453 lines
13 KiB
C
453 lines
13 KiB
C
/* $NetBSD: ip6_forward.c,v 1.73 2014/05/30 01:39:03 christos Exp $ */
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/* $KAME: ip6_forward.c,v 1.109 2002/09/11 08:10:17 sakane Exp $ */
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/*
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: ip6_forward.c,v 1.73 2014/05/30 01:39:03 christos Exp $");
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#include "opt_gateway.h"
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#include "opt_ipsec.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/domain.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/errno.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/syslog.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/pfil.h>
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#include <netinet/in.h>
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#include <netinet/in_var.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/ip6_private.h>
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#include <netinet6/scope6_var.h>
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#include <netinet/icmp6.h>
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#include <netinet6/nd6.h>
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#ifdef IPSEC
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#include <netipsec/ipsec.h>
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#include <netipsec/ipsec6.h>
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#include <netipsec/key.h>
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#include <netipsec/xform.h>
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#endif /* IPSEC */
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#include <net/net_osdep.h>
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struct route ip6_forward_rt;
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extern pfil_head_t *inet6_pfil_hook; /* XXX */
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/*
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* Forward a packet. If some error occurs return the sender
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* an icmp packet. Note we can't always generate a meaningful
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* icmp message because icmp doesn't have a large enough repertoire
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* of codes and types.
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*
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* If not forwarding, just drop the packet. This could be confusing
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* if ipforwarding was zero but some routing protocol was advancing
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* us as a gateway to somewhere. However, we must let the routing
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* protocol deal with that.
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*
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*/
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void
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ip6_forward(struct mbuf *m, int srcrt)
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{
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struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
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const struct sockaddr_in6 *dst;
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struct rtentry *rt;
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int error = 0, type = 0, code = 0;
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struct mbuf *mcopy = NULL;
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struct ifnet *origifp; /* maybe unnecessary */
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u_int32_t inzone, outzone;
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struct in6_addr src_in6, dst_in6;
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#ifdef IPSEC
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int needipsec = 0;
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struct secpolicy *sp = NULL;
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#endif
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/*
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* Clear any in-bound checksum flags for this packet.
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*/
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m->m_pkthdr.csum_flags = 0;
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/*
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* Do not forward packets to multicast destination (should be handled
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* by ip6_mforward().
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* Do not forward packets with unspecified source. It was discussed
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* in July 2000, on ipngwg mailing list.
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*/
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if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
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IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
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IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
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IP6_STATINC(IP6_STAT_CANTFORWARD);
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
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if (ip6_log_time + ip6_log_interval < time_second) {
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ip6_log_time = time_second;
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log(LOG_DEBUG,
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"cannot forward "
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"from %s to %s nxt %d received on %s\n",
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ip6_sprintf(&ip6->ip6_src),
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ip6_sprintf(&ip6->ip6_dst),
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ip6->ip6_nxt,
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if_name(m->m_pkthdr.rcvif));
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}
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m_freem(m);
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return;
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}
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if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
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icmp6_error(m, ICMP6_TIME_EXCEEDED,
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ICMP6_TIME_EXCEED_TRANSIT, 0);
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return;
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}
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ip6->ip6_hlim -= IPV6_HLIMDEC;
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/*
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* Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
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* size of IPv6 + ICMPv6 headers) bytes of the packet in case
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* we need to generate an ICMP6 message to the src.
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* Thanks to M_EXT, in most cases copy will not occur.
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*
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* It is important to save it before IPsec processing as IPsec
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* processing may modify the mbuf.
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*/
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mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
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#ifdef IPSEC
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if (ipsec_used) {
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/* Check the security policy (SP) for the packet */
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sp = ipsec6_check_policy(m, NULL, 0, &needipsec, &error);
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if (error != 0) {
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/*
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* Hack: -EINVAL is used to signal that a packet
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* should be silently discarded. This is typically
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* because we asked key management for an SA and
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* it was delayed (e.g. kicked up to IKE).
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*/
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if (error == -EINVAL)
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error = 0;
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goto freecopy;
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}
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}
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#endif /* IPSEC */
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if (srcrt) {
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union {
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struct sockaddr dst;
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struct sockaddr_in6 dst6;
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} u;
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sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
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if ((rt = rtcache_lookup(&ip6_forward_rt, &u.dst)) == NULL) {
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IP6_STATINC(IP6_STAT_NOROUTE);
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
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if (mcopy) {
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_NOROUTE, 0);
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}
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m_freem(m);
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return;
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}
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} else if ((rt = rtcache_validate(&ip6_forward_rt)) == NULL &&
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(rt = rtcache_update(&ip6_forward_rt, 1)) == NULL) {
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/*
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* rtcache_getdst(ip6_forward_rt)->sin6_addr was equal to
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* ip6->ip6_dst
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*/
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IP6_STATINC(IP6_STAT_NOROUTE);
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
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if (mcopy) {
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_NOROUTE, 0);
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}
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m_freem(m);
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return;
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}
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dst = satocsin6(rtcache_getdst(&ip6_forward_rt));
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/*
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* Source scope check: if a packet can't be delivered to its
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* destination for the reason that the destination is beyond the scope
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* of the source address, discard the packet and return an icmp6
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* destination unreachable error with Code 2 (beyond scope of source
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* address). We use a local copy of ip6_src, since in6_setscope()
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* will possibly modify its first argument.
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* [draft-ietf-ipngwg-icmp-v3-07, Section 3.1]
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*/
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src_in6 = ip6->ip6_src;
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if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
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/* XXX: this should not happen */
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uint64_t *ip6s = IP6_STAT_GETREF();
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ip6s[IP6_STAT_CANTFORWARD]++;
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ip6s[IP6_STAT_BADSCOPE]++;
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IP6_STAT_PUTREF();
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m_freem(m);
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return;
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}
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if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
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uint64_t *ip6s = IP6_STAT_GETREF();
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ip6s[IP6_STAT_CANTFORWARD]++;
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ip6s[IP6_STAT_BADSCOPE]++;
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IP6_STAT_PUTREF();
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m_freem(m);
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return;
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}
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if (inzone != outzone) {
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uint64_t *ip6s = IP6_STAT_GETREF();
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ip6s[IP6_STAT_CANTFORWARD]++;
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ip6s[IP6_STAT_BADSCOPE]++;
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IP6_STAT_PUTREF();
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in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
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if (ip6_log_time + ip6_log_interval < time_second) {
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ip6_log_time = time_second;
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log(LOG_DEBUG,
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"cannot forward "
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"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
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ip6_sprintf(&ip6->ip6_src),
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ip6_sprintf(&ip6->ip6_dst),
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ip6->ip6_nxt,
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if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
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}
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if (mcopy)
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
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m_freem(m);
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return;
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}
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#ifdef IPSEC
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/*
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* If we need to encapsulate the packet, do it here
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* ipsec6_proces_packet will send the packet using ip6_output
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*/
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if (needipsec) {
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int s = splsoftnet();
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error = ipsec6_process_packet(m, sp->req);
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splx(s);
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if (mcopy)
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goto freecopy;
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}
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#endif
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/*
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* Destination scope check: if a packet is going to break the scope
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* zone of packet's destination address, discard it. This case should
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* usually be prevented by appropriately-configured routing table, but
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* we need an explicit check because we may mistakenly forward the
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* packet to a different zone by (e.g.) a default route.
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*/
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dst_in6 = ip6->ip6_dst;
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if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
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in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
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inzone != outzone) {
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uint64_t *ip6s = IP6_STAT_GETREF();
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ip6s[IP6_STAT_CANTFORWARD]++;
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ip6s[IP6_STAT_BADSCOPE]++;
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IP6_STAT_PUTREF();
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m_freem(m);
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return;
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}
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if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
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in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
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if (mcopy) {
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u_long mtu;
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mtu = IN6_LINKMTU(rt->rt_ifp);
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icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
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}
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m_freem(m);
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return;
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}
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if (rt->rt_flags & RTF_GATEWAY)
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dst = (struct sockaddr_in6 *)rt->rt_gateway;
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/*
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* If we are to forward the packet using the same interface
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* as one we got the packet from, perhaps we should send a redirect
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* to sender to shortcut a hop.
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* Only send redirect if source is sending directly to us,
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* and if packet was not source routed (or has any options).
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* Also, don't send redirect if forwarding using a route
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* modified by a redirect.
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*/
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if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && ip6_sendredirects &&
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(rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
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if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) &&
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nd6_is_addr_neighbor(
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satocsin6(rtcache_getdst(&ip6_forward_rt)),
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rt->rt_ifp)) {
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/*
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* If the incoming interface is equal to the outgoing
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* one, the link attached to the interface is
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* point-to-point, and the IPv6 destination is
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* regarded as on-link on the link, then it will be
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* highly probable that the destination address does
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* not exist on the link and that the packet is going
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* to loop. Thus, we immediately drop the packet and
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* send an ICMPv6 error message.
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* For other routing loops, we dare to let the packet
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* go to the loop, so that a remote diagnosing host
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* can detect the loop by traceroute.
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* type/code is based on suggestion by Rich Draves.
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* not sure if it is the best pick.
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*/
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_ADDR, 0);
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m_freem(m);
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return;
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}
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type = ND_REDIRECT;
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}
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/*
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* Fake scoped addresses. Note that even link-local source or
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* destinaion can appear, if the originating node just sends the
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* packet to us (without address resolution for the destination).
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* Since both icmp6_error and icmp6_redirect_output fill the embedded
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* link identifiers, we can do this stuff after making a copy for
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* returning an error.
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*/
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if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
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/*
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* See corresponding comments in ip6_output.
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* XXX: but is it possible that ip6_forward() sends a packet
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* to a loopback interface? I don't think so, and thus
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* I bark here. (jinmei@kame.net)
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* XXX: it is common to route invalid packets to loopback.
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* also, the codepath will be visited on use of ::1 in
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* rthdr. (itojun)
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*/
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#if 1
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if (0)
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#else
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if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
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#endif
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{
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printf("ip6_forward: outgoing interface is loopback. "
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"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
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ip6_sprintf(&ip6->ip6_src),
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ip6_sprintf(&ip6->ip6_dst),
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ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
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if_name(rt->rt_ifp));
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}
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/* we can just use rcvif in forwarding. */
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origifp = m->m_pkthdr.rcvif;
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}
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else
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origifp = rt->rt_ifp;
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/*
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* clear embedded scope identifiers if necessary.
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* in6_clearscope will touch the addresses only when necessary.
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*/
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in6_clearscope(&ip6->ip6_src);
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in6_clearscope(&ip6->ip6_dst);
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/*
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* Run through list of hooks for output packets.
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*/
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if ((error = pfil_run_hooks(inet6_pfil_hook, &m, rt->rt_ifp,
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PFIL_OUT)) != 0)
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goto senderr;
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if (m == NULL)
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goto freecopy;
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ip6 = mtod(m, struct ip6_hdr *);
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error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
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if (error) {
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in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
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IP6_STATINC(IP6_STAT_CANTFORWARD);
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} else {
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IP6_STATINC(IP6_STAT_FORWARD);
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in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
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if (type)
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IP6_STATINC(IP6_STAT_REDIRECTSENT);
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else {
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#ifdef GATEWAY
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if (m->m_flags & M_CANFASTFWD)
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ip6flow_create(&ip6_forward_rt, m);
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#endif
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if (mcopy)
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goto freecopy;
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}
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}
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senderr:
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if (mcopy == NULL)
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return;
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switch (error) {
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case 0:
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if (type == ND_REDIRECT) {
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icmp6_redirect_output(mcopy, rt);
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return;
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}
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goto freecopy;
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case EMSGSIZE:
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/* xxx MTU is constant in PPP? */
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goto freecopy;
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case ENOBUFS:
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/* Tell source to slow down like source quench in IP? */
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goto freecopy;
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case ENETUNREACH: /* shouldn't happen, checked above */
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case EHOSTUNREACH:
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case ENETDOWN:
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case EHOSTDOWN:
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default:
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type = ICMP6_DST_UNREACH;
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code = ICMP6_DST_UNREACH_ADDR;
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break;
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}
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icmp6_error(mcopy, type, code, 0);
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return;
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freecopy:
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m_freem(mcopy);
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return;
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}
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