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1 office 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_ARP || LWIP_ETHERNET
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 #if LWIP_IPV4 && LWIP_ARP /* don't build if not configured for use in lwipopts.h */
65  
66 /** Re-request a used ARP entry 1 minute before it would expire to prevent
67 * breaking a steadily used connection because the ARP entry timed out. */
68 #define ARP_AGE_REREQUEST_USED_UNICAST (ARP_MAXAGE - 30)
69 #define ARP_AGE_REREQUEST_USED_BROADCAST (ARP_MAXAGE - 15)
70  
71 /** the time an ARP entry stays pending after first request,
72 * for ARP_TMR_INTERVAL = 1000, this is
73 * 10 seconds.
74 *
75 * @internal Keep this number at least 2, otherwise it might
76 * run out instantly if the timeout occurs directly after a request.
77 */
78 #define ARP_MAXPENDING 5
79  
80 /** ARP states */
81 enum etharp_state {
82 ETHARP_STATE_EMPTY = 0,
83 ETHARP_STATE_PENDING,
84 ETHARP_STATE_STABLE,
85 ETHARP_STATE_STABLE_REREQUESTING_1,
86 ETHARP_STATE_STABLE_REREQUESTING_2
87 #if ETHARP_SUPPORT_STATIC_ENTRIES
88 , ETHARP_STATE_STATIC
89 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
90 };
91  
92 struct etharp_entry {
93 #if ARP_QUEUEING
94 /** Pointer to queue of pending outgoing packets on this ARP entry. */
95 struct etharp_q_entry *q;
96 #else /* ARP_QUEUEING */
97 /** Pointer to a single pending outgoing packet on this ARP entry. */
98 struct pbuf *q;
99 #endif /* ARP_QUEUEING */
100 ip4_addr_t ipaddr;
101 struct netif *netif;
102 struct eth_addr ethaddr;
103 u16_t ctime;
104 u8_t state;
105 };
106  
107 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
108  
109 #if !LWIP_NETIF_HWADDRHINT
110 static u8_t etharp_cached_entry;
111 #endif /* !LWIP_NETIF_HWADDRHINT */
112  
113 /** Try hard to create a new entry - we want the IP address to appear in
114 the cache (even if this means removing an active entry or so). */
115 #define ETHARP_FLAG_TRY_HARD 1
116 #define ETHARP_FLAG_FIND_ONLY 2
117 #if ETHARP_SUPPORT_STATIC_ENTRIES
118 #define ETHARP_FLAG_STATIC_ENTRY 4
119 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
120  
121 #if LWIP_NETIF_HWADDRHINT
122 #define ETHARP_SET_ADDRHINT(netif, addrhint) do { if (((netif) != NULL) && ((netif)->hints != NULL)) { \
123 (netif)->hints->addr_hint = (addrhint); }} while(0)
124 #else /* LWIP_NETIF_HWADDRHINT */
125 #define ETHARP_SET_ADDRHINT(netif, addrhint) (etharp_cached_entry = (addrhint))
126 #endif /* LWIP_NETIF_HWADDRHINT */
127  
128  
129 /* Some checks, instead of etharp_init(): */
130 #if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
131 #error "ARP_TABLE_SIZE must fit in an s8_t, you have to reduce it in your lwipopts.h"
132 #endif
133  
134  
135 static err_t etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr);
136 static err_t etharp_raw(struct netif *netif,
137 const struct eth_addr *ethsrc_addr, const struct eth_addr *ethdst_addr,
138 const struct eth_addr *hwsrc_addr, const ip4_addr_t *ipsrc_addr,
139 const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr,
140 const u16_t opcode);
141  
142 #if ARP_QUEUEING
143 /**
144 * Free a complete queue of etharp entries
145 *
146 * @param q a qeueue of etharp_q_entry's to free
147 */
148 static void
149 free_etharp_q(struct etharp_q_entry *q)
150 {
151 struct etharp_q_entry *r;
152 LWIP_ASSERT("q != NULL", q != NULL);
153 LWIP_ASSERT("q->p != NULL", q->p != NULL);
154 while (q) {
155 r = q;
156 q = q->next;
157 LWIP_ASSERT("r->p != NULL", (r->p != NULL));
158 pbuf_free(r->p);
159 memp_free(MEMP_ARP_QUEUE, r);
160 }
161 }
162 #else /* ARP_QUEUEING */
163  
164 /** Compatibility define: free the queued pbuf */
165 #define free_etharp_q(q) pbuf_free(q)
166  
167 #endif /* ARP_QUEUEING */
168  
169 /** Clean up ARP table entries */
170 static void
171 etharp_free_entry(int i)
172 {
173 /* remove from SNMP ARP index tree */
174 mib2_remove_arp_entry(arp_table[i].netif, &arp_table[i].ipaddr);
175 /* and empty packet queue */
176 if (arp_table[i].q != NULL) {
177 /* remove all queued packets */
178 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_free_entry: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
179 free_etharp_q(arp_table[i].q);
180 arp_table[i].q = NULL;
181 }
182 /* recycle entry for re-use */
183 arp_table[i].state = ETHARP_STATE_EMPTY;
184 #ifdef LWIP_DEBUG
185 /* for debugging, clean out the complete entry */
186 arp_table[i].ctime = 0;
187 arp_table[i].netif = NULL;
188 ip4_addr_set_zero(&arp_table[i].ipaddr);
189 arp_table[i].ethaddr = ethzero;
190 #endif /* LWIP_DEBUG */
191 }
192  
193 /**
194 * Clears expired entries in the ARP table.
195 *
196 * This function should be called every ARP_TMR_INTERVAL milliseconds (1 second),
197 * in order to expire entries in the ARP table.
198 */
199 void
200 etharp_tmr(void)
201 {
202 u8_t i;
203  
204 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
205 /* remove expired entries from the ARP table */
206 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
207 u8_t state = arp_table[i].state;
208 if (state != ETHARP_STATE_EMPTY
209 #if ETHARP_SUPPORT_STATIC_ENTRIES
210 && (state != ETHARP_STATE_STATIC)
211 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
212 ) {
213 arp_table[i].ctime++;
214 if ((arp_table[i].ctime >= ARP_MAXAGE) ||
215 ((arp_table[i].state == ETHARP_STATE_PENDING) &&
216 (arp_table[i].ctime >= ARP_MAXPENDING))) {
217 /* pending or stable entry has become old! */
218 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
219 arp_table[i].state >= ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
220 /* clean up entries that have just been expired */
221 etharp_free_entry(i);
222 } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_1) {
223 /* Don't send more than one request every 2 seconds. */
224 arp_table[i].state = ETHARP_STATE_STABLE_REREQUESTING_2;
225 } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_2) {
226 /* Reset state to stable, so that the next transmitted packet will
227 re-send an ARP request. */
228 arp_table[i].state = ETHARP_STATE_STABLE;
229 } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
230 /* still pending, resend an ARP query */
231 etharp_request(arp_table[i].netif, &arp_table[i].ipaddr);
232 }
233 }
234 }
235 }
236  
237 /**
238 * Search the ARP table for a matching or new entry.
239 *
240 * If an IP address is given, return a pending or stable ARP entry that matches
241 * the address. If no match is found, create a new entry with this address set,
242 * but in state ETHARP_EMPTY. The caller must check and possibly change the
243 * state of the returned entry.
244 *
245 * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
246 *
247 * In all cases, attempt to create new entries from an empty entry. If no
248 * empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle
249 * old entries. Heuristic choose the least important entry for recycling.
250 *
251 * @param ipaddr IP address to find in ARP cache, or to add if not found.
252 * @param flags See @ref etharp_state
253 * @param netif netif related to this address (used for NETIF_HWADDRHINT)
254 *
255 * @return The ARP entry index that matched or is created, ERR_MEM if no
256 * entry is found or could be recycled.
257 */
258 static s8_t
259 etharp_find_entry(const ip4_addr_t *ipaddr, u8_t flags, struct netif *netif)
260 {
261 s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
262 s8_t empty = ARP_TABLE_SIZE;
263 u8_t i = 0;
264 /* oldest entry with packets on queue */
265 s8_t old_queue = ARP_TABLE_SIZE;
266 /* its age */
267 u16_t age_queue = 0, age_pending = 0, age_stable = 0;
268  
269 LWIP_UNUSED_ARG(netif);
270  
271 /**
272 * a) do a search through the cache, remember candidates
273 * b) select candidate entry
274 * c) create new entry
275 */
276  
277 /* a) in a single search sweep, do all of this
278 * 1) remember the first empty entry (if any)
279 * 2) remember the oldest stable entry (if any)
280 * 3) remember the oldest pending entry without queued packets (if any)
281 * 4) remember the oldest pending entry with queued packets (if any)
282 * 5) search for a matching IP entry, either pending or stable
283 * until 5 matches, or all entries are searched for.
284 */
285  
286 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
287 u8_t state = arp_table[i].state;
288 /* no empty entry found yet and now we do find one? */
289 if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) {
290 LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_find_entry: found empty entry %"U16_F"\n", (u16_t)i));
291 /* remember first empty entry */
292 empty = (s8_t)i;
293 } else if (state != ETHARP_STATE_EMPTY) {
294 LWIP_ASSERT("state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE",
295 state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE);
296 /* if given, does IP address match IP address in ARP entry? */
297 if (ipaddr && ip4_addr_cmp(ipaddr, &arp_table[i].ipaddr)
298 #if ETHARP_TABLE_MATCH_NETIF
299 && ((netif == NULL) || (netif == arp_table[i].netif))
300 #endif /* ETHARP_TABLE_MATCH_NETIF */
301 ) {
302 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: found matching entry %"U16_F"\n", (u16_t)i));
303 /* found exact IP address match, simply bail out */
304 return (s8_t)i;
305 }
306 /* pending entry? */
307 if (state == ETHARP_STATE_PENDING) {
308 /* pending with queued packets? */
309 if (arp_table[i].q != NULL) {
310 if (arp_table[i].ctime >= age_queue) {
311 old_queue = (s8_t)i;
312 age_queue = arp_table[i].ctime;
313 }
314 } else
315 /* pending without queued packets? */
316 {
317 if (arp_table[i].ctime >= age_pending) {
318 old_pending = (s8_t)i;
319 age_pending = arp_table[i].ctime;
320 }
321 }
322 /* stable entry? */
323 } else if (state >= ETHARP_STATE_STABLE) {
324 #if ETHARP_SUPPORT_STATIC_ENTRIES
325 /* don't record old_stable for static entries since they never expire */
326 if (state < ETHARP_STATE_STATIC)
327 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
328 {
329 /* remember entry with oldest stable entry in oldest, its age in maxtime */
330 if (arp_table[i].ctime >= age_stable) {
331 old_stable = (s8_t)i;
332 age_stable = arp_table[i].ctime;
333 }
334 }
335 }
336 }
337 }
338 /* { we have no match } => try to create a new entry */
339  
340 /* don't create new entry, only search? */
341 if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) ||
342 /* or no empty entry found and not allowed to recycle? */
343 ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) {
344 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty entry found and not allowed to recycle\n"));
345 return (s8_t)ERR_MEM;
346 }
347  
348 /* b) choose the least destructive entry to recycle:
349 * 1) empty entry
350 * 2) oldest stable entry
351 * 3) oldest pending entry without queued packets
352 * 4) oldest pending entry with queued packets
353 *
354 * { ETHARP_FLAG_TRY_HARD is set at this point }
355 */
356  
357 /* 1) empty entry available? */
358 if (empty < ARP_TABLE_SIZE) {
359 i = (u8_t)empty;
360 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
361 } else {
362 /* 2) found recyclable stable entry? */
363 if (old_stable < ARP_TABLE_SIZE) {
364 /* recycle oldest stable*/
365 i = (u8_t)old_stable;
366 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
367 /* no queued packets should exist on stable entries */
368 LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
369 /* 3) found recyclable pending entry without queued packets? */
370 } else if (old_pending < ARP_TABLE_SIZE) {
371 /* recycle oldest pending */
372 i = (u8_t)old_pending;
373 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
374 /* 4) found recyclable pending entry with queued packets? */
375 } else if (old_queue < ARP_TABLE_SIZE) {
376 /* recycle oldest pending (queued packets are free in etharp_free_entry) */
377 i = (u8_t)old_queue;
378 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].q)));
379 /* no empty or recyclable entries found */
380 } else {
381 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty or recyclable entries found\n"));
382 return (s8_t)ERR_MEM;
383 }
384  
385 /* { empty or recyclable entry found } */
386 LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
387 etharp_free_entry(i);
388 }
389  
390 LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
391 LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY",
392 arp_table[i].state == ETHARP_STATE_EMPTY);
393  
394 /* IP address given? */
395 if (ipaddr != NULL) {
396 /* set IP address */
397 ip4_addr_copy(arp_table[i].ipaddr, *ipaddr);
398 }
399 arp_table[i].ctime = 0;
400 #if ETHARP_TABLE_MATCH_NETIF
401 arp_table[i].netif = netif;
402 #endif /* ETHARP_TABLE_MATCH_NETIF*/
403 return (err_t)i;
404 }
405  
406 /**
407 * Update (or insert) a IP/MAC address pair in the ARP cache.
408 *
409 * If a pending entry is resolved, any queued packets will be sent
410 * at this point.
411 *
412 * @param netif netif related to this entry (used for NETIF_ADDRHINT)
413 * @param ipaddr IP address of the inserted ARP entry.
414 * @param ethaddr Ethernet address of the inserted ARP entry.
415 * @param flags See @ref etharp_state
416 *
417 * @return
418 * - ERR_OK Successfully updated ARP cache.
419 * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
420 * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
421 *
422 * @see pbuf_free()
423 */
424 static err_t
425 etharp_update_arp_entry(struct netif *netif, const ip4_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
426 {
427 s8_t i;
428 LWIP_ASSERT("netif->hwaddr_len == ETH_HWADDR_LEN", netif->hwaddr_len == ETH_HWADDR_LEN);
429 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",
430 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
431 (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2],
432 (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5]));
433 /* non-unicast address? */
434 if (ip4_addr_isany(ipaddr) ||
435 ip4_addr_isbroadcast(ipaddr, netif) ||
436 ip4_addr_ismulticast(ipaddr)) {
437 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
438 return ERR_ARG;
439 }
440 /* find or create ARP entry */
441 i = etharp_find_entry(ipaddr, flags, netif);
442 /* bail out if no entry could be found */
443 if (i < 0) {
444 return (err_t)i;
445 }
446  
447 #if ETHARP_SUPPORT_STATIC_ENTRIES
448 if (flags & ETHARP_FLAG_STATIC_ENTRY) {
449 /* record static type */
450 arp_table[i].state = ETHARP_STATE_STATIC;
451 } else if (arp_table[i].state == ETHARP_STATE_STATIC) {
452 /* found entry is a static type, don't overwrite it */
453 return ERR_VAL;
454 } else
455 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
456 {
457 /* mark it stable */
458 arp_table[i].state = ETHARP_STATE_STABLE;
459 }
460  
461 /* record network interface */
462 arp_table[i].netif = netif;
463 /* insert in SNMP ARP index tree */
464 mib2_add_arp_entry(netif, &arp_table[i].ipaddr);
465  
466 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
467 /* update address */
468 SMEMCPY(&arp_table[i].ethaddr, ethaddr, ETH_HWADDR_LEN);
469 /* reset time stamp */
470 arp_table[i].ctime = 0;
471 /* this is where we will send out queued packets! */
472 #if ARP_QUEUEING
473 while (arp_table[i].q != NULL) {
474 struct pbuf *p;
475 /* remember remainder of queue */
476 struct etharp_q_entry *q = arp_table[i].q;
477 /* pop first item off the queue */
478 arp_table[i].q = q->next;
479 /* get the packet pointer */
480 p = q->p;
481 /* now queue entry can be freed */
482 memp_free(MEMP_ARP_QUEUE, q);
483 #else /* ARP_QUEUEING */
484 if (arp_table[i].q != NULL) {
485 struct pbuf *p = arp_table[i].q;
486 arp_table[i].q = NULL;
487 #endif /* ARP_QUEUEING */
488 /* send the queued IP packet */
489 ethernet_output(netif, p, (struct eth_addr *)(netif->hwaddr), ethaddr, ETHTYPE_IP);
490 /* free the queued IP packet */
491 pbuf_free(p);
492 }
493 return ERR_OK;
494 }
495  
496 #if ETHARP_SUPPORT_STATIC_ENTRIES
497 /** Add a new static entry to the ARP table. If an entry exists for the
498 * specified IP address, this entry is overwritten.
499 * If packets are queued for the specified IP address, they are sent out.
500 *
501 * @param ipaddr IP address for the new static entry
502 * @param ethaddr ethernet address for the new static entry
503 * @return See return values of etharp_add_static_entry
504 */
505 err_t
506 etharp_add_static_entry(const ip4_addr_t *ipaddr, struct eth_addr *ethaddr)
507 {
508 struct netif *netif;
509 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",
510 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
511 (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2],
512 (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5]));
513  
514 netif = ip4_route(ipaddr);
515 if (netif == NULL) {
516 return ERR_RTE;
517 }
518  
519 return etharp_update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY);
520 }
521  
522 /** Remove a static entry from the ARP table previously added with a call to
523 * etharp_add_static_entry.
524 *
525 * @param ipaddr IP address of the static entry to remove
526 * @return ERR_OK: entry removed
527 * ERR_MEM: entry wasn't found
528 * ERR_ARG: entry wasn't a static entry but a dynamic one
529 */
530 err_t
531 etharp_remove_static_entry(const ip4_addr_t *ipaddr)
532 {
533 s8_t i;
534 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
535 ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
536  
537 /* find or create ARP entry */
538 i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, NULL);
539 /* bail out if no entry could be found */
540 if (i < 0) {
541 return (err_t)i;
542 }
543  
544 if (arp_table[i].state != ETHARP_STATE_STATIC) {
545 /* entry wasn't a static entry, cannot remove it */
546 return ERR_ARG;
547 }
548 /* entry found, free it */
549 etharp_free_entry(i);
550 return ERR_OK;
551 }
552 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
553  
554 /**
555 * Remove all ARP table entries of the specified netif.
556 *
557 * @param netif points to a network interface
558 */
559 void
560 etharp_cleanup_netif(struct netif *netif)
561 {
562 u8_t i;
563  
564 for (i = 0; i < ARP_TABLE_SIZE; ++i) {
565 u8_t state = arp_table[i].state;
566 if ((state != ETHARP_STATE_EMPTY) && (arp_table[i].netif == netif)) {
567 etharp_free_entry(i);
568 }
569 }
570 }
571  
572 /**
573 * Finds (stable) ethernet/IP address pair from ARP table
574 * using interface and IP address index.
575 * @note the addresses in the ARP table are in network order!
576 *
577 * @param netif points to interface index
578 * @param ipaddr points to the (network order) IP address index
579 * @param eth_ret points to return pointer
580 * @param ip_ret points to return pointer
581 * @return table index if found, -1 otherwise
582 */
583 s8_t
584 etharp_find_addr(struct netif *netif, const ip4_addr_t *ipaddr,
585 struct eth_addr **eth_ret, const ip4_addr_t **ip_ret)
586 {
587 s8_t i;
588  
589 LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL",
590 eth_ret != NULL && ip_ret != NULL);
591  
592 LWIP_UNUSED_ARG(netif);
593  
594 i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, netif);
595 if ((i >= 0) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
596 *eth_ret = &arp_table[i].ethaddr;
597 *ip_ret = &arp_table[i].ipaddr;
598 return i;
599 }
600 return -1;
601 }
602  
603 /**
604 * Possibility to iterate over stable ARP table entries
605 *
606 * @param i entry number, 0 to ARP_TABLE_SIZE
607 * @param ipaddr return value: IP address
608 * @param netif return value: points to interface
609 * @param eth_ret return value: ETH address
610 * @return 1 on valid index, 0 otherwise
611 */
612 u8_t
613 etharp_get_entry(u8_t i, ip4_addr_t **ipaddr, struct netif **netif, struct eth_addr **eth_ret)
614 {
615 LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
616 LWIP_ASSERT("netif != NULL", netif != NULL);
617 LWIP_ASSERT("eth_ret != NULL", eth_ret != NULL);
618  
619 if ((i < ARP_TABLE_SIZE) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
620 *ipaddr = &arp_table[i].ipaddr;
621 *netif = arp_table[i].netif;
622 *eth_ret = &arp_table[i].ethaddr;
623 return 1;
624 } else {
625 return 0;
626 }
627 }
628  
629 /**
630 * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache
631 * send out queued IP packets. Updates cache with snooped address pairs.
632 *
633 * Should be called for incoming ARP packets. The pbuf in the argument
634 * is freed by this function.
635 *
636 * @param p The ARP packet that arrived on netif. Is freed by this function.
637 * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
638 *
639 * @see pbuf_free()
640 */
641 void
642 etharp_input(struct pbuf *p, struct netif *netif)
643 {
644 struct etharp_hdr *hdr;
645 /* these are aligned properly, whereas the ARP header fields might not be */
646 ip4_addr_t sipaddr, dipaddr;
647 u8_t for_us;
648  
649 LWIP_ERROR("netif != NULL", (netif != NULL), return;);
650  
651 hdr = (struct etharp_hdr *)p->payload;
652  
653 /* RFC 826 "Packet Reception": */
654 if ((hdr->hwtype != PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET)) ||
655 (hdr->hwlen != ETH_HWADDR_LEN) ||
656 (hdr->protolen != sizeof(ip4_addr_t)) ||
657 (hdr->proto != PP_HTONS(ETHTYPE_IP))) {
658 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
659 ("etharp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
660 hdr->hwtype, (u16_t)hdr->hwlen, hdr->proto, (u16_t)hdr->protolen));
661 ETHARP_STATS_INC(etharp.proterr);
662 ETHARP_STATS_INC(etharp.drop);
663 pbuf_free(p);
664 return;
665 }
666 ETHARP_STATS_INC(etharp.recv);
667  
668 #if LWIP_AUTOIP
669 /* We have to check if a host already has configured our random
670 * created link local address and continuously check if there is
671 * a host with this IP-address so we can detect collisions */
672 autoip_arp_reply(netif, hdr);
673 #endif /* LWIP_AUTOIP */
674  
675 /* Copy struct ip4_addr_wordaligned to aligned ip4_addr, to support compilers without
676 * structure packing (not using structure copy which breaks strict-aliasing rules). */
677 IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&sipaddr, &hdr->sipaddr);
678 IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&dipaddr, &hdr->dipaddr);
679  
680 /* this interface is not configured? */
681 if (ip4_addr_isany_val(*netif_ip4_addr(netif))) {
682 for_us = 0;
683 } else {
684 /* ARP packet directed to us? */
685 for_us = (u8_t)ip4_addr_cmp(&dipaddr, netif_ip4_addr(netif));
686 }
687  
688 /* ARP message directed to us?
689 -> add IP address in ARP cache; assume requester wants to talk to us,
690 can result in directly sending the queued packets for this host.
691 ARP message not directed to us?
692 -> update the source IP address in the cache, if present */
693 etharp_update_arp_entry(netif, &sipaddr, &(hdr->shwaddr),
694 for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
695  
696 /* now act on the message itself */
697 switch (hdr->opcode) {
698 /* ARP request? */
699 case PP_HTONS(ARP_REQUEST):
700 /* ARP request. If it asked for our address, we send out a
701 * reply. In any case, we time-stamp any existing ARP entry,
702 * and possibly send out an IP packet that was queued on it. */
703  
704 LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: incoming ARP request\n"));
705 /* ARP request for our address? */
706 if (for_us) {
707 /* send ARP response */
708 etharp_raw(netif,
709 (struct eth_addr *)netif->hwaddr, &hdr->shwaddr,
710 (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif),
711 &hdr->shwaddr, &sipaddr,
712 ARP_REPLY);
713 /* we are not configured? */
714 } else if (ip4_addr_isany_val(*netif_ip4_addr(netif))) {
715 /* { for_us == 0 and netif->ip_addr.addr == 0 } */
716 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: we are unconfigured, ARP request ignored.\n"));
717 /* request was not directed to us */
718 } else {
719 /* { for_us == 0 and netif->ip_addr.addr != 0 } */
720 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: ARP request was not for us.\n"));
721 }
722 break;
723 case PP_HTONS(ARP_REPLY):
724 /* ARP reply. We already updated the ARP cache earlier. */
725 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: incoming ARP reply\n"));
726 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
727 /* DHCP wants to know about ARP replies from any host with an
728 * IP address also offered to us by the DHCP server. We do not
729 * want to take a duplicate IP address on a single network.
730 * @todo How should we handle redundant (fail-over) interfaces? */
731 dhcp_arp_reply(netif, &sipaddr);
732 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
733 break;
734 default:
735 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: ARP unknown opcode type %"S16_F"\n", lwip_htons(hdr->opcode)));
736 ETHARP_STATS_INC(etharp.err);
737 break;
738 }
739 /* free ARP packet */
740 pbuf_free(p);
741 }
742  
743 /** Just a small helper function that sends a pbuf to an ethernet address
744 * in the arp_table specified by the index 'arp_idx'.
745 */
746 static err_t
747 etharp_output_to_arp_index(struct netif *netif, struct pbuf *q, u8_t arp_idx)
748 {
749 LWIP_ASSERT("arp_table[arp_idx].state >= ETHARP_STATE_STABLE",
750 arp_table[arp_idx].state >= ETHARP_STATE_STABLE);
751 /* if arp table entry is about to expire: re-request it,
752 but only if its state is ETHARP_STATE_STABLE to prevent flooding the
753 network with ARP requests if this address is used frequently. */
754 if (arp_table[arp_idx].state == ETHARP_STATE_STABLE) {
755 if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_BROADCAST) {
756 /* issue a standard request using broadcast */
757 if (etharp_request(netif, &arp_table[arp_idx].ipaddr) == ERR_OK) {
758 arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1;
759 }
760 } else if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_UNICAST) {
761 /* issue a unicast request (for 15 seconds) to prevent unnecessary broadcast */
762 if (etharp_request_dst(netif, &arp_table[arp_idx].ipaddr, &arp_table[arp_idx].ethaddr) == ERR_OK) {
763 arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1;
764 }
765 }
766 }
767  
768 return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), &arp_table[arp_idx].ethaddr, ETHTYPE_IP);
769 }
770  
771 /**
772 * Resolve and fill-in Ethernet address header for outgoing IP packet.
773 *
774 * For IP multicast and broadcast, corresponding Ethernet addresses
775 * are selected and the packet is transmitted on the link.
776 *
777 * For unicast addresses, the packet is submitted to etharp_query(). In
778 * case the IP address is outside the local network, the IP address of
779 * the gateway is used.
780 *
781 * @param netif The lwIP network interface which the IP packet will be sent on.
782 * @param q The pbuf(s) containing the IP packet to be sent.
783 * @param ipaddr The IP address of the packet destination.
784 *
785 * @return
786 * - ERR_RTE No route to destination (no gateway to external networks),
787 * or the return type of either etharp_query() or ethernet_output().
788 */
789 err_t
790 etharp_output(struct netif *netif, struct pbuf *q, const ip4_addr_t *ipaddr)
791 {
792 const struct eth_addr *dest;
793 struct eth_addr mcastaddr;
794 const ip4_addr_t *dst_addr = ipaddr;
795  
796 LWIP_ASSERT("netif != NULL", netif != NULL);
797 LWIP_ASSERT("q != NULL", q != NULL);
798 LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
799  
800 /* Determine on destination hardware address. Broadcasts and multicasts
801 * are special, other IP addresses are looked up in the ARP table. */
802  
803 /* broadcast destination IP address? */
804 if (ip4_addr_isbroadcast(ipaddr, netif)) {
805 /* broadcast on Ethernet also */
806 dest = (const struct eth_addr *)&ethbroadcast;
807 /* multicast destination IP address? */
808 } else if (ip4_addr_ismulticast(ipaddr)) {
809 /* Hash IP multicast address to MAC address.*/
810 mcastaddr.addr[0] = LL_IP4_MULTICAST_ADDR_0;
811 mcastaddr.addr[1] = LL_IP4_MULTICAST_ADDR_1;
812 mcastaddr.addr[2] = LL_IP4_MULTICAST_ADDR_2;
813 mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
814 mcastaddr.addr[4] = ip4_addr3(ipaddr);
815 mcastaddr.addr[5] = ip4_addr4(ipaddr);
816 /* destination Ethernet address is multicast */
817 dest = &mcastaddr;
818 /* unicast destination IP address? */
819 } else {
820 u8_t i;
821 /* outside local network? if so, this can neither be a global broadcast nor
822 a subnet broadcast. */
823 if (!ip4_addr_netcmp(ipaddr, netif_ip4_addr(netif), netif_ip4_netmask(netif)) &&
824 !ip4_addr_islinklocal(ipaddr)) {
825 #if LWIP_AUTOIP
826 struct ip_hdr *iphdr = LWIP_ALIGNMENT_CAST(struct ip_hdr *, q->payload);
827 /* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with
828 a link-local source address must always be "directly to its destination
829 on the same physical link. The host MUST NOT send the packet to any
830 router for forwarding". */
831 if (!ip4_addr_islinklocal(&iphdr->src))
832 #endif /* LWIP_AUTOIP */
833 {
834 #ifdef LWIP_HOOK_ETHARP_GET_GW
835 /* For advanced routing, a single default gateway might not be enough, so get
836 the IP address of the gateway to handle the current destination address. */
837 dst_addr = LWIP_HOOK_ETHARP_GET_GW(netif, ipaddr);
838 if (dst_addr == NULL)
839 #endif /* LWIP_HOOK_ETHARP_GET_GW */
840 {
841 /* interface has default gateway? */
842 if (!ip4_addr_isany_val(*netif_ip4_gw(netif))) {
843 /* send to hardware address of default gateway IP address */
844 dst_addr = netif_ip4_gw(netif);
845 /* no default gateway available */
846 } else {
847 /* no route to destination error (default gateway missing) */
848 return ERR_RTE;
849 }
850 }
851 }
852 }
853 #if LWIP_NETIF_HWADDRHINT
854 if (netif->hints != NULL) {
855 /* per-pcb cached entry was given */
856 u8_t etharp_cached_entry = netif->hints->addr_hint;
857 if (etharp_cached_entry < ARP_TABLE_SIZE) {
858 #endif /* LWIP_NETIF_HWADDRHINT */
859 if ((arp_table[etharp_cached_entry].state >= ETHARP_STATE_STABLE) &&
860 #if ETHARP_TABLE_MATCH_NETIF
861 (arp_table[etharp_cached_entry].netif == netif) &&
862 #endif
863 (ip4_addr_cmp(dst_addr, &arp_table[etharp_cached_entry].ipaddr))) {
864 /* the per-pcb-cached entry is stable and the right one! */
865 ETHARP_STATS_INC(etharp.cachehit);
866 return etharp_output_to_arp_index(netif, q, etharp_cached_entry);
867 }
868 #if LWIP_NETIF_HWADDRHINT
869 }
870 }
871 #endif /* LWIP_NETIF_HWADDRHINT */
872  
873 /* find stable entry: do this here since this is a critical path for
874 throughput and etharp_find_entry() is kind of slow */
875 for (i = 0; i < ARP_TABLE_SIZE; i++) {
876 if ((arp_table[i].state >= ETHARP_STATE_STABLE) &&
877 #if ETHARP_TABLE_MATCH_NETIF
878 (arp_table[i].netif == netif) &&
879 #endif
880 (ip4_addr_cmp(dst_addr, &arp_table[i].ipaddr))) {
881 /* found an existing, stable entry */
882 ETHARP_SET_ADDRHINT(netif, i);
883 return etharp_output_to_arp_index(netif, q, i);
884 }
885 }
886 /* no stable entry found, use the (slower) query function:
887 queue on destination Ethernet address belonging to ipaddr */
888 return etharp_query(netif, dst_addr, q);
889 }
890  
891 /* continuation for multicast/broadcast destinations */
892 /* obtain source Ethernet address of the given interface */
893 /* send packet directly on the link */
894 return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), dest, ETHTYPE_IP);
895 }
896  
897 /**
898 * Send an ARP request for the given IP address and/or queue a packet.
899 *
900 * If the IP address was not yet in the cache, a pending ARP cache entry
901 * is added and an ARP request is sent for the given address. The packet
902 * is queued on this entry.
903 *
904 * If the IP address was already pending in the cache, a new ARP request
905 * is sent for the given address. The packet is queued on this entry.
906 *
907 * If the IP address was already stable in the cache, and a packet is
908 * given, it is directly sent and no ARP request is sent out.
909 *
910 * If the IP address was already stable in the cache, and no packet is
911 * given, an ARP request is sent out.
912 *
913 * @param netif The lwIP network interface on which ipaddr
914 * must be queried for.
915 * @param ipaddr The IP address to be resolved.
916 * @param q If non-NULL, a pbuf that must be delivered to the IP address.
917 * q is not freed by this function.
918 *
919 * @note q must only be ONE packet, not a packet queue!
920 *
921 * @return
922 * - ERR_BUF Could not make room for Ethernet header.
923 * - ERR_MEM Hardware address unknown, and no more ARP entries available
924 * to query for address or queue the packet.
925 * - ERR_MEM Could not queue packet due to memory shortage.
926 * - ERR_RTE No route to destination (no gateway to external networks).
927 * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
928 *
929 */
930 err_t
931 etharp_query(struct netif *netif, const ip4_addr_t *ipaddr, struct pbuf *q)
932 {
933 struct eth_addr *srcaddr = (struct eth_addr *)netif->hwaddr;
934 err_t result = ERR_MEM;
935 int is_new_entry = 0;
936 s8_t i_err;
937 u8_t i;
938  
939 /* non-unicast address? */
940 if (ip4_addr_isbroadcast(ipaddr, netif) ||
941 ip4_addr_ismulticast(ipaddr) ||
942 ip4_addr_isany(ipaddr)) {
943 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
944 return ERR_ARG;
945 }
946  
947 /* find entry in ARP cache, ask to create entry if queueing packet */
948 i_err = etharp_find_entry(ipaddr, ETHARP_FLAG_TRY_HARD, netif);
949  
950 /* could not find or create entry? */
951 if (i_err < 0) {
952 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
953 if (q) {
954 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
955 ETHARP_STATS_INC(etharp.memerr);
956 }
957 return (err_t)i_err;
958 }
959 i = (u8_t)i_err;
960  
961 /* mark a fresh entry as pending (we just sent a request) */
962 if (arp_table[i].state == ETHARP_STATE_EMPTY) {
963 is_new_entry = 1;
964 arp_table[i].state = ETHARP_STATE_PENDING;
965 /* record network interface for re-sending arp request in etharp_tmr */
966 arp_table[i].netif = netif;
967 }
968  
969 /* { i is either a STABLE or (new or existing) PENDING entry } */
970 LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
971 ((arp_table[i].state == ETHARP_STATE_PENDING) ||
972 (arp_table[i].state >= ETHARP_STATE_STABLE)));
973  
974 /* do we have a new entry? or an implicit query request? */
975 if (is_new_entry || (q == NULL)) {
976 /* try to resolve it; send out ARP request */
977 result = etharp_request(netif, ipaddr);
978 if (result != ERR_OK) {
979 /* ARP request couldn't be sent */
980 /* We don't re-send arp request in etharp_tmr, but we still queue packets,
981 since this failure could be temporary, and the next packet calling
982 etharp_query again could lead to sending the queued packets. */
983 }
984 if (q == NULL) {
985 return result;
986 }
987 }
988  
989 /* packet given? */
990 LWIP_ASSERT("q != NULL", q != NULL);
991 /* stable entry? */
992 if (arp_table[i].state >= ETHARP_STATE_STABLE) {
993 /* we have a valid IP->Ethernet address mapping */
994 ETHARP_SET_ADDRHINT(netif, i);
995 /* send the packet */
996 result = ethernet_output(netif, q, srcaddr, &(arp_table[i].ethaddr), ETHTYPE_IP);
997 /* pending entry? (either just created or already pending */
998 } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
999 /* entry is still pending, queue the given packet 'q' */
1000 struct pbuf *p;
1001 int copy_needed = 0;
1002 /* IF q includes a pbuf that must be copied, copy the whole chain into a
1003 * new PBUF_RAM. See the definition of PBUF_NEEDS_COPY for details. */
1004 p = q;
1005 while (p) {
1006 LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
1007 if (PBUF_NEEDS_COPY(p)) {
1008 copy_needed = 1;
1009 break;
1010 }
1011 p = p->next;
1012 }
1013 if (copy_needed) {
1014 /* copy the whole packet into new pbufs */
1015 p = pbuf_alloc(PBUF_LINK, q->tot_len, PBUF_RAM);
1016 if (p != NULL) {
1017 if (pbuf_copy(p, q) != ERR_OK) {
1018 pbuf_free(p);
1019 p = NULL;
1020 }
1021 }
1022 } else {
1023 /* referencing the old pbuf is enough */
1024 p = q;
1025 pbuf_ref(p);
1026 }
1027 /* packet could be taken over? */
1028 if (p != NULL) {
1029 /* queue packet ... */
1030 #if ARP_QUEUEING
1031 struct etharp_q_entry *new_entry;
1032 /* allocate a new arp queue entry */
1033 new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
1034 if (new_entry != NULL) {
1035 unsigned int qlen = 0;
1036 new_entry->next = 0;
1037 new_entry->p = p;
1038 if (arp_table[i].q != NULL) {
1039 /* queue was already existent, append the new entry to the end */
1040 struct etharp_q_entry *r;
1041 r = arp_table[i].q;
1042 qlen++;
1043 while (r->next != NULL) {
1044 r = r->next;
1045 qlen++;
1046 }
1047 r->next = new_entry;
1048 } else {
1049 /* queue did not exist, first item in queue */
1050 arp_table[i].q = new_entry;
1051 }
1052 #if ARP_QUEUE_LEN
1053 if (qlen >= ARP_QUEUE_LEN) {
1054 struct etharp_q_entry *old;
1055 old = arp_table[i].q;
1056 arp_table[i].q = arp_table[i].q->next;
1057 pbuf_free(old->p);
1058 memp_free(MEMP_ARP_QUEUE, old);
1059 }
1060 #endif
1061 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
1062 result = ERR_OK;
1063 } else {
1064 /* the pool MEMP_ARP_QUEUE is empty */
1065 pbuf_free(p);
1066 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));
1067 result = ERR_MEM;
1068 }
1069 #else /* ARP_QUEUEING */
1070 /* always queue one packet per ARP request only, freeing a previously queued packet */
1071 if (arp_table[i].q != NULL) {
1072 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: dropped previously queued packet %p for ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
1073 pbuf_free(arp_table[i].q);
1074 }
1075 arp_table[i].q = p;
1076 result = ERR_OK;
1077 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
1078 #endif /* ARP_QUEUEING */
1079 } else {
1080 ETHARP_STATS_INC(etharp.memerr);
1081 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));
1082 result = ERR_MEM;
1083 }
1084 }
1085 return result;
1086 }
1087  
1088 /**
1089 * Send a raw ARP packet (opcode and all addresses can be modified)
1090 *
1091 * @param netif the lwip network interface on which to send the ARP packet
1092 * @param ethsrc_addr the source MAC address for the ethernet header
1093 * @param ethdst_addr the destination MAC address for the ethernet header
1094 * @param hwsrc_addr the source MAC address for the ARP protocol header
1095 * @param ipsrc_addr the source IP address for the ARP protocol header
1096 * @param hwdst_addr the destination MAC address for the ARP protocol header
1097 * @param ipdst_addr the destination IP address for the ARP protocol header
1098 * @param opcode the type of the ARP packet
1099 * @return ERR_OK if the ARP packet has been sent
1100 * ERR_MEM if the ARP packet couldn't be allocated
1101 * any other err_t on failure
1102 */
1103 static err_t
1104 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
1105 const struct eth_addr *ethdst_addr,
1106 const struct eth_addr *hwsrc_addr, const ip4_addr_t *ipsrc_addr,
1107 const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr,
1108 const u16_t opcode)
1109 {
1110 struct pbuf *p;
1111 err_t result = ERR_OK;
1112 struct etharp_hdr *hdr;
1113  
1114 LWIP_ASSERT("netif != NULL", netif != NULL);
1115  
1116 /* allocate a pbuf for the outgoing ARP request packet */
1117 p = pbuf_alloc(PBUF_LINK, SIZEOF_ETHARP_HDR, PBUF_RAM);
1118 /* could allocate a pbuf for an ARP request? */
1119 if (p == NULL) {
1120 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
1121 ("etharp_raw: could not allocate pbuf for ARP request.\n"));
1122 ETHARP_STATS_INC(etharp.memerr);
1123 return ERR_MEM;
1124 }
1125 LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
1126 (p->len >= SIZEOF_ETHARP_HDR));
1127  
1128 hdr = (struct etharp_hdr *)p->payload;
1129 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
1130 hdr->opcode = lwip_htons(opcode);
1131  
1132 LWIP_ASSERT("netif->hwaddr_len must be the same as ETH_HWADDR_LEN for etharp!",
1133 (netif->hwaddr_len == ETH_HWADDR_LEN));
1134  
1135 /* Write the ARP MAC-Addresses */
1136 SMEMCPY(&hdr->shwaddr, hwsrc_addr, ETH_HWADDR_LEN);
1137 SMEMCPY(&hdr->dhwaddr, hwdst_addr, ETH_HWADDR_LEN);
1138 /* Copy struct ip4_addr_wordaligned to aligned ip4_addr, to support compilers without
1139 * structure packing. */
1140 IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->sipaddr, ipsrc_addr);
1141 IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->dipaddr, ipdst_addr);
1142  
1143 hdr->hwtype = PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET);
1144 hdr->proto = PP_HTONS(ETHTYPE_IP);
1145 /* set hwlen and protolen */
1146 hdr->hwlen = ETH_HWADDR_LEN;
1147 hdr->protolen = sizeof(ip4_addr_t);
1148  
1149 /* send ARP query */
1150 #if LWIP_AUTOIP
1151 /* If we are using Link-Local, all ARP packets that contain a Link-Local
1152 * 'sender IP address' MUST be sent using link-layer broadcast instead of
1153 * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
1154 if (ip4_addr_islinklocal(ipsrc_addr)) {
1155 ethernet_output(netif, p, ethsrc_addr, &ethbroadcast, ETHTYPE_ARP);
1156 } else
1157 #endif /* LWIP_AUTOIP */
1158 {
1159 ethernet_output(netif, p, ethsrc_addr, ethdst_addr, ETHTYPE_ARP);
1160 }
1161  
1162 ETHARP_STATS_INC(etharp.xmit);
1163 /* free ARP query packet */
1164 pbuf_free(p);
1165 p = NULL;
1166 /* could not allocate pbuf for ARP request */
1167  
1168 return result;
1169 }
1170  
1171 /**
1172 * Send an ARP request packet asking for ipaddr to a specific eth address.
1173 * Used to send unicast request to refresh the ARP table just before an entry
1174 * times out
1175 *
1176 * @param netif the lwip network interface on which to send the request
1177 * @param ipaddr the IP address for which to ask
1178 * @param hw_dst_addr the ethernet address to send this packet to
1179 * @return ERR_OK if the request has been sent
1180 * ERR_MEM if the ARP packet couldn't be allocated
1181 * any other err_t on failure
1182 */
1183 static err_t
1184 etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr)
1185 {
1186 return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, hw_dst_addr,
1187 (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif), &ethzero,
1188 ipaddr, ARP_REQUEST);
1189 }
1190  
1191 /**
1192 * Send an ARP request packet asking for ipaddr.
1193 *
1194 * @param netif the lwip network interface on which to send the request
1195 * @param ipaddr the IP address for which to ask
1196 * @return ERR_OK if the request has been sent
1197 * ERR_MEM if the ARP packet couldn't be allocated
1198 * any other err_t on failure
1199 */
1200 err_t
1201 etharp_request(struct netif *netif, const ip4_addr_t *ipaddr)
1202 {
1203 LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
1204 return etharp_request_dst(netif, ipaddr, &ethbroadcast);
1205 }
1206 #endif /* LWIP_IPV4 && LWIP_ARP */
1207  
1208 #endif /* LWIP_ARP || LWIP_ETHERNET */