457 lines
11 KiB
C
457 lines
11 KiB
C
/* $NetBSD: ip6_forward.c,v 1.7 2000/01/31 14:19:03 itojun 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/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 <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 <netinet6/ip6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/icmp6.h>
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#include <netinet6/nd6.h>
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#ifdef IPSEC_IPV6FWD
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#include <netinet6/ipsec.h>
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#include <netkey/key.h>
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#include <netkey/key_debug.h>
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#endif /* IPSEC_IPV6FWD */
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#ifdef IPV6FIREWALL
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#include <netinet6/ip6_fw.h>
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#endif
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#include <net/net_osdep.h>
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struct route_in6 ip6_forward_rt;
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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(m, srcrt)
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struct mbuf *m;
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int srcrt;
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{
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struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
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register struct sockaddr_in6 *dst;
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register struct rtentry *rt;
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int error, type = 0, code = 0;
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struct mbuf *mcopy = NULL;
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#ifdef IPSEC_IPV6FWD
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struct secpolicy *sp = NULL;
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#endif
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long time_second = time.tv_sec;
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#ifdef IPSEC_IPV6FWD
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/*
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* Check AH/ESP integrity.
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*/
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/*
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* Don't increment ip6s_cantforward because this is the check
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* before forwarding packet actually.
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*/
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if (ipsec6_in_reject(m, NULL)) {
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ipsec6stat.in_polvio++;
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m_freem(m);
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return;
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}
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#endif /*IPSEC_IPV6FWD*/
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if (m->m_flags & (M_BCAST|M_MCAST) ||
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in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) {
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ip6stat.ip6s_cantforward++;
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ip6stat.ip6s_badscope++;
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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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char addr[INET6_ADDRSTRLEN];
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ip6_log_time = time_second;
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strncpy(addr, ip6_sprintf(&ip6->ip6_src), sizeof(addr));
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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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addr, 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_IPV6FWD
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/* get a security policy for this packet */
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sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error);
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if (sp == NULL) {
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ipsec6stat.out_inval++;
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ip6stat.ip6s_cantforward++;
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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error = 0;
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/* check policy */
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switch (sp->policy) {
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case IPSEC_POLICY_DISCARD:
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/*
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* This packet is just discarded.
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*/
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ipsec6stat.out_polvio++;
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ip6stat.ip6s_cantforward++;
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key_freesp(sp);
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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case IPSEC_POLICY_BYPASS:
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case IPSEC_POLICY_NONE:
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/* no need to do IPsec. */
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key_freesp(sp);
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goto skip_ipsec;
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case IPSEC_POLICY_IPSEC:
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if (sp->req == NULL) {
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/* XXX should be panic ? */
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printf("ip6_forward: No IPsec request specified.\n");
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ip6stat.ip6s_cantforward++;
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key_freesp(sp);
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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/* do IPsec */
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break;
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case IPSEC_POLICY_ENTRUST:
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default:
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/* should be panic ?? */
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printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
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key_freesp(sp);
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goto skip_ipsec;
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}
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{
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struct ipsec_output_state state;
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/*
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* All the extension headers will become inaccessible
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* (since they can be encrypted).
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* Don't panic, we need no more updates to extension headers
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* on inner IPv6 packet (since they are now encapsulated).
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*
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* IPv6 [ESP|AH] IPv6 [extension headers] payload
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*/
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bzero(&state, sizeof(state));
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state.m = m;
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state.ro = NULL; /* update at ipsec6_output_tunnel() */
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state.dst = NULL; /* update at ipsec6_output_tunnel() */
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error = ipsec6_output_tunnel(&state, sp, 0);
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m = state.m;
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#if 0 /* XXX allocate a route (ro, dst) again later */
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ro = (struct route_in6 *)state.ro;
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dst = (struct sockaddr_in6 *)state.dst;
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#endif
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key_freesp(sp);
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if (error) {
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/* mbuf is already reclaimed in ipsec6_output_tunnel. */
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switch (error) {
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case EHOSTUNREACH:
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case ENETUNREACH:
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case EMSGSIZE:
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case ENOBUFS:
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case ENOMEM:
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break;
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default:
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printf("ip6_output (ipsec): error code %d\n", error);
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/*fall through*/
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case ENOENT:
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/* don't show these error codes to the user */
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break;
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}
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ip6stat.ip6s_cantforward++;
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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}
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skip_ipsec:
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#endif /* IPSEC_IPV6FWD */
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dst = &ip6_forward_rt.ro_dst;
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if (!srcrt) {
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/*
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* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
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*/
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if (ip6_forward_rt.ro_rt == 0 ||
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(ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
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if (ip6_forward_rt.ro_rt) {
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RTFREE(ip6_forward_rt.ro_rt);
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ip6_forward_rt.ro_rt = 0;
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}
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/* this probably fails but give it a try again */
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rtalloc((struct route *)&ip6_forward_rt);
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}
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if (ip6_forward_rt.ro_rt == 0) {
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ip6stat.ip6s_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 = ip6_forward_rt.ro_rt) == 0 ||
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!IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
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if (ip6_forward_rt.ro_rt) {
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RTFREE(ip6_forward_rt.ro_rt);
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ip6_forward_rt.ro_rt = 0;
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}
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bzero(dst, sizeof(*dst));
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dst->sin6_len = sizeof(struct sockaddr_in6);
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dst->sin6_family = AF_INET6;
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dst->sin6_addr = ip6->ip6_dst;
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rtalloc((struct route *)&ip6_forward_rt);
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if (ip6_forward_rt.ro_rt == 0) {
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ip6stat.ip6s_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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}
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rt = ip6_forward_rt.ro_rt;
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if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
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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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#ifdef IPSEC_IPV6FWD
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struct secpolicy *sp;
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int ipsecerror;
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size_t ipsechdrsiz;
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#endif
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mtu = rt->rt_ifp->if_mtu;
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#ifdef IPSEC_IPV6FWD
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/*
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* When we do IPsec tunnel ingress, we need to play
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* with if_mtu value (decrement IPsec header size
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* from mtu value). The code is much simpler than v4
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* case, as we have the outgoing interface for
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* encapsulated packet as "rt->rt_ifp".
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*/
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sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
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IP_FORWARDING, &ipsecerror);
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if (sp) {
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ipsechdrsiz = ipsec6_hdrsiz(mcopy,
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IPSEC_DIR_OUTBOUND, NULL);
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if (ipsechdrsiz < mtu)
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mtu -= ipsechdrsiz;
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}
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/*
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* if mtu becomes less than minimum MTU,
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* tell minimum MTU (and I'll need to fragment it).
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*/
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if (mtu < IPV6_MMTU)
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mtu = IPV6_MMTU;
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#endif
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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 &&
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(rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0)
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type = ND_REDIRECT;
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#ifdef IPV6FIREWALL
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/*
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* Check with the firewall...
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*/
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if (ip6_fw_chk_ptr) {
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u_short port = 0;
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/* If ipfw says divert, we have to just drop packet */
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if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
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m_freem(m);
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goto freecopy;
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}
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if (!m)
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goto freecopy;
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}
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#endif
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#ifdef OLDIP6OUTPUT
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error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m,
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(struct sockaddr *)dst,
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ip6_forward_rt.ro_rt);
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#else
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error = nd6_output(rt->rt_ifp, m, dst, rt);
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#endif
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if (error) {
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in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
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ip6stat.ip6s_cantforward++;
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} else {
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ip6stat.ip6s_forward++;
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in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
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if (type)
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ip6stat.ip6s_redirectsent++;
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else {
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if (mcopy)
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goto freecopy;
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}
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}
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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 1
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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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#endif
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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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