FreeBSD/Linux Kernel Cross Reference
sys/netinet6/icmp6.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * 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.
     *
     *      $KAME: icmp6.c,v 1.211 2001/04/04 05:56:20 itojun Exp $
     */
    
    /*-
     * 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. 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/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #define MBUF_PRIVATE    /* XXXRW: Optimisation tries to avoid M_EXT mbufs */
    
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/domain.h>
    #include <sys/jail.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/proc.h>
    #include <sys/protosw.h>
    #include <sys/signalvar.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sx.h>
    #include <sys/syslog.h>
    #include <sys/systm.h>
    #include <sys/time.h>
    
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_dl.h>
    #include <net/if_llatbl.h>
    #include <net/if_types.h>
    #include <net/route.h>
    #include <net/route/route_ctl.h>
    #include <net/route/nhop.h>
    #include <net/vnet.h>
    
   #include <netinet/in.h>
   #include <netinet/in_pcb.h>
   #include <netinet/in_var.h>
   #include <netinet/ip6.h>
   #include <netinet/icmp6.h>
   #include <netinet/tcp_var.h>
   
   #include <netinet6/in6_fib.h>
   #include <netinet6/in6_ifattach.h>
   #include <netinet6/in6_pcb.h>
   #include <netinet6/ip6_var.h>
   #include <netinet6/scope6_var.h>
   #include <netinet6/mld6_var.h>
   #include <netinet6/nd6.h>
   #include <netinet6/send.h>
   
   extern ip6proto_ctlinput_t      *ip6_ctlprotox[];
   
   VNET_PCPUSTAT_DEFINE(struct icmp6stat, icmp6stat);
   VNET_PCPUSTAT_SYSINIT(icmp6stat);
   
   #ifdef VIMAGE
   VNET_PCPUSTAT_SYSUNINIT(icmp6stat);
   #endif /* VIMAGE */
   
   VNET_DECLARE(struct inpcbinfo, ripcbinfo);
   VNET_DECLARE(int, icmp6errppslim);
   VNET_DEFINE_STATIC(int, icmp6errpps_count) = 0;
   VNET_DEFINE_STATIC(struct timeval, icmp6errppslim_last);
   VNET_DECLARE(int, icmp6_nodeinfo);
   
   #define V_ripcbinfo                     VNET(ripcbinfo)
   #define V_icmp6errppslim                VNET(icmp6errppslim)
   #define V_icmp6errpps_count             VNET(icmp6errpps_count)
   #define V_icmp6errppslim_last           VNET(icmp6errppslim_last)
   #define V_icmp6_nodeinfo                VNET(icmp6_nodeinfo)
   
   static void icmp6_errcount(int, int);
   static int icmp6_rip6_input(struct mbuf **, int);
   static void icmp6_reflect(struct mbuf *, size_t);
   static const char *icmp6_redirect_diag(struct in6_addr *,
           struct in6_addr *, struct in6_addr *);
   static struct mbuf *ni6_input(struct mbuf *, int, struct prison *);
   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 mbuf *,
                             struct ifnet **, struct in6_addr *);
   static int ni6_store_addrs(struct icmp6_nodeinfo *, struct icmp6_nodeinfo *,
                                   struct ifnet *, int);
   static int icmp6_notify_error(struct mbuf **, int, int);
   
   /*
    * Kernel module interface for updating icmp6stat.  The argument is an index
    * into icmp6stat treated as an array of u_quad_t.  While this encodes the
    * general layout of icmp6stat into the caller, it doesn't encode its
    * location, so that future changes to add, for example, per-CPU stats
    * support won't cause binary compatibility problems for kernel modules.
    */
   void
   kmod_icmp6stat_inc(int statnum)
   {
   
           counter_u64_add(VNET(icmp6stat)[statnum], 1);
   }
   
   static void
   icmp6_errcount(int type, int code)
   {
           switch (type) {
           case ICMP6_DST_UNREACH:
                   switch (code) {
                   case ICMP6_DST_UNREACH_NOROUTE:
                           ICMP6STAT_INC(icp6s_odst_unreach_noroute);
                           return;
                   case ICMP6_DST_UNREACH_ADMIN:
                           ICMP6STAT_INC(icp6s_odst_unreach_admin);
                           return;
                   case ICMP6_DST_UNREACH_BEYONDSCOPE:
                           ICMP6STAT_INC(icp6s_odst_unreach_beyondscope);
                           return;
                   case ICMP6_DST_UNREACH_ADDR:
                           ICMP6STAT_INC(icp6s_odst_unreach_addr);
                           return;
                   case ICMP6_DST_UNREACH_NOPORT:
                           ICMP6STAT_INC(icp6s_odst_unreach_noport);
                           return;
                   }
                   break;
           case ICMP6_PACKET_TOO_BIG:
                   ICMP6STAT_INC(icp6s_opacket_too_big);
                   return;
           case ICMP6_TIME_EXCEEDED:
                   switch (code) {
                   case ICMP6_TIME_EXCEED_TRANSIT:
                           ICMP6STAT_INC(icp6s_otime_exceed_transit);
                           return;
                   case ICMP6_TIME_EXCEED_REASSEMBLY:
                           ICMP6STAT_INC(icp6s_otime_exceed_reassembly);
                           return;
                   }
                   break;
           case ICMP6_PARAM_PROB:
                   switch (code) {
                   case ICMP6_PARAMPROB_HEADER:
                           ICMP6STAT_INC(icp6s_oparamprob_header);
                           return;
                   case ICMP6_PARAMPROB_NEXTHEADER:
                           ICMP6STAT_INC(icp6s_oparamprob_nextheader);
                           return;
                   case ICMP6_PARAMPROB_OPTION:
                           ICMP6STAT_INC(icp6s_oparamprob_option);
                           return;
                   }
                   break;
           case ND_REDIRECT:
                   ICMP6STAT_INC(icp6s_oredirect);
                   return;
           }
           ICMP6STAT_INC(icp6s_ounknown);
   }
   
   /*
    * 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;
   
           if (m->m_len < sizeof(struct ip6_hdr)) {
                   m = m_pullup(m, sizeof(struct ip6_hdr));
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           return;
                   }
           }
           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;
           struct epoch_tracker et;
           u_int preplen;
           int off;
           int nxt;
   
           ICMP6STAT_INC(icp6s_error);
   
           /* count per-type-code statistics */
           icmp6_errcount(type, code);
   
   #ifdef M_DECRYPTED      /*not openbsd*/
           if (m->m_flags & M_DECRYPTED) {
                   ICMP6STAT_INC(icp6s_canterror);
                   goto freeit;
           }
   #endif
   
           if (m->m_len < sizeof(struct ip6_hdr)) {
                   m = m_pullup(m, sizeof(struct ip6_hdr));
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           return;
                   }
           }
           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 Packet 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;
   
                   if (m->m_len < off + sizeof(struct icmp6_hdr)) {
                           m = m_pullup(m, off + sizeof(struct icmp6_hdr));
                           if (m == NULL) {
                                   IP6STAT_INC(ip6s_exthdrtoolong);
                                   return;
                           }
                   }
                   oip6 = mtod(m, struct ip6_hdr *);
                   icp = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
   
                   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_INC(icp6s_canterror);
                           goto freeit;
                   } else {
                           /* ICMPv6 informational - send the error */
                   }
           } else {
                   /* non-ICMPv6 - send the error */
           }
   
           /* Finally, do rate limitation check. */
           if (icmp6_ratelimit(&oip6->ip6_src, type, code)) {
                   ICMP6STAT_INC(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_NOWAIT);        /* FIB is also copied over. */
           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);
   
           ICMP6STAT_INC(icp6s_outhist[type]);
           NET_EPOCH_ENTER(et);
           icmp6_reflect(m, sizeof(struct ip6_hdr)); /* header order: IPv6 - ICMPv6 */
           NET_EPOCH_EXIT(et);
   
           return;
   
     freeit:
           /*
            * If we can't tell whether or not we can generate ICMP6, free it.
            */
           m_freem(m);
   }
   
   int
   icmp6_errmap(const struct icmp6_hdr *icmp6)
   {
   
           switch (icmp6->icmp6_type) {
           case ICMP6_DST_UNREACH:
                   switch (icmp6->icmp6_code) {
                   case ICMP6_DST_UNREACH_NOROUTE:
                   case ICMP6_DST_UNREACH_ADDR:
                           return (EHOSTUNREACH);
                   case ICMP6_DST_UNREACH_NOPORT:
                   case ICMP6_DST_UNREACH_ADMIN:
                           return (ECONNREFUSED);
                   case ICMP6_DST_UNREACH_BEYONDSCOPE:
                           return (ENOPROTOOPT);
                   default:
                           return (0);     /* Shouldn't happen. */
                   }
           case ICMP6_PACKET_TOO_BIG:
                   return (EMSGSIZE);
           case ICMP6_TIME_EXCEEDED:
                   switch (icmp6->icmp6_code) {
                   case ICMP6_TIME_EXCEED_TRANSIT:
                           return (EHOSTUNREACH);
                   case ICMP6_TIME_EXCEED_REASSEMBLY:
                           return (0);
                   default:
                           return (0);     /* Shouldn't happen. */
                   }
           case ICMP6_PARAM_PROB:
                   switch (icmp6->icmp6_code) {
                   case ICMP6_PARAMPROB_NEXTHEADER:
                           return (ECONNREFUSED);
                   case ICMP6_PARAMPROB_HEADER:
                   case ICMP6_PARAMPROB_OPTION:
                           return (ENOPROTOOPT);
                   default:
                           return (0);     /* Shouldn't happen. */
                   }
           default:
                   return (0);
           }
   }
   
   /*
    * Process a received ICMP6 message.
    */
   int
   icmp6_input(struct mbuf **mp, int *offp, int proto)
   {
           struct mbuf *m, *n;
           struct ifnet *ifp;
           struct ip6_hdr *ip6, *nip6;
           struct icmp6_hdr *icmp6, *nicmp6;
           char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
           int code, error, icmp6len, ip6len, noff, off, sum;
   
           NET_EPOCH_ASSERT();
   
           m = *mp;
           off = *offp;
   
           if (m->m_len < off + sizeof(struct icmp6_hdr)) {
                   m = m_pullup(m, off + sizeof(struct icmp6_hdr));
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           *mp = m;
                           return (IPPROTO_DONE);
                   }
           }
   
           /*
            * Locate icmp6 structure in mbuf, and check
            * that not corrupted and of at least minimum length
            */
   
           icmp6len = m->m_pkthdr.len - off;
           if (icmp6len < sizeof(struct icmp6_hdr)) {
                   ICMP6STAT_INC(icp6s_tooshort);
                   goto freeit;
           }
   
           ip6 = mtod(m, struct ip6_hdr *);
           ifp = m->m_pkthdr.rcvif;
           /*
            * 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;
   
                   inm = in6m_lookup(ifp, &ip6->ip6_dst);
                   if (inm == NULL) {
                           IP6STAT_INC(ip6s_notmember);
                           in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
                           goto freeit;
                   }
           }
   
           /* Calculate the checksum. */
           icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
           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(ip6bufs, &ip6->ip6_src)));
                   ICMP6STAT_INC(icp6s_checksum);
                   goto freeit;
           }
   
           ICMP6STAT_INC(icp6s_inhist[icmp6->icmp6_type]);
           icmp6_ifstat_inc(ifp, ifs6_in_msg);
           if (icmp6->icmp6_type < ICMP6_INFOMSG_MASK)
                   icmp6_ifstat_inc(ifp, ifs6_in_error);
   
           ip6len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
           switch (icmp6->icmp6_type) {
           case ICMP6_DST_UNREACH:
                   icmp6_ifstat_inc(ifp, ifs6_in_dstunreach);
                   switch (code) {
                   case ICMP6_DST_UNREACH_ADMIN:
                           icmp6_ifstat_inc(ifp, ifs6_in_adminprohib);
                   case ICMP6_DST_UNREACH_NOROUTE:
                   case ICMP6_DST_UNREACH_ADDR:
                   case ICMP6_DST_UNREACH_BEYONDSCOPE:
                   case ICMP6_DST_UNREACH_NOPORT:
                           goto deliver;
                   default:
                           goto badcode;
                   }
           case ICMP6_PACKET_TOO_BIG:
                   icmp6_ifstat_inc(ifp, ifs6_in_pkttoobig);
                   /*
                    * Validation is made in icmp6_mtudisc_update.
                    * Updating the path MTU will be done after examining
                    * intermediate extension headers.
                    */
                   goto deliver;
           case ICMP6_TIME_EXCEEDED:
                   icmp6_ifstat_inc(ifp, ifs6_in_timeexceed);
                   switch (code) {
                   case ICMP6_TIME_EXCEED_TRANSIT:
                   case ICMP6_TIME_EXCEED_REASSEMBLY:
                           goto deliver;
                   default:
                           goto badcode;
                   }
           case ICMP6_PARAM_PROB:
                   icmp6_ifstat_inc(ifp, ifs6_in_paramprob);
                   switch (code) {
                   case ICMP6_PARAMPROB_NEXTHEADER:
                   case ICMP6_PARAMPROB_HEADER:
                   case ICMP6_PARAMPROB_OPTION:
                           goto deliver;
                   default:
                           goto badcode;
                   }
           case ICMP6_ECHO_REQUEST:
                   icmp6_ifstat_inc(ifp, ifs6_in_echo);
                   if (code != 0)
                           goto badcode;
                   if ((n = m_copym(m, 0, M_COPYALL, M_NOWAIT)) == NULL) {
                           /* Give up remote */
                           break;
                   }
                   if (!M_WRITABLE(n)
                    || n->m_len < off + sizeof(struct icmp6_hdr)) {
                           struct mbuf *n0 = n;
                           int n0len;
   
                           CTASSERT(sizeof(*nip6) + sizeof(*nicmp6) <= MHLEN);
                           n = m_gethdr(M_NOWAIT, n0->m_type);
                           if (n == NULL) {
                                   /* Give up remote */
                                   m_freem(n0);
                                   break;
                           }
   
                           m_move_pkthdr(n, n0);   /* FIB copied. */
                           n0len = n0->m_pkthdr.len;       /* save for use below */
                           /*
                            * 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);
                           /* new mbuf contains only ipv6+icmpv6 headers */
                           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));
                           /* recalculate complete packet size */
                           n->m_pkthdr.len = n0len + (noff - off);
                           n->m_next = n0;
                   } else {
                           if (n->m_len < off + sizeof(*nicmp6)) {
                                   n = m_pullup(n, off + sizeof(*nicmp6));
                                   if (n == NULL) {
                                           IP6STAT_INC(ip6s_exthdrtoolong);
                                           break;
                                   }
                           }
                           nicmp6 = (struct icmp6_hdr *)(mtod(n, caddr_t) + off);
                           noff = off;
                   }
                   if (n) {
                           nicmp6->icmp6_type = ICMP6_ECHO_REPLY;
                           nicmp6->icmp6_code = 0;
                           ICMP6STAT_INC(icp6s_reflect);
                           ICMP6STAT_INC(icp6s_outhist[ICMP6_ECHO_REPLY]);
                           icmp6_reflect(n, noff);
                   }
                   break;
   
           case ICMP6_ECHO_REPLY:
                   icmp6_ifstat_inc(ifp, ifs6_in_echoreply);
                   if (code != 0)
                           goto badcode;
                   break;
   
           case MLD_LISTENER_QUERY:
           case MLD_LISTENER_REPORT:
           case MLD_LISTENER_DONE:
           case MLDV2_LISTENER_REPORT:
                   /*
                    * Drop MLD traffic which is not link-local, has a hop limit
                    * of greater than 1 hop, or which does not have the
                    * IPv6 HBH Router Alert option.
                    * As IPv6 HBH options are stripped in ip6_input() we must
                    * check an mbuf header flag.
                    * XXX Should we also sanity check that these messages
                    * were directed to a link-local multicast prefix?
                    */
                   if ((ip6->ip6_hlim != 1) || (m->m_flags & M_RTALERT_MLD) == 0)
                           goto freeit;
                   if (mld_input(&m, off, icmp6len) != 0) {
                           *mp = NULL;
                           return (IPPROTO_DONE);
                   }
                   /* m stays. */
                   break;
   
           case ICMP6_WRUREQUEST:  /* ICMP6_FQDN_QUERY */
               {
                   enum { WRU, FQDN } mode;
                   struct prison *pr;
   
                   if (!V_icmp6_nodeinfo)
                           break;
   
                   if (icmp6len == sizeof(struct icmp6_hdr) + 4)
                           mode = WRU;
                   else if (icmp6len >= sizeof(struct icmp6_nodeinfo))
                           mode = FQDN;
                   else
                           goto badlen;
   
                   pr = NULL;
                   sx_slock(&allprison_lock);
                   TAILQ_FOREACH(pr, &allprison, pr_list)
                           if (pr->pr_vnet == ifp->if_vnet)
                                   break; 
                   sx_sunlock(&allprison_lock);
                   if (pr == NULL)
                           pr = curthread->td_ucred->cr_prison;
                   if (mode == FQDN) {
                           if (m->m_len < off + sizeof(struct icmp6_nodeinfo)) {
                                   m = m_pullup(m, off +
                                       sizeof(struct icmp6_nodeinfo));
                                   if (m == NULL) {
                                           IP6STAT_INC(ip6s_exthdrtoolong);
                                           *mp = m;
                                           return (IPPROTO_DONE);
                                   }
                           }
                           n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                           if (n)
                                   n = ni6_input(n, off, pr);
                           /* XXX meaningless if n == NULL */
                           noff = sizeof(struct ip6_hdr);
                   } else {
                           u_char *p;
                           int maxhlen, hlen;
   
                           /*
                            * XXX: this combination of flags is pointless,
                            * but should we keep this for compatibility?
                            */
                           if ((V_icmp6_nodeinfo & (ICMP6_NODEINFO_FQDNOK |
                               ICMP6_NODEINFO_TMPADDROK)) !=
                               (ICMP6_NODEINFO_FQDNOK | ICMP6_NODEINFO_TMPADDROK))
                                   break;
   
                           if (code != 0)
                                   goto badcode;
   
                           CTASSERT(sizeof(*nip6) + sizeof(*nicmp6) + 4 <= MHLEN);
                           n = m_gethdr(M_NOWAIT, m->m_type);
                           if (n == NULL) {
                                   /* Give up remote */
                                   break;
                           }
                           if (!m_dup_pkthdr(n, m, M_NOWAIT)) {
                                   /*
                                    * Previous code did a blind M_COPY_PKTHDR
                                    * and said "just for rcvif".  If true, then
                                    * we could tolerate the dup failing (due to
                                    * the deep copy of the tag chain).  For now
                                    * be conservative and just fail.
                                    */
                                   m_free(n);
                                   n = NULL;
                                   break;
                           }
                           /*
                            * 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);
   
                           maxhlen = M_TRAILINGSPACE(n) -
                               (sizeof(*nip6) + sizeof(*nicmp6) + 4);
                           mtx_lock(&pr->pr_mtx);
                           hlen = strlen(pr->pr_hostname);
                           if (maxhlen > hlen)
                                   maxhlen = hlen;
                           /* meaningless TTL */
                           bcopy(pr->pr_hostname, p + 4, maxhlen);
                           mtx_unlock(&pr->pr_mtx);
                           noff = sizeof(struct ip6_hdr);
                           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;
                   }
                   if (n) {
                           ICMP6STAT_INC(icp6s_reflect);
                           ICMP6STAT_INC(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(ifp, ifs6_in_routersolicit);
                   if (code != 0)
                           goto badcode;
                   if (icmp6len < sizeof(struct nd_router_solicit))
                           goto badlen;
                   if (send_sendso_input_hook != NULL) {
                           if (m->m_len < off + icmp6len) {
                                   m = m_pullup(m, off + icmp6len);
                                   if (m == NULL) {
                                           IP6STAT_INC(ip6s_exthdrtoolong);
                                           *mp = NULL;
                                           return (IPPROTO_DONE);
                                   }
                           }
                           error = send_sendso_input_hook(m, ifp, SND_IN, ip6len);
                           if (error == 0) {
                                   m = NULL;
                                   goto freeit;
                           }
                   }
                   n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                   nd6_rs_input(m, off, icmp6len);
                   m = n;
                   if (m == NULL)
                           goto freeit;
                   break;
   
           case ND_ROUTER_ADVERT:
                   icmp6_ifstat_inc(ifp, ifs6_in_routeradvert);
                   if (code != 0)
                           goto badcode;
                   if (icmp6len < sizeof(struct nd_router_advert))
                           goto badlen;
                   if (send_sendso_input_hook != NULL) {
                           error = send_sendso_input_hook(m, ifp, SND_IN, ip6len);
                           if (error == 0) {
                                   m = NULL;
                                   goto freeit;
                           }
                   }
                   n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                   nd6_ra_input(m, off, icmp6len);
                   m = n;
                   if (m == NULL)
                           goto freeit;
                   break;
   
           case ND_NEIGHBOR_SOLICIT:
                   icmp6_ifstat_inc(ifp, ifs6_in_neighborsolicit);
                   if (code != 0)
                           goto badcode;
                   if (icmp6len < sizeof(struct nd_neighbor_solicit))
                           goto badlen;
                   if (send_sendso_input_hook != NULL) {
                           error = send_sendso_input_hook(m, ifp, SND_IN, ip6len);
                           if (error == 0) {
                                   m = NULL;
                                   goto freeit;
                           }
                   }
                   n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                   nd6_ns_input(m, off, icmp6len);
                   m = n;
                   if (m == NULL)
                           goto freeit;
                   break;
   
           case ND_NEIGHBOR_ADVERT:
                   icmp6_ifstat_inc(ifp, ifs6_in_neighboradvert);
                   if (code != 0)
                           goto badcode;
                   if (icmp6len < sizeof(struct nd_neighbor_advert))
                           goto badlen;
                   if (send_sendso_input_hook != NULL) {
                           error = send_sendso_input_hook(m, ifp, SND_IN, ip6len);
                           if (error == 0) {
                                   m = NULL;
                                   goto freeit;
                           }
                   }
                   n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                   nd6_na_input(m, off, icmp6len);
                   m = n;
                   if (m == NULL)
                           goto freeit;
                   break;
   
           case ND_REDIRECT:
                   icmp6_ifstat_inc(ifp, ifs6_in_redirect);
                   if (code != 0)
                           goto badcode;
                   if (icmp6len < sizeof(struct nd_redirect))
                           goto badlen;
                   if (send_sendso_input_hook != NULL) {
                           error = send_sendso_input_hook(m, ifp, SND_IN, ip6len);
                           if (error == 0) {
                                   m = NULL;
                                   goto freeit;
                           }
                   }
                   n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                   icmp6_redirect_input(m, off);
                   m = n;
                   if (m == NULL)
                           goto freeit;
                   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:
                   nd6log((LOG_DEBUG,
                       "icmp6_input: unknown type %d(src=%s, dst=%s, ifid=%d)\n",
                       icmp6->icmp6_type, ip6_sprintf(ip6bufs, &ip6->ip6_src),
                       ip6_sprintf(ip6bufd, &ip6->ip6_dst),
                       ifp ? ifp->if_index : 0));
                   if (icmp6->icmp6_type < ICMP6_ECHO_REQUEST) {
                           /* ICMPv6 error: MUST deliver it by spec... */
                           goto deliver;
                   } else {
                           /* ICMPv6 informational: MUST not deliver */
                           break;
                   }
           deliver:
                   if (icmp6_notify_error(&m, off, icmp6len) != 0) {
                           /* In this case, m should've been freed. */
                           *mp = NULL;
                           return (IPPROTO_DONE);
                   }
                   break;
   
           badcode:
                   ICMP6STAT_INC(icp6s_badcode);
                   break;
   
           badlen:
                   ICMP6STAT_INC(icp6s_badlen);
                   break;
           }
   
           /* deliver the packet to appropriate sockets */
           icmp6_rip6_input(&m, *offp);
   
           *mp = m;
           return (IPPROTO_DONE);
   
    freeit:
           m_freem(m);
           *mp = NULL;
           return (IPPROTO_DONE);
   }
   
   static int
   icmp6_notify_error(struct mbuf **mp, int off, int icmp6len)
   {
           struct mbuf *m;
           struct icmp6_hdr *icmp6;
           struct ip6_hdr *eip6;
           u_int32_t notifymtu;
           struct sockaddr_in6 icmp6src, icmp6dst;
   
           m = *mp;
   
           if (icmp6len < sizeof(struct icmp6_hdr) + sizeof(struct ip6_hdr)) {
                   ICMP6STAT_INC(icp6s_tooshort);
                   goto freeit;
           }
   
           if (m->m_len < off + sizeof(*icmp6) + sizeof(struct ip6_hdr)) {
                   m = m_pullup(m, off + sizeof(*icmp6) + sizeof(struct ip6_hdr));
                   if (m == NULL) {
                           IP6STAT_INC(ip6s_exthdrtoolong);
                           *mp = m;
                           return (-1);
                   }
           }
           icmp6 = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
           eip6 = (struct ip6_hdr *)(icmp6 + 1);
           bzero(&icmp6dst, sizeof(icmp6dst));
   
           /* Detect the upper level protocol */
           {
                   u_int8_t nxt = eip6->ip6_nxt;
                   int eoff = off + sizeof(struct icmp6_hdr) +
                       sizeof(struct ip6_hdr);
                   struct ip6ctlparam ip6cp;
                   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:
                                   if (m->m_len < eoff + sizeof(struct ip6_ext)) {
                                           m = m_pullup(m, eoff +
                                               sizeof(struct ip6_ext));
                                           if (m == NULL) {
                                                   IP6STAT_INC(ip6s_exthdrtoolong);
                                                   *mp = m;
                                                   return (-1);
                                           }
                                   }
                                   eh = (struct ip6_ext *)
                                       (mtod(m, caddr_t) + eoff);
                                   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).
                                    */
                                   if (m->m_len < eoff + sizeof(*rth)) {
                                           m = m_pullup(m, eoff + sizeof(*rth));
                                           if (m == NULL) {
                                                   IP6STAT_INC(ip6s_exthdrtoolong);
                                                   *mp = m;
                                                   return (-1);
                                           }
                                   }
                                   rth = (struct ip6_rthdr *)
                                       (mtod(m, caddr_t) + eoff);
                                   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;
  
                                          if (m->m_len < eoff + rthlen) {
                                                  m = m_pullup(m, eoff + rthlen);
                                                  if (m == NULL) {
                                                          IP6STAT_INC(
                                                              ip6s_exthdrtoolong);
                                                          *mp = m;
                                                          return (-1);
                                                  }
                                          }
                                          rth0 = (struct ip6_rthdr0 *)
                                              (mtod(m, caddr_t) + eoff);
  
                                          /* just ignore a bogus header */
                                          if ((rth0->ip6r0_len % 2) == 0 &&
                                              (hops = rth0->ip6r0_len/2))
                                                  icmp6dst.sin6_addr = *((struct in6_addr *)(rth0 + 1) + (hops - 1));
                                  }
                                  eoff += rthlen;
                                  nxt = rth->ip6r_nxt;
                                  break;
                          case IPPROTO_FRAGMENT:
                                  if (m->m_len < eoff + sizeof(struct ip6_frag)) {
                                          m = m_pullup(m, eoff +
                                              sizeof(struct ip6_frag));
                                          if (m == NULL) {
                                                  IP6STAT_INC(ip6s_exthdrtoolong);
                                                  *mp = m;
                                                  return (-1);
                                          }
                                  }
                                  fh = (struct ip6_frag *)(mtod(m, caddr_t) +
                                      eoff);
                                  /*
                                   * 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:
                  icmp6 = (struct icmp6_hdr *)(mtod(m, caddr_t) + off);
  
                  /*
                   * 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);
  
                  icmp6dst.sin6_len = sizeof(struct sockaddr_in6);
                  icmp6dst.sin6_family = AF_INET6;
                  if (IN6_IS_ADDR_UNSPECIFIED(&icmp6dst.sin6_addr))
                          icmp6dst.sin6_addr = eip6->ip6_dst;
                  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);
  
                  ip6cp.ip6c_m = m;
                  ip6cp.ip6c_icmp6 = icmp6;
                  ip6cp.ip6c_ip6 = (struct ip6_hdr *)(icmp6 + 1);
                  ip6cp.ip6c_off = eoff;
                  ip6cp.ip6c_finaldst = &icmp6dst;
                  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*/
                  }
  
                  if (ip6_ctlprotox[nxt] != NULL)
                          ip6_ctlprotox[nxt](&ip6cp);
          }
          *mp = m;
          return (0);
  
    freeit:
          m_freem(m);
          *mp = NULL;
          return (-1);
  }
  
  void
  icmp6_mtudisc_update(struct ip6ctlparam *ip6cp, int validated)
  {
          struct in6_addr *dst = &ip6cp->ip6c_finaldst->sin6_addr;
          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 in_conninfo inc;
          uint32_t max_mtu;
  
  #if 0
          /*
           * RFC2460 section 5, last paragraph.
           * even though minimum link MTU for IPv6 is IPV6_MMTU,
           * we may see ICMPv6 too big with mtu < IPV6_MMTU
           * due to packet translator in the middle.
           * see ip6_output() and ip6_getpmtu() "alwaysfrag" case for
           * special handling.
           */
          if (mtu < IPV6_MMTU)
                  return;
  #endif
  
          /*
           * 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(&inc, sizeof(inc));
          inc.inc_fibnum = M_GETFIB(m);
          inc.inc_flags |= INC_ISIPV6;
          inc.inc6_faddr = *dst;
          if (in6_setscope(&inc.inc6_faddr, m->m_pkthdr.rcvif, NULL))
                  return;
  
          max_mtu = tcp_hc_getmtu(&inc);
          if (max_mtu == 0)
                  max_mtu = tcp_maxmtu6(&inc, NULL);
  
          if (mtu < max_mtu) {
                  tcp_hc_updatemtu(&inc, mtu);
                  ICMP6STAT_INC(icp6s_pmtuchg);
          }
  }
  
  /*
   * 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)
   */
  static struct mbuf *
  ni6_input(struct mbuf *m, int off, struct prison *pr)
  {
          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 in6_addr in6_subj; /* subject address */
          struct ip6_hdr *ip6;
          int oldfqdn = 0;        /* if 1, return pascal string (03 draft) */
          char *subj = NULL;
          struct in6_ifaddr *ia6 = NULL;
  
          ip6 = mtod(m, struct ip6_hdr *);
          ni6 = (struct icmp6_nodeinfo *)(mtod(m, caddr_t) + off);
  
          /*
           * 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 ((V_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 */
                  ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
                  if (ia6 == NULL)
                          goto bad; /* XXX impossible */
  
                  if ((ia6->ia6_flags & IN6_IFF_TEMPORARY) &&
                      !(V_icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK)) {
                          nd6log((LOG_DEBUG, "ni6_input: ignore node info to "
                                  "a temporary address in %s:%d",
                                 __FILE__, __LINE__));
                          goto bad;
                  }
          }
  
          /* 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_copydata(m, off + sizeof(struct icmp6_nodeinfo),
                              subjlen, (caddr_t)&in6_subj);
                          if (in6_setscope(&in6_subj, m->m_pkthdr.rcvif, NULL))
                                  goto bad;
  
                          subj = (char *)&in6_subj;
                          if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &in6_subj))
                                  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.
                           */
                          mtx_lock(&pr->pr_mtx);
                          n = ni6_nametodns(pr->pr_hostname,
                              strlen(pr->pr_hostname), 0);
                          mtx_unlock(&pr->pr_mtx);
                          if (!n || n->m_next || n->m_len == 0)
                                  goto bad;
                          if (m->m_len < off + sizeof(struct icmp6_nodeinfo) +
                              subjlen) {
                                  m = m_pullup(m, off +
                                      sizeof(struct icmp6_nodeinfo) + subjlen);
                                  if (m == NULL) {
                                          IP6STAT_INC(ip6s_exthdrtoolong);
                                          goto bad;
                                  }
                          }
                          /* ip6 possibly invalid but not used after. */
                          ni6 = (struct icmp6_nodeinfo *)(mtod(m, caddr_t) + off);
                          subj = (char *)(mtod(m, caddr_t) + off +
                              sizeof(struct icmp6_nodeinfo));
                          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 ((V_icmp6_nodeinfo & ICMP6_NODEINFO_FQDNOK) == 0)
                          goto bad;
                  break;
          case NI_QTYPE_NODEADDR:
          case NI_QTYPE_IPV4ADDR:
                  if ((V_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, m, &ifp, (struct in6_addr *)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. */
          if (replylen > MCLBYTES) {
                  /*
                   * XXX: should we try to allocate more? But MCLBYTES
                   * is probably much larger than IPV6_MMTU...
                   */
                  goto bad;
          }
          if (replylen > MHLEN)
                  n = m_getcl(M_NOWAIT, m->m_type, M_PKTHDR);
          else
                  n = m_gethdr(M_NOWAIT, m->m_type);
          if (n == NULL) {
                  m_freem(m);
                  return (NULL);
          }
          m_move_pkthdr(n, m); /* just for recvif and FIB */
          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 hostname?
                   */
                  mtx_lock(&pr->pr_mtx);
                  n->m_next = ni6_nametodns(pr->pr_hostname,
                      strlen(pr->pr_hostname), oldfqdn);
                  mtx_unlock(&pr->pr_mtx);
                  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);
          return (n);
  
    bad:
          m_freem(m);
          if (n)
                  m_freem(n);
          return (NULL);
  }
  
  /*
   * 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.
   *
   * old - return pascal string if non-zero
   */
  static struct mbuf *
  ni6_nametodns(const char *name, int namelen, int old)
  {
          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. */
          if (len > MLEN)
                  m = m_getcl(M_NOWAIT, MT_DATA, 0);
          else
                  m = m_get(M_NOWAIT, MT_DATA);
          if (m == NULL)
                  goto fail;
  
          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(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(struct icmp6_nodeinfo *ni6, struct mbuf *m, struct ifnet **ifpp,
      struct in6_addr *subj)
  {
          struct ifnet *ifp;
          struct in6_ifaddr *ifa6;
          struct ifaddr *ifa;
          int addrs = 0, addrsofif, iffound = 0;
          int niflags = ni6->ni_flags;
  
          NET_EPOCH_ASSERT();
  
          if ((niflags & NI_NODEADDR_FLAG_ALL) == 0) {
                  switch (ni6->ni_code) {
                  case ICMP6_NI_SUBJ_IPV6:
                          if (subj == NULL) /* must be impossible... */
                                  return (0);
                          break;
                  default:
                          /*
                           * XXX: we only support IPv6 subject address for
                           * this Qtype.
                           */
                          return (0);
                  }
          }
  
          CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  addrsofif = 0;
                  CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != AF_INET6)
                                  continue;
                          ifa6 = (struct in6_ifaddr *)ifa;
  
                          if ((niflags & NI_NODEADDR_FLAG_ALL) == 0 &&
                              IN6_ARE_ADDR_EQUAL(subj, &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)
                                          continue;
                                  break;
                          case IPV6_ADDR_SCOPE_SITELOCAL:
                                  if ((niflags & NI_NODEADDR_FLAG_SITELOCAL) == 0)
                                          continue;
                                  break;
                          case IPV6_ADDR_SCOPE_GLOBAL:
                                  if ((niflags & NI_NODEADDR_FLAG_GLOBAL) == 0)
                                          continue;
                                  break;
                          default:
                                  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)
                                  continue; /* we need only unicast addresses */
                          if ((ifa6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                              (V_icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK) == 0) {
                                  continue;
                          }
                          addrsofif++; /* count the address */
                  }
                  if (iffound) {
                          *ifpp = ifp;
                          return (addrsofif);
                  }
  
                  addrs += addrsofif;
          }
  
          return (addrs);
  }
  
  static int
  ni6_store_addrs(struct icmp6_nodeinfo *ni6, struct icmp6_nodeinfo *nni6,
      struct ifnet *ifp0, int resid)
  {
          struct ifnet *ifp;
          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;
  
          NET_EPOCH_ASSERT();
  
          if (ifp0 == NULL && !(niflags & NI_NODEADDR_FLAG_ALL))
                  return (0);     /* needless to copy */
  
          ifp = ifp0 ? ifp0 : CK_STAILQ_FIRST(&V_ifnet);
    again:
  
          for (; ifp; ifp = CK_STAILQ_NEXT(ifp, if_link)) {
                  CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != AF_INET6)
                                  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;
  
                                  continue;
                          } else if ((ifa6->ia6_flags & IN6_IFF_DEPRECATED) == 0 &&
                              allow_deprecated != 0)
                                  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)
                                          continue;
                                  break;
                          case IPV6_ADDR_SCOPE_SITELOCAL:
                                  if ((niflags & NI_NODEADDR_FLAG_SITELOCAL) == 0)
                                          continue;
                                  break;
                          case IPV6_ADDR_SCOPE_GLOBAL:
                                  if ((niflags & NI_NODEADDR_FLAG_GLOBAL) == 0)
                                          continue;
                                  break;
                          default:
                                  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)
                                  continue;
                          if ((ifa6->ia6_flags & IN6_IFF_TEMPORARY) != 0 &&
                              (V_icmp6_nodeinfo & ICMP6_NODEINFO_TMPADDROK) == 0) {
                                  continue;
                          }
  
                          /* now we can copy the address */
                          if (resid < sizeof(struct in6_addr) +
                              sizeof(u_int32_t)) {
                                  /*
                                   * We give up much more copy.
                                   * Set the truncate flag and return.
                                   */
                                  nni6->ni_flags |= NI_NODEADDR_FLAG_TRUNCATE;
                                  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)
                                  ltime = ND6_INFINITE_LIFETIME;
                          else {
                                  if (ifa6->ia6_lifetime.ia6t_expire >
                                      time_uptime)
                                          ltime = htonl(ifa6->ia6_lifetime.ia6t_expire - time_uptime);
                                  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));
                          in6_clearscope((struct in6_addr *)cp); /* XXX */
                          cp += sizeof(struct in6_addr);
  
                          resid -= (sizeof(struct in6_addr) + sizeof(u_int32_t));
                          copied += (sizeof(struct in6_addr) + sizeof(u_int32_t));
                  }
                  if (ifp0)       /* we need search only on the specified IF */
                          break;
          }
  
          if (allow_deprecated == 0 && ifp_dep != NULL) {
                  ifp = ifp_dep;
                  allow_deprecated = 1;
  
                  goto again;
          }
  
          return (copied);
  }
  
  static bool
  icmp6_rip6_match(const struct inpcb *inp, void *v)
  {
          struct ip6_hdr *ip6 = v;
  
          if ((inp->inp_vflag & INP_IPV6) == 0)
                  return (false);
          if (inp->inp_ip_p != IPPROTO_ICMPV6)
                  return (false);
          if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) &&
             !IN6_ARE_ADDR_EQUAL(&inp->in6p_laddr, &ip6->ip6_dst))
                  return (false);
          if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
             !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &ip6->ip6_src))
                  return (false);
          return (true);
  }
  
  /*
   * XXX almost dup'ed code with rip6_input.
   */
  static int
  icmp6_rip6_input(struct mbuf **mp, int off)
  {
          struct mbuf *n, *m = *mp;
          struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
          struct inpcb_iterator inpi = INP_ITERATOR(&V_ripcbinfo,
              INPLOOKUP_RLOCKPCB, icmp6_rip6_match, ip6);
          struct inpcb *inp;
          struct sockaddr_in6 fromsa;
          struct icmp6_hdr *icmp6;
          struct mbuf *opts = NULL;
          int delivered = 0;
  
          /* This is assumed to be safe; icmp6_input() does a pullup. */
          icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
  
          /*
           * XXX: the address may have embedded scope zone ID, which should be
           * hidden from applications.
           */
          bzero(&fromsa, sizeof(fromsa));
          fromsa.sin6_family = AF_INET6;
          fromsa.sin6_len = sizeof(struct sockaddr_in6);
          fromsa.sin6_addr = ip6->ip6_src;
          if (sa6_recoverscope(&fromsa)) {
                  m_freem(m);
                  *mp = NULL;
                  return (IPPROTO_DONE);
          }
  
          while ((inp = inp_next(&inpi)) != NULL) {
                  if (ICMP6_FILTER_WILLBLOCK(icmp6->icmp6_type,
                      inp->in6p_icmp6filt))
                          continue;
                  /*
                   * Recent network drivers tend to allocate a single
                   * mbuf cluster, rather than to make a couple of
                   * mbufs without clusters.  Also, since the IPv6 code
                   * path tries to avoid m_pullup(), it is highly
                   * probable that we still have an mbuf cluster here
                   * even though the necessary length can be stored in an
                   * mbuf's internal buffer.
                   * Meanwhile, the default size of the receive socket
                   * buffer for raw sockets is not so large.  This means
                   * the possibility of packet loss is relatively higher
                   * than before.  To avoid this scenario, we copy the
                   * received data to a separate mbuf that does not use
                   * a cluster, if possible.
                   * XXX: it is better to copy the data after stripping
                   * intermediate headers.
                   */
                  if ((m->m_flags & M_EXT) && m->m_next == NULL &&
                      m->m_len <= MHLEN) {
                          n = m_get(M_NOWAIT, m->m_type);
                          if (n != NULL) {
                                  if (m_dup_pkthdr(n, m, M_NOWAIT)) {
                                          bcopy(m->m_data, n->m_data, m->m_len);
                                          n->m_len = m->m_len;
                                  } else {
                                          m_free(n);
                                          n = NULL;
                                  }
                          }
                  } else
                          n = m_copym(m, 0, M_COPYALL, M_NOWAIT);
                  if (n == NULL)
                          continue;
                  if (inp->inp_flags & INP_CONTROLOPTS)
                          ip6_savecontrol(inp, n, &opts);
                  /* strip intermediate headers */
                  m_adj(n, off);
                  SOCKBUF_LOCK(&inp->inp_socket->so_rcv);
                  if (sbappendaddr_locked(&inp->inp_socket->so_rcv,
                      (struct sockaddr *)&fromsa, n, opts) == 0) {
                          soroverflow_locked(inp->inp_socket);
                          m_freem(n);
                          if (opts)
                                  m_freem(opts);
                  } else {
                          sorwakeup_locked(inp->inp_socket);
                          delivered++;
                  }
                  opts = NULL;
          }
          m_freem(m);
          *mp = NULL;
          if (delivered == 0)
                  IP6STAT_DEC(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.
   */
  static void
  icmp6_reflect(struct mbuf *m, size_t off)
  {
          struct in6_addr src6, *srcp;
          struct ip6_hdr *ip6;
          struct icmp6_hdr *icmp6;
          struct in6_ifaddr *ia = NULL;
          struct ifnet *outif = NULL;
          int plen;
          int type, code, hlim;
  
          /* 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_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.
           */
  #ifdef 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. */
          hlim = 0;
          srcp = 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.
           */
          if (!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                  ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
                  if (ia != NULL && !(ia->ia6_flags &
                      (IN6_IFF_ANYCAST|IN6_IFF_NOTREADY))) {
                          src6 = ia->ia_addr.sin6_addr;
                          srcp = &src6;
  
                          if (m->m_pkthdr.rcvif != NULL) {
                                  /* XXX: This may not be the outgoing interface */
                                  hlim = ND_IFINFO(m->m_pkthdr.rcvif)->chlim;
                          } else
                                  hlim = V_ip6_defhlim;
                  }
          }
  
          if (srcp == NULL) {
                  int error;
                  struct in6_addr dst6;
                  uint32_t scopeid;
  
                  /*
                   * 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.
                   */
                  in6_splitscope(&ip6->ip6_src, &dst6, &scopeid);
                  error = in6_selectsrc_addr(M_GETFIB(m), &dst6,
                      scopeid, NULL, &src6, &hlim);
  
                  if (error) {
                          char ip6buf[INET6_ADDRSTRLEN];
                          nd6log((LOG_DEBUG,
                              "icmp6_reflect: source can't be determined: "
                              "dst=%s, error=%d\n",
                              ip6_sprintf(ip6buf, &ip6->ip6_dst), error));
                          goto bad;
                  }
                  srcp = &src6;
          }
          /*
           * ip6_input() drops a packet if its src is multicast.
           * So, the src is never multicast.
           */
          ip6->ip6_dst = ip6->ip6_src;
          ip6->ip6_src = *srcp;
          ip6->ip6_flow = 0;
          ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
          ip6->ip6_vfc |= IPV6_VERSION;
          ip6->ip6_nxt = IPPROTO_ICMPV6;
          ip6->ip6_hlim = hlim;
  
          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);
          m->m_pkthdr.rcvif = NULL;
          ip6_output(m, NULL, NULL, 0, NULL, &outif, NULL);
          if (outif)
                  icmp6_ifoutstat_inc(outif, type, code);
  
          return;
  
   bad:
          m_freem(m);
          return;
  }
  
  static const char *
  icmp6_redirect_diag(struct in6_addr *src6, struct in6_addr *dst6,
      struct in6_addr *tgt6)
  {
          static char buf[1024];
          char ip6bufs[INET6_ADDRSTRLEN];
          char ip6bufd[INET6_ADDRSTRLEN];
          char ip6buft[INET6_ADDRSTRLEN];
          snprintf(buf, sizeof(buf), "(src=%s dst=%s tgt=%s)",
              ip6_sprintf(ip6bufs, src6), ip6_sprintf(ip6bufd, dst6),
              ip6_sprintf(ip6buft, tgt6));
          return buf;
  }
  
  void
  icmp6_redirect_input(struct mbuf *m, int off)
  {
          struct ifnet *ifp;
          struct ip6_hdr *ip6;
          struct nd_redirect *nd_rd;
          struct in6_addr src6, redtgt6, reddst6;
          union nd_opts ndopts;
          char ip6buf[INET6_ADDRSTRLEN];
          char *lladdr;
          int icmp6len, is_onlink, is_router, lladdrlen;
  
          M_ASSERTPKTHDR(m);
          KASSERT(m->m_pkthdr.rcvif != NULL, ("%s: no rcvif", __func__));
  
          /* XXX if we are router, we don't update route by icmp6 redirect */
          if (V_ip6_forwarding)
                  goto freeit;
          if (!V_icmp6_rediraccept)
                  goto freeit;
  
          /* RFC 6980: Nodes MUST silently ignore fragments */
          if(m->m_flags & M_FRAGMENTED)
                  goto freeit;
  
          ip6 = mtod(m, struct ip6_hdr *);
          icmp6len = ntohs(ip6->ip6_plen);
          if (m->m_len < off + icmp6len) {
                  m = m_pullup(m, off + icmp6len);
                  if (m == NULL) {
                          IP6STAT_INC(ip6s_exthdrtoolong);
                          return;
                  }
          }
          ip6 = mtod(m, struct ip6_hdr *);
          nd_rd = (struct nd_redirect *)((caddr_t)ip6 + off);
  
          ifp = m->m_pkthdr.rcvif;
          redtgt6 = nd_rd->nd_rd_target;
          reddst6 = nd_rd->nd_rd_dst;
  
          if (in6_setscope(&redtgt6, ifp, NULL) ||
              in6_setscope(&reddst6, ifp, NULL)) {
                  goto freeit;
          }
  
          /* validation */
          src6 = ip6->ip6_src;
          if (!IN6_IS_ADDR_LINKLOCAL(&src6)) {
                  nd6log((LOG_ERR,
                      "ICMP6 redirect sent from %s rejected; "
                      "must be from linklocal\n",
                      ip6_sprintf(ip6buf, &src6)));
                  goto bad;
          }
          if (__predict_false(ip6->ip6_hlim != 255)) {
                  ICMP6STAT_INC(icp6s_invlhlim);
                  nd6log((LOG_ERR,
                      "ICMP6 redirect sent from %s rejected; "
                      "hlim=%d (must be 255)\n",
                      ip6_sprintf(ip6buf, &src6), ip6->ip6_hlim));
                  goto bad;
          }
      {
          /* ip6->ip6_src must be equal to gw for icmp6->icmp6_reddst */
          struct nhop_object *nh;
          struct in6_addr kdst;
          uint32_t scopeid;
  
          in6_splitscope(&reddst6, &kdst, &scopeid);
          NET_EPOCH_ASSERT();
          nh = fib6_lookup(ifp->if_fib, &kdst, scopeid, 0, 0);
          if (nh != NULL) {
                  struct in6_addr nh_addr;
                  nh_addr = ifatoia6(nh->nh_ifa)->ia_addr.sin6_addr;
                  if ((nh->nh_flags & NHF_GATEWAY) == 0) {
                          nd6log((LOG_ERR,
                              "ICMP6 redirect rejected; no route "
                              "with inet6 gateway found for redirect dst: %s\n",
                              icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                          goto bad;
                  }
  
                  /*
                   * Embed scope zone id into next hop address.
                   */
                  nh_addr = nh->gw6_sa.sin6_addr;
  
                  if (IN6_ARE_ADDR_EQUAL(&src6, &nh_addr) == 0) {
                          nd6log((LOG_ERR,
                              "ICMP6 redirect rejected; "
                              "not equal to gw-for-src=%s (must be same): "
                              "%s\n",
                              ip6_sprintf(ip6buf, &nh_addr),
                              icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                          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;
          }
      }
          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;
          }
  
          icmp6len -= sizeof(*nd_rd);
          nd6_option_init(nd_rd + 1, icmp6len, &ndopts);
          if (nd6_options(&ndopts) < 0) {
                  nd6log((LOG_INFO, "%s: invalid ND option, rejected: %s\n",
                      __func__, icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                  /* nd6_options have incremented stats */
                  goto freeit;
          }
  
          lladdr = NULL;
          lladdrlen = 0;
          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 (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
                  nd6log((LOG_INFO, "%s: lladdrlen mismatch for %s "
                      "(if %d, icmp6 packet %d): %s\n",
                      __func__, ip6_sprintf(ip6buf, &redtgt6),
                      ifp->if_addrlen, lladdrlen - 2,
                      icmp6_redirect_diag(&src6, &reddst6, &redtgt6)));
                  goto bad;
          }
  
          /* Validation passed. */
  
          /* RFC 2461 8.3 */
          nd6_cache_lladdr(ifp, &redtgt6, lladdr, lladdrlen, ND_REDIRECT,
              is_onlink ? ND_REDIRECT_ONLINK : ND_REDIRECT_ROUTER);
  
          /*
           * Install a gateway route in the better-router case or an interface
           * route in the on-link-destination case.
           */
          {
                  struct sockaddr_in6 sdst;
                  struct sockaddr_in6 sgw;
                  struct sockaddr_in6 ssrc;
                  struct sockaddr *gw;
                  int rt_flags;
                  u_int fibnum;
  
                  bzero(&sdst, sizeof(sdst));
                  bzero(&ssrc, sizeof(ssrc));
                  sdst.sin6_family = ssrc.sin6_family = AF_INET6;
                  sdst.sin6_len = ssrc.sin6_len = sizeof(struct sockaddr_in6);
                  bcopy(&reddst6, &sdst.sin6_addr, sizeof(struct in6_addr));
                  bcopy(&src6, &ssrc.sin6_addr, sizeof(struct in6_addr));
                  rt_flags = 0;
                  if (is_router) {
                          bzero(&sgw, sizeof(sgw));
                          sgw.sin6_family = AF_INET6;
                          sgw.sin6_len = sizeof(struct sockaddr_in6);
                          bcopy(&redtgt6, &sgw.sin6_addr,
                                  sizeof(struct in6_addr));
                          gw = (struct sockaddr *)&sgw;
                          rt_flags |= RTF_GATEWAY;
                  } else
                          gw = ifp->if_addr->ifa_addr;
                  for (fibnum = 0; fibnum < rt_numfibs; fibnum++)
                          rib_add_redirect(fibnum, (struct sockaddr *)&sdst, gw,
                              (struct sockaddr *)&ssrc, ifp, rt_flags,
                              V_icmp6_redirtimeout);
          }
  
   freeit:
          m_freem(m);
          return;
  
   bad:
          ICMP6STAT_INC(icp6s_badredirect);
          m_freem(m);
  }
  
  void
  icmp6_redirect_output(struct mbuf *m0, struct nhop_object *nh)
  {
          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 m_tag *mtag;
          struct ip6_hdr *ip6;    /* m as struct ip6_hdr */
          struct nd_redirect *nd_rd;
          struct llentry *ln = NULL;
          size_t maxlen;
          u_char *p;
          struct ifnet *outif = NULL;
          struct sockaddr_in6 src_sa;
  
          icmp6_errcount(ND_REDIRECT, 0);
  
          /* if we are not router, we don't send icmp6 redirect */
          if (!V_ip6_forwarding)
                  goto fail;
  
          /* sanity check */
          if (!m0 || !nh || !(NH_IS_VALID(nh)) || !(ifp = nh->nh_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;
          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
          m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
          if (m == NULL)
                  goto fail;
          M_SETFIB(m, M_GETFIB(m0));
          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;
                  ifp_ll6 = &ia->ia_addr.sin6_addr;
                  /* XXXRW: reference released prematurely. */
                  ifa_free(&ia->ia_ifa);
          }
  
          /* get ip6 linklocal address for the router. */
          if (nh->nh_flags & NHF_GATEWAY) {
                  struct sockaddr_in6 *sin6;
                  sin6 = &nh->gw6_sa;
                  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 (nh->nh_flags & NHF_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 */
                  int len;
                  struct nd_opt_hdr *nd_opt;
                  char *lladdr;
  
                  ln = nd6_lookup(router_ll6, LLE_SF(AF_INET6,  0), ifp);
                  if (ln == NULL)
                          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 (ln->la_flags & LLE_VALID) {
                          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(ln->ll_addr, lladdr, ifp->if_addrlen);
                          p += len;
                  }
          }
  nolladdropt:
          if (ln != NULL)
                  LLE_RUNLOCK(ln);
                  
          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", __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_tag_delete_chain(m0, NULL);
                  m0->m_flags &= ~M_PKTHDR;
                  m->m_next = m0;
                  m->m_pkthdr.len = m->m_len + m0->m_len;
                  m0 = NULL;
          }
  noredhdropt:;
          if (m0) {
                  m_freem(m0);
                  m0 = NULL;
          }
  
          /* 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));
  
          if (send_sendso_input_hook != NULL) {
                  mtag = m_tag_get(PACKET_TAG_ND_OUTGOING, sizeof(unsigned short),
                          M_NOWAIT);
                  if (mtag == NULL)
                          goto fail;
                  *(unsigned short *)(mtag + 1) = nd_rd->nd_rd_type;
                  m_tag_prepend(m, mtag);
          }
  
          /* send the packet to outside... */
          ip6_output(m, NULL, NULL, 0, NULL, &outif, NULL);
          if (outif) {
                  icmp6_ifstat_inc(outif, ifs6_out_msg);
                  icmp6_ifstat_inc(outif, ifs6_out_redirect);
          }
          ICMP6STAT_INC(icp6s_outhist[ND_REDIRECT]);
  
          return;
  
  fail:
          if (m)
                  m_freem(m);
          if (m0)
                  m_freem(m0);
  }
  
  /*
   * ICMPv6 socket option processing.
   */
  int
  icmp6_ctloutput(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 ic6f;
  
                          if (optlen != sizeof(ic6f)) {
                                  error = EMSGSIZE;
                                  break;
                          }
                          error = sooptcopyin(sopt, &ic6f, optlen, optlen);
                          if (error == 0) {
                                  INP_WLOCK(inp);
                                  *inp->in6p_icmp6filt = ic6f;
                                  INP_WUNLOCK(inp);
                          }
                          break;
                      }
  
                  default:
                          error = ENOPROTOOPT;
                          break;
                  }
                  break;
  
          case PRCO_GETOPT:
                  switch (optname) {
                  case ICMP6_FILTER:
                      {
                          struct icmp6_filter ic6f;
  
                          INP_RLOCK(inp);
                          ic6f = *inp->in6p_icmp6filt;
                          INP_RUNLOCK(inp);
                          error = sooptcopyout(sopt, &ic6f, sizeof(ic6f));
                          break;
                      }
  
                  default:
                          error = ENOPROTOOPT;
                          break;
                  }
                  break;
          }
  
          return (error);
  }
  
  /*
   * 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?
   *
   * dst - not used at this moment
   * type - not used at this moment
   * code - not used at this moment
   */
  int
  icmp6_ratelimit(const struct in6_addr *dst, const int type,
      const int code)
  {
          int ret;
  
          ret = 0;        /* okay to send */
  
          /* PPS limit */
          if (!ppsratecheck(&V_icmp6errppslim_last, &V_icmp6errpps_count,
              V_icmp6errppslim)) {
                  /* The packet is subject to rate limit */
                  ret++;
          }
  
          return ret;
  }

Cache object: 1db2569cd79d0c26e8e7bb3420346893