1 /**
2 * @file
3 * This is the IPv4 layer implementation for incoming and outgoing IP traffic.
4 *
5 * @see ip_frag.c
6 *
7 */
8
9 /*
10 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without modification,
14 * are permitted provided that the following conditions are met:
15 *
16 * 1. Redistributions of source code must retain the above copyright notice,
17 * this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright notice,
19 * this list of conditions and the following disclaimer in the documentation
20 * and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
25 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
27 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
28 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
29 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
32 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33 * OF SUCH DAMAGE.
34 *
35 * This file is part of the lwIP TCP/IP stack.
36 *
37 * Author: Adam Dunkels <adam@sics.se>
38 *
39 */
40
41 #include "lwip/opt.h"
42 #include "lwip/ip.h"
43 #include "lwip/def.h"
44 #include "lwip/mem.h"
45 #include "lwip/ip_frag.h"
46 #include "lwip/inet_chksum.h"
47 #include "lwip/netif.h"
48 #include "lwip/icmp.h"
49 #include "lwip/igmp.h"
50 #include "lwip/raw.h"
51 #include "lwip/udp.h"
52 #include "lwip/tcp_impl.h"
53 #include "lwip/snmp.h"
54 #include "lwip/dhcp.h"
55 #include "lwip/autoip.h"
56 #include "lwip/stats.h"
57 #include "arch/perf.h"
58
59 #include <string.h>
60
61 /** Set this to 0 in the rare case of wanting to call an extra function to
62 * generate the IP checksum (in contrast to calculating it on-the-fly). */
63 #ifndef LWIP_INLINE_IP_CHKSUM
64 #define LWIP_INLINE_IP_CHKSUM 1
65 #endif
66 #if LWIP_INLINE_IP_CHKSUM && CHECKSUM_GEN_IP
67 #define CHECKSUM_GEN_IP_INLINE 1
68 #else
69 #define CHECKSUM_GEN_IP_INLINE 0
70 #endif
71
72 #if LWIP_DHCP || defined(LWIP_IP_ACCEPT_UDP_PORT)
73 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 1
74
75 /** Some defines for DHCP to let link-layer-addressed packets through while the
76 * netif is down.
77 * To use this in your own application/protocol, define LWIP_IP_ACCEPT_UDP_PORT
78 * to return 1 if the port is accepted and 0 if the port is not accepted.
79 */
80 #if LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT)
81 /* accept DHCP client port and custom port */
82 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (((port) == PP_NTOHS(DHCP_CLIENT_PORT)) \
83 || (LWIP_IP_ACCEPT_UDP_PORT(port)))
84 #elif defined(LWIP_IP_ACCEPT_UDP_PORT) /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
85 /* accept custom port only */
86 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (LWIP_IP_ACCEPT_UDP_PORT(port))
87 #else /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
88 /* accept DHCP client port only */
89 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) ((port) == PP_NTOHS(DHCP_CLIENT_PORT))
90 #endif /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
91
92 #else /* LWIP_DHCP */
93 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 0
94 #endif /* LWIP_DHCP */
95
96 /**
97 * The interface that provided the packet for the current callback
98 * invocation.
99 */
100 struct netif *current_netif;
101
102 /**
103 * Header of the input packet currently being processed.
104 */
105 const struct ip_hdr *current_header;
106 /** Source IP address of current_header */
107 ip_addr_t current_iphdr_src;
108 /** Destination IP address of current_header */
109 ip_addr_t current_iphdr_dest;
110
111 /** The IP header ID of the next outgoing IP packet */
112 static u16_t ip_id;
113
114 /**
115 * Finds the appropriate network interface for a given IP address. It
116 * searches the list of network interfaces linearly. A match is found
117 * if the masked IP address of the network interface equals the masked
118 * IP address given to the function.
119 *
120 * @param dest the destination IP address for which to find the route
121 * @return the netif on which to send to reach dest
122 */
123 struct netif *
ip_route(ip_addr_t * dest)124 ip_route(ip_addr_t *dest)
125 {
126 struct netif *netif;
127
128 #ifdef LWIP_HOOK_IP4_ROUTE
129 netif = LWIP_HOOK_IP4_ROUTE(dest);
130 if (netif != NULL) {
131 return netif;
132 }
133 #endif
134
135 /* iterate through netifs */
136 for (netif = netif_list; netif != NULL; netif = netif->next) {
137 /* network mask matches? */
138 if (netif_is_up(netif)) {
139 if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
140 /* return netif on which to forward IP packet */
141 return netif;
142 }
143 }
144 }
145 if ((netif_default == NULL) || (!netif_is_up(netif_default))) {
146 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_route: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
147 ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
148 IP_STATS_INC(ip.rterr);
149 snmp_inc_ipoutnoroutes();
150 return NULL;
151 }
152 /* no matching netif found, use default netif */
153 return netif_default;
154 }
155
156 #if IP_FORWARD
157 /**
158 * Determine whether an IP address is in a reserved set of addresses
159 * that may not be forwarded, or whether datagrams to that destination
160 * may be forwarded.
161 * @param p the packet to forward
162 * @param dest the destination IP address
163 * @return 1: can forward 0: discard
164 */
165 static int
ip_canforward(struct pbuf * p)166 ip_canforward(struct pbuf *p)
167 {
168 u32_t addr = ip4_addr_get_u32(ip_current_dest_addr());
169
170 if (p->flags & PBUF_FLAG_LLBCAST) {
171 /* don't route link-layer broadcasts */
172 return 0;
173 }
174 if ((p->flags & PBUF_FLAG_LLMCAST) && !IP_MULTICAST(addr)) {
175 /* don't route link-layer multicasts unless the destination address is an IP
176 multicast address */
177 return 0;
178 }
179 if (IP_EXPERIMENTAL(addr)) {
180 return 0;
181 }
182 if (IP_CLASSA(addr)) {
183 u32_t net = addr & IP_CLASSA_NET;
184 if ((net == 0) || (net == (IP_LOOPBACKNET << IP_CLASSA_NSHIFT))) {
185 /* don't route loopback packets */
186 return 0;
187 }
188 }
189 return 1;
190 }
191
192 /**
193 * Forwards an IP packet. It finds an appropriate route for the
194 * packet, decrements the TTL value of the packet, adjusts the
195 * checksum and outputs the packet on the appropriate interface.
196 *
197 * @param p the packet to forward (p->payload points to IP header)
198 * @param iphdr the IP header of the input packet
199 * @param inp the netif on which this packet was received
200 */
201 static void
ip_forward(struct pbuf * p,struct ip_hdr * iphdr,struct netif * inp)202 ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
203 {
204 struct netif *netif;
205
206 PERF_START;
207
208 if (!ip_canforward(p)) {
209 goto return_noroute;
210 }
211
212 /* RFC3927 2.7: do not forward link-local addresses */
213 if (ip_addr_islinklocal(¤t_iphdr_dest)) {
214 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
215 ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest),
216 ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest)));
217 goto return_noroute;
218 }
219
220 /* Find network interface where to forward this IP packet to. */
221 netif = ip_route(¤t_iphdr_dest);
222 if (netif == NULL) {
223 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n",
224 ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest),
225 ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest)));
226 /* @todo: send ICMP_DUR_NET? */
227 goto return_noroute;
228 }
229 #if !IP_FORWARD_ALLOW_TX_ON_RX_NETIF
230 /* Do not forward packets onto the same network interface on which
231 * they arrived. */
232 if (netif == inp) {
233 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
234 goto return_noroute;
235 }
236 #endif /* IP_FORWARD_ALLOW_TX_ON_RX_NETIF */
237
238 /* decrement TTL */
239 IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
240 /* send ICMP if TTL == 0 */
241 if (IPH_TTL(iphdr) == 0) {
242 snmp_inc_ipinhdrerrors();
243 #if LWIP_ICMP
244 /* Don't send ICMP messages in response to ICMP messages */
245 if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
246 icmp_time_exceeded(p, ICMP_TE_TTL);
247 }
248 #endif /* LWIP_ICMP */
249 return;
250 }
251
252 /* Incrementally update the IP checksum. */
253 if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffffU - 0x100)) {
254 IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1);
255 } else {
256 IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100));
257 }
258
259 LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
260 ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest),
261 ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest)));
262
263 IP_STATS_INC(ip.fw);
264 IP_STATS_INC(ip.xmit);
265 snmp_inc_ipforwdatagrams();
266
267 PERF_STOP("ip_forward");
268 /* don't fragment if interface has mtu set to 0 [loopif] */
269 if (netif->mtu && (p->tot_len > netif->mtu)) {
270 if ((IPH_OFFSET(iphdr) & PP_NTOHS(IP_DF)) == 0) {
271 #if IP_FRAG
272 ip_frag(p, netif, ip_current_dest_addr());
273 #else /* IP_FRAG */
274 /* @todo: send ICMP Destination Unreacheable code 13 "Communication administratively prohibited"? */
275 #endif /* IP_FRAG */
276 } else {
277 /* send ICMP Destination Unreacheable code 4: "Fragmentation Needed and DF Set" */
278 icmp_dest_unreach(p, ICMP_DUR_FRAG);
279 }
280 return;
281 }
282 /* transmit pbuf on chosen interface */
283 netif->output(netif, p, ¤t_iphdr_dest);
284 return;
285 return_noroute:
286 snmp_inc_ipoutnoroutes();
287 }
288 #endif /* IP_FORWARD */
289
290 /**
291 * This function is called by the network interface device driver when
292 * an IP packet is received. The function does the basic checks of the
293 * IP header such as packet size being at least larger than the header
294 * size etc. If the packet was not destined for us, the packet is
295 * forwarded (using ip_forward). The IP checksum is always checked.
296 *
297 * Finally, the packet is sent to the upper layer protocol input function.
298 *
299 * @param p the received IP packet (p->payload points to IP header)
300 * @param inp the netif on which this packet was received
301 * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
302 * processed, but currently always returns ERR_OK)
303 */
304 err_t
ip_input(struct pbuf * p,struct netif * inp)305 ip_input(struct pbuf *p, struct netif *inp)
306 {
307 struct ip_hdr *iphdr;
308 struct netif *netif;
309 u16_t iphdr_hlen;
310 u16_t iphdr_len;
311 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
312 int check_ip_src=1;
313 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
314
315 IP_STATS_INC(ip.recv);
316 snmp_inc_ipinreceives();
317
318 /* identify the IP header */
319 iphdr = (struct ip_hdr *)p->payload;
320 if (IPH_V(iphdr) != 4) {
321 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
322 ip_debug_print(p);
323 pbuf_free(p);
324 IP_STATS_INC(ip.err);
325 IP_STATS_INC(ip.drop);
326 snmp_inc_ipinhdrerrors();
327 return ERR_OK;
328 }
329
330 #ifdef LWIP_HOOK_IP4_INPUT
331 if (LWIP_HOOK_IP4_INPUT(p, inp)) {
332 /* the packet has been eaten */
333 return ERR_OK;
334 }
335 #endif
336
337 /* obtain IP header length in number of 32-bit words */
338 iphdr_hlen = IPH_HL(iphdr);
339 /* calculate IP header length in bytes */
340 iphdr_hlen *= 4;
341 /* obtain ip length in bytes */
342 iphdr_len = ntohs(IPH_LEN(iphdr));
343
344 /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
345 if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len)) {
346 if (iphdr_hlen > p->len) {
347 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
348 ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
349 iphdr_hlen, p->len));
350 }
351 if (iphdr_len > p->tot_len) {
352 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
353 ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), IP packet dropped.\n",
354 iphdr_len, p->tot_len));
355 }
356 /* free (drop) packet pbufs */
357 pbuf_free(p);
358 IP_STATS_INC(ip.lenerr);
359 IP_STATS_INC(ip.drop);
360 snmp_inc_ipindiscards();
361 return ERR_OK;
362 }
363
364 /* verify checksum */
365 #if CHECKSUM_CHECK_IP
366 if (inet_chksum(iphdr, iphdr_hlen) != 0) {
367
368 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
369 ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
370 ip_debug_print(p);
371 pbuf_free(p);
372 IP_STATS_INC(ip.chkerr);
373 IP_STATS_INC(ip.drop);
374 snmp_inc_ipinhdrerrors();
375 return ERR_OK;
376 }
377 #endif
378
379 /* Trim pbuf. This should have been done at the netif layer,
380 * but we'll do it anyway just to be sure that its done. */
381 pbuf_realloc(p, iphdr_len);
382
383 /* copy IP addresses to aligned ip_addr_t */
384 ip_addr_copy(current_iphdr_dest, iphdr->dest);
385 ip_addr_copy(current_iphdr_src, iphdr->src);
386
387 /* match packet against an interface, i.e. is this packet for us? */
388 #if LWIP_IGMP
389 if (ip_addr_ismulticast(¤t_iphdr_dest)) {
390 if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, ¤t_iphdr_dest))) {
391 netif = inp;
392 } else {
393 netif = NULL;
394 }
395 } else
396 #endif /* LWIP_IGMP */
397 {
398 /* start trying with inp. if that's not acceptable, start walking the
399 list of configured netifs.
400 'first' is used as a boolean to mark whether we started walking the list */
401 int first = 1;
402 netif = inp;
403 do {
404 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",
405 ip4_addr_get_u32(&iphdr->dest), ip4_addr_get_u32(&netif->ip_addr),
406 ip4_addr_get_u32(&iphdr->dest) & ip4_addr_get_u32(&netif->netmask),
407 ip4_addr_get_u32(&netif->ip_addr) & ip4_addr_get_u32(&netif->netmask),
408 ip4_addr_get_u32(&iphdr->dest) & ~ip4_addr_get_u32(&netif->netmask)));
409
410 /* interface is up and configured? */
411 if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
412 /* unicast to this interface address? */
413 if (ip_addr_cmp(¤t_iphdr_dest, &(netif->ip_addr)) ||
414 /* or broadcast on this interface network address? */
415 ip_addr_isbroadcast(¤t_iphdr_dest, netif)) {
416 LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
417 netif->name[0], netif->name[1]));
418 /* break out of for loop */
419 break;
420 }
421 #if LWIP_AUTOIP
422 /* connections to link-local addresses must persist after changing
423 the netif's address (RFC3927 ch. 1.9) */
424 if ((netif->autoip != NULL) &&
425 ip_addr_cmp(¤t_iphdr_dest, &(netif->autoip->llipaddr))) {
426 LWIP_DEBUGF(IP_DEBUG, ("ip_input: LLA packet accepted on interface %c%c\n",
427 netif->name[0], netif->name[1]));
428 /* break out of for loop */
429 break;
430 }
431 #endif /* LWIP_AUTOIP */
432 }
433 if (first) {
434 first = 0;
435 netif = netif_list;
436 } else {
437 netif = netif->next;
438 }
439 if (netif == inp) {
440 netif = netif->next;
441 }
442 } while(netif != NULL);
443 }
444
445 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
446 /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
447 * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
448 * According to RFC 1542 section 3.1.1, referred by RFC 2131).
449 *
450 * If you want to accept private broadcast communication while a netif is down,
451 * define LWIP_IP_ACCEPT_UDP_PORT(dst_port), e.g.:
452 *
453 * #define LWIP_IP_ACCEPT_UDP_PORT(dst_port) ((dst_port) == PP_NTOHS(12345))
454 */
455 if (netif == NULL) {
456 /* remote port is DHCP server? */
457 if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
458 struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen);
459 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
460 ntohs(udphdr->dest)));
461 if (IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(udphdr->dest)) {
462 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: DHCP packet accepted.\n"));
463 netif = inp;
464 check_ip_src = 0;
465 }
466 }
467 }
468 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
469
470 /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
471 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
472 /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
473 if (check_ip_src && (current_iphdr_src.addr != IPADDR_ANY))
474 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
475 { if ((ip_addr_isbroadcast(¤t_iphdr_src, inp)) ||
476 (ip_addr_ismulticast(¤t_iphdr_src))) {
477 /* packet source is not valid */
478 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip_input: packet source is not valid.\n"));
479 /* free (drop) packet pbufs */
480 pbuf_free(p);
481 IP_STATS_INC(ip.drop);
482 snmp_inc_ipinaddrerrors();
483 snmp_inc_ipindiscards();
484 return ERR_OK;
485 }
486 }
487
488 /* packet not for us? */
489 if (netif == NULL) {
490 /* packet not for us, route or discard */
491 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: packet not for us.\n"));
492 #if IP_FORWARD
493 /* non-broadcast packet? */
494 if (!ip_addr_isbroadcast(¤t_iphdr_dest, inp)) {
495 /* try to forward IP packet on (other) interfaces */
496 ip_forward(p, iphdr, inp);
497 } else
498 #endif /* IP_FORWARD */
499 {
500 snmp_inc_ipinaddrerrors();
501 snmp_inc_ipindiscards();
502 }
503 pbuf_free(p);
504 return ERR_OK;
505 }
506 /* packet consists of multiple fragments? */
507 if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
508 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
509 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",
510 ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
511 /* reassemble the packet*/
512 p = ip_reass(p);
513 /* packet not fully reassembled yet? */
514 if (p == NULL) {
515 return ERR_OK;
516 }
517 iphdr = (struct ip_hdr *)p->payload;
518 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
519 pbuf_free(p);
520 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
521 ntohs(IPH_OFFSET(iphdr))));
522 IP_STATS_INC(ip.opterr);
523 IP_STATS_INC(ip.drop);
524 /* unsupported protocol feature */
525 snmp_inc_ipinunknownprotos();
526 return ERR_OK;
527 #endif /* IP_REASSEMBLY */
528 }
529
530 #if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
531
532 #if LWIP_IGMP
533 /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
534 if((iphdr_hlen > IP_HLEN) && (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
535 #else
536 if (iphdr_hlen > IP_HLEN) {
537 #endif /* LWIP_IGMP */
538 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
539 pbuf_free(p);
540 IP_STATS_INC(ip.opterr);
541 IP_STATS_INC(ip.drop);
542 /* unsupported protocol feature */
543 snmp_inc_ipinunknownprotos();
544 return ERR_OK;
545 }
546 #endif /* IP_OPTIONS_ALLOWED == 0 */
547
548 /* send to upper layers */
549 LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
550 ip_debug_print(p);
551 LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
552
553 current_netif = inp;
554 current_header = iphdr;
555
556 #if LWIP_RAW
557 /* raw input did not eat the packet? */
558 if (raw_input(p, inp) == 0)
559 #endif /* LWIP_RAW */
560 {
561 switch (IPH_PROTO(iphdr)) {
562 #if LWIP_UDP
563 case IP_PROTO_UDP:
564 #if LWIP_UDPLITE
565 case IP_PROTO_UDPLITE:
566 #endif /* LWIP_UDPLITE */
567 snmp_inc_ipindelivers();
568 udp_input(p, inp);
569 break;
570 #endif /* LWIP_UDP */
571 #if LWIP_TCP
572 case IP_PROTO_TCP:
573 snmp_inc_ipindelivers();
574 tcp_input(p, inp);
575 break;
576 #endif /* LWIP_TCP */
577 #if LWIP_ICMP
578 case IP_PROTO_ICMP:
579 snmp_inc_ipindelivers();
580 icmp_input(p, inp);
581 break;
582 #endif /* LWIP_ICMP */
583 #if LWIP_IGMP
584 case IP_PROTO_IGMP:
585 igmp_input(p, inp, ¤t_iphdr_dest);
586 break;
587 #endif /* LWIP_IGMP */
588 default:
589 #if LWIP_ICMP
590 /* send ICMP destination protocol unreachable unless is was a broadcast */
591 if (!ip_addr_isbroadcast(¤t_iphdr_dest, inp) &&
592 !ip_addr_ismulticast(¤t_iphdr_dest)) {
593 p->payload = iphdr;
594 icmp_dest_unreach(p, ICMP_DUR_PROTO);
595 }
596 #endif /* LWIP_ICMP */
597 pbuf_free(p);
598
599 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));
600
601 IP_STATS_INC(ip.proterr);
602 IP_STATS_INC(ip.drop);
603 snmp_inc_ipinunknownprotos();
604 }
605 }
606
607 current_netif = NULL;
608 current_header = NULL;
609 ip_addr_set_any(¤t_iphdr_src);
610 ip_addr_set_any(¤t_iphdr_dest);
611
612 return ERR_OK;
613 }
614
615 /**
616 * Sends an IP packet on a network interface. This function constructs
617 * the IP header and calculates the IP header checksum. If the source
618 * IP address is NULL, the IP address of the outgoing network
619 * interface is filled in as source address.
620 * If the destination IP address is IP_HDRINCL, p is assumed to already
621 * include an IP header and p->payload points to it instead of the data.
622 *
623 * @param p the packet to send (p->payload points to the data, e.g. next
624 protocol header; if dest == IP_HDRINCL, p already includes an IP
625 header and p->payload points to that IP header)
626 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
627 * IP address of the netif used to send is used as source address)
628 * @param dest the destination IP address to send the packet to
629 * @param ttl the TTL value to be set in the IP header
630 * @param tos the TOS value to be set in the IP header
631 * @param proto the PROTOCOL to be set in the IP header
632 * @param netif the netif on which to send this packet
633 * @return ERR_OK if the packet was sent OK
634 * ERR_BUF if p doesn't have enough space for IP/LINK headers
635 * returns errors returned by netif->output
636 *
637 * @note ip_id: RFC791 "some host may be able to simply use
638 * unique identifiers independent of destination"
639 */
640 err_t
641 ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
642 u8_t ttl, u8_t tos,
643 u8_t proto, struct netif *netif)
644 {
645 #if IP_OPTIONS_SEND
646 return ip_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
647 }
648
649 /**
650 * Same as ip_output_if() but with the possibility to include IP options:
651 *
652 * @ param ip_options pointer to the IP options, copied into the IP header
653 * @ param optlen length of ip_options
654 */
655 err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
656 u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
657 u16_t optlen)
658 {
659 #endif /* IP_OPTIONS_SEND */
660 struct ip_hdr *iphdr;
661 ip_addr_t dest_addr;
662 #if CHECKSUM_GEN_IP_INLINE
663 u32_t chk_sum = 0;
664 #endif /* CHECKSUM_GEN_IP_INLINE */
665
666 /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
667 gets altered as the packet is passed down the stack */
668 LWIP_ASSERT("p->ref == 1", p->ref == 1);
669
670 snmp_inc_ipoutrequests();
671
672 /* Should the IP header be generated or is it already included in p? */
673 if (dest != IP_HDRINCL) {
674 u16_t ip_hlen = IP_HLEN;
675 #if IP_OPTIONS_SEND
676 u16_t optlen_aligned = 0;
677 if (optlen != 0) {
678 #if CHECKSUM_GEN_IP_INLINE
679 int i;
680 #endif /* CHECKSUM_GEN_IP_INLINE */
681 /* round up to a multiple of 4 */
682 optlen_aligned = ((optlen + 3) & ~3);
683 ip_hlen += optlen_aligned;
684 /* First write in the IP options */
685 if (pbuf_header(p, optlen_aligned)) {
686 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output_if_opt: not enough room for IP options in pbuf\n"));
687 IP_STATS_INC(ip.err);
688 snmp_inc_ipoutdiscards();
689 return ERR_BUF;
690 }
691 MEMCPY(p->payload, ip_options, optlen);
692 if (optlen < optlen_aligned) {
693 /* zero the remaining bytes */
694 memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
695 }
696 #if CHECKSUM_GEN_IP_INLINE
697 for (i = 0; i < optlen_aligned/2; i++) {
698 chk_sum += ((u16_t*)p->payload)[i];
699 }
700 #endif /* CHECKSUM_GEN_IP_INLINE */
701 }
702 #endif /* IP_OPTIONS_SEND */
703 /* generate IP header */
704 if (pbuf_header(p, IP_HLEN)) {
705 LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output: not enough room for IP header in pbuf\n"));
706
707 IP_STATS_INC(ip.err);
708 snmp_inc_ipoutdiscards();
709 return ERR_BUF;
710 }
711
712 iphdr = (struct ip_hdr *)p->payload;
713 LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
714 (p->len >= sizeof(struct ip_hdr)));
715
716 IPH_TTL_SET(iphdr, ttl);
717 IPH_PROTO_SET(iphdr, proto);
718 #if CHECKSUM_GEN_IP_INLINE
719 chk_sum += LWIP_MAKE_U16(proto, ttl);
720 #endif /* CHECKSUM_GEN_IP_INLINE */
721
722 /* dest cannot be NULL here */
723 ip_addr_copy(iphdr->dest, *dest);
724 #if CHECKSUM_GEN_IP_INLINE
725 chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
726 chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
727 #endif /* CHECKSUM_GEN_IP_INLINE */
728
729 IPH_VHL_SET(iphdr, 4, ip_hlen / 4);
730 IPH_TOS_SET(iphdr, tos);
731 #if CHECKSUM_GEN_IP_INLINE
732 chk_sum += LWIP_MAKE_U16(tos, iphdr->_v_hl);
733 #endif /* CHECKSUM_GEN_IP_INLINE */
734 IPH_LEN_SET(iphdr, htons(p->tot_len));
735 #if CHECKSUM_GEN_IP_INLINE
736 chk_sum += iphdr->_len;
737 #endif /* CHECKSUM_GEN_IP_INLINE */
738 IPH_OFFSET_SET(iphdr, 0);
739 IPH_ID_SET(iphdr, htons(ip_id));
740 #if CHECKSUM_GEN_IP_INLINE
741 chk_sum += iphdr->_id;
742 #endif /* CHECKSUM_GEN_IP_INLINE */
743 ++ip_id;
744
745 if (ip_addr_isany(src)) {
746 ip_addr_copy(iphdr->src, netif->ip_addr);
747 } else {
748 /* src cannot be NULL here */
749 ip_addr_copy(iphdr->src, *src);
750 }
751
752 #if CHECKSUM_GEN_IP_INLINE
753 chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
754 chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
755 chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
756 chk_sum = (chk_sum >> 16) + chk_sum;
757 chk_sum = ~chk_sum;
758 iphdr->_chksum = chk_sum; /* network order */
759 #else /* CHECKSUM_GEN_IP_INLINE */
760 IPH_CHKSUM_SET(iphdr, 0);
761 #if CHECKSUM_GEN_IP
762 IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
763 #endif
764 #endif /* CHECKSUM_GEN_IP_INLINE */
765 } else {
766 /* IP header already included in p */
767 iphdr = (struct ip_hdr *)p->payload;
768 ip_addr_copy(dest_addr, iphdr->dest);
769 dest = &dest_addr;
770 }
771
772 IP_STATS_INC(ip.xmit);
773
774 LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
775 ip_debug_print(p);
776
777 #if ENABLE_LOOPBACK
778 if (ip_addr_cmp(dest, &netif->ip_addr)) {
779 /* Packet to self, enqueue it for loopback */
780 LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
781 return netif_loop_output(netif, p, dest);
782 }
783 #if LWIP_IGMP
784 if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
785 netif_loop_output(netif, p, dest);
786 }
787 #endif /* LWIP_IGMP */
788 #endif /* ENABLE_LOOPBACK */
789 #if IP_FRAG
790 /* don't fragment if interface has mtu set to 0 [loopif] */
791 if (netif->mtu && (p->tot_len > netif->mtu)) {
792 return ip_frag(p, netif, dest);
793 }
794 #endif /* IP_FRAG */
795
796 LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
797 return netif->output(netif, p, dest);
798 }
799
800 /**
801 * Simple interface to ip_output_if. It finds the outgoing network
802 * interface and calls upon ip_output_if to do the actual work.
803 *
804 * @param p the packet to send (p->payload points to the data, e.g. next
805 protocol header; if dest == IP_HDRINCL, p already includes an IP
806 header and p->payload points to that IP header)
807 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
808 * IP address of the netif used to send is used as source address)
809 * @param dest the destination IP address to send the packet to
810 * @param ttl the TTL value to be set in the IP header
811 * @param tos the TOS value to be set in the IP header
812 * @param proto the PROTOCOL to be set in the IP header
813 *
814 * @return ERR_RTE if no route is found
815 * see ip_output_if() for more return values
816 */
817 err_t
818 ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
819 u8_t ttl, u8_t tos, u8_t proto)
820 {
821 struct netif *netif;
822
823 /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
824 gets altered as the packet is passed down the stack */
825 LWIP_ASSERT("p->ref == 1", p->ref == 1);
826
827 if ((netif = ip_route(dest)) == NULL) {
828 LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
829 ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
830 IP_STATS_INC(ip.rterr);
831 return ERR_RTE;
832 }
833
834 return ip_output_if(p, src, dest, ttl, tos, proto, netif);
835 }
836
837 #if LWIP_NETIF_HWADDRHINT
838 /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
839 * before calling ip_output_if.
840 *
841 * @param p the packet to send (p->payload points to the data, e.g. next
842 protocol header; if dest == IP_HDRINCL, p already includes an IP
843 header and p->payload points to that IP header)
844 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
845 * IP address of the netif used to send is used as source address)
846 * @param dest the destination IP address to send the packet to
847 * @param ttl the TTL value to be set in the IP header
848 * @param tos the TOS value to be set in the IP header
849 * @param proto the PROTOCOL to be set in the IP header
850 * @param addr_hint address hint pointer set to netif->addr_hint before
851 * calling ip_output_if()
852 *
853 * @return ERR_RTE if no route is found
854 * see ip_output_if() for more return values
855 */
856 err_t
857 ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
858 u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
859 {
860 struct netif *netif;
861 err_t err;
862
863 /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
864 gets altered as the packet is passed down the stack */
865 LWIP_ASSERT("p->ref == 1", p->ref == 1);
866
867 if ((netif = ip_route(dest)) == NULL) {
868 LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
869 ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
870 IP_STATS_INC(ip.rterr);
871 return ERR_RTE;
872 }
873
874 NETIF_SET_HWADDRHINT(netif, addr_hint);
875 err = ip_output_if(p, src, dest, ttl, tos, proto, netif);
876 NETIF_SET_HWADDRHINT(netif, NULL);
877
878 return err;
879 }
880 #endif /* LWIP_NETIF_HWADDRHINT*/
881
882 #if IP_DEBUG
883 /* Print an IP header by using LWIP_DEBUGF
884 * @param p an IP packet, p->payload pointing to the IP header
885 */
886 void
887 ip_debug_print(struct pbuf *p)
888 {
889 struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
890
891 LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
892 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
893 LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" | 0x%02"X16_F" | %5"U16_F" | (v, hl, tos, len)\n",
894 IPH_V(iphdr),
895 IPH_HL(iphdr),
896 IPH_TOS(iphdr),
897 ntohs(IPH_LEN(iphdr))));
898 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
899 LWIP_DEBUGF(IP_DEBUG, ("| %5"U16_F" |%"U16_F"%"U16_F"%"U16_F"| %4"U16_F" | (id, flags, offset)\n",
900 ntohs(IPH_ID(iphdr)),
901 ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
902 ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
903 ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
904 ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
905 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
906 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | 0x%04"X16_F" | (ttl, proto, chksum)\n",
907 IPH_TTL(iphdr),
908 IPH_PROTO(iphdr),
909 ntohs(IPH_CHKSUM(iphdr))));
910 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
911 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (src)\n",
912 ip4_addr1_16(&iphdr->src),
913 ip4_addr2_16(&iphdr->src),
914 ip4_addr3_16(&iphdr->src),
915 ip4_addr4_16(&iphdr->src)));
916 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
917 LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (dest)\n",
918 ip4_addr1_16(&iphdr->dest),
919 ip4_addr2_16(&iphdr->dest),
920 ip4_addr3_16(&iphdr->dest),
921 ip4_addr4_16(&iphdr->dest)));
922 LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
923 }
924 #endif /* IP_DEBUG */
925