ip6_forward.c revision 1.4
1 /* $NetBSD: ip6_forward.c,v 1.4 1999/07/30 10:35:36 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 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/malloc.h> 35 #include <sys/mbuf.h> 36 #include <sys/domain.h> 37 #include <sys/protosw.h> 38 #include <sys/socket.h> 39 #include <sys/errno.h> 40 #include <sys/time.h> 41 #include <sys/kernel.h> 42 #include <sys/syslog.h> 43 44 #include <net/if.h> 45 #include <net/route.h> 46 47 #include <netinet/in.h> 48 #include <netinet/in_var.h> 49 #include <netinet6/ip6.h> 50 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 51 #include <netinet6/in6_pcb.h> 52 #endif 53 #include <netinet6/ip6_var.h> 54 #include <netinet6/icmp6.h> 55 56 struct route_in6 ip6_forward_rt; 57 58 /* 59 * Forward a packet. If some error occurs return the sender 60 * an icmp packet. Note we can't always generate a meaningful 61 * icmp message because icmp doesn't have a large enough repertoire 62 * of codes and types. 63 * 64 * If not forwarding, just drop the packet. This could be confusing 65 * if ipforwarding was zero but some routing protocol was advancing 66 * us as a gateway to somewhere. However, we must let the routing 67 * protocol deal with that. 68 * 69 */ 70 71 void 72 ip6_forward(m, srcrt) 73 struct mbuf *m; 74 int srcrt; 75 { 76 register struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 77 register struct sockaddr_in6 *dst; 78 register struct rtentry *rt; 79 int error, type = 0, code = 0; 80 struct mbuf *mcopy; 81 82 if (m->m_flags & (M_BCAST|M_MCAST) || 83 in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) { 84 ip6stat.ip6s_cantforward++; 85 ip6stat.ip6s_badscope++; 86 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 87 if (ip6_log_time + ip6_log_interval < time.tv_sec) { 88 ip6_log_time = time.tv_sec; 89 #else 90 if (ip6_log_time + ip6_log_interval < time_second) { 91 ip6_log_time = time_second; 92 #endif 93 log(LOG_DEBUG, 94 "cannot forward " 95 "from %s to %s nxt %d received on %s\n", 96 ip6_sprintf(&ip6->ip6_src), /* XXX meaningless */ 97 ip6_sprintf(&ip6->ip6_dst), 98 ip6->ip6_nxt, 99 m->m_pkthdr.rcvif->if_xname); 100 } 101 m_freem(m); 102 return; 103 } 104 105 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 106 icmp6_error(m, ICMP6_TIME_EXCEEDED, 107 ICMP6_TIME_EXCEED_TRANSIT, 0); 108 return; 109 } 110 ip6->ip6_hlim -= IPV6_HLIMDEC; 111 112 dst = &ip6_forward_rt.ro_dst; 113 if (!srcrt) { 114 /* 115 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 116 */ 117 if (ip6_forward_rt.ro_rt == 0 || 118 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 119 if (ip6_forward_rt.ro_rt) { 120 RTFREE(ip6_forward_rt.ro_rt); 121 ip6_forward_rt.ro_rt = 0; 122 } 123 /* this probably fails but give it a try again */ 124 #ifdef __NetBSD__ 125 rtalloc((struct route *)&ip6_forward_rt); 126 #else 127 rtalloc_ign((struct route *)&ip6_forward_rt, 128 RTF_PRCLONING); 129 #endif 130 } 131 132 if (ip6_forward_rt.ro_rt == 0) { 133 ip6stat.ip6s_noroute++; 134 icmp6_error(m, ICMP6_DST_UNREACH, 135 ICMP6_DST_UNREACH_NOROUTE, 0); 136 return; 137 } 138 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 139 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 140 if (ip6_forward_rt.ro_rt) { 141 RTFREE(ip6_forward_rt.ro_rt); 142 ip6_forward_rt.ro_rt = 0; 143 } 144 bzero(dst, sizeof(*dst)); 145 dst->sin6_len = sizeof(struct sockaddr_in6); 146 dst->sin6_family = AF_INET6; 147 dst->sin6_addr = ip6->ip6_dst; 148 149 #ifdef __NetBSD__ 150 rtalloc((struct route *)&ip6_forward_rt); 151 #else 152 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); 153 #endif 154 if (ip6_forward_rt.ro_rt == 0) { 155 ip6stat.ip6s_noroute++; 156 icmp6_error(m, ICMP6_DST_UNREACH, 157 ICMP6_DST_UNREACH_NOROUTE, 0); 158 return; 159 } 160 } 161 rt = ip6_forward_rt.ro_rt; 162 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu){ 163 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, rt->rt_ifp->if_mtu); 164 return; 165 } 166 167 if (rt->rt_flags & RTF_GATEWAY) 168 dst = (struct sockaddr_in6 *)rt->rt_gateway; 169 /* 170 * Save at most 528 bytes of the packet in case 171 * we need to generate an ICMP6 message to the src. 172 * Thanks to M_EXT, in most cases copy will not occur. 173 */ 174 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 175 176 /* 177 * If we are to forward the packet using the same interface 178 * as one we got the packet from, perhaps we should send a redirect 179 * to sender to shortcut a hop. 180 * Only send redirect if source is sending directly to us, 181 * and if packet was not source routed (or has any options). 182 * Also, don't send redirect if forwarding using a route 183 * modified by a redirect. 184 */ 185 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 186 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 187 type = ND_REDIRECT; 188 189 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 190 (struct sockaddr *)dst, 191 ip6_forward_rt.ro_rt); 192 if (error) 193 ip6stat.ip6s_cantforward++; 194 else { 195 ip6stat.ip6s_forward++; 196 if (type) 197 ip6stat.ip6s_redirectsent++; 198 else { 199 if (mcopy) 200 goto freecopy; 201 } 202 } 203 if (mcopy == NULL) 204 return; 205 206 switch (error) { 207 case 0: 208 #if 1 209 if (type == ND_REDIRECT) { 210 icmp6_redirect_output(mcopy, rt); 211 return; 212 } 213 #endif 214 goto freecopy; 215 216 case EMSGSIZE: 217 /* xxx MTU is constant in PPP? */ 218 goto freecopy; 219 220 case ENOBUFS: 221 /* Tell source to slow down like source quench in IP? */ 222 goto freecopy; 223 224 case ENETUNREACH: /* shouldn't happen, checked above */ 225 case EHOSTUNREACH: 226 case ENETDOWN: 227 case EHOSTDOWN: 228 default: 229 type = ICMP6_DST_UNREACH; 230 code = ICMP6_DST_UNREACH_ADDR; 231 break; 232 } 233 icmp6_error(mcopy, type, code, 0); 234 return; 235 236 freecopy: 237 m_freem(mcopy); 238 } 239
Indexes created Wed Oct 15 03:09:54 GMT 2025