ip6_forward.c revision 1.3
1 /* $NetBSD: ip6_forward.c,v 1.3 1999/07/03 21:30:18 thorpej 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/in6_systm.h> 50 #include <netinet6/ip6.h> 51 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 52 #include <netinet6/in6_pcb.h> 53 #endif 54 #include <netinet6/ip6_var.h> 55 #include <netinet6/icmp6.h> 56 57 struct route_in6 ip6_forward_rt; 58 59 /* 60 * Forward a packet. If some error occurs return the sender 61 * an icmp packet. Note we can't always generate a meaningful 62 * icmp message because icmp doesn't have a large enough repertoire 63 * of codes and types. 64 * 65 * If not forwarding, just drop the packet. This could be confusing 66 * if ipforwarding was zero but some routing protocol was advancing 67 * us as a gateway to somewhere. However, we must let the routing 68 * protocol deal with that. 69 * 70 */ 71 72 void 73 ip6_forward(m, srcrt) 74 struct mbuf *m; 75 int srcrt; 76 { 77 register struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 78 register struct sockaddr_in6 *dst; 79 register struct rtentry *rt; 80 int error, type = 0, code = 0; 81 struct mbuf *mcopy; 82 83 if (m->m_flags & (M_BCAST|M_MCAST) || 84 in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) { 85 ip6stat.ip6s_cantforward++; 86 ip6stat.ip6s_badscope++; 87 #if !defined(__FreeBSD__) || __FreeBSD__ < 3 88 if (ip6_log_time + ip6_log_interval < time.tv_sec) { 89 ip6_log_time = time.tv_sec; 90 #else 91 if (ip6_log_time + ip6_log_interval < time_second) { 92 ip6_log_time = time_second; 93 #endif 94 log(LOG_DEBUG, 95 "cannot forward " 96 "from %s to %s nxt %d received on %s\n", 97 ip6_sprintf(&ip6->ip6_src), /* XXX meaningless */ 98 ip6_sprintf(&ip6->ip6_dst), 99 ip6->ip6_nxt, 100 m->m_pkthdr.rcvif->if_xname); 101 } 102 m_freem(m); 103 return; 104 } 105 106 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 107 icmp6_error(m, ICMP6_TIME_EXCEEDED, 108 ICMP6_TIME_EXCEED_TRANSIT, 0); 109 return; 110 } 111 ip6->ip6_hlim -= IPV6_HLIMDEC; 112 113 dst = &ip6_forward_rt.ro_dst; 114 if (!srcrt) { 115 /* 116 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 117 */ 118 if (ip6_forward_rt.ro_rt == 0 || 119 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 120 if (ip6_forward_rt.ro_rt) { 121 RTFREE(ip6_forward_rt.ro_rt); 122 ip6_forward_rt.ro_rt = 0; 123 } 124 /* this probably fails but give it a try again */ 125 #ifdef __NetBSD__ 126 rtalloc((struct route *)&ip6_forward_rt); 127 #else 128 rtalloc_ign((struct route *)&ip6_forward_rt, 129 RTF_PRCLONING); 130 #endif 131 } 132 133 if (ip6_forward_rt.ro_rt == 0) { 134 ip6stat.ip6s_noroute++; 135 icmp6_error(m, ICMP6_DST_UNREACH, 136 ICMP6_DST_UNREACH_NOROUTE, 0); 137 return; 138 } 139 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 140 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 141 if (ip6_forward_rt.ro_rt) { 142 RTFREE(ip6_forward_rt.ro_rt); 143 ip6_forward_rt.ro_rt = 0; 144 } 145 bzero(dst, sizeof(*dst)); 146 dst->sin6_len = sizeof(struct sockaddr_in6); 147 dst->sin6_family = AF_INET6; 148 dst->sin6_addr = ip6->ip6_dst; 149 150 #ifdef __NetBSD__ 151 rtalloc((struct route *)&ip6_forward_rt); 152 #else 153 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); 154 #endif 155 if (ip6_forward_rt.ro_rt == 0) { 156 ip6stat.ip6s_noroute++; 157 icmp6_error(m, ICMP6_DST_UNREACH, 158 ICMP6_DST_UNREACH_NOROUTE, 0); 159 return; 160 } 161 } 162 rt = ip6_forward_rt.ro_rt; 163 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu){ 164 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, rt->rt_ifp->if_mtu); 165 return; 166 } 167 168 if (rt->rt_flags & RTF_GATEWAY) 169 dst = (struct sockaddr_in6 *)rt->rt_gateway; 170 /* 171 * Save at most 528 bytes of the packet in case 172 * we need to generate an ICMP6 message to the src. 173 * Thanks to M_EXT, in most cases copy will not occur. 174 */ 175 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 176 177 /* 178 * If we are to forward the packet using the same interface 179 * as one we got the packet from, perhaps we should send a redirect 180 * to sender to shortcut a hop. 181 * Only send redirect if source is sending directly to us, 182 * and if packet was not source routed (or has any options). 183 * Also, don't send redirect if forwarding using a route 184 * modified by a redirect. 185 */ 186 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 187 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 188 type = ND_REDIRECT; 189 190 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 191 (struct sockaddr *)dst, 192 ip6_forward_rt.ro_rt); 193 if (error) 194 ip6stat.ip6s_cantforward++; 195 else { 196 ip6stat.ip6s_forward++; 197 if (type) 198 ip6stat.ip6s_redirectsent++; 199 else { 200 if (mcopy) 201 goto freecopy; 202 } 203 } 204 if (mcopy == NULL) 205 return; 206 207 switch (error) { 208 case 0: 209 #if 1 210 if (type == ND_REDIRECT) { 211 icmp6_redirect_output(mcopy, rt); 212 return; 213 } 214 #endif 215 goto freecopy; 216 217 case EMSGSIZE: 218 /* xxx MTU is constant in PPP? */ 219 goto freecopy; 220 221 case ENOBUFS: 222 /* Tell source to slow down like source quench in IP? */ 223 goto freecopy; 224 225 case ENETUNREACH: /* shouldn't happen, checked above */ 226 case EHOSTUNREACH: 227 case ENETDOWN: 228 case EHOSTDOWN: 229 default: 230 type = ICMP6_DST_UNREACH; 231 code = ICMP6_DST_UNREACH_ADDR; 232 break; 233 } 234 icmp6_error(mcopy, type, code, 0); 235 return; 236 237 freecopy: 238 m_freem(mcopy); 239 } 240
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