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TOMOYO Linux Cross Reference
Linux/net/batman-adv/distributed-arp-table.c

Version: ~ [ linux-5.6-rc3 ] ~ [ linux-5.5.7 ] ~ [ linux-5.4.23 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.107 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.172 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.215 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.215 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* Copyright (C) 2011-2014 B.A.T.M.A.N. contributors:
  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
 15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
 16  */
 17 
 18 #include <linux/if_ether.h>
 19 #include <linux/if_arp.h>
 20 #include <linux/if_vlan.h>
 21 #include <net/arp.h>
 22 
 23 #include "main.h"
 24 #include "hash.h"
 25 #include "distributed-arp-table.h"
 26 #include "hard-interface.h"
 27 #include "originator.h"
 28 #include "send.h"
 29 #include "types.h"
 30 #include "translation-table.h"
 31 
 32 static 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  */
 38 static 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 /**
 46  * batadv_dat_entry_free_ref - decrement the dat_entry refcounter and possibly
 47  * free it
 48  * @dat_entry: the entry to free
 49  */
 50 static 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 /**
 57  * batadv_dat_to_purge - check whether a dat_entry has to be purged or not
 58  * @dat_entry: the entry to check
 59  *
 60  * Returns true if the entry has to be purged now, false otherwise.
 61  */
 62 static 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  *
 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.
 78  */
 79 static 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;
 84         struct hlist_node *node_tmp;
 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);
 96                 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
 97                                           hash_entry) {
 98                         /* if a helper function has been passed as parameter,
 99                          * ask it if the entry has to be purged or not
100                          */
101                         if (to_purge && !to_purge(dat_entry))
102                                 continue;
103 
104                         hlist_del_rcu(&dat_entry->hash_entry);
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  */
116 static 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  *
135  * Returns 1 if the two entries are the same, 0 otherwise.
136  */
137 static 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 
142         return memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0;
143 }
144 
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  *
150  * Returns the value of the hw_src field in the ARP packet.
151  */
152 static 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  *
167  * Returns the value of the ip_src field in the ARP packet.
168  */
169 static __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  *
179  * Returns the value of the hw_dst field in the ARP packet.
180  */
181 static 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  *
191  * Returns the value of the ip_dst field in the ARP packet.
192  */
193 static __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 
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  *
203  * Returns the selected index in the hash table for the given data.
204  */
205 static uint32_t batadv_hash_dat(const void *data, uint32_t size)
206 {
207         uint32_t hash = 0;
208         const struct batadv_dat_entry *dat = data;
209 
210         hash = batadv_hash_bytes(hash, &dat->ip, sizeof(dat->ip));
211         hash = batadv_hash_bytes(hash, &dat->vid, sizeof(dat->vid));
212 
213         hash += (hash << 3);
214         hash ^= (hash >> 11);
215         hash += (hash << 15);
216 
217         return hash % size;
218 }
219 
220 /**
221  * batadv_dat_entry_hash_find - look for a given dat_entry in the local hash
222  * table
223  * @bat_priv: the bat priv with all the soft interface information
224  * @ip: search key
225  * @vid: VLAN identifier
226  *
227  * Returns the dat_entry if found, NULL otherwise.
228  */
229 static struct batadv_dat_entry *
230 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
231                            unsigned short vid)
232 {
233         struct hlist_head *head;
234         struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
235         struct batadv_hashtable *hash = bat_priv->dat.hash;
236         uint32_t index;
237 
238         if (!hash)
239                 return NULL;
240 
241         to_find.ip = ip;
242         to_find.vid = vid;
243 
244         index = batadv_hash_dat(&to_find, hash->size);
245         head = &hash->table[index];
246 
247         rcu_read_lock();
248         hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
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
268  * @vid: VLAN identifier
269  */
270 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
271                                  uint8_t *mac_addr, unsigned short vid)
272 {
273         struct batadv_dat_entry *dat_entry;
274         int hash_added;
275 
276         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
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))
280                         ether_addr_copy(dat_entry->mac_addr, mac_addr);
281                 dat_entry->last_update = jiffies;
282                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
283                            "Entry updated: %pI4 %pM (vid: %d)\n",
284                            &dat_entry->ip, dat_entry->mac_addr,
285                            BATADV_PRINT_VID(vid));
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;
294         dat_entry->vid = vid;
295         ether_addr_copy(dat_entry->mac_addr, mac_addr);
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,
300                                      batadv_hash_dat, dat_entry,
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 
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));
311 
312 out:
313         if (dat_entry)
314                 batadv_dat_entry_free_ref(dat_entry);
315 }
316 
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  */
327 static 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 
348         unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
349 
350         switch (unicast_4addr_packet->u.packet_type) {
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",
375                                    unicast_4addr_packet->u.packet_type);
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",
388                            unicast_4addr_packet->u.packet_type);
389         }
390 }
391 
392 #else
393 
394 static 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 
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  *
411  * Returns true if the node has been elected as next candidate or false
412  * otherwise.
413  */
414 static 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 
424         /* check if orig node candidate is running DAT */
425         if (!(candidate->capabilities & BATADV_ORIG_CAPA_HAS_DAT))
426                 goto out;
427 
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          */
446         if ((tmp_max == max) && max_orig_node &&
447             (batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
448                 goto out;
449 
450         ret = true;
451 out:
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  */
463 static 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;
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 
479         /* iterate over the originator list and find the node with the closest
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();
486                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
487                         /* the dht space is a ring using unsigned addresses */
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 /**
519  * batadv_dat_select_candidates - select the nodes which the DHT message has to
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  *
528  * Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM.
529  */
530 static struct batadv_dat_candidate *
531 batadv_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_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
541                             GFP_ATOMIC);
542         if (!res)
543                 return NULL;
544 
545         ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
546                                                     BATADV_DAT_ADDR_MAX);
547 
548         batadv_dbg(BATADV_DBG_DAT, bat_priv,
549                    "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
550                    ip_key);
551 
552         for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
553                 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
554                                              &last_max);
555 
556         return res;
557 }
558 
559 /**
560  * batadv_dat_send_data - send a payload to the selected candidates
561  * @bat_priv: the bat priv with all the soft interface information
562  * @skb: payload to send
563  * @ip: the DHT key
564  * @packet_subtype: unicast4addr packet subtype to use
565  *
566  * This function copies the skb with pskb_copy() and is sent as unicast packet
567  * to each of the selected candidates.
568  *
569  * Returns true if the packet is sent to at least one candidate, false
570  * otherwise.
571  */
572 static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
573                                  struct sk_buff *skb, __be32 ip,
574                                  int packet_subtype)
575 {
576         int i;
577         bool ret = false;
578         int send_status;
579         struct batadv_neigh_node *neigh_node = NULL;
580         struct sk_buff *tmp_skb;
581         struct batadv_dat_candidate *cand;
582 
583         cand = batadv_dat_select_candidates(bat_priv, ip);
584         if (!cand)
585                 goto out;
586 
587         batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
588 
589         for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
590                 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
591                         continue;
592 
593                 neigh_node = batadv_orig_router_get(cand[i].orig_node,
594                                                     BATADV_IF_DEFAULT);
595                 if (!neigh_node)
596                         goto free_orig;
597 
598                 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
599                 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
600                                                            cand[i].orig_node,
601                                                            packet_subtype)) {
602                         kfree_skb(tmp_skb);
603                         goto free_neigh;
604                 }
605 
606                 send_status = batadv_send_skb_packet(tmp_skb,
607                                                      neigh_node->if_incoming,
608                                                      neigh_node->addr);
609                 if (send_status == NET_XMIT_SUCCESS) {
610                         /* count the sent packet */
611                         switch (packet_subtype) {
612                         case BATADV_P_DAT_DHT_GET:
613                                 batadv_inc_counter(bat_priv,
614                                                    BATADV_CNT_DAT_GET_TX);
615                                 break;
616                         case BATADV_P_DAT_DHT_PUT:
617                                 batadv_inc_counter(bat_priv,
618                                                    BATADV_CNT_DAT_PUT_TX);
619                                 break;
620                         }
621 
622                         /* packet sent to a candidate: return true */
623                         ret = true;
624                 }
625 free_neigh:
626                 batadv_neigh_node_free_ref(neigh_node);
627 free_orig:
628                 batadv_orig_node_free_ref(cand[i].orig_node);
629         }
630 
631 out:
632         kfree(cand);
633         return ret;
634 }
635 
636 /**
637  * batadv_dat_tvlv_container_update - update the dat tvlv container after dat
638  *  setting change
639  * @bat_priv: the bat priv with all the soft interface information
640  */
641 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
642 {
643         char dat_mode;
644 
645         dat_mode = atomic_read(&bat_priv->distributed_arp_table);
646 
647         switch (dat_mode) {
648         case 0:
649                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
650                 break;
651         case 1:
652                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
653                                                NULL, 0);
654                 break;
655         }
656 }
657 
658 /**
659  * batadv_dat_status_update - update the dat tvlv container after dat
660  *  setting change
661  * @net_dev: the soft interface net device
662  */
663 void batadv_dat_status_update(struct net_device *net_dev)
664 {
665         struct batadv_priv *bat_priv = netdev_priv(net_dev);
666 
667         batadv_dat_tvlv_container_update(bat_priv);
668 }
669 
670 /**
671  * batadv_gw_tvlv_ogm_handler_v1 - process incoming dat tvlv container
672  * @bat_priv: the bat priv with all the soft interface information
673  * @orig: the orig_node of the ogm
674  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
675  * @tvlv_value: tvlv buffer containing the gateway data
676  * @tvlv_value_len: tvlv buffer length
677  */
678 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
679                                            struct batadv_orig_node *orig,
680                                            uint8_t flags,
681                                            void *tvlv_value,
682                                            uint16_t tvlv_value_len)
683 {
684         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
685                 orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_DAT;
686         else
687                 orig->capabilities |= BATADV_ORIG_CAPA_HAS_DAT;
688 }
689 
690 /**
691  * batadv_dat_hash_free - free the local DAT hash table
692  * @bat_priv: the bat priv with all the soft interface information
693  */
694 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
695 {
696         if (!bat_priv->dat.hash)
697                 return;
698 
699         __batadv_dat_purge(bat_priv, NULL);
700 
701         batadv_hash_destroy(bat_priv->dat.hash);
702 
703         bat_priv->dat.hash = NULL;
704 }
705 
706 /**
707  * batadv_dat_init - initialise the DAT internals
708  * @bat_priv: the bat priv with all the soft interface information
709  */
710 int batadv_dat_init(struct batadv_priv *bat_priv)
711 {
712         if (bat_priv->dat.hash)
713                 return 0;
714 
715         bat_priv->dat.hash = batadv_hash_new(1024);
716 
717         if (!bat_priv->dat.hash)
718                 return -ENOMEM;
719 
720         batadv_dat_start_timer(bat_priv);
721 
722         batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
723                                      NULL, BATADV_TVLV_DAT, 1,
724                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
725         batadv_dat_tvlv_container_update(bat_priv);
726         return 0;
727 }
728 
729 /**
730  * batadv_dat_free - free the DAT internals
731  * @bat_priv: the bat priv with all the soft interface information
732  */
733 void batadv_dat_free(struct batadv_priv *bat_priv)
734 {
735         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
736         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
737 
738         cancel_delayed_work_sync(&bat_priv->dat.work);
739 
740         batadv_dat_hash_free(bat_priv);
741 }
742 
743 /**
744  * batadv_dat_cache_seq_print_text - print the local DAT hash table
745  * @seq: seq file to print on
746  * @offset: not used
747  */
748 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
749 {
750         struct net_device *net_dev = (struct net_device *)seq->private;
751         struct batadv_priv *bat_priv = netdev_priv(net_dev);
752         struct batadv_hashtable *hash = bat_priv->dat.hash;
753         struct batadv_dat_entry *dat_entry;
754         struct batadv_hard_iface *primary_if;
755         struct hlist_head *head;
756         unsigned long last_seen_jiffies;
757         int last_seen_msecs, last_seen_secs, last_seen_mins;
758         uint32_t i;
759 
760         primary_if = batadv_seq_print_text_primary_if_get(seq);
761         if (!primary_if)
762                 goto out;
763 
764         seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
765         seq_printf(seq, "          %-7s          %-9s %4s %11s\n", "IPv4",
766                    "MAC", "VID", "last-seen");
767 
768         for (i = 0; i < hash->size; i++) {
769                 head = &hash->table[i];
770 
771                 rcu_read_lock();
772                 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
773                         last_seen_jiffies = jiffies - dat_entry->last_update;
774                         last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
775                         last_seen_mins = last_seen_msecs / 60000;
776                         last_seen_msecs = last_seen_msecs % 60000;
777                         last_seen_secs = last_seen_msecs / 1000;
778 
779                         seq_printf(seq, " * %15pI4 %14pM %4i %6i:%02i\n",
780                                    &dat_entry->ip, dat_entry->mac_addr,
781                                    BATADV_PRINT_VID(dat_entry->vid),
782                                    last_seen_mins, last_seen_secs);
783                 }
784                 rcu_read_unlock();
785         }
786 
787 out:
788         if (primary_if)
789                 batadv_hardif_free_ref(primary_if);
790         return 0;
791 }
792 
793 /**
794  * batadv_arp_get_type - parse an ARP packet and gets the type
795  * @bat_priv: the bat priv with all the soft interface information
796  * @skb: packet to analyse
797  * @hdr_size: size of the possible header before the ARP packet in the skb
798  *
799  * Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise.
800  */
801 static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
802                                     struct sk_buff *skb, int hdr_size)
803 {
804         struct arphdr *arphdr;
805         struct ethhdr *ethhdr;
806         __be32 ip_src, ip_dst;
807         uint8_t *hw_src, *hw_dst;
808         uint16_t type = 0;
809 
810         /* pull the ethernet header */
811         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
812                 goto out;
813 
814         ethhdr = (struct ethhdr *)(skb->data + hdr_size);
815 
816         if (ethhdr->h_proto != htons(ETH_P_ARP))
817                 goto out;
818 
819         /* pull the ARP payload */
820         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
821                                     arp_hdr_len(skb->dev))))
822                 goto out;
823 
824         arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
825 
826         /* check whether the ARP packet carries a valid IP information */
827         if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
828                 goto out;
829 
830         if (arphdr->ar_pro != htons(ETH_P_IP))
831                 goto out;
832 
833         if (arphdr->ar_hln != ETH_ALEN)
834                 goto out;
835 
836         if (arphdr->ar_pln != 4)
837                 goto out;
838 
839         /* Check for bad reply/request. If the ARP message is not sane, DAT
840          * will simply ignore it
841          */
842         ip_src = batadv_arp_ip_src(skb, hdr_size);
843         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
844         if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
845             ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
846             ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
847             ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
848                 goto out;
849 
850         hw_src = batadv_arp_hw_src(skb, hdr_size);
851         if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
852                 goto out;
853 
854         /* don't care about the destination MAC address in ARP requests */
855         if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
856                 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
857                 if (is_zero_ether_addr(hw_dst) ||
858                     is_multicast_ether_addr(hw_dst))
859                         goto out;
860         }
861 
862         type = ntohs(arphdr->ar_op);
863 out:
864         return type;
865 }
866 
867 /**
868  * batadv_dat_get_vid - extract the VLAN identifier from skb if any
869  * @skb: the buffer containing the packet to extract the VID from
870  * @hdr_size: the size of the batman-adv header encapsulating the packet
871  *
872  * If the packet embedded in the skb is vlan tagged this function returns the
873  * VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS is returned.
874  */
875 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
876 {
877         unsigned short vid;
878 
879         vid = batadv_get_vid(skb, *hdr_size);
880 
881         /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
882          * If the header contained in the packet is a VLAN one (which is longer)
883          * hdr_size is updated so that the functions will still skip the
884          * correct amount of bytes.
885          */
886         if (vid & BATADV_VLAN_HAS_TAG)
887                 *hdr_size += VLAN_HLEN;
888 
889         return vid;
890 }
891 
892 /**
893  * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to
894  * answer using DAT
895  * @bat_priv: the bat priv with all the soft interface information
896  * @skb: packet to check
897  *
898  * Returns true if the message has been sent to the dht candidates, false
899  * otherwise. In case of a positive return value the message has to be enqueued
900  * to permit the fallback.
901  */
902 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
903                                            struct sk_buff *skb)
904 {
905         uint16_t type = 0;
906         __be32 ip_dst, ip_src;
907         uint8_t *hw_src;
908         bool ret = false;
909         struct batadv_dat_entry *dat_entry = NULL;
910         struct sk_buff *skb_new;
911         int hdr_size = 0;
912         unsigned short vid;
913 
914         if (!atomic_read(&bat_priv->distributed_arp_table))
915                 goto out;
916 
917         vid = batadv_dat_get_vid(skb, &hdr_size);
918 
919         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
920         /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
921          * message to the selected DHT candidates
922          */
923         if (type != ARPOP_REQUEST)
924                 goto out;
925 
926         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
927                        "Parsing outgoing ARP REQUEST");
928 
929         ip_src = batadv_arp_ip_src(skb, hdr_size);
930         hw_src = batadv_arp_hw_src(skb, hdr_size);
931         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
932 
933         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
934 
935         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
936         if (dat_entry) {
937                 /* If the ARP request is destined for a local client the local
938                  * client will answer itself. DAT would only generate a
939                  * duplicate packet.
940                  *
941                  * Moreover, if the soft-interface is enslaved into a bridge, an
942                  * additional DAT answer may trigger kernel warnings about
943                  * a packet coming from the wrong port.
944                  */
945                 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
946                         ret = true;
947                         goto out;
948                 }
949 
950                 skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
951                                      bat_priv->soft_iface, ip_dst, hw_src,
952                                      dat_entry->mac_addr, hw_src);
953                 if (!skb_new)
954                         goto out;
955 
956                 if (vid & BATADV_VLAN_HAS_TAG)
957                         skb_new = vlan_insert_tag(skb_new, htons(ETH_P_8021Q),
958                                                   vid & VLAN_VID_MASK);
959 
960                 skb_reset_mac_header(skb_new);
961                 skb_new->protocol = eth_type_trans(skb_new,
962                                                    bat_priv->soft_iface);
963                 bat_priv->stats.rx_packets++;
964                 bat_priv->stats.rx_bytes += skb->len + ETH_HLEN + hdr_size;
965                 bat_priv->soft_iface->last_rx = jiffies;
966 
967                 netif_rx(skb_new);
968                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
969                 ret = true;
970         } else {
971                 /* Send the request to the DHT */
972                 ret = batadv_dat_send_data(bat_priv, skb, ip_dst,
973                                            BATADV_P_DAT_DHT_GET);
974         }
975 out:
976         if (dat_entry)
977                 batadv_dat_entry_free_ref(dat_entry);
978         return ret;
979 }
980 
981 /**
982  * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to
983  * answer using the local DAT storage
984  * @bat_priv: the bat priv with all the soft interface information
985  * @skb: packet to check
986  * @hdr_size: size of the encapsulation header
987  *
988  * Returns true if the request has been answered, false otherwise.
989  */
990 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
991                                            struct sk_buff *skb, int hdr_size)
992 {
993         uint16_t type;
994         __be32 ip_src, ip_dst;
995         uint8_t *hw_src;
996         struct sk_buff *skb_new;
997         struct batadv_dat_entry *dat_entry = NULL;
998         bool ret = false;
999         unsigned short vid;
1000         int err;
1001 
1002         if (!atomic_read(&bat_priv->distributed_arp_table))
1003                 goto out;
1004 
1005         vid = batadv_dat_get_vid(skb, &hdr_size);
1006 
1007         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1008         if (type != ARPOP_REQUEST)
1009                 goto out;
1010 
1011         hw_src = batadv_arp_hw_src(skb, hdr_size);
1012         ip_src = batadv_arp_ip_src(skb, hdr_size);
1013         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1014 
1015         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1016                        "Parsing incoming ARP REQUEST");
1017 
1018         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1019 
1020         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1021         if (!dat_entry)
1022                 goto out;
1023 
1024         skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
1025                              bat_priv->soft_iface, ip_dst, hw_src,
1026                              dat_entry->mac_addr, hw_src);
1027 
1028         if (!skb_new)
1029                 goto out;
1030 
1031         /* the rest of the TX path assumes that the mac_header offset pointing
1032          * to the inner Ethernet header has been set, therefore reset it now.
1033          */
1034         skb_reset_mac_header(skb_new);
1035 
1036         if (vid & BATADV_VLAN_HAS_TAG)
1037                 skb_new = vlan_insert_tag(skb_new, htons(ETH_P_8021Q),
1038                                           vid & VLAN_VID_MASK);
1039 
1040         /* To preserve backwards compatibility, the node has choose the outgoing
1041          * format based on the incoming request packet type. The assumption is
1042          * that a node not using the 4addr packet format doesn't support it.
1043          */
1044         if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1045                 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1046                                                    BATADV_P_DAT_CACHE_REPLY,
1047                                                    NULL, vid);
1048         else
1049                 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1050 
1051         if (err != NET_XMIT_DROP) {
1052                 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1053                 ret = true;
1054         }
1055 out:
1056         if (dat_entry)
1057                 batadv_dat_entry_free_ref(dat_entry);
1058         if (ret)
1059                 kfree_skb(skb);
1060         return ret;
1061 }
1062 
1063 /**
1064  * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT
1065  * @bat_priv: the bat priv with all the soft interface information
1066  * @skb: packet to check
1067  */
1068 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1069                                          struct sk_buff *skb)
1070 {
1071         uint16_t type;
1072         __be32 ip_src, ip_dst;
1073         uint8_t *hw_src, *hw_dst;
1074         int hdr_size = 0;
1075         unsigned short vid;
1076 
1077         if (!atomic_read(&bat_priv->distributed_arp_table))
1078                 return;
1079 
1080         vid = batadv_dat_get_vid(skb, &hdr_size);
1081 
1082         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1083         if (type != ARPOP_REPLY)
1084                 return;
1085 
1086         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1087                        "Parsing outgoing ARP REPLY");
1088 
1089         hw_src = batadv_arp_hw_src(skb, hdr_size);
1090         ip_src = batadv_arp_ip_src(skb, hdr_size);
1091         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1092         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1093 
1094         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1095         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1096 
1097         /* Send the ARP reply to the candidates for both the IP addresses that
1098          * the node obtained from the ARP reply
1099          */
1100         batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);
1101         batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);
1102 }
1103 /**
1104  * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
1105  * DAT storage only
1106  * @bat_priv: the bat priv with all the soft interface information
1107  * @skb: packet to check
1108  * @hdr_size: size of the encapsulation header
1109  */
1110 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1111                                          struct sk_buff *skb, int hdr_size)
1112 {
1113         uint16_t type;
1114         __be32 ip_src, ip_dst;
1115         uint8_t *hw_src, *hw_dst;
1116         bool ret = false;
1117         unsigned short vid;
1118 
1119         if (!atomic_read(&bat_priv->distributed_arp_table))
1120                 goto out;
1121 
1122         vid = batadv_dat_get_vid(skb, &hdr_size);
1123 
1124         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1125         if (type != ARPOP_REPLY)
1126                 goto out;
1127 
1128         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1129                        "Parsing incoming ARP REPLY");
1130 
1131         hw_src = batadv_arp_hw_src(skb, hdr_size);
1132         ip_src = batadv_arp_ip_src(skb, hdr_size);
1133         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1134         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1135 
1136         /* Update our internal cache with both the IP addresses the node got
1137          * within the ARP reply
1138          */
1139         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1140         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1141 
1142         /* if this REPLY is directed to a client of mine, let's deliver the
1143          * packet to the interface
1144          */
1145         ret = !batadv_is_my_client(bat_priv, hw_dst, vid);
1146 out:
1147         if (ret)
1148                 kfree_skb(skb);
1149         /* if ret == false -> packet has to be delivered to the interface */
1150         return ret;
1151 }
1152 
1153 /**
1154  * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped
1155  * (because the node has already obtained the reply via DAT) or not
1156  * @bat_priv: the bat priv with all the soft interface information
1157  * @forw_packet: the broadcast packet
1158  *
1159  * Returns true if the node can drop the packet, false otherwise.
1160  */
1161 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1162                                       struct batadv_forw_packet *forw_packet)
1163 {
1164         uint16_t type;
1165         __be32 ip_dst;
1166         struct batadv_dat_entry *dat_entry = NULL;
1167         bool ret = false;
1168         int hdr_size = sizeof(struct batadv_bcast_packet);
1169         unsigned short vid;
1170 
1171         if (!atomic_read(&bat_priv->distributed_arp_table))
1172                 goto out;
1173 
1174         /* If this packet is an ARP_REQUEST and the node already has the
1175          * information that it is going to ask, then the packet can be dropped
1176          */
1177         if (forw_packet->num_packets)
1178                 goto out;
1179 
1180         vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1181 
1182         type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1183         if (type != ARPOP_REQUEST)
1184                 goto out;
1185 
1186         ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1187         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1188         /* check if the node already got this entry */
1189         if (!dat_entry) {
1190                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1191                            "ARP Request for %pI4: fallback\n", &ip_dst);
1192                 goto out;
1193         }
1194 
1195         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1196                    "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1197         ret = true;
1198 
1199 out:
1200         if (dat_entry)
1201                 batadv_dat_entry_free_ref(dat_entry);
1202         return ret;
1203 }
1204 

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