ip6_forward.c revision 1.2
1 /* 2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the project nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/malloc.h> 33 #include <sys/mbuf.h> 34 #include <sys/domain.h> 35 #include <sys/protosw.h> 36 #include <sys/socket.h> 37 #include <sys/errno.h> 38 #include <sys/time.h> 39 #include <sys/kernel.h> 40 #include <sys/syslog.h> 41 42 #include <net/if.h> 43 #include <net/route.h> 44 45 #include <netinet/in.h> 46 #include <netinet/in_var.h> 47 #include <netinet6/in6_systm.h> 48 #include <netinet6/ip6.h> 49 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 50 #include <netinet6/in6_pcb.h> 51 #endif 52 #include <netinet6/ip6_var.h> 53 #include <netinet6/icmp6.h> 54 55 struct route_in6 ip6_forward_rt; 56 57 /* 58 * Forward a packet. If some error occurs return the sender 59 * an icmp packet. Note we can't always generate a meaningful 60 * icmp message because icmp doesn't have a large enough repertoire 61 * of codes and types. 62 * 63 * If not forwarding, just drop the packet. This could be confusing 64 * if ipforwarding was zero but some routing protocol was advancing 65 * us as a gateway to somewhere. However, we must let the routing 66 * protocol deal with that. 67 * 68 */ 69 70 void 71 ip6_forward(m, srcrt) 72 struct mbuf *m; 73 int srcrt; 74 { 75 register struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 76 register struct sockaddr_in6 *dst; 77 register struct rtentry *rt; 78 int error, type = 0, code = 0; 79 struct mbuf *mcopy; 80 81 if (m->m_flags & (M_BCAST|M_MCAST) || 82 in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) { 83 ip6stat.ip6s_cantforward++; 84 ip6stat.ip6s_badscope++; 85 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 86 if (ip6_log_time + ip6_log_interval < time.tv_sec) { 87 ip6_log_time = time.tv_sec; 88 #else 89 if (ip6_log_time + ip6_log_interval < time_second) { 90 ip6_log_time = time_second; 91 #endif 92 log(LOG_DEBUG, 93 "cannot forward " 94 "from %s to %s nxt %d received on %s\n", 95 ip6_sprintf(&ip6->ip6_src), /* XXX meaningless */ 96 ip6_sprintf(&ip6->ip6_dst), 97 ip6->ip6_nxt, 98 m->m_pkthdr.rcvif->if_xname); 99 } 100 m_freem(m); 101 return; 102 } 103 104 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 105 icmp6_error(m, ICMP6_TIME_EXCEEDED, 106 ICMP6_TIME_EXCEED_TRANSIT, 0); 107 return; 108 } 109 ip6->ip6_hlim -= IPV6_HLIMDEC; 110 111 dst = &ip6_forward_rt.ro_dst; 112 if (!srcrt) { 113 /* 114 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 115 */ 116 if (ip6_forward_rt.ro_rt == 0 || 117 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 118 if (ip6_forward_rt.ro_rt) { 119 RTFREE(ip6_forward_rt.ro_rt); 120 ip6_forward_rt.ro_rt = 0; 121 } 122 /* this probably fails but give it a try again */ 123 #ifdef __NetBSD__ 124 rtalloc((struct route *)&ip6_forward_rt); 125 #else 126 rtalloc_ign((struct route *)&ip6_forward_rt, 127 RTF_PRCLONING); 128 #endif 129 } 130 131 if (ip6_forward_rt.ro_rt == 0) { 132 ip6stat.ip6s_noroute++; 133 icmp6_error(m, ICMP6_DST_UNREACH, 134 ICMP6_DST_UNREACH_NOROUTE, 0); 135 return; 136 } 137 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 138 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 139 if (ip6_forward_rt.ro_rt) { 140 RTFREE(ip6_forward_rt.ro_rt); 141 ip6_forward_rt.ro_rt = 0; 142 } 143 bzero(dst, sizeof(*dst)); 144 dst->sin6_len = sizeof(struct sockaddr_in6); 145 dst->sin6_family = AF_INET6; 146 dst->sin6_addr = ip6->ip6_dst; 147 148 #ifdef __NetBSD__ 149 rtalloc((struct route *)&ip6_forward_rt); 150 #else 151 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); 152 #endif 153 if (ip6_forward_rt.ro_rt == 0) { 154 ip6stat.ip6s_noroute++; 155 icmp6_error(m, ICMP6_DST_UNREACH, 156 ICMP6_DST_UNREACH_NOROUTE, 0); 157 return; 158 } 159 } 160 rt = ip6_forward_rt.ro_rt; 161 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu){ 162 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, rt->rt_ifp->if_mtu); 163 return; 164 } 165 166 if (rt->rt_flags & RTF_GATEWAY) 167 dst = (struct sockaddr_in6 *)rt->rt_gateway; 168 /* 169 * Save at most 528 bytes of the packet in case 170 * we need to generate an ICMP6 message to the src. 171 * Thanks to M_EXT, in most cases copy will not occur. 172 */ 173 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 174 175 /* 176 * If we are to forward the packet using the same interface 177 * as one we got the packet from, perhaps we should send a redirect 178 * to sender to shortcut a hop. 179 * Only send redirect if source is sending directly to us, 180 * and if packet was not source routed (or has any options). 181 * Also, don't send redirect if forwarding using a route 182 * modified by a redirect. 183 */ 184 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 185 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 186 type = ND_REDIRECT; 187 188 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 189 (struct sockaddr *)dst, 190 ip6_forward_rt.ro_rt); 191 if (error) 192 ip6stat.ip6s_cantforward++; 193 else { 194 ip6stat.ip6s_forward++; 195 if (type) 196 ip6stat.ip6s_redirectsent++; 197 else { 198 if (mcopy) 199 goto freecopy; 200 } 201 } 202 if (mcopy == NULL) 203 return; 204 205 switch (error) { 206 case 0: 207 #if 1 208 if (type == ND_REDIRECT) { 209 icmp6_redirect_output(mcopy, rt); 210 return; 211 } 212 #endif 213 goto freecopy; 214 215 case EMSGSIZE: 216 /* xxx MTU is constant in PPP? */ 217 goto freecopy; 218 219 case ENOBUFS: 220 /* Tell source to slow down like source quench in IP? */ 221 goto freecopy; 222 223 case ENETUNREACH: /* shouldn't happen, checked above */ 224 case EHOSTUNREACH: 225 case ENETDOWN: 226 case EHOSTDOWN: 227 default: 228 type = ICMP6_DST_UNREACH; 229 code = ICMP6_DST_UNREACH_ADDR; 230 break; 231 } 232 icmp6_error(mcopy, type, code, 0); 233 return; 234 235 freecopy: 236 m_freem(mcopy); 237 } 238
Indexes created Fri Sep 26 20:09:58 GMT 2025