The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_input.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
   30  */
   31 
   32 /*-
   33  * Copyright (c) 1982, 1986, 1988, 1993
   34  *      The Regents of the University of California.  All rights reserved.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice, this list of conditions and the following disclaimer.
   41  * 2. Redistributions in binary form must reproduce the above copyright
   42  *    notice, this list of conditions and the following disclaimer in the
   43  *    documentation and/or other materials provided with the distribution.
   44  * 4. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD: stable/8/sys/netinet6/ip6_input.c 264875 2014-04-24 11:14:17Z ae $");
   65 
   66 #include "opt_inet.h"
   67 #include "opt_inet6.h"
   68 #include "opt_ipsec.h"
   69 
   70 #include <sys/param.h>
   71 #include <sys/systm.h>
   72 #include <sys/malloc.h>
   73 #include <sys/mbuf.h>
   74 #include <sys/proc.h>
   75 #include <sys/domain.h>
   76 #include <sys/protosw.h>
   77 #include <sys/socket.h>
   78 #include <sys/socketvar.h>
   79 #include <sys/errno.h>
   80 #include <sys/time.h>
   81 #include <sys/kernel.h>
   82 #include <sys/syslog.h>
   83 
   84 #include <net/if.h>
   85 #include <net/if_types.h>
   86 #include <net/if_dl.h>
   87 #include <net/route.h>
   88 #include <net/netisr.h>
   89 #include <net/pfil.h>
   90 #include <net/vnet.h>
   91 
   92 #include <netinet/in.h>
   93 #include <netinet/in_systm.h>
   94 #include <net/if_llatbl.h>
   95 #ifdef INET
   96 #include <netinet/ip.h>
   97 #include <netinet/ip_icmp.h>
   98 #endif /* INET */
   99 #include <netinet/ip6.h>
  100 #include <netinet6/in6_var.h>
  101 #include <netinet6/ip6_var.h>
  102 #include <netinet/in_pcb.h>
  103 #include <netinet/icmp6.h>
  104 #include <netinet6/scope6_var.h>
  105 #include <netinet6/in6_ifattach.h>
  106 #include <netinet6/nd6.h>
  107 
  108 #ifdef IPSEC
  109 #include <netipsec/ipsec.h>
  110 #include <netinet6/ip6_ipsec.h>
  111 #include <netipsec/ipsec6.h>
  112 #endif /* IPSEC */
  113 
  114 #include <netinet6/ip6protosw.h>
  115 
  116 extern struct domain inet6domain;
  117 
  118 u_char ip6_protox[IPPROTO_MAX];
  119 VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
  120 
  121 static struct netisr_handler ip6_nh = {
  122         .nh_name = "ip6",
  123         .nh_handler = ip6_input,
  124         .nh_proto = NETISR_IPV6,
  125         .nh_policy = NETISR_POLICY_FLOW,
  126 };
  127 
  128 VNET_DECLARE(struct callout, in6_tmpaddrtimer_ch);
  129 #define V_in6_tmpaddrtimer_ch           VNET(in6_tmpaddrtimer_ch)
  130 
  131 VNET_DEFINE(struct pfil_head, inet6_pfil_hook);
  132 
  133 VNET_DEFINE(struct ip6stat, ip6stat);
  134 
  135 struct rwlock in6_ifaddr_lock;
  136 RW_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
  137 
  138 static void ip6_init2(void *);
  139 static struct ip6aux *ip6_setdstifaddr(struct mbuf *, struct in6_ifaddr *);
  140 static int ip6_hopopts_input(u_int32_t *, u_int32_t *, struct mbuf **, int *);
  141 #ifdef PULLDOWN_TEST
  142 static struct mbuf *ip6_pullexthdr(struct mbuf *, size_t, int);
  143 #endif
  144 
  145 /*
  146  * IP6 initialization: fill in IP6 protocol switch table.
  147  * All protocols not implemented in kernel go to raw IP6 protocol handler.
  148  */
  149 void
  150 ip6_init(void)
  151 {
  152         struct ip6protosw *pr;
  153         int i;
  154 
  155         TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
  156             &V_ip6_auto_linklocal);
  157 
  158         TAILQ_INIT(&V_in6_ifaddrhead);
  159 
  160         /* Initialize packet filter hooks. */
  161         V_inet6_pfil_hook.ph_type = PFIL_TYPE_AF;
  162         V_inet6_pfil_hook.ph_af = AF_INET6;
  163         if ((i = pfil_head_register(&V_inet6_pfil_hook)) != 0)
  164                 printf("%s: WARNING: unable to register pfil hook, "
  165                         "error %d\n", __func__, i);
  166 
  167         scope6_init();
  168         addrsel_policy_init();
  169         nd6_init();
  170         frag6_init();
  171 
  172         V_ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
  173 
  174         /* Skip global initialization stuff for non-default instances. */
  175         if (!IS_DEFAULT_VNET(curvnet))
  176                 return;
  177 
  178 #ifdef DIAGNOSTIC
  179         if (sizeof(struct protosw) != sizeof(struct ip6protosw))
  180                 panic("sizeof(protosw) != sizeof(ip6protosw)");
  181 #endif
  182         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  183         if (pr == NULL)
  184                 panic("ip6_init");
  185 
  186         /* Initialize the entire ip6_protox[] array to IPPROTO_RAW. */
  187         for (i = 0; i < IPPROTO_MAX; i++)
  188                 ip6_protox[i] = pr - inet6sw;
  189         /*
  190          * Cycle through IP protocols and put them into the appropriate place
  191          * in ip6_protox[].
  192          */
  193         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  194             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++)
  195                 if (pr->pr_domain->dom_family == PF_INET6 &&
  196                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  197                         /* Be careful to only index valid IP protocols. */
  198                         if (pr->pr_protocol < IPPROTO_MAX)
  199                                 ip6_protox[pr->pr_protocol] = pr - inet6sw;
  200                 }
  201 
  202         netisr_register(&ip6_nh);
  203 }
  204 
  205 /*
  206  * The protocol to be inserted into ip6_protox[] must be already registered
  207  * in inet6sw[], either statically or through pf_proto_register().
  208  */
  209 int
  210 ip6proto_register(short ip6proto)
  211 {
  212         struct ip6protosw *pr;
  213 
  214         /* Sanity checks. */
  215         if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
  216                 return (EPROTONOSUPPORT);
  217 
  218         /*
  219          * The protocol slot must not be occupied by another protocol
  220          * already.  An index pointing to IPPROTO_RAW is unused.
  221          */
  222         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  223         if (pr == NULL)
  224                 return (EPFNOSUPPORT);
  225         if (ip6_protox[ip6proto] != pr - inet6sw)       /* IPPROTO_RAW */
  226                 return (EEXIST);
  227 
  228         /*
  229          * Find the protocol position in inet6sw[] and set the index.
  230          */
  231         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  232             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++) {
  233                 if (pr->pr_domain->dom_family == PF_INET6 &&
  234                     pr->pr_protocol && pr->pr_protocol == ip6proto) {
  235                         ip6_protox[pr->pr_protocol] = pr - inet6sw;
  236                         return (0);
  237                 }
  238         }
  239         return (EPROTONOSUPPORT);
  240 }
  241 
  242 int
  243 ip6proto_unregister(short ip6proto)
  244 {
  245         struct ip6protosw *pr;
  246 
  247         /* Sanity checks. */
  248         if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
  249                 return (EPROTONOSUPPORT);
  250 
  251         /* Check if the protocol was indeed registered. */
  252         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  253         if (pr == NULL)
  254                 return (EPFNOSUPPORT);
  255         if (ip6_protox[ip6proto] == pr - inet6sw)       /* IPPROTO_RAW */
  256                 return (ENOENT);
  257 
  258         /* Reset the protocol slot to IPPROTO_RAW. */
  259         ip6_protox[ip6proto] = pr - inet6sw;
  260         return (0);
  261 }
  262 
  263 #ifdef VIMAGE
  264 void
  265 ip6_destroy()
  266 {
  267 
  268         nd6_destroy();
  269         callout_drain(&V_in6_tmpaddrtimer_ch);
  270 }
  271 #endif
  272 
  273 static int
  274 ip6_init2_vnet(const void *unused __unused)
  275 {
  276 
  277         /* nd6_timer_init */
  278         callout_init(&V_nd6_timer_ch, 0);
  279         callout_reset(&V_nd6_timer_ch, hz, nd6_timer, curvnet);
  280 
  281         /* timer for regeneranation of temporary addresses randomize ID */
  282         callout_init(&V_in6_tmpaddrtimer_ch, 0);
  283         callout_reset(&V_in6_tmpaddrtimer_ch,
  284                       (V_ip6_temp_preferred_lifetime - V_ip6_desync_factor -
  285                        V_ip6_temp_regen_advance) * hz,
  286                       in6_tmpaddrtimer, curvnet);
  287 
  288         return (0);
  289 }
  290 
  291 static void
  292 ip6_init2(void *dummy)
  293 {
  294 
  295         ip6_init2_vnet(NULL);
  296 }
  297 
  298 /* cheat */
  299 /* This must be after route_init(), which is now SI_ORDER_THIRD */
  300 SYSINIT(netinet6init2, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ip6_init2, NULL);
  301 
  302 void
  303 ip6_input(struct mbuf *m)
  304 {
  305         struct ip6_hdr *ip6;
  306         int off = sizeof(struct ip6_hdr), nest;
  307         u_int32_t plen;
  308         u_int32_t rtalert = ~0;
  309         int nxt, ours = 0;
  310         struct ifnet *deliverifp = NULL, *ifp = NULL;
  311         struct in6_addr odst;
  312         struct route_in6 rin6;
  313         int srcrt = 0;
  314         struct llentry *lle = NULL;
  315         struct sockaddr_in6 dst6, *dst;
  316 
  317         bzero(&rin6, sizeof(struct route_in6));
  318 #ifdef IPSEC
  319         /*
  320          * should the inner packet be considered authentic?
  321          * see comment in ah4_input().
  322          * NB: m cannot be NULL when passed to the input routine
  323          */
  324 
  325         m->m_flags &= ~M_AUTHIPHDR;
  326         m->m_flags &= ~M_AUTHIPDGM;
  327 
  328 #endif /* IPSEC */
  329 
  330         /*
  331          * make sure we don't have onion peering information into m_tag.
  332          */
  333         ip6_delaux(m);
  334 
  335         /*
  336          * mbuf statistics
  337          */
  338         if (m->m_flags & M_EXT) {
  339                 if (m->m_next)
  340                         V_ip6stat.ip6s_mext2m++;
  341                 else
  342                         V_ip6stat.ip6s_mext1++;
  343         } else {
  344 #define M2MMAX  (sizeof(V_ip6stat.ip6s_m2m)/sizeof(V_ip6stat.ip6s_m2m[0]))
  345                 if (m->m_next) {
  346                         if (m->m_flags & M_LOOP) {
  347                                 V_ip6stat.ip6s_m2m[V_loif->if_index]++;
  348                         } else if (m->m_pkthdr.rcvif->if_index < M2MMAX)
  349                                 V_ip6stat.ip6s_m2m[m->m_pkthdr.rcvif->if_index]++;
  350                         else
  351                                 V_ip6stat.ip6s_m2m[0]++;
  352                 } else
  353                         V_ip6stat.ip6s_m1++;
  354 #undef M2MMAX
  355         }
  356 
  357         /* drop the packet if IPv6 operation is disabled on the IF */
  358         if ((ND_IFINFO(m->m_pkthdr.rcvif)->flags & ND6_IFF_IFDISABLED)) {
  359                 m_freem(m);
  360                 return;
  361         }
  362 
  363         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_receive);
  364         V_ip6stat.ip6s_total++;
  365 
  366 #ifndef PULLDOWN_TEST
  367         /*
  368          * L2 bridge code and some other code can return mbuf chain
  369          * that does not conform to KAME requirement.  too bad.
  370          * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
  371          */
  372         if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
  373                 struct mbuf *n;
  374 
  375                 MGETHDR(n, M_DONTWAIT, MT_HEADER);
  376                 if (n)
  377                         M_MOVE_PKTHDR(n, m);
  378                 if (n && n->m_pkthdr.len > MHLEN) {
  379                         MCLGET(n, M_DONTWAIT);
  380                         if ((n->m_flags & M_EXT) == 0) {
  381                                 m_freem(n);
  382                                 n = NULL;
  383                         }
  384                 }
  385                 if (n == NULL) {
  386                         m_freem(m);
  387                         return; /* ENOBUFS */
  388                 }
  389 
  390                 m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
  391                 n->m_len = n->m_pkthdr.len;
  392                 m_freem(m);
  393                 m = n;
  394         }
  395         IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), /* nothing */);
  396 #endif
  397 
  398         if (m->m_len < sizeof(struct ip6_hdr)) {
  399                 struct ifnet *inifp;
  400                 inifp = m->m_pkthdr.rcvif;
  401                 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
  402                         V_ip6stat.ip6s_toosmall++;
  403                         in6_ifstat_inc(inifp, ifs6_in_hdrerr);
  404                         return;
  405                 }
  406         }
  407 
  408         ip6 = mtod(m, struct ip6_hdr *);
  409 
  410         if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
  411                 V_ip6stat.ip6s_badvers++;
  412                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  413                 goto bad;
  414         }
  415 
  416         V_ip6stat.ip6s_nxthist[ip6->ip6_nxt]++;
  417 
  418         /*
  419          * Check against address spoofing/corruption.
  420          */
  421         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
  422             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
  423                 /*
  424                  * XXX: "badscope" is not very suitable for a multicast source.
  425                  */
  426                 V_ip6stat.ip6s_badscope++;
  427                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  428                 goto bad;
  429         }
  430         if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
  431             !(m->m_flags & M_LOOP)) {
  432                 /*
  433                  * In this case, the packet should come from the loopback
  434                  * interface.  However, we cannot just check the if_flags,
  435                  * because ip6_mloopback() passes the "actual" interface
  436                  * as the outgoing/incoming interface.
  437                  */
  438                 V_ip6stat.ip6s_badscope++;
  439                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  440                 goto bad;
  441         }
  442 
  443 #ifdef ALTQ
  444         if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
  445                 /* packet is dropped by traffic conditioner */
  446                 return;
  447         }
  448 #endif
  449         /*
  450          * The following check is not documented in specs.  A malicious
  451          * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
  452          * and bypass security checks (act as if it was from 127.0.0.1 by using
  453          * IPv6 src ::ffff:127.0.0.1).  Be cautious.
  454          *
  455          * This check chokes if we are in an SIIT cloud.  As none of BSDs
  456          * support IPv4-less kernel compilation, we cannot support SIIT
  457          * environment at all.  So, it makes more sense for us to reject any
  458          * malicious packets for non-SIIT environment, than try to do a
  459          * partial support for SIIT environment.
  460          */
  461         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  462             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  463                 V_ip6stat.ip6s_badscope++;
  464                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  465                 goto bad;
  466         }
  467 #if 0
  468         /*
  469          * Reject packets with IPv4 compatible addresses (auto tunnel).
  470          *
  471          * The code forbids auto tunnel relay case in RFC1933 (the check is
  472          * stronger than RFC1933).  We may want to re-enable it if mech-xx
  473          * is revised to forbid relaying case.
  474          */
  475         if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
  476             IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
  477                 V_ip6stat.ip6s_badscope++;
  478                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  479                 goto bad;
  480         }
  481 #endif
  482 
  483         /*
  484          * Run through list of hooks for input packets.
  485          *
  486          * NB: Beware of the destination address changing
  487          *     (e.g. by NAT rewriting).  When this happens,
  488          *     tell ip6_forward to do the right thing.
  489          */
  490         odst = ip6->ip6_dst;
  491 
  492         /* Jump over all PFIL processing if hooks are not active. */
  493         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  494                 goto passin;
  495 
  496         if (pfil_run_hooks(&V_inet6_pfil_hook, &m,
  497             m->m_pkthdr.rcvif, PFIL_IN, NULL))
  498                 return;
  499         if (m == NULL)                  /* consumed by filter */
  500                 return;
  501         ip6 = mtod(m, struct ip6_hdr *);
  502         srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
  503 
  504 passin:
  505         /*
  506          * Disambiguate address scope zones (if there is ambiguity).
  507          * We first make sure that the original source or destination address
  508          * is not in our internal form for scoped addresses.  Such addresses
  509          * are not necessarily invalid spec-wise, but we cannot accept them due
  510          * to the usage conflict.
  511          * in6_setscope() then also checks and rejects the cases where src or
  512          * dst are the loopback address and the receiving interface
  513          * is not loopback.
  514          */
  515         if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
  516                 V_ip6stat.ip6s_badscope++; /* XXX */
  517                 goto bad;
  518         }
  519         if (in6_setscope(&ip6->ip6_src, m->m_pkthdr.rcvif, NULL) ||
  520             in6_setscope(&ip6->ip6_dst, m->m_pkthdr.rcvif, NULL)) {
  521                 V_ip6stat.ip6s_badscope++;
  522                 goto bad;
  523         }
  524 
  525         /*
  526          * Multicast check. Assume packet is for us to avoid
  527          * prematurely taking locks.
  528          */
  529         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  530                 ours = 1;
  531                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mcast);
  532                 deliverifp = m->m_pkthdr.rcvif;
  533                 goto hbhcheck;
  534         }
  535 
  536         /*
  537          *  Unicast check
  538          */
  539 
  540         bzero(&dst6, sizeof(dst6));
  541         dst6.sin6_family = AF_INET6;
  542         dst6.sin6_len = sizeof(struct sockaddr_in6);
  543         dst6.sin6_addr = ip6->ip6_dst;
  544         ifp = m->m_pkthdr.rcvif;
  545         IF_AFDATA_RLOCK(ifp);
  546         lle = lla_lookup(LLTABLE6(ifp), 0,
  547              (struct sockaddr *)&dst6);
  548         IF_AFDATA_RUNLOCK(ifp);
  549         if ((lle != NULL) && (lle->la_flags & LLE_IFADDR)) {
  550                 struct ifaddr *ifa;
  551                 struct in6_ifaddr *ia6;
  552                 int bad;
  553 
  554                 bad = 1;
  555 #define sa_equal(a1, a2)                                                \
  556         (bcmp((a1), (a2), ((a1))->sin6_len) == 0)
  557                 IF_ADDR_RLOCK(ifp);
  558                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  559                         if (ifa->ifa_addr->sa_family != dst6.sin6_family)
  560                                 continue;
  561                         if (sa_equal(&dst6, ifa->ifa_addr))
  562                                 break;
  563                 }
  564                 KASSERT(ifa != NULL, ("%s: ifa not found for lle %p",
  565                     __func__, lle));
  566 #undef sa_equal
  567 
  568                 ia6 = (struct in6_ifaddr *)ifa;
  569                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  570                         /* Count the packet in the ip address stats */
  571                         ia6->ia_ifa.if_ipackets++;
  572                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  573 
  574                         /*
  575                          * record address information into m_tag.
  576                          */
  577                         (void)ip6_setdstifaddr(m, ia6);
  578 
  579                         bad = 0;
  580                 } else {
  581                         char ip6bufs[INET6_ADDRSTRLEN];
  582                         char ip6bufd[INET6_ADDRSTRLEN];
  583                         /* address is not ready, so discard the packet. */
  584                         nd6log((LOG_INFO,
  585                             "ip6_input: packet to an unready address %s->%s\n",
  586                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  587                             ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
  588                 }
  589                 IF_ADDR_RUNLOCK(ifp);
  590                 LLE_RUNLOCK(lle);
  591                 if (bad)
  592                         goto bad;
  593                 else {
  594                         ours = 1;
  595                         deliverifp = ifp;
  596                         goto hbhcheck;
  597                 }
  598         }
  599         if (lle != NULL)
  600                 LLE_RUNLOCK(lle);
  601 
  602         dst = &rin6.ro_dst;
  603         dst->sin6_len = sizeof(struct sockaddr_in6);
  604         dst->sin6_family = AF_INET6;
  605         dst->sin6_addr = ip6->ip6_dst;
  606         rin6.ro_rt = in6_rtalloc1((struct sockaddr *)dst, 0, 0, M_GETFIB(m));
  607         if (rin6.ro_rt)
  608                 RT_UNLOCK(rin6.ro_rt);
  609 
  610 #define rt6_key(r) ((struct sockaddr_in6 *)((r)->rt_nodes->rn_key))
  611 
  612         /*
  613          * Accept the packet if the forwarding interface to the destination
  614          * according to the routing table is the loopback interface,
  615          * unless the associated route has a gateway.
  616          * Note that this approach causes to accept a packet if there is a
  617          * route to the loopback interface for the destination of the packet.
  618          * But we think it's even useful in some situations, e.g. when using
  619          * a special daemon which wants to intercept the packet.
  620          *
  621          * XXX: some OSes automatically make a cloned route for the destination
  622          * of an outgoing packet.  If the outgoing interface of the packet
  623          * is a loopback one, the kernel would consider the packet to be
  624          * accepted, even if we have no such address assinged on the interface.
  625          * We check the cloned flag of the route entry to reject such cases,
  626          * assuming that route entries for our own addresses are not made by
  627          * cloning (it should be true because in6_addloop explicitly installs
  628          * the host route).  However, we might have to do an explicit check
  629          * while it would be less efficient.  Or, should we rather install a
  630          * reject route for such a case?
  631          */
  632         if (rin6.ro_rt &&
  633             (rin6.ro_rt->rt_flags &
  634              (RTF_HOST|RTF_GATEWAY)) == RTF_HOST &&
  635 #ifdef RTF_WASCLONED
  636             !(rin6.ro_rt->rt_flags & RTF_WASCLONED) &&
  637 #endif
  638 #ifdef RTF_CLONED
  639             !(rin6.ro_rt->rt_flags & RTF_CLONED) &&
  640 #endif
  641 #if 0
  642             /*
  643              * The check below is redundant since the comparison of
  644              * the destination and the key of the rtentry has
  645              * already done through looking up the routing table.
  646              */
  647             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  648             &rt6_key(rin6.ro_rt)->sin6_addr)
  649 #endif
  650             rin6.ro_rt->rt_ifp->if_type == IFT_LOOP) {
  651                 int free_ia6 = 0;
  652                 struct in6_ifaddr *ia6;
  653 
  654                 /*
  655                  * found the loopback route to the interface address
  656                  */
  657                 if (rin6.ro_rt->rt_gateway->sa_family == AF_LINK) {
  658                         struct sockaddr_in6 dest6;
  659 
  660                         bzero(&dest6, sizeof(dest6));
  661                         dest6.sin6_family = AF_INET6;
  662                         dest6.sin6_len = sizeof(dest6);
  663                         dest6.sin6_addr = ip6->ip6_dst;
  664                         ia6 = (struct in6_ifaddr *)
  665                             ifa_ifwithaddr((struct sockaddr *)&dest6);
  666                         if (ia6 == NULL)
  667                                 goto bad;
  668                         free_ia6 = 1;
  669                 }
  670                 else
  671                         ia6 = (struct in6_ifaddr *)rin6.ro_rt->rt_ifa;
  672 
  673                 /*
  674                  * record address information into m_tag.
  675                  */
  676                 (void)ip6_setdstifaddr(m, ia6);
  677 
  678                 /*
  679                  * packets to a tentative, duplicated, or somehow invalid
  680                  * address must not be accepted.
  681                  */
  682                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  683                         /* this address is ready */
  684                         ours = 1;
  685                         deliverifp = ia6->ia_ifp;       /* correct? */
  686                         /* Count the packet in the ip address stats */
  687                         ia6->ia_ifa.if_ipackets++;
  688                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  689                         if (ia6 != NULL && free_ia6 != 0)
  690                                 ifa_free(&ia6->ia_ifa);
  691                         goto hbhcheck;
  692                 } else {
  693                         char ip6bufs[INET6_ADDRSTRLEN];
  694                         char ip6bufd[INET6_ADDRSTRLEN];
  695                         /* address is not ready, so discard the packet. */
  696                         nd6log((LOG_INFO,
  697                             "ip6_input: packet to an unready address %s->%s\n",
  698                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  699                             ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
  700 
  701                         if (ia6 != NULL && free_ia6 != 0)
  702                                 ifa_free(&ia6->ia_ifa);
  703                         goto bad;
  704                 }
  705         }
  706 
  707         /*
  708          * FAITH (Firewall Aided Internet Translator)
  709          */
  710         if (V_ip6_keepfaith) {
  711                 if (rin6.ro_rt && rin6.ro_rt->rt_ifp &&
  712                     rin6.ro_rt->rt_ifp->if_type == IFT_FAITH) {
  713                         /* XXX do we need more sanity checks? */
  714                         ours = 1;
  715                         deliverifp = rin6.ro_rt->rt_ifp; /* faith */
  716                         goto hbhcheck;
  717                 }
  718         }
  719 
  720         /*
  721          * Now there is no reason to process the packet if it's not our own
  722          * and we're not a router.
  723          */
  724         if (!V_ip6_forwarding) {
  725                 V_ip6stat.ip6s_cantforward++;
  726                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  727                 goto bad;
  728         }
  729 
  730   hbhcheck:
  731         /*
  732          * record address information into m_tag, if we don't have one yet.
  733          * note that we are unable to record it, if the address is not listed
  734          * as our interface address (e.g. multicast addresses, addresses
  735          * within FAITH prefixes and such).
  736          */
  737         if (deliverifp) {
  738                 struct in6_ifaddr *ia6;
  739 
  740                 if ((ia6 = ip6_getdstifaddr(m)) != NULL) {
  741                         ifa_free(&ia6->ia_ifa);
  742                 } else {
  743                         ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
  744                         if (ia6) {
  745                                 if (!ip6_setdstifaddr(m, ia6)) {
  746                                         /*
  747                                          * XXX maybe we should drop the packet here,
  748                                          * as we could not provide enough information
  749                                          * to the upper layers.
  750                                          */
  751                                 }
  752                                 ifa_free(&ia6->ia_ifa);
  753                         }
  754                 }
  755         }
  756 
  757         /*
  758          * Process Hop-by-Hop options header if it's contained.
  759          * m may be modified in ip6_hopopts_input().
  760          * If a JumboPayload option is included, plen will also be modified.
  761          */
  762         plen = (u_int32_t)ntohs(ip6->ip6_plen);
  763         if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
  764                 struct ip6_hbh *hbh;
  765 
  766                 if (ip6_hopopts_input(&plen, &rtalert, &m, &off)) {
  767 #if 0   /*touches NULL pointer*/
  768                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  769 #endif
  770                         goto out;       /* m have already been freed */
  771                 }
  772 
  773                 /* adjust pointer */
  774                 ip6 = mtod(m, struct ip6_hdr *);
  775 
  776                 /*
  777                  * if the payload length field is 0 and the next header field
  778                  * indicates Hop-by-Hop Options header, then a Jumbo Payload
  779                  * option MUST be included.
  780                  */
  781                 if (ip6->ip6_plen == 0 && plen == 0) {
  782                         /*
  783                          * Note that if a valid jumbo payload option is
  784                          * contained, ip6_hopopts_input() must set a valid
  785                          * (non-zero) payload length to the variable plen.
  786                          */
  787                         V_ip6stat.ip6s_badoptions++;
  788                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  789                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  790                         icmp6_error(m, ICMP6_PARAM_PROB,
  791                                     ICMP6_PARAMPROB_HEADER,
  792                                     (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
  793                         goto out;
  794                 }
  795 #ifndef PULLDOWN_TEST
  796                 /* ip6_hopopts_input() ensures that mbuf is contiguous */
  797                 hbh = (struct ip6_hbh *)(ip6 + 1);
  798 #else
  799                 IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  800                         sizeof(struct ip6_hbh));
  801                 if (hbh == NULL) {
  802                         V_ip6stat.ip6s_tooshort++;
  803                         goto out;
  804                 }
  805 #endif
  806                 nxt = hbh->ip6h_nxt;
  807 
  808                 /*
  809                  * If we are acting as a router and the packet contains a
  810                  * router alert option, see if we know the option value.
  811                  * Currently, we only support the option value for MLD, in which
  812                  * case we should pass the packet to the multicast routing
  813                  * daemon.
  814                  */
  815                 if (rtalert != ~0) {
  816                         switch (rtalert) {
  817                         case IP6OPT_RTALERT_MLD:
  818                                 if (V_ip6_forwarding)
  819                                         ours = 1;
  820                                 break;
  821                         default:
  822                                 /*
  823                                  * RFC2711 requires unrecognized values must be
  824                                  * silently ignored.
  825                                  */
  826                                 break;
  827                         }
  828                 }
  829         } else
  830                 nxt = ip6->ip6_nxt;
  831 
  832         /*
  833          * Check that the amount of data in the buffers
  834          * is as at least much as the IPv6 header would have us expect.
  835          * Trim mbufs if longer than we expect.
  836          * Drop packet if shorter than we expect.
  837          */
  838         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
  839                 V_ip6stat.ip6s_tooshort++;
  840                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  841                 goto bad;
  842         }
  843         if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
  844                 if (m->m_len == m->m_pkthdr.len) {
  845                         m->m_len = sizeof(struct ip6_hdr) + plen;
  846                         m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
  847                 } else
  848                         m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
  849         }
  850 
  851         /*
  852          * Forward if desirable.
  853          */
  854         if (V_ip6_mrouter &&
  855             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  856                 /*
  857                  * If we are acting as a multicast router, all
  858                  * incoming multicast packets are passed to the
  859                  * kernel-level multicast forwarding function.
  860                  * The packet is returned (relatively) intact; if
  861                  * ip6_mforward() returns a non-zero value, the packet
  862                  * must be discarded, else it may be accepted below.
  863                  *
  864                  * XXX TODO: Check hlim and multicast scope here to avoid
  865                  * unnecessarily calling into ip6_mforward().
  866                  */
  867                 if (ip6_mforward &&
  868                     ip6_mforward(ip6, m->m_pkthdr.rcvif, m)) {
  869                         IP6STAT_INC(ip6s_cantforward);
  870                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  871                         goto bad;
  872                 }
  873         } else if (!ours) {
  874                 ip6_forward(m, srcrt);
  875                 goto out;
  876         }
  877 
  878         ip6 = mtod(m, struct ip6_hdr *);
  879 
  880         /*
  881          * Malicious party may be able to use IPv4 mapped addr to confuse
  882          * tcp/udp stack and bypass security checks (act as if it was from
  883          * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
  884          *
  885          * For SIIT end node behavior, you may want to disable the check.
  886          * However, you will  become vulnerable to attacks using IPv4 mapped
  887          * source.
  888          */
  889         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  890             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  891                 V_ip6stat.ip6s_badscope++;
  892                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  893                 goto bad;
  894         }
  895 
  896         /*
  897          * Tell launch routine the next header
  898          */
  899         V_ip6stat.ip6s_delivered++;
  900         in6_ifstat_inc(deliverifp, ifs6_in_deliver);
  901         nest = 0;
  902 
  903         while (nxt != IPPROTO_DONE) {
  904                 if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
  905                         V_ip6stat.ip6s_toomanyhdr++;
  906                         goto bad;
  907                 }
  908 
  909                 /*
  910                  * protection against faulty packet - there should be
  911                  * more sanity checks in header chain processing.
  912                  */
  913                 if (m->m_pkthdr.len < off) {
  914                         V_ip6stat.ip6s_tooshort++;
  915                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  916                         goto bad;
  917                 }
  918 
  919 #ifdef IPSEC
  920                 /*
  921                  * enforce IPsec policy checking if we are seeing last header.
  922                  * note that we do not visit this with protocols with pcb layer
  923                  * code - like udp/tcp/raw ip.
  924                  */
  925                 if (ip6_ipsec_input(m, nxt))
  926                         goto bad;
  927 #endif /* IPSEC */
  928 
  929                 /*
  930                  * Use mbuf flags to propagate Router Alert option to
  931                  * ICMPv6 layer, as hop-by-hop options have been stripped.
  932                  */
  933                 if (nxt == IPPROTO_ICMPV6 && rtalert != ~0)
  934                         m->m_flags |= M_RTALERT_MLD;
  935 
  936                 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
  937         }
  938         goto out;
  939 bad:
  940         m_freem(m);
  941 out:
  942         if (rin6.ro_rt)
  943                 RTFREE(rin6.ro_rt);
  944 }
  945 
  946 /*
  947  * set/grab in6_ifaddr correspond to IPv6 destination address.
  948  * XXX backward compatibility wrapper
  949  *
  950  * XXXRW: We should bump the refcount on ia6 before sticking it in the m_tag,
  951  * and then bump it when the tag is copied, and release it when the tag is
  952  * freed.  Unfortunately, m_tags don't support deep copies (yet), so instead
  953  * we just bump the ia refcount when we receive it.  This should be fixed.
  954  */
  955 static struct ip6aux *
  956 ip6_setdstifaddr(struct mbuf *m, struct in6_ifaddr *ia6)
  957 {
  958         struct ip6aux *ip6a;
  959 
  960         ip6a = ip6_addaux(m);
  961         if (ip6a)
  962                 ip6a->ip6a_dstia6 = ia6;
  963         return ip6a;    /* NULL if failed to set */
  964 }
  965 
  966 struct in6_ifaddr *
  967 ip6_getdstifaddr(struct mbuf *m)
  968 {
  969         struct ip6aux *ip6a;
  970         struct in6_ifaddr *ia;
  971 
  972         ip6a = ip6_findaux(m);
  973         if (ip6a) {
  974                 ia = ip6a->ip6a_dstia6;
  975                 ifa_ref(&ia->ia_ifa);
  976                 return ia;
  977         } else
  978                 return NULL;
  979 }
  980 
  981 /*
  982  * Hop-by-Hop options header processing. If a valid jumbo payload option is
  983  * included, the real payload length will be stored in plenp.
  984  *
  985  * rtalertp - XXX: should be stored more smart way
  986  */
  987 static int
  988 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
  989     struct mbuf **mp, int *offp)
  990 {
  991         struct mbuf *m = *mp;
  992         int off = *offp, hbhlen;
  993         struct ip6_hbh *hbh;
  994 
  995         /* validation of the length of the header */
  996 #ifndef PULLDOWN_TEST
  997         IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
  998         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
  999         hbhlen = (hbh->ip6h_len + 1) << 3;
 1000 
 1001         IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
 1002         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
 1003 #else
 1004         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
 1005                 sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
 1006         if (hbh == NULL) {
 1007                 V_ip6stat.ip6s_tooshort++;
 1008                 return -1;
 1009         }
 1010         hbhlen = (hbh->ip6h_len + 1) << 3;
 1011         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
 1012                 hbhlen);
 1013         if (hbh == NULL) {
 1014                 V_ip6stat.ip6s_tooshort++;
 1015                 return -1;
 1016         }
 1017 #endif
 1018         off += hbhlen;
 1019         hbhlen -= sizeof(struct ip6_hbh);
 1020         if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
 1021                                 hbhlen, rtalertp, plenp) < 0)
 1022                 return (-1);
 1023 
 1024         *offp = off;
 1025         *mp = m;
 1026         return (0);
 1027 }
 1028 
 1029 /*
 1030  * Search header for all Hop-by-hop options and process each option.
 1031  * This function is separate from ip6_hopopts_input() in order to
 1032  * handle a case where the sending node itself process its hop-by-hop
 1033  * options header. In such a case, the function is called from ip6_output().
 1034  *
 1035  * The function assumes that hbh header is located right after the IPv6 header
 1036  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
 1037  * opthead + hbhlen is located in continuous memory region.
 1038  */
 1039 int
 1040 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
 1041     u_int32_t *rtalertp, u_int32_t *plenp)
 1042 {
 1043         struct ip6_hdr *ip6;
 1044         int optlen = 0;
 1045         u_int8_t *opt = opthead;
 1046         u_int16_t rtalert_val;
 1047         u_int32_t jumboplen;
 1048         const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
 1049 
 1050         for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
 1051                 switch (*opt) {
 1052                 case IP6OPT_PAD1:
 1053                         optlen = 1;
 1054                         break;
 1055                 case IP6OPT_PADN:
 1056                         if (hbhlen < IP6OPT_MINLEN) {
 1057                                 V_ip6stat.ip6s_toosmall++;
 1058                                 goto bad;
 1059                         }
 1060                         optlen = *(opt + 1) + 2;
 1061                         break;
 1062                 case IP6OPT_ROUTER_ALERT:
 1063                         /* XXX may need check for alignment */
 1064                         if (hbhlen < IP6OPT_RTALERT_LEN) {
 1065                                 V_ip6stat.ip6s_toosmall++;
 1066                                 goto bad;
 1067                         }
 1068                         if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
 1069                                 /* XXX stat */
 1070                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1071                                     ICMP6_PARAMPROB_HEADER,
 1072                                     erroff + opt + 1 - opthead);
 1073                                 return (-1);
 1074                         }
 1075                         optlen = IP6OPT_RTALERT_LEN;
 1076                         bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
 1077                         *rtalertp = ntohs(rtalert_val);
 1078                         break;
 1079                 case IP6OPT_JUMBO:
 1080                         /* XXX may need check for alignment */
 1081                         if (hbhlen < IP6OPT_JUMBO_LEN) {
 1082                                 V_ip6stat.ip6s_toosmall++;
 1083                                 goto bad;
 1084                         }
 1085                         if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
 1086                                 /* XXX stat */
 1087                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1088                                     ICMP6_PARAMPROB_HEADER,
 1089                                     erroff + opt + 1 - opthead);
 1090                                 return (-1);
 1091                         }
 1092                         optlen = IP6OPT_JUMBO_LEN;
 1093 
 1094                         /*
 1095                          * IPv6 packets that have non 0 payload length
 1096                          * must not contain a jumbo payload option.
 1097                          */
 1098                         ip6 = mtod(m, struct ip6_hdr *);
 1099                         if (ip6->ip6_plen) {
 1100                                 V_ip6stat.ip6s_badoptions++;
 1101                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1102                                     ICMP6_PARAMPROB_HEADER,
 1103                                     erroff + opt - opthead);
 1104                                 return (-1);
 1105                         }
 1106 
 1107                         /*
 1108                          * We may see jumbolen in unaligned location, so
 1109                          * we'd need to perform bcopy().
 1110                          */
 1111                         bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
 1112                         jumboplen = (u_int32_t)htonl(jumboplen);
 1113 
 1114 #if 1
 1115                         /*
 1116                          * if there are multiple jumbo payload options,
 1117                          * *plenp will be non-zero and the packet will be
 1118                          * rejected.
 1119                          * the behavior may need some debate in ipngwg -
 1120                          * multiple options does not make sense, however,
 1121                          * there's no explicit mention in specification.
 1122                          */
 1123                         if (*plenp != 0) {
 1124                                 V_ip6stat.ip6s_badoptions++;
 1125                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1126                                     ICMP6_PARAMPROB_HEADER,
 1127                                     erroff + opt + 2 - opthead);
 1128                                 return (-1);
 1129                         }
 1130 #endif
 1131 
 1132                         /*
 1133                          * jumbo payload length must be larger than 65535.
 1134                          */
 1135                         if (jumboplen <= IPV6_MAXPACKET) {
 1136                                 V_ip6stat.ip6s_badoptions++;
 1137                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1138                                     ICMP6_PARAMPROB_HEADER,
 1139                                     erroff + opt + 2 - opthead);
 1140                                 return (-1);
 1141                         }
 1142                         *plenp = jumboplen;
 1143 
 1144                         break;
 1145                 default:                /* unknown option */
 1146                         if (hbhlen < IP6OPT_MINLEN) {
 1147                                 V_ip6stat.ip6s_toosmall++;
 1148                                 goto bad;
 1149                         }
 1150                         optlen = ip6_unknown_opt(opt, m,
 1151                             erroff + opt - opthead);
 1152                         if (optlen == -1)
 1153                                 return (-1);
 1154                         optlen += 2;
 1155                         break;
 1156                 }
 1157         }
 1158 
 1159         return (0);
 1160 
 1161   bad:
 1162         m_freem(m);
 1163         return (-1);
 1164 }
 1165 
 1166 /*
 1167  * Unknown option processing.
 1168  * The third argument `off' is the offset from the IPv6 header to the option,
 1169  * which is necessary if the IPv6 header the and option header and IPv6 header
 1170  * is not continuous in order to return an ICMPv6 error.
 1171  */
 1172 int
 1173 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
 1174 {
 1175         struct ip6_hdr *ip6;
 1176 
 1177         switch (IP6OPT_TYPE(*optp)) {
 1178         case IP6OPT_TYPE_SKIP: /* ignore the option */
 1179                 return ((int)*(optp + 1));
 1180         case IP6OPT_TYPE_DISCARD:       /* silently discard */
 1181                 m_freem(m);
 1182                 return (-1);
 1183         case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
 1184                 V_ip6stat.ip6s_badoptions++;
 1185                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
 1186                 return (-1);
 1187         case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
 1188                 V_ip6stat.ip6s_badoptions++;
 1189                 ip6 = mtod(m, struct ip6_hdr *);
 1190                 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
 1191                     (m->m_flags & (M_BCAST|M_MCAST)))
 1192                         m_freem(m);
 1193                 else
 1194                         icmp6_error(m, ICMP6_PARAM_PROB,
 1195                                     ICMP6_PARAMPROB_OPTION, off);
 1196                 return (-1);
 1197         }
 1198 
 1199         m_freem(m);             /* XXX: NOTREACHED */
 1200         return (-1);
 1201 }
 1202 
 1203 /*
 1204  * Create the "control" list for this pcb.
 1205  * These functions will not modify mbuf chain at all.
 1206  *
 1207  * With KAME mbuf chain restriction:
 1208  * The routine will be called from upper layer handlers like tcp6_input().
 1209  * Thus the routine assumes that the caller (tcp6_input) have already
 1210  * called IP6_EXTHDR_CHECK() and all the extension headers are located in the
 1211  * very first mbuf on the mbuf chain.
 1212  *
 1213  * ip6_savecontrol_v4 will handle those options that are possible to be
 1214  * set on a v4-mapped socket.
 1215  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
 1216  * options and handle the v6-only ones itself.
 1217  */
 1218 struct mbuf **
 1219 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
 1220     int *v4only)
 1221 {
 1222         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1223 
 1224 #ifdef SO_TIMESTAMP
 1225         if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
 1226                 struct timeval tv;
 1227 
 1228                 microtime(&tv);
 1229                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
 1230                     SCM_TIMESTAMP, SOL_SOCKET);
 1231                 if (*mp)
 1232                         mp = &(*mp)->m_next;
 1233         }
 1234 #endif
 1235 
 1236 #define IS2292(inp, x, y)       (((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
 1237         /* RFC 2292 sec. 5 */
 1238         if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
 1239                 struct in6_pktinfo pi6;
 1240 
 1241                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1242 #ifdef INET
 1243                         struct ip *ip;
 1244 
 1245                         ip = mtod(m, struct ip *);
 1246                         pi6.ipi6_addr.s6_addr32[0] = 0;
 1247                         pi6.ipi6_addr.s6_addr32[1] = 0;
 1248                         pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
 1249                         pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
 1250 #else
 1251                         /* We won't hit this code */
 1252                         bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
 1253 #endif
 1254                 } else {        
 1255                         bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
 1256                         in6_clearscope(&pi6.ipi6_addr); /* XXX */
 1257                 }
 1258                 pi6.ipi6_ifindex =
 1259                     (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
 1260 
 1261                 *mp = sbcreatecontrol((caddr_t) &pi6,
 1262                     sizeof(struct in6_pktinfo),
 1263                     IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6);
 1264                 if (*mp)
 1265                         mp = &(*mp)->m_next;
 1266         }
 1267 
 1268         if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
 1269                 int hlim;
 1270 
 1271                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1272 #ifdef INET
 1273                         struct ip *ip;
 1274 
 1275                         ip = mtod(m, struct ip *);
 1276                         hlim = ip->ip_ttl;
 1277 #else
 1278                         /* We won't hit this code */
 1279                         hlim = 0;
 1280 #endif
 1281                 } else {
 1282                         hlim = ip6->ip6_hlim & 0xff;
 1283                 }
 1284                 *mp = sbcreatecontrol((caddr_t) &hlim, sizeof(int),
 1285                     IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
 1286                     IPPROTO_IPV6);
 1287                 if (*mp)
 1288                         mp = &(*mp)->m_next;
 1289         }
 1290 
 1291         if ((inp->inp_flags & IN6P_TCLASS) != 0) {
 1292                 int tclass;
 1293 
 1294                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1295 #ifdef INET
 1296                         struct ip *ip;
 1297 
 1298                         ip = mtod(m, struct ip *);
 1299                         tclass = ip->ip_tos;
 1300 #else
 1301                         /* We won't hit this code */
 1302                         tclass = 0;
 1303 #endif
 1304                 } else {
 1305                         u_int32_t flowinfo;
 1306 
 1307                         flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
 1308                         flowinfo >>= 20;
 1309                         tclass = flowinfo & 0xff;
 1310                 }
 1311                 *mp = sbcreatecontrol((caddr_t) &tclass, sizeof(int),
 1312                     IPV6_TCLASS, IPPROTO_IPV6);
 1313                 if (*mp)
 1314                         mp = &(*mp)->m_next;
 1315         }
 1316 
 1317         if (v4only != NULL) {
 1318                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1319                         *v4only = 1;
 1320                 } else {
 1321                         *v4only = 0;
 1322                 }
 1323         }
 1324 
 1325         return (mp);
 1326 }
 1327 
 1328 void
 1329 ip6_savecontrol(struct inpcb *in6p, struct mbuf *m, struct mbuf **mp)
 1330 {
 1331         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1332         int v4only = 0;
 1333 
 1334         mp = ip6_savecontrol_v4(in6p, m, mp, &v4only);
 1335         if (v4only)
 1336                 return;
 1337 
 1338         /*
 1339          * IPV6_HOPOPTS socket option.  Recall that we required super-user
 1340          * privilege for the option (see ip6_ctloutput), but it might be too
 1341          * strict, since there might be some hop-by-hop options which can be
 1342          * returned to normal user.
 1343          * See also RFC 2292 section 6 (or RFC 3542 section 8).
 1344          */
 1345         if ((in6p->inp_flags & IN6P_HOPOPTS) != 0) {
 1346                 /*
 1347                  * Check if a hop-by-hop options header is contatined in the
 1348                  * received packet, and if so, store the options as ancillary
 1349                  * data. Note that a hop-by-hop options header must be
 1350                  * just after the IPv6 header, which is assured through the
 1351                  * IPv6 input processing.
 1352                  */
 1353                 if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
 1354                         struct ip6_hbh *hbh;
 1355                         int hbhlen = 0;
 1356 #ifdef PULLDOWN_TEST
 1357                         struct mbuf *ext;
 1358 #endif
 1359 
 1360 #ifndef PULLDOWN_TEST
 1361                         hbh = (struct ip6_hbh *)(ip6 + 1);
 1362                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1363 #else
 1364                         ext = ip6_pullexthdr(m, sizeof(struct ip6_hdr),
 1365                             ip6->ip6_nxt);
 1366                         if (ext == NULL) {
 1367                                 V_ip6stat.ip6s_tooshort++;
 1368                                 return;
 1369                         }
 1370                         hbh = mtod(ext, struct ip6_hbh *);
 1371                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1372                         if (hbhlen != ext->m_len) {
 1373                                 m_freem(ext);
 1374                                 V_ip6stat.ip6s_tooshort++;
 1375                                 return;
 1376                         }
 1377 #endif
 1378 
 1379                         /*
 1380                          * XXX: We copy the whole header even if a
 1381                          * jumbo payload option is included, the option which
 1382                          * is to be removed before returning according to
 1383                          * RFC2292.
 1384                          * Note: this constraint is removed in RFC3542
 1385                          */
 1386                         *mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
 1387                             IS2292(in6p, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
 1388                             IPPROTO_IPV6);
 1389                         if (*mp)
 1390                                 mp = &(*mp)->m_next;
 1391 #ifdef PULLDOWN_TEST
 1392                         m_freem(ext);
 1393 #endif
 1394                 }
 1395         }
 1396 
 1397         if ((in6p->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
 1398                 int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
 1399 
 1400                 /*
 1401                  * Search for destination options headers or routing
 1402                  * header(s) through the header chain, and stores each
 1403                  * header as ancillary data.
 1404                  * Note that the order of the headers remains in
 1405                  * the chain of ancillary data.
 1406                  */
 1407                 while (1) {     /* is explicit loop prevention necessary? */
 1408                         struct ip6_ext *ip6e = NULL;
 1409                         int elen;
 1410 #ifdef PULLDOWN_TEST
 1411                         struct mbuf *ext = NULL;
 1412 #endif
 1413 
 1414                         /*
 1415                          * if it is not an extension header, don't try to
 1416                          * pull it from the chain.
 1417                          */
 1418                         switch (nxt) {
 1419                         case IPPROTO_DSTOPTS:
 1420                         case IPPROTO_ROUTING:
 1421                         case IPPROTO_HOPOPTS:
 1422                         case IPPROTO_AH: /* is it possible? */
 1423                                 break;
 1424                         default:
 1425                                 goto loopend;
 1426                         }
 1427 
 1428 #ifndef PULLDOWN_TEST
 1429                         if (off + sizeof(*ip6e) > m->m_len)
 1430                                 goto loopend;
 1431                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
 1432                         if (nxt == IPPROTO_AH)
 1433                                 elen = (ip6e->ip6e_len + 2) << 2;
 1434                         else
 1435                                 elen = (ip6e->ip6e_len + 1) << 3;
 1436                         if (off + elen > m->m_len)
 1437                                 goto loopend;
 1438 #else
 1439                         ext = ip6_pullexthdr(m, off, nxt);
 1440                         if (ext == NULL) {
 1441                                 V_ip6stat.ip6s_tooshort++;
 1442                                 return;
 1443                         }
 1444                         ip6e = mtod(ext, struct ip6_ext *);
 1445                         if (nxt == IPPROTO_AH)
 1446                                 elen = (ip6e->ip6e_len + 2) << 2;
 1447                         else
 1448                                 elen = (ip6e->ip6e_len + 1) << 3;
 1449                         if (elen != ext->m_len) {
 1450                                 m_freem(ext);
 1451                                 V_ip6stat.ip6s_tooshort++;
 1452                                 return;
 1453                         }
 1454 #endif
 1455 
 1456                         switch (nxt) {
 1457                         case IPPROTO_DSTOPTS:
 1458                                 if (!(in6p->inp_flags & IN6P_DSTOPTS))
 1459                                         break;
 1460 
 1461                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1462                                     IS2292(in6p,
 1463                                         IPV6_2292DSTOPTS, IPV6_DSTOPTS),
 1464                                     IPPROTO_IPV6);
 1465                                 if (*mp)
 1466                                         mp = &(*mp)->m_next;
 1467                                 break;
 1468                         case IPPROTO_ROUTING:
 1469                                 if (!in6p->inp_flags & IN6P_RTHDR)
 1470                                         break;
 1471 
 1472                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1473                                     IS2292(in6p, IPV6_2292RTHDR, IPV6_RTHDR),
 1474                                     IPPROTO_IPV6);
 1475                                 if (*mp)
 1476                                         mp = &(*mp)->m_next;
 1477                                 break;
 1478                         case IPPROTO_HOPOPTS:
 1479                         case IPPROTO_AH: /* is it possible? */
 1480                                 break;
 1481 
 1482                         default:
 1483                                 /*
 1484                                  * other cases have been filtered in the above.
 1485                                  * none will visit this case.  here we supply
 1486                                  * the code just in case (nxt overwritten or
 1487                                  * other cases).
 1488                                  */
 1489 #ifdef PULLDOWN_TEST
 1490                                 m_freem(ext);
 1491 #endif
 1492                                 goto loopend;
 1493 
 1494                         }
 1495 
 1496                         /* proceed with the next header. */
 1497                         off += elen;
 1498                         nxt = ip6e->ip6e_nxt;
 1499                         ip6e = NULL;
 1500 #ifdef PULLDOWN_TEST
 1501                         m_freem(ext);
 1502                         ext = NULL;
 1503 #endif
 1504                 }
 1505           loopend:
 1506                 ;
 1507         }
 1508 }
 1509 #undef IS2292
 1510 
 1511 void
 1512 ip6_notify_pmtu(struct inpcb *in6p, struct sockaddr_in6 *dst, u_int32_t *mtu)
 1513 {
 1514         struct socket *so;
 1515         struct mbuf *m_mtu;
 1516         struct ip6_mtuinfo mtuctl;
 1517 
 1518         so =  in6p->inp_socket;
 1519 
 1520         if (mtu == NULL)
 1521                 return;
 1522 
 1523 #ifdef DIAGNOSTIC
 1524         if (so == NULL)         /* I believe this is impossible */
 1525                 panic("ip6_notify_pmtu: socket is NULL");
 1526 #endif
 1527 
 1528         bzero(&mtuctl, sizeof(mtuctl)); /* zero-clear for safety */
 1529         mtuctl.ip6m_mtu = *mtu;
 1530         mtuctl.ip6m_addr = *dst;
 1531         if (sa6_recoverscope(&mtuctl.ip6m_addr))
 1532                 return;
 1533 
 1534         if ((m_mtu = sbcreatecontrol((caddr_t)&mtuctl, sizeof(mtuctl),
 1535             IPV6_PATHMTU, IPPROTO_IPV6)) == NULL)
 1536                 return;
 1537 
 1538         if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
 1539             == 0) {
 1540                 m_freem(m_mtu);
 1541                 /* XXX: should count statistics */
 1542         } else
 1543                 sorwakeup(so);
 1544 
 1545         return;
 1546 }
 1547 
 1548 #ifdef PULLDOWN_TEST
 1549 /*
 1550  * pull single extension header from mbuf chain.  returns single mbuf that
 1551  * contains the result, or NULL on error.
 1552  */
 1553 static struct mbuf *
 1554 ip6_pullexthdr(struct mbuf *m, size_t off, int nxt)
 1555 {
 1556         struct ip6_ext ip6e;
 1557         size_t elen;
 1558         struct mbuf *n;
 1559 
 1560 #ifdef DIAGNOSTIC
 1561         switch (nxt) {
 1562         case IPPROTO_DSTOPTS:
 1563         case IPPROTO_ROUTING:
 1564         case IPPROTO_HOPOPTS:
 1565         case IPPROTO_AH: /* is it possible? */
 1566                 break;
 1567         default:
 1568                 printf("ip6_pullexthdr: invalid nxt=%d\n", nxt);
 1569         }
 1570 #endif
 1571 
 1572         m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1573         if (nxt == IPPROTO_AH)
 1574                 elen = (ip6e.ip6e_len + 2) << 2;
 1575         else
 1576                 elen = (ip6e.ip6e_len + 1) << 3;
 1577 
 1578         MGET(n, M_DONTWAIT, MT_DATA);
 1579         if (n && elen >= MLEN) {
 1580                 MCLGET(n, M_DONTWAIT);
 1581                 if ((n->m_flags & M_EXT) == 0) {
 1582                         m_free(n);
 1583                         n = NULL;
 1584                 }
 1585         }
 1586         if (!n)
 1587                 return NULL;
 1588 
 1589         n->m_len = 0;
 1590         if (elen >= M_TRAILINGSPACE(n)) {
 1591                 m_free(n);
 1592                 return NULL;
 1593         }
 1594 
 1595         m_copydata(m, off, elen, mtod(n, caddr_t));
 1596         n->m_len = elen;
 1597         return n;
 1598 }
 1599 #endif
 1600 
 1601 /*
 1602  * Get pointer to the previous header followed by the header
 1603  * currently processed.
 1604  * XXX: This function supposes that
 1605  *      M includes all headers,
 1606  *      the next header field and the header length field of each header
 1607  *      are valid, and
 1608  *      the sum of each header length equals to OFF.
 1609  * Because of these assumptions, this function must be called very
 1610  * carefully. Moreover, it will not be used in the near future when
 1611  * we develop `neater' mechanism to process extension headers.
 1612  */
 1613 char *
 1614 ip6_get_prevhdr(struct mbuf *m, int off)
 1615 {
 1616         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1617 
 1618         if (off == sizeof(struct ip6_hdr))
 1619                 return (&ip6->ip6_nxt);
 1620         else {
 1621                 int len, nxt;
 1622                 struct ip6_ext *ip6e = NULL;
 1623 
 1624                 nxt = ip6->ip6_nxt;
 1625                 len = sizeof(struct ip6_hdr);
 1626                 while (len < off) {
 1627                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + len);
 1628 
 1629                         switch (nxt) {
 1630                         case IPPROTO_FRAGMENT:
 1631                                 len += sizeof(struct ip6_frag);
 1632                                 break;
 1633                         case IPPROTO_AH:
 1634                                 len += (ip6e->ip6e_len + 2) << 2;
 1635                                 break;
 1636                         default:
 1637                                 len += (ip6e->ip6e_len + 1) << 3;
 1638                                 break;
 1639                         }
 1640                         nxt = ip6e->ip6e_nxt;
 1641                 }
 1642                 if (ip6e)
 1643                         return (&ip6e->ip6e_nxt);
 1644                 else
 1645                         return NULL;
 1646         }
 1647 }
 1648 
 1649 /*
 1650  * get next header offset.  m will be retained.
 1651  */
 1652 int
 1653 ip6_nexthdr(struct mbuf *m, int off, int proto, int *nxtp)
 1654 {
 1655         struct ip6_hdr ip6;
 1656         struct ip6_ext ip6e;
 1657         struct ip6_frag fh;
 1658 
 1659         /* just in case */
 1660         if (m == NULL)
 1661                 panic("ip6_nexthdr: m == NULL");
 1662         if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
 1663                 return -1;
 1664 
 1665         switch (proto) {
 1666         case IPPROTO_IPV6:
 1667                 if (m->m_pkthdr.len < off + sizeof(ip6))
 1668                         return -1;
 1669                 m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
 1670                 if (nxtp)
 1671                         *nxtp = ip6.ip6_nxt;
 1672                 off += sizeof(ip6);
 1673                 return off;
 1674 
 1675         case IPPROTO_FRAGMENT:
 1676                 /*
 1677                  * terminate parsing if it is not the first fragment,
 1678                  * it does not make sense to parse through it.
 1679                  */
 1680                 if (m->m_pkthdr.len < off + sizeof(fh))
 1681                         return -1;
 1682                 m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
 1683                 /* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
 1684                 if (fh.ip6f_offlg & IP6F_OFF_MASK)
 1685                         return -1;
 1686                 if (nxtp)
 1687                         *nxtp = fh.ip6f_nxt;
 1688                 off += sizeof(struct ip6_frag);
 1689                 return off;
 1690 
 1691         case IPPROTO_AH:
 1692                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1693                         return -1;
 1694                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1695                 if (nxtp)
 1696                         *nxtp = ip6e.ip6e_nxt;
 1697                 off += (ip6e.ip6e_len + 2) << 2;
 1698                 return off;
 1699 
 1700         case IPPROTO_HOPOPTS:
 1701         case IPPROTO_ROUTING:
 1702         case IPPROTO_DSTOPTS:
 1703                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1704                         return -1;
 1705                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1706                 if (nxtp)
 1707                         *nxtp = ip6e.ip6e_nxt;
 1708                 off += (ip6e.ip6e_len + 1) << 3;
 1709                 return off;
 1710 
 1711         case IPPROTO_NONE:
 1712         case IPPROTO_ESP:
 1713         case IPPROTO_IPCOMP:
 1714                 /* give up */
 1715                 return -1;
 1716 
 1717         default:
 1718                 return -1;
 1719         }
 1720 
 1721         return -1;
 1722 }
 1723 
 1724 /*
 1725  * get offset for the last header in the chain.  m will be kept untainted.
 1726  */
 1727 int
 1728 ip6_lasthdr(struct mbuf *m, int off, int proto, int *nxtp)
 1729 {
 1730         int newoff;
 1731         int nxt;
 1732 
 1733         if (!nxtp) {
 1734                 nxt = -1;
 1735                 nxtp = &nxt;
 1736         }
 1737         while (1) {
 1738                 newoff = ip6_nexthdr(m, off, proto, nxtp);
 1739                 if (newoff < 0)
 1740                         return off;
 1741                 else if (newoff < off)
 1742                         return -1;      /* invalid */
 1743                 else if (newoff == off)
 1744                         return newoff;
 1745 
 1746                 off = newoff;
 1747                 proto = *nxtp;
 1748         }
 1749 }
 1750 
 1751 struct ip6aux *
 1752 ip6_addaux(struct mbuf *m)
 1753 {
 1754         struct m_tag *mtag;
 1755 
 1756         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1757         if (!mtag) {
 1758                 mtag = m_tag_get(PACKET_TAG_IPV6_INPUT, sizeof(struct ip6aux),
 1759                     M_NOWAIT);
 1760                 if (mtag) {
 1761                         m_tag_prepend(m, mtag);
 1762                         bzero(mtag + 1, sizeof(struct ip6aux));
 1763                 }
 1764         }
 1765         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1766 }
 1767 
 1768 struct ip6aux *
 1769 ip6_findaux(struct mbuf *m)
 1770 {
 1771         struct m_tag *mtag;
 1772 
 1773         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1774         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1775 }
 1776 
 1777 void
 1778 ip6_delaux(struct mbuf *m)
 1779 {
 1780         struct m_tag *mtag;
 1781 
 1782         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1783         if (mtag)
 1784                 m_tag_delete(m, mtag);
 1785 }
 1786 
 1787 /*
 1788  * System control for IP6
 1789  */
 1790 
 1791 u_char  inet6ctlerrmap[PRC_NCMDS] = {
 1792         0,              0,              0,              0,
 1793         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1794         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1795         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1796         0,              0,              0,              0,
 1797         ENOPROTOOPT
 1798 };

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