cxgb4i : remove spurious use of rcu
[linux-2.6-block.git] / net / batman-adv / distributed-arp-table.c
CommitLineData
e19f9759 1/* Copyright (C) 2011-2014 B.A.T.M.A.N. contributors:
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2 *
3 * Antonio Quartulli
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of version 2 of the GNU General Public
7 * License as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
ebf38fb7 15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
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16 */
17
18#include <linux/if_ether.h>
19#include <linux/if_arp.h>
be1db4f6 20#include <linux/if_vlan.h>
c384ea3e 21#include <net/arp.h>
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22
23#include "main.h"
5c3a0e55 24#include "hash.h"
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25#include "distributed-arp-table.h"
26#include "hard-interface.h"
27#include "originator.h"
28#include "send.h"
29#include "types.h"
c384ea3e 30#include "translation-table.h"
785ea114 31
2f1dfbe1
AQ
32static void batadv_dat_purge(struct work_struct *work);
33
34/**
35 * batadv_dat_start_timer - initialise the DAT periodic worker
36 * @bat_priv: the bat priv with all the soft interface information
37 */
38static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
39{
40 INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
41 queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
42 msecs_to_jiffies(10000));
43}
44
45/**
93178018 46 * batadv_dat_entry_free_ref - decrement the dat_entry refcounter and possibly
2f1dfbe1 47 * free it
93178018 48 * @dat_entry: the entry to free
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49 */
50static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
51{
52 if (atomic_dec_and_test(&dat_entry->refcount))
53 kfree_rcu(dat_entry, rcu);
54}
55
56/**
93178018 57 * batadv_dat_to_purge - check whether a dat_entry has to be purged or not
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58 * @dat_entry: the entry to check
59 *
93178018 60 * Returns true if the entry has to be purged now, false otherwise.
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61 */
62static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
63{
64 return batadv_has_timed_out(dat_entry->last_update,
65 BATADV_DAT_ENTRY_TIMEOUT);
66}
67
68/**
69 * __batadv_dat_purge - delete entries from the DAT local storage
70 * @bat_priv: the bat priv with all the soft interface information
71 * @to_purge: function in charge to decide whether an entry has to be purged or
72 * not. This function takes the dat_entry as argument and has to
73 * returns a boolean value: true is the entry has to be deleted,
74 * false otherwise
75 *
93178018
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76 * Loops over each entry in the DAT local storage and deletes it if and only if
77 * the to_purge function passed as argument returns true.
2f1dfbe1
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78 */
79static void __batadv_dat_purge(struct batadv_priv *bat_priv,
80 bool (*to_purge)(struct batadv_dat_entry *))
81{
82 spinlock_t *list_lock; /* protects write access to the hash lists */
83 struct batadv_dat_entry *dat_entry;
b67bfe0d 84 struct hlist_node *node_tmp;
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85 struct hlist_head *head;
86 uint32_t i;
87
88 if (!bat_priv->dat.hash)
89 return;
90
91 for (i = 0; i < bat_priv->dat.hash->size; i++) {
92 head = &bat_priv->dat.hash->table[i];
93 list_lock = &bat_priv->dat.hash->list_locks[i];
94
95 spin_lock_bh(list_lock);
b67bfe0d 96 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
2f1dfbe1 97 hash_entry) {
93178018 98 /* if a helper function has been passed as parameter,
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99 * ask it if the entry has to be purged or not
100 */
101 if (to_purge && !to_purge(dat_entry))
102 continue;
103
b67bfe0d 104 hlist_del_rcu(&dat_entry->hash_entry);
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105 batadv_dat_entry_free_ref(dat_entry);
106 }
107 spin_unlock_bh(list_lock);
108 }
109}
110
111/**
112 * batadv_dat_purge - periodic task that deletes old entries from the local DAT
113 * hash table
114 * @work: kernel work struct
115 */
116static void batadv_dat_purge(struct work_struct *work)
117{
118 struct delayed_work *delayed_work;
119 struct batadv_priv_dat *priv_dat;
120 struct batadv_priv *bat_priv;
121
122 delayed_work = container_of(work, struct delayed_work, work);
123 priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
124 bat_priv = container_of(priv_dat, struct batadv_priv, dat);
125
126 __batadv_dat_purge(bat_priv, batadv_dat_to_purge);
127 batadv_dat_start_timer(bat_priv);
128}
129
130/**
131 * batadv_compare_dat - comparing function used in the local DAT hash table
132 * @node: node in the local table
133 * @data2: second object to compare the node to
134 *
93178018 135 * Returns 1 if the two entries are the same, 0 otherwise.
2f1dfbe1
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136 */
137static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
138{
139 const void *data1 = container_of(node, struct batadv_dat_entry,
140 hash_entry);
141
36484f84 142 return memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0;
2f1dfbe1
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143}
144
5c3a0e55
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145/**
146 * batadv_arp_hw_src - extract the hw_src field from an ARP packet
147 * @skb: ARP packet
148 * @hdr_size: size of the possible header before the ARP packet
149 *
93178018 150 * Returns the value of the hw_src field in the ARP packet.
5c3a0e55
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151 */
152static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
153{
154 uint8_t *addr;
155
156 addr = (uint8_t *)(skb->data + hdr_size);
157 addr += ETH_HLEN + sizeof(struct arphdr);
158
159 return addr;
160}
161
162/**
163 * batadv_arp_ip_src - extract the ip_src field from an ARP packet
164 * @skb: ARP packet
165 * @hdr_size: size of the possible header before the ARP packet
166 *
93178018 167 * Returns the value of the ip_src field in the ARP packet.
5c3a0e55
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168 */
169static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
170{
171 return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
172}
173
174/**
175 * batadv_arp_hw_dst - extract the hw_dst field from an ARP packet
176 * @skb: ARP packet
177 * @hdr_size: size of the possible header before the ARP packet
178 *
93178018 179 * Returns the value of the hw_dst field in the ARP packet.
5c3a0e55
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180 */
181static uint8_t *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
182{
183 return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
184}
185
186/**
187 * batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
188 * @skb: ARP packet
189 * @hdr_size: size of the possible header before the ARP packet
190 *
93178018 191 * Returns the value of the ip_dst field in the ARP packet.
5c3a0e55
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192 */
193static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
194{
195 return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
196}
197
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198/**
199 * batadv_hash_dat - compute the hash value for an IP address
200 * @data: data to hash
201 * @size: size of the hash table
202 *
93178018 203 * Returns the selected index in the hash table for the given data.
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204 */
205static uint32_t batadv_hash_dat(const void *data, uint32_t size)
206{
785ea114 207 uint32_t hash = 0;
be1db4f6 208 const struct batadv_dat_entry *dat = data;
785ea114 209
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210 hash = batadv_hash_bytes(hash, &dat->ip, sizeof(dat->ip));
211 hash = batadv_hash_bytes(hash, &dat->vid, sizeof(dat->vid));
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212
213 hash += (hash << 3);
214 hash ^= (hash >> 11);
215 hash += (hash << 15);
216
217 return hash % size;
218}
219
2f1dfbe1 220/**
93178018 221 * batadv_dat_entry_hash_find - look for a given dat_entry in the local hash
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222 * table
223 * @bat_priv: the bat priv with all the soft interface information
224 * @ip: search key
be1db4f6 225 * @vid: VLAN identifier
2f1dfbe1 226 *
93178018 227 * Returns the dat_entry if found, NULL otherwise.
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228 */
229static struct batadv_dat_entry *
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230batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
231 unsigned short vid)
2f1dfbe1
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232{
233 struct hlist_head *head;
be1db4f6 234 struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
2f1dfbe1
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235 struct batadv_hashtable *hash = bat_priv->dat.hash;
236 uint32_t index;
237
238 if (!hash)
239 return NULL;
240
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241 to_find.ip = ip;
242 to_find.vid = vid;
243
244 index = batadv_hash_dat(&to_find, hash->size);
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245 head = &hash->table[index];
246
247 rcu_read_lock();
b67bfe0d 248 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
2f1dfbe1
AQ
249 if (dat_entry->ip != ip)
250 continue;
251
252 if (!atomic_inc_not_zero(&dat_entry->refcount))
253 continue;
254
255 dat_entry_tmp = dat_entry;
256 break;
257 }
258 rcu_read_unlock();
259
260 return dat_entry_tmp;
261}
262
263/**
264 * batadv_dat_entry_add - add a new dat entry or update it if already exists
265 * @bat_priv: the bat priv with all the soft interface information
266 * @ip: ipv4 to add/edit
267 * @mac_addr: mac address to assign to the given ipv4
be1db4f6 268 * @vid: VLAN identifier
2f1dfbe1
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269 */
270static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
be1db4f6 271 uint8_t *mac_addr, unsigned short vid)
2f1dfbe1
AQ
272{
273 struct batadv_dat_entry *dat_entry;
274 int hash_added;
275
be1db4f6 276 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
2f1dfbe1
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277 /* if this entry is already known, just update it */
278 if (dat_entry) {
279 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
8fdd0153 280 ether_addr_copy(dat_entry->mac_addr, mac_addr);
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281 dat_entry->last_update = jiffies;
282 batadv_dbg(BATADV_DBG_DAT, bat_priv,
be1db4f6
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283 "Entry updated: %pI4 %pM (vid: %d)\n",
284 &dat_entry->ip, dat_entry->mac_addr,
285 BATADV_PRINT_VID(vid));
2f1dfbe1
AQ
286 goto out;
287 }
288
289 dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
290 if (!dat_entry)
291 goto out;
292
293 dat_entry->ip = ip;
be1db4f6 294 dat_entry->vid = vid;
8fdd0153 295 ether_addr_copy(dat_entry->mac_addr, mac_addr);
2f1dfbe1
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296 dat_entry->last_update = jiffies;
297 atomic_set(&dat_entry->refcount, 2);
298
299 hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
be1db4f6 300 batadv_hash_dat, dat_entry,
2f1dfbe1
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301 &dat_entry->hash_entry);
302
303 if (unlikely(hash_added != 0)) {
304 /* remove the reference for the hash */
305 batadv_dat_entry_free_ref(dat_entry);
306 goto out;
307 }
308
be1db4f6
AQ
309 batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
310 &dat_entry->ip, dat_entry->mac_addr, BATADV_PRINT_VID(vid));
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311
312out:
313 if (dat_entry)
314 batadv_dat_entry_free_ref(dat_entry);
315}
316
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317#ifdef CONFIG_BATMAN_ADV_DEBUG
318
319/**
320 * batadv_dbg_arp - print a debug message containing all the ARP packet details
321 * @bat_priv: the bat priv with all the soft interface information
322 * @skb: ARP packet
323 * @type: ARP type
324 * @hdr_size: size of the possible header before the ARP packet
325 * @msg: message to print together with the debugging information
326 */
327static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
328 uint16_t type, int hdr_size, char *msg)
329{
330 struct batadv_unicast_4addr_packet *unicast_4addr_packet;
331 struct batadv_bcast_packet *bcast_pkt;
332 uint8_t *orig_addr;
333 __be32 ip_src, ip_dst;
334
335 if (msg)
336 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
337
338 ip_src = batadv_arp_ip_src(skb, hdr_size);
339 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
340 batadv_dbg(BATADV_DBG_DAT, bat_priv,
341 "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
342 batadv_arp_hw_src(skb, hdr_size), &ip_src,
343 batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
344
345 if (hdr_size == 0)
346 return;
347
5c3a0e55
AQ
348 unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
349
a40d9b07 350 switch (unicast_4addr_packet->u.packet_type) {
5c3a0e55
AQ
351 case BATADV_UNICAST:
352 batadv_dbg(BATADV_DBG_DAT, bat_priv,
353 "* encapsulated within a UNICAST packet\n");
354 break;
355 case BATADV_UNICAST_4ADDR:
356 batadv_dbg(BATADV_DBG_DAT, bat_priv,
357 "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
358 unicast_4addr_packet->src);
359 switch (unicast_4addr_packet->subtype) {
360 case BATADV_P_DAT_DHT_PUT:
361 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
362 break;
363 case BATADV_P_DAT_DHT_GET:
364 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
365 break;
366 case BATADV_P_DAT_CACHE_REPLY:
367 batadv_dbg(BATADV_DBG_DAT, bat_priv,
368 "* type: DAT_CACHE_REPLY\n");
369 break;
370 case BATADV_P_DATA:
371 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
372 break;
373 default:
374 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
a40d9b07 375 unicast_4addr_packet->u.packet_type);
5c3a0e55
AQ
376 }
377 break;
378 case BATADV_BCAST:
379 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
380 orig_addr = bcast_pkt->orig;
381 batadv_dbg(BATADV_DBG_DAT, bat_priv,
382 "* encapsulated within a BCAST packet (src: %pM)\n",
383 orig_addr);
384 break;
385 default:
386 batadv_dbg(BATADV_DBG_DAT, bat_priv,
387 "* encapsulated within an unknown packet type (0x%x)\n",
a40d9b07 388 unicast_4addr_packet->u.packet_type);
5c3a0e55
AQ
389 }
390}
391
392#else
393
394static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
395 uint16_t type, int hdr_size, char *msg)
396{
397}
398
399#endif /* CONFIG_BATMAN_ADV_DEBUG */
400
785ea114
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401/**
402 * batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
403 * @res: the array with the already selected candidates
404 * @select: number of already selected candidates
405 * @tmp_max: address of the currently evaluated node
406 * @max: current round max address
407 * @last_max: address of the last selected candidate
408 * @candidate: orig_node under evaluation
409 * @max_orig_node: last selected candidate
410 *
93178018
ML
411 * Returns true if the node has been elected as next candidate or false
412 * otherwise.
785ea114
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413 */
414static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
415 int select, batadv_dat_addr_t tmp_max,
416 batadv_dat_addr_t max,
417 batadv_dat_addr_t last_max,
418 struct batadv_orig_node *candidate,
419 struct batadv_orig_node *max_orig_node)
420{
421 bool ret = false;
422 int j;
423
17cf0ea4
ML
424 /* check if orig node candidate is running DAT */
425 if (!(candidate->capabilities & BATADV_ORIG_CAPA_HAS_DAT))
426 goto out;
427
785ea114
AQ
428 /* Check if this node has already been selected... */
429 for (j = 0; j < select; j++)
430 if (res[j].orig_node == candidate)
431 break;
432 /* ..and possibly skip it */
433 if (j < select)
434 goto out;
435 /* sanity check: has it already been selected? This should not happen */
436 if (tmp_max > last_max)
437 goto out;
438 /* check if during this iteration an originator with a closer dht
439 * address has already been found
440 */
441 if (tmp_max < max)
442 goto out;
443 /* this is an hash collision with the temporary selected node. Choose
444 * the one with the lowest address
445 */
816cd5b8 446 if ((tmp_max == max) && max_orig_node &&
785ea114
AQ
447 (batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
448 goto out;
449
450 ret = true;
451out:
452 return ret;
453}
454
455/**
456 * batadv_choose_next_candidate - select the next DHT candidate
457 * @bat_priv: the bat priv with all the soft interface information
458 * @cands: candidates array
459 * @select: number of candidates already present in the array
460 * @ip_key: key to look up in the DHT
461 * @last_max: pointer where the address of the selected candidate will be saved
462 */
463static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
464 struct batadv_dat_candidate *cands,
465 int select, batadv_dat_addr_t ip_key,
466 batadv_dat_addr_t *last_max)
467{
468 batadv_dat_addr_t max = 0, tmp_max = 0;
469 struct batadv_orig_node *orig_node, *max_orig_node = NULL;
470 struct batadv_hashtable *hash = bat_priv->orig_hash;
785ea114
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471 struct hlist_head *head;
472 int i;
473
474 /* if no node is eligible as candidate, leave the candidate type as
475 * NOT_FOUND
476 */
477 cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
478
93178018 479 /* iterate over the originator list and find the node with the closest
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480 * dat_address which has not been selected yet
481 */
482 for (i = 0; i < hash->size; i++) {
483 head = &hash->table[i];
484
485 rcu_read_lock();
b67bfe0d 486 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
93178018 487 /* the dht space is a ring using unsigned addresses */
785ea114
AQ
488 tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
489 ip_key;
490
491 if (!batadv_is_orig_node_eligible(cands, select,
492 tmp_max, max,
493 *last_max, orig_node,
494 max_orig_node))
495 continue;
496
497 if (!atomic_inc_not_zero(&orig_node->refcount))
498 continue;
499
500 max = tmp_max;
501 if (max_orig_node)
502 batadv_orig_node_free_ref(max_orig_node);
503 max_orig_node = orig_node;
504 }
505 rcu_read_unlock();
506 }
507 if (max_orig_node) {
508 cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
509 cands[select].orig_node = max_orig_node;
510 batadv_dbg(BATADV_DBG_DAT, bat_priv,
511 "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
512 select, max_orig_node->orig, max_orig_node->dat_addr,
513 max);
514 }
515 *last_max = max;
516}
517
518/**
93178018 519 * batadv_dat_select_candidates - select the nodes which the DHT message has to
785ea114
AQ
520 * be sent to
521 * @bat_priv: the bat priv with all the soft interface information
522 * @ip_dst: ipv4 to look up in the DHT
523 *
524 * An originator O is selected if and only if its DHT_ID value is one of three
525 * closest values (from the LEFT, with wrap around if needed) then the hash
526 * value of the key. ip_dst is the key.
527 *
93178018 528 * Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM.
785ea114
AQ
529 */
530static struct batadv_dat_candidate *
531batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
532{
533 int select;
534 batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
535 struct batadv_dat_candidate *res;
536
537 if (!bat_priv->orig_hash)
538 return NULL;
539
540 res = kmalloc(BATADV_DAT_CANDIDATES_NUM * sizeof(*res), GFP_ATOMIC);
541 if (!res)
542 return NULL;
543
544 ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
545 BATADV_DAT_ADDR_MAX);
546
547 batadv_dbg(BATADV_DBG_DAT, bat_priv,
548 "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
549 ip_key);
550
551 for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
552 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
553 &last_max);
554
555 return res;
556}
557
558/**
559 * batadv_dat_send_data - send a payload to the selected candidates
560 * @bat_priv: the bat priv with all the soft interface information
561 * @skb: payload to send
562 * @ip: the DHT key
563 * @packet_subtype: unicast4addr packet subtype to use
564 *
93178018
ML
565 * This function copies the skb with pskb_copy() and is sent as unicast packet
566 * to each of the selected candidates.
785ea114 567 *
93178018
ML
568 * Returns true if the packet is sent to at least one candidate, false
569 * otherwise.
785ea114
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570 */
571static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
572 struct sk_buff *skb, __be32 ip,
573 int packet_subtype)
574{
575 int i;
576 bool ret = false;
577 int send_status;
578 struct batadv_neigh_node *neigh_node = NULL;
579 struct sk_buff *tmp_skb;
580 struct batadv_dat_candidate *cand;
581
582 cand = batadv_dat_select_candidates(bat_priv, ip);
583 if (!cand)
584 goto out;
585
586 batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
587
588 for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
589 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
590 continue;
591
7351a482
SW
592 neigh_node = batadv_orig_router_get(cand[i].orig_node,
593 BATADV_IF_DEFAULT);
785ea114
AQ
594 if (!neigh_node)
595 goto free_orig;
596
bad93e9d 597 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
f097e25d
MH
598 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
599 cand[i].orig_node,
600 packet_subtype)) {
785ea114
AQ
601 kfree_skb(tmp_skb);
602 goto free_neigh;
603 }
604
605 send_status = batadv_send_skb_packet(tmp_skb,
606 neigh_node->if_incoming,
607 neigh_node->addr);
4046b24a
MH
608 if (send_status == NET_XMIT_SUCCESS) {
609 /* count the sent packet */
610 switch (packet_subtype) {
611 case BATADV_P_DAT_DHT_GET:
612 batadv_inc_counter(bat_priv,
613 BATADV_CNT_DAT_GET_TX);
614 break;
615 case BATADV_P_DAT_DHT_PUT:
616 batadv_inc_counter(bat_priv,
617 BATADV_CNT_DAT_PUT_TX);
618 break;
619 }
620
785ea114
AQ
621 /* packet sent to a candidate: return true */
622 ret = true;
4046b24a 623 }
785ea114
AQ
624free_neigh:
625 batadv_neigh_node_free_ref(neigh_node);
626free_orig:
627 batadv_orig_node_free_ref(cand[i].orig_node);
628 }
629
630out:
631 kfree(cand);
632 return ret;
633}
2f1dfbe1 634
17cf0ea4
ML
635/**
636 * batadv_dat_tvlv_container_update - update the dat tvlv container after dat
637 * setting change
638 * @bat_priv: the bat priv with all the soft interface information
639 */
640static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
641{
642 char dat_mode;
643
644 dat_mode = atomic_read(&bat_priv->distributed_arp_table);
645
646 switch (dat_mode) {
647 case 0:
648 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
649 break;
650 case 1:
651 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
652 NULL, 0);
653 break;
654 }
655}
656
657/**
658 * batadv_dat_status_update - update the dat tvlv container after dat
659 * setting change
660 * @net_dev: the soft interface net device
661 */
662void batadv_dat_status_update(struct net_device *net_dev)
663{
664 struct batadv_priv *bat_priv = netdev_priv(net_dev);
f138694b 665
17cf0ea4
ML
666 batadv_dat_tvlv_container_update(bat_priv);
667}
668
669/**
670 * batadv_gw_tvlv_ogm_handler_v1 - process incoming dat tvlv container
671 * @bat_priv: the bat priv with all the soft interface information
672 * @orig: the orig_node of the ogm
673 * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
674 * @tvlv_value: tvlv buffer containing the gateway data
675 * @tvlv_value_len: tvlv buffer length
676 */
677static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
678 struct batadv_orig_node *orig,
679 uint8_t flags,
680 void *tvlv_value,
681 uint16_t tvlv_value_len)
682{
683 if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
684 orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_DAT;
685 else
686 orig->capabilities |= BATADV_ORIG_CAPA_HAS_DAT;
687}
688
2f1dfbe1
AQ
689/**
690 * batadv_dat_hash_free - free the local DAT hash table
691 * @bat_priv: the bat priv with all the soft interface information
692 */
693static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
694{
33af49ad
AQ
695 if (!bat_priv->dat.hash)
696 return;
697
2f1dfbe1
AQ
698 __batadv_dat_purge(bat_priv, NULL);
699
700 batadv_hash_destroy(bat_priv->dat.hash);
701
702 bat_priv->dat.hash = NULL;
703}
704
705/**
706 * batadv_dat_init - initialise the DAT internals
707 * @bat_priv: the bat priv with all the soft interface information
708 */
709int batadv_dat_init(struct batadv_priv *bat_priv)
710{
711 if (bat_priv->dat.hash)
712 return 0;
713
714 bat_priv->dat.hash = batadv_hash_new(1024);
715
716 if (!bat_priv->dat.hash)
717 return -ENOMEM;
718
719 batadv_dat_start_timer(bat_priv);
720
17cf0ea4
ML
721 batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
722 NULL, BATADV_TVLV_DAT, 1,
723 BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
724 batadv_dat_tvlv_container_update(bat_priv);
2f1dfbe1
AQ
725 return 0;
726}
727
728/**
729 * batadv_dat_free - free the DAT internals
730 * @bat_priv: the bat priv with all the soft interface information
731 */
732void batadv_dat_free(struct batadv_priv *bat_priv)
733{
17cf0ea4
ML
734 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
735 batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
736
2f1dfbe1
AQ
737 cancel_delayed_work_sync(&bat_priv->dat.work);
738
739 batadv_dat_hash_free(bat_priv);
740}
741
742/**
743 * batadv_dat_cache_seq_print_text - print the local DAT hash table
744 * @seq: seq file to print on
745 * @offset: not used
746 */
747int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
748{
749 struct net_device *net_dev = (struct net_device *)seq->private;
750 struct batadv_priv *bat_priv = netdev_priv(net_dev);
751 struct batadv_hashtable *hash = bat_priv->dat.hash;
752 struct batadv_dat_entry *dat_entry;
753 struct batadv_hard_iface *primary_if;
2f1dfbe1
AQ
754 struct hlist_head *head;
755 unsigned long last_seen_jiffies;
756 int last_seen_msecs, last_seen_secs, last_seen_mins;
757 uint32_t i;
758
759 primary_if = batadv_seq_print_text_primary_if_get(seq);
760 if (!primary_if)
761 goto out;
762
763 seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
be1db4f6
AQ
764 seq_printf(seq, " %-7s %-9s %4s %11s\n", "IPv4",
765 "MAC", "VID", "last-seen");
2f1dfbe1
AQ
766
767 for (i = 0; i < hash->size; i++) {
768 head = &hash->table[i];
769
770 rcu_read_lock();
b67bfe0d 771 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
2f1dfbe1
AQ
772 last_seen_jiffies = jiffies - dat_entry->last_update;
773 last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
774 last_seen_mins = last_seen_msecs / 60000;
775 last_seen_msecs = last_seen_msecs % 60000;
776 last_seen_secs = last_seen_msecs / 1000;
777
be1db4f6 778 seq_printf(seq, " * %15pI4 %14pM %4i %6i:%02i\n",
2f1dfbe1 779 &dat_entry->ip, dat_entry->mac_addr,
be1db4f6 780 BATADV_PRINT_VID(dat_entry->vid),
2f1dfbe1
AQ
781 last_seen_mins, last_seen_secs);
782 }
783 rcu_read_unlock();
784 }
785
786out:
787 if (primary_if)
788 batadv_hardif_free_ref(primary_if);
789 return 0;
790}
5c3a0e55
AQ
791
792/**
793 * batadv_arp_get_type - parse an ARP packet and gets the type
794 * @bat_priv: the bat priv with all the soft interface information
795 * @skb: packet to analyse
796 * @hdr_size: size of the possible header before the ARP packet in the skb
797 *
93178018 798 * Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise.
5c3a0e55
AQ
799 */
800static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
801 struct sk_buff *skb, int hdr_size)
802{
803 struct arphdr *arphdr;
804 struct ethhdr *ethhdr;
805 __be32 ip_src, ip_dst;
b618ad11 806 uint8_t *hw_src, *hw_dst;
5c3a0e55
AQ
807 uint16_t type = 0;
808
809 /* pull the ethernet header */
810 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
811 goto out;
812
813 ethhdr = (struct ethhdr *)(skb->data + hdr_size);
814
815 if (ethhdr->h_proto != htons(ETH_P_ARP))
816 goto out;
817
818 /* pull the ARP payload */
819 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
820 arp_hdr_len(skb->dev))))
821 goto out;
822
823 arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
824
93178018 825 /* check whether the ARP packet carries a valid IP information */
5c3a0e55
AQ
826 if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
827 goto out;
828
829 if (arphdr->ar_pro != htons(ETH_P_IP))
830 goto out;
831
832 if (arphdr->ar_hln != ETH_ALEN)
833 goto out;
834
835 if (arphdr->ar_pln != 4)
836 goto out;
837
838 /* Check for bad reply/request. If the ARP message is not sane, DAT
839 * will simply ignore it
840 */
841 ip_src = batadv_arp_ip_src(skb, hdr_size);
842 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
843 if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
757dd82e
MS
844 ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
845 ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
846 ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
5c3a0e55
AQ
847 goto out;
848
b618ad11
MS
849 hw_src = batadv_arp_hw_src(skb, hdr_size);
850 if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
851 goto out;
852
93178018 853 /* don't care about the destination MAC address in ARP requests */
b618ad11
MS
854 if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
855 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
856 if (is_zero_ether_addr(hw_dst) ||
857 is_multicast_ether_addr(hw_dst))
858 goto out;
859 }
860
5c3a0e55
AQ
861 type = ntohs(arphdr->ar_op);
862out:
863 return type;
864}
c384ea3e 865
be1db4f6
AQ
866/**
867 * batadv_dat_get_vid - extract the VLAN identifier from skb if any
868 * @skb: the buffer containing the packet to extract the VID from
869 * @hdr_size: the size of the batman-adv header encapsulating the packet
870 *
871 * If the packet embedded in the skb is vlan tagged this function returns the
872 * VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS is returned.
873 */
874static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
875{
876 unsigned short vid;
877
878 vid = batadv_get_vid(skb, *hdr_size);
879
880 /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
881 * If the header contained in the packet is a VLAN one (which is longer)
882 * hdr_size is updated so that the functions will still skip the
883 * correct amount of bytes.
884 */
885 if (vid & BATADV_VLAN_HAS_TAG)
886 *hdr_size += VLAN_HLEN;
887
888 return vid;
889}
890
c384ea3e
AQ
891/**
892 * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to
893 * answer using DAT
894 * @bat_priv: the bat priv with all the soft interface information
895 * @skb: packet to check
896 *
897 * Returns true if the message has been sent to the dht candidates, false
93178018
ML
898 * otherwise. In case of a positive return value the message has to be enqueued
899 * to permit the fallback.
c384ea3e
AQ
900 */
901bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
902 struct sk_buff *skb)
903{
904 uint16_t type = 0;
905 __be32 ip_dst, ip_src;
906 uint8_t *hw_src;
907 bool ret = false;
908 struct batadv_dat_entry *dat_entry = NULL;
909 struct sk_buff *skb_new;
be1db4f6
AQ
910 int hdr_size = 0;
911 unsigned short vid;
c384ea3e 912
33af49ad
AQ
913 if (!atomic_read(&bat_priv->distributed_arp_table))
914 goto out;
915
be1db4f6
AQ
916 vid = batadv_dat_get_vid(skb, &hdr_size);
917
918 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
c384ea3e
AQ
919 /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
920 * message to the selected DHT candidates
921 */
922 if (type != ARPOP_REQUEST)
923 goto out;
924
be1db4f6
AQ
925 batadv_dbg_arp(bat_priv, skb, type, hdr_size,
926 "Parsing outgoing ARP REQUEST");
c384ea3e 927
be1db4f6
AQ
928 ip_src = batadv_arp_ip_src(skb, hdr_size);
929 hw_src = batadv_arp_hw_src(skb, hdr_size);
930 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
c384ea3e 931
be1db4f6 932 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
c384ea3e 933
be1db4f6 934 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
c384ea3e 935 if (dat_entry) {
88e48d7b
AQ
936 /* If the ARP request is destined for a local client the local
937 * client will answer itself. DAT would only generate a
938 * duplicate packet.
939 *
940 * Moreover, if the soft-interface is enslaved into a bridge, an
941 * additional DAT answer may trigger kernel warnings about
942 * a packet coming from the wrong port.
943 */
cc2f3386 944 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
88e48d7b
AQ
945 ret = true;
946 goto out;
947 }
948
c384ea3e 949 skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
736292c2 950 bat_priv->soft_iface, ip_dst, hw_src,
c384ea3e
AQ
951 dat_entry->mac_addr, hw_src);
952 if (!skb_new)
953 goto out;
954
be1db4f6
AQ
955 if (vid & BATADV_VLAN_HAS_TAG)
956 skb_new = vlan_insert_tag(skb_new, htons(ETH_P_8021Q),
957 vid & VLAN_VID_MASK);
958
c384ea3e
AQ
959 skb_reset_mac_header(skb_new);
960 skb_new->protocol = eth_type_trans(skb_new,
736292c2 961 bat_priv->soft_iface);
c384ea3e 962 bat_priv->stats.rx_packets++;
be1db4f6 963 bat_priv->stats.rx_bytes += skb->len + ETH_HLEN + hdr_size;
736292c2 964 bat_priv->soft_iface->last_rx = jiffies;
c384ea3e
AQ
965
966 netif_rx(skb_new);
967 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
968 ret = true;
969 } else {
93178018 970 /* Send the request to the DHT */
c384ea3e
AQ
971 ret = batadv_dat_send_data(bat_priv, skb, ip_dst,
972 BATADV_P_DAT_DHT_GET);
973 }
974out:
975 if (dat_entry)
976 batadv_dat_entry_free_ref(dat_entry);
c384ea3e
AQ
977 return ret;
978}
979
980/**
981 * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to
982 * answer using the local DAT storage
983 * @bat_priv: the bat priv with all the soft interface information
984 * @skb: packet to check
985 * @hdr_size: size of the encapsulation header
986 *
93178018 987 * Returns true if the request has been answered, false otherwise.
c384ea3e
AQ
988 */
989bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
990 struct sk_buff *skb, int hdr_size)
991{
992 uint16_t type;
993 __be32 ip_src, ip_dst;
994 uint8_t *hw_src;
995 struct sk_buff *skb_new;
c384ea3e
AQ
996 struct batadv_dat_entry *dat_entry = NULL;
997 bool ret = false;
be1db4f6 998 unsigned short vid;
c384ea3e
AQ
999 int err;
1000
33af49ad
AQ
1001 if (!atomic_read(&bat_priv->distributed_arp_table))
1002 goto out;
1003
be1db4f6
AQ
1004 vid = batadv_dat_get_vid(skb, &hdr_size);
1005
c384ea3e
AQ
1006 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1007 if (type != ARPOP_REQUEST)
1008 goto out;
1009
1010 hw_src = batadv_arp_hw_src(skb, hdr_size);
1011 ip_src = batadv_arp_ip_src(skb, hdr_size);
1012 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1013
1014 batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1015 "Parsing incoming ARP REQUEST");
1016
be1db4f6 1017 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
c384ea3e 1018
be1db4f6 1019 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
c384ea3e
AQ
1020 if (!dat_entry)
1021 goto out;
1022
c384ea3e 1023 skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
736292c2 1024 bat_priv->soft_iface, ip_dst, hw_src,
c384ea3e
AQ
1025 dat_entry->mac_addr, hw_src);
1026
1027 if (!skb_new)
1028 goto out;
1029
927c2ed7
LL
1030 /* the rest of the TX path assumes that the mac_header offset pointing
1031 * to the inner Ethernet header has been set, therefore reset it now.
1032 */
1033 skb_reset_mac_header(skb_new);
1034
be1db4f6
AQ
1035 if (vid & BATADV_VLAN_HAS_TAG)
1036 skb_new = vlan_insert_tag(skb_new, htons(ETH_P_8021Q),
1037 vid & VLAN_VID_MASK);
1038
93178018
ML
1039 /* To preserve backwards compatibility, the node has choose the outgoing
1040 * format based on the incoming request packet type. The assumption is
1041 * that a node not using the 4addr packet format doesn't support it.
c384ea3e
AQ
1042 */
1043 if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
e300d314
LL
1044 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1045 BATADV_P_DAT_CACHE_REPLY,
6c413b1c 1046 NULL, vid);
c384ea3e 1047 else
6c413b1c 1048 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
c384ea3e 1049
e300d314 1050 if (err != NET_XMIT_DROP) {
4046b24a 1051 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
c384ea3e 1052 ret = true;
4046b24a 1053 }
c384ea3e
AQ
1054out:
1055 if (dat_entry)
1056 batadv_dat_entry_free_ref(dat_entry);
c384ea3e
AQ
1057 if (ret)
1058 kfree_skb(skb);
1059 return ret;
1060}
1061
1062/**
1063 * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT
1064 * @bat_priv: the bat priv with all the soft interface information
1065 * @skb: packet to check
1066 */
1067void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1068 struct sk_buff *skb)
1069{
1070 uint16_t type;
1071 __be32 ip_src, ip_dst;
1072 uint8_t *hw_src, *hw_dst;
be1db4f6
AQ
1073 int hdr_size = 0;
1074 unsigned short vid;
c384ea3e 1075
33af49ad
AQ
1076 if (!atomic_read(&bat_priv->distributed_arp_table))
1077 return;
1078
be1db4f6
AQ
1079 vid = batadv_dat_get_vid(skb, &hdr_size);
1080
1081 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
c384ea3e
AQ
1082 if (type != ARPOP_REPLY)
1083 return;
1084
be1db4f6
AQ
1085 batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1086 "Parsing outgoing ARP REPLY");
c384ea3e 1087
be1db4f6
AQ
1088 hw_src = batadv_arp_hw_src(skb, hdr_size);
1089 ip_src = batadv_arp_ip_src(skb, hdr_size);
1090 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1091 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
c384ea3e 1092
be1db4f6
AQ
1093 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1094 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
c384ea3e
AQ
1095
1096 /* Send the ARP reply to the candidates for both the IP addresses that
93178018 1097 * the node obtained from the ARP reply
c384ea3e
AQ
1098 */
1099 batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);
1100 batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);
1101}
1102/**
1103 * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
1104 * DAT storage only
1105 * @bat_priv: the bat priv with all the soft interface information
1106 * @skb: packet to check
93178018 1107 * @hdr_size: size of the encapsulation header
c384ea3e
AQ
1108 */
1109bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1110 struct sk_buff *skb, int hdr_size)
1111{
1112 uint16_t type;
1113 __be32 ip_src, ip_dst;
1114 uint8_t *hw_src, *hw_dst;
1115 bool ret = false;
be1db4f6 1116 unsigned short vid;
c384ea3e 1117
33af49ad
AQ
1118 if (!atomic_read(&bat_priv->distributed_arp_table))
1119 goto out;
1120
be1db4f6
AQ
1121 vid = batadv_dat_get_vid(skb, &hdr_size);
1122
c384ea3e
AQ
1123 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1124 if (type != ARPOP_REPLY)
1125 goto out;
1126
1127 batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1128 "Parsing incoming ARP REPLY");
1129
1130 hw_src = batadv_arp_hw_src(skb, hdr_size);
1131 ip_src = batadv_arp_ip_src(skb, hdr_size);
1132 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1133 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1134
1135 /* Update our internal cache with both the IP addresses the node got
1136 * within the ARP reply
1137 */
be1db4f6
AQ
1138 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1139 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
c384ea3e
AQ
1140
1141 /* if this REPLY is directed to a client of mine, let's deliver the
1142 * packet to the interface
1143 */
be1db4f6 1144 ret = !batadv_is_my_client(bat_priv, hw_dst, vid);
c384ea3e 1145out:
0d15bece
MS
1146 if (ret)
1147 kfree_skb(skb);
c384ea3e
AQ
1148 /* if ret == false -> packet has to be delivered to the interface */
1149 return ret;
1150}
1151
1152/**
1153 * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped
93178018 1154 * (because the node has already obtained the reply via DAT) or not
c384ea3e
AQ
1155 * @bat_priv: the bat priv with all the soft interface information
1156 * @forw_packet: the broadcast packet
1157 *
93178018 1158 * Returns true if the node can drop the packet, false otherwise.
c384ea3e
AQ
1159 */
1160bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1161 struct batadv_forw_packet *forw_packet)
1162{
1163 uint16_t type;
1164 __be32 ip_dst;
1165 struct batadv_dat_entry *dat_entry = NULL;
1166 bool ret = false;
be1db4f6
AQ
1167 int hdr_size = sizeof(struct batadv_bcast_packet);
1168 unsigned short vid;
c384ea3e 1169
33af49ad
AQ
1170 if (!atomic_read(&bat_priv->distributed_arp_table))
1171 goto out;
1172
c384ea3e
AQ
1173 /* If this packet is an ARP_REQUEST and the node already has the
1174 * information that it is going to ask, then the packet can be dropped
1175 */
1176 if (forw_packet->num_packets)
1177 goto out;
1178
be1db4f6
AQ
1179 vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1180
1181 type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
c384ea3e
AQ
1182 if (type != ARPOP_REQUEST)
1183 goto out;
1184
be1db4f6
AQ
1185 ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1186 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
c384ea3e
AQ
1187 /* check if the node already got this entry */
1188 if (!dat_entry) {
1189 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1190 "ARP Request for %pI4: fallback\n", &ip_dst);
1191 goto out;
1192 }
1193
1194 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1195 "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1196 ret = true;
1197
1198out:
1199 if (dat_entry)
1200 batadv_dat_entry_free_ref(dat_entry);
1201 return ret;
1202}