit to "local" */

        /* convert EUI64 into IPv6 interface identifier */
        EUI64_TO_IFID(in6);

        return 0;
}

static int
generate_tmp_ifid(
        u_int8_t *seed0,
        const u_int8_t *seed1,
        u_int8_t *ret)
{
        MD5_CTX ctxt;
        u_int8_t seed[16], digest[16], nullbuf[8];
        u_int32_t val32;
        struct timeval tv;

        /* If there's no hisotry, start with a random seed. */
        bzero(nullbuf, sizeof(nullbuf));
        if (bcmp(nullbuf, seed0, sizeof(nullbuf)) == 0) {
                int i;

                for (i = 0; i < 2; i++) {
                        microtime(&tv);
                        val32 = random() ^ tv.tv_usec;
                        bcopy(&val32, seed + sizeof(val32) * i, sizeof(val32));
                }
        } else {
                bcopy(seed0, seed, 8);
        }

        /* copy the right-most 64-bits of the given address */
        /* XXX assumption on the size of IFID */
        bcopy(seed1, &seed[8], 8);

        if (0) {                /* for debugging purposes only */
                int i;

                printf("generate_tmp_ifid: new randomized ID from: ");
                for (i = 0; i < 16; i++)
                        printf("%02x", seed[i]);
                printf(" ");
        }

        /* generate 16 bytes of pseudo-random value. */
        bzero(&ctxt, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, seed, sizeof(seed));
        MD5Final(digest, &ctxt);

        /*
         * RFC 3041 3.2.1. (3)
         * Take the left-most 64-bits of the MD5 digest and set bit 6 (the
         * left-most bit is numbered 0) to zero.
         */
        bcopy(digest, ret, 8);
        ret[0] &= ~EUI64_UBIT;

        /*
         * XXX: we'd like to ensure that the generated value is not zero
         * for simplicity.  If the caclculated digest happens to be zero,
         * use a random non-zero value as the last resort.
         */
        if (bcmp(nullbuf, ret, sizeof(nullbuf)) == 0) {
                log(LOG_INFO,
                    "generate_tmp_ifid: computed MD5 value is zero.\n");

                microtime(&tv);
                val32 = random() ^ tv.tv_usec;
                val32 = 1 + (val32 % (0xffffffff - 1));
        }

        /*
         * RFC 3041 3.2.1. (4)
         * Take the rightmost 64-bits of the MD5 digest and save them in
         * stable storage as the history value to be used in the next
         * iteration of the algorithm. 
         */
        bcopy(&digest[8], seed0, 8);

        if (0) {                /* for debugging purposes only */
                int i;

                printf("to: ");
                for (i = 0; i < 16; i++)
                        printf("%02x", digest[i]);
                printf("\n");
        }

        return 0;
}

/*
 * Get interface identifier for the specified interface.
 * XXX assumes single sockaddr_dl (AF_LINK address) per an interface
 */
static int
get_hw_ifid(
        struct ifnet *ifp,
        struct in6_addr *in6)   /* upper 64bits are preserved */
{
        struct ifaddr *ifa;
        struct sockaddr_dl *sdl;
        u_int8_t *addr;
        size_t addrlen;
        static u_int8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
        static u_int8_t allone[8] =
                { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

        /* Why doesn't this code use ifnet_addrs? */
        ifnet_lock_shared(ifp);
        for (ifa = ifp->if_addrlist.tqh_first;
             ifa;
             ifa = ifa->ifa_list.tqe_next)
        {
                if (ifa->ifa_addr->sa_family != AF_LINK)
                        continue;
                sdl = (struct sockaddr_dl *)ifa->ifa_addr;
                if (sdl == NULL)
                        continue;
                if (sdl->sdl_alen == 0)
                        continue;

                goto found;
        }
        ifnet_lock_done(ifp);

        return -1;

found:
        ifnet_lock_done(ifp);
        addr = (u_int8_t *) LLADDR(sdl);
        addrlen = sdl->sdl_alen;

        /* get EUI64 */
        switch (ifp->if_type) {
        case IFT_ETHER:
        case IFT_FDDI:
        case IFT_ATM:
        case IFT_IEEE1394:
        case IFT_L2VLAN:
        case IFT_IEEE8023ADLAG:
#if IFT_IEEE80211
        case IFT_IEEE80211:
#endif
        case IFT_BRIDGE:
                /* IEEE802/EUI64 cases - what others? */
                /* IEEE1394 uses 16byte length address starting with EUI64 */
                if (addrlen > 8)
                        addrlen = 8;

                /* look at IEEE802/EUI64 only */
                if (addrlen != 8 && addrlen != 6)
                        return -1;

                /*
                 * check for invalid MAC address - on bsdi, we see it a lot
                 * since wildboar configures all-zero MAC on pccard before
                 * card insertion.
                 */
                if (bcmp(addr, allzero, addrlen) == 0)
                        return -1;
                if (bcmp(addr, allone, addrlen) == 0)
                        return -1;

                /* make EUI64 address */
                if (addrlen == 8)
                        bcopy(addr, &in6->s6_addr[8], 8);
                else if (addrlen == 6) {
                        in6->s6_addr[8] = addr[0];
                        in6->s6_addr[9] = addr[1];
                        in6->s6_addr[10] = addr[2];
                        in6->s6_addr[11] = 0xff;
                        in6->s6_addr[12] = 0xfe;
                        in6->s6_addr[13] = addr[3];
                        in6->s6_addr[14] = addr[4];
                        in6->s6_addr[15] = addr[5];
                }
                break;

        case IFT_ARCNET:
                if (addrlen != 1)
                        return -1;
                if (!addr[0])
                        return -1;

                bzero(&in6->s6_addr[8], 8);
                in6->s6_addr[15] = addr[0];

                /*
                 * due to insufficient bitwidth, we mark it local.
                 */
                in6->s6_addr[8] &= ~EUI64_GBIT; /* g bit to "individual" */
                in6->s6_addr[8] |= EUI64_UBIT;  /* u bit to "local" */
                break;

        case IFT_GIF:
#if IFT_STF
        case IFT_STF:
#endif
                /*
                 * RFC2893 says: "SHOULD use IPv4 address as ifid source".
                 * however, IPv4 address is not very suitable as unique
                 * identifier source (can be renumbered).
                 * we don't do this.
                 */
                return -1;

        default:
                return -1;
        }

        /* sanity check: g bit must not indicate "group" */
        if (EUI64_GROUP(in6))
                return -1;

        /* convert EUI64 into IPv6 interface identifier */
        EUI64_TO_IFID(in6);

        /*
         * sanity check: ifid must not be all zero, avoid conflict with
         * subnet router anycast
         */
        if ((in6->s6_addr[8] & ~(EUI64_GBIT | EUI64_UBIT)) == 0x00 &&
            bcmp(&in6->s6_addr[9], allzero, 7) == 0) {
                return -1;
        }

        return 0;
}

/*
 * Get interface identifier for the specified interface.  If it is not
 * available on ifp0, borrow interface identifier from other information
 * sources.
 */
static int
get_ifid(
        struct ifnet *ifp0,
        struct ifnet *altifp,   /* secondary EUI64 source */
        struct in6_addr *in6)
{
        struct ifnet *ifp;

        /* first, try to get it from the interface itself */
        if (get_hw_ifid(ifp0, in6) == 0) {
                nd6log((LOG_DEBUG, "%s: got interface identifier from itself\n",
                    if_name(ifp0)));
                goto success;
        }

        /* try secondary EUI64 source. this basically is for ATM PVC */
        if (altifp && get_hw_ifid(altifp, in6) == 0) {
                nd6log((LOG_DEBUG, "%s: got interface identifier from %s\n",
                    if_name(ifp0), if_name(altifp)));
                goto success;
        }

        /* next, try to get it from some other hardware interface */
        ifnet_head_lock_shared();
        TAILQ_FOREACH(ifp, &ifnet_head, if_list) {
                if (ifp == ifp0)
                        continue;
                if (get_hw_ifid(ifp, in6) != 0)
                        continue;

                /*
                 * to borrow ifid from other interface, ifid needs to be
                 * globally unique
                 */
                if (IFID_UNIVERSAL(in6)) {
                        nd6log((LOG_DEBUG,
                            "%s: borrow interface identifier from %s\n",
                            if_name(ifp0), if_name(ifp)));
                        ifnet_head_done();
                        goto success;
                }
        }
        ifnet_head_done();

        /* last resort: get from random number source */
        if (get_rand_ifid(ifp, in6) == 0) {
                nd6log((LOG_DEBUG,
                    "%s: interface identifier generated by random number\n",
                    if_name(ifp0)));
                goto success;
        }

        printf("%s: failed to get interface identifier\n", if_name(ifp0));
        return -1;

success:
        nd6log((LOG_INFO, "%s: ifid: "
                "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
                if_name(ifp0),
                in6->s6_addr[8], in6->s6_addr[9],
                in6->s6_addr[10], in6->s6_addr[11],
                in6->s6_addr[12], in6->s6_addr[13],
                in6->s6_addr[14], in6->s6_addr[15]));
        return 0;
}

static int
in6_ifattach_linklocal(
        struct ifnet *ifp,
        struct ifnet *altifp,   /* secondary EUI64 source */
        struct in6_aliasreq *ifra_passed)
{
        struct in6_ifaddr *ia;
        struct in6_aliasreq ifra;
        struct nd_prefix pr0, *pr;
        int i, error;

        /*
         * configure link-local address.
         */
        bzero(&ifra, sizeof(ifra));

        proto_plumb(PF_INET6, ifp);

        /*
         * in6_update_ifa() does not use ifra_name, but we accurately set it
         * for safety.
         */
        strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));

        if (((ifp->if_type == IFT_PPP) ||  ((ifp->if_eflags & IFEF_NOAUTOIPV6LL) != 0)) &&
                         ifra_passed != NULL)  /* PPP provided both addresses for us */
                bcopy(&ifra_passed->ifra_addr, &(ifra.ifra_addr), sizeof(struct sockaddr_in6));
        else {
                ifra.ifra_addr.sin6_family = AF_INET6;
                ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
                ifra.ifra_addr.sin6_addr.s6_addr16[0] = htons(0xfe80);
#if SCOPEDROUTING
                ifra.ifra_addr.sin6_addr.s6_addr16[1] = 0
#else
                ifra.ifra_addr.sin6_addr.s6_addr16[1] = htons(ifp->if_index); /* XXX */
#endif
                ifra.ifra_addr.sin6_addr.s6_addr32[1] = 0;
                if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                        ifra.ifra_addr.sin6_addr.s6_addr32[2] = 0;
                        ifra.ifra_addr.sin6_addr.s6_addr32[3] = htonl(1);
                } else {
                        if (get_ifid(ifp, altifp, &ifra.ifra_addr.sin6_addr) != 0) {
                                nd6log((LOG_ERR,
                            "   %s: no ifid available\n", if_name(ifp)));
                                return -1;
                        }
                }
#if SCOPEDROUTING
                ifra.ifra_addr.sin6_scope_id =
                        in6_addr2scopeid(ifp,  &ifra.ifra_addr.sin6_addr);
#endif
        }
        ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
        ifra.ifra_prefixmask.sin6_family = AF_INET6;
        ifra.ifra_prefixmask.sin6_addr = in6mask64;
#if SCOPEDROUTING
        /* take into accound the sin6_scope_id field for routing */
        ifra.ifra_prefixmask.sin6_scope_id = 0xffffffff;
#endif
        /* link-local addresses should NEVER expire. */
        ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
        ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;

        /*
         * Do not let in6_update_ifa() do DAD, since we need a random delay
         * before sending an NS at the first time the interface becomes up.
         * Instead, in6_if_up() will start DAD with a proper random delay.
         */
        ifra.ifra_flags |= IN6_IFF_NODAD;

        /*
         * Now call in6_update_ifa() to do a bunch of procedures to configure
         * a link-local address. We can set NULL to the 3rd argument, because
         * we know there's no other link-local address on the interface
         * and therefore we are adding one (instead of updating one).
         */
        if ((error = in6_update_ifa(ifp, &ifra, NULL, M_WAITOK)) != 0) {
                /*
                 * XXX: When the interface does not support IPv6, this call
                 * would fail in the SIOCSIFADDR ioctl.  I believe the
                 * notification is rather confusing in this case, so just
                 * supress it.  (jinmei@kame.net 20010130)
                 */
                if (error != EAFNOSUPPORT)
                        log(LOG_NOTICE, "in6_ifattach_linklocal: failed to "
                            "configure a link-local address on %s "
                            "(errno=%d)\n",
                            if_name(ifp), error);
                return(-1);
        }

        /*
         * Adjust ia6_flags so that in6_if_up will perform DAD.
         * XXX: Some P2P interfaces seem not to send packets just after
         * becoming up, so we skip p2p interfaces for safety.
         */
        ia = in6ifa_ifpforlinklocal(ifp, 0); /* ia must not be NULL */
#if DIAGNOSTIC
        if (!ia) {
                panic("ia == NULL in in6_ifattach_linklocal");
                /*NOTREACHED*/
        }
#endif
        if (in6if_do_dad(ifp) && (ifp->if_flags & IFF_POINTOPOINT) == 0) {
                ia->ia6_flags &= ~IN6_IFF_NODAD;
                ia->ia6_flags |= IN6_IFF_TENTATIVE;
        }

        /*
         * Make the link-local prefix (fe80::/64%link) as on-link.
         * Since we'd like to manage prefixes separately from addresses,
         * we make an ND6 prefix structure for the link-local prefix,
         * and add it to the prefix list as a never-expire prefix.
         * XXX: this change might affect some existing code base...
         */
        bzero(&pr0, sizeof(pr0));
        pr0.ndpr_ifp = ifp;
        /* this should be 64 at this moment. */
        pr0.ndpr_plen = in6_mask2len(&ifra.ifra_prefixmask.sin6_addr, NULL);
        pr0.ndpr_mask = ifra.ifra_prefixmask.sin6_addr;
        pr0.ndpr_prefix = ifra.ifra_addr;
        /* apply the mask for safety. (nd6_prelist_add will apply it again) */
        for (i = 0; i < 4; i++) {
                pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
                        in6mask64.s6_addr32[i];
        }
        /*
         * Initialize parameters.  The link-local prefix must always be
         * on-link, and its lifetimes never expire.
         */
        pr0.ndpr_raf_onlink = 1;
        pr0.ndpr_raf_auto = 1;  /* probably meaningless */
        pr0.ndpr_vltime = ND6_INFINITE_LIFETIME;
        pr0.ndpr_pltime = ND6_INFINITE_LIFETIME;
        /*
         * Since there is no other link-local addresses, nd6_prefix_lookup()
         * probably returns NULL.  However, we cannot always expect the result.
         * For example, if we first remove the (only) existing link-local
         * address, and then reconfigure another one, the prefix is still
         * valid with referring to the old link-local address.
         */
        if ((pr = nd6_prefix_lookup(&pr0)) == NULL) {
                if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0) {
                        printf("in6_ifattach_linklocal: nd6_prelist_add failed %d\n", error);
                        ifafree(&ia->ia_ifa);
                        return(error);
                }
        }

        if (ia != NULL) {
                in6_post_msg(ifp, KEV_INET6_NEW_LL_ADDR, ia);
                ifafree(&ia->ia_ifa);
        }

        /* Drop use count held above during lookup/add */
        if (pr != NULL)
                ndpr_rele(pr, FALSE);

        return 0;
}

static int
in6_ifattach_loopback(
        struct ifnet *ifp)      /* must be IFT_LOOP */
{
        struct in6_aliasreq ifra;
        int error;

        bzero(&ifra, sizeof(ifra));

        /*
         * in6_update_ifa() does not use ifra_name, but we accurately set it
         * for safety.
         */
        strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));

        ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
        ifra.ifra_prefixmask.sin6_family = AF_INET6;
        ifra.ifra_prefixmask.sin6_addr = in6mask128;

        /*
         * Always initialize ia_dstaddr (= broadcast address) to loopback
         * address.  Follows IPv4 practice - see in_ifinit().
         */
        ifra.ifra_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
        ifra.ifra_dstaddr.sin6_family = AF_INET6;
        ifra.ifra_dstaddr.sin6_addr = in6addr_loopback;

        ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
        ifra.ifra_addr.sin6_family = AF_INET6;
        ifra.ifra_addr.sin6_addr = in6addr_loopback;

        /* the loopback  address should NEVER expire. */
        ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
        ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;

        /* we don't need to perform DAD on loopback interfaces. */
        ifra.ifra_flags |= IN6_IFF_NODAD;

        /* skip registration to the prefix list. XXX should be temporary. */
        ifra.ifra_flags |= IN6_IFF_NOPFX;

        /*
         * We are sure that this is a newly assigned address, so we can set
         * NULL to the 3rd arg.
         */
        if ((error = in6_update_ifa(ifp, &ifra, NULL, M_WAITOK)) != 0) {
                log(LOG_ERR, "in6_ifattach_loopback: failed to configure "
                    "the loopback address on %s (errno=%d)\n",
                    if_name(ifp), error);
                return(-1);
        }

        return 0;
}

/*
 * compute NI group address, based on the current hostname setting.
 * see draft-ietf-ipngwg-icmp-name-lookup-* (04 and later).
 *
 * when ifp == NULL, the caller is responsible for filling scopeid.
 */
int
in6_nigroup(
        struct ifnet *ifp,
        const char *name,
        int namelen,
        struct in6_addr *in6)
{
        const char *p;
        u_char *q;
        MD5_CTX ctxt;
        u_int8_t digest[16];
        char l;
        char n[64];     /* a single label must not exceed 63 chars */

        if (!namelen || !name)
                return -1;

        p = name;
        while (p && *p && *p != '.' && p - name < namelen)
                p++;
        if (p - name > sizeof(n) - 1)
                return -1;      /* label too long */
        l = p - name;
        strncpy(n, name, l);
        n[(int)l] = '\0';
        for (q = (u_char *) n; *q; q++) {
                if ('A' <= *q && *q <= 'Z')
                        *q = *q - 'A' + 'a';
        }

        /* generate 8 bytes of pseudo-random value. */
        bzero(&ctxt, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, &l, sizeof(l));
        MD5Update(&ctxt, n, l);
        MD5Final(digest, &ctxt);

        bzero(in6, sizeof(*in6));
        in6->s6_addr16[0] = htons(0xff02);
        if (ifp)
                in6->s6_addr16[1] = htons(ifp->if_index);
        in6->s6_addr8[11] = 2;
        bcopy(digest, &in6->s6_addr32[3], sizeof(in6->s6_addr32[3]));

        return 0;
}

void
in6_nigroup_attach(
        const char *name,
        int namelen)
{
        struct ifnet *ifp;
        struct sockaddr_in6 mltaddr;
        struct in6_multi *in6m;
        int error;

        bzero(&mltaddr, sizeof(mltaddr));
        mltaddr.sin6_family = AF_INET6;
        mltaddr.sin6_len = sizeof(struct sockaddr_in6);
        if (in6_nigroup(NULL, name, namelen, &mltaddr.sin6_addr) != 0)
                return;

        ifnet_head_lock_shared();
        TAILQ_FOREACH(ifp, &ifnet_head, if_list) {
                mltaddr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
                ifnet_lock_shared(ifp);
                IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                ifnet_lock_done(ifp);
                if (!in6m) {
                        if (!in6_addmulti(&mltaddr.sin6_addr, ifp, &error, 0)) {
                                nd6log((LOG_ERR, "%s: failed to join %s "
                                    "(errno=%d)\n", if_name(ifp),
                                    ip6_sprintf(&mltaddr.sin6_addr), 
                                    error));
                        }
                }
        }
        ifnet_head_done();
}

void
in6_nigroup_detach(
        const char *name,
        int namelen)
{
        struct ifnet *ifp;
        struct sockaddr_in6 mltaddr;
        struct in6_multi *in6m;

        bzero(&mltaddr, sizeof(mltaddr));
        mltaddr.sin6_family = AF_INET6;
        mltaddr.sin6_len = sizeof(struct sockaddr_in6);
        if (in6_nigroup(NULL, name, namelen, &mltaddr.sin6_addr) != 0)
                return;

        ifnet_head_lock_shared();
        TAILQ_FOREACH(ifp, &ifnet_head, if_list) {
                mltaddr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
                ifnet_lock_shared(ifp);
                IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
                ifnet_lock_done(ifp);
                if (in6m)
                        in6_delmulti(in6m, 0);
        }
        ifnet_head_done();
}

/*
 * XXX multiple loopback interface needs more care.  for instance,
 * nodelocal address needs to be configured onto only one of them.
 * XXX multiple link-local address case
 */
int
in6_ifattach(
        struct ifnet *ifp,
        struct ifnet *altifp,   /* secondary EUI64 source */
        struct  in6_aliasreq *ifra)
{
        static size_t if_indexlim = 8;
        struct in6_ifaddr *ia;
        int error;

        /*
         * We have some arrays that should be indexed by if_index.
         * since if_index will grow dynamically, they should grow too.
         *      struct in6_ifstat **in6_ifstat
         *      struct icmp6_ifstat **icmp6_ifstat
         */
        if (in6_ifstat == NULL || icmp6_ifstat == NULL ||
            if_index >= if_indexlim) {
                while (if_index >= if_indexlim)
                        if_indexlim <<= 1;
        }
    
        lck_mtx_lock(ip6_mutex);
        /* grow in6_ifstat */
        if (in6_ifstatmax < if_indexlim) {
                size_t n;
                caddr_t q;
        
                n = if_indexlim * sizeof(struct in6_ifstat *);
                q = (caddr_t)_MALLOC(n, M_IFADDR, M_WAITOK);
                if (q == NULL) {
                        lck_mtx_unlock(ip6_mutex);
                        return ENOBUFS;
                }
                bzero(q, n);
                if (in6_ifstat) {
                        bcopy((caddr_t)in6_ifstat, q,
                                in6_ifstatmax * sizeof(struct in6_ifstat *));
                        FREE((caddr_t)in6_ifstat, M_IFADDR);
                }
                in6_ifstat = (struct in6_ifstat **)q;
                in6_ifstatmax = if_indexlim;
        }
    
        if (in6_ifstat[ifp->if_index] == NULL) {
                in6_ifstat[ifp->if_index] = (struct in6_ifstat *)
                        _MALLOC(sizeof(struct in6_ifstat), M_IFADDR, M_WAITOK);
                if (in6_ifstat[ifp->if_index] == NULL) {
                        lck_mtx_unlock(ip6_mutex);
                        return ENOBUFS;
                }
                bzero(in6_ifstat[ifp->if_index], sizeof(struct in6_ifstat));
        }
        lck_mtx_unlock(ip6_mutex);

        /* grow icmp6_ifstat, use inet6_domain_mutex as that is used in 
         * icmp6 routines 
         */
        lck_mtx_lock(inet6_domain_mutex);
        if (icmp6_ifstatmax < if_indexlim) {
                size_t n;
                caddr_t q;
        
                n = if_indexlim * sizeof(struct icmp6_ifstat *);
                q = (caddr_t)_MALLOC(n, M_IFADDR, M_WAITOK);
                if (q == NULL) {
                        lck_mtx_unlock(inet6_domain_mutex);
                        return ENOBUFS;
                }
                bzero(q, n);
                if (icmp6_ifstat) {
                        bcopy((caddr_t)icmp6_ifstat, q,
                                icmp6_ifstatmax * sizeof(struct icmp6_ifstat *));
                        FREE((caddr_t)icmp6_ifstat, M_IFADDR);
                }
                icmp6_ifstat = (struct icmp6_ifstat **)q;
                icmp6_ifstatmax = if_indexlim;
        }

        if (icmp6_ifstat[ifp->if_index] == NULL) {
                icmp6_ifstat[ifp->if_index] = (struct icmp6_ifstat *)
                        _MALLOC(sizeof(struct icmp6_ifstat), M_IFADDR, M_WAITOK);
                if (icmp6_ifstat[ifp->if_index] == NULL) {
                        lck_mtx_unlock(inet6_domain_mutex);
                        return ENOBUFS;
                }
                bzero(icmp6_ifstat[ifp->if_index], sizeof(struct icmp6_ifstat));
        }
        lck_mtx_unlock(inet6_domain_mutex);

        /* initialize NDP variables */
        if ((error = nd6_ifattach(ifp)) != 0)
                return error;

        /* initialize scope identifiers */
        if ((error = scope6_ifattach(ifp)) != 0)
                return error;

        /*
         * quirks based on interface type
         */
        switch (ifp->if_type) {
#if IFT_STF
        case IFT_STF:
                /*
                 * 6to4 interface is a very special kind of beast.
                 * no multicast, no linklocal.  RFC2529 specifies how to make
                 * linklocals for 6to4 interface, but there's no use and
                 * it is rather harmful to have one.
                 */
                goto statinit;
#endif
        default:
                break;
        }

        /*
         * usually, we require multicast capability to the interface
         */
        if ((ifp->if_flags & IFF_MULTICAST) == 0) {
                log(LOG_INFO, "in6_ifattach: "
                    "%s is not multicast capable, IPv6 not enabled\n",
                    if_name(ifp));
                return EINVAL;
        }

        /*
         * assign loopback address for loopback interface.
         * XXX multiple loopback interface case.
         */
        if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                if (in6_ifattach_loopback(ifp) != 0)
                        printf("in6_ifattach: in6_ifattach_loopback failed\n");
        }

        /*
         * assign a link-local address, if there's none. 
         */
        if (ip6_auto_linklocal) {
                ia = in6ifa_ifpforlinklocal(ifp, 0);
                if (ia == NULL) {
                        if (in6_ifattach_linklocal(ifp, altifp, ifra) == 0) {
                                /* linklocal address assigned */
                        } else {
                                log(LOG_INFO, "in6_ifattach: %s failed to "
                                    "attach a linklocal address.\n",
                                    if_name(ifp));
                                /* failed to assign linklocal address. bark? */
                        }
                } else {
                        ifafree(&ia->ia_ifa);
                }
        }

#if IFT_STF                     /* XXX */
statinit:       
#endif

        /* update dynamically. */
        if (in6_maxmtu < ifp->if_mtu)
                in6_maxmtu = ifp->if_mtu;

    return 0;
}

/*
 * NOTE: in6_ifdetach() does not support loopback if at this moment.
 * We don't need this function in bsdi, because interfaces are never removed
 * from the ifnet list in bsdi.
 */
void
in6_ifdetach(
        struct ifnet *ifp)
{
        struct in6_ifaddr *ia, *oia, *nia;
        struct ifaddr *ifa, *next;
        struct rtentry *rt;
        struct sockaddr_in6 sin6;

        /* nuke prefix list.  this may try to remove some of ifaddrs as well */
        in6_purgeprefix(ifp);

        /* remove neighbor management table */
        nd6_purge(ifp);

        /* nuke any of IPv6 addresses we have */
        
        lck_mtx_lock(nd6_mutex);
        for (ia = in6_ifaddrs; ia != NULL; ia = nia) {
                nia = ia->ia_next;
                if (ia->ia_ifa.ifa_ifp != ifp)
                        continue;
                in6_purgeaddr(&ia->ia_ifa, 1);
        }
        lck_mtx_unlock(nd6_mutex);

        ifnet_lock_exclusive(ifp);

        /* undo everything done by in6_ifattach(), just in case */
        for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = next)
        {
                next = ifa->ifa_list.tqe_next;


                if (ifa->ifa_addr->sa_family != AF_INET6
                 || !IN6_IS_ADDR_LINKLOCAL(&satosin6(&ifa->ifa_addr)->sin6_addr)) {
                        continue;
                }

                ia = (struct in6_ifaddr *)ifa;

                /* remove from the routing table */
                if ((ia->ia_flags & IFA_ROUTE) &&
                    (rt = rtalloc1((struct sockaddr *)&ia->ia_addr, 0, 0))) {
                        (void) rtrequest(RTM_DELETE,
                                (struct sockaddr *)&ia->ia_addr,
                                (struct sockaddr *)&ia->ia_addr,
                                (struct sockaddr *)&ia->ia_prefixmask,
                                rt->rt_flags, (struct rtentry **)0);
                        rtfree(rt);
                }

                /* remove from the linked list */
                if_detach_ifa(ifp, &ia->ia_ifa);

                /* also remove from the IPv6 address chain(itojun&jinmei) */
                oia = ia;
                lck_mtx_lock(nd6_mutex);
                if (oia == (ia = in6_ifaddrs))
                        in6_ifaddrs = 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 {
                                nd6log((LOG_ERR, 
                                    "%s: didn't unlink in6ifaddr from "
                                    "list\n", if_name(ifp)));
                        }
                }
                lck_mtx_unlock(nd6_mutex);

                ifafree(&oia->ia_ifa);
        }
        ifnet_lock_done(ifp);

        /*
         * remove neighbor management table.  we call it twice just to make
         * sure we nuke everything.  maybe we need just one call.
         * XXX: since the first call did not release addresses, some prefixes
         * might remain.  We should call nd6_purge() again to release the
         * prefixes after removing all addresses above.
         * (Or can we just delay calling nd6_purge until at this point?)
         */
        nd6_purge(ifp);

        /* remove route to link-local allnodes multicast (ff02::1) */
        bzero(&sin6, sizeof(sin6));
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_family = AF_INET6;
        sin6.sin6_addr = in6addr_linklocal_allnodes;
        sin6.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
        rt = rtalloc1((struct sockaddr *)&sin6, 0, 0);
        if (rt != NULL) {
                RT_LOCK(rt);
                if (rt->rt_ifp == ifp) {
                        /*
                         * Prevent another thread from modifying rt_key,
                         * rt_gateway via rt_setgate() after the rt_lock
                         * is dropped by marking the route as defunct.
                         */
                        rt->rt_flags |= RTF_CONDEMNED;
                        RT_UNLOCK(rt);
                        (void) rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                            rt_mask(rt), rt->rt_flags, 0);
                } else {
                        RT_UNLOCK(rt);
                }
                rtfree(rt);
        }
}

void
in6_get_tmpifid(
        struct ifnet *ifp,
        u_int8_t *retbuf,
        const u_int8_t *baseid,
        int generate)
{
        u_int8_t nullbuf[8];
        struct nd_ifinfo *ndi;

        lck_rw_lock_shared(nd_if_rwlock);
        ndi = &nd_ifinfo[ifp->if_index];
        bzero(nullbuf, sizeof(nullbuf));
        if (bcmp(ndi->randomid, nullbuf, sizeof(nullbuf)) == 0) {
                /* we've never created a random ID.  Create a new one. */
                generate = 1;
        }

        if (generate) {
                bcopy(baseid, ndi->randomseed1, sizeof(ndi->randomseed1));

                /* generate_tmp_ifid will update seedn and buf */
                (void)generate_tmp_ifid(ndi->randomseed0, ndi->randomseed1,
                                        ndi->randomid);
        }
        bcopy(ndi->randomid, retbuf, 8);
        lck_rw_done(nd_if_rwlock);
}

void
in6_tmpaddrtimer(
        __unused void *ignored_arg)
{
        int i;
        struct nd_ifinfo *ndi;
        u_int8_t nullbuf[8];

        timeout(in6_tmpaddrtimer, (caddr_t)0,
                      (ip6_temp_preferred_lifetime - ip6_desync_factor -
                       ip6_temp_regen_advance) * hz);

        if (ip6_use_tempaddr) {
                lck_rw_lock_shared(nd_if_rwlock);
                bzero(nullbuf, sizeof(nullbuf));
                for (i = 1; i < nd_ifinfo_indexlim + 1; i++) {
                        ndi = &nd_ifinfo[i];
                        if (ndi->flags != ND6_IFF_PERFORMNUD)
                                continue;
                        if (bcmp(ndi->randomid, nullbuf, sizeof(nullbuf)) != 0) {
                                /*
                                 * We've been generating a random ID on this interface.
                                 * Create a new one.
                                 */
                                (void)generate_tmp_ifid(ndi->randomseed0,
                                                        ndi->randomseed1,
                                                        ndi->randomid);
                        }
                }
                lck_rw_done(nd_if_rwlock);
        }
}