NetBSD/sys/netinet6/ip6_forward.c

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/* $NetBSD: ip6_forward.c,v 1.4 1999/07/30 10:35:36 itojun Exp $ */
1999-07-04 01:24:45 +04:00
/*
* 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.
*/
#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 <netinet6/ip6.h>
#if !defined(__FreeBSD__) || __FreeBSD__ < 3
#include <netinet6/in6_pcb.h>
#endif
#include <netinet6/ip6_var.h>
#include <netinet6/icmp6.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;
{
register 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;
if (m->m_flags & (M_BCAST|M_MCAST) ||
in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) {
ip6stat.ip6s_cantforward++;
ip6stat.ip6s_badscope++;
#if !defined(__FreeBSD__) || __FreeBSD__ < 3
if (ip6_log_time + ip6_log_interval < time.tv_sec) {
ip6_log_time = time.tv_sec;
#else
if (ip6_log_time + ip6_log_interval < time_second) {
ip6_log_time = time_second;
#endif
log(LOG_DEBUG,
"cannot forward "
"from %s to %s nxt %d received on %s\n",
ip6_sprintf(&ip6->ip6_src), /* XXX meaningless */
ip6_sprintf(&ip6->ip6_dst),
ip6->ip6_nxt,
m->m_pkthdr.rcvif->if_xname);
}
m_freem(m);
return;
}
if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
icmp6_error(m, ICMP6_TIME_EXCEEDED,
ICMP6_TIME_EXCEED_TRANSIT, 0);
return;
}
ip6->ip6_hlim -= IPV6_HLIMDEC;
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 */
#ifdef __NetBSD__
rtalloc((struct route *)&ip6_forward_rt);
#else
rtalloc_ign((struct route *)&ip6_forward_rt,
RTF_PRCLONING);
#endif
}
if (ip6_forward_rt.ro_rt == 0) {
ip6stat.ip6s_noroute++;
icmp6_error(m, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_NOROUTE, 0);
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;
#ifdef __NetBSD__
rtalloc((struct route *)&ip6_forward_rt);
#else
rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
#endif
if (ip6_forward_rt.ro_rt == 0) {
ip6stat.ip6s_noroute++;
icmp6_error(m, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_NOROUTE, 0);
return;
}
}
rt = ip6_forward_rt.ro_rt;
if (m->m_pkthdr.len > rt->rt_ifp->if_mtu){
icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, rt->rt_ifp->if_mtu);
return;
}
if (rt->rt_flags & RTF_GATEWAY)
dst = (struct sockaddr_in6 *)rt->rt_gateway;
/*
* Save at most 528 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.
*/
mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
/*
* 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;
error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m,
(struct sockaddr *)dst,
ip6_forward_rt.ro_rt);
if (error)
ip6stat.ip6s_cantforward++;
else {
ip6stat.ip6s_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);
}