The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_forward.c

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    1 /*      $FreeBSD: releng/5.4/sys/netinet6/ip6_forward.c 141090 2005-01-31 23:27:04Z imp $       */
    2 /*      $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $    */
    3 
    4 /*-
    5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 
   33 #include "opt_ip6fw.h"
   34 #include "opt_inet.h"
   35 #include "opt_inet6.h"
   36 #include "opt_ipsec.h"
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/malloc.h>
   41 #include <sys/mbuf.h>
   42 #include <sys/domain.h>
   43 #include <sys/protosw.h>
   44 #include <sys/socket.h>
   45 #include <sys/errno.h>
   46 #include <sys/time.h>
   47 #include <sys/kernel.h>
   48 #include <sys/syslog.h>
   49 
   50 #include <net/if.h>
   51 #include <net/route.h>
   52 #include <net/pfil.h>
   53 
   54 #include <netinet/in.h>
   55 #include <netinet/in_var.h>
   56 #include <netinet/in_systm.h>
   57 #include <netinet/ip.h>
   58 #include <netinet/ip_var.h>
   59 #include <netinet6/in6_var.h>
   60 #include <netinet/ip6.h>
   61 #include <netinet6/ip6_var.h>
   62 #include <netinet/icmp6.h>
   63 #include <netinet6/nd6.h>
   64 
   65 #include <netinet/in_pcb.h>
   66 
   67 #ifdef IPSEC
   68 #include <netinet6/ipsec.h>
   69 #ifdef INET6
   70 #include <netinet6/ipsec6.h>
   71 #endif
   72 #include <netkey/key.h>
   73 #endif /* IPSEC */
   74 
   75 #ifdef FAST_IPSEC
   76 #include <netipsec/ipsec.h>
   77 #include <netipsec/ipsec6.h>
   78 #include <netipsec/key.h>
   79 #define IPSEC
   80 #endif /* FAST_IPSEC */
   81 
   82 #include <netinet6/ip6_fw.h>
   83 
   84 #include <net/net_osdep.h>
   85 
   86 #include <netinet6/ip6protosw.h>
   87 
   88 struct  route_in6 ip6_forward_rt;
   89 
   90 /*
   91  * Forward a packet.  If some error occurs return the sender
   92  * an icmp packet.  Note we can't always generate a meaningful
   93  * icmp message because icmp doesn't have a large enough repertoire
   94  * of codes and types.
   95  *
   96  * If not forwarding, just drop the packet.  This could be confusing
   97  * if ipforwarding was zero but some routing protocol was advancing
   98  * us as a gateway to somewhere.  However, we must let the routing
   99  * protocol deal with that.
  100  *
  101  */
  102 
  103 void
  104 ip6_forward(m, srcrt)
  105         struct mbuf *m;
  106         int srcrt;
  107 {
  108         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  109         struct sockaddr_in6 *dst = NULL;
  110         struct rtentry *rt = NULL;
  111         int error, type = 0, code = 0;
  112         struct mbuf *mcopy = NULL;
  113         struct ifnet *origifp;  /* maybe unnecessary */
  114         u_int32_t srczone, dstzone;
  115 #ifdef IPSEC
  116         struct secpolicy *sp = NULL;
  117         int ipsecrt = 0;
  118 #endif
  119 
  120 #ifdef IPSEC
  121         /*
  122          * Check AH/ESP integrity.
  123          */
  124         /*
  125          * Don't increment ip6s_cantforward because this is the check
  126          * before forwarding packet actually.
  127          */
  128         if (ipsec6_in_reject(m, NULL)) {
  129 #if !defined(FAST_IPSEC)
  130                 ipsec6stat.in_polvio++;
  131 #endif
  132                 m_freem(m);
  133                 return;
  134         }
  135 #endif /* IPSEC */
  136 
  137         /*
  138          * Do not forward packets to multicast destination (should be handled
  139          * by ip6_mforward().
  140          * Do not forward packets with unspecified source.  It was discussed
  141          * in July 2000, on the ipngwg mailing list.
  142          */
  143         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
  144             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
  145             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
  146                 ip6stat.ip6s_cantforward++;
  147                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  148                 if (ip6_log_time + ip6_log_interval < time_second) {
  149                         ip6_log_time = time_second;
  150                         log(LOG_DEBUG,
  151                             "cannot forward "
  152                             "from %s to %s nxt %d received on %s\n",
  153                             ip6_sprintf(&ip6->ip6_src),
  154                             ip6_sprintf(&ip6->ip6_dst),
  155                             ip6->ip6_nxt,
  156                             if_name(m->m_pkthdr.rcvif));
  157                 }
  158                 m_freem(m);
  159                 return;
  160         }
  161 
  162         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
  163                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  164                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
  165                                 ICMP6_TIME_EXCEED_TRANSIT, 0);
  166                 return;
  167         }
  168         ip6->ip6_hlim -= IPV6_HLIMDEC;
  169 
  170         /*
  171          * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
  172          * size of IPv6 + ICMPv6 headers) bytes of the packet in case
  173          * we need to generate an ICMP6 message to the src.
  174          * Thanks to M_EXT, in most cases copy will not occur.
  175          *
  176          * It is important to save it before IPsec processing as IPsec
  177          * processing may modify the mbuf.
  178          */
  179         mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
  180 
  181 #ifdef IPSEC
  182         /* get a security policy for this packet */
  183         sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
  184             IP_FORWARDING, &error);
  185         if (sp == NULL) {
  186                 ipsec6stat.out_inval++;
  187                 ip6stat.ip6s_cantforward++;
  188                 if (mcopy) {
  189 #if 0
  190                         /* XXX: what icmp ? */
  191 #else
  192                         m_freem(mcopy);
  193 #endif
  194                 }
  195                 m_freem(m);
  196                 return;
  197         }
  198 
  199         error = 0;
  200 
  201         /* check policy */
  202         switch (sp->policy) {
  203         case IPSEC_POLICY_DISCARD:
  204                 /*
  205                  * This packet is just discarded.
  206                  */
  207                 ipsec6stat.out_polvio++;
  208                 ip6stat.ip6s_cantforward++;
  209                 key_freesp(sp);
  210                 if (mcopy) {
  211 #if 0
  212                         /* XXX: what icmp ? */
  213 #else
  214                         m_freem(mcopy);
  215 #endif
  216                 }
  217                 m_freem(m);
  218                 return;
  219 
  220         case IPSEC_POLICY_BYPASS:
  221         case IPSEC_POLICY_NONE:
  222                 /* no need to do IPsec. */
  223                 key_freesp(sp);
  224                 goto skip_ipsec;
  225 
  226         case IPSEC_POLICY_IPSEC:
  227                 if (sp->req == NULL) {
  228                         /* XXX should be panic ? */
  229                         printf("ip6_forward: No IPsec request specified.\n");
  230                         ip6stat.ip6s_cantforward++;
  231                         key_freesp(sp);
  232                         if (mcopy) {
  233 #if 0
  234                                 /* XXX: what icmp ? */
  235 #else
  236                                 m_freem(mcopy);
  237 #endif
  238                         }
  239                         m_freem(m);
  240                         return;
  241                 }
  242                 /* do IPsec */
  243                 break;
  244 
  245         case IPSEC_POLICY_ENTRUST:
  246         default:
  247                 /* should be panic ?? */
  248                 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
  249                 key_freesp(sp);
  250                 goto skip_ipsec;
  251         }
  252 
  253     {
  254         struct ipsecrequest *isr = NULL;
  255         struct ipsec_output_state state;
  256 
  257         /*
  258          * when the kernel forwards a packet, it is not proper to apply
  259          * IPsec transport mode to the packet is not proper.  this check
  260          * avoid from this.
  261          * at present, if there is even a transport mode SA request in the
  262          * security policy, the kernel does not apply IPsec to the packet.
  263          * this check is not enough because the following case is valid.
  264          *      ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
  265          */
  266         for (isr = sp->req; isr; isr = isr->next) {
  267                 if (isr->saidx.mode == IPSEC_MODE_ANY)
  268                         goto doipsectunnel;
  269                 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
  270                         goto doipsectunnel;
  271         }
  272 
  273         /*
  274          * if there's no need for tunnel mode IPsec, skip.
  275          */
  276         if (!isr)
  277                 goto skip_ipsec;
  278 
  279     doipsectunnel:
  280         /*
  281          * All the extension headers will become inaccessible
  282          * (since they can be encrypted).
  283          * Don't panic, we need no more updates to extension headers
  284          * on inner IPv6 packet (since they are now encapsulated).
  285          *
  286          * IPv6 [ESP|AH] IPv6 [extension headers] payload
  287          */
  288         bzero(&state, sizeof(state));
  289         state.m = m;
  290         state.ro = NULL;        /* update at ipsec6_output_tunnel() */
  291         state.dst = NULL;       /* update at ipsec6_output_tunnel() */
  292 
  293         error = ipsec6_output_tunnel(&state, sp, 0);
  294 
  295         m = state.m;
  296         key_freesp(sp);
  297 
  298         if (error) {
  299                 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
  300                 switch (error) {
  301                 case EHOSTUNREACH:
  302                 case ENETUNREACH:
  303                 case EMSGSIZE:
  304                 case ENOBUFS:
  305                 case ENOMEM:
  306                         break;
  307                 default:
  308                         printf("ip6_output (ipsec): error code %d\n", error);
  309                         /* FALLTHROUGH */
  310                 case ENOENT:
  311                         /* don't show these error codes to the user */
  312                         break;
  313                 }
  314                 ip6stat.ip6s_cantforward++;
  315                 if (mcopy) {
  316 #if 0
  317                         /* XXX: what icmp ? */
  318 #else
  319                         m_freem(mcopy);
  320 #endif
  321                 }
  322                 m_freem(m);
  323                 return;
  324         }
  325 
  326         if (ip6 != mtod(m, struct ip6_hdr *)) {
  327                 /*
  328                  * now tunnel mode headers are added.  we are originating
  329                  * packet instead of forwarding the packet.
  330                  */
  331                 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
  332                     NULL);
  333                 goto freecopy;
  334         }
  335 
  336         /* adjust pointer */
  337         dst = (struct sockaddr_in6 *)state.dst;
  338         rt = state.ro ? state.ro->ro_rt : NULL;
  339         if (dst != NULL && rt != NULL)
  340                 ipsecrt = 1;
  341     }
  342     skip_ipsec:
  343 #endif /* IPSEC */
  344 
  345 #ifdef IPSEC
  346         if (ipsecrt)
  347                 goto skip_routing;
  348 #endif
  349 
  350         dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
  351         if (!srcrt) {
  352                 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
  353                 if (ip6_forward_rt.ro_rt == 0 ||
  354                     (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
  355                         if (ip6_forward_rt.ro_rt) {
  356                                 RTFREE(ip6_forward_rt.ro_rt);
  357                                 ip6_forward_rt.ro_rt = 0;
  358                         }
  359 
  360                         /* this probably fails but give it a try again */
  361                         rtalloc((struct route *)&ip6_forward_rt);
  362                 }
  363 
  364                 if (ip6_forward_rt.ro_rt == 0) {
  365                         ip6stat.ip6s_noroute++;
  366                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
  367                         if (mcopy) {
  368                                 icmp6_error(mcopy, ICMP6_DST_UNREACH,
  369                                             ICMP6_DST_UNREACH_NOROUTE, 0);
  370                         }
  371                         m_freem(m);
  372                         return;
  373                 }
  374         } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
  375                    !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
  376                 if (ip6_forward_rt.ro_rt) {
  377                         RTFREE(ip6_forward_rt.ro_rt);
  378                         ip6_forward_rt.ro_rt = 0;
  379                 }
  380                 bzero(dst, sizeof(*dst));
  381                 dst->sin6_len = sizeof(struct sockaddr_in6);
  382                 dst->sin6_family = AF_INET6;
  383                 dst->sin6_addr = ip6->ip6_dst;
  384 
  385                 rtalloc((struct route *)&ip6_forward_rt);
  386                 if (ip6_forward_rt.ro_rt == 0) {
  387                         ip6stat.ip6s_noroute++;
  388                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
  389                         if (mcopy) {
  390                                 icmp6_error(mcopy, ICMP6_DST_UNREACH,
  391                                             ICMP6_DST_UNREACH_NOROUTE, 0);
  392                         }
  393                         m_freem(m);
  394                         return;
  395                 }
  396         }
  397         rt = ip6_forward_rt.ro_rt;
  398 #ifdef IPSEC
  399     skip_routing:;
  400 #endif
  401 
  402         /*
  403          * Scope check: if a packet can't be delivered to its destination
  404          * for the reason that the destination is beyond the scope of the
  405          * source address, discard the packet and return an icmp6 destination
  406          * unreachable error with Code 2 (beyond scope of source address).
  407          * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
  408          */
  409         if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
  410             in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone)) {
  411                 /* XXX: this should not happen */
  412                 ip6stat.ip6s_cantforward++;
  413                 ip6stat.ip6s_badscope++;
  414                 m_freem(m);
  415                 return;
  416         }
  417         if (srczone != dstzone
  418 #ifdef IPSEC
  419             && !ipsecrt
  420 #endif
  421             ) {
  422                 ip6stat.ip6s_cantforward++;
  423                 ip6stat.ip6s_badscope++;
  424                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
  425 
  426                 if (ip6_log_time + ip6_log_interval < time_second) {
  427                         ip6_log_time = time_second;
  428                         log(LOG_DEBUG,
  429                             "cannot forward "
  430                             "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  431                             ip6_sprintf(&ip6->ip6_src),
  432                             ip6_sprintf(&ip6->ip6_dst),
  433                             ip6->ip6_nxt,
  434                             if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
  435                 }
  436                 if (mcopy)
  437                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  438                                     ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
  439                 m_freem(m);
  440                 return;
  441         }
  442 
  443         if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
  444                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
  445                 if (mcopy) {
  446                         u_long mtu;
  447 #ifdef IPSEC
  448                         struct secpolicy *sp;
  449                         int ipsecerror;
  450                         size_t ipsechdrsiz;
  451 #endif
  452 
  453                         mtu = IN6_LINKMTU(rt->rt_ifp);
  454 #ifdef IPSEC
  455                         /*
  456                          * When we do IPsec tunnel ingress, we need to play
  457                          * with the link value (decrement IPsec header size
  458                          * from mtu value).  The code is much simpler than v4
  459                          * case, as we have the outgoing interface for
  460                          * encapsulated packet as "rt->rt_ifp".
  461                          */
  462                         sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
  463                                 IP_FORWARDING, &ipsecerror);
  464                         if (sp) {
  465                                 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
  466                                         IPSEC_DIR_OUTBOUND, NULL);
  467                                 if (ipsechdrsiz < mtu)
  468                                         mtu -= ipsechdrsiz;
  469                         }
  470 
  471                         /*
  472                          * if mtu becomes less than minimum MTU,
  473                          * tell minimum MTU (and I'll need to fragment it).
  474                          */
  475                         if (mtu < IPV6_MMTU)
  476                                 mtu = IPV6_MMTU;
  477 #endif
  478                         icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
  479                 }
  480                 m_freem(m);
  481                 return;
  482         }
  483 
  484         if (rt->rt_flags & RTF_GATEWAY)
  485                 dst = (struct sockaddr_in6 *)rt->rt_gateway;
  486 
  487         /*
  488          * If we are to forward the packet using the same interface
  489          * as one we got the packet from, perhaps we should send a redirect
  490          * to sender to shortcut a hop.
  491          * Only send redirect if source is sending directly to us,
  492          * and if packet was not source routed (or has any options).
  493          * Also, don't send redirect if forwarding using a route
  494          * modified by a redirect.
  495          */
  496         if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
  497 #ifdef IPSEC
  498             !ipsecrt &&
  499 #endif
  500             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
  501                 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
  502                         /*
  503                          * If the incoming interface is equal to the outgoing
  504                          * one, and the link attached to the interface is
  505                          * point-to-point, then it will be highly probable
  506                          * that a routing loop occurs. Thus, we immediately
  507                          * drop the packet and send an ICMPv6 error message.
  508                          *
  509                          * type/code is based on suggestion by Rich Draves.
  510                          * not sure if it is the best pick.
  511                          */
  512                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  513                                     ICMP6_DST_UNREACH_ADDR, 0);
  514                         m_freem(m);
  515                         return;
  516                 }
  517                 type = ND_REDIRECT;
  518         }
  519 
  520         /*
  521          * Check with the firewall...
  522          */
  523         if (ip6_fw_enable && ip6_fw_chk_ptr) {
  524                 u_short port = 0;
  525                 /* If ipfw says divert, we have to just drop packet */
  526                 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
  527                         m_freem(m);
  528                         goto freecopy;
  529                 }
  530                 if (!m)
  531                         goto freecopy;
  532         }
  533 
  534         /*
  535          * Fake scoped addresses. Note that even link-local source or
  536          * destinaion can appear, if the originating node just sends the
  537          * packet to us (without address resolution for the destination).
  538          * Since both icmp6_error and icmp6_redirect_output fill the embedded
  539          * link identifiers, we can do this stuff after making a copy for
  540          * returning an error.
  541          */
  542         if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
  543                 /*
  544                  * See corresponding comments in ip6_output.
  545                  * XXX: but is it possible that ip6_forward() sends a packet
  546                  *      to a loopback interface? I don't think so, and thus
  547                  *      I bark here. (jinmei@kame.net)
  548                  * XXX: it is common to route invalid packets to loopback.
  549                  *      also, the codepath will be visited on use of ::1 in
  550                  *      rthdr. (itojun)
  551                  */
  552 #if 1
  553                 if (0)
  554 #else
  555                 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
  556 #endif
  557                 {
  558                         printf("ip6_forward: outgoing interface is loopback. "
  559                                "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  560                                ip6_sprintf(&ip6->ip6_src),
  561                                ip6_sprintf(&ip6->ip6_dst),
  562                                ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
  563                                if_name(rt->rt_ifp));
  564                 }
  565 
  566                 /* we can just use rcvif in forwarding. */
  567                 origifp = m->m_pkthdr.rcvif;
  568         }
  569         else
  570                 origifp = rt->rt_ifp;
  571         /*
  572          * clear embedded scope identifiers if necessary.
  573          * in6_clearscope will touch the addresses only when necessary.
  574          */
  575         in6_clearscope(&ip6->ip6_src);
  576         in6_clearscope(&ip6->ip6_dst);
  577 
  578         /* Jump over all PFIL processing if hooks are not active. */
  579         if (inet6_pfil_hook.ph_busy_count == -1)
  580                 goto pass;
  581 
  582         /* Run through list of hooks for output packets. */
  583         error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
  584         if (error != 0)
  585                 goto senderr;
  586         if (m == NULL)
  587                 goto freecopy;
  588         ip6 = mtod(m, struct ip6_hdr *);
  589 
  590 pass:
  591         error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
  592         if (error) {
  593                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
  594                 ip6stat.ip6s_cantforward++;
  595         } else {
  596                 ip6stat.ip6s_forward++;
  597                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
  598                 if (type)
  599                         ip6stat.ip6s_redirectsent++;
  600                 else {
  601                         if (mcopy)
  602                                 goto freecopy;
  603                 }
  604         }
  605 
  606 senderr:
  607         if (mcopy == NULL)
  608                 return;
  609         switch (error) {
  610         case 0:
  611                 if (type == ND_REDIRECT) {
  612                         icmp6_redirect_output(mcopy, rt);
  613                         return;
  614                 }
  615                 goto freecopy;
  616 
  617         case EMSGSIZE:
  618                 /* xxx MTU is constant in PPP? */
  619                 goto freecopy;
  620 
  621         case ENOBUFS:
  622                 /* Tell source to slow down like source quench in IP? */
  623                 goto freecopy;
  624 
  625         case ENETUNREACH:       /* shouldn't happen, checked above */
  626         case EHOSTUNREACH:
  627         case ENETDOWN:
  628         case EHOSTDOWN:
  629         default:
  630                 type = ICMP6_DST_UNREACH;
  631                 code = ICMP6_DST_UNREACH_ADDR;
  632                 break;
  633         }
  634         icmp6_error(mcopy, type, code, 0);
  635         return;
  636 
  637  freecopy:
  638         m_freem(mcopy);
  639         return;
  640 }

Cache object: 2e97bb18b70cd6b56e736f158c103830


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