[apple/xnu.git] / bsd / netinet6 / ip6_forward.c

/*	$KAME: ip6_forward.c,v 1.29 2000/02/26 18:08:38 itojun Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if (defined(__FreeBSD__) && __FreeBSD__ >= 3)
#include "opt_ip6fw.h"
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>

#if IPSEC_IPV6FWD
#include <netinet6/ipsec.h>
#include <netkey/key.h>
#include <netkey/key_debug.h>
#endif /* IPSEC_IPV6FWD */

#if IPV6FIREWALL
#include <netinet6/ip6_fw.h>
#endif

#if MIP6
#include <netinet6/mip6.h>
#endif

#include <net/net_osdep.h>

struct	route_in6 ip6_forward_rt;

/*
 * Forward a packet.  If some error occurs return the sender
 * an icmp packet.  Note we can't always generate a meaningful
 * icmp message because icmp doesn't have a large enough repertoire
 * of codes and types.
 *
 * If not forwarding, just drop the packet.  This could be confusing
 * if ipforwarding was zero but some routing protocol was advancing
 * us as a gateway to somewhere.  However, we must let the routing
 * protocol deal with that.
 *
 */

void
ip6_forward(m, srcrt)
	struct mbuf *m;
	int srcrt;
{
	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
	register struct sockaddr_in6 *dst;
	register struct rtentry *rt;
	int error, type = 0, code = 0;
	struct mbuf *mcopy = NULL;
#if IPSEC_IPV6FWD
	struct secpolicy *sp = NULL;
#endif
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3) && !defined(__APPLE__)
	long time_second = time.tv_sec;
#endif

#if IPSEC_IPV6FWD
	/*
	 * Check AH/ESP integrity.
	 */
	/*
	 * Don't increment ip6s_cantforward because this is the check
	 * before forwarding packet actually.
	 */
	if (ipsec6_in_reject(m, NULL)) {
		ipsec6stat.in_polvio++;
		m_freem(m);
		return;
	}
#endif /*IPSEC_IPV6FWD*/

	if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
		ip6stat.ip6s_cantforward++;
		/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
		if (ip6_log_time + ip6_log_interval < time_second) {
			ip6_log_time = time_second;
			log(LOG_DEBUG,
			    "cannot forward "
			    "from %s to %s nxt %d received on %s\n",
			    ip6_sprintf(&ip6->ip6_src),
			    ip6_sprintf(&ip6->ip6_dst),
			    ip6->ip6_nxt,
			    if_name(m->m_pkthdr.rcvif));
		}
		m_freem(m);
		return;
	}

	if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
		/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
		icmp6_error(m, ICMP6_TIME_EXCEEDED,
				ICMP6_TIME_EXCEED_TRANSIT, 0);
		return;
	}
	ip6->ip6_hlim -= IPV6_HLIMDEC;

	/*
	 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
	 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
	 * we need to generate an ICMP6 message to the src.
	 * Thanks to M_EXT, in most cases copy will not occur.
	 *
	 * It is important to save it before IPsec processing as IPsec
	 * processing may modify the mbuf.
	 */
	mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));


#if IPSEC_IPV6FWD
	/* get a security policy for this packet */
	sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error);
	if (sp == NULL) {
		ipsec6stat.out_inval++;
		ip6stat.ip6s_cantforward++;
		if (mcopy) {
#if 0
			/* XXX: what icmp ? */
#else
			m_freem(mcopy);
#endif
		}
		m_freem(m);
		return;
	}

	error = 0;

	/* check policy */
	switch (sp->policy) {
	case IPSEC_POLICY_DISCARD:
		/*
		 * This packet is just discarded.
		 */
		ipsec6stat.out_polvio++;
		ip6stat.ip6s_cantforward++;
		key_freesp(sp);
		if (mcopy) {
#if 0
			/* XXX: what icmp ? */
#else
			m_freem(mcopy);
#endif
		}
		m_freem(m);
		return;

	case IPSEC_POLICY_BYPASS:
	case IPSEC_POLICY_NONE:
		/* no need to do IPsec. */
		key_freesp(sp);
		goto skip_ipsec;
	
	case IPSEC_POLICY_IPSEC:
		if (sp->req == NULL) {
			/* XXX should be panic ? */
			printf("ip6_forward: No IPsec request specified.\n");
			ip6stat.ip6s_cantforward++;
			key_freesp(sp);
			if (mcopy) {
#if 0
				/* XXX: what icmp ? */
#else
				m_freem(mcopy);
#endif
			}
			m_freem(m);
			return;
		}
		/* do IPsec */
		break;

	case IPSEC_POLICY_ENTRUST:
	default:
		/* should be panic ?? */
		printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
		key_freesp(sp);
		goto skip_ipsec;
	}

    {
	struct ipsec_output_state state;

	/*
	 * All the extension headers will become inaccessible
	 * (since they can be encrypted).
	 * Don't panic, we need no more updates to extension headers
	 * on inner IPv6 packet (since they are now encapsulated).
	 *
	 * IPv6 [ESP|AH] IPv6 [extension headers] payload
	 */
	bzero(&state, sizeof(state));
	state.m = m;
	state.ro = NULL;	/* update at ipsec6_output_tunnel() */
	state.dst = NULL;	/* update at ipsec6_output_tunnel() */

	error = ipsec6_output_tunnel(&state, sp, 0);

	m = state.m;
#if 0	/* XXX allocate a route (ro, dst) again later */
	ro = (struct route_in6 *)state.ro;
	dst = (struct sockaddr_in6 *)state.dst;
#endif
	key_freesp(sp);

	if (error) {
		/* mbuf is already reclaimed in ipsec6_output_tunnel. */
		switch (error) {
		case EHOSTUNREACH:
		case ENETUNREACH:
		case EMSGSIZE:
		case ENOBUFS:
		case ENOMEM:
			break;
		default:
			printf("ip6_output (ipsec): error code %d\n", error);
			/*fall through*/
		case ENOENT:
			/* don't show these error codes to the user */
			break;
		}
		ip6stat.ip6s_cantforward++;
		if (mcopy) {
#if 0
			/* XXX: what icmp ? */
#else
			m_freem(mcopy);
#endif
		}
		m_freem(m);
		return;
	}
    }
    skip_ipsec:
#endif /* IPSEC_IPV6FWD */
	
#if MIP6
	{
		struct   mip6_bc   *bc;

		bc = mip6_bc_find(&ip6->ip6_dst);
		if ((bc != NULL) && (bc->hr_flag)) {
			if (mip6_tunnel_output(&m, bc) != 0) {
				ip6stat.ip6s_cantforward++;
				if (mcopy)
					m_freem(mcopy);
				m_freem(m);
				return;
			}
		}
		ip6 = mtod(m, struct ip6_hdr *);	/* m has changed */
	}
#endif
	
	dst = &ip6_forward_rt.ro_dst;
	if (!srcrt) {
		/*
		 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
		 */
		if (ip6_forward_rt.ro_rt == 0 ||
		    (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
			if (ip6_forward_rt.ro_rt) {
				RTFREE(ip6_forward_rt.ro_rt);
				ip6_forward_rt.ro_rt = 0;
			}
			/* this probably fails but give it a try again */
#if __FreeBSD__ || defined(__APPLE__)
			rtalloc_ign((struct route *)&ip6_forward_rt,
				    RTF_PRCLONING);
#else
			rtalloc((struct route *)&ip6_forward_rt);
#endif
		}
		
		if (ip6_forward_rt.ro_rt == 0) {
			ip6stat.ip6s_noroute++;
			/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
			if (mcopy) {
				icmp6_error(mcopy, ICMP6_DST_UNREACH,
					    ICMP6_DST_UNREACH_NOROUTE, 0);
			}
			m_freem(m);
			return;
		}
	} else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
		 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
		if (ip6_forward_rt.ro_rt) {
			RTFREE(ip6_forward_rt.ro_rt);
			ip6_forward_rt.ro_rt = 0;
		}
		bzero(dst, sizeof(*dst));
		dst->sin6_len = sizeof(struct sockaddr_in6);
		dst->sin6_family = AF_INET6;
		dst->sin6_addr = ip6->ip6_dst;

#if __FreeBSD__ || defined(__APPLE__)
  		rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
#else
		rtalloc((struct route *)&ip6_forward_rt);
#endif
		if (ip6_forward_rt.ro_rt == 0) {
			ip6stat.ip6s_noroute++;
			/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
			if (mcopy) {
				icmp6_error(mcopy, ICMP6_DST_UNREACH,
					    ICMP6_DST_UNREACH_NOROUTE, 0);
			}
			m_freem(m);
			return;
		}
	}
	rt = ip6_forward_rt.ro_rt;

	/*
	 * Scope check: if a packet can't be delivered to its destination
	 * for the reason that the destination is beyond the scope of the
	 * source address, discard the packet and return an icmp6 destination
	 * unreachable error with Code 2 (beyond scope of source address).
	 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1]
	 */
	if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
	    in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
		ip6stat.ip6s_cantforward++;
		ip6stat.ip6s_badscope++;
		in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);

		if (ip6_log_time + ip6_log_interval < time_second) {
			ip6_log_time = time_second;
			log(LOG_DEBUG,
			    "cannot forward "
			    "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
			    ip6_sprintf(&ip6->ip6_src),
			    ip6_sprintf(&ip6->ip6_dst),
			    ip6->ip6_nxt,
			    if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
		}
		if (mcopy)
			icmp6_error(mcopy, ICMP6_DST_UNREACH,
				    ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
		m_freem(m);
		return;
	}

	if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
		in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
		if (mcopy) {
			u_long mtu;
#if IPSEC_IPV6FWD
			struct secpolicy *sp;
			int ipsecerror;
			size_t ipsechdrsiz;
#endif

			mtu = rt->rt_ifp->if_mtu;
#if IPSEC_IPV6FWD
			/*
			 * When we do IPsec tunnel ingress, we need to play
			 * with if_mtu value (decrement IPsec header size
			 * from mtu value).  The code is much simpler than v4
			 * case, as we have the outgoing interface for
			 * encapsulated packet as "rt->rt_ifp".
			 */
			sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
				IP_FORWARDING, &ipsecerror);
			if (sp) {
				ipsechdrsiz = ipsec6_hdrsiz(mcopy,
					IPSEC_DIR_OUTBOUND, NULL);
				if (ipsechdrsiz < mtu)
					mtu -= ipsechdrsiz;
			}

			/*
			 * if mtu becomes less than minimum MTU,
			 * tell minimum MTU (and I'll need to fragment it).
			 */
			if (mtu < IPV6_MMTU)
				mtu = IPV6_MMTU;
#endif
			icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
		}
		m_freem(m);
		return;
 	}

	if (rt->rt_flags & RTF_GATEWAY)
		dst = (struct sockaddr_in6 *)rt->rt_gateway;

	/*
	 * If we are to forward the packet using the same interface
	 * as one we got the packet from, perhaps we should send a redirect
	 * to sender to shortcut a hop.
	 * Only send redirect if source is sending directly to us,
	 * and if packet was not source routed (or has any options).
	 * Also, don't send redirect if forwarding using a route
	 * modified by a redirect.
	 */
	if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0)
		type = ND_REDIRECT;

#if IPV6FIREWALL
	/*
	 * Check with the firewall...
	 */
	if (ip6_fw_chk_ptr) {
		u_short port = 0;
		/* If ipfw says divert, we have to just drop packet */
		if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
			m_freem(m);
			goto freecopy;
		}
		if (!m)
			goto freecopy;
	}
#endif

#if OLDIP6OUTPUT
	error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m,
					 (struct sockaddr *)dst,
					 ip6_forward_rt.ro_rt);
#else
	error = nd6_output(rt->rt_ifp, m, dst, rt);
#endif 
	if (error) {
		in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
		ip6stat.ip6s_cantforward++;
	} else {
		ip6stat.ip6s_forward++;
		in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
		if (type)
			ip6stat.ip6s_redirectsent++;
		else {
			if (mcopy)
				goto freecopy;
		}
	}
	if (mcopy == NULL)
		return;

	switch (error) {
	case 0:
#if 1
		if (type == ND_REDIRECT) {
			icmp6_redirect_output(mcopy, rt);
			return;
		}
#endif
		goto freecopy;

	case EMSGSIZE:
		/* xxx MTU is constant in PPP? */
		goto freecopy;

	case ENOBUFS:
		/* Tell source to slow down like source quench in IP? */
		goto freecopy;

	case ENETUNREACH:	/* shouldn't happen, checked above */
	case EHOSTUNREACH:
	case ENETDOWN:
	case EHOSTDOWN:
	default:
		type = ICMP6_DST_UNREACH;
		code = ICMP6_DST_UNREACH_ADDR;
		break;
	}
	icmp6_error(mcopy, type, code, 0);
	return;

 freecopy:
	m_freem(mcopy);
	return;
}
Commit	Line	Data
1c79356b A	1	/* $KAME: ip6_forward.c,v 1.29 2000/02/26 18:08:38 itojun Exp $ */
	2
	3	/*
	4	* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
	5	* All rights reserved.
	6	*
	7	* Redistribution and use in source and binary forms, with or without
	8	* modification, are permitted provided that the following conditions
	9	* are met:
	10	* 1. Redistributions of source code must retain the above copyright
	11	* notice, this list of conditions and the following disclaimer.
	12	* 2. Redistributions in binary form must reproduce the above copyright
	13	* notice, this list of conditions and the following disclaimer in the
	14	* documentation and/or other materials provided with the distribution.
	15	* 3. Neither the name of the project nor the names of its contributors
	16	* may be used to endorse or promote products derived from this software
	17	* without specific prior written permission.
	18	*
	19	* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	20	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	21	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	22	* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	23	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	24	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	25	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	26	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	27	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	28	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	29	* SUCH DAMAGE.
	30	*/
	31
	32	#if (defined(__FreeBSD__) && __FreeBSD__ >= 3)
	33	#include "opt_ip6fw.h"
	34	#include "opt_inet.h"
	35	#endif
	36
	37	#include <sys/param.h>
	38	#include <sys/systm.h>
	39	#include <sys/malloc.h>
	40	#include <sys/mbuf.h>
	41	#include <sys/domain.h>
	42	#include <sys/protosw.h>
	43	#include <sys/socket.h>
	44	#include <sys/errno.h>
	45	#include <sys/time.h>
	46	#include <sys/kernel.h>
	47	#include <sys/syslog.h>
	48
	49	#include <net/if.h>
	50	#include <net/route.h>
	51
	52	#include <netinet/in.h>
	53	#include <netinet/in_var.h>
	54	#include <netinet/ip_var.h>
	55	#include <netinet/ip6.h>
	56	#include <netinet6/ip6_var.h>
	57	#include <netinet/icmp6.h>
	58	#include <netinet6/nd6.h>
	59
	60	#if IPSEC_IPV6FWD
	61	#include <netinet6/ipsec.h>
	62	#include <netkey/key.h>
	63	#include <netkey/key_debug.h>
	64	#endif /* IPSEC_IPV6FWD */
65
66	#if IPV6FIREWALL
67	#include <netinet6/ip6_fw.h>
68	#endif
69
70	#if MIP6
71	#include <netinet6/mip6.h>
72	#endif
73
74	#include <net/net_osdep.h>
75
76	struct route_in6 ip6_forward_rt;
77
78	/*
79	* Forward a packet. If some error occurs return the sender
80	* an icmp packet. Note we can't always generate a meaningful
81	* icmp message because icmp doesn't have a large enough repertoire
82	* of codes and types.
83	*
84	* If not forwarding, just drop the packet. This could be confusing
85	* if ipforwarding was zero but some routing protocol was advancing
86	* us as a gateway to somewhere. However, we must let the routing
87	* protocol deal with that.
88	*
89	*/
90
91	void
92	ip6_forward(m, srcrt)
93	struct mbuf *m;
94	int srcrt;
95	{
96	struct ip6_hdr ip6 = mtod(m, struct ip6_hdr );
97	register struct sockaddr_in6 *dst;
98	register struct rtentry *rt;
99	int error, type = 0, code = 0;
100	struct mbuf *mcopy = NULL;
101	#if IPSEC_IPV6FWD
102	struct secpolicy *sp = NULL;
103	#endif
104	#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3) && !defined(__APPLE__)
105	long time_second = time.tv_sec;
106	#endif
107
108	#if IPSEC_IPV6FWD
109	/*
110	* Check AH/ESP integrity.
111	*/
112	/*
113	* Don't increment ip6s_cantforward because this is the check
114	* before forwarding packet actually.
115	*/
116	if (ipsec6_in_reject(m, NULL)) {
117	ipsec6stat.in_polvio++;
118	m_freem(m);
119	return;
120	}
121	#endif /IPSEC_IPV6FWD/
122
123	if ((m->m_flags & (M_BCAST\|M_MCAST)) != 0 \|\|
124	IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
125	ip6stat.ip6s_cantforward++;
126	/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
127	if (ip6_log_time + ip6_log_interval < time_second) {
128	ip6_log_time = time_second;
129	log(LOG_DEBUG,
130	"cannot forward "
131	"from %s to %s nxt %d received on %s\n",
132	ip6_sprintf(&ip6->ip6_src),
133	ip6_sprintf(&ip6->ip6_dst),
134	ip6->ip6_nxt,
135	if_name(m->m_pkthdr.rcvif));
136	}
137	m_freem(m);
138	return;
139	}
140
141	if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
142	/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
143	icmp6_error(m, ICMP6_TIME_EXCEEDED,
144	ICMP6_TIME_EXCEED_TRANSIT, 0);
145	return;
146	}
147	ip6->ip6_hlim -= IPV6_HLIMDEC;
148
149	/*
150	* Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
151	* size of IPv6 + ICMPv6 headers) bytes of the packet in case
152	* we need to generate an ICMP6 message to the src.
153	* Thanks to M_EXT, in most cases copy will not occur.
154	*
155	* It is important to save it before IPsec processing as IPsec
156	* processing may modify the mbuf.
157	*/
158	mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
159
160
161	#if IPSEC_IPV6FWD
162	/* get a security policy for this packet */
163	sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error);
164	if (sp == NULL) {
165	ipsec6stat.out_inval++;
166	ip6stat.ip6s_cantforward++;
167	if (mcopy) {
168	#if 0
169	/* XXX: what icmp ? */
170	#else
171	m_freem(mcopy);
172	#endif
173	}
174	m_freem(m);
175	return;
176	}
177
178	error = 0;
179
180	/* check policy */
181	switch (sp->policy) {
182	case IPSEC_POLICY_DISCARD:
183	/*
184	* This packet is just discarded.
185	*/
186	ipsec6stat.out_polvio++;
187	ip6stat.ip6s_cantforward++;
188	key_freesp(sp);
189	if (mcopy) {
190	#if 0
191	/* XXX: what icmp ? */
192	#else
193	m_freem(mcopy);
194	#endif
195	}
196	m_freem(m);
197	return;
198
199	case IPSEC_POLICY_BYPASS:
200	case IPSEC_POLICY_NONE:
201	/* no need to do IPsec. */
202	key_freesp(sp);
203	goto skip_ipsec;
204
205	case IPSEC_POLICY_IPSEC:
206	if (sp->req == NULL) {
207	/* XXX should be panic ? */
208	printf("ip6_forward: No IPsec request specified.\n");
209	ip6stat.ip6s_cantforward++;
210	key_freesp(sp);
211	if (mcopy) {
212	#if 0
213	/* XXX: what icmp ? */
214	#else
215	m_freem(mcopy);
216	#endif
217	}
218	m_freem(m);
219	return;
220	}
221	/* do IPsec */
222	break;
223
224	case IPSEC_POLICY_ENTRUST:
225	default:
226	/* should be panic ?? */
227	printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
228	key_freesp(sp);
229	goto skip_ipsec;
230	}
231
232	{
233	struct ipsec_output_state state;
234
235	/*
236	* All the extension headers will become inaccessible
237	* (since they can be encrypted).
238	* Don't panic, we need no more updates to extension headers
239	* on inner IPv6 packet (since they are now encapsulated).
240	*
241	* IPv6 [ESP\|AH] IPv6 [extension headers] payload
242	*/
243	bzero(&state, sizeof(state));
244	state.m = m;
245	state.ro = NULL; /* update at ipsec6_output_tunnel() */
246	state.dst = NULL; /* update at ipsec6_output_tunnel() */
247
248	error = ipsec6_output_tunnel(&state, sp, 0);
249
250	m = state.m;
251	#if 0 /* XXX allocate a route (ro, dst) again later */
252	ro = (struct route_in6 *)state.ro;
253	dst = (struct sockaddr_in6 *)state.dst;
254	#endif
255	key_freesp(sp);
256
257	if (error) {
258	/* mbuf is already reclaimed in ipsec6_output_tunnel. */
259	switch (error) {
260	case EHOSTUNREACH:
261	case ENETUNREACH:
262	case EMSGSIZE:
263	case ENOBUFS:
264	case ENOMEM:
265	break;
266	default:
267	printf("ip6_output (ipsec): error code %d\n", error);
268	/fall through/
269	case ENOENT:
270	/* don't show these error codes to the user */
271	break;
272	}
273	ip6stat.ip6s_cantforward++;
274	if (mcopy) {
275	#if 0
276	/* XXX: what icmp ? */
277	#else
278	m_freem(mcopy);
279	#endif
280	}
281	m_freem(m);
282	return;
283	}
284	}
285	skip_ipsec:
286	#endif /* IPSEC_IPV6FWD */
287
288	#if MIP6
289	{
290	struct mip6_bc *bc;
291
292	bc = mip6_bc_find(&ip6->ip6_dst);
293	if ((bc != NULL) && (bc->hr_flag)) {
294	if (mip6_tunnel_output(&m, bc) != 0) {
295	ip6stat.ip6s_cantforward++;
296	if (mcopy)
297	m_freem(mcopy);
298	m_freem(m);
299	return;
300	}
301	}
302	ip6 = mtod(m, struct ip6_hdr ); / m has changed */
303	}
304	#endif
305
306	dst = &ip6_forward_rt.ro_dst;
307	if (!srcrt) {
308	/*
309	* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
310	*/
311	if (ip6_forward_rt.ro_rt == 0 \|\|
312	(ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
313	if (ip6_forward_rt.ro_rt) {
314	RTFREE(ip6_forward_rt.ro_rt);
315	ip6_forward_rt.ro_rt = 0;
316	}
317	/* this probably fails but give it a try again */
318	#if __FreeBSD__ \|\| defined(__APPLE__)
319	rtalloc_ign((struct route *)&ip6_forward_rt,
320	RTF_PRCLONING);
321	#else
322	rtalloc((struct route *)&ip6_forward_rt);
323	#endif
324	}
325
326	if (ip6_forward_rt.ro_rt == 0) {
327	ip6stat.ip6s_noroute++;
328	/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
329	if (mcopy) {
330	icmp6_error(mcopy, ICMP6_DST_UNREACH,
331	ICMP6_DST_UNREACH_NOROUTE, 0);
332	}
333	m_freem(m);
334	return;
335	}
336	} else if ((rt = ip6_forward_rt.ro_rt) == 0 \|\|
337	!IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
338	if (ip6_forward_rt.ro_rt) {
339	RTFREE(ip6_forward_rt.ro_rt);
340	ip6_forward_rt.ro_rt = 0;
341	}
342	bzero(dst, sizeof(*dst));
343	dst->sin6_len = sizeof(struct sockaddr_in6);
344	dst->sin6_family = AF_INET6;
345	dst->sin6_addr = ip6->ip6_dst;
346
347	#if __FreeBSD__ \|\| defined(__APPLE__)
348	rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
349	#else
350	rtalloc((struct route *)&ip6_forward_rt);
351	#endif
352	if (ip6_forward_rt.ro_rt == 0) {
353	ip6stat.ip6s_noroute++;
354	/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
355	if (mcopy) {
356	icmp6_error(mcopy, ICMP6_DST_UNREACH,
357	ICMP6_DST_UNREACH_NOROUTE, 0);
358	}
359	m_freem(m);
360	return;
361	}
362	}
363	rt = ip6_forward_rt.ro_rt;
364
365	/*
366	* Scope check: if a packet can't be delivered to its destination
367	* for the reason that the destination is beyond the scope of the
368	* source address, discard the packet and return an icmp6 destination
369	* unreachable error with Code 2 (beyond scope of source address).
370	* [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1]
371	*/
372	if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
373	in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
374	ip6stat.ip6s_cantforward++;
375	ip6stat.ip6s_badscope++;
376	in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
377
378	if (ip6_log_time + ip6_log_interval < time_second) {
379	ip6_log_time = time_second;
380	log(LOG_DEBUG,
381	"cannot forward "
382	"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
383	ip6_sprintf(&ip6->ip6_src),
384	ip6_sprintf(&ip6->ip6_dst),
385	ip6->ip6_nxt,
386	if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
387	}
388	if (mcopy)
389	icmp6_error(mcopy, ICMP6_DST_UNREACH,
390	ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
391	m_freem(m);
392	return;
393	}
394
395	if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
396	in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
397	if (mcopy) {
398	u_long mtu;
399	#if IPSEC_IPV6FWD
400	struct secpolicy *sp;
401	int ipsecerror;
402	size_t ipsechdrsiz;
403	#endif
404
405	mtu = rt->rt_ifp->if_mtu;
406	#if IPSEC_IPV6FWD
407	/*
408	* When we do IPsec tunnel ingress, we need to play
409	* with if_mtu value (decrement IPsec header size
410	* from mtu value). The code is much simpler than v4
411	* case, as we have the outgoing interface for
412	* encapsulated packet as "rt->rt_ifp".
413	*/
414	sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
415	IP_FORWARDING, &ipsecerror);
416	if (sp) {
417	ipsechdrsiz = ipsec6_hdrsiz(mcopy,
418	IPSEC_DIR_OUTBOUND, NULL);
419	if (ipsechdrsiz < mtu)
420	mtu -= ipsechdrsiz;
421	}
422
423	/*
424	* if mtu becomes less than minimum MTU,
425	* tell minimum MTU (and I'll need to fragment it).
426	*/
427	if (mtu < IPV6_MMTU)
428	mtu = IPV6_MMTU;
429	#endif
430	icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
431	}
432	m_freem(m);
433	return;
434	}
435
436	if (rt->rt_flags & RTF_GATEWAY)
437	dst = (struct sockaddr_in6 *)rt->rt_gateway;
438
439	/*
440	* If we are to forward the packet using the same interface
441	* as one we got the packet from, perhaps we should send a redirect
442	* to sender to shortcut a hop.
443	* Only send redirect if source is sending directly to us,
444	* and if packet was not source routed (or has any options).
445	* Also, don't send redirect if forwarding using a route
446	* modified by a redirect.
447	*/
448	if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
449	(rt->rt_flags & (RTF_DYNAMIC\|RTF_MODIFIED)) == 0)
450	type = ND_REDIRECT;
451
452	#if IPV6FIREWALL
453	/*
454	* Check with the firewall...
455	*/
456	if (ip6_fw_chk_ptr) {
457	u_short port = 0;
458	/* If ipfw says divert, we have to just drop packet */
459	if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
460	m_freem(m);
461	goto freecopy;
462	}
463	if (!m)
464	goto freecopy;
465	}
466	#endif
467
468	#if OLDIP6OUTPUT
469	error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m,
470	(struct sockaddr *)dst,
471	ip6_forward_rt.ro_rt);
472	#else
473	error = nd6_output(rt->rt_ifp, m, dst, rt);
474	#endif
475	if (error) {
476	in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
477	ip6stat.ip6s_cantforward++;
478	} else {
479	ip6stat.ip6s_forward++;
480	in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
481	if (type)
482	ip6stat.ip6s_redirectsent++;
483	else {
484	if (mcopy)
485	goto freecopy;
486	}
487	}
488	if (mcopy == NULL)
489	return;
490
491	switch (error) {
492	case 0:
493	#if 1
494	if (type == ND_REDIRECT) {
495	icmp6_redirect_output(mcopy, rt);
496	return;
497	}
498	#endif
499	goto freecopy;
500
501	case EMSGSIZE:
502	/* xxx MTU is constant in PPP? */
503	goto freecopy;
504
505	case ENOBUFS:
506	/* Tell source to slow down like source quench in IP? */
507	goto freecopy;
508
509	case ENETUNREACH: /* shouldn't happen, checked above */
510	case EHOSTUNREACH:
511	case ENETDOWN:
512	case EHOSTDOWN:
513	default:
514	type = ICMP6_DST_UNREACH;
515	code = ICMP6_DST_UNREACH_ADDR;
516	break;
517	}
518	icmp6_error(mcopy, type, code, 0);
519	return;
520
521	freecopy:
522	m_freem(mcopy);
523	return;
524	}