path: root/sys/netinet6/icmp6.c

/*	$OpenBSD: icmp6.c,v 1.17 2000/06/13 16:36:11 itojun Exp $	*/
/*	$KAME: icmp6.c,v 1.113 2000/06/12 09:24:41 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/malloc.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 <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/in_systm.h>
#include <netinet/ip.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/nd6.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/ip6protosw.h>

#undef IPSEC

#include "faith.h"

#include <net/net_osdep.h>

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

struct icmp6stat icmp6stat;

extern struct in6pcb rawin6pcb;
extern struct timeval icmp6errratelim;
extern int icmp6_nodeinfo;
static struct rttimer_queue *icmp6_mtudisc_timeout_q = NULL;
extern int pmtu_expire;

static void icmp6_mtudisc_update __P((struct in6_addr *, struct icmp6_hdr *,
				      struct mbuf *));
static int icmp6_ratelimit __P((const struct in6_addr *, const int, const int));
static const char *icmp6_redirect_diag __P((struct in6_addr *,
	struct in6_addr *, struct in6_addr *));
static struct mbuf *ni6_input __P((struct mbuf *, int));
static struct mbuf *ni6_nametodns __P((const char *, int, int));
static int ni6_dnsmatch __P((const char *, int, const char *, int));
static int ni6_addrs __P((struct icmp6_nodeinfo *, struct mbuf *,
			  struct ifnet **));
static int ni6_store_addrs __P((struct icmp6_nodeinfo *, struct icmp6_nodeinfo *,
				struct ifnet *, int));
static struct rtentry *icmp6_mtudisc_clone __P((struct sockaddr *));
static void icmp6_mtudisc_timeout __P((struct rtentry *, struct rttimer *));

#ifdef COMPAT_RFC1885
static struct route_in6 icmp6_reflect_rt;
#endif

void
icmp6_init()
{
	mld6_init();
	icmp6_mtudisc_timeout_q = rt_timer_queue_create(pmtu_expire);
}

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

	icmp6stat.icp6s_error++;

#ifndef PULLDOWN_TEST
	IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), );
#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 *);

	/*
	 * Multicast destination check. For unrecognized option errors,
	 * this check has already done in ip6_unknown_opt(), so we can
	 * check only for other errors.
	 */
	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;

	/* 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), );
		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) {
		printf("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;

	if (IN6_IS_SCOPE_LINKLOCAL(&oip6->ip6_src))
		oip6->ip6_src.s6_addr16[1] = 0;
	if (IN6_IS_SCOPE_LINKLOCAL(&oip6->ip6_dst))
		oip6->ip6_dst.s6_addr16[1] = 0;

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

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

	return;

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

/*
 * Process a received ICMP6 message.
 */
int
icmp6_input(mp, offp, proto)
	struct mbuf **mp;
	int *offp, proto;
{
	struct mbuf *m = *mp, *n;
	struct ip6_hdr *ip6, *nip6;
	struct icmp6_hdr *icmp6, *nicmp6;
	int off = *offp;
	int icmp6len = m->m_pkthdr.len - *offp;
	int code, sum, noff;
	struct sockaddr_in6 icmp6src;

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

	/*
	 * 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;
	}

	/*
	 * 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) {
		log(LOG_ERR,
		    "ICMP6 checksum error(%d|%x) %s\n",
		    icmp6->icmp6_type,
		    sum,
		    ip6_sprintf(&ip6->ip6_src));
		icmp6stat.icp6s_checksum++;
		goto freeit;
	}

#if defined(NFAITH) && 0 < NFAITH
	if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
		/*
		 * Deliver very specific ICMP6 type only.
		 * This is important to deilver TOOBIG.  Otherwise PMTUD
		 * will not work.
		 */
		switch (icmp6->icmp6_type) {
		case ICMP6_DST_UNREACH:
		case ICMP6_PACKET_TOO_BIG:
		case ICMP6_TIME_EXCEEDED:
			break;
		default:
			goto freeit;
		}
	}
#endif

#ifdef IPSEC
	/* drop it if it does not match the default policy */
	if (ipsec6_in_reject(m, NULL)) {
		ipsecstat.in_polvio++;
		goto freeit;
	}
#endif

	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;
#ifdef COMPAT_RFC1885
		case ICMP6_DST_UNREACH_NOTNEIGHBOR:
			code = PRC_UNREACH_SRCFAIL;
			break;
#else
		case ICMP6_DST_UNREACH_BEYONDSCOPE:
			/* I mean "source address was incorrect." */
			code = PRC_PARAMPROB;
			break;
#endif
		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);
		if (code != 0)
			goto badcode;

		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:
		case ICMP6_TIME_EXCEED_REASSEMBLY:
			code += PRC_TIMXCEED_INTRANS;
			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 ((n = m_copy(m, 0, M_COPYALL)) == NULL) {
			/* Give up remote */
			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) {
#ifdef DIAGNOSTIC
				printf("MCLBYTES too small\n");
#endif
				/* Give up remote */
				m_freem(n0);
				break;
			}
			MGETHDR(n, M_DONTWAIT, n0->m_type);
			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);
				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 *);
			nicmp6 = (struct icmp6_hdr *)((caddr_t)nip6 + off);
			noff = off;
		}
		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);
		}
		break;

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

	case MLD6_LISTENER_QUERY:
	case MLD6_LISTENER_REPORT:
		if (icmp6len < sizeof(struct mld6_hdr))
			goto badlen;
		if (icmp6->icmp6_type == MLD6_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 ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
			/* give up local */
			mld6_input(m, off);
			m = NULL;
			goto freeit;
		}
		mld6_input(n, off);
		/* m stays. */
		break;

	case MLD6_LISTENER_DONE:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mlddone);
		if (icmp6len < sizeof(struct mld6_hdr))	/* necessary? */
			goto badlen;
		break;		/* nothing to be done in kernel */

	case MLD6_MTRACE_RESP:
	case MLD6_MTRACE:
		/* XXX: these two are experimental. not officially defind. */
		/* XXX: per-interface statistics? */
		break;		/* just pass it to applications */

	case ICMP6_WRUREQUEST:	/* ICMP6_FQDN_QUERY */
	    {
		enum { WRU, FQDN } mode;

		if (!icmp6_nodeinfo)
			break;

		if (icmp6len == sizeof(struct icmp6_hdr) + 4)
			mode = WRU;
		else if (icmp6len >= sizeof(struct icmp6_nodeinfo))
			mode = FQDN;
		else
			goto badlen;

		if (mode == FQDN) {
#ifndef PULLDOWN_TEST
			IP6_EXTHDR_CHECK(m, off, sizeof(struct icmp6_nodeinfo),
					 IPPROTO_DONE);
#endif
			n = m_copy(m, 0, M_COPYALL);
			if (n)
				n = ni6_input(n, off);
			/* XXX meaningless if n == NULL */
			noff = sizeof(struct ip6_hdr);
		} else {
			u_char *p;
			int maxlen, maxhlen;

			if (code != 0)
				goto badcode;
			maxlen = sizeof(*nip6) + sizeof(*nicmp6) + 4;
			if (maxlen >= MCLBYTES) {
#ifdef DIAGNOSTIC
				printf("MCLBYTES too small\n");
#endif
				/* Give up remote */
				break;
			}
			MGETHDR(n, M_DONTWAIT, m->m_type);
			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 */
				break;
			}
			n->m_len = 0;
			maxhlen = M_TRAILINGSPACE(n) - maxlen;
			if (maxhlen > hostnamelen)
				maxhlen = hostnamelen;
			/*
			 * 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));
			p = (u_char *)(nicmp6 + 1);
			bzero(p, 4);
			bcopy(hostname, p + 4, maxhlen); /*meaningless TTL*/
			noff = sizeof(struct ip6_hdr);
			M_COPY_PKTHDR(n, m); /* just for recvif */
			n->m_pkthdr.len = n->m_len = sizeof(struct ip6_hdr) +
				sizeof(struct icmp6_hdr) + 4 + maxhlen;
			nicmp6->icmp6_type = ICMP6_WRUREPLY;
			nicmp6->icmp6_code = 0;
		}
#undef hostnamelen
		if (n) {
			icmp6stat.icp6s_reflect++;
			icmp6stat.icp6s_outhist[ICMP6_WRUREPLY]++;
			icmp6_reflect(n, noff);
		}
		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 ((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. */
		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 ((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. */
		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 ((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. */
		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 ((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. */
		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 ((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. */
		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:
		printf("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 */
			break;
		}
	deliver:
		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),
			IPPROTO_DONE);
		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 IPPROTO_DONE;
		}
#endif
		bzero(&icmp6src, sizeof(icmp6src));
		icmp6src.sin6_len = sizeof(struct sockaddr_in6);
		icmp6src.sin6_family = AF_INET6;
		icmp6src.sin6_addr = ((struct ip6_hdr *)(icmp6 + 1))->ip6_dst;

		/* Detect the upper level protocol */
	    {
		void (*ctlfunc) __P((int, struct sockaddr *, void *));
		struct ip6_hdr *eip6 = (struct ip6_hdr *)(icmp6 + 1);
		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 inf. 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),
						 IPPROTO_DONE);
				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 IPPROTO_DONE;
				}
#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),
						 IPPROTO_DONE);
				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 IPPROTO_DONE;
				}
#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,
							 IPPROTO_DONE);
					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 IPPROTO_DONE;
					}
#endif
					/* just ignore a bogus header */
					if ((rth0->ip6r0_len % 2) == 0 &&
					    (hops = rth0->ip6r0_len/2))
						finaldst = (struct in6_addr *)(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),
						 IPPROTO_DONE);
				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 IPPROTO_DONE;
				}
#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 IPPROTO_DONE;
		}
#endif
		if (icmp6type == ICMP6_PACKET_TOO_BIG) {
			if (finaldst == NULL)
				finaldst = &((struct ip6_hdr *)(icmp6 + 1))->ip6_dst;
			icmp6_mtudisc_update(finaldst, icmp6, m);
		}

		ctlfunc = (void (*) __P((int, struct sockaddr *, void *)))
			(inet6sw[ip6_protox[nxt]].pr_ctlinput);
		if (ctlfunc) {
			ip6cp.ip6c_m = m;
			ip6cp.ip6c_ip6 = (struct ip6_hdr *)(icmp6 + 1);
			ip6cp.ip6c_off = eoff;
			(*ctlfunc)(code, (struct sockaddr *)&icmp6src, &ip6cp);
		}
	    }
		break;

	badcode:
		icmp6stat.icp6s_badcode++;
		break;

	badlen:
		icmp6stat.icp6s_badlen++;
		break;
	}

	rip6_input(&m, offp, IPPROTO_ICMPV6);
	return IPPROTO_DONE;

 freeit:
	m_freem(m);
	return IPPROTO_DONE;
}

static void
icmp6_mtudisc_update(dst, icmp6, m)
	struct in6_addr *dst;
	struct icmp6_hdr *icmp6;/* we can assume the validity of the pointer */
	struct mbuf *m;	/* currently unused but added for scoped addrs */
{
	u_int mtu = ntohl(icmp6->icmp6_mtu);
	struct rtentry *rt = NULL;
	struct sockaddr_in6 sin6;

	bzero(&sin6, sizeof(sin6));
	sin6.sin6_family = PF_INET6;
	sin6.sin6_len = sizeof(struct sockaddr_in6);
	sin6.sin6_addr = *dst;
	/* sin6.sin6_scope_id = XXX: should be set if DST is a scoped addr */
	rt = rtalloc1((struct sockaddr *)&sin6, 1);	/*clone*/
	if (!rt || (rt->rt_flags & RTF_HOST) == 0) {
		if (rt)
			RTFREE(rt);
		rt = icmp6_mtudisc_clone((struct sockaddr *)&sin6);
	}

	if (rt && (rt->rt_flags & RTF_HOST)
	    && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
		if (mtu < IPV6_MMTU) {
				/* xxx */
			rt->rt_rmx.rmx_locks |= RTV_MTU;
		} else if (mtu < rt->rt_ifp->if_mtu &&
			   rt->rt_rmx.rmx_mtu > mtu) {
			rt->rt_rmx.rmx_mtu = mtu;
		}
	}
	if (rt)
		RTFREE(rt);
}

/*
 * Process a Node Information Query packet, (roughly) based on
 * draft-ietf-ipngwg-icmp-name-lookups-05.
 * 
 * Spec incompatibilities:
 * - IPv6 Subject address handling
 * - IPv4 Subject address handling support missing
 * - Proxy reply (answer even if it's not for me)
 * - "Supported Qtypes" support missing
 * - joins NI group address at in6_ifattach() time only, does not cope
 *   with hostname changes by sethostname(3)
 */
#ifndef offsetof		/* XXX */
#define	offsetof(type, member)	((size_t)(&((type *)0)->member))
#endif
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;
	struct ip6_hdr *ip6;
	int oldfqdn = 0;	/* if 1, return pascal string (03 draft) */
	char *subj;

	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 destination address.
	 *
	 * We accept packets with the following IPv6 destination address:
	 * - Responder's unicast/anycast address,
	 * - link-local multicast address
	 * This is a violation to last paragraph in icmp-name-lookups-05
	 * page 4, which restricts IPv6 destination address of a query to:
	 * - Responder's unicast/anycast address,
	 * - NI group address for a name belongs to the Responder, or
	 * - NI group address for a name for which the Responder is providing
	 *   proxy service.
	 * (note: NI group address is a link-local multicast address)
	 *
	 * We allow any link-local multicast address, since "ping6 -w ff02::1"
	 * has been really useful for us debugging our network.  Also this is
	 * still questionable if the restriction in spec buy us security at all,
	 * since RFC2463 permits echo packet to multicast destination.
	 * Even if we forbid NI query to ff02::1, we can effectively get the
	 * same result as "ping6 -w ff02::1" by the following steps:
	 * - run "ping6 ff02::1", then
	 * - run "ping6 -w" for all addresses replied.
	 */
	bzero(&sin6, sizeof(sin6));
	sin6.sin6_family = AF_INET6;
	sin6.sin6_len = sizeof(struct sockaddr_in6);
	bcopy(&ip6->ip6_dst, &sin6.sin6_addr, sizeof(sin6.sin6_addr));
	/* XXX scopeid */
	if (ifa_ifwithaddr((struct sockaddr *)&sin6))
		; /*unicast/anycast, fine*/
	else if (IN6_IS_ADDR_MC_LINKLOCAL(&sin6.sin6_addr))
		; /*violates spec slightly, see above*/
	else
		goto bad;

	/* guess reply length */
	qtype = ntohs(ni6->ni_qtype);
	switch (qtype) {
	case NI_QTYPE_NOOP:
		break;		/* no reply data */
	case NI_QTYPE_SUPTYPES:
		goto bad;	/* xxx: to be implemented */
		break;
	case NI_QTYPE_FQDN:
		/* XXX will append a mbuf */
		replylen += offsetof(struct ni_reply_fqdn, ni_fqdn_namelen);
		break;
	case NI_QTYPE_NODEADDR:
		addrs = ni6_addrs(ni6, m, &ifp);
		if ((replylen += addrs * sizeof(struct in6_addr)) > MCLBYTES)
			replylen = MCLBYTES; /* XXX: we'll truncate later */
		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 a mbuf */
		replylen += offsetof(struct ni_reply_fqdn, ni_fqdn_namelen);
		oldfqdn++;
		break;
	}

	/* validate query Subject field. */
	subjlen = m->m_pkthdr.len - off - sizeof(struct icmp6_nodeinfo);
	switch (qtype) {
	case NI_QTYPE_NOOP:
	case NI_QTYPE_SUPTYPES:
		if (subjlen != 0)
			goto bad;
		break;

	case NI_QTYPE_FQDN:
	case NI_QTYPE_NODEADDR:
		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 (subjlen == 0) {
				oldfqdn++;
				break;
			}

			if (subjlen != sizeof(sin6.sin6_addr))
				goto bad;

			/*
			 * Validate Subject address.
			 *
			 * Not sure what exactly does "address belongs to the
			 * node" mean 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);
			/* XXX kame scope hack */
			if (IN6_IS_SCOPE_LINKLOCAL(&sin6.sin6_addr)) {
#ifdef FAKE_LOOPBACK_IF
				if ((m->m_flags & M_PKTHDR) != 0 &&
				    m->m_pkthdr.rcvif) {
					sin6.sin6_addr.s6_addr16[1] =
					    htons(m->m_pkthdr.rcvif->if_index);
				}
#else
				if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
					sin6.sin6_addr.s6_addr16[1] =
					    ip6->ip6_dst.s6_addr16[1];
				}
#endif
			}
			if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &sin6.sin6_addr))
				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;

	default:
		/* should never be here due to "switch (qtype)" above */
		goto bad;
	}

	/* allocate a mbuf to reply. */
	MGETHDR(n, M_DONTWAIT, m->m_type);
	if (n == NULL) {
		m_freem(m);
		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_flags = 0;
		break;
	case NI_QTYPE_SUPTYPES:
		goto bad;	/* xxx: to be implemented */
		break;
	case NI_QTYPE_FQDN:
		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;

		if (n->m_flags & M_EXT)
			lenlim = MCLBYTES - sizeof(struct ip6_hdr) -
				sizeof(struct icmp6_nodeinfo);
		else
			lenlim = MHLEN - sizeof(struct ip6_hdr) -
				sizeof(struct icmp6_nodeinfo);
		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;
	nni6->ni_code = ICMP6_NI_SUCESS;
	m_freem(m);
	return(n);

  bad:
	m_freem(m);
	if (n)
		m_freem(n);
	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 */
			if (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.
 */
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 ((int)a[0] < 0 || (int)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, m, ifpp)
	struct icmp6_nodeinfo *ni6;
	struct mbuf *m;
	struct ifnet **ifpp;
{
	register struct ifnet *ifp;
	register struct in6_ifaddr *ifa6;
	register struct ifaddr *ifa;
	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
	int addrs = 0, addrsofif, iffound = 0;

	for (ifp = TAILQ_FIRST(&ifnet); ifp; ifp = TAILQ_NEXT(ifp, if_list))
	{
		addrsofif = 0;
		for (ifa = ifp->if_addrlist.tqh_first; ifa;
		     ifa = ifa->ifa_list.tqe_next)
		{
			if (ifa->ifa_addr->sa_family != AF_INET6)
				continue;
			ifa6 = (struct in6_ifaddr *)ifa;

			if (!(ni6->ni_flags & NI_NODEADDR_FLAG_ALL) &&
			    IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
					       &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-05]
			 * So we don't support NI_NODEADDR_FLAG_COMPAT in
			 * this function at this moment.
			 */

			if (ifa6->ia6_flags & IN6_IFF_ANYCAST)
				continue; /* we need only unicast addresses */

			if ((ni6->ni_flags & (NI_NODEADDR_FLAG_LINKLOCAL |
					      NI_NODEADDR_FLAG_SITELOCAL |
					      NI_NODEADDR_FLAG_GLOBAL)) == 0)
				continue;

			/* What do we have to do about ::1? */
			switch(in6_addrscope(&ifa6->ia_addr.sin6_addr)) {
			 case IPV6_ADDR_SCOPE_LINKLOCAL:
				if (ni6->ni_flags & NI_NODEADDR_FLAG_LINKLOCAL)
					addrsofif++;
				break;
			 case IPV6_ADDR_SCOPE_SITELOCAL:
				if (ni6->ni_flags & NI_NODEADDR_FLAG_SITELOCAL)
					addrsofif++;
				break;
			 case IPV6_ADDR_SCOPE_GLOBAL:
				 if (ni6->ni_flags & NI_NODEADDR_FLAG_GLOBAL)
					 addrsofif++;
				 break;
			 default:
				 continue;
			}
		}
		if (iffound) {
			*ifpp = ifp;
			return(addrsofif);
		}

		addrs += addrsofif;
	}

	return(addrs);
}

static int
ni6_store_addrs(ni6, nni6, ifp0, resid)
	struct icmp6_nodeinfo *ni6, *nni6;
	struct ifnet *ifp0;
	int resid;
{
	register struct ifnet *ifp = ifp0 ? ifp0 : TAILQ_FIRST(&ifnet);
	register struct in6_ifaddr *ifa6;
	register struct ifaddr *ifa;
	int docopy, copied = 0;
	u_char *cp = (u_char *)(nni6 + 1);

	if (ifp0 == NULL && !(ni6->ni_flags & NI_NODEADDR_FLAG_ALL))
		return(0);	/* needless to copy */

	for (; ifp; ifp = TAILQ_NEXT(ifp, if_list))
	{
		for (ifa = ifp->if_addrlist.tqh_first; ifa;
		     ifa = ifa->ifa_list.tqe_next)
		{
			docopy = 0;

			if (ifa->ifa_addr->sa_family != AF_INET6)
				continue;
			ifa6 = (struct in6_ifaddr *)ifa;

			if (ifa6->ia6_flags & IN6_IFF_ANYCAST) {
				/* just experimental. not in the spec. */
				if (ni6->ni_flags & NI_NODEADDR_FLAG_ANYCAST)
					docopy = 1;
				else
					continue;
			}
			else {	/* unicast address */
				if (ni6->ni_flags & NI_NODEADDR_FLAG_ANYCAST)
					continue;
				else
					docopy = 1;
			}

			/* What do we have to do about ::1? */
			switch(in6_addrscope(&ifa6->ia_addr.sin6_addr)) {
			 case IPV6_ADDR_SCOPE_LINKLOCAL:
				if (ni6->ni_flags & NI_NODEADDR_FLAG_LINKLOCAL)
					docopy = 1;
				break;
			 case IPV6_ADDR_SCOPE_SITELOCAL:
				if (ni6->ni_flags & NI_NODEADDR_FLAG_SITELOCAL)
					docopy = 1;
				break;
			 case IPV6_ADDR_SCOPE_GLOBAL:
				 if (ni6->ni_flags & NI_NODEADDR_FLAG_GLOBAL)
					 docopy = 1;
				 break;
			 default:
				 continue;
			}

			if (docopy) {
				if (resid < sizeof(struct in6_addr)) {
					/*
					 * We give up much more copy.
					 * Set the truncate flag and return.
					 */
					nni6->ni_flags |=
						NI_NODEADDR_FLAG_TRUNCATE;
					return(copied);
				}
				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 *)cp)->s6_addr16[1] = 0;
				cp += sizeof(struct in6_addr);
				resid -= sizeof(struct in6_addr);
				copied += sizeof(struct in6_addr);
			}
		}
		if (ifp0)	/* we need search only on the specified IF */
			break;
	}

	return(copied);
}

/*
 * 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 = 0;
	int plen;
	int type, code;
	struct ifnet *outif = NULL;
#ifdef COMPAT_RFC1885
	int mtu = IPV6_MMTU;
	struct sockaddr_in6 *sin6 = &icmp6_reflect_rt.ro_dst;
#endif

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

	/*
	 * If there are extra headers between IPv6 and ICMPv6, strip
	 * off that header first.
	 */
	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 hack for link-local addresses */
	if (IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst))
		ip6->ip6_dst.s6_addr16[1] =
			htons(m->m_pkthdr.rcvif->if_index);
	if (IN6_IS_ADDR_LINKLOCAL(&t))
		t.s6_addr16[1] = htons(m->m_pkthdr.rcvif->if_index);

#ifdef COMPAT_RFC1885
	/*
	 * xxx guess MTU
	 * RFC 1885 requires that echo reply should be truncated if it
	 * does not fit in with (return) path MTU, but the description was
	 * removed in the new spec.
	 */
	if (icmp6_reflect_rt.ro_rt == 0 ||
	    ! (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_dst))) {
		if (icmp6_reflect_rt.ro_rt) {
			icmp6_reflect_rt.ro_rt = 0;
		}
		bzero(sin6, sizeof(*sin6));
		sin6->sin6_family = PF_INET6;
		sin6->sin6_len = sizeof(struct sockaddr_in6);
		sin6->sin6_addr = ip6->ip6_dst;

		rtalloc((struct route *)&icmp6_reflect_rt.ro_rt);
	}

	if (icmp6_reflect_rt.ro_rt == 0)
		goto bad;

	if ((icmp6_reflect_rt.ro_rt->rt_flags & RTF_HOST)
	    && mtu < icmp6_reflect_rt.ro_rt->rt_ifp->if_mtu)
		mtu = icmp6_reflect_rt.ro_rt->rt_rmx.rmx_mtu;

	if (mtu < m->m_pkthdr.len) {
		plen -= (m->m_pkthdr.len - mtu);
		m_adj(m, mtu - m->m_pkthdr.len);
	}
#endif
	/*
	 * 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 would be VERY rare, but is possible
	 * (for example) when we encounter an error while forwarding procedure
	 * destined to a duplicated address of ours.
	 */
	for (ia = in6_ifaddr; ia; ia = ia->ia_next)
		if (IN6_ARE_ADDR_EQUAL(&t, &ia->ia_addr.sin6_addr) &&
		    (ia->ia6_flags & (IN6_IFF_ANYCAST|IN6_IFF_NOTREADY)) == 0) {
			src = &t;
			break;
		}
	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 ourseleves.
		 */
		src = &t;
	}

	if (src == 0)
		/*
		 * This case matches to multicasts, our anycast, or unicasts
		 * that we do not own. Select a source address which has the
		 * same scope.
		 * XXX: for (non link-local) multicast addresses, this might
		 * not be a good choice.
		 */
		if ((ia = in6_ifawithscope(m->m_pkthdr.rcvif, &t)) != 0)
			src = &IA6_SIN6(ia)->sin6_addr;

	if (src == 0)
		goto bad;

	ip6->ip6_src = *src;

	ip6->ip6_flow = 0;
	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
	ip6->ip6_vfc |= IPV6_VERSION;
	ip6->ip6_nxt = IPPROTO_ICMPV6;
	if (m->m_pkthdr.rcvif) {
		/* XXX: This may not be the outgoing interface */
		ip6->ip6_hlim = nd_ifinfo[m->m_pkthdr.rcvif->if_index].chlim;
	}

	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);
#ifdef IPSEC
	m->m_pkthdr.rcvif = NULL;
#endif /*IPSEC*/

#ifdef COMPAT_RFC1885
	ip6_output(m, NULL, &icmp6_reflect_rt, 0, NULL, &outif);
#else
	ip6_output(m, NULL, NULL, 0, NULL, &outif);
#endif
	if (outif)
		icmp6_ifoutstat_inc(outif, type, code);

	return;

 bad:
	m_freem(m);
	return;
}

void
icmp6_fasttimo()
{

	mld6_fasttimeo();
}

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)
	register 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;

	/* XXX if we are router, we don't update route by icmp6 redirect */
	if (ip6_forwarding)
		goto freeit;
	if (!icmp6_rediraccept)
		goto freeit;

#ifndef PULLDOWN_TEST
	IP6_EXTHDR_CHECK(m, off, icmp6len,);
	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_IS_ADDR_LINKLOCAL(&redtgt6))
		redtgt6.s6_addr16[1] = htons(ifp->if_index);
	if (IN6_IS_ADDR_LINKLOCAL(&reddst6))
		reddst6.s6_addr16[1] = htons(ifp->if_index);

	/* validation */
	if (!IN6_IS_ADDR_LINKLOCAL(&src6)) {
		log(LOG_ERR,
			"ICMP6 redirect sent from %s rejected; "
			"must be from linklocal\n", ip6_sprintf(&src6));
		goto freeit;
	}
	if (ip6->ip6_hlim != 255) {
		log(LOG_ERR,
			"ICMP6 redirect sent from %s rejected; "
			"hlim=%d (must be 255)\n",
			ip6_sprintf(&src6), ip6->ip6_hlim);
		goto freeit;
	}
    {
	/* 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((struct sockaddr *)&sin6, 0);
	if (rt) {
		gw6 = &(((struct sockaddr_in6 *)rt->rt_gateway)->sin6_addr);
		if (bcmp(&src6, gw6, sizeof(struct in6_addr)) != 0) {
			log(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));
			RTFREE(rt);
			goto freeit;
		}
	} else {
		log(LOG_ERR,
			"ICMP6 redirect rejected; "
			"no route found for redirect dst: %s\n",
			icmp6_redirect_diag(&src6, &reddst6, &redtgt6));
		goto freeit;
	}
	RTFREE(rt);
	rt = NULL;
    }
	if (IN6_IS_ADDR_MULTICAST(&reddst6)) {
		log(LOG_ERR,
			"ICMP6 redirect rejected; "
			"redirect dst must be unicast: %s\n",
			icmp6_redirect_diag(&src6, &reddst6, &redtgt6));
		goto freeit;
	}

	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) {
		log(LOG_ERR,
			"ICMP6 redirect rejected; "
			"neither router case nor onlink case: %s\n",
			icmp6_redirect_diag(&src6, &reddst6, &redtgt6));
		goto freeit;
	}
	/* validation passed */

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

	/* 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((struct sockaddr *)&sdst, (struct sockaddr *)&sgw,
			   (struct sockaddr *)NULL, RTF_GATEWAY | RTF_HOST,
			   (struct sockaddr *)&ssrc,
			   (struct rtentry **)NULL
			   );
	}
	/* finally update cached route in each socket via pfctlinput */
    {
	struct sockaddr_in6 sdst;
#if 1
#else
	struct ip6protosw *pr;
#endif

	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));
#if 1
	pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&sdst);
#else
	/*
	 * do not use pfctlinput() here, we have different prototype for
	 * xx_ctlinput() in ip6proto.
	 */
	for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
	     pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW;
	     pr++) {
		if (pr->pr_ctlinput) {
			(*pr->pr_ctlinput)(PRC_REDIRECT_HOST,
				(struct sockaddr *)&sdst, NULL, NULL, 0);
		}
	}
#endif
#ifdef IPSEC
	key_sa_routechange((struct sockaddr *)&sdst);
#endif
    }

 freeit:
	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;

	/* if we are not router, we don't send icmp6 redirect */
	if (!ip6_forwarding || ip6_accept_rtadv)
		goto fail;

	/* sanity check */
	if (!m0 || !rt || !(rt->rt_flags & RTF_UP) || !(ifp = rt->rt_ifp))
		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);
	if (nd6_is_addr_neighbor(&src_sa, ifp) == 0)
		goto fail;
	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);
	if (m && IPV6_MMTU >= MHLEN)
		MCLGET(m, M_DONTWAIT);
	if (!m)
		goto fail;
	maxlen = (m->m_flags & M_EXT) ? MCLBYTES : MHLEN;
	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;
		ifp_ll6 = &ia->ia_addr.sin6_addr;
	}

	/* get ip6 linklocal address for the router. */
	if (rt->rt_gateway && (rt->rt_flags & RTF_GATEWAY)) {
		struct sockaddr_in6 *sin6;
		sin6 = (struct sockaddr_in6 *)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));
	}

	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;

	rt_router = nd6_lookup(router_ll6, 0, ifp);
	if (!rt_router)
		goto nolladdropt;
	len = sizeof(*nd_opt) + ifp->if_addrlen;
	len = (len + 7) & ~7;	/*round by 8*/
	/* safety check */
	if (len + (p - (u_char *)ip6) > maxlen)
		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 *)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;
	}
    }
nolladdropt:;

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

	/* just to be safe */

    {
	/* 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;
    }

	if (IN6_IS_ADDR_LINKLOCAL(&sip6->ip6_src))
		sip6->ip6_src.s6_addr16[1] = 0;
	if (IN6_IS_ADDR_LINKLOCAL(&sip6->ip6_dst))
		sip6->ip6_dst.s6_addr16[1] = 0;
#if 0
	if (IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src))
		ip6->ip6_src.s6_addr16[1] = 0;
	if (IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst))
		ip6->ip6_dst.s6_addr16[1] = 0;
#endif
	if (IN6_IS_ADDR_LINKLOCAL(&nd_rd->nd_rd_target))
		nd_rd->nd_rd_target.s6_addr16[1] = 0;
	if (IN6_IS_ADDR_LINKLOCAL(&nd_rd->nd_rd_dst))
		nd_rd->nd_rd_dst.s6_addr16[1] = 0;

	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... */
#ifdef IPSEC
	m->m_pkthdr.rcvif = NULL;
#endif /*IPSEC*/
	ip6_output(m, NULL, NULL, 0, NULL, &outif);
	if (outif) {
		icmp6_ifstat_inc(outif, ifs6_out_msg);
		icmp6_ifstat_inc(outif, ifs6_out_redirect);
	}
	icmp6stat.icp6s_outhist[ND_REDIRECT]++;

	return;

fail:
	if (m)
		m_freem(m);
	if (m0)
		m_freem(m0);
}

/*
 * 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(dst, type, code)
	const struct in6_addr *dst;	/* not used at this moment */
	const int type;			/* not used at this moment */
	const int code;			/* not used at this moment */
{
	static struct timeval icmp6errratelim_last;

	/*
	 * ratecheck() returns true if it is okay to send.  We return
	 * true if it is not okay to send.
	 */
	return (ratecheck(&icmp6errratelim_last, &icmp6errratelim) == 0);
}

static struct rtentry *
icmp6_mtudisc_clone(dst)
	struct sockaddr *dst;
{
	struct rtentry *rt;
	int    error;

	rt = rtalloc1(dst, 1);
	if (rt == 0)
		return NULL;

	/* If we didn't get a host route, allocate one */
	if ((rt->rt_flags & RTF_HOST) == 0) {
		struct rtentry *nrt;

		error = rtrequest((int) RTM_ADD, dst,
		    (struct sockaddr *) rt->rt_gateway,
		    (struct sockaddr *) 0,
		    RTF_GATEWAY | RTF_HOST | RTF_DYNAMIC, &nrt);
		if (error) {
			rtfree(rt);
			rtfree(nrt);
			return NULL;
		}
		nrt->rt_rmx = rt->rt_rmx;
		rtfree(rt);
		rt = nrt;
	}
	error = rt_timer_add(rt, icmp6_mtudisc_timeout,
			icmp6_mtudisc_timeout_q);
	if (error) {
		rtfree(rt);
		return NULL;
	}

	return rt;	/* caller need to call rtfree() */
}

static void
icmp6_mtudisc_timeout(rt, r)
	struct rtentry *rt;
	struct rttimer *r;
{
	if (rt == NULL)
		panic("icmp6_mtudisc_timeout: bad route to timeout");
	if ((rt->rt_flags & (RTF_DYNAMIC | RTF_HOST)) ==
	    (RTF_DYNAMIC | RTF_HOST)) {
		rtrequest((int) RTM_DELETE, (struct sockaddr *)rt_key(rt),
		    rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
	} else {
		if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0) {
			rt->rt_rmx.rmx_mtu = 0;
		}
	}
}

#include <vm/vm.h>
#include <sys/sysctl.h>
int
icmp6_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
	int *name;
	u_int namelen;
	void *oldp;
	size_t *oldlenp;
	void *newp;
	size_t newlen;
{

	/* All sysctl names at this level are terminal. */
	if (namelen != 1)
		return ENOTDIR;

	switch (name[0]) {

	case ICMPV6CTL_REDIRACCEPT:
		return sysctl_int(oldp, oldlenp, newp, newlen,
				&icmp6_rediraccept);
	case ICMPV6CTL_REDIRTIMEOUT:
		return sysctl_int(oldp, oldlenp, newp, newlen,
				&icmp6_redirtimeout);
	case ICMPV6CTL_STATS:
		return sysctl_rdstruct(oldp, oldlenp, newp,
				&icmp6stat, sizeof(icmp6stat));
	case ICMPV6CTL_ERRRATELIMIT:
	    {
		int rate_usec, error, s;

		/*
		 * The sysctl specifies the rate in usec-between-icmp,
		 * so we must convert from/to a timeval.
		 */
		rate_usec = (icmp6errratelim.tv_sec * 1000000) +
		    icmp6errratelim.tv_usec;
		error = sysctl_int(oldp, oldlenp, newp, newlen, &rate_usec);
		if (error)
			return (error);
		if (rate_usec < 0)
			return (EINVAL);
		s = splsoftnet();
		icmp6errratelim.tv_sec = rate_usec / 1000000;
		icmp6errratelim.tv_usec = rate_usec % 1000000;
		splx(s);

		return (0);
	    }
	case ICMPV6CTL_ND6_PRUNE:
		return sysctl_int(oldp, oldlenp, newp, newlen, &nd6_prune);
	case ICMPV6CTL_ND6_DELAY:
		return sysctl_int(oldp, oldlenp, newp, newlen, &nd6_delay);
	case ICMPV6CTL_ND6_UMAXTRIES:
		return sysctl_int(oldp, oldlenp, newp, newlen, &nd6_umaxtries);
	case ICMPV6CTL_ND6_MMAXTRIES:
		return sysctl_int(oldp, oldlenp, newp, newlen, &nd6_mmaxtries);
	case ICMPV6CTL_ND6_USELOOPBACK:
		return sysctl_int(oldp, oldlenp, newp, newlen,
				&nd6_useloopback);
	case ICMPV6CTL_NODEINFO:
		return sysctl_int(oldp, oldlenp, newp, newlen, &icmp6_nodeinfo);
	default:
		return ENOPROTOOPT;
	}
	/* NOTREACHED */
}