xnu-2050.7.9.tar.gz

[apple/xnu.git] / bsd / netinet6 / icmp6.c

/*
 * Copyright (c) 2000-2012 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
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*      $FreeBSD: src/sys/netinet6/icmp6.c,v 1.6.2.6 2001/07/10 09:44:16 ume Exp $      */
/*      $KAME: icmp6.c,v 1.211 2001/04/04 05:56:20 itojun Exp $ */

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

/*
 * Copyright (c) 1982, 1986, 1988, 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.
 *
 *      @(#)ip_icmp.c   8.2 (Berkeley) 1/4/94
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mcache.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/domain.h>
#include <sys/kauth.h>

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

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/mld6_var.h>
#include <netinet/in_pcb.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/ip6protosw.h>
#include <netinet6/scope6_var.h>

#if IPSEC
#include <netinet6/ipsec.h>
#include <netkey/key.h>

extern int ipsec_bypass;
#endif

#include <net/net_osdep.h>

extern struct domain inet6domain;
extern struct ip6protosw inet6sw[];
extern struct ip6protosw *ip6_protox[];

extern uint32_t rip_sendspace;
extern uint32_t rip_recvspace;

struct icmp6stat icmp6stat;

extern struct inpcbhead ripcb;
extern int icmp6errppslim;
static int icmp6errpps_count = 0;
static struct timeval icmp6errppslim_last;
extern int icmp6_nodeinfo;
extern struct inpcbinfo ripcbinfo;
extern lck_mtx_t *inet6_domain_mutex;

static void icmp6_errcount(struct icmp6errstat *, int, int);
static int icmp6_rip6_input(struct mbuf **, int);
static int icmp6_ratelimit(const struct in6_addr *, const int, const int);
static const char *icmp6_redirect_diag(struct in6_addr *,
        struct in6_addr *, struct in6_addr *);
#ifndef HAVE_PPSRATECHECK
static int ppsratecheck(struct timeval *, int *, int);
#endif
static struct mbuf *ni6_input(struct mbuf *, int);
static struct mbuf *ni6_nametodns(const char *, int, int);
static int ni6_dnsmatch(const char *, int, const char *, int);
static int ni6_addrs(struct icmp6_nodeinfo *, 
                          struct ifnet **, char *);
static int ni6_store_addrs(struct icmp6_nodeinfo *, struct icmp6_nodeinfo *,
                                struct ifnet *, int);
static int icmp6_notify_error(struct mbuf *, int, int, int);



void
icmp6_init()
{
        mld_init();
}

static void
icmp6_errcount(stat, type, code)
        struct icmp6errstat *stat;
        int type, code;
{
        switch (type) {
        case ICMP6_DST_UNREACH:
                switch (code) {
                case ICMP6_DST_UNREACH_NOROUTE:
                        stat->icp6errs_dst_unreach_noroute++;
                        return;
                case ICMP6_DST_UNREACH_ADMIN:
                        stat->icp6errs_dst_unreach_admin++;
                        return;
                case ICMP6_DST_UNREACH_BEYONDSCOPE:
                        stat->icp6errs_dst_unreach_beyondscope++;
                        return;
                case ICMP6_DST_UNREACH_ADDR:
                        stat->icp6errs_dst_unreach_addr++;
                        return;
                case ICMP6_DST_UNREACH_NOPORT:
                        stat->icp6errs_dst_unreach_noport++;
                        return;
                }
                break;
        case ICMP6_PACKET_TOO_BIG:
                stat->icp6errs_packet_too_big++;
                return;
        case ICMP6_TIME_EXCEEDED:
                switch (code) {
                case ICMP6_TIME_EXCEED_TRANSIT:
                        stat->icp6errs_time_exceed_transit++;
                        return;
                case ICMP6_TIME_EXCEED_REASSEMBLY:
                        stat->icp6errs_time_exceed_reassembly++;
                        return;
                }
                break;
        case ICMP6_PARAM_PROB:
                switch (code) {
                case ICMP6_PARAMPROB_HEADER:
                        stat->icp6errs_paramprob_header++;
                        return;
                case ICMP6_PARAMPROB_NEXTHEADER:
                        stat->icp6errs_paramprob_nextheader++;
                        return;
                case ICMP6_PARAMPROB_OPTION:
                        stat->icp6errs_paramprob_option++;
                        return;
                }
                break;
        case ND_REDIRECT:
                stat->icp6errs_redirect++;
                return;
        }
        stat->icp6errs_unknown++;
}

/*
 * A wrapper function for icmp6_error() necessary when the erroneous packet
 * may not contain enough scope zone information.
 */
void
icmp6_error2(struct mbuf *m, int type, int code, int param,
    struct ifnet *ifp)
{
        struct ip6_hdr *ip6;

        if (ifp == NULL)
                return;

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr),return );
#else
        if (m->m_len < sizeof(struct ip6_hdr)) {
                m = m_pullup(m, sizeof(struct ip6_hdr));
                if (m == NULL)
                        return;
        }
#endif

        ip6 = mtod(m, struct ip6_hdr *);

        if (in6_setscope(&ip6->ip6_src, ifp, NULL) != 0)
                return;
        if (in6_setscope(&ip6->ip6_dst, ifp, NULL) != 0)
                return;

        icmp6_error(m, type, code, param);
}

/*
 * Generate an error packet of type error in response to bad IP6 packet.
 */
void
icmp6_error(struct mbuf *m, int type, int code, int param)
{
        struct ip6_hdr *oip6, *nip6;
        struct icmp6_hdr *icmp6;
        u_int preplen;
        int off;
        int nxt;

        icmp6stat.icp6s_error++;

        /* count per-type-code statistics */
        icmp6_errcount(&icmp6stat.icp6s_outerrhist, type, code);

#ifdef M_DECRYPTED      /*not openbsd*/
        if (m->m_flags & M_DECRYPTED) {
                icmp6stat.icp6s_canterror++;
                goto freeit;
        }
#endif

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), return);
#else
        if (m->m_len < sizeof(struct ip6_hdr)) {
                m = m_pullup(m, sizeof(struct ip6_hdr));
                if (m == NULL)
                        return;
        }
#endif
        oip6 = mtod(m, struct ip6_hdr *);

        /*
         * If the destination address of the erroneous packet is a multicast
         * address, or the packet was sent using link-layer multicast,
         * we should basically suppress sending an error (RFC 2463, Section
         * 2.4).
         * We have two exceptions (the item e.2 in that section):
         * - the Pakcet Too Big message can be sent for path MTU discovery.
         * - the Parameter Problem Message that can be allowed an icmp6 error
         *   in the option type field.  This check has been done in
         *   ip6_unknown_opt(), so we can just check the type and code.
         */
        if ((m->m_flags & (M_BCAST|M_MCAST) ||
             IN6_IS_ADDR_MULTICAST(&oip6->ip6_dst)) &&
            (type != ICMP6_PACKET_TOO_BIG &&
             (type != ICMP6_PARAM_PROB ||
              code != ICMP6_PARAMPROB_OPTION)))
                goto freeit;

        /*
         * RFC 2463, 2.4 (e.5): source address check.
         * XXX: the case of anycast source?
         */
        if (IN6_IS_ADDR_UNSPECIFIED(&oip6->ip6_src) ||
            IN6_IS_ADDR_MULTICAST(&oip6->ip6_src))
                goto freeit;

        /*
         * If we are about to send ICMPv6 against ICMPv6 error/redirect,
         * don't do it.
         */
        nxt = -1;
        off = ip6_lasthdr(m, 0, IPPROTO_IPV6, &nxt);
        if (off >= 0 && nxt == IPPROTO_ICMPV6) {
                struct icmp6_hdr *icp;

#ifndef PULLDOWN_TEST
                IP6_EXTHDR_CHECK(m, 0, off + sizeof(struct icmp6_hdr), return);
                icp = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
#else
                IP6_EXTHDR_GET(icp, struct icmp6_hdr *, m, off,
                        sizeof(*icp));
                if (icp == NULL) {
                        icmp6stat.icp6s_tooshort++;
                        return;
                }
#endif
                if (icp->icmp6_type < ICMP6_ECHO_REQUEST ||
                    icp->icmp6_type == ND_REDIRECT) {
                        /*
                         * ICMPv6 error
                         * Special case: for redirect (which is
                         * informational) we must not send icmp6 error.
                         */
                        icmp6stat.icp6s_canterror++;
                        goto freeit;
                } else {
                        /* ICMPv6 informational - send the error */
                }
        } else {
                /* non-ICMPv6 - send the error */
        }

        oip6 = mtod(m, struct ip6_hdr *); /* adjust pointer */

        /* Finally, do rate limitation check. */
        if (icmp6_ratelimit(&oip6->ip6_src, type, code)) {
                icmp6stat.icp6s_toofreq++;
                goto freeit;
        }

        /*
         * OK, ICMP6 can be generated.
         */

        if (m->m_pkthdr.len >= ICMPV6_PLD_MAXLEN)
                m_adj(m, ICMPV6_PLD_MAXLEN - m->m_pkthdr.len);

        preplen = sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr);
        M_PREPEND(m, preplen, M_DONTWAIT);
        if (m && m->m_len < preplen)
                m = m_pullup(m, preplen);
        if (m == NULL) {
                nd6log((LOG_DEBUG, "ENOBUFS in icmp6_error %d\n", __LINE__));
                return;
        }

        nip6 = mtod(m, struct ip6_hdr *);
        nip6->ip6_src  = oip6->ip6_src;
        nip6->ip6_dst  = oip6->ip6_dst;

        in6_clearscope(&oip6->ip6_src);
        in6_clearscope(&oip6->ip6_dst);

        icmp6 = (struct icmp6_hdr *)(nip6 + 1);
        icmp6->icmp6_type = type;
        icmp6->icmp6_code = code;
        icmp6->icmp6_pptr = htonl((u_int32_t)param);

        /*
         * icmp6_reflect() is designed to be in the input path.
         * icmp6_error() can be called from both input and output path,
         * and if we are in output path rcvif could contain bogus value.
         * clear m->m_pkthdr.rcvif for safety, we should have enough scope
         * information in ip header (nip6).
         */
        m->m_pkthdr.rcvif = NULL;

        icmp6stat.icp6s_outhist[type]++;
        icmp6_reflect(m, sizeof(struct ip6_hdr)); /* header order: IPv6 - ICMPv6 */

        return;

  freeit:
        /*
         * If we can't tell whether or not we can generate ICMP6, free it.
         */
        m_freem(m);
}

/*
 * Process a received ICMP6 message.
 */
int
icmp6_input(struct mbuf **mp, int *offp, int proto)
{
#pragma unused(proto)
        struct mbuf *m = *mp, *n;
        struct ifnet *ifp;
        struct ip6_hdr *ip6, *nip6;
        struct icmp6_hdr *icmp6, *nicmp6;
        int off = *offp;
        int icmp6len = m->m_pkthdr.len - *offp;
        int code, sum, noff, proxy = 0;

        ifp = m->m_pkthdr.rcvif;

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, sizeof(struct icmp6_hdr), return IPPROTO_DONE);
        /* m might change if M_LOOP.  So, call mtod after this */
#endif

        /* Expect 32-bit aligned data pointer on strict-align platforms */
        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

        /*
         * Locate icmp6 structure in mbuf, and check
         * that not corrupted and of at least minimum length
         */
        ip6 = mtod(m, struct ip6_hdr *);
        if (icmp6len < sizeof(struct icmp6_hdr)) {
                icmp6stat.icp6s_tooshort++;
                goto freeit;
        }

        /*
         * Check multicast group membership.
         * Note: SSM filters are not applied for ICMPv6 traffic.
         */
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                struct in6_multi        *inm;

                in6_multihead_lock_shared();
                IN6_LOOKUP_MULTI(&ip6->ip6_dst, ifp, inm);
                in6_multihead_lock_done();

                if (inm == NULL) {
                        /*
                         * Don't discard if this is a Neighbor Solicitation
                         * that needs to be proxied (see check down below.)
                         */
                        if (!(m->m_pkthdr.aux_flags & MAUXF_PROXY_DST)) {
                                ip6stat.ip6s_notmember++;
                                in6_ifstat_inc(m->m_pkthdr.rcvif,
                                    ifs6_in_discard);
                                goto freeit;
                        }
                } else {
                        IN6M_REMREF(inm);
                }
        }

        /*
         * calculate the checksum
         */
#ifndef PULLDOWN_TEST
        icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
#else
        IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off, sizeof(*icmp6));
        if (icmp6 == NULL) {
                icmp6stat.icp6s_tooshort++;
                return IPPROTO_DONE;
        }
#endif
        code = icmp6->icmp6_code;

        if ((sum = in6_cksum(m, IPPROTO_ICMPV6, off, icmp6len)) != 0) {
                nd6log((LOG_ERR,
                    "ICMP6 checksum error(%d|%x) %s\n",
                    icmp6->icmp6_type, sum, ip6_sprintf(&ip6->ip6_src)));
                icmp6stat.icp6s_checksum++;
                goto freeit;
        }

        if (m->m_pkthdr.aux_flags & MAUXF_PROXY_DST) {
                /*
                 * This is the special case of proxying NS (dst is either
                 * solicited-node multicast or unicast); process it locally
                 * but don't deliver it to sockets.  It practically lets us
                 * steer the packet to nd6_prproxy_ns_input, where more
                 * specific tests and actions will be taken.
                 */
                switch (icmp6->icmp6_type) {
                case ND_NEIGHBOR_SOLICIT:
                        proxy = 1;
                        break;
                default:
                        goto freeit;
                }
        }

        icmp6stat.icp6s_inhist[icmp6->icmp6_type]++;
        icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_msg);
        if (icmp6->icmp6_type < ICMP6_INFOMSG_MASK)
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_error);

        switch (icmp6->icmp6_type) {
        case ICMP6_DST_UNREACH:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_dstunreach);
                switch (code) {
                case ICMP6_DST_UNREACH_NOROUTE:
                        code = PRC_UNREACH_NET;
                        break;
                case ICMP6_DST_UNREACH_ADMIN:
                        icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_adminprohib);
                        code = PRC_UNREACH_PROTOCOL; /* is this a good code? */
                        break;
                case ICMP6_DST_UNREACH_ADDR:
                        code = PRC_HOSTDEAD;
                        break;
                case ICMP6_DST_UNREACH_BEYONDSCOPE:
                        /* I mean "source address was incorrect." */
                        code = PRC_PARAMPROB;
                        break;
                case ICMP6_DST_UNREACH_NOPORT:
                        code = PRC_UNREACH_PORT;
                        break;
                default:
                        goto badcode;
                }
                goto deliver;
                break;

        case ICMP6_PACKET_TOO_BIG:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_pkttoobig);

                code = PRC_MSGSIZE;

                /*
                 * Updating the path MTU will be done after examining
                 * intermediate extension headers.
                 */
                goto deliver;
                break;

        case ICMP6_TIME_EXCEEDED:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_timeexceed);
                switch (code) {
                case ICMP6_TIME_EXCEED_TRANSIT:
                        code = PRC_TIMXCEED_INTRANS;
                        break;
                case ICMP6_TIME_EXCEED_REASSEMBLY:
                        code = PRC_TIMXCEED_REASS;
                        break;
                default:
                        goto badcode;
                }
                goto deliver;
                break;

        case ICMP6_PARAM_PROB:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_paramprob);
                switch (code) {
                case ICMP6_PARAMPROB_NEXTHEADER:
                        code = PRC_UNREACH_PROTOCOL;
                        break;
                case ICMP6_PARAMPROB_HEADER:
                case ICMP6_PARAMPROB_OPTION:
                        code = PRC_PARAMPROB;
                        break;
                default:
                        goto badcode;
                }
                goto deliver;
                break;

        case ICMP6_ECHO_REQUEST:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_echo);
                if (code != 0)
                        goto badcode;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copy(m, 0, M_COPYALL)) == NULL) {
                        /* Give up remote */
                        goto rate_limit_checked;
                        break;
                }
                if ((n->m_flags & M_EXT) != 0
                 || n->m_len < off + sizeof(struct icmp6_hdr)) {
                        struct mbuf *n0 = n;
                        const int maxlen = sizeof(*nip6) + sizeof(*nicmp6);

                        /*
                         * Prepare an internal mbuf. m_pullup() doesn't
                         * always copy the length we specified.
                         */
                        if (maxlen >= MCLBYTES) {
                                /* Give up remote */
                                m_freem(n0);
                                goto rate_limit_checked;
                                break;
                        }
                        MGETHDR(n, M_DONTWAIT, n0->m_type);     /* MAC-OK */
                        if (n && maxlen >= MHLEN) {
                                MCLGET(n, M_DONTWAIT);
                                if ((n->m_flags & M_EXT) == 0) {
                                        m_free(n);
                                        n = NULL;
                                }
                        }
                        if (n == NULL) {
                                /* Give up remote */
                                m_freem(n0);
                                goto rate_limit_checked;
                                break;
                        }
                        M_COPY_PKTHDR(n, n0);
                        /*
                         * Copy IPv6 and ICMPv6 only.
                         */
                        nip6 = mtod(n, struct ip6_hdr *);
                        bcopy(ip6, nip6, sizeof(struct ip6_hdr));
                        nicmp6 = (struct icmp6_hdr *)(nip6 + 1);
                        bcopy(icmp6, nicmp6, sizeof(struct icmp6_hdr));
                        noff = sizeof(struct ip6_hdr);
                        n->m_pkthdr.len = n->m_len =
                                noff + sizeof(struct icmp6_hdr);
                        /*
                         * Adjust mbuf. ip6_plen will be adjusted in
                         * ip6_output().
                         */
                        m_adj(n0, off + sizeof(struct icmp6_hdr));
                        n->m_pkthdr.len += n0->m_pkthdr.len;
                        n->m_next = n0;
                        n0->m_flags &= ~M_PKTHDR;
                } else {
                        nip6 = mtod(n, struct ip6_hdr *);
                        IP6_EXTHDR_GET(nicmp6, struct icmp6_hdr *, n, off,
                                sizeof(*nicmp6));
                        noff = off;
                }
                if(nicmp6 == NULL)
                        panic("nicmp6 is NULL in %s, which isn't good!\n", __FUNCTION__);
                else {
                        nicmp6->icmp6_type = ICMP6_ECHO_REPLY;
                        nicmp6->icmp6_code = 0;
                }
                if (n) {
                        icmp6stat.icp6s_reflect++;
                        icmp6stat.icp6s_outhist[ICMP6_ECHO_REPLY]++;
                        icmp6_reflect(n, noff);
                }
                goto rate_limit_checked;
                break;

        case ICMP6_ECHO_REPLY:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_echoreply);
                if (code != 0)
                        goto badcode;
                break;

        case MLD_LISTENER_QUERY:
        case MLD_LISTENER_REPORT:

                if (icmp6len < sizeof(struct mld_hdr))
                        goto badlen;
                if (icmp6->icmp6_type == MLD_LISTENER_QUERY) /* XXX: ugly... */
                        icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mldquery);
                else
                        icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mldreport);

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        if (mld_input(m, off, icmp6len) == IPPROTO_DONE)
                                m = NULL;
                        goto freeit;
                }
                if (mld_input(n, off, icmp6len) != IPPROTO_DONE)
                        m_freem(n);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case MLD_LISTENER_DONE:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mlddone);
                if (icmp6len < sizeof(struct mld_hdr))  /* necessary? */
                        goto badlen;
                break;          /* nothing to be done in kernel */

        case MLD_MTRACE_RESP:
        case MLD_MTRACE:
                /* XXX: these two are experimental.  not officially defined. */
                /* XXX: per-interface statistics? */
                break;          /* just pass it to applications */

        case ICMP6_NI_QUERY:
                if (!icmp6_nodeinfo)
                        break;
//### LD 10/20 Check fbsd differences here. Not sure we're more advanced or not.
                /* By RFC 4620 refuse to answer queries from global scope addresses */ 
                if ((icmp6_nodeinfo & 8) != 8 && in6_addrscope(&ip6->ip6_src) == IPV6_ADDR_SCOPE_GLOBAL)
                        break;

                if (icmp6len < sizeof(struct icmp6_nodeinfo))
                        goto badlen;

#ifndef PULLDOWN_TEST
                IP6_EXTHDR_CHECK(m, off, sizeof(struct icmp6_nodeinfo),
                                 return IPPROTO_DONE);
#endif
                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                n = m_copy(m, 0, M_COPYALL);
                if (n)
                        n = ni6_input(n, off);
                if (n) {
                        noff = sizeof(struct ip6_hdr);
                        icmp6stat.icp6s_reflect++;
                        icmp6stat.icp6s_outhist[ICMP6_WRUREPLY]++;
                        icmp6_reflect(n, noff);
                }
                goto rate_limit_checked;
                break;

        case ICMP6_WRUREPLY:
                if (code != 0)
                        goto badcode;
                break;

        case ND_ROUTER_SOLICIT:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_routersolicit);
                if (code != 0)
                        goto badcode;
                if (icmp6len < sizeof(struct nd_router_solicit))
                        goto badlen;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        nd6_rs_input(m, off, icmp6len);
                        m = NULL;
                        goto freeit;
                }
                nd6_rs_input(n, off, icmp6len);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case ND_ROUTER_ADVERT:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_routeradvert);
                if (code != 0)
                        goto badcode;
                if (icmp6len < sizeof(struct nd_router_advert))
                        goto badlen;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        nd6_ra_input(m, off, icmp6len);
                        m = NULL;
                        goto freeit;
                }
                nd6_ra_input(n, off, icmp6len);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case ND_NEIGHBOR_SOLICIT:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_neighborsolicit);
                if (code != 0)
                        goto badcode;
                if (icmp6len < sizeof(struct nd_neighbor_solicit))
                        goto badlen;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        nd6_ns_input(m, off, icmp6len);
                        m = NULL;
                        goto freeit;
                }
                nd6_ns_input(n, off, icmp6len);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case ND_NEIGHBOR_ADVERT:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_neighboradvert);
                if (code != 0)
                        goto badcode;
                if (icmp6len < sizeof(struct nd_neighbor_advert))
                        goto badlen;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        nd6_na_input(m, off, icmp6len);
                        m = NULL;
                        goto freeit;
                }
                nd6_na_input(n, off, icmp6len);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case ND_REDIRECT:
                icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_redirect);
                if (code != 0)
                        goto badcode;
                if (icmp6len < sizeof(struct nd_redirect))
                        goto badlen;

                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
                        /* give up local */
                        icmp6_redirect_input(m, off);
                        m = NULL;
                        goto freeit;
                }
                icmp6_redirect_input(n, off);
                /* m stays. */
                goto rate_limit_checked;
                break;

        case ICMP6_ROUTER_RENUMBERING:
                if (code != ICMP6_ROUTER_RENUMBERING_COMMAND &&
                    code != ICMP6_ROUTER_RENUMBERING_RESULT)
                        goto badcode;
                if (icmp6len < sizeof(struct icmp6_router_renum))
                        goto badlen;
                break;

        default:
                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                nd6log((LOG_DEBUG,
                    "icmp6_input: unknown type %d(src=%s, dst=%s, ifid=%d)\n",
                    icmp6->icmp6_type, ip6_sprintf(&ip6->ip6_src),
                    ip6_sprintf(&ip6->ip6_dst),
                    m->m_pkthdr.rcvif ? m->m_pkthdr.rcvif->if_index : 0));
                if (icmp6->icmp6_type < ICMP6_ECHO_REQUEST) {
                        /* ICMPv6 error: MUST deliver it by spec... */
                        code = PRC_NCMDS;
                        /* deliver */
                } else {
                        /* ICMPv6 informational: MUST not deliver */
                        goto rate_limit_checked;
                        break;
                }
        deliver:
                if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                        icmp6stat.icp6s_toofreq++;
                        goto freeit;
                }

                if (icmp6_notify_error(m, off, icmp6len, code)) {
                        /* In this case, m should've been freed. */
                        return(IPPROTO_DONE);
                }
                break;

        badcode:
                icmp6stat.icp6s_badcode++;
                break;

        badlen:
                icmp6stat.icp6s_badlen++;
                break;
        }

        if (icmp6_ratelimit(&ip6->ip6_dst, icmp6->icmp6_type, code)) {
                icmp6stat.icp6s_toofreq++;
                goto freeit;
        }
rate_limit_checked:
        /* deliver the packet to appropriate sockets (unless proxying) */
        if (!proxy) {
                icmp6_rip6_input(&m, *offp);
                return IPPROTO_DONE;
        }

freeit:
        m_freem(m);
        return IPPROTO_DONE;
}

static int
icmp6_notify_error(m, off, icmp6len, code)
        struct mbuf *m;
        int off, icmp6len, code;
{
        struct icmp6_hdr *icmp6;
        struct ip6_hdr *eip6;
        u_int32_t notifymtu;
        struct sockaddr_in6 icmp6src, icmp6dst;

        if (icmp6len < sizeof(struct icmp6_hdr) + sizeof(struct ip6_hdr)) {
                icmp6stat.icp6s_tooshort++;
                goto freeit;
        }
#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off,
                         sizeof(struct icmp6_hdr) + sizeof(struct ip6_hdr),
                         return -1);
        icmp6 = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
#else
        IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off,
                       sizeof(*icmp6) + sizeof(struct ip6_hdr));
        if (icmp6 == NULL) {
                icmp6stat.icp6s_tooshort++;
                return(-1);
        }
#endif
        eip6 = (struct ip6_hdr *)(icmp6 + 1);

        /* Detect the upper level protocol */
        {
                void (*ctlfunc)(int, struct sockaddr *, void *);
                u_int8_t nxt = eip6->ip6_nxt;
                int eoff = off + sizeof(struct icmp6_hdr) +
                        sizeof(struct ip6_hdr);
                struct ip6ctlparam ip6cp;
                struct in6_addr *finaldst = NULL;
                int icmp6type = icmp6->icmp6_type;
                struct ip6_frag *fh;
                struct ip6_rthdr *rth;
                struct ip6_rthdr0 *rth0;
                int rthlen;

                while (1) { /* XXX: should avoid infinite loop explicitly? */
                        struct ip6_ext *eh;

                        switch (nxt) {
                        case IPPROTO_HOPOPTS:
                        case IPPROTO_DSTOPTS:
                        case IPPROTO_AH:
#ifndef PULLDOWN_TEST
                                IP6_EXTHDR_CHECK(m, 0, eoff +
                                                 sizeof(struct ip6_ext),
                                                 return -1);
                                eh = (struct ip6_ext *)(mtod(m, caddr_t)
                                                        + eoff);
#else
                                IP6_EXTHDR_GET(eh, struct ip6_ext *, m,
                                               eoff, sizeof(*eh));
                                if (eh == NULL) {
                                        icmp6stat.icp6s_tooshort++;
                                        return(-1);
                                }
#endif

                                if (nxt == IPPROTO_AH)
                                        eoff += (eh->ip6e_len + 2) << 2;
                                else
                                        eoff += (eh->ip6e_len + 1) << 3;
                                nxt = eh->ip6e_nxt;
                                break;
                        case IPPROTO_ROUTING:
                                /*
                                 * When the erroneous packet contains a
                                 * routing header, we should examine the
                                 * header to determine the final destination.
                                 * Otherwise, we can't properly update
                                 * information that depends on the final
                                 * destination (e.g. path MTU).
                                 */
#ifndef PULLDOWN_TEST
                                IP6_EXTHDR_CHECK(m, 0, eoff + sizeof(*rth),
                                                 return -1);
                                rth = (struct ip6_rthdr *)(mtod(m, caddr_t)
                                                           + eoff);
#else
                                IP6_EXTHDR_GET(rth, struct ip6_rthdr *, m,
                                               eoff, sizeof(*rth));
                                if (rth == NULL) {
                                        icmp6stat.icp6s_tooshort++;
                                        return(-1);
                                }
#endif
                                rthlen = (rth->ip6r_len + 1) << 3;
                                /*
                                 * XXX: currently there is no
                                 * officially defined type other
                                 * than type-0.
                                 * Note that if the segment left field
                                 * is 0, all intermediate hops must
                                 * have been passed.
                                 */
                                if (rth->ip6r_segleft &&
                                    rth->ip6r_type == IPV6_RTHDR_TYPE_0) {
                                        int hops;

#ifndef PULLDOWN_TEST
                                        IP6_EXTHDR_CHECK(m, 0, eoff + rthlen,
                                                         return -1);
                                        rth0 = (struct ip6_rthdr0 *)(mtod(m, caddr_t) + eoff);
#else
                                        IP6_EXTHDR_GET(rth0,
                                                       struct ip6_rthdr0 *, m,
                                                       eoff, rthlen);
                                        if (rth0 == NULL) {
                                                icmp6stat.icp6s_tooshort++;
                                                return(-1);
                                        }
#endif
                                        /* just ignore a bogus header */
                                        if ((rth0->ip6r0_len % 2) == 0 &&
                                            (hops = rth0->ip6r0_len/2))
                                                finaldst = (struct in6_addr *)(void *)(rth0 + 1) + (hops - 1);
                                }
                                eoff += rthlen;
                                nxt = rth->ip6r_nxt;
                                break;
                        case IPPROTO_FRAGMENT:
#ifndef PULLDOWN_TEST
                                IP6_EXTHDR_CHECK(m, 0, eoff +
                                                 sizeof(struct ip6_frag),
                                                 return -1);
                                fh = (struct ip6_frag *)(mtod(m, caddr_t)
                                                         + eoff);
#else
                                IP6_EXTHDR_GET(fh, struct ip6_frag *, m,
                                               eoff, sizeof(*fh));
                                if (fh == NULL) {
                                        icmp6stat.icp6s_tooshort++;
                                        return (-1);
                                }
#endif
                                /*
                                 * Data after a fragment header is meaningless
                                 * unless it is the first fragment, but
                                 * we'll go to the notify label for path MTU
                                 * discovery.
                                 */
                                if (fh->ip6f_offlg & IP6F_OFF_MASK)
                                        goto notify;

                                eoff += sizeof(struct ip6_frag);
                                nxt = fh->ip6f_nxt;
                                break;
                        default:
                                /*
                                 * This case includes ESP and the No Next
                                 * Header.  In such cases going to the notify
                                 * label does not have any meaning
                                 * (i.e. ctlfunc will be NULL), but we go
                                 * anyway since we might have to update
                                 * path MTU information.
                                 */
                                goto notify;
                        }
                }
          notify:
#ifndef PULLDOWN_TEST
                icmp6 = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
#else
                IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off,
                    sizeof(*icmp6) + sizeof(struct ip6_hdr));
                if (icmp6 == NULL) {
                        icmp6stat.icp6s_tooshort++;
                        return (-1);
                }
#endif

                /*
                 * retrieve parameters from the inner IPv6 header, and convert
                 * them into sockaddr structures.
                 * XXX: there is no guarantee that the source or destination
                 * addresses of the inner packet are in the same scope as
                 * the addresses of the icmp packet.  But there is no other
                 * way to determine the zone.
                 */
                eip6 = (struct ip6_hdr *)(icmp6 + 1);

                bzero(&icmp6dst, sizeof(icmp6dst));
                icmp6dst.sin6_len = sizeof(struct sockaddr_in6);
                icmp6dst.sin6_family = AF_INET6;
                if (finaldst == NULL)
                        icmp6dst.sin6_addr = eip6->ip6_dst;
                else
                        icmp6dst.sin6_addr = *finaldst;
                if (in6_setscope(&icmp6dst.sin6_addr, m->m_pkthdr.rcvif, NULL))
                        goto freeit;
                bzero(&icmp6src, sizeof(icmp6src));
                icmp6src.sin6_len = sizeof(struct sockaddr_in6);
                icmp6src.sin6_family = AF_INET6;
                icmp6src.sin6_addr = eip6->ip6_src;
                if (in6_setscope(&icmp6src.sin6_addr, m->m_pkthdr.rcvif, NULL))
                        goto freeit;
                icmp6src.sin6_flowinfo =
                    (eip6->ip6_flow & IPV6_FLOWLABEL_MASK);

                if (finaldst == NULL)
                        finaldst = &eip6->ip6_dst;
                ip6cp.ip6c_m = m;
                ip6cp.ip6c_icmp6 = icmp6;
                ip6cp.ip6c_ip6 = (struct ip6_hdr *)(icmp6 + 1);
                ip6cp.ip6c_off = eoff;
                ip6cp.ip6c_finaldst = finaldst;
                ip6cp.ip6c_src = &icmp6src;
                ip6cp.ip6c_nxt = nxt;

                if (icmp6type == ICMP6_PACKET_TOO_BIG) {
                        notifymtu = ntohl(icmp6->icmp6_mtu);
                        ip6cp.ip6c_cmdarg = (void *)&notifymtu;
                        icmp6_mtudisc_update(&ip6cp, 1);        /*XXX*/
                }

                ctlfunc = (void (*)(int, struct sockaddr *, void *))
                        (ip6_protox[nxt]->pr_ctlinput);
                if (ctlfunc) {
                        (void) (*ctlfunc)(code, (struct sockaddr *)&icmp6dst,
                                          &ip6cp);
                }
        }
        return(0);

freeit:
        m_freem(m);
        return(-1);
}

void
icmp6_mtudisc_update(ip6cp, validated)
        struct ip6ctlparam *ip6cp;
        int validated;
{
        struct in6_addr *dst = ip6cp->ip6c_finaldst;
        struct icmp6_hdr *icmp6 = ip6cp->ip6c_icmp6;
        struct mbuf *m = ip6cp->ip6c_m; /* will be necessary for scope issue */
        u_int mtu = ntohl(icmp6->icmp6_mtu);
        struct rtentry *rt = NULL;
        struct sockaddr_in6 sin6;
        /*
         * we reject ICMPv6 too big with abnormally small value.
         * XXX what is the good definition of "abnormally small"?
         */
        if (mtu < sizeof(struct ip6_hdr) + sizeof(struct ip6_frag) + 8)
                return;

        if (!validated)
                return;

        /*
         * In case the suggested mtu is less than IPV6_MMTU, we
         * only need to remember that it was for above mentioned
         * "alwaysfrag" case.
         * Try to be as close to the spec as possible.
         */
        if (mtu < IPV6_MMTU)
                mtu = IPV6_MMTU - 8;

        bzero(&sin6, sizeof(sin6));
        sin6.sin6_family = PF_INET6;
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_addr = *dst;
        /* XXX normally, this won't happen */
        if (IN6_IS_ADDR_LINKLOCAL(dst)) {
                sin6.sin6_addr.s6_addr16[1] =
                    htons(m->m_pkthdr.rcvif->if_index);
        }
        /* sin6.sin6_scope_id = XXX: should be set if DST is a scoped addr */
        rt = rtalloc1_scoped((struct sockaddr *)&sin6, 0,
            RTF_CLONING | RTF_PRCLONING, m->m_pkthdr.rcvif->if_index);
        if (rt != NULL) {
                RT_LOCK(rt);
                if ((rt->rt_flags & RTF_HOST) &&
                    !(rt->rt_rmx.rmx_locks & RTV_MTU) &&
                    mtu < IN6_LINKMTU(rt->rt_ifp) &&
                    rt->rt_rmx.rmx_mtu > mtu) {
                        icmp6stat.icp6s_pmtuchg++;
                        rt->rt_rmx.rmx_mtu = mtu;
                }
                RT_UNLOCK(rt);
                rtfree(rt);
        }
}

/*
 * Process a Node Information Query packet, based on
 * draft-ietf-ipngwg-icmp-name-lookups-07.
 *
 * Spec incompatibilities:
 * - IPv6 Subject address handling
 * - IPv4 Subject address handling support missing
 * - Proxy reply (answer even if it's not for me)
 * - joins NI group address at in6_ifattach() time only, does not cope
 *   with hostname changes by sethostname(3)
 */
#define hostnamelen     strlen(hostname)
static struct mbuf *
ni6_input(m, off)
        struct mbuf *m;
        int off;
{
        struct icmp6_nodeinfo *ni6, *nni6;
        struct mbuf *n = NULL;
        u_int16_t qtype;
        int subjlen;
        int replylen = sizeof(struct ip6_hdr) + sizeof(struct icmp6_nodeinfo);
        struct ni_reply_fqdn *fqdn;
        int addrs;              /* for NI_QTYPE_NODEADDR */
        struct ifnet *ifp = NULL; /* for NI_QTYPE_NODEADDR */
        struct sockaddr_in6 sin6; /* double meaning; ip6_dst and subjectaddr */
        struct sockaddr_in6 sin6_d; /* XXX: we should retrieve this from m_aux */
        struct ip6_hdr *ip6;
        int oldfqdn = 0;        /* if 1, return pascal string (03 draft) */
        char *subj = NULL;

        ip6 = mtod(m, struct ip6_hdr *);
#ifndef PULLDOWN_TEST
        ni6 = (struct icmp6_nodeinfo *)(mtod(m, caddr_t) + off);
#else
        IP6_EXTHDR_GET(ni6, struct icmp6_nodeinfo *, m, off, sizeof(*ni6));
        if (ni6 == NULL) {
                /* m is already reclaimed */
                return (NULL);
        }
#endif

        /*
         * Validate IPv6 source address.
         * The default configuration MUST be to refuse answering queries from
         * global-scope addresses according to RFC4602.
         * Notes:
         *  - it's not very clear what "refuse" means; this implementation
         *    simply drops it.
         *  - it's not very easy to identify global-scope (unicast) addresses
         *    since there are many prefixes for them.  It should be safer
         *    and in practice sufficient to check "all" but loopback and
         *    link-local (note that site-local unicast was deprecated and
         *    ULA is defined as global scope-wise)
         */
        if ((icmp6_nodeinfo & ICMP6_NODEINFO_GLOBALOK) == 0 &&
            !IN6_IS_ADDR_LOOPBACK(&ip6->ip6_src) &&
            !IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src))
                goto bad;

        /*
         * Validate IPv6 destination address.
         *
         * The Responder must discard the Query without further processing
         * unless it is one of the Responder's unicast or anycast addresses, or
         * a link-local scope multicast address which the Responder has joined.
         * [RFC4602, Section 5.]
         */
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                if (!IN6_IS_ADDR_MC_LINKLOCAL(&ip6->ip6_dst))
                        goto bad;
                /* else it's a link-local multicast, fine */
        } else {                /* unicast or anycast */
                struct in6_ifaddr *ia6;

                if ((ia6 = ip6_getdstifaddr(m)) == NULL)
                        goto bad; /* XXX impossible */

                IFA_LOCK(&ia6->ia_ifa);
                if ((ia6->ia6_flags & IN6_IFF_TEMPORARY) &&
                    !(icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK)) {
                        nd6log((LOG_DEBUG, "ni6_input: ignore node info to "
                                "a temporary address in %s:%d",
                               __FILE__, __LINE__));
                        IFA_UNLOCK(&ia6->ia_ifa);
                        IFA_REMREF(&ia6->ia_ifa);
                        goto bad;
                }
                IFA_UNLOCK(&ia6->ia_ifa);
                IFA_REMREF(&ia6->ia_ifa);
        }

        /* validate query Subject field. */
        qtype = ntohs(ni6->ni_qtype);
        subjlen = m->m_pkthdr.len - off - sizeof(struct icmp6_nodeinfo);
        switch (qtype) {
        case NI_QTYPE_NOOP:
        case NI_QTYPE_SUPTYPES:
                /* 07 draft */
                if (ni6->ni_code == ICMP6_NI_SUBJ_FQDN && subjlen == 0)
                        break;
                /* FALLTHROUGH */
        case NI_QTYPE_FQDN:
        case NI_QTYPE_NODEADDR:
        case NI_QTYPE_IPV4ADDR:
                switch (ni6->ni_code) {
                case ICMP6_NI_SUBJ_IPV6:
#if ICMP6_NI_SUBJ_IPV6 != 0
                case 0:
#endif
                        /*
                         * backward compatibility - try to accept 03 draft
                         * format, where no Subject is present.
                         */
                        if (qtype == NI_QTYPE_FQDN && ni6->ni_code == 0 &&
                            subjlen == 0) {
                                oldfqdn++;
                                break;
                        }
#if ICMP6_NI_SUBJ_IPV6 != 0
                        if (ni6->ni_code != ICMP6_NI_SUBJ_IPV6)
                                goto bad;
#endif

                        if (subjlen != sizeof(struct in6_addr))
                                goto bad;

                        /*
                         * Validate Subject address.
                         *
                         * Not sure what exactly "address belongs to the node"
                         * means in the spec, is it just unicast, or what?
                         *
                         * At this moment we consider Subject address as
                         * "belong to the node" if the Subject address equals
                         * to the IPv6 destination address; validation for
                         * IPv6 destination address should have done enough
                         * check for us.
                         *
                         * We do not do proxy at this moment.
                         */
                        /* m_pulldown instead of copy? */
                        m_copydata(m, off + sizeof(struct icmp6_nodeinfo),
                            subjlen, (caddr_t)&sin6.sin6_addr);
                        sin6.sin6_scope_id = in6_addr2scopeid(m->m_pkthdr.rcvif,
                                                              &sin6.sin6_addr);
                        in6_embedscope(&sin6.sin6_addr, &sin6, NULL, NULL,
                            NULL);
                        bzero(&sin6_d, sizeof(sin6_d));
                        sin6_d.sin6_family = AF_INET6; /* not used, actually */
                        sin6_d.sin6_len = sizeof(sin6_d); /* ditto */
                        sin6_d.sin6_addr = ip6->ip6_dst;
                        sin6_d.sin6_scope_id = in6_addr2scopeid(m->m_pkthdr.rcvif,
                                                                &ip6->ip6_dst);
                        in6_embedscope(&sin6_d.sin6_addr, &sin6_d, NULL, NULL,
                            NULL);
                        subj = (char *)&sin6;
                        if (SA6_ARE_ADDR_EQUAL(&sin6, &sin6_d))
                                break;

                        /*
                         * XXX if we are to allow other cases, we should really
                         * be careful about scope here.
                         * basically, we should disallow queries toward IPv6
                         * destination X with subject Y,
                         * if scope(X) > scope(Y).
                         * if we allow scope(X) > scope(Y), it will result in
                         * information leakage across scope boundary.
                         */
                        goto bad;

                case ICMP6_NI_SUBJ_FQDN:
                        /*
                         * Validate Subject name with gethostname(3).
                         *
                         * The behavior may need some debate, since:
                         * - we are not sure if the node has FQDN as
                         *   hostname (returned by gethostname(3)).
                         * - the code does wildcard match for truncated names.
                         *   however, we are not sure if we want to perform
                         *   wildcard match, if gethostname(3) side has
                         *   truncated hostname.
                         */
                        n = ni6_nametodns(hostname, hostnamelen, 0);
                        if (!n || n->m_next || n->m_len == 0)
                                goto bad;
                        IP6_EXTHDR_GET(subj, char *, m,
                            off + sizeof(struct icmp6_nodeinfo), subjlen);
                        if (subj == NULL)
                                goto bad;
                        if (!ni6_dnsmatch(subj, subjlen, mtod(n, const char *),
                                        n->m_len)) {
                                goto bad;
                        }
                        m_freem(n);
                        n = NULL;
                        break;

                case ICMP6_NI_SUBJ_IPV4:        /* XXX: to be implemented? */
                default:
                        goto bad;
                }
                break;
        }

        /* refuse based on configuration.  XXX ICMP6_NI_REFUSED? */
        switch (qtype) {
        case NI_QTYPE_FQDN:
                if ((icmp6_nodeinfo & ICMP6_NODEINFO_FQDNOK) == 0)
                        goto bad;
                break;
        case NI_QTYPE_NODEADDR:
        case NI_QTYPE_IPV4ADDR:
                if ((icmp6_nodeinfo & ICMP6_NODEINFO_NODEADDROK) == 0)
                        goto bad;
                break;
        }

        /* guess reply length */
        switch (qtype) {
        case NI_QTYPE_NOOP:
                break;          /* no reply data */
        case NI_QTYPE_SUPTYPES:
                replylen += sizeof(u_int32_t);
                break;
        case NI_QTYPE_FQDN:
                /* XXX will append an mbuf */
                replylen += offsetof(struct ni_reply_fqdn, ni_fqdn_namelen);
                break;
        case NI_QTYPE_NODEADDR:
                addrs = ni6_addrs(ni6, &ifp, subj);
                if ((replylen += addrs * (sizeof(struct in6_addr) +
                    sizeof(u_int32_t))) > MCLBYTES)
                        replylen = MCLBYTES; /* XXX: will truncate pkt later */
                break;
        case NI_QTYPE_IPV4ADDR:
                /* unsupported - should respond with unknown Qtype? */
                break;
        default:
                /*
                 * XXX: We must return a reply with the ICMP6 code
                 * `unknown Qtype' in this case.  However we regard the case
                 * as an FQDN query for backward compatibility.
                 * Older versions set a random value to this field,
                 * so it rarely varies in the defined qtypes.
                 * But the mechanism is not reliable...
                 * maybe we should obsolete older versions.
                 */
                qtype = NI_QTYPE_FQDN;
                /* XXX will append an mbuf */
                replylen += offsetof(struct ni_reply_fqdn, ni_fqdn_namelen);
                oldfqdn++;
                break;
        }

        /* allocate an mbuf to reply. */
        MGETHDR(n, M_DONTWAIT, m->m_type);      /* MAC-OK */
        if (n == NULL) {
                m_freem(m);
                if (ifp != NULL)
                        ifnet_release(ifp);
                return (NULL);
        }
        M_COPY_PKTHDR(n, m); /* just for recvif */
        if (replylen > MHLEN) {
                if (replylen > MCLBYTES) {
                        /*
                         * XXX: should we try to allocate more? But MCLBYTES
                         * is probably much larger than IPV6_MMTU...
                         */
                        goto bad;
                }
                MCLGET(n, M_DONTWAIT);
                if ((n->m_flags & M_EXT) == 0) {
                        goto bad;
                }
        }
        n->m_pkthdr.len = n->m_len = replylen;

        /* copy mbuf header and IPv6 + Node Information base headers */
        bcopy(mtod(m, caddr_t), mtod(n, caddr_t), sizeof(struct ip6_hdr));
        nni6 = (struct icmp6_nodeinfo *)(mtod(n, struct ip6_hdr *) + 1);
        bcopy((caddr_t)ni6, (caddr_t)nni6, sizeof(struct icmp6_nodeinfo));

        /* qtype dependent procedure */
        switch (qtype) {
        case NI_QTYPE_NOOP:
                nni6->ni_code = ICMP6_NI_SUCCESS;
                nni6->ni_flags = 0;
                break;
        case NI_QTYPE_SUPTYPES:
        {
                u_int32_t v;
                nni6->ni_code = ICMP6_NI_SUCCESS;
                nni6->ni_flags = htons(0x0000); /* raw bitmap */
                /* supports NOOP, SUPTYPES, FQDN, and NODEADDR */
                v = (u_int32_t)htonl(0x0000000f);
                bcopy(&v, nni6 + 1, sizeof(u_int32_t));
                break;
        }
        case NI_QTYPE_FQDN:
                nni6->ni_code = ICMP6_NI_SUCCESS;
                fqdn = (struct ni_reply_fqdn *)(mtod(n, caddr_t) +
                                                sizeof(struct ip6_hdr) +
                                                sizeof(struct icmp6_nodeinfo));
                nni6->ni_flags = 0; /* XXX: meaningless TTL */
                fqdn->ni_fqdn_ttl = 0;  /* ditto. */
                /*
                 * XXX do we really have FQDN in variable "hostname"?
                 */
                n->m_next = ni6_nametodns(hostname, hostnamelen, oldfqdn);
                if (n->m_next == NULL)
                        goto bad;
                /* XXX we assume that n->m_next is not a chain */
                if (n->m_next->m_next != NULL)
                        goto bad;
                n->m_pkthdr.len += n->m_next->m_len;
                break;
        case NI_QTYPE_NODEADDR:
        {
                int lenlim, copied;

                nni6->ni_code = ICMP6_NI_SUCCESS;
                n->m_pkthdr.len = n->m_len =
                    sizeof(struct ip6_hdr) + sizeof(struct icmp6_nodeinfo);
                lenlim = M_TRAILINGSPACE(n);
                copied = ni6_store_addrs(ni6, nni6, ifp, lenlim);
                /* XXX: reset mbuf length */
                n->m_pkthdr.len = n->m_len = sizeof(struct ip6_hdr) +
                        sizeof(struct icmp6_nodeinfo) + copied;
                break;
        }
        default:
                break;          /* XXX impossible! */
        }

        nni6->ni_type = ICMP6_NI_REPLY;
        m_freem(m);
        if (ifp != NULL)
                ifnet_release(ifp);
        return (n);

bad:
        m_freem(m);
        if (n)
                m_freem(n);
        if (ifp != NULL)
                ifnet_release(ifp);
        return (NULL);
}
#undef hostnamelen

/*
 * make a mbuf with DNS-encoded string.  no compression support.
 *
 * XXX names with less than 2 dots (like "foo" or "foo.section") will be
 * treated as truncated name (two \0 at the end).  this is a wild guess.
 */
static struct mbuf *
ni6_nametodns(name, namelen, old)
        const char *name;
        int namelen;
        int old;        /* return pascal string if non-zero */
{
        struct mbuf *m;
        char *cp, *ep;
        const char *p, *q;
        int i, len, nterm;

        if (old)
                len = namelen + 1;
        else
                len = MCLBYTES;

        /* because MAXHOSTNAMELEN is usually 256, we use cluster mbuf */
        MGET(m, M_DONTWAIT, MT_DATA);
        if (m && len > MLEN) {
                MCLGET(m, M_DONTWAIT);
                if ((m->m_flags & M_EXT) == 0)
                        goto fail;
        }
        if (!m)
                goto fail;
        m->m_next = NULL;

        if (old) {
                m->m_len = len;
                *mtod(m, char *) = namelen;
                bcopy(name, mtod(m, char *) + 1, namelen);
                return m;
        } else {
                m->m_len = 0;
                cp = mtod(m, char *);
                ep = mtod(m, char *) + M_TRAILINGSPACE(m);

                /* if not certain about my name, return empty buffer */
                if (namelen == 0)
                        return m;

                /*
                 * guess if it looks like shortened hostname, or FQDN.
                 * shortened hostname needs two trailing "\0".
                 */
                i = 0;
                for (p = name; p < name + namelen; p++) {
                        if (*p && *p == '.')
                                i++;
                }
                if (i < 2)
                        nterm = 2;
                else
                        nterm = 1;

                p = name;
                while (cp < ep && p < name + namelen) {
                        i = 0;
                        for (q = p; q < name + namelen && *q && *q != '.'; q++)
                                i++;
                        /* result does not fit into mbuf */
                        if (cp + i + 1 >= ep)
                                goto fail;
                        /*
                         * DNS label length restriction, RFC1035 page 8.
                         * "i == 0" case is included here to avoid returning
                         * 0-length label on "foo..bar".
                         */
                        if (i <= 0 || i >= 64)
                                goto fail;
                        *cp++ = i;
                        bcopy(p, cp, i);
                        cp += i;
                        p = q;
                        if (p < name + namelen && *p == '.')
                                p++;
                }
                /* termination */
                if (cp + nterm >= ep)
                        goto fail;
                while (nterm-- > 0)
                        *cp++ = '\0';
                m->m_len = cp - mtod(m, char *);
                return m;
        }

        panic("should not reach here");
        /* NOTREACHED */

 fail:
        if (m)
                m_freem(m);
        return NULL;
}

/*
 * check if two DNS-encoded string matches.  takes care of truncated
 * form (with \0\0 at the end).  no compression support.
 * XXX upper/lowercase match (see RFC2065)
 */
static int
ni6_dnsmatch(a, alen, b, blen)
        const char *a;
        int alen;
        const char *b;
        int blen;
{
        const char *a0, *b0;
        int l;

        /* simplest case - need validation? */
        if (alen == blen && bcmp(a, b, alen) == 0)
                return 1;

        a0 = a;
        b0 = b;

        /* termination is mandatory */
        if (alen < 2 || blen < 2)
                return 0;
        if (a0[alen - 1] != '\0' || b0[blen - 1] != '\0')
                return 0;
        alen--;
        blen--;

        while (a - a0 < alen && b - b0 < blen) {
                if (a - a0 + 1 > alen || b - b0 + 1 > blen)
                        return 0;

                if ((signed char)a[0] < 0 || (signed char)b[0] < 0)
                        return 0;
                /* we don't support compression yet */
                if (a[0] >= 64 || b[0] >= 64)
                        return 0;

                /* truncated case */
                if (a[0] == 0 && a - a0 == alen - 1)
                        return 1;
                if (b[0] == 0 && b - b0 == blen - 1)
                        return 1;
                if (a[0] == 0 || b[0] == 0)
                        return 0;

                if (a[0] != b[0])
                        return 0;
                l = a[0];
                if (a - a0 + 1 + l > alen || b - b0 + 1 + l > blen)
                        return 0;
                if (bcmp(a + 1, b + 1, l) != 0)
                        return 0;

                a += 1 + l;
                b += 1 + l;
        }

        if (a - a0 == alen && b - b0 == blen)
                return 1;
        else
                return 0;
}

/*
 * calculate the number of addresses to be returned in the node info reply.
 */
static int
ni6_addrs(ni6, ifpp, subj)
        struct icmp6_nodeinfo *ni6;
        struct ifnet **ifpp;
        char *subj;
{
        struct ifnet *ifp;
        struct in6_ifaddr *ifa6;
        struct ifaddr *ifa;
        struct sockaddr_in6 *subj_ip6 = NULL; /* XXX pedant */
        int addrs = 0, addrsofif, iffound = 0;
        int niflags = ni6->ni_flags;

        if (ifpp != NULL)
                *ifpp = NULL;

        if ((niflags & NI_NODEADDR_FLAG_ALL) == 0) {
                switch (ni6->ni_code) {
                case ICMP6_NI_SUBJ_IPV6:
                        if (subj == NULL) /* must be impossible... */
                                return(0);
                        subj_ip6 = (struct sockaddr_in6 *)(void *)subj;
                        break;
                default:
                        /*
                         * XXX: we only support IPv6 subject address for
                         * this Qtype.
                         */
                        return (0);
                }
        }

        ifnet_head_lock_shared();
        TAILQ_FOREACH(ifp, &ifnet_head, if_list) {
                addrsofif = 0;
                ifnet_lock_shared(ifp);
                TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list)
                {
                        IFA_LOCK(ifa);
                        if (ifa->ifa_addr->sa_family != AF_INET6) {
                                IFA_UNLOCK(ifa);
                                continue;
                        }
                        ifa6 = (struct in6_ifaddr *)ifa;

                        if ((niflags & NI_NODEADDR_FLAG_ALL) == 0 &&
                            IN6_ARE_ADDR_EQUAL(&subj_ip6->sin6_addr,
                                               &ifa6->ia_addr.sin6_addr))
                                iffound = 1;

                        /*
                         * IPv4-mapped addresses can only be returned by a
                         * Node Information proxy, since they represent
                         * addresses of IPv4-only nodes, which perforce do
                         * not implement this protocol.
                         * [icmp-name-lookups-07, Section 5.4]
                         * So we don't support NI_NODEADDR_FLAG_COMPAT in
                         * this function at this moment.
                         */

                        /* What do we have to do about ::1? */
                        switch (in6_addrscope(&ifa6->ia_addr.sin6_addr)) {
                        case IPV6_ADDR_SCOPE_LINKLOCAL:
                                if ((niflags & NI_NODEADDR_FLAG_LINKLOCAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        case IPV6_ADDR_SCOPE_SITELOCAL:
                                if ((niflags & NI_NODEADDR_FLAG_SITELOCAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        case IPV6_ADDR_SCOPE_GLOBAL:
                                if ((niflags & NI_NODEADDR_FLAG_GLOBAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        default:
                                IFA_UNLOCK(ifa);
                                continue;
                        }

                        /*
                         * check if anycast is okay.
                         * XXX: just experimental.  not in the spec.
                         */
                        if ((ifa6->ia6_flags & IN6_IFF_ANYCAST) != 0 &&
                            (niflags & NI_NODEADDR_FLAG_ANYCAST) == 0) {
                                IFA_UNLOCK(ifa);
                                continue; /* we need only unicast addresses */
                        }
                        if ((ifa6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                            (icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK) == 0) {
                                IFA_UNLOCK(ifa);
                                continue;
                        }
                        addrsofif++; /* count the address */
                        IFA_UNLOCK(ifa);
                }
                ifnet_lock_done(ifp);
                if (iffound) {
                        if (ifpp != NULL) {
                                *ifpp = ifp;
                                ifnet_reference(ifp);
                        }
                        ifnet_head_done();
                        return(addrsofif);
                }

                addrs += addrsofif;
        }
        ifnet_head_done();

        return (addrs);
}

static int
ni6_store_addrs(ni6, nni6, ifp0, resid)
        struct icmp6_nodeinfo *ni6, *nni6;
        struct ifnet *ifp0;
        int resid;
{
        struct ifnet *ifp = ifp0;
        struct in6_ifaddr *ifa6;
        struct ifaddr *ifa;
        struct ifnet *ifp_dep = NULL;
        int copied = 0, allow_deprecated = 0;
        u_char *cp = (u_char *)(nni6 + 1);
        int niflags = ni6->ni_flags;
        u_int32_t ltime;
        struct timeval timenow;

        getmicrotime(&timenow);

        if (ifp0 == NULL && !(niflags & NI_NODEADDR_FLAG_ALL))
                return (0);     /* needless to copy */

  again:

        ifnet_head_lock_shared();
        if (ifp == NULL)
                ifp = TAILQ_FIRST(&ifnet_head);

        for (; ifp; ifp = TAILQ_NEXT(ifp, if_list)) {
                ifnet_lock_shared(ifp);
                for (ifa = ifp->if_addrlist.tqh_first; ifa;
                     ifa = ifa->ifa_list.tqe_next) {
                        IFA_LOCK(ifa);
                        if (ifa->ifa_addr->sa_family != AF_INET6) {
                                IFA_UNLOCK(ifa);
                                continue;
                        }
                        ifa6 = (struct in6_ifaddr *)ifa;

                        if ((ifa6->ia6_flags & IN6_IFF_DEPRECATED) != 0 &&
                            allow_deprecated == 0) {
                                /*
                                 * prefererred address should be put before
                                 * deprecated addresses.
                                 */

                                /* record the interface for later search */
                                if (ifp_dep == NULL)
                                        ifp_dep = ifp;

                                IFA_UNLOCK(ifa);
                                continue;
                        } else if ((ifa6->ia6_flags & IN6_IFF_DEPRECATED) == 0 &&
                            allow_deprecated != 0) {
                                IFA_UNLOCK(ifa);
                                continue; /* we now collect deprecated addrs */
                        }
                        /* What do we have to do about ::1? */
                        switch (in6_addrscope(&ifa6->ia_addr.sin6_addr)) {
                        case IPV6_ADDR_SCOPE_LINKLOCAL:
                                if ((niflags & NI_NODEADDR_FLAG_LINKLOCAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        case IPV6_ADDR_SCOPE_SITELOCAL:
                                if ((niflags & NI_NODEADDR_FLAG_SITELOCAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        case IPV6_ADDR_SCOPE_GLOBAL:
                                if ((niflags & NI_NODEADDR_FLAG_GLOBAL) == 0) {
                                        IFA_UNLOCK(ifa);
                                        continue;
                                }
                                break;
                        default:
                                IFA_UNLOCK(ifa);
                                continue;
                        }

                        /*
                         * check if anycast is okay.
                         * XXX: just experimental.  not in the spec.
                         */
                        if ((ifa6->ia6_flags & IN6_IFF_ANYCAST) != 0 &&
                            (niflags & NI_NODEADDR_FLAG_ANYCAST) == 0) {
                                IFA_UNLOCK(ifa);
                                continue;
                        }
                        if ((ifa6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                            (icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK) == 0) {
                                IFA_UNLOCK(ifa);
                                continue;
                        }

                        /* now we can copy the address */
                        if (resid < sizeof(struct in6_addr) +
                            sizeof(u_int32_t)) {
                                IFA_UNLOCK(ifa);
                                /*
                                 * We give up much more copy.
                                 * Set the truncate flag and return.
                                 */
                                nni6->ni_flags |=
                                        NI_NODEADDR_FLAG_TRUNCATE;
                                ifnet_lock_done(ifp);
                                ifnet_head_done();
                                return(copied);
                        }

                        /*
                         * Set the TTL of the address.
                         * The TTL value should be one of the following
                         * according to the specification:
                         *
                         * 1. The remaining lifetime of a DHCP lease on the
                         *    address, or
                         * 2. The remaining Valid Lifetime of a prefix from
                         *    which the address was derived through Stateless
                         *    Autoconfiguration.
                         *
                         * Note that we currently do not support stateful
                         * address configuration by DHCPv6, so the former
                         * case can't happen.
                         */
                        if (ifa6->ia6_lifetime.ia6t_expire == 0 &&
                            (ifa6->ia6_flags & IN6_IFF_TEMPORARY) == 0)
                                ltime = ND6_INFINITE_LIFETIME;
                        else {
                                if (ifa6->ia6_lifetime.ia6t_expire >
                                    timenow.tv_sec)
                                        ltime = htonl(ifa6->ia6_lifetime.ia6t_expire - timenow.tv_sec);
                                else
                                        ltime = 0;
                        }

                        bcopy(&ltime, cp, sizeof(u_int32_t));
                        cp += sizeof(u_int32_t);

                        /* copy the address itself */
                        bcopy(&ifa6->ia_addr.sin6_addr, cp,
                              sizeof(struct in6_addr));
                        /* XXX: KAME link-local hack; remove ifindex */
                        if (IN6_IS_ADDR_LINKLOCAL(&ifa6->ia_addr.sin6_addr))
                                ((struct in6_addr *)(void *)cp)->s6_addr16[1] = 0;
                        cp += sizeof(struct in6_addr);

                        resid -= (sizeof(struct in6_addr) + sizeof(u_int32_t));
                        copied += (sizeof(struct in6_addr) +
                                   sizeof(u_int32_t));
                        IFA_UNLOCK(ifa);
                }
                ifnet_lock_done(ifp);
                if (ifp0)       /* we need search only on the specified IF */
                        break;
        }
        ifnet_head_done();

        if (allow_deprecated == 0 && ifp_dep != NULL) {
                ifp = ifp_dep;
                allow_deprecated = 1;

                goto again;
        }

        return(copied);
}

/*
 * XXX almost dup'ed code with rip6_input.
 */
static int
icmp6_rip6_input(mp, off)
        struct  mbuf **mp;
        int     off;
{
        struct mbuf *m = *mp;
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
        struct in6pcb *in6p;
        struct in6pcb *last = NULL;
        struct sockaddr_in6 rip6src;
        struct icmp6_hdr *icmp6;
        struct mbuf *opts = NULL;
        int ret = 0;

#ifndef PULLDOWN_TEST
        /* this is assumed to be safe. */
        icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
#else
        IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off, sizeof(*icmp6));
        if (icmp6 == NULL) {
                /* m is already reclaimed */
                return IPPROTO_DONE;
        }
#endif

        /*
         * XXX: the address may have embedded scope zone ID, which should be
         * hidden from applications.
         */
        bzero(&rip6src, sizeof(rip6src));
        rip6src.sin6_family = AF_INET6;
        rip6src.sin6_len = sizeof(struct sockaddr_in6);
        rip6src.sin6_addr = ip6->ip6_src;
        if (sa6_recoverscope(&rip6src, TRUE)) 
                return (IPPROTO_DONE);

        lck_rw_lock_shared(ripcbinfo.mtx);
        LIST_FOREACH(in6p, &ripcb, inp_list)
        {
                if ((in6p->inp_vflag & INP_IPV6) == 0)
                        continue;
                if (in6p->in6p_ip6_nxt != IPPROTO_ICMPV6)
                        continue;
                if (!IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_laddr) &&
                   !IN6_ARE_ADDR_EQUAL(&in6p->in6p_laddr, &ip6->ip6_dst))
                        continue;
                if (!IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_faddr) &&
                   !IN6_ARE_ADDR_EQUAL(&in6p->in6p_faddr, &ip6->ip6_src))
                        continue;
                if (in6p->in6p_icmp6filt
                    && ICMP6_FILTER_WILLBLOCK(icmp6->icmp6_type,
                                 in6p->in6p_icmp6filt))
                        continue;
                if (last) {
                        struct  mbuf *n;
                        if ((n = m_copy(m, 0, (int)M_COPYALL)) != NULL) {
                                if ((last->in6p_flags & IN6P_CONTROLOPTS) != 0 ||
                                    (last->in6p_socket->so_options & SO_TIMESTAMP) != 0 ||
                                    (last->in6p_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0) {
                                        ret = ip6_savecontrol(last, n, &opts);
                                        if (ret != 0) {
                                                m_freem(n);
                                                m_freem(opts);
                                                last = in6p;
                                                continue;
                                        }
                                }
                                /* strip intermediate headers */
                                m_adj(n, off);
                                so_recv_data_stat(last->in6p_socket, m, 0);
                                if (sbappendaddr(&last->in6p_socket->so_rcv,
                                                 (struct sockaddr *)&rip6src,
                                                 n, opts, NULL) != 0) {
                                        sorwakeup(last->in6p_socket);
                                }
                                opts = NULL;
                        }
                }
                last = in6p;
        }
        if (last) {
                if ((last->in6p_flags & INP_CONTROLOPTS) != 0 ||
                    (last->in6p_socket->so_options & SO_TIMESTAMP) != 0 ||
                    (last->in6p_socket->so_options & SO_TIMESTAMP_MONOTONIC) != 0) {
                        ret = ip6_savecontrol(last, m, &opts);
                        if (ret != 0) {
                                goto error;
                        }
                }
                /* strip intermediate headers */
                m_adj(m, off);
                so_recv_data_stat(last->in6p_socket, m, 0);
                if (sbappendaddr(&last->in6p_socket->so_rcv,
                                 (struct sockaddr *)&rip6src, m, opts, NULL) != 0) {
                        sorwakeup(last->in6p_socket);
                }
        } else {
                goto error;
        }
        lck_rw_done(ripcbinfo.mtx);
        return IPPROTO_DONE;

error:
        lck_rw_done(ripcbinfo.mtx);
        m_freem(m);
        m_freem(opts);
        ip6stat.ip6s_delivered--;
        return IPPROTO_DONE;
}

/*
 * Reflect the ip6 packet back to the source.
 * OFF points to the icmp6 header, counted from the top of the mbuf.
 */
void
icmp6_reflect(m, off)
        struct  mbuf *m;
        size_t off;
{
        struct ip6_hdr *ip6;
        struct icmp6_hdr *icmp6;
        struct in6_ifaddr *ia;
        struct in6_addr t, src_storage, *src = 0;
        int plen;
        int type, code;
        struct ifnet *outif = NULL;
        struct sockaddr_in6 sa6_src, sa6_dst;
        struct nd_ifinfo *ndi;
        u_int32_t oflow;
        struct ip6_out_args ip6oa =
            { IFSCOPE_NONE, { 0 }, IP6OAF_SELECT_SRCIF | IP6OAF_BOUND_SRCADDR };

        if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.rcvif != NULL) {
                ip6oa.ip6oa_boundif = m->m_pkthdr.rcvif->if_index;
                ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
        }

        /* too short to reflect */
        if (off < sizeof(struct ip6_hdr)) {
                nd6log((LOG_DEBUG,
                    "sanity fail: off=%lx, sizeof(ip6)=%lx in %s:%d\n",
                    (u_int32_t)off, (u_int32_t)sizeof(struct ip6_hdr),
                    __FILE__, __LINE__));
                goto bad;
        }

        /*
         * If there are extra headers between IPv6 and ICMPv6, strip
         * off that header first.
         */
#if DIAGNOSTIC
        if (sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr) > MHLEN)
                panic("assumption failed in icmp6_reflect");
#endif
        if (off > sizeof(struct ip6_hdr)) {
                size_t l;
                struct ip6_hdr nip6;

                l = off - sizeof(struct ip6_hdr);
                m_copydata(m, 0, sizeof(nip6), (caddr_t)&nip6);
                m_adj(m, l);
                l = sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr);
                if (m->m_len < l) {
                        if ((m = m_pullup(m, l)) == NULL)
                                return;
                }
                bcopy((caddr_t)&nip6, mtod(m, caddr_t), sizeof(nip6));
        } else /* off == sizeof(struct ip6_hdr) */ {
                size_t l;
                l = sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr);
                if (m->m_len < l) {
                        if ((m = m_pullup(m, l)) == NULL)
                                return;
                }
        }
        plen = m->m_pkthdr.len - sizeof(struct ip6_hdr);
        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_nxt = IPPROTO_ICMPV6;
        icmp6 = (struct icmp6_hdr *)(ip6 + 1);
        type = icmp6->icmp6_type; /* keep type for statistics */
        code = icmp6->icmp6_code; /* ditto. */

        t = ip6->ip6_dst;
        /*
         * ip6_input() drops a packet if its src is multicast.
         * So, the src is never multicast.
         */
        ip6->ip6_dst = ip6->ip6_src;

        /*
         * XXX: make sure to embed scope zone information, using
         * already embedded IDs or the received interface (if any).
         * Note that rcvif may be NULL.
         */
        bzero(&sa6_src, sizeof(sa6_src));
        sa6_src.sin6_family = AF_INET6;
        sa6_src.sin6_len = sizeof(sa6_src);
        sa6_src.sin6_addr = ip6->ip6_dst;
        in6_recoverscope(&sa6_src, &ip6->ip6_dst, m->m_pkthdr.rcvif);
        in6_embedscope(&ip6->ip6_dst, &sa6_src, NULL, NULL, NULL);
        bzero(&sa6_dst, sizeof(sa6_dst));
        sa6_dst.sin6_family = AF_INET6;
        sa6_dst.sin6_len = sizeof(sa6_dst);
        sa6_dst.sin6_addr = t;
        in6_recoverscope(&sa6_dst, &t, m->m_pkthdr.rcvif);
        in6_embedscope(&t, &sa6_dst, NULL, NULL, NULL);

        /*
         * If the incoming packet was addressed directly to us(i.e. unicast),
         * use dst as the src for the reply.
         * The IN6_IFF_NOTREADY case should be VERY rare, but is possible
         * (for example) when we encounter an error while forwarding procedure
         * destined to a duplicated address of ours.
         * Note that ip6_getdstifaddr() may fail if we are in an error handling
         * procedure of an outgoing packet of our own, in which case we need
         * to search in the ifaddr list.
         */
        lck_rw_lock_shared(&in6_ifaddr_rwlock);
        for (ia = in6_ifaddrs; ia; ia = ia->ia_next) {
                IFA_LOCK(&ia->ia_ifa);
                if (IN6_ARE_ADDR_EQUAL(&t, &ia->ia_addr.sin6_addr) &&
                    (ia->ia6_flags & (IN6_IFF_ANYCAST|IN6_IFF_NOTREADY)) == 0) {
                        IFA_UNLOCK(&ia->ia_ifa);
                        src = &t;
                        break;
                }
                IFA_UNLOCK(&ia->ia_ifa);
        }
        lck_rw_done(&in6_ifaddr_rwlock);
        if (ia == NULL && IN6_IS_ADDR_LINKLOCAL(&t) && (m->m_flags & M_LOOP)) {
                /*
                 * This is the case if the dst is our link-local address
                 * and the sender is also ourselves.
                 */
                src = &t;
        }

        if (src == NULL) {
                int e;
                struct sockaddr_in6 sin6;
                struct route_in6 ro;

                /*
                 * This case matches to multicasts, our anycast, or unicasts
                 * that we do not own.  Select a source address based on the
                 * source address of the erroneous packet.
                 */
                bzero(&sin6, sizeof(sin6));
                sin6.sin6_family = AF_INET6;
                sin6.sin6_len = sizeof(sin6);
                sin6.sin6_addr = ip6->ip6_dst; /* zone ID should be embedded */

                bzero(&ro, sizeof(ro));
                /*
                 * in6_selectsrc() might return outif with its reference held
                 * even in the error case, so we always need to release it
                 * if non-NULL.
                 */
                src = in6_selectsrc(&sin6, NULL, NULL, &ro, &outif,
                    &src_storage, ip6oa.ip6oa_boundif, &e);
                if (ro.ro_rt)
                        rtfree(ro.ro_rt); /* XXX: we could use this */
                if (src == NULL) {
                        nd6log((LOG_DEBUG,
                            "icmp6_reflect: source can't be determined: "
                            "dst=%s, error=%d\n",
                            ip6_sprintf(&sa6_src.sin6_addr), e));
                        goto bad;
                }
        }
        oflow = ip6->ip6_flow; /* Save for later */
        ip6->ip6_src = *src;
        ip6->ip6_flow = 0;
        ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
        ip6->ip6_vfc |= IPV6_VERSION;
        if (icmp6->icmp6_type == ICMP6_ECHO_REPLY && icmp6->icmp6_code == 0) {
                ip6->ip6_flow |= (oflow & htonl(0x0ff00000));
        }
        ip6->ip6_nxt = IPPROTO_ICMPV6;
        lck_rw_lock_shared(nd_if_rwlock);
        if (outif != NULL && (ndi = ND_IFINFO(outif)) != NULL &&
            ndi->initialized) {
                lck_mtx_lock(&ndi->lock);
                ip6->ip6_hlim = ndi->chlim;
                lck_mtx_unlock(&ndi->lock);
        }
        if (m->m_pkthdr.rcvif != NULL &&
            (ndi = ND_IFINFO(m->m_pkthdr.rcvif)) != NULL &&
            ndi->initialized) {
                /* XXX: This may not be the outgoing interface */
                lck_mtx_lock(&ndi->lock);
                ip6->ip6_hlim = ndi->chlim;
                lck_mtx_unlock(&ndi->lock);
        } else {
                ip6->ip6_hlim = ip6_defhlim;
        }
        lck_rw_done(nd_if_rwlock);
        /* Use the same traffic class as in the request to match IPv4 */
        icmp6->icmp6_cksum = 0;
        icmp6->icmp6_cksum = in6_cksum(m, IPPROTO_ICMPV6,
                                        sizeof(struct ip6_hdr), plen);

        /*
         * XXX option handling
         */

        m->m_flags &= ~(M_BCAST|M_MCAST);
#if IPSEC
        /* Don't lookup socket */
        if (ipsec_bypass == 0)
                (void)ipsec_setsocket(m, NULL);
#endif /*IPSEC*/

        if (outif != NULL) {
                ifnet_release(outif);
                outif = NULL;
        }
        m->m_pkthdr.rcvif = NULL;
        m->m_pkthdr.csum_data = 0;
        m->m_pkthdr.csum_flags = 0;
        ip6_output(m, NULL, NULL, IPV6_OUTARGS, NULL, &outif, &ip6oa);
        if (outif != NULL) {
                icmp6_ifoutstat_inc(outif, type, code);
                ifnet_release(outif);
        }
        return;

bad:
        m_freem(m);
        if (outif != NULL)
                ifnet_release(outif);
        return;
}

static const char *
icmp6_redirect_diag(src6, dst6, tgt6)
        struct in6_addr *src6;
        struct in6_addr *dst6;
        struct in6_addr *tgt6;
{
        static char buf[1024];
        snprintf(buf, sizeof(buf), "(src=%s dst=%s tgt=%s)",
                ip6_sprintf(src6), ip6_sprintf(dst6), ip6_sprintf(tgt6));
        return buf;
}

void
icmp6_redirect_input(m, off)
        struct mbuf *m;
        int off;
{
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
        struct nd_redirect *nd_rd;
        int icmp6len = ntohs(ip6->ip6_plen);
        char *lladdr = NULL;
        int lladdrlen = 0;
        u_char *redirhdr = NULL;
        int redirhdrlen = 0;
        struct rtentry *rt = NULL;
        int is_router;
        int is_onlink;
        struct in6_addr src6 = ip6->ip6_src;
        struct in6_addr redtgt6;
        struct in6_addr reddst6;
        union nd_opts ndopts;

        if (!m || !ifp)
                return;

        /*
         * If we are an advertising router on this interface,
         * don't update route by icmp6 redirect.
         */
        if (ifp->if_eflags & IFEF_IPV6_ROUTER)
                goto freeit;
        if (!icmp6_rediraccept)
                goto freeit;

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, icmp6len, return);
        nd_rd = (struct nd_redirect *)((caddr_t)ip6 + off);
#else
        IP6_EXTHDR_GET(nd_rd, struct nd_redirect *, m, off, icmp6len);
        if (nd_rd == NULL) {
                icmp6stat.icp6s_tooshort++;
                return;
        }
#endif
        redtgt6 = nd_rd->nd_rd_target;
        reddst6 = nd_rd->nd_rd_dst;

        if (in6_setscope(&redtgt6, m->m_pkthdr.rcvif, NULL) ||
            in6_setscope(&reddst6, m->m_pkthdr.rcvif, NULL)) {
                goto freeit;
        }

        /* validation */
        if (!IN6_IS_ADDR_LINKLOCAL(&src6)) {
                nd6log((LOG_ERR,
                        "ICMP6 redirect sent from %s rejected; "
                        "must be from linklocal\n", ip6_sprintf(&src6)));
                goto bad;
        }
        if (ip6->ip6_hlim != 255) {
                nd6log((LOG_ERR,
                        "ICMP6 redirect sent from %s rejected; "
                        "hlim=%d (must be 255)\n",
                        ip6_sprintf(&src6), ip6->ip6_hlim));
                goto bad;
        }
    {
        /* ip6->ip6_src must be equal to gw for icmp6->icmp6_reddst */
        struct sockaddr_in6 sin6;
        struct in6_addr *gw6;

        bzero(&sin6, sizeof(sin6));
        sin6.sin6_family = AF_INET6;
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        bcopy(&reddst6, &sin6.sin6_addr, sizeof(reddst6));
        rt = rtalloc1_scoped((struct sockaddr *)&sin6, 0, 0, ifp->if_index);
        if (rt) {
                RT_LOCK(rt);
                if (rt->rt_gateway == NULL ||
                    rt->rt_gateway->sa_family != AF_INET6) {
                        nd6log((LOG_ERR,
                            "ICMP6 redirect rejected; no route "
                            "with inet6 gateway found for redirect dst: %s\n",
                            icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                        RT_UNLOCK(rt);
                        rtfree(rt);
                        goto bad;
                }

                gw6 = &(((struct sockaddr_in6 *)(void *)
                    rt->rt_gateway)->sin6_addr);
                if (bcmp(&src6, gw6, sizeof(struct in6_addr)) != 0) {
                        nd6log((LOG_ERR,
                                "ICMP6 redirect rejected; "
                                "not equal to gw-for-src=%s (must be same): "
                                "%s\n",
                                ip6_sprintf(gw6),
                                icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                        RT_UNLOCK(rt);
                        rtfree(rt);
                        goto bad;
                }
        } else {
                nd6log((LOG_ERR,
                        "ICMP6 redirect rejected; "
                        "no route found for redirect dst: %s\n",
                        icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                goto bad;
        }
        RT_UNLOCK(rt);
        rtfree(rt);
        rt = NULL;
    }
        if (IN6_IS_ADDR_MULTICAST(&reddst6)) {
                nd6log((LOG_ERR,
                        "ICMP6 redirect rejected; "
                        "redirect dst must be unicast: %s\n",
                        icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                goto bad;
        }

        is_router = is_onlink = 0;
        if (IN6_IS_ADDR_LINKLOCAL(&redtgt6))
                is_router = 1;  /* router case */
        if (bcmp(&redtgt6, &reddst6, sizeof(redtgt6)) == 0)
                is_onlink = 1;  /* on-link destination case */
        if (!is_router && !is_onlink) {
                nd6log((LOG_ERR,
                        "ICMP6 redirect rejected; "
                        "neither router case nor onlink case: %s\n",
                        icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                goto bad;
        }
        /* validation passed */

        icmp6len -= sizeof(*nd_rd);
        nd6_option_init(nd_rd + 1, icmp6len, &ndopts);
        if (nd6_options(&ndopts) < 0) {
                nd6log((LOG_INFO, "icmp6_redirect_input: "
                        "invalid ND option, rejected: %s\n",
                        icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                /* nd6_options have incremented stats */
                goto freeit;
        }

        if (ndopts.nd_opts_tgt_lladdr) {
                lladdr = (char *)(ndopts.nd_opts_tgt_lladdr + 1);
                lladdrlen = ndopts.nd_opts_tgt_lladdr->nd_opt_len << 3;
        }

        if (ndopts.nd_opts_rh) {
                redirhdrlen = ndopts.nd_opts_rh->nd_opt_rh_len;
                redirhdr = (u_char *)(ndopts.nd_opts_rh + 1); /* xxx */
        }

        if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
                nd6log((LOG_INFO,
                        "icmp6_redirect_input: lladdrlen mismatch for %s "
                        "(if %d, icmp6 packet %d): %s\n",
                        ip6_sprintf(&redtgt6), ifp->if_addrlen, lladdrlen - 2,
                        icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                goto bad;
        }

        /* RFC 2461 8.3 */
        nd6_cache_lladdr(ifp, &redtgt6, lladdr, lladdrlen, ND_REDIRECT,
                         is_onlink ? ND_REDIRECT_ONLINK : ND_REDIRECT_ROUTER);

        if (!is_onlink) {       /* better router case.  perform rtredirect. */
                /* perform rtredirect */
                struct sockaddr_in6 sdst;
                struct sockaddr_in6 sgw;
                struct sockaddr_in6 ssrc;

                bzero(&sdst, sizeof(sdst));
                bzero(&sgw, sizeof(sgw));
                bzero(&ssrc, sizeof(ssrc));
                sdst.sin6_family = sgw.sin6_family = ssrc.sin6_family = AF_INET6;
                sdst.sin6_len = sgw.sin6_len = ssrc.sin6_len =
                        sizeof(struct sockaddr_in6);
                bcopy(&redtgt6, &sgw.sin6_addr, sizeof(struct in6_addr));
                bcopy(&reddst6, &sdst.sin6_addr, sizeof(struct in6_addr));
                bcopy(&src6, &ssrc.sin6_addr, sizeof(struct in6_addr));
                rtredirect(ifp, (struct sockaddr *)&sdst,
                    (struct sockaddr *)&sgw, NULL, RTF_GATEWAY | RTF_HOST,
                    (struct sockaddr *)&ssrc, NULL);
        }
        /* finally update cached route in each socket via pfctlinput */
    {
        struct sockaddr_in6 sdst;

        bzero(&sdst, sizeof(sdst));
        sdst.sin6_family = AF_INET6;
        sdst.sin6_len = sizeof(struct sockaddr_in6);
        bcopy(&reddst6, &sdst.sin6_addr, sizeof(struct in6_addr));

        /*
         * Radar 6843900
         * Release the IPv6 domain lock because we are going to take domain_proto_mtx
         * and could otherwise cause a deadlock with other threads taking these locks 
         * in the reverse order -- e.g. frag6_slowtimo() from pfslowtimo()
         */
        lck_mtx_unlock(inet6_domain_mutex);
        pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&sdst);
        lck_mtx_lock(inet6_domain_mutex);
#if IPSEC
        key_sa_routechange((struct sockaddr *)&sdst);
#endif
    }

 freeit:
        m_freem(m);
        return;

 bad:
        icmp6stat.icp6s_badredirect++;
        m_freem(m);
}

void
icmp6_redirect_output(m0, rt)
        struct mbuf *m0;
        struct rtentry *rt;
{
        struct ifnet *ifp;      /* my outgoing interface */
        struct in6_addr ifp_ll6;
        struct in6_addr *router_ll6;
        struct ip6_hdr *sip6;   /* m0 as struct ip6_hdr */
        struct mbuf *m = NULL;  /* newly allocated one */
        struct ip6_hdr *ip6;    /* m as struct ip6_hdr */
        struct nd_redirect *nd_rd;
        size_t maxlen;
        u_char *p;
        struct ifnet *outif = NULL;
        struct sockaddr_in6 src_sa;
        struct ip6_out_args ip6oa =
            { IFSCOPE_NONE, { 0 }, IP6OAF_SELECT_SRCIF | IP6OAF_BOUND_SRCADDR };

        icmp6_errcount(&icmp6stat.icp6s_outerrhist, ND_REDIRECT, 0);

        if (rt != NULL)
                RT_LOCK(rt);

        /* sanity check */
        if (!m0 || !rt || !(rt->rt_flags & RTF_UP) || !(ifp = rt->rt_ifp))
                goto fail;

        /*
         * If we are not a router to begin with, or not an advertising
         * router on this interface, don't send icmp6 redirect.
         */
        if (!ip6_forwarding || !(ifp->if_eflags & IFEF_IPV6_ROUTER))
                goto fail;

        /*
         * Address check:
         *  the source address must identify a neighbor, and
         *  the destination address must not be a multicast address
         *  [RFC 2461, sec 8.2]
         */
        sip6 = mtod(m0, struct ip6_hdr *);
        bzero(&src_sa, sizeof(src_sa));
        src_sa.sin6_family = AF_INET6;
        src_sa.sin6_len = sizeof(src_sa);
        src_sa.sin6_addr = sip6->ip6_src;
        /* we don't currently use sin6_scope_id, but eventually use it */
        src_sa.sin6_scope_id = in6_addr2scopeid(ifp, &sip6->ip6_src);
        RT_UNLOCK(rt);
        if (nd6_is_addr_neighbor(&src_sa, ifp, 0) == 0) {
                /* already unlocked */
                rt = NULL;
                goto fail;
        }
        RT_LOCK(rt);
        if (IN6_IS_ADDR_MULTICAST(&sip6->ip6_dst))
                goto fail;      /* what should we do here? */

        /* rate limit */
        if (icmp6_ratelimit(&sip6->ip6_src, ND_REDIRECT, 0))
                goto fail;

        /*
         * Since we are going to append up to 1280 bytes (= IPV6_MMTU),
         * we almost always ask for an mbuf cluster for simplicity.
         * (MHLEN < IPV6_MMTU is almost always true)
         */
#if IPV6_MMTU >= MCLBYTES
# error assumption failed about IPV6_MMTU and MCLBYTES
#endif
        MGETHDR(m, M_DONTWAIT, MT_HEADER);      /* MAC-OK */
        if (m && IPV6_MMTU >= MHLEN)
                MCLGET(m, M_DONTWAIT);
        if (!m)
                goto fail;
        m->m_pkthdr.rcvif = NULL;
        m->m_len = 0;
        maxlen = M_TRAILINGSPACE(m);
        maxlen = min(IPV6_MMTU, maxlen);
        /* just for safety */
        if (maxlen < sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr) +
            ((sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7)) {
                goto fail;
        }

        {
                /* get ip6 linklocal address for ifp(my outgoing interface). */
                struct in6_ifaddr *ia;
                if ((ia = in6ifa_ifpforlinklocal(ifp,
                                                 IN6_IFF_NOTREADY|
                                                 IN6_IFF_ANYCAST)) == NULL)
                        goto fail;
                IFA_LOCK(&ia->ia_ifa);
                ifp_ll6 = ia->ia_addr.sin6_addr;
                IFA_UNLOCK(&ia->ia_ifa);
                IFA_REMREF(&ia->ia_ifa);
        }

        /* get ip6 linklocal address for the router. */
        if (rt->rt_gateway && (rt->rt_flags & RTF_GATEWAY)) {
                struct sockaddr_in6 *sin6;
                sin6 = (struct sockaddr_in6 *)(void *)rt->rt_gateway;
                router_ll6 = &sin6->sin6_addr;
                if (!IN6_IS_ADDR_LINKLOCAL(router_ll6))
                        router_ll6 = (struct in6_addr *)NULL;
        } else
                router_ll6 = (struct in6_addr *)NULL;

        /* ip6 */
        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_flow = 0;
        ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
        ip6->ip6_vfc |= IPV6_VERSION;
        /* ip6->ip6_plen will be set later */
        ip6->ip6_nxt = IPPROTO_ICMPV6;
        ip6->ip6_hlim = 255;
        /* ip6->ip6_src must be linklocal addr for my outgoing if. */
        bcopy(&ifp_ll6, &ip6->ip6_src, sizeof(struct in6_addr));
        bcopy(&sip6->ip6_src, &ip6->ip6_dst, sizeof(struct in6_addr));

        /* ND Redirect */
        nd_rd = (struct nd_redirect *)(ip6 + 1);
        nd_rd->nd_rd_type = ND_REDIRECT;
        nd_rd->nd_rd_code = 0;
        nd_rd->nd_rd_reserved = 0;
        if (rt->rt_flags & RTF_GATEWAY) {
                /*
                 * nd_rd->nd_rd_target must be a link-local address in
                 * better router cases.
                 */
                if (!router_ll6)
                        goto fail;
                bcopy(router_ll6, &nd_rd->nd_rd_target,
                      sizeof(nd_rd->nd_rd_target));
                bcopy(&sip6->ip6_dst, &nd_rd->nd_rd_dst,
                      sizeof(nd_rd->nd_rd_dst));
        } else {
                /* make sure redtgt == reddst */
                bcopy(&sip6->ip6_dst, &nd_rd->nd_rd_target,
                      sizeof(nd_rd->nd_rd_target));
                bcopy(&sip6->ip6_dst, &nd_rd->nd_rd_dst,
                      sizeof(nd_rd->nd_rd_dst));
        }
        RT_UNLOCK(rt);
        rt = NULL;

        p = (u_char *)(nd_rd + 1);

        if (!router_ll6)
                goto nolladdropt;

        {
                /* target lladdr option */
                struct rtentry *rt_router = NULL;
                int len;
                struct sockaddr_dl *sdl;
                struct nd_opt_hdr *nd_opt;
                char *lladdr;

                /* Callee returns a locked route upon success */
                rt_router = nd6_lookup(router_ll6, 0, ifp, 0);
                if (!rt_router)
                        goto nolladdropt;
                RT_LOCK_ASSERT_HELD(rt_router);
                len = sizeof(*nd_opt) + ifp->if_addrlen;
                len = (len + 7) & ~7;   /* round by 8 */
                /* safety check */
                if (len + (p - (u_char *)ip6) > maxlen) {
                        RT_REMREF_LOCKED(rt_router);
                        RT_UNLOCK(rt_router);
                        goto nolladdropt;
                }

                if (!(rt_router->rt_flags & RTF_GATEWAY) &&
                        (rt_router->rt_flags & RTF_LLINFO) &&
                        (rt_router->rt_gateway->sa_family == AF_LINK) &&
                        (sdl = (struct sockaddr_dl *)(void *)
                        rt_router->rt_gateway) && sdl->sdl_alen) {
                                nd_opt = (struct nd_opt_hdr *)p;
                                nd_opt->nd_opt_type = ND_OPT_TARGET_LINKADDR;
                                nd_opt->nd_opt_len = len >> 3;
                                lladdr = (char *)(nd_opt + 1);
                                bcopy(LLADDR(sdl), lladdr, ifp->if_addrlen);
                                p += len;
                }
                RT_REMREF_LOCKED(rt_router);
                RT_UNLOCK(rt_router);
        }

nolladdropt:;

        m->m_pkthdr.len = m->m_len = p - (u_char *)ip6;

        /* just to be safe */
#ifdef M_DECRYPTED      /*not openbsd*/
        if (m0->m_flags & M_DECRYPTED)
                goto noredhdropt;
#endif
        if (p - (u_char *)ip6 > maxlen)
                goto noredhdropt;

    {
        /* redirected header option */
        int len;
        struct nd_opt_rd_hdr *nd_opt_rh;

        /*
         * compute the maximum size for icmp6 redirect header option.
         * XXX room for auth header?
         */
        len = maxlen - (p - (u_char *)ip6);
        len &= ~7;

        /* This is just for simplicity. */
        if (m0->m_pkthdr.len != m0->m_len) {
                if (m0->m_next) {
                        m_freem(m0->m_next);
                        m0->m_next = NULL;
                }
                m0->m_pkthdr.len = m0->m_len;
        }

        /*
         * Redirected header option spec (RFC2461 4.6.3) talks nothing
         * about padding/truncate rule for the original IP packet.
         * From the discussion on IPv6imp in Feb 1999, the consensus was:
         * - "attach as much as possible" is the goal
         * - pad if not aligned (original size can be guessed by original
         *   ip6 header)
         * Following code adds the padding if it is simple enough,
         * and truncates if not.
         */
        if (m0->m_next || m0->m_pkthdr.len != m0->m_len)
                panic("assumption failed in %s:%d\n", __FILE__, __LINE__);

        if (len - sizeof(*nd_opt_rh) < m0->m_pkthdr.len) {
                /* not enough room, truncate */
                m0->m_pkthdr.len = m0->m_len = len - sizeof(*nd_opt_rh);
        } else {
                /* enough room, pad or truncate */
                size_t extra;

                extra = m0->m_pkthdr.len % 8;
                if (extra) {
                        /* pad if easy enough, truncate if not */
                        if (8 - extra <= M_TRAILINGSPACE(m0)) {
                                /* pad */
                                m0->m_len += (8 - extra);
                                m0->m_pkthdr.len += (8 - extra);
                        } else {
                                /* truncate */
                                m0->m_pkthdr.len -= extra;
                                m0->m_len -= extra;
                        }
                }
                len = m0->m_pkthdr.len + sizeof(*nd_opt_rh);
                m0->m_pkthdr.len = m0->m_len = len - sizeof(*nd_opt_rh);
        }

        nd_opt_rh = (struct nd_opt_rd_hdr *)p;
        bzero(nd_opt_rh, sizeof(*nd_opt_rh));
        nd_opt_rh->nd_opt_rh_type = ND_OPT_REDIRECTED_HEADER;
        nd_opt_rh->nd_opt_rh_len = len >> 3;
        p += sizeof(*nd_opt_rh);
        m->m_pkthdr.len = m->m_len = p - (u_char *)ip6;

        /* connect m0 to m */
        m->m_next = m0;
        m->m_pkthdr.len = m->m_len + m0->m_len;
    }
noredhdropt:;

        /* XXX: clear embedded link IDs in the inner header */
        in6_clearscope(&sip6->ip6_src);
        in6_clearscope(&sip6->ip6_dst);
        in6_clearscope(&nd_rd->nd_rd_target);
        in6_clearscope(&nd_rd->nd_rd_dst);

        ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));

        nd_rd->nd_rd_cksum = 0;
        nd_rd->nd_rd_cksum
                = in6_cksum(m, IPPROTO_ICMPV6, sizeof(*ip6), ntohs(ip6->ip6_plen));

        /* send the packet to outside... */
#if IPSEC
        /* Don't lookup socket */
        if (ipsec_bypass == 0)
                (void)ipsec_setsocket(m, NULL);
#endif /*IPSEC*/

        ip6oa.ip6oa_boundif = ifp->if_index;
        ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;

        ip6_output(m, NULL, NULL, IPV6_OUTARGS, NULL, &outif, &ip6oa);
        if (outif) {
                icmp6_ifstat_inc(outif, ifs6_out_msg);
                icmp6_ifstat_inc(outif, ifs6_out_redirect);
                ifnet_release(outif);
        }
        icmp6stat.icp6s_outhist[ND_REDIRECT]++;

        return;

fail:
        if (rt != NULL)
                RT_UNLOCK(rt);
        if (m)
                m_freem(m);
        if (m0)
                m_freem(m0);
}

/*
 * ICMPv6 socket option processing.
 */
int
icmp6_ctloutput(so, sopt)
        struct socket *so;
        struct sockopt *sopt;
{
        int error = 0;
        int optlen;
        struct inpcb *inp = sotoinpcb(so);
        int level, op, optname;

        if (sopt) {
                level = sopt->sopt_level;
                op = sopt->sopt_dir;
                optname = sopt->sopt_name;
                optlen = sopt->sopt_valsize;
        } else
                level = op = optname = optlen = 0;

        if (level != IPPROTO_ICMPV6) {
                return EINVAL;
        }

        switch (op) {
        case PRCO_SETOPT:
                switch (optname) {
                case ICMP6_FILTER:
                    {
                        struct icmp6_filter *p;

                        if (optlen != 0 && optlen != sizeof(*p)) {
                                error = EMSGSIZE;
                                break;
                        }
                        if (inp->in6p_icmp6filt == NULL) {
                                error = EINVAL;
                                break;
                        }

                        if (optlen == 0) {
                                /* According to RFC 3542, an installed filter can be 
                                 * cleared by issuing a setsockopt for ICMP6_FILTER
                                 * with a zero length.
                                 */
                                ICMP6_FILTER_SETPASSALL(inp->in6p_icmp6filt);
                        } else {
                                error = sooptcopyin(sopt, inp->in6p_icmp6filt, optlen,
                                        optlen);
                        }
                        break;
                    }

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;

        case PRCO_GETOPT:
                switch (optname) {
                case ICMP6_FILTER:
                    {
                        if (inp->in6p_icmp6filt == NULL) {
                                error = EINVAL;
                                break;
                        }
                        error = sooptcopyout(sopt, inp->in6p_icmp6filt,
                                        min(sizeof(struct icmp6_filter), optlen));
                        break;
                    }

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;
        }

        return(error);
}

/*
 * ICMPv6 socket datagram option processing.
 */
int
icmp6_dgram_ctloutput(struct socket *so, struct sockopt *sopt)
{
        if (kauth_cred_issuser(so->so_cred))
                return icmp6_ctloutput(so, sopt);

        if (sopt->sopt_level == IPPROTO_ICMPV6) {
                switch (sopt->sopt_name) {
                        case ICMP6_FILTER:
                                return icmp6_ctloutput(so, sopt);
                        default:
                                return EPERM;
                }
        }

        if (sopt->sopt_level != IPPROTO_IPV6)
                return EINVAL;

        switch (sopt->sopt_name) {
                case IPV6_UNICAST_HOPS:
                case IPV6_CHECKSUM:
                case IPV6_V6ONLY:
                case IPV6_USE_MIN_MTU:
                case IPV6_RECVRTHDR:
                case IPV6_RECVPKTINFO:
                case IPV6_RECVHOPLIMIT:
                case IPV6_PATHMTU:
                case IPV6_PKTINFO:
                case IPV6_HOPLIMIT:
                case IPV6_HOPOPTS:
                case IPV6_DSTOPTS:
                case IPV6_MULTICAST_IF:
                case IPV6_MULTICAST_HOPS:
                case IPV6_MULTICAST_LOOP:
                case IPV6_JOIN_GROUP:
                case IPV6_LEAVE_GROUP:
                case IPV6_PORTRANGE:
                case IPV6_IPSEC_POLICY:
                case IPV6_RECVTCLASS:
                case IPV6_TCLASS:
                case IPV6_2292PKTOPTIONS:
                case IPV6_2292PKTINFO:
                case IPV6_2292HOPLIMIT:
                case IPV6_2292HOPOPTS:
                case IPV6_2292DSTOPTS:
                case IPV6_2292RTHDR:
                case IPV6_BOUND_IF:
                case IPV6_NO_IFT_CELLULAR:

                        return ip6_ctloutput(so, sopt);

                default:
                        return EPERM;
        }
}

__private_extern__ int
icmp6_dgram_send(struct socket *so, int flags, struct mbuf *m,
    struct sockaddr *nam, struct mbuf *control, struct proc *p)
{
#pragma unused(flags, p)
        int error = 0;
        struct inpcb *inp = sotoinpcb(so);
        struct sockaddr_in6 tmp;
        struct sockaddr_in6 *dst = (struct sockaddr_in6 *)(void *)nam;
        struct icmp6_hdr *icmp6;

        if (kauth_cred_issuser(so->so_cred))
                return rip6_output(m, so, (struct sockaddr_in6 *)(void *)nam,
                    control, 0);

        /* always copy sockaddr to avoid overwrites */
        if (so->so_state & SS_ISCONNECTED) {
                if (nam) {
                        m_freem(m);
                        return EISCONN;
                }
                /* XXX */
                bzero(&tmp, sizeof(tmp));
                tmp.sin6_family = AF_INET6;
                tmp.sin6_len = sizeof(struct sockaddr_in6);
                bcopy(&inp->in6p_faddr, &tmp.sin6_addr,
                          sizeof(struct in6_addr));
                dst = &tmp;
        } else {
                if (nam == NULL) {
                        m_freem(m);
                        return ENOTCONN;
                }
                tmp = *(struct sockaddr_in6 *)(void *)nam;
                dst = &tmp;
        }

        /*
         * For an ICMPv6 packet, we should know its type and code
         */
        if (so->so_proto->pr_protocol == IPPROTO_ICMPV6) {
                if (m->m_len < sizeof(struct icmp6_hdr) &&
                        (m = m_pullup(m, sizeof(struct icmp6_hdr))) == NULL) {
                                error = ENOBUFS;
                                goto bad;
                }
                icmp6 = mtod(m, struct icmp6_hdr *);

                /*
                 * Allow only to send echo request and node information request
                 * See RFC 2463 for Echo Request Message format
                 */
                if ((icmp6->icmp6_type == ICMP6_ECHO_REQUEST && icmp6->icmp6_code == 0) ||
                        (icmp6->icmp6_type == ICMP6_NI_QUERY &&
                         (icmp6->icmp6_code == ICMP6_NI_SUBJ_IPV6 ||
                          icmp6->icmp6_code == ICMP6_NI_SUBJ_FQDN))) {
                        /* Good */
                        ;
                } else {
                        error = EPERM;
                        goto bad;
                }
        }

#if ENABLE_DEFAULT_SCOPE
        if (dst->sin6_scope_id == 0) {  /* not change if specified  */
                        dst->sin6_scope_id = scope6_addr2default(&dst->sin6_addr);
        }
#endif

        return rip6_output(m, so, (struct sockaddr_in6 *)(void *)nam,
           control, 0);
bad:
        m_freem(m);
        return error;
}

/* Like rip6_attach but without root privilege enforcement */
__private_extern__ int
icmp6_dgram_attach(struct socket *so, int proto, struct proc *p)
{
        struct inpcb *inp;
        int error;

        inp = sotoinpcb(so);
        if (inp)
                panic("icmp6_dgram_attach");

                if (proto != IPPROTO_ICMPV6)
                        return EINVAL;

        error = soreserve(so, rip_sendspace, rip_recvspace);
        if (error)
                return error;
        error = in_pcballoc(so, &ripcbinfo, p);
        if (error)
                return error;
        inp = (struct inpcb *)so->so_pcb;
        inp->inp_vflag |= INP_IPV6;
        inp->in6p_ip6_nxt = IPPROTO_ICMPV6;
        inp->in6p_hops = -1;    /* use kernel default */
        inp->in6p_cksum = -1;
        MALLOC(inp->in6p_icmp6filt, struct icmp6_filter *,
               sizeof(struct icmp6_filter), M_PCB, M_WAITOK);
        if (inp->in6p_icmp6filt == NULL)
                return (ENOMEM);
        ICMP6_FILTER_SETPASSALL(inp->in6p_icmp6filt);
        return 0;
}



#ifndef HAVE_PPSRATECHECK
#ifndef timersub
#define timersub(tvp, uvp, vvp)                                         \
        do {                                                            \
                (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;          \
                (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;       \
                if ((vvp)->tv_usec < 0) {                               \
                        (vvp)->tv_sec--;                                \
                        (vvp)->tv_usec += 1000000;                      \
                }                                                       \
        } while (0)
#endif

/*
 * ppsratecheck(): packets (or events) per second limitation.
 */
static int
ppsratecheck(lasttime, curpps, maxpps)
        struct timeval *lasttime;
        int *curpps;
        int maxpps;     /* maximum pps allowed */
{
        struct timeval tv, delta;
        int rv;

        microtime(&tv);

        timersub(&tv, lasttime, &delta);

        /*
         * Check for 0,0 so that the message will be seen at least once.
         * If more than one second has passed since the last update of
         * lasttime, reset the counter.
         *
         * we do increment *curpps even in *curpps < maxpps case, as some may
         * try to use *curpps for stat purposes as well.
         */
        if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
            delta.tv_sec >= 1) {
                *lasttime = tv;
                *curpps = 0;
                rv = 1;
        } else if (maxpps < 0)
                rv = 1;
        else if (*curpps < maxpps)
                rv = 1;
        else
                rv = 0;

#if 1 /* DIAGNOSTIC? */
        /* be careful about wrap-around */
        if (*curpps + 1 > 0)
                *curpps = *curpps + 1;
#else
        /*
         * assume that there's not too many calls to this function.
         * not sure if the assumption holds, as it depends on *caller's*
         * behavior, not the behavior of this function.
         * IMHO it is wrong to make assumption on the caller's behavior,
         * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
         */
        *curpps = *curpps + 1;
#endif

        return (rv);
}
#endif

/*
 * Perform rate limit check.
 * Returns 0 if it is okay to send the icmp6 packet.
 * Returns 1 if the router SHOULD NOT send this icmp6 packet due to rate
 * limitation.
 *
 * XXX per-destination/type check necessary?
 */
static int
icmp6_ratelimit(
        __unused const struct in6_addr *dst,    /* not used at this moment */
        __unused const int type,                        /* not used at this moment */
        __unused const int code)                        /* not used at this moment */
{
        int ret;

        ret = 0;        /* okay to send */

        /* PPS limit */
        if (!ppsratecheck(&icmp6errppslim_last, &icmp6errpps_count,
            icmp6errppslim)) {
                /* The packet is subject to rate limit */
                ret++;
        }

        return ret;
}