1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2011-2019  B.A.T.M.A.N. contributors:
3  *
4  * Antonio Quartulli
5  */
6 
7 #include "distributed-arp-table.h"
8 #include "main.h"
9 
10 #include <asm/unaligned.h>
11 #include <linux/atomic.h>
12 #include <linux/bitops.h>
13 #include <linux/byteorder/generic.h>
14 #include <linux/errno.h>
15 #include <linux/etherdevice.h>
16 #include <linux/gfp.h>
17 #include <linux/if_arp.h>
18 #include <linux/if_ether.h>
19 #include <linux/if_vlan.h>
20 #include <linux/in.h>
21 #include <linux/ip.h>
22 #include <linux/jiffies.h>
23 #include <linux/kernel.h>
24 #include <linux/kref.h>
25 #include <linux/list.h>
26 #include <linux/netlink.h>
27 #include <linux/rculist.h>
28 #include <linux/rcupdate.h>
29 #include <linux/seq_file.h>
30 #include <linux/skbuff.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
33 #include <linux/stddef.h>
34 #include <linux/string.h>
35 #include <linux/udp.h>
36 #include <linux/workqueue.h>
37 #include <net/arp.h>
38 #include <net/genetlink.h>
39 #include <net/netlink.h>
40 #include <net/sock.h>
41 #include <uapi/linux/batman_adv.h>
42 
43 #include "bridge_loop_avoidance.h"
44 #include "hard-interface.h"
45 #include "hash.h"
46 #include "log.h"
47 #include "netlink.h"
48 #include "originator.h"
49 #include "send.h"
50 #include "soft-interface.h"
51 #include "translation-table.h"
52 #include "tvlv.h"
53 
54 enum batadv_bootpop {
55 	BATADV_BOOTREPLY	= 2,
56 };
57 
58 enum batadv_boothtype {
59 	BATADV_HTYPE_ETHERNET	= 1,
60 };
61 
62 enum batadv_dhcpoptioncode {
63 	BATADV_DHCP_OPT_PAD		= 0,
64 	BATADV_DHCP_OPT_MSG_TYPE	= 53,
65 	BATADV_DHCP_OPT_END		= 255,
66 };
67 
68 enum batadv_dhcptype {
69 	BATADV_DHCPACK		= 5,
70 };
71 
72 /* { 99, 130, 83, 99 } */
73 #define BATADV_DHCP_MAGIC 1669485411
74 
75 struct batadv_dhcp_packet {
76 	__u8 op;
77 	__u8 htype;
78 	__u8 hlen;
79 	__u8 hops;
80 	__be32 xid;
81 	__be16 secs;
82 	__be16 flags;
83 	__be32 ciaddr;
84 	__be32 yiaddr;
85 	__be32 siaddr;
86 	__be32 giaddr;
87 	__u8 chaddr[16];
88 	__u8 sname[64];
89 	__u8 file[128];
90 	__be32 magic;
91 	__u8 options[0];
92 };
93 
94 #define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
95 #define BATADV_DHCP_CHADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->chaddr)
96 
97 static void batadv_dat_purge(struct work_struct *work);
98 
99 /**
100  * batadv_dat_start_timer() - initialise the DAT periodic worker
101  * @bat_priv: the bat priv with all the soft interface information
102  */
103 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
104 {
105 	INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
106 	queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
107 			   msecs_to_jiffies(10000));
108 }
109 
110 /**
111  * batadv_dat_entry_release() - release dat_entry from lists and queue for free
112  *  after rcu grace period
113  * @ref: kref pointer of the dat_entry
114  */
115 static void batadv_dat_entry_release(struct kref *ref)
116 {
117 	struct batadv_dat_entry *dat_entry;
118 
119 	dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
120 
121 	kfree_rcu(dat_entry, rcu);
122 }
123 
124 /**
125  * batadv_dat_entry_put() - decrement the dat_entry refcounter and possibly
126  *  release it
127  * @dat_entry: dat_entry to be free'd
128  */
129 static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
130 {
131 	kref_put(&dat_entry->refcount, batadv_dat_entry_release);
132 }
133 
134 /**
135  * batadv_dat_to_purge() - check whether a dat_entry has to be purged or not
136  * @dat_entry: the entry to check
137  *
138  * Return: true if the entry has to be purged now, false otherwise.
139  */
140 static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
141 {
142 	return batadv_has_timed_out(dat_entry->last_update,
143 				    BATADV_DAT_ENTRY_TIMEOUT);
144 }
145 
146 /**
147  * __batadv_dat_purge() - delete entries from the DAT local storage
148  * @bat_priv: the bat priv with all the soft interface information
149  * @to_purge: function in charge to decide whether an entry has to be purged or
150  *	      not. This function takes the dat_entry as argument and has to
151  *	      returns a boolean value: true is the entry has to be deleted,
152  *	      false otherwise
153  *
154  * Loops over each entry in the DAT local storage and deletes it if and only if
155  * the to_purge function passed as argument returns true.
156  */
157 static void __batadv_dat_purge(struct batadv_priv *bat_priv,
158 			       bool (*to_purge)(struct batadv_dat_entry *))
159 {
160 	spinlock_t *list_lock; /* protects write access to the hash lists */
161 	struct batadv_dat_entry *dat_entry;
162 	struct hlist_node *node_tmp;
163 	struct hlist_head *head;
164 	u32 i;
165 
166 	if (!bat_priv->dat.hash)
167 		return;
168 
169 	for (i = 0; i < bat_priv->dat.hash->size; i++) {
170 		head = &bat_priv->dat.hash->table[i];
171 		list_lock = &bat_priv->dat.hash->list_locks[i];
172 
173 		spin_lock_bh(list_lock);
174 		hlist_for_each_entry_safe(dat_entry, node_tmp, head,
175 					  hash_entry) {
176 			/* if a helper function has been passed as parameter,
177 			 * ask it if the entry has to be purged or not
178 			 */
179 			if (to_purge && !to_purge(dat_entry))
180 				continue;
181 
182 			hlist_del_rcu(&dat_entry->hash_entry);
183 			batadv_dat_entry_put(dat_entry);
184 		}
185 		spin_unlock_bh(list_lock);
186 	}
187 }
188 
189 /**
190  * batadv_dat_purge() - periodic task that deletes old entries from the local
191  *  DAT hash table
192  * @work: kernel work struct
193  */
194 static void batadv_dat_purge(struct work_struct *work)
195 {
196 	struct delayed_work *delayed_work;
197 	struct batadv_priv_dat *priv_dat;
198 	struct batadv_priv *bat_priv;
199 
200 	delayed_work = to_delayed_work(work);
201 	priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
202 	bat_priv = container_of(priv_dat, struct batadv_priv, dat);
203 
204 	__batadv_dat_purge(bat_priv, batadv_dat_to_purge);
205 	batadv_dat_start_timer(bat_priv);
206 }
207 
208 /**
209  * batadv_compare_dat() - comparing function used in the local DAT hash table
210  * @node: node in the local table
211  * @data2: second object to compare the node to
212  *
213  * Return: true if the two entries are the same, false otherwise.
214  */
215 static bool batadv_compare_dat(const struct hlist_node *node, const void *data2)
216 {
217 	const void *data1 = container_of(node, struct batadv_dat_entry,
218 					 hash_entry);
219 
220 	return memcmp(data1, data2, sizeof(__be32)) == 0;
221 }
222 
223 /**
224  * batadv_arp_hw_src() - extract the hw_src field from an ARP packet
225  * @skb: ARP packet
226  * @hdr_size: size of the possible header before the ARP packet
227  *
228  * Return: the value of the hw_src field in the ARP packet.
229  */
230 static u8 *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
231 {
232 	u8 *addr;
233 
234 	addr = (u8 *)(skb->data + hdr_size);
235 	addr += ETH_HLEN + sizeof(struct arphdr);
236 
237 	return addr;
238 }
239 
240 /**
241  * batadv_arp_ip_src() - extract the ip_src field from an ARP packet
242  * @skb: ARP packet
243  * @hdr_size: size of the possible header before the ARP packet
244  *
245  * Return: the value of the ip_src field in the ARP packet.
246  */
247 static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
248 {
249 	return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
250 }
251 
252 /**
253  * batadv_arp_hw_dst() - extract the hw_dst field from an ARP packet
254  * @skb: ARP packet
255  * @hdr_size: size of the possible header before the ARP packet
256  *
257  * Return: the value of the hw_dst field in the ARP packet.
258  */
259 static u8 *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
260 {
261 	return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
262 }
263 
264 /**
265  * batadv_arp_ip_dst() - extract the ip_dst field from an ARP packet
266  * @skb: ARP packet
267  * @hdr_size: size of the possible header before the ARP packet
268  *
269  * Return: the value of the ip_dst field in the ARP packet.
270  */
271 static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
272 {
273 	return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
274 }
275 
276 /**
277  * batadv_hash_dat() - compute the hash value for an IP address
278  * @data: data to hash
279  * @size: size of the hash table
280  *
281  * Return: the selected index in the hash table for the given data.
282  */
283 static u32 batadv_hash_dat(const void *data, u32 size)
284 {
285 	u32 hash = 0;
286 	const struct batadv_dat_entry *dat = data;
287 	const unsigned char *key;
288 	u32 i;
289 
290 	key = (const unsigned char *)&dat->ip;
291 	for (i = 0; i < sizeof(dat->ip); i++) {
292 		hash += key[i];
293 		hash += (hash << 10);
294 		hash ^= (hash >> 6);
295 	}
296 
297 	key = (const unsigned char *)&dat->vid;
298 	for (i = 0; i < sizeof(dat->vid); i++) {
299 		hash += key[i];
300 		hash += (hash << 10);
301 		hash ^= (hash >> 6);
302 	}
303 
304 	hash += (hash << 3);
305 	hash ^= (hash >> 11);
306 	hash += (hash << 15);
307 
308 	return hash % size;
309 }
310 
311 /**
312  * batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
313  * table
314  * @bat_priv: the bat priv with all the soft interface information
315  * @ip: search key
316  * @vid: VLAN identifier
317  *
318  * Return: the dat_entry if found, NULL otherwise.
319  */
320 static struct batadv_dat_entry *
321 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
322 			   unsigned short vid)
323 {
324 	struct hlist_head *head;
325 	struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
326 	struct batadv_hashtable *hash = bat_priv->dat.hash;
327 	u32 index;
328 
329 	if (!hash)
330 		return NULL;
331 
332 	to_find.ip = ip;
333 	to_find.vid = vid;
334 
335 	index = batadv_hash_dat(&to_find, hash->size);
336 	head = &hash->table[index];
337 
338 	rcu_read_lock();
339 	hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
340 		if (dat_entry->ip != ip)
341 			continue;
342 
343 		if (!kref_get_unless_zero(&dat_entry->refcount))
344 			continue;
345 
346 		dat_entry_tmp = dat_entry;
347 		break;
348 	}
349 	rcu_read_unlock();
350 
351 	return dat_entry_tmp;
352 }
353 
354 /**
355  * batadv_dat_entry_add() - add a new dat entry or update it if already exists
356  * @bat_priv: the bat priv with all the soft interface information
357  * @ip: ipv4 to add/edit
358  * @mac_addr: mac address to assign to the given ipv4
359  * @vid: VLAN identifier
360  */
361 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
362 				 u8 *mac_addr, unsigned short vid)
363 {
364 	struct batadv_dat_entry *dat_entry;
365 	int hash_added;
366 
367 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
368 	/* if this entry is already known, just update it */
369 	if (dat_entry) {
370 		if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
371 			ether_addr_copy(dat_entry->mac_addr, mac_addr);
372 		dat_entry->last_update = jiffies;
373 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
374 			   "Entry updated: %pI4 %pM (vid: %d)\n",
375 			   &dat_entry->ip, dat_entry->mac_addr,
376 			   batadv_print_vid(vid));
377 		goto out;
378 	}
379 
380 	dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
381 	if (!dat_entry)
382 		goto out;
383 
384 	dat_entry->ip = ip;
385 	dat_entry->vid = vid;
386 	ether_addr_copy(dat_entry->mac_addr, mac_addr);
387 	dat_entry->last_update = jiffies;
388 	kref_init(&dat_entry->refcount);
389 
390 	kref_get(&dat_entry->refcount);
391 	hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
392 				     batadv_hash_dat, dat_entry,
393 				     &dat_entry->hash_entry);
394 
395 	if (unlikely(hash_added != 0)) {
396 		/* remove the reference for the hash */
397 		batadv_dat_entry_put(dat_entry);
398 		goto out;
399 	}
400 
401 	batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
402 		   &dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
403 
404 out:
405 	if (dat_entry)
406 		batadv_dat_entry_put(dat_entry);
407 }
408 
409 #ifdef CONFIG_BATMAN_ADV_DEBUG
410 
411 /**
412  * batadv_dbg_arp() - print a debug message containing all the ARP packet
413  *  details
414  * @bat_priv: the bat priv with all the soft interface information
415  * @skb: ARP packet
416  * @hdr_size: size of the possible header before the ARP packet
417  * @msg: message to print together with the debugging information
418  */
419 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
420 			   int hdr_size, char *msg)
421 {
422 	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
423 	struct batadv_bcast_packet *bcast_pkt;
424 	u8 *orig_addr;
425 	__be32 ip_src, ip_dst;
426 
427 	if (msg)
428 		batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
429 
430 	ip_src = batadv_arp_ip_src(skb, hdr_size);
431 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
432 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
433 		   "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
434 		   batadv_arp_hw_src(skb, hdr_size), &ip_src,
435 		   batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
436 
437 	if (hdr_size < sizeof(struct batadv_unicast_packet))
438 		return;
439 
440 	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
441 
442 	switch (unicast_4addr_packet->u.packet_type) {
443 	case BATADV_UNICAST:
444 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
445 			   "* encapsulated within a UNICAST packet\n");
446 		break;
447 	case BATADV_UNICAST_4ADDR:
448 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
449 			   "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
450 			   unicast_4addr_packet->src);
451 		switch (unicast_4addr_packet->subtype) {
452 		case BATADV_P_DAT_DHT_PUT:
453 			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
454 			break;
455 		case BATADV_P_DAT_DHT_GET:
456 			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
457 			break;
458 		case BATADV_P_DAT_CACHE_REPLY:
459 			batadv_dbg(BATADV_DBG_DAT, bat_priv,
460 				   "* type: DAT_CACHE_REPLY\n");
461 			break;
462 		case BATADV_P_DATA:
463 			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
464 			break;
465 		default:
466 			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
467 				   unicast_4addr_packet->u.packet_type);
468 		}
469 		break;
470 	case BATADV_BCAST:
471 		bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
472 		orig_addr = bcast_pkt->orig;
473 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
474 			   "* encapsulated within a BCAST packet (src: %pM)\n",
475 			   orig_addr);
476 		break;
477 	default:
478 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
479 			   "* encapsulated within an unknown packet type (0x%x)\n",
480 			   unicast_4addr_packet->u.packet_type);
481 	}
482 }
483 
484 #else
485 
486 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
487 			   int hdr_size, char *msg)
488 {
489 }
490 
491 #endif /* CONFIG_BATMAN_ADV_DEBUG */
492 
493 /**
494  * batadv_is_orig_node_eligible() - check whether a node can be a DHT candidate
495  * @res: the array with the already selected candidates
496  * @select: number of already selected candidates
497  * @tmp_max: address of the currently evaluated node
498  * @max: current round max address
499  * @last_max: address of the last selected candidate
500  * @candidate: orig_node under evaluation
501  * @max_orig_node: last selected candidate
502  *
503  * Return: true if the node has been elected as next candidate or false
504  * otherwise.
505  */
506 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
507 					 int select, batadv_dat_addr_t tmp_max,
508 					 batadv_dat_addr_t max,
509 					 batadv_dat_addr_t last_max,
510 					 struct batadv_orig_node *candidate,
511 					 struct batadv_orig_node *max_orig_node)
512 {
513 	bool ret = false;
514 	int j;
515 
516 	/* check if orig node candidate is running DAT */
517 	if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
518 		goto out;
519 
520 	/* Check if this node has already been selected... */
521 	for (j = 0; j < select; j++)
522 		if (res[j].orig_node == candidate)
523 			break;
524 	/* ..and possibly skip it */
525 	if (j < select)
526 		goto out;
527 	/* sanity check: has it already been selected? This should not happen */
528 	if (tmp_max > last_max)
529 		goto out;
530 	/* check if during this iteration an originator with a closer dht
531 	 * address has already been found
532 	 */
533 	if (tmp_max < max)
534 		goto out;
535 	/* this is an hash collision with the temporary selected node. Choose
536 	 * the one with the lowest address
537 	 */
538 	if (tmp_max == max && max_orig_node &&
539 	    batadv_compare_eth(candidate->orig, max_orig_node->orig))
540 		goto out;
541 
542 	ret = true;
543 out:
544 	return ret;
545 }
546 
547 /**
548  * batadv_choose_next_candidate() - select the next DHT candidate
549  * @bat_priv: the bat priv with all the soft interface information
550  * @cands: candidates array
551  * @select: number of candidates already present in the array
552  * @ip_key: key to look up in the DHT
553  * @last_max: pointer where the address of the selected candidate will be saved
554  */
555 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
556 					 struct batadv_dat_candidate *cands,
557 					 int select, batadv_dat_addr_t ip_key,
558 					 batadv_dat_addr_t *last_max)
559 {
560 	batadv_dat_addr_t max = 0;
561 	batadv_dat_addr_t tmp_max = 0;
562 	struct batadv_orig_node *orig_node, *max_orig_node = NULL;
563 	struct batadv_hashtable *hash = bat_priv->orig_hash;
564 	struct hlist_head *head;
565 	int i;
566 
567 	/* if no node is eligible as candidate, leave the candidate type as
568 	 * NOT_FOUND
569 	 */
570 	cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
571 
572 	/* iterate over the originator list and find the node with the closest
573 	 * dat_address which has not been selected yet
574 	 */
575 	for (i = 0; i < hash->size; i++) {
576 		head = &hash->table[i];
577 
578 		rcu_read_lock();
579 		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
580 			/* the dht space is a ring using unsigned addresses */
581 			tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
582 				  ip_key;
583 
584 			if (!batadv_is_orig_node_eligible(cands, select,
585 							  tmp_max, max,
586 							  *last_max, orig_node,
587 							  max_orig_node))
588 				continue;
589 
590 			if (!kref_get_unless_zero(&orig_node->refcount))
591 				continue;
592 
593 			max = tmp_max;
594 			if (max_orig_node)
595 				batadv_orig_node_put(max_orig_node);
596 			max_orig_node = orig_node;
597 		}
598 		rcu_read_unlock();
599 	}
600 	if (max_orig_node) {
601 		cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
602 		cands[select].orig_node = max_orig_node;
603 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
604 			   "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
605 			   select, max_orig_node->orig, max_orig_node->dat_addr,
606 			   max);
607 	}
608 	*last_max = max;
609 }
610 
611 /**
612  * batadv_dat_select_candidates() - select the nodes which the DHT message has
613  *  to be sent to
614  * @bat_priv: the bat priv with all the soft interface information
615  * @ip_dst: ipv4 to look up in the DHT
616  * @vid: VLAN identifier
617  *
618  * An originator O is selected if and only if its DHT_ID value is one of three
619  * closest values (from the LEFT, with wrap around if needed) then the hash
620  * value of the key. ip_dst is the key.
621  *
622  * Return: the candidate array of size BATADV_DAT_CANDIDATE_NUM.
623  */
624 static struct batadv_dat_candidate *
625 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
626 			     unsigned short vid)
627 {
628 	int select;
629 	batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
630 	struct batadv_dat_candidate *res;
631 	struct batadv_dat_entry dat;
632 
633 	if (!bat_priv->orig_hash)
634 		return NULL;
635 
636 	res = kmalloc_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
637 			    GFP_ATOMIC);
638 	if (!res)
639 		return NULL;
640 
641 	dat.ip = ip_dst;
642 	dat.vid = vid;
643 	ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
644 						    BATADV_DAT_ADDR_MAX);
645 
646 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
647 		   "%s(): IP=%pI4 hash(IP)=%u\n", __func__, &ip_dst,
648 		   ip_key);
649 
650 	for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
651 		batadv_choose_next_candidate(bat_priv, res, select, ip_key,
652 					     &last_max);
653 
654 	return res;
655 }
656 
657 /**
658  * batadv_dat_forward_data() - copy and send payload to the selected candidates
659  * @bat_priv: the bat priv with all the soft interface information
660  * @skb: payload to send
661  * @ip: the DHT key
662  * @vid: VLAN identifier
663  * @packet_subtype: unicast4addr packet subtype to use
664  *
665  * This function copies the skb with pskb_copy() and is sent as unicast packet
666  * to each of the selected candidates.
667  *
668  * Return: true if the packet is sent to at least one candidate, false
669  * otherwise.
670  */
671 static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
672 				    struct sk_buff *skb, __be32 ip,
673 				    unsigned short vid, int packet_subtype)
674 {
675 	int i;
676 	bool ret = false;
677 	int send_status;
678 	struct batadv_neigh_node *neigh_node = NULL;
679 	struct sk_buff *tmp_skb;
680 	struct batadv_dat_candidate *cand;
681 
682 	cand = batadv_dat_select_candidates(bat_priv, ip, vid);
683 	if (!cand)
684 		goto out;
685 
686 	batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
687 
688 	for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
689 		if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
690 			continue;
691 
692 		neigh_node = batadv_orig_router_get(cand[i].orig_node,
693 						    BATADV_IF_DEFAULT);
694 		if (!neigh_node)
695 			goto free_orig;
696 
697 		tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
698 		if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
699 							   cand[i].orig_node,
700 							   packet_subtype)) {
701 			kfree_skb(tmp_skb);
702 			goto free_neigh;
703 		}
704 
705 		send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
706 		if (send_status == NET_XMIT_SUCCESS) {
707 			/* count the sent packet */
708 			switch (packet_subtype) {
709 			case BATADV_P_DAT_DHT_GET:
710 				batadv_inc_counter(bat_priv,
711 						   BATADV_CNT_DAT_GET_TX);
712 				break;
713 			case BATADV_P_DAT_DHT_PUT:
714 				batadv_inc_counter(bat_priv,
715 						   BATADV_CNT_DAT_PUT_TX);
716 				break;
717 			}
718 
719 			/* packet sent to a candidate: return true */
720 			ret = true;
721 		}
722 free_neigh:
723 		batadv_neigh_node_put(neigh_node);
724 free_orig:
725 		batadv_orig_node_put(cand[i].orig_node);
726 	}
727 
728 out:
729 	kfree(cand);
730 	return ret;
731 }
732 
733 /**
734  * batadv_dat_tvlv_container_update() - update the dat tvlv container after dat
735  *  setting change
736  * @bat_priv: the bat priv with all the soft interface information
737  */
738 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
739 {
740 	char dat_mode;
741 
742 	dat_mode = atomic_read(&bat_priv->distributed_arp_table);
743 
744 	switch (dat_mode) {
745 	case 0:
746 		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
747 		break;
748 	case 1:
749 		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
750 					       NULL, 0);
751 		break;
752 	}
753 }
754 
755 /**
756  * batadv_dat_status_update() - update the dat tvlv container after dat
757  *  setting change
758  * @net_dev: the soft interface net device
759  */
760 void batadv_dat_status_update(struct net_device *net_dev)
761 {
762 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
763 
764 	batadv_dat_tvlv_container_update(bat_priv);
765 }
766 
767 /**
768  * batadv_dat_tvlv_ogm_handler_v1() - process incoming dat tvlv container
769  * @bat_priv: the bat priv with all the soft interface information
770  * @orig: the orig_node of the ogm
771  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
772  * @tvlv_value: tvlv buffer containing the gateway data
773  * @tvlv_value_len: tvlv buffer length
774  */
775 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
776 					   struct batadv_orig_node *orig,
777 					   u8 flags,
778 					   void *tvlv_value, u16 tvlv_value_len)
779 {
780 	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
781 		clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
782 	else
783 		set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
784 }
785 
786 /**
787  * batadv_dat_hash_free() - free the local DAT hash table
788  * @bat_priv: the bat priv with all the soft interface information
789  */
790 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
791 {
792 	if (!bat_priv->dat.hash)
793 		return;
794 
795 	__batadv_dat_purge(bat_priv, NULL);
796 
797 	batadv_hash_destroy(bat_priv->dat.hash);
798 
799 	bat_priv->dat.hash = NULL;
800 }
801 
802 /**
803  * batadv_dat_init() - initialise the DAT internals
804  * @bat_priv: the bat priv with all the soft interface information
805  *
806  * Return: 0 in case of success, a negative error code otherwise
807  */
808 int batadv_dat_init(struct batadv_priv *bat_priv)
809 {
810 	if (bat_priv->dat.hash)
811 		return 0;
812 
813 	bat_priv->dat.hash = batadv_hash_new(1024);
814 
815 	if (!bat_priv->dat.hash)
816 		return -ENOMEM;
817 
818 	batadv_dat_start_timer(bat_priv);
819 
820 	batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
821 				     NULL, BATADV_TVLV_DAT, 1,
822 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
823 	batadv_dat_tvlv_container_update(bat_priv);
824 	return 0;
825 }
826 
827 /**
828  * batadv_dat_free() - free the DAT internals
829  * @bat_priv: the bat priv with all the soft interface information
830  */
831 void batadv_dat_free(struct batadv_priv *bat_priv)
832 {
833 	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
834 	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
835 
836 	cancel_delayed_work_sync(&bat_priv->dat.work);
837 
838 	batadv_dat_hash_free(bat_priv);
839 }
840 
841 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
842 /**
843  * batadv_dat_cache_seq_print_text() - print the local DAT hash table
844  * @seq: seq file to print on
845  * @offset: not used
846  *
847  * Return: always 0
848  */
849 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
850 {
851 	struct net_device *net_dev = (struct net_device *)seq->private;
852 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
853 	struct batadv_hashtable *hash = bat_priv->dat.hash;
854 	struct batadv_dat_entry *dat_entry;
855 	struct batadv_hard_iface *primary_if;
856 	struct hlist_head *head;
857 	unsigned long last_seen_jiffies;
858 	int last_seen_msecs, last_seen_secs, last_seen_mins;
859 	u32 i;
860 
861 	primary_if = batadv_seq_print_text_primary_if_get(seq);
862 	if (!primary_if)
863 		goto out;
864 
865 	seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
866 	seq_puts(seq,
867 		 "          IPv4             MAC        VID   last-seen\n");
868 
869 	for (i = 0; i < hash->size; i++) {
870 		head = &hash->table[i];
871 
872 		rcu_read_lock();
873 		hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
874 			last_seen_jiffies = jiffies - dat_entry->last_update;
875 			last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
876 			last_seen_mins = last_seen_msecs / 60000;
877 			last_seen_msecs = last_seen_msecs % 60000;
878 			last_seen_secs = last_seen_msecs / 1000;
879 
880 			seq_printf(seq, " * %15pI4 %pM %4i %6i:%02i\n",
881 				   &dat_entry->ip, dat_entry->mac_addr,
882 				   batadv_print_vid(dat_entry->vid),
883 				   last_seen_mins, last_seen_secs);
884 		}
885 		rcu_read_unlock();
886 	}
887 
888 out:
889 	if (primary_if)
890 		batadv_hardif_put(primary_if);
891 	return 0;
892 }
893 #endif
894 
895 /**
896  * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
897  *  netlink socket
898  * @msg: buffer for the message
899  * @portid: netlink port
900  * @cb: Control block containing additional options
901  * @dat_entry: entry to dump
902  *
903  * Return: 0 or error code.
904  */
905 static int
906 batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
907 			    struct netlink_callback *cb,
908 			    struct batadv_dat_entry *dat_entry)
909 {
910 	int msecs;
911 	void *hdr;
912 
913 	hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
914 			  &batadv_netlink_family, NLM_F_MULTI,
915 			  BATADV_CMD_GET_DAT_CACHE);
916 	if (!hdr)
917 		return -ENOBUFS;
918 
919 	genl_dump_check_consistent(cb, hdr);
920 
921 	msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
922 
923 	if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
924 			    dat_entry->ip) ||
925 	    nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
926 		    dat_entry->mac_addr) ||
927 	    nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
928 	    nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
929 		genlmsg_cancel(msg, hdr);
930 		return -EMSGSIZE;
931 	}
932 
933 	genlmsg_end(msg, hdr);
934 	return 0;
935 }
936 
937 /**
938  * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
939  *  a netlink socket
940  * @msg: buffer for the message
941  * @portid: netlink port
942  * @cb: Control block containing additional options
943  * @hash: hash to dump
944  * @bucket: bucket index to dump
945  * @idx_skip: How many entries to skip
946  *
947  * Return: 0 or error code.
948  */
949 static int
950 batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
951 			     struct netlink_callback *cb,
952 			     struct batadv_hashtable *hash, unsigned int bucket,
953 			     int *idx_skip)
954 {
955 	struct batadv_dat_entry *dat_entry;
956 	int idx = 0;
957 
958 	spin_lock_bh(&hash->list_locks[bucket]);
959 	cb->seq = atomic_read(&hash->generation) << 1 | 1;
960 
961 	hlist_for_each_entry(dat_entry, &hash->table[bucket], hash_entry) {
962 		if (idx < *idx_skip)
963 			goto skip;
964 
965 		if (batadv_dat_cache_dump_entry(msg, portid, cb, dat_entry)) {
966 			spin_unlock_bh(&hash->list_locks[bucket]);
967 			*idx_skip = idx;
968 
969 			return -EMSGSIZE;
970 		}
971 
972 skip:
973 		idx++;
974 	}
975 	spin_unlock_bh(&hash->list_locks[bucket]);
976 
977 	return 0;
978 }
979 
980 /**
981  * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
982  * @msg: buffer for the message
983  * @cb: callback structure containing arguments
984  *
985  * Return: message length.
986  */
987 int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
988 {
989 	struct batadv_hard_iface *primary_if = NULL;
990 	int portid = NETLINK_CB(cb->skb).portid;
991 	struct net *net = sock_net(cb->skb->sk);
992 	struct net_device *soft_iface;
993 	struct batadv_hashtable *hash;
994 	struct batadv_priv *bat_priv;
995 	int bucket = cb->args[0];
996 	int idx = cb->args[1];
997 	int ifindex;
998 	int ret = 0;
999 
1000 	ifindex = batadv_netlink_get_ifindex(cb->nlh,
1001 					     BATADV_ATTR_MESH_IFINDEX);
1002 	if (!ifindex)
1003 		return -EINVAL;
1004 
1005 	soft_iface = dev_get_by_index(net, ifindex);
1006 	if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
1007 		ret = -ENODEV;
1008 		goto out;
1009 	}
1010 
1011 	bat_priv = netdev_priv(soft_iface);
1012 	hash = bat_priv->dat.hash;
1013 
1014 	primary_if = batadv_primary_if_get_selected(bat_priv);
1015 	if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
1016 		ret = -ENOENT;
1017 		goto out;
1018 	}
1019 
1020 	while (bucket < hash->size) {
1021 		if (batadv_dat_cache_dump_bucket(msg, portid, cb, hash, bucket,
1022 						 &idx))
1023 			break;
1024 
1025 		bucket++;
1026 		idx = 0;
1027 	}
1028 
1029 	cb->args[0] = bucket;
1030 	cb->args[1] = idx;
1031 
1032 	ret = msg->len;
1033 
1034 out:
1035 	if (primary_if)
1036 		batadv_hardif_put(primary_if);
1037 
1038 	if (soft_iface)
1039 		dev_put(soft_iface);
1040 
1041 	return ret;
1042 }
1043 
1044 /**
1045  * batadv_arp_get_type() - parse an ARP packet and gets the type
1046  * @bat_priv: the bat priv with all the soft interface information
1047  * @skb: packet to analyse
1048  * @hdr_size: size of the possible header before the ARP packet in the skb
1049  *
1050  * Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
1051  */
1052 static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
1053 			       struct sk_buff *skb, int hdr_size)
1054 {
1055 	struct arphdr *arphdr;
1056 	struct ethhdr *ethhdr;
1057 	__be32 ip_src, ip_dst;
1058 	u8 *hw_src, *hw_dst;
1059 	u16 type = 0;
1060 
1061 	/* pull the ethernet header */
1062 	if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1063 		goto out;
1064 
1065 	ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1066 
1067 	if (ethhdr->h_proto != htons(ETH_P_ARP))
1068 		goto out;
1069 
1070 	/* pull the ARP payload */
1071 	if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
1072 				    arp_hdr_len(skb->dev))))
1073 		goto out;
1074 
1075 	arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
1076 
1077 	/* check whether the ARP packet carries a valid IP information */
1078 	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
1079 		goto out;
1080 
1081 	if (arphdr->ar_pro != htons(ETH_P_IP))
1082 		goto out;
1083 
1084 	if (arphdr->ar_hln != ETH_ALEN)
1085 		goto out;
1086 
1087 	if (arphdr->ar_pln != 4)
1088 		goto out;
1089 
1090 	/* Check for bad reply/request. If the ARP message is not sane, DAT
1091 	 * will simply ignore it
1092 	 */
1093 	ip_src = batadv_arp_ip_src(skb, hdr_size);
1094 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1095 	if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
1096 	    ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
1097 	    ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
1098 	    ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
1099 		goto out;
1100 
1101 	hw_src = batadv_arp_hw_src(skb, hdr_size);
1102 	if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
1103 		goto out;
1104 
1105 	/* don't care about the destination MAC address in ARP requests */
1106 	if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
1107 		hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1108 		if (is_zero_ether_addr(hw_dst) ||
1109 		    is_multicast_ether_addr(hw_dst))
1110 			goto out;
1111 	}
1112 
1113 	type = ntohs(arphdr->ar_op);
1114 out:
1115 	return type;
1116 }
1117 
1118 /**
1119  * batadv_dat_get_vid() - extract the VLAN identifier from skb if any
1120  * @skb: the buffer containing the packet to extract the VID from
1121  * @hdr_size: the size of the batman-adv header encapsulating the packet
1122  *
1123  * Return: If the packet embedded in the skb is vlan tagged this function
1124  * returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
1125  * is returned.
1126  */
1127 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
1128 {
1129 	unsigned short vid;
1130 
1131 	vid = batadv_get_vid(skb, *hdr_size);
1132 
1133 	/* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
1134 	 * If the header contained in the packet is a VLAN one (which is longer)
1135 	 * hdr_size is updated so that the functions will still skip the
1136 	 * correct amount of bytes.
1137 	 */
1138 	if (vid & BATADV_VLAN_HAS_TAG)
1139 		*hdr_size += VLAN_HLEN;
1140 
1141 	return vid;
1142 }
1143 
1144 /**
1145  * batadv_dat_arp_create_reply() - create an ARP Reply
1146  * @bat_priv: the bat priv with all the soft interface information
1147  * @ip_src: ARP sender IP
1148  * @ip_dst: ARP target IP
1149  * @hw_src: Ethernet source and ARP sender MAC
1150  * @hw_dst: Ethernet destination and ARP target MAC
1151  * @vid: VLAN identifier (optional, set to zero otherwise)
1152  *
1153  * Creates an ARP Reply from the given values, optionally encapsulated in a
1154  * VLAN header.
1155  *
1156  * Return: An skb containing an ARP Reply.
1157  */
1158 static struct sk_buff *
1159 batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
1160 			    __be32 ip_dst, u8 *hw_src, u8 *hw_dst,
1161 			    unsigned short vid)
1162 {
1163 	struct sk_buff *skb;
1164 
1165 	skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->soft_iface,
1166 			 ip_src, hw_dst, hw_src, hw_dst);
1167 	if (!skb)
1168 		return NULL;
1169 
1170 	skb_reset_mac_header(skb);
1171 
1172 	if (vid & BATADV_VLAN_HAS_TAG)
1173 		skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
1174 				      vid & VLAN_VID_MASK);
1175 
1176 	return skb;
1177 }
1178 
1179 /**
1180  * batadv_dat_snoop_outgoing_arp_request() - snoop the ARP request and try to
1181  * answer using DAT
1182  * @bat_priv: the bat priv with all the soft interface information
1183  * @skb: packet to check
1184  *
1185  * Return: true if the message has been sent to the dht candidates, false
1186  * otherwise. In case of a positive return value the message has to be enqueued
1187  * to permit the fallback.
1188  */
1189 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
1190 					   struct sk_buff *skb)
1191 {
1192 	u16 type = 0;
1193 	__be32 ip_dst, ip_src;
1194 	u8 *hw_src;
1195 	bool ret = false;
1196 	struct batadv_dat_entry *dat_entry = NULL;
1197 	struct sk_buff *skb_new;
1198 	struct net_device *soft_iface = bat_priv->soft_iface;
1199 	int hdr_size = 0;
1200 	unsigned short vid;
1201 
1202 	if (!atomic_read(&bat_priv->distributed_arp_table))
1203 		goto out;
1204 
1205 	vid = batadv_dat_get_vid(skb, &hdr_size);
1206 
1207 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1208 	/* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
1209 	 * message to the selected DHT candidates
1210 	 */
1211 	if (type != ARPOP_REQUEST)
1212 		goto out;
1213 
1214 	batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
1215 
1216 	ip_src = batadv_arp_ip_src(skb, hdr_size);
1217 	hw_src = batadv_arp_hw_src(skb, hdr_size);
1218 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1219 
1220 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1221 
1222 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1223 	if (dat_entry) {
1224 		/* If the ARP request is destined for a local client the local
1225 		 * client will answer itself. DAT would only generate a
1226 		 * duplicate packet.
1227 		 *
1228 		 * Moreover, if the soft-interface is enslaved into a bridge, an
1229 		 * additional DAT answer may trigger kernel warnings about
1230 		 * a packet coming from the wrong port.
1231 		 */
1232 		if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
1233 			ret = true;
1234 			goto out;
1235 		}
1236 
1237 		/* If BLA is enabled, only send ARP replies if we have claimed
1238 		 * the destination for the ARP request or if no one else of
1239 		 * the backbone gws belonging to our backbone has claimed the
1240 		 * destination.
1241 		 */
1242 		if (!batadv_bla_check_claim(bat_priv,
1243 					    dat_entry->mac_addr, vid)) {
1244 			batadv_dbg(BATADV_DBG_DAT, bat_priv,
1245 				   "Device %pM claimed by another backbone gw. Don't send ARP reply!",
1246 				   dat_entry->mac_addr);
1247 			ret = true;
1248 			goto out;
1249 		}
1250 
1251 		skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1252 						      dat_entry->mac_addr,
1253 						      hw_src, vid);
1254 		if (!skb_new)
1255 			goto out;
1256 
1257 		skb_new->protocol = eth_type_trans(skb_new, soft_iface);
1258 
1259 		batadv_inc_counter(bat_priv, BATADV_CNT_RX);
1260 		batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
1261 				   skb->len + ETH_HLEN + hdr_size);
1262 
1263 		netif_rx(skb_new);
1264 		batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
1265 		ret = true;
1266 	} else {
1267 		/* Send the request to the DHT */
1268 		ret = batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1269 					      BATADV_P_DAT_DHT_GET);
1270 	}
1271 out:
1272 	if (dat_entry)
1273 		batadv_dat_entry_put(dat_entry);
1274 	return ret;
1275 }
1276 
1277 /**
1278  * batadv_dat_snoop_incoming_arp_request() - snoop the ARP request and try to
1279  * answer using the local DAT storage
1280  * @bat_priv: the bat priv with all the soft interface information
1281  * @skb: packet to check
1282  * @hdr_size: size of the encapsulation header
1283  *
1284  * Return: true if the request has been answered, false otherwise.
1285  */
1286 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
1287 					   struct sk_buff *skb, int hdr_size)
1288 {
1289 	u16 type;
1290 	__be32 ip_src, ip_dst;
1291 	u8 *hw_src;
1292 	struct sk_buff *skb_new;
1293 	struct batadv_dat_entry *dat_entry = NULL;
1294 	bool ret = false;
1295 	unsigned short vid;
1296 	int err;
1297 
1298 	if (!atomic_read(&bat_priv->distributed_arp_table))
1299 		goto out;
1300 
1301 	vid = batadv_dat_get_vid(skb, &hdr_size);
1302 
1303 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1304 	if (type != ARPOP_REQUEST)
1305 		goto out;
1306 
1307 	hw_src = batadv_arp_hw_src(skb, hdr_size);
1308 	ip_src = batadv_arp_ip_src(skb, hdr_size);
1309 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1310 
1311 	batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
1312 
1313 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1314 
1315 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1316 	if (!dat_entry)
1317 		goto out;
1318 
1319 	skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1320 					      dat_entry->mac_addr, hw_src, vid);
1321 	if (!skb_new)
1322 		goto out;
1323 
1324 	/* To preserve backwards compatibility, the node has choose the outgoing
1325 	 * format based on the incoming request packet type. The assumption is
1326 	 * that a node not using the 4addr packet format doesn't support it.
1327 	 */
1328 	if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1329 		err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1330 						   BATADV_P_DAT_CACHE_REPLY,
1331 						   NULL, vid);
1332 	else
1333 		err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1334 
1335 	if (err != NET_XMIT_DROP) {
1336 		batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1337 		ret = true;
1338 	}
1339 out:
1340 	if (dat_entry)
1341 		batadv_dat_entry_put(dat_entry);
1342 	if (ret)
1343 		kfree_skb(skb);
1344 	return ret;
1345 }
1346 
1347 /**
1348  * batadv_dat_snoop_outgoing_arp_reply() - snoop the ARP reply and fill the DHT
1349  * @bat_priv: the bat priv with all the soft interface information
1350  * @skb: packet to check
1351  */
1352 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1353 					 struct sk_buff *skb)
1354 {
1355 	u16 type;
1356 	__be32 ip_src, ip_dst;
1357 	u8 *hw_src, *hw_dst;
1358 	int hdr_size = 0;
1359 	unsigned short vid;
1360 
1361 	if (!atomic_read(&bat_priv->distributed_arp_table))
1362 		return;
1363 
1364 	vid = batadv_dat_get_vid(skb, &hdr_size);
1365 
1366 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1367 	if (type != ARPOP_REPLY)
1368 		return;
1369 
1370 	batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
1371 
1372 	hw_src = batadv_arp_hw_src(skb, hdr_size);
1373 	ip_src = batadv_arp_ip_src(skb, hdr_size);
1374 	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1375 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1376 
1377 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1378 	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1379 
1380 	/* Send the ARP reply to the candidates for both the IP addresses that
1381 	 * the node obtained from the ARP reply
1382 	 */
1383 	batadv_dat_forward_data(bat_priv, skb, ip_src, vid,
1384 				BATADV_P_DAT_DHT_PUT);
1385 	batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1386 				BATADV_P_DAT_DHT_PUT);
1387 }
1388 
1389 /**
1390  * batadv_dat_snoop_incoming_arp_reply() - snoop the ARP reply and fill the
1391  *  local DAT storage only
1392  * @bat_priv: the bat priv with all the soft interface information
1393  * @skb: packet to check
1394  * @hdr_size: size of the encapsulation header
1395  *
1396  * Return: true if the packet was snooped and consumed by DAT. False if the
1397  * packet has to be delivered to the interface
1398  */
1399 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1400 					 struct sk_buff *skb, int hdr_size)
1401 {
1402 	struct batadv_dat_entry *dat_entry = NULL;
1403 	u16 type;
1404 	__be32 ip_src, ip_dst;
1405 	u8 *hw_src, *hw_dst;
1406 	bool dropped = false;
1407 	unsigned short vid;
1408 
1409 	if (!atomic_read(&bat_priv->distributed_arp_table))
1410 		goto out;
1411 
1412 	vid = batadv_dat_get_vid(skb, &hdr_size);
1413 
1414 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1415 	if (type != ARPOP_REPLY)
1416 		goto out;
1417 
1418 	batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
1419 
1420 	hw_src = batadv_arp_hw_src(skb, hdr_size);
1421 	ip_src = batadv_arp_ip_src(skb, hdr_size);
1422 	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1423 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1424 
1425 	/* If ip_dst is already in cache and has the right mac address,
1426 	 * drop this frame if this ARP reply is destined for us because it's
1427 	 * most probably an ARP reply generated by another node of the DHT.
1428 	 * We have most probably received already a reply earlier. Delivering
1429 	 * this frame would lead to doubled receive of an ARP reply.
1430 	 */
1431 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
1432 	if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
1433 		batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
1434 			   hw_src, &ip_src, hw_dst, &ip_dst,
1435 			   dat_entry->mac_addr,	&dat_entry->ip);
1436 		dropped = true;
1437 	}
1438 
1439 	/* Update our internal cache with both the IP addresses the node got
1440 	 * within the ARP reply
1441 	 */
1442 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1443 	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1444 
1445 	if (dropped)
1446 		goto out;
1447 
1448 	/* If BLA is enabled, only forward ARP replies if we have claimed the
1449 	 * source of the ARP reply or if no one else of the same backbone has
1450 	 * already claimed that client. This prevents that different gateways
1451 	 * to the same backbone all forward the ARP reply leading to multiple
1452 	 * replies in the backbone.
1453 	 */
1454 	if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
1455 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
1456 			   "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
1457 			   hw_src);
1458 		dropped = true;
1459 		goto out;
1460 	}
1461 
1462 	/* if this REPLY is directed to a client of mine, let's deliver the
1463 	 * packet to the interface
1464 	 */
1465 	dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
1466 
1467 	/* if this REPLY is sent on behalf of a client of mine, let's drop the
1468 	 * packet because the client will reply by itself
1469 	 */
1470 	dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
1471 out:
1472 	if (dropped)
1473 		kfree_skb(skb);
1474 	if (dat_entry)
1475 		batadv_dat_entry_put(dat_entry);
1476 	/* if dropped == false -> deliver to the interface */
1477 	return dropped;
1478 }
1479 
1480 /**
1481  * batadv_dat_check_dhcp_ipudp() - check skb for IP+UDP headers valid for DHCP
1482  * @skb: the packet to check
1483  * @ip_src: a buffer to store the IPv4 source address in
1484  *
1485  * Checks whether the given skb has an IP and UDP header valid for a DHCP
1486  * message from a DHCP server. And if so, stores the IPv4 source address in
1487  * the provided buffer.
1488  *
1489  * Return: True if valid, false otherwise.
1490  */
1491 static bool
1492 batadv_dat_check_dhcp_ipudp(struct sk_buff *skb, __be32 *ip_src)
1493 {
1494 	unsigned int offset = skb_network_offset(skb);
1495 	struct udphdr *udphdr, _udphdr;
1496 	struct iphdr *iphdr, _iphdr;
1497 
1498 	iphdr = skb_header_pointer(skb, offset, sizeof(_iphdr), &_iphdr);
1499 	if (!iphdr || iphdr->version != 4 || iphdr->ihl * 4 < sizeof(_iphdr))
1500 		return false;
1501 
1502 	if (iphdr->protocol != IPPROTO_UDP)
1503 		return false;
1504 
1505 	offset += iphdr->ihl * 4;
1506 	skb_set_transport_header(skb, offset);
1507 
1508 	udphdr = skb_header_pointer(skb, offset, sizeof(_udphdr), &_udphdr);
1509 	if (!udphdr || udphdr->source != htons(67))
1510 		return false;
1511 
1512 	*ip_src = get_unaligned(&iphdr->saddr);
1513 
1514 	return true;
1515 }
1516 
1517 /**
1518  * batadv_dat_check_dhcp() - examine packet for valid DHCP message
1519  * @skb: the packet to check
1520  * @proto: ethernet protocol hint (behind a potential vlan)
1521  * @ip_src: a buffer to store the IPv4 source address in
1522  *
1523  * Checks whether the given skb is a valid DHCP packet. And if so, stores the
1524  * IPv4 source address in the provided buffer.
1525  *
1526  * Caller needs to ensure that the skb network header is set correctly.
1527  *
1528  * Return: If skb is a valid DHCP packet, then returns its op code
1529  * (e.g. BOOTREPLY vs. BOOTREQUEST). Otherwise returns -EINVAL.
1530  */
1531 static int
1532 batadv_dat_check_dhcp(struct sk_buff *skb, __be16 proto, __be32 *ip_src)
1533 {
1534 	__be32 *magic, _magic;
1535 	unsigned int offset;
1536 	struct {
1537 		__u8 op;
1538 		__u8 htype;
1539 		__u8 hlen;
1540 		__u8 hops;
1541 	} *dhcp_h, _dhcp_h;
1542 
1543 	if (proto != htons(ETH_P_IP))
1544 		return -EINVAL;
1545 
1546 	if (!batadv_dat_check_dhcp_ipudp(skb, ip_src))
1547 		return -EINVAL;
1548 
1549 	offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1550 	if (skb->len < offset + sizeof(struct batadv_dhcp_packet))
1551 		return -EINVAL;
1552 
1553 	dhcp_h = skb_header_pointer(skb, offset, sizeof(_dhcp_h), &_dhcp_h);
1554 	if (!dhcp_h || dhcp_h->htype != BATADV_HTYPE_ETHERNET ||
1555 	    dhcp_h->hlen != ETH_ALEN)
1556 		return -EINVAL;
1557 
1558 	offset += offsetof(struct batadv_dhcp_packet, magic);
1559 
1560 	magic = skb_header_pointer(skb, offset, sizeof(_magic), &_magic);
1561 	if (!magic || get_unaligned(magic) != htonl(BATADV_DHCP_MAGIC))
1562 		return -EINVAL;
1563 
1564 	return dhcp_h->op;
1565 }
1566 
1567 /**
1568  * batadv_dat_get_dhcp_message_type() - get message type of a DHCP packet
1569  * @skb: the DHCP packet to parse
1570  *
1571  * Iterates over the DHCP options of the given DHCP packet to find a
1572  * DHCP Message Type option and parse it.
1573  *
1574  * Caller needs to ensure that the given skb is a valid DHCP packet and
1575  * that the skb transport header is set correctly.
1576  *
1577  * Return: The found DHCP message type value, if found. -EINVAL otherwise.
1578  */
1579 static int batadv_dat_get_dhcp_message_type(struct sk_buff *skb)
1580 {
1581 	unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1582 	u8 *type, _type;
1583 	struct {
1584 		u8 type;
1585 		u8 len;
1586 	} *tl, _tl;
1587 
1588 	offset += sizeof(struct batadv_dhcp_packet);
1589 
1590 	while ((tl = skb_header_pointer(skb, offset, sizeof(_tl), &_tl))) {
1591 		if (tl->type == BATADV_DHCP_OPT_MSG_TYPE)
1592 			break;
1593 
1594 		if (tl->type == BATADV_DHCP_OPT_END)
1595 			break;
1596 
1597 		if (tl->type == BATADV_DHCP_OPT_PAD)
1598 			offset++;
1599 		else
1600 			offset += tl->len + sizeof(_tl);
1601 	}
1602 
1603 	/* Option Overload Code not supported */
1604 	if (!tl || tl->type != BATADV_DHCP_OPT_MSG_TYPE ||
1605 	    tl->len != sizeof(_type))
1606 		return -EINVAL;
1607 
1608 	offset += sizeof(_tl);
1609 
1610 	type = skb_header_pointer(skb, offset, sizeof(_type), &_type);
1611 	if (!type)
1612 		return -EINVAL;
1613 
1614 	return *type;
1615 }
1616 
1617 /**
1618  * batadv_dat_get_dhcp_yiaddr() - get yiaddr from a DHCP packet
1619  * @skb: the DHCP packet to parse
1620  * @buf: a buffer to store the yiaddr in
1621  *
1622  * Caller needs to ensure that the given skb is a valid DHCP packet and
1623  * that the skb transport header is set correctly.
1624  *
1625  * Return: True on success, false otherwise.
1626  */
1627 static bool batadv_dat_dhcp_get_yiaddr(struct sk_buff *skb, __be32 *buf)
1628 {
1629 	unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1630 	__be32 *yiaddr;
1631 
1632 	offset += offsetof(struct batadv_dhcp_packet, yiaddr);
1633 	yiaddr = skb_header_pointer(skb, offset, BATADV_DHCP_YIADDR_LEN, buf);
1634 
1635 	if (!yiaddr)
1636 		return false;
1637 
1638 	if (yiaddr != buf)
1639 		*buf = get_unaligned(yiaddr);
1640 
1641 	return true;
1642 }
1643 
1644 /**
1645  * batadv_dat_get_dhcp_chaddr() - get chaddr from a DHCP packet
1646  * @skb: the DHCP packet to parse
1647  * @buf: a buffer to store the chaddr in
1648  *
1649  * Caller needs to ensure that the given skb is a valid DHCP packet and
1650  * that the skb transport header is set correctly.
1651  *
1652  * Return: True on success, false otherwise
1653  */
1654 static bool batadv_dat_get_dhcp_chaddr(struct sk_buff *skb, u8 *buf)
1655 {
1656 	unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1657 	u8 *chaddr;
1658 
1659 	offset += offsetof(struct batadv_dhcp_packet, chaddr);
1660 	chaddr = skb_header_pointer(skb, offset, BATADV_DHCP_CHADDR_LEN, buf);
1661 
1662 	if (!chaddr)
1663 		return false;
1664 
1665 	if (chaddr != buf)
1666 		memcpy(buf, chaddr, BATADV_DHCP_CHADDR_LEN);
1667 
1668 	return true;
1669 }
1670 
1671 /**
1672  * batadv_dat_put_dhcp() - puts addresses from a DHCP packet into the DHT and
1673  *  DAT cache
1674  * @bat_priv: the bat priv with all the soft interface information
1675  * @chaddr: the DHCP client MAC address
1676  * @yiaddr: the DHCP client IP address
1677  * @hw_dst: the DHCP server MAC address
1678  * @ip_dst: the DHCP server IP address
1679  * @vid: VLAN identifier
1680  *
1681  * Adds given MAC/IP pairs to the local DAT cache and propagates them further
1682  * into the DHT.
1683  *
1684  * For the DHT propagation, client MAC + IP will appear as the ARP Reply
1685  * transmitter (and hw_dst/ip_dst as the target).
1686  */
1687 static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
1688 				__be32 yiaddr, u8 *hw_dst, __be32 ip_dst,
1689 				unsigned short vid)
1690 {
1691 	struct sk_buff *skb;
1692 
1693 	skb = batadv_dat_arp_create_reply(bat_priv, yiaddr, ip_dst, chaddr,
1694 					  hw_dst, vid);
1695 	if (!skb)
1696 		return;
1697 
1698 	skb_set_network_header(skb, ETH_HLEN);
1699 
1700 	batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1701 	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1702 
1703 	batadv_dat_forward_data(bat_priv, skb, yiaddr, vid,
1704 				BATADV_P_DAT_DHT_PUT);
1705 	batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1706 				BATADV_P_DAT_DHT_PUT);
1707 
1708 	consume_skb(skb);
1709 
1710 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
1711 		   "Snooped from outgoing DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1712 		   &ip_dst, hw_dst, batadv_print_vid(vid));
1713 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
1714 		   "Snooped from outgoing DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1715 		   &yiaddr, chaddr, batadv_print_vid(vid));
1716 }
1717 
1718 /**
1719  * batadv_dat_check_dhcp_ack() - examine packet for valid DHCP message
1720  * @skb: the packet to check
1721  * @proto: ethernet protocol hint (behind a potential vlan)
1722  * @ip_src: a buffer to store the IPv4 source address in
1723  * @chaddr: a buffer to store the DHCP Client Hardware Address in
1724  * @yiaddr: a buffer to store the DHCP Your IP Address in
1725  *
1726  * Checks whether the given skb is a valid DHCPACK. And if so, stores the
1727  * IPv4 server source address (ip_src), client MAC address (chaddr) and client
1728  * IPv4 address (yiaddr) in the provided buffers.
1729  *
1730  * Caller needs to ensure that the skb network header is set correctly.
1731  *
1732  * Return: True if the skb is a valid DHCPACK. False otherwise.
1733  */
1734 static bool
1735 batadv_dat_check_dhcp_ack(struct sk_buff *skb, __be16 proto, __be32 *ip_src,
1736 			  u8 *chaddr, __be32 *yiaddr)
1737 {
1738 	int type;
1739 
1740 	type = batadv_dat_check_dhcp(skb, proto, ip_src);
1741 	if (type != BATADV_BOOTREPLY)
1742 		return false;
1743 
1744 	type = batadv_dat_get_dhcp_message_type(skb);
1745 	if (type != BATADV_DHCPACK)
1746 		return false;
1747 
1748 	if (!batadv_dat_dhcp_get_yiaddr(skb, yiaddr))
1749 		return false;
1750 
1751 	if (!batadv_dat_get_dhcp_chaddr(skb, chaddr))
1752 		return false;
1753 
1754 	return true;
1755 }
1756 
1757 /**
1758  * batadv_dat_snoop_outgoing_dhcp_ack() - snoop DHCPACK and fill DAT with it
1759  * @bat_priv: the bat priv with all the soft interface information
1760  * @skb: the packet to snoop
1761  * @proto: ethernet protocol hint (behind a potential vlan)
1762  * @vid: VLAN identifier
1763  *
1764  * This function first checks whether the given skb is a valid DHCPACK. If
1765  * so then its source MAC and IP as well as its DHCP Client Hardware Address
1766  * field and DHCP Your IP Address field are added to the local DAT cache and
1767  * propagated into the DHT.
1768  *
1769  * Caller needs to ensure that the skb mac and network headers are set
1770  * correctly.
1771  */
1772 void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
1773 					struct sk_buff *skb,
1774 					__be16 proto,
1775 					unsigned short vid)
1776 {
1777 	u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1778 	__be32 ip_src, yiaddr;
1779 
1780 	if (!atomic_read(&bat_priv->distributed_arp_table))
1781 		return;
1782 
1783 	if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1784 		return;
1785 
1786 	batadv_dat_put_dhcp(bat_priv, chaddr, yiaddr, eth_hdr(skb)->h_source,
1787 			    ip_src, vid);
1788 }
1789 
1790 /**
1791  * batadv_dat_snoop_incoming_dhcp_ack() - snoop DHCPACK and fill DAT cache
1792  * @bat_priv: the bat priv with all the soft interface information
1793  * @skb: the packet to snoop
1794  * @hdr_size: header size, up to the tail of the batman-adv header
1795  *
1796  * This function first checks whether the given skb is a valid DHCPACK. If
1797  * so then its source MAC and IP as well as its DHCP Client Hardware Address
1798  * field and DHCP Your IP Address field are added to the local DAT cache.
1799  */
1800 void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
1801 					struct sk_buff *skb, int hdr_size)
1802 {
1803 	u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1804 	struct ethhdr *ethhdr;
1805 	__be32 ip_src, yiaddr;
1806 	unsigned short vid;
1807 	__be16 proto;
1808 	u8 *hw_src;
1809 
1810 	if (!atomic_read(&bat_priv->distributed_arp_table))
1811 		return;
1812 
1813 	if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1814 		return;
1815 
1816 	ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1817 	skb_set_network_header(skb, hdr_size + ETH_HLEN);
1818 	proto = ethhdr->h_proto;
1819 
1820 	if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1821 		return;
1822 
1823 	hw_src = ethhdr->h_source;
1824 	vid = batadv_dat_get_vid(skb, &hdr_size);
1825 
1826 	batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1827 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1828 
1829 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
1830 		   "Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1831 		   &ip_src, hw_src, batadv_print_vid(vid));
1832 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
1833 		   "Snooped from incoming DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1834 		   &yiaddr, chaddr, batadv_print_vid(vid));
1835 }
1836 
1837 /**
1838  * batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
1839  *  dropped (because the node has already obtained the reply via DAT) or not
1840  * @bat_priv: the bat priv with all the soft interface information
1841  * @forw_packet: the broadcast packet
1842  *
1843  * Return: true if the node can drop the packet, false otherwise.
1844  */
1845 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1846 				      struct batadv_forw_packet *forw_packet)
1847 {
1848 	u16 type;
1849 	__be32 ip_dst;
1850 	struct batadv_dat_entry *dat_entry = NULL;
1851 	bool ret = false;
1852 	int hdr_size = sizeof(struct batadv_bcast_packet);
1853 	unsigned short vid;
1854 
1855 	if (!atomic_read(&bat_priv->distributed_arp_table))
1856 		goto out;
1857 
1858 	/* If this packet is an ARP_REQUEST and the node already has the
1859 	 * information that it is going to ask, then the packet can be dropped
1860 	 */
1861 	if (batadv_forw_packet_is_rebroadcast(forw_packet))
1862 		goto out;
1863 
1864 	vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1865 
1866 	type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1867 	if (type != ARPOP_REQUEST)
1868 		goto out;
1869 
1870 	ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1871 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1872 	/* check if the node already got this entry */
1873 	if (!dat_entry) {
1874 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
1875 			   "ARP Request for %pI4: fallback\n", &ip_dst);
1876 		goto out;
1877 	}
1878 
1879 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
1880 		   "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1881 	ret = true;
1882 
1883 out:
1884 	if (dat_entry)
1885 		batadv_dat_entry_put(dat_entry);
1886 	return ret;
1887 }
1888