1 /**
2 * @file
3 * Address Resolution Protocol module for IP over Ethernet
4 *
5 * Functionally, ARP is divided into two parts. The first maps an IP address
6 * to a physical address when sending a packet, and the second part answers
7 * requests from other machines for our physical address.
8 *
9 * This implementation complies with RFC 826 (Ethernet ARP). It supports
10 * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6
11 * if an interface calls etharp_gratuitous(our_netif) upon address change.
12 */
13
14 /*
15 * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
16 * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
17 * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
18 * All rights reserved.
19 *
20 * Redistribution and use in source and binary forms, with or without modification,
21 * are permitted provided that the following conditions are met:
22 *
23 * 1. Redistributions of source code must retain the above copyright notice,
24 * this list of conditions and the following disclaimer.
25 * 2. Redistributions in binary form must reproduce the above copyright notice,
26 * this list of conditions and the following disclaimer in the documentation
27 * and/or other materials provided with the distribution.
28 * 3. The name of the author may not be used to endorse or promote products
29 * derived from this software without specific prior written permission.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
32 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
33 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
34 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
35 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
36 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
37 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
38 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
39 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
40 * OF SUCH DAMAGE.
41 *
42 * This file is part of the lwIP TCP/IP stack.
43 *
44 */
45
46 #include "lwip/opt.h"
47
48 #if LWIP_IPV4 && LWIP_ARP /* don't build if not configured for use in lwipopts.h */
49
50 #include "lwip/etharp.h"
51 #include "lwip/stats.h"
52 #include "lwip/snmp.h"
53 #include "lwip/dhcp.h"
54 #include "lwip/autoip.h"
55 #include "lwip/prot/iana.h"
56 #include "netif/ethernet.h"
57
58 #include <string.h>
59
60 #ifdef LWIP_HOOK_FILENAME
61 #include LWIP_HOOK_FILENAME
62 #endif
63
64 /** Re-request a used ARP entry 1 minute before it would expire to prevent
65 * breaking a steadily used connection because the ARP entry timed out. */
66 #define ARP_AGE_REREQUEST_USED_UNICAST (ARP_MAXAGE - 30)
67 #define ARP_AGE_REREQUEST_USED_BROADCAST (ARP_MAXAGE - 15)
68
69 /** the time an ARP entry stays pending after first request,
70 * for ARP_TMR_INTERVAL = 1000, this is
71 * 10 seconds.
72 *
73 * @internal Keep this number at least 2, otherwise it might
74 * run out instantly if the timeout occurs directly after a request.
75 */
76 #define ARP_MAXPENDING 5
77
78 /** ARP states */
79 enum etharp_state {
80 ETHARP_STATE_EMPTY = 0,
81 ETHARP_STATE_PENDING,
82 ETHARP_STATE_STABLE,
83 ETHARP_STATE_STABLE_REREQUESTING_1,
84 ETHARP_STATE_STABLE_REREQUESTING_2
85 #if ETHARP_SUPPORT_STATIC_ENTRIES
86 , ETHARP_STATE_STATIC
87 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
88 };
89
90 struct etharp_entry {
91 #if ARP_QUEUEING
92 /** Pointer to queue of pending outgoing packets on this ARP entry. */
93 struct etharp_q_entry *q;
94 #else /* ARP_QUEUEING */
95 /** Pointer to a single pending outgoing packet on this ARP entry. */
96 struct pbuf *q;
97 #endif /* ARP_QUEUEING */
98 ip4_addr_t ipaddr;
99 struct netif *netif;
100 struct eth_addr ethaddr;
101 u16_t ctime;
102 u8_t state;
103 };
104
105 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
106
107 #if !LWIP_NETIF_HWADDRHINT
108 static netif_addr_idx_t etharp_cached_entry;
109 #endif /* !LWIP_NETIF_HWADDRHINT */
110
111 /** Try hard to create a new entry - we want the IP address to appear in
112 the cache (even if this means removing an active entry or so). */
113 #define ETHARP_FLAG_TRY_HARD 1
114 #define ETHARP_FLAG_FIND_ONLY 2
115 #if ETHARP_SUPPORT_STATIC_ENTRIES
116 #define ETHARP_FLAG_STATIC_ENTRY 4
117 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
118
119 #if LWIP_NETIF_HWADDRHINT
120 #define ETHARP_SET_ADDRHINT(netif, addrhint) do { if (((netif) != NULL) && ((netif)->hints != NULL)) { \
121 (netif)->hints->addr_hint = (addrhint); }} while(0)
122 #else /* LWIP_NETIF_HWADDRHINT */
123 #define ETHARP_SET_ADDRHINT(netif, addrhint) (etharp_cached_entry = (addrhint))
124 #endif /* LWIP_NETIF_HWADDRHINT */
125
126
127 /* Check for maximum ARP_TABLE_SIZE */
128 #if (ARP_TABLE_SIZE > NETIF_ADDR_IDX_MAX)
129 #error "ARP_TABLE_SIZE must fit in an s16_t, you have to reduce it in your lwipopts.h"
130 #endif
131
132
133 static err_t etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr);
134 static err_t etharp_raw(struct netif *netif,
135 const struct eth_addr *ethsrc_addr, const struct eth_addr *ethdst_addr,
136 const struct eth_addr *hwsrc_addr, const ip4_addr_t *ipsrc_addr,
137 const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr,
138 const u16_t opcode);
139
140 #if ARP_QUEUEING
141 /**
142 * Free a complete queue of etharp entries
143 *
144 * @param q a qeueue of etharp_q_entry's to free
145 */
146 static void
free_etharp_q(struct etharp_q_entry * q)147 free_etharp_q(struct etharp_q_entry *q)
148 {
149 struct etharp_q_entry *r;
150 LWIP_ASSERT("q != NULL", q != NULL);
151 while (q) {
152 r = q;
153 q = q->next;
154 LWIP_ASSERT("r->p != NULL", (r->p != NULL));
155 pbuf_free(r->p);
156 memp_free(MEMP_ARP_QUEUE, r);
157 }
158 }
159 #else /* ARP_QUEUEING */
160
161 /** Compatibility define: free the queued pbuf */
162 #define free_etharp_q(q) pbuf_free(q)
163
164 #endif /* ARP_QUEUEING */
165
166 /** Clean up ARP table entries */
167 static void
etharp_free_entry(int i)168 etharp_free_entry(int i)
169 {
170 /* remove from SNMP ARP index tree */
171 mib2_remove_arp_entry(arp_table[i].netif, &arp_table[i].ipaddr);
172 /* and empty packet queue */
173 if (arp_table[i].q != NULL) {
174 /* remove all queued packets */
175 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_free_entry: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
176 free_etharp_q(arp_table[i].q);
177 arp_table[i].q = NULL;
178 }
179 /* recycle entry for re-use */
180 arp_table[i].state = ETHARP_STATE_EMPTY;
181 #ifdef LWIP_DEBUG
182 /* for debugging, clean out the complete entry */
183 arp_table[i].ctime = 0;
184 arp_table[i].netif = NULL;
185 ip4_addr_set_zero(&arp_table[i].ipaddr);
186 arp_table[i].ethaddr = ethzero;
187 #endif /* LWIP_DEBUG */
188 }
189
190 #if LWIP_LOWPOWER
191 #include "lwip/lowpower.h"
192 u32_t
etharp_tmr_tick(void)193 etharp_tmr_tick(void)
194 {
195 s32_t i;
196 u32_t tick = 0;
197 u32_t time;
198
199 for (i = 0; i < ARP_TABLE_SIZE; i++) {
200 u8_t state = arp_table[i].state;
201 if ((state != ETHARP_STATE_EMPTY)
202 #if ETHARP_SUPPORT_STATIC_ENTRIES
203 && (state != ETHARP_STATE_STATIC)
204 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
205 ) {
206 if (arp_table[i].state != ETHARP_STATE_STABLE) {
207 LWIP_DEBUGF(LOWPOWER_DEBUG, ("%s tmr tick: 1\n", "etharp_tmr_tick"));
208 return 1;
209 }
210 time = (u32_t)ARP_MAXAGE - arp_table[i].ctime;
211 SET_TMR_TICK(tick, time);
212 }
213 }
214 LWIP_DEBUGF(LOWPOWER_DEBUG, ("%s tmr tick: %u\n", "etharp_tmr_tick", tick));
215 return tick;
216 }
217 #endif /* LWIP_LOWPOWER */
218
219 /**
220 * Clears expired entries in the ARP table.
221 *
222 * This function should be called every ARP_TMR_INTERVAL milliseconds (1 second),
223 * in order to expire entries in the ARP table.
224 */
225 void
etharp_tmr(void)226 etharp_tmr(void)
227 {
228 int i;
229
230 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
231 /* remove expired entries from the ARP table */
232 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
233 u8_t state = arp_table[i].state;
234 if (state != ETHARP_STATE_EMPTY
235 #if ETHARP_SUPPORT_STATIC_ENTRIES
236 && (state != ETHARP_STATE_STATIC)
237 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
238 ) {
239 arp_table[i].ctime++;
240 if ((arp_table[i].ctime >= ARP_MAXAGE) ||
241 ((arp_table[i].state == ETHARP_STATE_PENDING) &&
242 (arp_table[i].ctime >= ARP_MAXPENDING))) {
243 /* pending or stable entry has become old! */
244 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %d.\n",
245 arp_table[i].state >= ETHARP_STATE_STABLE ? "stable" : "pending", i));
246 /* clean up entries that have just been expired */
247 etharp_free_entry(i);
248 } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_1) {
249 /* Don't send more than one request every 2 seconds. */
250 arp_table[i].state = ETHARP_STATE_STABLE_REREQUESTING_2;
251 } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_2) {
252 /* Reset state to stable, so that the next transmitted packet will
253 re-send an ARP request. */
254 arp_table[i].state = ETHARP_STATE_STABLE;
255 } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
256 /* still pending, resend an ARP query */
257 etharp_request(arp_table[i].netif, &arp_table[i].ipaddr);
258 }
259 }
260 }
261 }
262
263 /**
264 * Search the ARP table for a matching or new entry.
265 *
266 * If an IP address is given, return a pending or stable ARP entry that matches
267 * the address. If no match is found, create a new entry with this address set,
268 * but in state ETHARP_EMPTY. The caller must check and possibly change the
269 * state of the returned entry.
270 *
271 * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
272 *
273 * In all cases, attempt to create new entries from an empty entry. If no
274 * empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle
275 * old entries. Heuristic choose the least important entry for recycling.
276 *
277 * @param ipaddr IP address to find in ARP cache, or to add if not found.
278 * @param flags See @ref etharp_state
279 * @param netif netif related to this address (used for NETIF_HWADDRHINT)
280 *
281 * @return The ARP entry index that matched or is created, ERR_MEM if no
282 * entry is found or could be recycled.
283 */
284 static s16_t
etharp_find_entry(const ip4_addr_t * ipaddr,u8_t flags,struct netif * netif)285 etharp_find_entry(const ip4_addr_t *ipaddr, u8_t flags, struct netif *netif)
286 {
287 s16_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
288 s16_t empty = ARP_TABLE_SIZE;
289 s16_t i = 0;
290 /* oldest entry with packets on queue */
291 s16_t old_queue = ARP_TABLE_SIZE;
292 /* its age */
293 u16_t age_queue = 0, age_pending = 0, age_stable = 0;
294
295 LWIP_UNUSED_ARG(netif);
296
297 /**
298 * a) do a search through the cache, remember candidates
299 * b) select candidate entry
300 * c) create new entry
301 */
302
303 /* a) in a single search sweep, do all of this
304 * 1) remember the first empty entry (if any)
305 * 2) remember the oldest stable entry (if any)
306 * 3) remember the oldest pending entry without queued packets (if any)
307 * 4) remember the oldest pending entry with queued packets (if any)
308 * 5) search for a matching IP entry, either pending or stable
309 * until 5 matches, or all entries are searched for.
310 */
311
312 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
313 u8_t state = arp_table[i].state;
314 /* no empty entry found yet and now we do find one? */
315 if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) {
316 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_find_entry: found empty entry %d\n", (int)i));
317 /* remember first empty entry */
318 empty = i;
319 } else if (state != ETHARP_STATE_EMPTY) {
320 LWIP_ASSERT("state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE",
321 state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE);
322 /* if given, does IP address match IP address in ARP entry? */
323 if (ipaddr && ip4_addr_cmp(ipaddr, &arp_table[i].ipaddr)
324 #if ETHARP_TABLE_MATCH_NETIF
325 && ((netif == NULL) || (netif == arp_table[i].netif))
326 #endif /* ETHARP_TABLE_MATCH_NETIF */
327 ) {
328 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: found matching entry %d\n", (int)i));
329 /* found exact IP address match, simply bail out */
330 return i;
331 }
332 /* pending entry? */
333 if (state == ETHARP_STATE_PENDING) {
334 /* pending with queued packets? */
335 if (arp_table[i].q != NULL) {
336 if (arp_table[i].ctime >= age_queue) {
337 old_queue = i;
338 age_queue = arp_table[i].ctime;
339 }
340 } else
341 /* pending without queued packets? */
342 {
343 if (arp_table[i].ctime >= age_pending) {
344 old_pending = i;
345 age_pending = arp_table[i].ctime;
346 }
347 }
348 /* stable entry? */
349 } else if (state >= ETHARP_STATE_STABLE) {
350 #if ETHARP_SUPPORT_STATIC_ENTRIES
351 /* don't record old_stable for static entries since they never expire */
352 if (state < ETHARP_STATE_STATIC)
353 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
354 {
355 /* remember entry with oldest stable entry in oldest, its age in maxtime */
356 if (arp_table[i].ctime >= age_stable) {
357 old_stable = i;
358 age_stable = arp_table[i].ctime;
359 }
360 }
361 }
362 }
363 }
364 /* { we have no match } => try to create a new entry */
365
366 /* don't create new entry, only search? */
367 if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) ||
368 /* or no empty entry found and not allowed to recycle? */
369 ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) {
370 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty entry found and not allowed to recycle\n"));
371 return (s16_t)ERR_MEM;
372 }
373
374 /* b) choose the least destructive entry to recycle:
375 * 1) empty entry
376 * 2) oldest stable entry
377 * 3) oldest pending entry without queued packets
378 * 4) oldest pending entry with queued packets
379 *
380 * { ETHARP_FLAG_TRY_HARD is set at this point }
381 */
382
383 /* 1) empty entry available? */
384 if (empty < ARP_TABLE_SIZE) {
385 i = empty;
386 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting empty entry %d\n", (int)i));
387 } else {
388 /* 2) found recyclable stable entry? */
389 if (old_stable < ARP_TABLE_SIZE) {
390 /* recycle oldest stable*/
391 i = old_stable;
392 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest stable entry %d\n", (int)i));
393 /* no queued packets should exist on stable entries */
394 LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
395 /* 3) found recyclable pending entry without queued packets? */
396 } else if (old_pending < ARP_TABLE_SIZE) {
397 /* recycle oldest pending */
398 i = old_pending;
399 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %d (without queue)\n", (int)i));
400 /* 4) found recyclable pending entry with queued packets? */
401 } else if (old_queue < ARP_TABLE_SIZE) {
402 /* recycle oldest pending (queued packets are free in etharp_free_entry) */
403 i = old_queue;
404 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %d, freeing packet queue %p\n", (int)i, (void *)(arp_table[i].q)));
405 /* no empty or recyclable entries found */
406 } else {
407 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty or recyclable entries found\n"));
408 return (s16_t)ERR_MEM;
409 }
410
411 /* { empty or recyclable entry found } */
412 LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
413 etharp_free_entry(i);
414 }
415
416 LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
417 LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY",
418 arp_table[i].state == ETHARP_STATE_EMPTY);
419
420 /* IP address given? */
421 if (ipaddr != NULL) {
422 /* set IP address */
423 ip4_addr_copy(arp_table[i].ipaddr, *ipaddr);
424 }
425 arp_table[i].ctime = 0;
426 #if ETHARP_TABLE_MATCH_NETIF
427 arp_table[i].netif = netif;
428 #endif /* ETHARP_TABLE_MATCH_NETIF */
429 return (s16_t)i;
430 }
431
432 /**
433 * Update (or insert) a IP/MAC address pair in the ARP cache.
434 *
435 * If a pending entry is resolved, any queued packets will be sent
436 * at this point.
437 *
438 * @param netif netif related to this entry (used for NETIF_ADDRHINT)
439 * @param ipaddr IP address of the inserted ARP entry.
440 * @param ethaddr Ethernet address of the inserted ARP entry.
441 * @param flags See @ref etharp_state
442 *
443 * @return
444 * - ERR_OK Successfully updated ARP cache.
445 * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
446 * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
447 *
448 * @see pbuf_free()
449 */
450 static err_t
etharp_update_arp_entry(struct netif * netif,const ip4_addr_t * ipaddr,struct eth_addr * ethaddr,u8_t flags)451 etharp_update_arp_entry(struct netif *netif, const ip4_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
452 {
453 s16_t i;
454 LWIP_ASSERT("netif->hwaddr_len == ETH_HWADDR_LEN", netif->hwaddr_len == ETH_HWADDR_LEN);
455 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
456 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
457 (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2],
458 (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5]));
459 /* non-unicast address? */
460 if (ip4_addr_isany(ipaddr) ||
461 ip4_addr_isbroadcast(ipaddr, netif) ||
462 ip4_addr_ismulticast(ipaddr)) {
463 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
464 return ERR_ARG;
465 }
466 /* find or create ARP entry */
467 i = etharp_find_entry(ipaddr, flags, netif);
468 /* bail out if no entry could be found */
469 if (i < 0) {
470 return (err_t)i;
471 }
472
473 #if ETHARP_SUPPORT_STATIC_ENTRIES
474 if (flags & ETHARP_FLAG_STATIC_ENTRY) {
475 /* record static type */
476 arp_table[i].state = ETHARP_STATE_STATIC;
477 } else if (arp_table[i].state == ETHARP_STATE_STATIC) {
478 /* found entry is a static type, don't overwrite it */
479 return ERR_VAL;
480 } else
481 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
482 {
483 /* mark it stable */
484 arp_table[i].state = ETHARP_STATE_STABLE;
485 }
486
487 /* record network interface */
488 arp_table[i].netif = netif;
489 /* insert in SNMP ARP index tree */
490 mib2_add_arp_entry(netif, &arp_table[i].ipaddr);
491
492 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: updating stable entry %"S16_F"\n", i));
493 /* update address */
494 SMEMCPY(&arp_table[i].ethaddr, ethaddr, ETH_HWADDR_LEN);
495 /* reset time stamp */
496 arp_table[i].ctime = 0;
497 /* this is where we will send out queued packets! */
498 #if ARP_QUEUEING
499 while (arp_table[i].q != NULL) {
500 struct pbuf *p;
501 /* remember remainder of queue */
502 struct etharp_q_entry *q = arp_table[i].q;
503 /* pop first item off the queue */
504 arp_table[i].q = q->next;
505 /* get the packet pointer */
506 p = q->p;
507 /* now queue entry can be freed */
508 memp_free(MEMP_ARP_QUEUE, q);
509 #else /* ARP_QUEUEING */
510 if (arp_table[i].q != NULL) {
511 struct pbuf *p = arp_table[i].q;
512 arp_table[i].q = NULL;
513 #endif /* ARP_QUEUEING */
514 /* send the queued IP packet */
515 ethernet_output(netif, p, (struct eth_addr *)(netif->hwaddr), ethaddr, ETHTYPE_IP);
516 /* free the queued IP packet */
517 pbuf_free(p);
518 }
519 return ERR_OK;
520 }
521
522 #if ETHARP_SUPPORT_STATIC_ENTRIES
523 /** Add a new static entry to the ARP table. If an entry exists for the
524 * specified IP address, this entry is overwritten.
525 * If packets are queued for the specified IP address, they are sent out.
526 *
527 * @param ipaddr IP address for the new static entry
528 * @param ethaddr ethernet address for the new static entry
529 * @return See return values of etharp_add_static_entry
530 */
531 err_t
532 etharp_add_static_entry(const ip4_addr_t *ipaddr, struct eth_addr *ethaddr)
533 {
534 struct netif *netif;
535 LWIP_ASSERT_CORE_LOCKED();
536 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_add_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
537 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
538 (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2],
539 (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5]));
540 #ifdef LOSCFG_NET_CONTAINER
541 netif = ip4_route(ipaddr, get_root_net_group());
542 #else
543 netif = ip4_route(ipaddr);
544 #endif
545 if (netif == NULL) {
546 return ERR_RTE;
547 }
548
549 return etharp_update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY);
550 }
551
552 /** Remove a static entry from the ARP table previously added with a call to
553 * etharp_add_static_entry.
554 *
555 * @param ipaddr IP address of the static entry to remove
556 * @return ERR_OK: entry removed
557 * ERR_MEM: entry wasn't found
558 * ERR_ARG: entry wasn't a static entry but a dynamic one
559 */
560 err_t
561 etharp_remove_static_entry(const ip4_addr_t *ipaddr)
562 {
563 s16_t i;
564 LWIP_ASSERT_CORE_LOCKED();
565 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
566 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
567
568 /* find or create ARP entry */
569 i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, NULL);
570 /* bail out if no entry could be found */
571 if (i < 0) {
572 return (err_t)i;
573 }
574
575 if (arp_table[i].state != ETHARP_STATE_STATIC) {
576 /* entry wasn't a static entry, cannot remove it */
577 return ERR_ARG;
578 }
579 /* entry found, free it */
580 etharp_free_entry(i);
581 return ERR_OK;
582 }
583 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
584
585 /**
586 * Remove all ARP table entries of the specified netif.
587 *
588 * @param netif points to a network interface
589 */
590 void
591 etharp_cleanup_netif(struct netif *netif)
592 {
593 int i;
594
595 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
596 u8_t state = arp_table[i].state;
597 if ((state != ETHARP_STATE_EMPTY) && (arp_table[i].netif == netif)) {
598 etharp_free_entry(i);
599 }
600 }
601 }
602
603 /**
604 * Finds (stable) ethernet/IP address pair from ARP table
605 * using interface and IP address index.
606 * @note the addresses in the ARP table are in network order!
607 *
608 * @param netif points to interface index
609 * @param ipaddr points to the (network order) IP address index
610 * @param eth_ret points to return pointer
611 * @param ip_ret points to return pointer
612 * @return table index if found, -1 otherwise
613 */
614 ssize_t
615 etharp_find_addr(struct netif *netif, const ip4_addr_t *ipaddr,
616 struct eth_addr **eth_ret, const ip4_addr_t **ip_ret)
617 {
618 s16_t i;
619
620 LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL",
621 eth_ret != NULL && ip_ret != NULL);
622
623 LWIP_UNUSED_ARG(netif);
624
625 i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, netif);
626 if ((i >= 0) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
627 *eth_ret = &arp_table[i].ethaddr;
628 *ip_ret = &arp_table[i].ipaddr;
629 return i;
630 }
631 return -1;
632 }
633
634 /**
635 * Possibility to iterate over stable ARP table entries
636 *
637 * @param i entry number, 0 to ARP_TABLE_SIZE
638 * @param ipaddr return value: IP address
639 * @param netif return value: points to interface
640 * @param eth_ret return value: ETH address
641 * @return 1 on valid index, 0 otherwise
642 */
643 int
644 etharp_get_entry(size_t i, ip4_addr_t **ipaddr, struct netif **netif, struct eth_addr **eth_ret)
645 {
646 LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
647 LWIP_ASSERT("netif != NULL", netif != NULL);
648 LWIP_ASSERT("eth_ret != NULL", eth_ret != NULL);
649
650 if ((i < ARP_TABLE_SIZE) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
651 *ipaddr = &arp_table[i].ipaddr;
652 *netif = arp_table[i].netif;
653 *eth_ret = &arp_table[i].ethaddr;
654 return 1;
655 } else {
656 return 0;
657 }
658 }
659
660 /**
661 * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache
662 * send out queued IP packets. Updates cache with snooped address pairs.
663 *
664 * Should be called for incoming ARP packets. The pbuf in the argument
665 * is freed by this function.
666 *
667 * @param p The ARP packet that arrived on netif. Is freed by this function.
668 * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
669 *
670 * @see pbuf_free()
671 */
672 void
673 etharp_input(struct pbuf *p, struct netif *netif)
674 {
675 struct etharp_hdr *hdr;
676 /* these are aligned properly, whereas the ARP header fields might not be */
677 ip4_addr_t sipaddr, dipaddr;
678 u8_t for_us;
679
680 LWIP_ASSERT_CORE_LOCKED();
681
682 LWIP_ERROR("netif != NULL", (netif != NULL), return;);
683
684 hdr = (struct etharp_hdr *)p->payload;
685
686 /* RFC 826 "Packet Reception": */
687 if ((hdr->hwtype != PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET)) ||
688 (hdr->hwlen != ETH_HWADDR_LEN) ||
689 (hdr->protolen != sizeof(ip4_addr_t)) ||
690 (hdr->proto != PP_HTONS(ETHTYPE_IP))) {
691 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
692 ("etharp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
693 hdr->hwtype, (u16_t)hdr->hwlen, hdr->proto, (u16_t)hdr->protolen));
694 ETHARP_STATS_INC(etharp.proterr);
695 ETHARP_STATS_INC(etharp.drop);
696 pbuf_free(p);
697 return;
698 }
699 ETHARP_STATS_INC(etharp.recv);
700
701 #if LWIP_AUTOIP
702 /* We have to check if a host already has configured our random
703 * created link local address and continuously check if there is
704 * a host with this IP-address so we can detect collisions */
705 autoip_arp_reply(netif, hdr);
706 #endif /* LWIP_AUTOIP */
707
708 /* Copy struct ip4_addr_wordaligned to aligned ip4_addr, to support compilers without
709 * structure packing (not using structure copy which breaks strict-aliasing rules). */
710 IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&sipaddr, &hdr->sipaddr);
711 IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&dipaddr, &hdr->dipaddr);
712
713 /* this interface is not configured? */
714 if (ip4_addr_isany_val(*netif_ip4_addr(netif))) {
715 for_us = 0;
716 } else {
717 /* ARP packet directed to us? */
718 for_us = (u8_t)ip4_addr_cmp(&dipaddr, netif_ip4_addr(netif));
719 }
720
721 /* ARP message directed to us?
722 -> add IP address in ARP cache; assume requester wants to talk to us,
723 can result in directly sending the queued packets for this host.
724 ARP message not directed to us?
725 -> update the source IP address in the cache, if present */
726 etharp_update_arp_entry(netif, &sipaddr, &(hdr->shwaddr),
727 for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
728
729 /* now act on the message itself */
730 switch (hdr->opcode) {
731 /* ARP request? */
732 case PP_HTONS(ARP_REQUEST):
733 /* ARP request. If it asked for our address, we send out a
734 * reply. In any case, we time-stamp any existing ARP entry,
735 * and possibly send out an IP packet that was queued on it. */
736
737 LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: incoming ARP request\n"));
738 /* ARP request for our address? */
739 if (for_us) {
740 /* send ARP response */
741 etharp_raw(netif,
742 (struct eth_addr *)netif->hwaddr, &hdr->shwaddr,
743 (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif),
744 &hdr->shwaddr, &sipaddr,
745 ARP_REPLY);
746 /* we are not configured? */
747 } else if (ip4_addr_isany_val(*netif_ip4_addr(netif))) {
748 /* { for_us == 0 and netif->ip_addr.addr == 0 } */
749 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: we are unconfigured, ARP request ignored.\n"));
750 /* request was not directed to us */
751 } else {
752 /* { for_us == 0 and netif->ip_addr.addr != 0 } */
753 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: ARP request was not for us.\n"));
754 }
755 break;
756 case PP_HTONS(ARP_REPLY):
757 /* ARP reply. We already updated the ARP cache earlier. */
758 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: incoming ARP reply\n"));
759 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
760 /* DHCP wants to know about ARP replies from any host with an
761 * IP address also offered to us by the DHCP server. We do not
762 * want to take a duplicate IP address on a single network.
763 * @todo How should we handle redundant (fail-over) interfaces? */
764 dhcp_arp_reply(netif, &sipaddr);
765 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
766 break;
767 default:
768 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: ARP unknown opcode type %"S16_F"\n", lwip_htons(hdr->opcode)));
769 ETHARP_STATS_INC(etharp.err);
770 break;
771 }
772 /* free ARP packet */
773 pbuf_free(p);
774 }
775
776 /** Just a small helper function that sends a pbuf to an ethernet address
777 * in the arp_table specified by the index 'arp_idx'.
778 */
779 static err_t
780 etharp_output_to_arp_index(struct netif *netif, struct pbuf *q, netif_addr_idx_t arp_idx)
781 {
782 LWIP_ASSERT("arp_table[arp_idx].state >= ETHARP_STATE_STABLE",
783 arp_table[arp_idx].state >= ETHARP_STATE_STABLE);
784 /* if arp table entry is about to expire: re-request it,
785 but only if its state is ETHARP_STATE_STABLE to prevent flooding the
786 network with ARP requests if this address is used frequently. */
787 if (arp_table[arp_idx].state == ETHARP_STATE_STABLE) {
788 if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_BROADCAST) {
789 /* issue a standard request using broadcast */
790 if (etharp_request(netif, &arp_table[arp_idx].ipaddr) == ERR_OK) {
791 arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1;
792 }
793 } else if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_UNICAST) {
794 /* issue a unicast request (for 15 seconds) to prevent unnecessary broadcast */
795 if (etharp_request_dst(netif, &arp_table[arp_idx].ipaddr, &arp_table[arp_idx].ethaddr) == ERR_OK) {
796 arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1;
797 }
798 }
799 }
800
801 return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), &arp_table[arp_idx].ethaddr, ETHTYPE_IP);
802 }
803
804 /**
805 * Resolve and fill-in Ethernet address header for outgoing IP packet.
806 *
807 * For IP multicast and broadcast, corresponding Ethernet addresses
808 * are selected and the packet is transmitted on the link.
809 *
810 * For unicast addresses, the packet is submitted to etharp_query(). In
811 * case the IP address is outside the local network, the IP address of
812 * the gateway is used.
813 *
814 * @param netif The lwIP network interface which the IP packet will be sent on.
815 * @param q The pbuf(s) containing the IP packet to be sent.
816 * @param ipaddr The IP address of the packet destination.
817 *
818 * @return
819 * - ERR_RTE No route to destination (no gateway to external networks),
820 * or the return type of either etharp_query() or ethernet_output().
821 */
822 err_t
823 etharp_output(struct netif *netif, struct pbuf *q, const ip4_addr_t *ipaddr)
824 {
825 const struct eth_addr *dest;
826 struct eth_addr mcastaddr;
827 const ip4_addr_t *dst_addr = ipaddr;
828
829 LWIP_ASSERT_CORE_LOCKED();
830 LWIP_ASSERT("netif != NULL", netif != NULL);
831 LWIP_ASSERT("q != NULL", q != NULL);
832 LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
833
834 /* Determine on destination hardware address. Broadcasts and multicasts
835 * are special, other IP addresses are looked up in the ARP table. */
836
837 /* broadcast destination IP address? */
838 if (ip4_addr_isbroadcast(ipaddr, netif)) {
839 /* broadcast on Ethernet also */
840 dest = (const struct eth_addr *)ðbroadcast;
841 /* multicast destination IP address? */
842 } else if (ip4_addr_ismulticast(ipaddr)) {
843 /* Hash IP multicast address to MAC address.*/
844 mcastaddr.addr[0] = LL_IP4_MULTICAST_ADDR_0;
845 mcastaddr.addr[1] = LL_IP4_MULTICAST_ADDR_1;
846 mcastaddr.addr[2] = LL_IP4_MULTICAST_ADDR_2;
847 mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
848 mcastaddr.addr[4] = ip4_addr3(ipaddr);
849 mcastaddr.addr[5] = ip4_addr4(ipaddr);
850 /* destination Ethernet address is multicast */
851 dest = &mcastaddr;
852 /* unicast destination IP address? */
853 } else {
854 netif_addr_idx_t i;
855 /* outside local network? if so, this can neither be a global broadcast nor
856 a subnet broadcast. */
857 if (!ip4_addr_netcmp(ipaddr, netif_ip4_addr(netif), netif_ip4_netmask(netif)) &&
858 !ip4_addr_islinklocal(ipaddr)) {
859 #if LWIP_AUTOIP
860 struct ip_hdr *iphdr = LWIP_ALIGNMENT_CAST(struct ip_hdr *, q->payload);
861 /* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with
862 a link-local source address must always be "directly to its destination
863 on the same physical link. The host MUST NOT send the packet to any
864 router for forwarding". */
865 if (!ip4_addr_islinklocal(&iphdr->src))
866 #endif /* LWIP_AUTOIP */
867 {
868 #ifdef LWIP_HOOK_ETHARP_GET_GW
869 /* For advanced routing, a single default gateway might not be enough, so get
870 the IP address of the gateway to handle the current destination address. */
871 dst_addr = LWIP_HOOK_ETHARP_GET_GW(netif, ipaddr);
872 if (dst_addr == NULL)
873 #endif /* LWIP_HOOK_ETHARP_GET_GW */
874 {
875 /* interface has default gateway? */
876 if (!ip4_addr_isany_val(*netif_ip4_gw(netif))) {
877 /* send to hardware address of default gateway IP address */
878 dst_addr = netif_ip4_gw(netif);
879 /* no default gateway available */
880 } else {
881 /* no route to destination error (default gateway missing) */
882 return ERR_RTE;
883 }
884 }
885 }
886 }
887 #if LWIP_NETIF_HWADDRHINT
888 if (netif->hints != NULL) {
889 /* per-pcb cached entry was given */
890 netif_addr_idx_t etharp_cached_entry = netif->hints->addr_hint;
891 if (etharp_cached_entry < ARP_TABLE_SIZE) {
892 #endif /* LWIP_NETIF_HWADDRHINT */
893 if ((arp_table[etharp_cached_entry].state >= ETHARP_STATE_STABLE) &&
894 #if ETHARP_TABLE_MATCH_NETIF
895 (arp_table[etharp_cached_entry].netif == netif) &&
896 #endif
897 (ip4_addr_cmp(dst_addr, &arp_table[etharp_cached_entry].ipaddr))) {
898 /* the per-pcb-cached entry is stable and the right one! */
899 ETHARP_STATS_INC(etharp.cachehit);
900 return etharp_output_to_arp_index(netif, q, etharp_cached_entry);
901 }
902 #if LWIP_NETIF_HWADDRHINT
903 }
904 }
905 #endif /* LWIP_NETIF_HWADDRHINT */
906
907 /* find stable entry: do this here since this is a critical path for
908 throughput and etharp_find_entry() is kind of slow */
909 for (i = 0; i < ARP_TABLE_SIZE; i++) {
910 if ((arp_table[i].state >= ETHARP_STATE_STABLE) &&
911 #if ETHARP_TABLE_MATCH_NETIF
912 (arp_table[i].netif == netif) &&
913 #endif
914 (ip4_addr_cmp(dst_addr, &arp_table[i].ipaddr))) {
915 /* found an existing, stable entry */
916 ETHARP_SET_ADDRHINT(netif, i);
917 return etharp_output_to_arp_index(netif, q, i);
918 }
919 }
920 /* no stable entry found, use the (slower) query function:
921 queue on destination Ethernet address belonging to ipaddr */
922 return etharp_query(netif, dst_addr, q);
923 }
924
925 /* continuation for multicast/broadcast destinations */
926 /* obtain source Ethernet address of the given interface */
927 /* send packet directly on the link */
928 return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), dest, ETHTYPE_IP);
929 }
930
931 /**
932 * Send an ARP request for the given IP address and/or queue a packet.
933 *
934 * If the IP address was not yet in the cache, a pending ARP cache entry
935 * is added and an ARP request is sent for the given address. The packet
936 * is queued on this entry.
937 *
938 * If the IP address was already pending in the cache, a new ARP request
939 * is sent for the given address. The packet is queued on this entry.
940 *
941 * If the IP address was already stable in the cache, and a packet is
942 * given, it is directly sent and no ARP request is sent out.
943 *
944 * If the IP address was already stable in the cache, and no packet is
945 * given, an ARP request is sent out.
946 *
947 * @param netif The lwIP network interface on which ipaddr
948 * must be queried for.
949 * @param ipaddr The IP address to be resolved.
950 * @param q If non-NULL, a pbuf that must be delivered to the IP address.
951 * q is not freed by this function.
952 *
953 * @note q must only be ONE packet, not a packet queue!
954 *
955 * @return
956 * - ERR_BUF Could not make room for Ethernet header.
957 * - ERR_MEM Hardware address unknown, and no more ARP entries available
958 * to query for address or queue the packet.
959 * - ERR_MEM Could not queue packet due to memory shortage.
960 * - ERR_RTE No route to destination (no gateway to external networks).
961 * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
962 *
963 */
964 err_t
965 etharp_query(struct netif *netif, const ip4_addr_t *ipaddr, struct pbuf *q)
966 {
967 struct eth_addr *srcaddr = (struct eth_addr *)netif->hwaddr;
968 err_t result = ERR_MEM;
969 int is_new_entry = 0;
970 s16_t i_err;
971 netif_addr_idx_t i;
972
973 /* non-unicast address? */
974 if (ip4_addr_isbroadcast(ipaddr, netif) ||
975 ip4_addr_ismulticast(ipaddr) ||
976 ip4_addr_isany(ipaddr)) {
977 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
978 return ERR_ARG;
979 }
980
981 /* find entry in ARP cache, ask to create entry if queueing packet */
982 i_err = etharp_find_entry(ipaddr, ETHARP_FLAG_TRY_HARD, netif);
983
984 /* could not find or create entry? */
985 if (i_err < 0) {
986 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
987 if (q) {
988 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
989 ETHARP_STATS_INC(etharp.memerr);
990 }
991 return (err_t)i_err;
992 }
993 LWIP_ASSERT("type overflow", (size_t)i_err < NETIF_ADDR_IDX_MAX);
994 i = (netif_addr_idx_t)i_err;
995
996 /* mark a fresh entry as pending (we just sent a request) */
997 if (arp_table[i].state == ETHARP_STATE_EMPTY) {
998 is_new_entry = 1;
999 arp_table[i].state = ETHARP_STATE_PENDING;
1000 /* record network interface for re-sending arp request in etharp_tmr */
1001 arp_table[i].netif = netif;
1002 }
1003
1004 /* { i is either a STABLE or (new or existing) PENDING entry } */
1005 LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
1006 ((arp_table[i].state == ETHARP_STATE_PENDING) ||
1007 (arp_table[i].state >= ETHARP_STATE_STABLE)));
1008
1009 /* do we have a new entry? or an implicit query request? */
1010 if (is_new_entry || (q == NULL)) {
1011 /* try to resolve it; send out ARP request */
1012 result = etharp_request(netif, ipaddr);
1013 if (result != ERR_OK) {
1014 /* ARP request couldn't be sent */
1015 /* We don't re-send arp request in etharp_tmr, but we still queue packets,
1016 since this failure could be temporary, and the next packet calling
1017 etharp_query again could lead to sending the queued packets. */
1018 } else {
1019 /* ARP request successfully sent */
1020 if ((arp_table[i].state == ETHARP_STATE_PENDING) && !is_new_entry) {
1021 /* A new ARP request has been sent for a pending entry. Reset the ctime to
1022 not let it expire too fast. */
1023 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: reset ctime for entry %"S16_F"\n", (s16_t)i));
1024 arp_table[i].ctime = 0;
1025 }
1026 }
1027 if (q == NULL) {
1028 return result;
1029 }
1030 }
1031
1032 /* packet given? */
1033 LWIP_ASSERT("q != NULL", q != NULL);
1034 /* stable entry? */
1035 if (arp_table[i].state >= ETHARP_STATE_STABLE) {
1036 /* we have a valid IP->Ethernet address mapping */
1037 ETHARP_SET_ADDRHINT(netif, i);
1038 /* send the packet */
1039 result = ethernet_output(netif, q, srcaddr, &(arp_table[i].ethaddr), ETHTYPE_IP);
1040 /* pending entry? (either just created or already pending */
1041 } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
1042 /* entry is still pending, queue the given packet 'q' */
1043 struct pbuf *p;
1044 int copy_needed = 0;
1045 /* IF q includes a pbuf that must be copied, copy the whole chain into a
1046 * new PBUF_RAM. See the definition of PBUF_NEEDS_COPY for details. */
1047 p = q;
1048 while (p) {
1049 LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
1050 if (PBUF_NEEDS_COPY(p)) {
1051 copy_needed = 1;
1052 break;
1053 }
1054 p = p->next;
1055 }
1056 if (copy_needed) {
1057 /* copy the whole packet into new pbufs */
1058 p = pbuf_clone(PBUF_LINK, PBUF_RAM, q);
1059 } else {
1060 /* referencing the old pbuf is enough */
1061 p = q;
1062 pbuf_ref(p);
1063 }
1064 /* packet could be taken over? */
1065 if (p != NULL) {
1066 /* queue packet ... */
1067 #if ARP_QUEUEING
1068 struct etharp_q_entry *new_entry;
1069 /* allocate a new arp queue entry */
1070 new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
1071 if (new_entry != NULL) {
1072 unsigned int qlen = 0;
1073 new_entry->next = 0;
1074 new_entry->p = p;
1075 if (arp_table[i].q != NULL) {
1076 /* queue was already existent, append the new entry to the end */
1077 struct etharp_q_entry *r;
1078 r = arp_table[i].q;
1079 qlen++;
1080 while (r->next != NULL) {
1081 r = r->next;
1082 qlen++;
1083 }
1084 r->next = new_entry;
1085 } else {
1086 /* queue did not exist, first item in queue */
1087 arp_table[i].q = new_entry;
1088 }
1089 #if ARP_QUEUE_LEN
1090 if (qlen >= ARP_QUEUE_LEN) {
1091 struct etharp_q_entry *old;
1092 old = arp_table[i].q;
1093 arp_table[i].q = arp_table[i].q->next;
1094 pbuf_free(old->p);
1095 memp_free(MEMP_ARP_QUEUE, old);
1096 }
1097 #endif
1098 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"U16_F"\n", (void *)q, i));
1099 result = ERR_OK;
1100 } else {
1101 /* the pool MEMP_ARP_QUEUE is empty */
1102 pbuf_free(p);
1103 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
1104 result = ERR_MEM;
1105 }
1106 #else /* ARP_QUEUEING */
1107 /* always queue one packet per ARP request only, freeing a previously queued packet */
1108 if (arp_table[i].q != NULL) {
1109 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: dropped previously queued packet %p for ARP entry %"U16_F"\n", (void *)q, (u16_t)i));
1110 pbuf_free(arp_table[i].q);
1111 }
1112 arp_table[i].q = p;
1113 result = ERR_OK;
1114 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"U16_F"\n", (void *)q, (u16_t)i));
1115 #endif /* ARP_QUEUEING */
1116 } else {
1117 ETHARP_STATS_INC(etharp.memerr);
1118 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
1119 result = ERR_MEM;
1120 }
1121 }
1122 return result;
1123 }
1124
1125 /**
1126 * Send a raw ARP packet (opcode and all addresses can be modified)
1127 *
1128 * @param netif the lwip network interface on which to send the ARP packet
1129 * @param ethsrc_addr the source MAC address for the ethernet header
1130 * @param ethdst_addr the destination MAC address for the ethernet header
1131 * @param hwsrc_addr the source MAC address for the ARP protocol header
1132 * @param ipsrc_addr the source IP address for the ARP protocol header
1133 * @param hwdst_addr the destination MAC address for the ARP protocol header
1134 * @param ipdst_addr the destination IP address for the ARP protocol header
1135 * @param opcode the type of the ARP packet
1136 * @return ERR_OK if the ARP packet has been sent
1137 * ERR_MEM if the ARP packet couldn't be allocated
1138 * any other err_t on failure
1139 */
1140 static err_t
1141 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
1142 const struct eth_addr *ethdst_addr,
1143 const struct eth_addr *hwsrc_addr, const ip4_addr_t *ipsrc_addr,
1144 const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr,
1145 const u16_t opcode)
1146 {
1147 struct pbuf *p;
1148 err_t result = ERR_OK;
1149 struct etharp_hdr *hdr;
1150
1151 LWIP_ASSERT("netif != NULL", netif != NULL);
1152
1153 /* allocate a pbuf for the outgoing ARP request packet */
1154 p = pbuf_alloc(PBUF_LINK, SIZEOF_ETHARP_HDR, PBUF_RAM);
1155 /* could allocate a pbuf for an ARP request? */
1156 if (p == NULL) {
1157 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
1158 ("etharp_raw: could not allocate pbuf for ARP request.\n"));
1159 ETHARP_STATS_INC(etharp.memerr);
1160 return ERR_MEM;
1161 }
1162 LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
1163 (p->len >= SIZEOF_ETHARP_HDR));
1164
1165 hdr = (struct etharp_hdr *)p->payload;
1166 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
1167 hdr->opcode = lwip_htons(opcode);
1168
1169 LWIP_ASSERT("netif->hwaddr_len must be the same as ETH_HWADDR_LEN for etharp!",
1170 (netif->hwaddr_len == ETH_HWADDR_LEN));
1171
1172 /* Write the ARP MAC-Addresses */
1173 SMEMCPY(&hdr->shwaddr, hwsrc_addr, ETH_HWADDR_LEN);
1174 SMEMCPY(&hdr->dhwaddr, hwdst_addr, ETH_HWADDR_LEN);
1175 /* Copy struct ip4_addr_wordaligned to aligned ip4_addr, to support compilers without
1176 * structure packing. */
1177 IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->sipaddr, ipsrc_addr);
1178 IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->dipaddr, ipdst_addr);
1179
1180 hdr->hwtype = PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET);
1181 hdr->proto = PP_HTONS(ETHTYPE_IP);
1182 /* set hwlen and protolen */
1183 hdr->hwlen = ETH_HWADDR_LEN;
1184 hdr->protolen = sizeof(ip4_addr_t);
1185
1186 /* send ARP query */
1187 #if LWIP_AUTOIP
1188 /* If we are using Link-Local, all ARP packets that contain a Link-Local
1189 * 'sender IP address' MUST be sent using link-layer broadcast instead of
1190 * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
1191 if (ip4_addr_islinklocal(ipsrc_addr)) {
1192 ethernet_output(netif, p, ethsrc_addr, ðbroadcast, ETHTYPE_ARP);
1193 } else
1194 #endif /* LWIP_AUTOIP */
1195 {
1196 ethernet_output(netif, p, ethsrc_addr, ethdst_addr, ETHTYPE_ARP);
1197 }
1198
1199 ETHARP_STATS_INC(etharp.xmit);
1200 /* free ARP query packet */
1201 pbuf_free(p);
1202 p = NULL;
1203 /* could not allocate pbuf for ARP request */
1204
1205 return result;
1206 }
1207
1208 /**
1209 * Send an ARP request packet asking for ipaddr to a specific eth address.
1210 * Used to send unicast request to refresh the ARP table just before an entry
1211 * times out
1212 *
1213 * @param netif the lwip network interface on which to send the request
1214 * @param ipaddr the IP address for which to ask
1215 * @param hw_dst_addr the ethernet address to send this packet to
1216 * @return ERR_OK if the request has been sent
1217 * ERR_MEM if the ARP packet couldn't be allocated
1218 * any other err_t on failure
1219 */
1220 static err_t
1221 etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr)
1222 {
1223 return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, hw_dst_addr,
1224 (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif), ðzero,
1225 ipaddr, ARP_REQUEST);
1226 }
1227
1228 /**
1229 * Send an ARP request packet asking for ipaddr.
1230 *
1231 * @param netif the lwip network interface on which to send the request
1232 * @param ipaddr the IP address for which to ask
1233 * @return ERR_OK if the request has been sent
1234 * ERR_MEM if the ARP packet couldn't be allocated
1235 * any other err_t on failure
1236 */
1237 err_t
1238 etharp_request(struct netif *netif, const ip4_addr_t *ipaddr)
1239 {
1240 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
1241 return etharp_request_dst(netif, ipaddr, ðbroadcast);
1242 }
1243
1244 #endif /* LWIP_IPV4 && LWIP_ARP */
1245