3 * This is the IP layer implementation for incoming and outgoing IP traffic.
9 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
10 * All rights reserved.
12 * Redistribution and use in source and binary forms, with or without modification,
13 * are permitted provided that the following conditions are met:
15 * 1. Redistributions of source code must retain the above copyright notice,
16 * this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright notice,
18 * this list of conditions and the following disclaimer in the documentation
19 * and/or other materials provided with the distribution.
20 * 3. The name of the author may not be used to endorse or promote products
21 * derived from this software without specific prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
24 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
26 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
27 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
28 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
31 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
34 * This file is part of the lwIP TCP/IP stack.
36 * Author: Adam Dunkels <adam@sics.se>
45 #include "lwip/ip_frag.h"
46 #include "lwip/inet.h"
47 #include "lwip/netif.h"
48 #include "lwip/icmp.h"
53 #include "lwip/stats.h"
55 #include "arch/perf.h"
57 #include "lwip/snmp.h"
59 # include "lwip/dhcp.h"
60 #endif /* LWIP_DHCP */
63 * Initializes the IP layer.
75 * Finds the appropriate network interface for a given IP address. It
76 * searches the list of network interfaces linearly. A match is found
77 * if the masked IP address of the network interface equals the masked
78 * IP address given to the function.
82 ip_route(struct ip_addr *dest)
86 /* iterate through netifs */
87 for(netif = netif_list; netif != NULL; netif = netif->next) {
88 /* network mask matches? */
89 if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
90 /* return netif on which to forward IP packet */
94 /* no matching netif found, use default netif */
100 * Forwards an IP packet. It finds an appropriate route for the
101 * packet, decrements the TTL value of the packet, adjusts the
102 * checksum and outputs the packet on the appropriate interface.
105 static struct netif *
106 ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
111 /* Find network interface where to forward this IP packet to. */
112 netif = ip_route((struct ip_addr *)&(iphdr->dest));
114 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for 0x%"X32_F" found\n",
116 snmp_inc_ipoutnoroutes();
117 return (struct netif *)NULL;
119 /* Do not forward packets onto the same network interface on which
122 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
123 snmp_inc_ipoutnoroutes();
124 return (struct netif *)NULL;
128 IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
129 /* send ICMP if TTL == 0 */
130 if (IPH_TTL(iphdr) == 0) {
131 snmp_inc_ipinhdrerrors();
132 /* Don't send ICMP messages in response to ICMP messages */
133 if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
134 icmp_time_exceeded(p, ICMP_TE_TTL);
136 return (struct netif *)NULL;
139 /* Incrementally update the IP checksum. */
140 if (IPH_CHKSUM(iphdr) >= htons(0xffff - 0x100)) {
141 IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100) + 1);
143 IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100));
146 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to 0x%"X32_F"\n",
150 IP_STATS_INC(ip.xmit);
151 snmp_inc_ipforwdatagrams();
153 PERF_STOP("ip_forward");
154 /* transmit pbuf on chosen interface */
155 netif->output(netif, p, (struct ip_addr *)&(iphdr->dest));
158 #endif /* IP_FORWARD */
161 * This function is called by the network interface device driver when
162 * an IP packet is received. The function does the basic checks of the
163 * IP header such as packet size being at least larger than the header
164 * size etc. If the packet was not destined for us, the packet is
165 * forwarded (using ip_forward). The IP checksum is always checked.
167 * Finally, the packet is sent to the upper layer protocol input function.
174 ip_input(struct pbuf *p, struct netif *inp) {
175 struct ip_hdr *iphdr;
179 IP_STATS_INC(ip.recv);
180 snmp_inc_ipinreceives();
182 /* identify the IP header */
184 if (IPH_V(iphdr) != 4) {
185 LWIP_DEBUGF(IP_DEBUG | 1, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
\r
188 IP_STATS_INC(ip.err);
189 IP_STATS_INC(ip.drop);
190 snmp_inc_ipinhdrerrors();
193 /* obtain IP header length in number of 32-bit words */
194 iphdrlen = IPH_HL(iphdr);
195 /* calculate IP header length in bytes */
198 /* header length exceeds first pbuf length? */
199 if (iphdrlen > p->len) {
200 LWIP_DEBUGF(IP_DEBUG | 2, ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet droppped.\n",
202 /* free (drop) packet pbufs */
204 IP_STATS_INC(ip.lenerr);
205 IP_STATS_INC(ip.drop);
206 snmp_inc_ipindiscards();
210 /* verify checksum */
211 #if CHECKSUM_CHECK_IP
212 if (inet_chksum(iphdr, iphdrlen) != 0) {
214 LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdrlen)));
217 IP_STATS_INC(ip.chkerr);
218 IP_STATS_INC(ip.drop);
219 snmp_inc_ipinhdrerrors();
224 /* Trim pbuf. This should have been done at the netif layer,
225 * but we'll do it anyway just to be sure that its done. */
226 pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));
228 /* match packet against an interface, i.e. is this packet for us? */
229 for (netif = netif_list; netif != NULL; netif = netif->next) {
231 LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
232 iphdr->dest.addr, netif->ip_addr.addr,
233 iphdr->dest.addr & netif->netmask.addr,
234 netif->ip_addr.addr & netif->netmask.addr,
235 iphdr->dest.addr & ~(netif->netmask.addr)));
237 /* interface is up and configured? */
238 if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr))))
240 /* unicast to this interface address? */
241 if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
242 /* or broadcast on this interface network address? */
243 ip_addr_isbroadcast(&(iphdr->dest), netif)) {
244 LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
245 netif->name[0], netif->name[1]));
246 /* break out of for loop */
252 /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
253 * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
254 * According to RFC 1542 section 3.1.1, referred by RFC 2131).
257 /* remote port is DHCP server? */
258 if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
259 LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
260 ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest)));
261 if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest) == DHCP_CLIENT_PORT) {
262 LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: DHCP packet accepted.\n"));
267 #endif /* LWIP_DHCP */
268 /* packet not for us? */
270 /* packet not for us, route or discard */
271 LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: packet not for us.\n"));
273 /* non-broadcast packet? */
274 if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
275 /* try to forward IP packet on (other) interfaces */
276 ip_forward(p, iphdr, inp);
279 #endif /* IP_FORWARD */
281 snmp_inc_ipinaddrerrors();
282 snmp_inc_ipindiscards();
287 /* packet consists of multiple fragments? */
288 if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
289 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
290 LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip_reass()\n",
291 ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
292 /* reassemble the packet*/
294 /* packet not fully reassembled yet? */
299 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
301 LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
302 ntohs(IPH_OFFSET(iphdr))));
303 IP_STATS_INC(ip.opterr);
304 IP_STATS_INC(ip.drop);
305 /* unsupported protocol feature */
306 snmp_inc_ipinunknownprotos();
308 #endif /* IP_REASSEMBLY */
311 #if IP_OPTIONS == 0 /* no support for IP options in the IP header? */
312 if (iphdrlen > IP_HLEN) {
313 LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS == 0).\n"));
315 IP_STATS_INC(ip.opterr);
316 IP_STATS_INC(ip.drop);
317 /* unsupported protocol feature */
318 snmp_inc_ipinunknownprotos();
321 #endif /* IP_OPTIONS == 0 */
323 /* send to upper layers */
324 LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
326 LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
329 /* raw input did not eat the packet? */
330 if (raw_input(p, inp) == 0) {
331 #endif /* LWIP_RAW */
333 switch (IPH_PROTO(iphdr)) {
336 case IP_PROTO_UDPLITE:
337 snmp_inc_ipindelivers();
340 #endif /* LWIP_UDP */
343 snmp_inc_ipindelivers();
346 #endif /* LWIP_TCP */
348 snmp_inc_ipindelivers();
352 /* send ICMP destination protocol unreachable unless is was a broadcast */
353 if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
354 !ip_addr_ismulticast(&(iphdr->dest))) {
356 icmp_dest_unreach(p, ICMP_DUR_PROTO);
360 LWIP_DEBUGF(IP_DEBUG | 2, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));
362 IP_STATS_INC(ip.proterr);
363 IP_STATS_INC(ip.drop);
364 snmp_inc_ipinunknownprotos();
373 * Sends an IP packet on a network interface. This function constructs
374 * the IP header and calculates the IP header checksum. If the source
375 * IP address is NULL, the IP address of the outgoing network
376 * interface is filled in as source address.
378 * @note ip_id: RFC791 "some host may be able to simply use
379 * unique identifiers independent of destination"
383 ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
385 u8_t proto, struct netif *netif)
387 struct ip_hdr *iphdr;
388 static u16_t ip_id = 0;
390 snmp_inc_ipoutrequests();
392 if (dest != IP_HDRINCL) {
393 if (pbuf_header(p, IP_HLEN)) {
394 LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: not enough room for IP header in pbuf\n"));
396 IP_STATS_INC(ip.err);
397 snmp_inc_ipoutdiscards();
403 IPH_TTL_SET(iphdr, ttl);
404 IPH_PROTO_SET(iphdr, proto);
406 ip_addr_set(&(iphdr->dest), dest);
408 IPH_VHLTOS_SET(iphdr, 4, IP_HLEN / 4, tos);
409 IPH_LEN_SET(iphdr, htons(p->tot_len));
410 IPH_OFFSET_SET(iphdr, htons(IP_DF));
411 IPH_ID_SET(iphdr, htons(ip_id));
414 if (ip_addr_isany(src)) {
415 ip_addr_set(&(iphdr->src), &(netif->ip_addr));
417 ip_addr_set(&(iphdr->src), src);
420 IPH_CHKSUM_SET(iphdr, 0);
422 IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
426 dest = &(iphdr->dest);
430 /* don't fragment if interface has mtu set to 0 [loopif] */
431 if (netif->mtu && (p->tot_len > netif->mtu))
432 return ip_frag(p,netif,dest);
435 IP_STATS_INC(ip.xmit);
437 LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
440 LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
442 return netif->output(netif, p, dest);
446 * Simple interface to ip_output_if. It finds the outgoing network
447 * interface and calls upon ip_output_if to do the actual work.
451 ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
452 u8_t ttl, u8_t tos, u8_t proto)
456 if ((netif = ip_route(dest)) == NULL) {
457 LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
459 IP_STATS_INC(ip.rterr);
460 snmp_inc_ipoutnoroutes();
464 return ip_output_if(p, src, dest, ttl, tos, proto, netif);
469 ip_debug_print(struct pbuf *p)
471 struct ip_hdr *iphdr = p->payload;
474 payload = (u8_t *)iphdr + IP_HLEN;
476 LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
477 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
478 LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" | 0x%02"X16_F" | %5"U16_F" | (v, hl, tos, len)\n",
482 ntohs(IPH_LEN(iphdr))));
483 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
484 LWIP_DEBUGF(IP_DEBUG, ("| %5"U16_F" |%"U16_F"%"U16_F"%"U16_F"| %4"U16_F" | (id, flags, offset)\n",
485 ntohs(IPH_ID(iphdr)),
486 ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
487 ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
488 ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
489 ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
490 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
491 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | 0x%04"X16_F" | (ttl, proto, chksum)\n",
494 ntohs(IPH_CHKSUM(iphdr))));
495 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
496 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (src)\n",
497 ip4_addr1(&iphdr->src),
498 ip4_addr2(&iphdr->src),
499 ip4_addr3(&iphdr->src),
500 ip4_addr4(&iphdr->src)));
501 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
502 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (dest)\n",
503 ip4_addr1(&iphdr->dest),
504 ip4_addr2(&iphdr->dest),
505 ip4_addr3(&iphdr->dest),
506 ip4_addr4(&iphdr->dest)));
507 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
509 #endif /* IP_DEBUG */