1 /* Copyright (C) 2012-2017  B.A.T.M.A.N. contributors:
2  *
3  * Martin Hundebøll, Jeppe Ledet-Pedersen
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 "network-coding.h"
19 #include "main.h"
20 
21 #include <linux/atomic.h>
22 #include <linux/bitops.h>
23 #include <linux/byteorder/generic.h>
24 #include <linux/compiler.h>
25 #include <linux/debugfs.h>
26 #include <linux/errno.h>
27 #include <linux/etherdevice.h>
28 #include <linux/fs.h>
29 #include <linux/if_ether.h>
30 #include <linux/if_packet.h>
31 #include <linux/init.h>
32 #include <linux/jhash.h>
33 #include <linux/jiffies.h>
34 #include <linux/kernel.h>
35 #include <linux/kref.h>
36 #include <linux/list.h>
37 #include <linux/lockdep.h>
38 #include <linux/netdevice.h>
39 #include <linux/printk.h>
40 #include <linux/random.h>
41 #include <linux/rculist.h>
42 #include <linux/rcupdate.h>
43 #include <linux/seq_file.h>
44 #include <linux/skbuff.h>
45 #include <linux/slab.h>
46 #include <linux/spinlock.h>
47 #include <linux/stddef.h>
48 #include <linux/string.h>
49 #include <linux/workqueue.h>
50 
51 #include "hard-interface.h"
52 #include "hash.h"
53 #include "log.h"
54 #include "originator.h"
55 #include "packet.h"
56 #include "routing.h"
57 #include "send.h"
58 #include "tvlv.h"
59 
60 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
61 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
62 
63 static void batadv_nc_worker(struct work_struct *work);
64 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
65 				       struct batadv_hard_iface *recv_if);
66 
67 /**
68  * batadv_nc_init - one-time initialization for network coding
69  *
70  * Return: 0 on success or negative error number in case of failure
71  */
72 int __init batadv_nc_init(void)
73 {
74 	int ret;
75 
76 	/* Register our packet type */
77 	ret = batadv_recv_handler_register(BATADV_CODED,
78 					   batadv_nc_recv_coded_packet);
79 
80 	return ret;
81 }
82 
83 /**
84  * batadv_nc_start_timer - initialise the nc periodic worker
85  * @bat_priv: the bat priv with all the soft interface information
86  */
87 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
88 {
89 	queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
90 			   msecs_to_jiffies(10));
91 }
92 
93 /**
94  * batadv_nc_tvlv_container_update - update the network coding tvlv container
95  *  after network coding setting change
96  * @bat_priv: the bat priv with all the soft interface information
97  */
98 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
99 {
100 	char nc_mode;
101 
102 	nc_mode = atomic_read(&bat_priv->network_coding);
103 
104 	switch (nc_mode) {
105 	case 0:
106 		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
107 		break;
108 	case 1:
109 		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
110 					       NULL, 0);
111 		break;
112 	}
113 }
114 
115 /**
116  * batadv_nc_status_update - update the network coding tvlv container after
117  *  network coding setting change
118  * @net_dev: the soft interface net device
119  */
120 void batadv_nc_status_update(struct net_device *net_dev)
121 {
122 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
123 
124 	batadv_nc_tvlv_container_update(bat_priv);
125 }
126 
127 /**
128  * batadv_nc_tvlv_ogm_handler_v1 - process incoming nc tvlv container
129  * @bat_priv: the bat priv with all the soft interface information
130  * @orig: the orig_node of the ogm
131  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
132  * @tvlv_value: tvlv buffer containing the gateway data
133  * @tvlv_value_len: tvlv buffer length
134  */
135 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
136 					  struct batadv_orig_node *orig,
137 					  u8 flags,
138 					  void *tvlv_value, u16 tvlv_value_len)
139 {
140 	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
141 		clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
142 	else
143 		set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
144 }
145 
146 /**
147  * batadv_nc_mesh_init - initialise coding hash table and start house keeping
148  * @bat_priv: the bat priv with all the soft interface information
149  *
150  * Return: 0 on success or negative error number in case of failure
151  */
152 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
153 {
154 	bat_priv->nc.timestamp_fwd_flush = jiffies;
155 	bat_priv->nc.timestamp_sniffed_purge = jiffies;
156 
157 	if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
158 		return 0;
159 
160 	bat_priv->nc.coding_hash = batadv_hash_new(128);
161 	if (!bat_priv->nc.coding_hash)
162 		goto err;
163 
164 	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
165 				   &batadv_nc_coding_hash_lock_class_key);
166 
167 	bat_priv->nc.decoding_hash = batadv_hash_new(128);
168 	if (!bat_priv->nc.decoding_hash)
169 		goto err;
170 
171 	batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
172 				   &batadv_nc_decoding_hash_lock_class_key);
173 
174 	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
175 	batadv_nc_start_timer(bat_priv);
176 
177 	batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
178 				     NULL, BATADV_TVLV_NC, 1,
179 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
180 	batadv_nc_tvlv_container_update(bat_priv);
181 	return 0;
182 
183 err:
184 	return -ENOMEM;
185 }
186 
187 /**
188  * batadv_nc_init_bat_priv - initialise the nc specific bat_priv variables
189  * @bat_priv: the bat priv with all the soft interface information
190  */
191 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
192 {
193 	atomic_set(&bat_priv->network_coding, 0);
194 	bat_priv->nc.min_tq = 200;
195 	bat_priv->nc.max_fwd_delay = 10;
196 	bat_priv->nc.max_buffer_time = 200;
197 }
198 
199 /**
200  * batadv_nc_init_orig - initialise the nc fields of an orig_node
201  * @orig_node: the orig_node which is going to be initialised
202  */
203 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
204 {
205 	INIT_LIST_HEAD(&orig_node->in_coding_list);
206 	INIT_LIST_HEAD(&orig_node->out_coding_list);
207 	spin_lock_init(&orig_node->in_coding_list_lock);
208 	spin_lock_init(&orig_node->out_coding_list_lock);
209 }
210 
211 /**
212  * batadv_nc_node_release - release nc_node from lists and queue for free after
213  *  rcu grace period
214  * @ref: kref pointer of the nc_node
215  */
216 static void batadv_nc_node_release(struct kref *ref)
217 {
218 	struct batadv_nc_node *nc_node;
219 
220 	nc_node = container_of(ref, struct batadv_nc_node, refcount);
221 
222 	batadv_orig_node_put(nc_node->orig_node);
223 	kfree_rcu(nc_node, rcu);
224 }
225 
226 /**
227  * batadv_nc_node_put - decrement the nc_node refcounter and possibly
228  *  release it
229  * @nc_node: nc_node to be free'd
230  */
231 static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
232 {
233 	kref_put(&nc_node->refcount, batadv_nc_node_release);
234 }
235 
236 /**
237  * batadv_nc_path_release - release nc_path from lists and queue for free after
238  *  rcu grace period
239  * @ref: kref pointer of the nc_path
240  */
241 static void batadv_nc_path_release(struct kref *ref)
242 {
243 	struct batadv_nc_path *nc_path;
244 
245 	nc_path = container_of(ref, struct batadv_nc_path, refcount);
246 
247 	kfree_rcu(nc_path, rcu);
248 }
249 
250 /**
251  * batadv_nc_path_put - decrement the nc_path refcounter and possibly
252  *  release it
253  * @nc_path: nc_path to be free'd
254  */
255 static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
256 {
257 	kref_put(&nc_path->refcount, batadv_nc_path_release);
258 }
259 
260 /**
261  * batadv_nc_packet_free - frees nc packet
262  * @nc_packet: the nc packet to free
263  * @dropped: whether the packet is freed because is is dropped
264  */
265 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
266 				  bool dropped)
267 {
268 	if (dropped)
269 		kfree_skb(nc_packet->skb);
270 	else
271 		consume_skb(nc_packet->skb);
272 
273 	batadv_nc_path_put(nc_packet->nc_path);
274 	kfree(nc_packet);
275 }
276 
277 /**
278  * batadv_nc_to_purge_nc_node - checks whether an nc node has to be purged
279  * @bat_priv: the bat priv with all the soft interface information
280  * @nc_node: the nc node to check
281  *
282  * Return: true if the entry has to be purged now, false otherwise
283  */
284 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
285 				       struct batadv_nc_node *nc_node)
286 {
287 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
288 		return true;
289 
290 	return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
291 }
292 
293 /**
294  * batadv_nc_to_purge_nc_path_coding - checks whether an nc path has timed out
295  * @bat_priv: the bat priv with all the soft interface information
296  * @nc_path: the nc path to check
297  *
298  * Return: true if the entry has to be purged now, false otherwise
299  */
300 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
301 					      struct batadv_nc_path *nc_path)
302 {
303 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
304 		return true;
305 
306 	/* purge the path when no packets has been added for 10 times the
307 	 * max_fwd_delay time
308 	 */
309 	return batadv_has_timed_out(nc_path->last_valid,
310 				    bat_priv->nc.max_fwd_delay * 10);
311 }
312 
313 /**
314  * batadv_nc_to_purge_nc_path_decoding - checks whether an nc path has timed out
315  * @bat_priv: the bat priv with all the soft interface information
316  * @nc_path: the nc path to check
317  *
318  * Return: true if the entry has to be purged now, false otherwise
319  */
320 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
321 						struct batadv_nc_path *nc_path)
322 {
323 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
324 		return true;
325 
326 	/* purge the path when no packets has been added for 10 times the
327 	 * max_buffer time
328 	 */
329 	return batadv_has_timed_out(nc_path->last_valid,
330 				    bat_priv->nc.max_buffer_time * 10);
331 }
332 
333 /**
334  * batadv_nc_purge_orig_nc_nodes - go through list of nc nodes and purge stale
335  *  entries
336  * @bat_priv: the bat priv with all the soft interface information
337  * @list: list of nc nodes
338  * @lock: nc node list lock
339  * @to_purge: function in charge to decide whether an entry has to be purged or
340  *	      not. This function takes the nc node as argument and has to return
341  *	      a boolean value: true if the entry has to be deleted, false
342  *	      otherwise
343  */
344 static void
345 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
346 			      struct list_head *list,
347 			      spinlock_t *lock,
348 			      bool (*to_purge)(struct batadv_priv *,
349 					       struct batadv_nc_node *))
350 {
351 	struct batadv_nc_node *nc_node, *nc_node_tmp;
352 
353 	/* For each nc_node in list */
354 	spin_lock_bh(lock);
355 	list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
356 		/* if an helper function has been passed as parameter,
357 		 * ask it if the entry has to be purged or not
358 		 */
359 		if (to_purge && !to_purge(bat_priv, nc_node))
360 			continue;
361 
362 		batadv_dbg(BATADV_DBG_NC, bat_priv,
363 			   "Removing nc_node %pM -> %pM\n",
364 			   nc_node->addr, nc_node->orig_node->orig);
365 		list_del_rcu(&nc_node->list);
366 		batadv_nc_node_put(nc_node);
367 	}
368 	spin_unlock_bh(lock);
369 }
370 
371 /**
372  * batadv_nc_purge_orig - purges all nc node data attached of the given
373  *  originator
374  * @bat_priv: the bat priv with all the soft interface information
375  * @orig_node: orig_node with the nc node entries to be purged
376  * @to_purge: function in charge to decide whether an entry has to be purged or
377  *	      not. This function takes the nc node as argument and has to return
378  *	      a boolean value: true is the entry has to be deleted, false
379  *	      otherwise
380  */
381 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
382 			  struct batadv_orig_node *orig_node,
383 			  bool (*to_purge)(struct batadv_priv *,
384 					   struct batadv_nc_node *))
385 {
386 	/* Check ingoing nc_node's of this orig_node */
387 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
388 				      &orig_node->in_coding_list_lock,
389 				      to_purge);
390 
391 	/* Check outgoing nc_node's of this orig_node */
392 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
393 				      &orig_node->out_coding_list_lock,
394 				      to_purge);
395 }
396 
397 /**
398  * batadv_nc_purge_orig_hash - traverse entire originator hash to check if they
399  *  have timed out nc nodes
400  * @bat_priv: the bat priv with all the soft interface information
401  */
402 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
403 {
404 	struct batadv_hashtable *hash = bat_priv->orig_hash;
405 	struct hlist_head *head;
406 	struct batadv_orig_node *orig_node;
407 	u32 i;
408 
409 	if (!hash)
410 		return;
411 
412 	/* For each orig_node */
413 	for (i = 0; i < hash->size; i++) {
414 		head = &hash->table[i];
415 
416 		rcu_read_lock();
417 		hlist_for_each_entry_rcu(orig_node, head, hash_entry)
418 			batadv_nc_purge_orig(bat_priv, orig_node,
419 					     batadv_nc_to_purge_nc_node);
420 		rcu_read_unlock();
421 	}
422 }
423 
424 /**
425  * batadv_nc_purge_paths - traverse all nc paths part of the hash and remove
426  *  unused ones
427  * @bat_priv: the bat priv with all the soft interface information
428  * @hash: hash table containing the nc paths to check
429  * @to_purge: function in charge to decide whether an entry has to be purged or
430  *	      not. This function takes the nc node as argument and has to return
431  *	      a boolean value: true is the entry has to be deleted, false
432  *	      otherwise
433  */
434 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
435 				  struct batadv_hashtable *hash,
436 				  bool (*to_purge)(struct batadv_priv *,
437 						   struct batadv_nc_path *))
438 {
439 	struct hlist_head *head;
440 	struct hlist_node *node_tmp;
441 	struct batadv_nc_path *nc_path;
442 	spinlock_t *lock; /* Protects lists in hash */
443 	u32 i;
444 
445 	for (i = 0; i < hash->size; i++) {
446 		head = &hash->table[i];
447 		lock = &hash->list_locks[i];
448 
449 		/* For each nc_path in this bin */
450 		spin_lock_bh(lock);
451 		hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
452 			/* if an helper function has been passed as parameter,
453 			 * ask it if the entry has to be purged or not
454 			 */
455 			if (to_purge && !to_purge(bat_priv, nc_path))
456 				continue;
457 
458 			/* purging an non-empty nc_path should never happen, but
459 			 * is observed under high CPU load. Delay the purging
460 			 * until next iteration to allow the packet_list to be
461 			 * emptied first.
462 			 */
463 			if (!unlikely(list_empty(&nc_path->packet_list))) {
464 				net_ratelimited_function(printk,
465 							 KERN_WARNING
466 							 "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
467 							 nc_path->prev_hop,
468 							 nc_path->next_hop);
469 				continue;
470 			}
471 
472 			/* nc_path is unused, so remove it */
473 			batadv_dbg(BATADV_DBG_NC, bat_priv,
474 				   "Remove nc_path %pM -> %pM\n",
475 				   nc_path->prev_hop, nc_path->next_hop);
476 			hlist_del_rcu(&nc_path->hash_entry);
477 			batadv_nc_path_put(nc_path);
478 		}
479 		spin_unlock_bh(lock);
480 	}
481 }
482 
483 /**
484  * batadv_nc_hash_key_gen - computes the nc_path hash key
485  * @key: buffer to hold the final hash key
486  * @src: source ethernet mac address going into the hash key
487  * @dst: destination ethernet mac address going into the hash key
488  */
489 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
490 				   const char *dst)
491 {
492 	memcpy(key->prev_hop, src, sizeof(key->prev_hop));
493 	memcpy(key->next_hop, dst, sizeof(key->next_hop));
494 }
495 
496 /**
497  * batadv_nc_hash_choose - compute the hash value for an nc path
498  * @data: data to hash
499  * @size: size of the hash table
500  *
501  * Return: the selected index in the hash table for the given data.
502  */
503 static u32 batadv_nc_hash_choose(const void *data, u32 size)
504 {
505 	const struct batadv_nc_path *nc_path = data;
506 	u32 hash = 0;
507 
508 	hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
509 	hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
510 
511 	return hash % size;
512 }
513 
514 /**
515  * batadv_nc_hash_compare - comparing function used in the network coding hash
516  *  tables
517  * @node: node in the local table
518  * @data2: second object to compare the node to
519  *
520  * Return: true if the two entry are the same, false otherwise
521  */
522 static bool batadv_nc_hash_compare(const struct hlist_node *node,
523 				   const void *data2)
524 {
525 	const struct batadv_nc_path *nc_path1, *nc_path2;
526 
527 	nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
528 	nc_path2 = data2;
529 
530 	/* Return 1 if the two keys are identical */
531 	if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
532 		return false;
533 
534 	if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
535 		return false;
536 
537 	return true;
538 }
539 
540 /**
541  * batadv_nc_hash_find - search for an existing nc path and return it
542  * @hash: hash table containing the nc path
543  * @data: search key
544  *
545  * Return: the nc_path if found, NULL otherwise.
546  */
547 static struct batadv_nc_path *
548 batadv_nc_hash_find(struct batadv_hashtable *hash,
549 		    void *data)
550 {
551 	struct hlist_head *head;
552 	struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
553 	int index;
554 
555 	if (!hash)
556 		return NULL;
557 
558 	index = batadv_nc_hash_choose(data, hash->size);
559 	head = &hash->table[index];
560 
561 	rcu_read_lock();
562 	hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
563 		if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
564 			continue;
565 
566 		if (!kref_get_unless_zero(&nc_path->refcount))
567 			continue;
568 
569 		nc_path_tmp = nc_path;
570 		break;
571 	}
572 	rcu_read_unlock();
573 
574 	return nc_path_tmp;
575 }
576 
577 /**
578  * batadv_nc_send_packet - send non-coded packet and free nc_packet struct
579  * @nc_packet: the nc packet to send
580  */
581 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
582 {
583 	batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
584 	nc_packet->skb = NULL;
585 	batadv_nc_packet_free(nc_packet, false);
586 }
587 
588 /**
589  * batadv_nc_sniffed_purge - Checks timestamp of given sniffed nc_packet.
590  * @bat_priv: the bat priv with all the soft interface information
591  * @nc_path: the nc path the packet belongs to
592  * @nc_packet: the nc packet to be checked
593  *
594  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
595  * timeout. If so, the packet is no longer kept and the entry deleted from the
596  * queue. Has to be called with the appropriate locks.
597  *
598  * Return: false as soon as the entry in the fifo queue has not been timed out
599  * yet and true otherwise.
600  */
601 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
602 				    struct batadv_nc_path *nc_path,
603 				    struct batadv_nc_packet *nc_packet)
604 {
605 	unsigned long timeout = bat_priv->nc.max_buffer_time;
606 	bool res = false;
607 
608 	lockdep_assert_held(&nc_path->packet_list_lock);
609 
610 	/* Packets are added to tail, so the remaining packets did not time
611 	 * out and we can stop processing the current queue
612 	 */
613 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
614 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
615 		goto out;
616 
617 	/* purge nc packet */
618 	list_del(&nc_packet->list);
619 	batadv_nc_packet_free(nc_packet, true);
620 
621 	res = true;
622 
623 out:
624 	return res;
625 }
626 
627 /**
628  * batadv_nc_fwd_flush - Checks the timestamp of the given nc packet.
629  * @bat_priv: the bat priv with all the soft interface information
630  * @nc_path: the nc path the packet belongs to
631  * @nc_packet: the nc packet to be checked
632  *
633  * Checks whether the given nc packet has hit its forward timeout. If so, the
634  * packet is no longer delayed, immediately sent and the entry deleted from the
635  * queue. Has to be called with the appropriate locks.
636  *
637  * Return: false as soon as the entry in the fifo queue has not been timed out
638  * yet and true otherwise.
639  */
640 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
641 				struct batadv_nc_path *nc_path,
642 				struct batadv_nc_packet *nc_packet)
643 {
644 	unsigned long timeout = bat_priv->nc.max_fwd_delay;
645 
646 	lockdep_assert_held(&nc_path->packet_list_lock);
647 
648 	/* Packets are added to tail, so the remaining packets did not time
649 	 * out and we can stop processing the current queue
650 	 */
651 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
652 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
653 		return false;
654 
655 	/* Send packet */
656 	batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
657 	batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
658 			   nc_packet->skb->len + ETH_HLEN);
659 	list_del(&nc_packet->list);
660 	batadv_nc_send_packet(nc_packet);
661 
662 	return true;
663 }
664 
665 /**
666  * batadv_nc_process_nc_paths - traverse given nc packet pool and free timed out
667  *  nc packets
668  * @bat_priv: the bat priv with all the soft interface information
669  * @hash: to be processed hash table
670  * @process_fn: Function called to process given nc packet. Should return true
671  *	        to encourage this function to proceed with the next packet.
672  *	        Otherwise the rest of the current queue is skipped.
673  */
674 static void
675 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
676 			   struct batadv_hashtable *hash,
677 			   bool (*process_fn)(struct batadv_priv *,
678 					      struct batadv_nc_path *,
679 					      struct batadv_nc_packet *))
680 {
681 	struct hlist_head *head;
682 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
683 	struct batadv_nc_path *nc_path;
684 	bool ret;
685 	int i;
686 
687 	if (!hash)
688 		return;
689 
690 	/* Loop hash table bins */
691 	for (i = 0; i < hash->size; i++) {
692 		head = &hash->table[i];
693 
694 		/* Loop coding paths */
695 		rcu_read_lock();
696 		hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
697 			/* Loop packets */
698 			spin_lock_bh(&nc_path->packet_list_lock);
699 			list_for_each_entry_safe(nc_packet, nc_packet_tmp,
700 						 &nc_path->packet_list, list) {
701 				ret = process_fn(bat_priv, nc_path, nc_packet);
702 				if (!ret)
703 					break;
704 			}
705 			spin_unlock_bh(&nc_path->packet_list_lock);
706 		}
707 		rcu_read_unlock();
708 	}
709 }
710 
711 /**
712  * batadv_nc_worker - periodic task for house keeping related to network coding
713  * @work: kernel work struct
714  */
715 static void batadv_nc_worker(struct work_struct *work)
716 {
717 	struct delayed_work *delayed_work;
718 	struct batadv_priv_nc *priv_nc;
719 	struct batadv_priv *bat_priv;
720 	unsigned long timeout;
721 
722 	delayed_work = to_delayed_work(work);
723 	priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
724 	bat_priv = container_of(priv_nc, struct batadv_priv, nc);
725 
726 	batadv_nc_purge_orig_hash(bat_priv);
727 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
728 			      batadv_nc_to_purge_nc_path_coding);
729 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
730 			      batadv_nc_to_purge_nc_path_decoding);
731 
732 	timeout = bat_priv->nc.max_fwd_delay;
733 
734 	if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
735 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
736 					   batadv_nc_fwd_flush);
737 		bat_priv->nc.timestamp_fwd_flush = jiffies;
738 	}
739 
740 	if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
741 				 bat_priv->nc.max_buffer_time)) {
742 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
743 					   batadv_nc_sniffed_purge);
744 		bat_priv->nc.timestamp_sniffed_purge = jiffies;
745 	}
746 
747 	/* Schedule a new check */
748 	batadv_nc_start_timer(bat_priv);
749 }
750 
751 /**
752  * batadv_can_nc_with_orig - checks whether the given orig node is suitable for
753  *  coding or not
754  * @bat_priv: the bat priv with all the soft interface information
755  * @orig_node: neighboring orig node which may be used as nc candidate
756  * @ogm_packet: incoming ogm packet also used for the checks
757  *
758  * Return: true if:
759  *  1) The OGM must have the most recent sequence number.
760  *  2) The TTL must be decremented by one and only one.
761  *  3) The OGM must be received from the first hop from orig_node.
762  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
763  */
764 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
765 				    struct batadv_orig_node *orig_node,
766 				    struct batadv_ogm_packet *ogm_packet)
767 {
768 	struct batadv_orig_ifinfo *orig_ifinfo;
769 	u32 last_real_seqno;
770 	u8 last_ttl;
771 
772 	orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
773 	if (!orig_ifinfo)
774 		return false;
775 
776 	last_ttl = orig_ifinfo->last_ttl;
777 	last_real_seqno = orig_ifinfo->last_real_seqno;
778 	batadv_orig_ifinfo_put(orig_ifinfo);
779 
780 	if (last_real_seqno != ntohl(ogm_packet->seqno))
781 		return false;
782 	if (last_ttl != ogm_packet->ttl + 1)
783 		return false;
784 	if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
785 		return false;
786 	if (ogm_packet->tq < bat_priv->nc.min_tq)
787 		return false;
788 
789 	return true;
790 }
791 
792 /**
793  * batadv_nc_find_nc_node - search for an existing nc node and return it
794  * @orig_node: orig node originating the ogm packet
795  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
796  *  (can be equal to orig_node)
797  * @in_coding: traverse incoming or outgoing network coding list
798  *
799  * Return: the nc_node if found, NULL otherwise.
800  */
801 static struct batadv_nc_node *
802 batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
803 		       struct batadv_orig_node *orig_neigh_node,
804 		       bool in_coding)
805 {
806 	struct batadv_nc_node *nc_node, *nc_node_out = NULL;
807 	struct list_head *list;
808 
809 	if (in_coding)
810 		list = &orig_neigh_node->in_coding_list;
811 	else
812 		list = &orig_neigh_node->out_coding_list;
813 
814 	/* Traverse list of nc_nodes to orig_node */
815 	rcu_read_lock();
816 	list_for_each_entry_rcu(nc_node, list, list) {
817 		if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
818 			continue;
819 
820 		if (!kref_get_unless_zero(&nc_node->refcount))
821 			continue;
822 
823 		/* Found a match */
824 		nc_node_out = nc_node;
825 		break;
826 	}
827 	rcu_read_unlock();
828 
829 	return nc_node_out;
830 }
831 
832 /**
833  * batadv_nc_get_nc_node - retrieves an nc node or creates the entry if it was
834  *  not found
835  * @bat_priv: the bat priv with all the soft interface information
836  * @orig_node: orig node originating the ogm packet
837  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
838  *  (can be equal to orig_node)
839  * @in_coding: traverse incoming or outgoing network coding list
840  *
841  * Return: the nc_node if found or created, NULL in case of an error.
842  */
843 static struct batadv_nc_node *
844 batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
845 		      struct batadv_orig_node *orig_node,
846 		      struct batadv_orig_node *orig_neigh_node,
847 		      bool in_coding)
848 {
849 	struct batadv_nc_node *nc_node;
850 	spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
851 	struct list_head *list;
852 
853 	/* Check if nc_node is already added */
854 	nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
855 
856 	/* Node found */
857 	if (nc_node)
858 		return nc_node;
859 
860 	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
861 	if (!nc_node)
862 		return NULL;
863 
864 	/* Initialize nc_node */
865 	INIT_LIST_HEAD(&nc_node->list);
866 	kref_init(&nc_node->refcount);
867 	ether_addr_copy(nc_node->addr, orig_node->orig);
868 	kref_get(&orig_neigh_node->refcount);
869 	nc_node->orig_node = orig_neigh_node;
870 
871 	/* Select ingoing or outgoing coding node */
872 	if (in_coding) {
873 		lock = &orig_neigh_node->in_coding_list_lock;
874 		list = &orig_neigh_node->in_coding_list;
875 	} else {
876 		lock = &orig_neigh_node->out_coding_list_lock;
877 		list = &orig_neigh_node->out_coding_list;
878 	}
879 
880 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
881 		   nc_node->addr, nc_node->orig_node->orig);
882 
883 	/* Add nc_node to orig_node */
884 	spin_lock_bh(lock);
885 	kref_get(&nc_node->refcount);
886 	list_add_tail_rcu(&nc_node->list, list);
887 	spin_unlock_bh(lock);
888 
889 	return nc_node;
890 }
891 
892 /**
893  * batadv_nc_update_nc_node - updates stored incoming and outgoing nc node
894  *  structs (best called on incoming OGMs)
895  * @bat_priv: the bat priv with all the soft interface information
896  * @orig_node: orig node originating the ogm packet
897  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
898  *  (can be equal to orig_node)
899  * @ogm_packet: incoming ogm packet
900  * @is_single_hop_neigh: orig_node is a single hop neighbor
901  */
902 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
903 			      struct batadv_orig_node *orig_node,
904 			      struct batadv_orig_node *orig_neigh_node,
905 			      struct batadv_ogm_packet *ogm_packet,
906 			      int is_single_hop_neigh)
907 {
908 	struct batadv_nc_node *in_nc_node = NULL;
909 	struct batadv_nc_node *out_nc_node = NULL;
910 
911 	/* Check if network coding is enabled */
912 	if (!atomic_read(&bat_priv->network_coding))
913 		goto out;
914 
915 	/* check if orig node is network coding enabled */
916 	if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
917 		goto out;
918 
919 	/* accept ogms from 'good' neighbors and single hop neighbors */
920 	if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
921 	    !is_single_hop_neigh)
922 		goto out;
923 
924 	/* Add orig_node as in_nc_node on hop */
925 	in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
926 					   orig_neigh_node, true);
927 	if (!in_nc_node)
928 		goto out;
929 
930 	in_nc_node->last_seen = jiffies;
931 
932 	/* Add hop as out_nc_node on orig_node */
933 	out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
934 					    orig_node, false);
935 	if (!out_nc_node)
936 		goto out;
937 
938 	out_nc_node->last_seen = jiffies;
939 
940 out:
941 	if (in_nc_node)
942 		batadv_nc_node_put(in_nc_node);
943 	if (out_nc_node)
944 		batadv_nc_node_put(out_nc_node);
945 }
946 
947 /**
948  * batadv_nc_get_path - get existing nc_path or allocate a new one
949  * @bat_priv: the bat priv with all the soft interface information
950  * @hash: hash table containing the nc path
951  * @src: ethernet source address - first half of the nc path search key
952  * @dst: ethernet destination address - second half of the nc path search key
953  *
954  * Return: pointer to nc_path if the path was found or created, returns NULL
955  * on error.
956  */
957 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
958 						 struct batadv_hashtable *hash,
959 						 u8 *src,
960 						 u8 *dst)
961 {
962 	int hash_added;
963 	struct batadv_nc_path *nc_path, nc_path_key;
964 
965 	batadv_nc_hash_key_gen(&nc_path_key, src, dst);
966 
967 	/* Search for existing nc_path */
968 	nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
969 
970 	if (nc_path) {
971 		/* Set timestamp to delay removal of nc_path */
972 		nc_path->last_valid = jiffies;
973 		return nc_path;
974 	}
975 
976 	/* No existing nc_path was found; create a new */
977 	nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
978 
979 	if (!nc_path)
980 		return NULL;
981 
982 	/* Initialize nc_path */
983 	INIT_LIST_HEAD(&nc_path->packet_list);
984 	spin_lock_init(&nc_path->packet_list_lock);
985 	kref_init(&nc_path->refcount);
986 	nc_path->last_valid = jiffies;
987 	ether_addr_copy(nc_path->next_hop, dst);
988 	ether_addr_copy(nc_path->prev_hop, src);
989 
990 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
991 		   nc_path->prev_hop,
992 		   nc_path->next_hop);
993 
994 	/* Add nc_path to hash table */
995 	kref_get(&nc_path->refcount);
996 	hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
997 				     batadv_nc_hash_choose, &nc_path_key,
998 				     &nc_path->hash_entry);
999 
1000 	if (hash_added < 0) {
1001 		kfree(nc_path);
1002 		return NULL;
1003 	}
1004 
1005 	return nc_path;
1006 }
1007 
1008 /**
1009  * batadv_nc_random_weight_tq - scale the receivers TQ-value to avoid unfair
1010  *  selection of a receiver with slightly lower TQ than the other
1011  * @tq: to be weighted tq value
1012  *
1013  * Return: scaled tq value
1014  */
1015 static u8 batadv_nc_random_weight_tq(u8 tq)
1016 {
1017 	u8 rand_val, rand_tq;
1018 
1019 	get_random_bytes(&rand_val, sizeof(rand_val));
1020 
1021 	/* randomize the estimated packet loss (max TQ - estimated TQ) */
1022 	rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
1023 
1024 	/* normalize the randomized packet loss */
1025 	rand_tq /= BATADV_TQ_MAX_VALUE;
1026 
1027 	/* convert to (randomized) estimated tq again */
1028 	return BATADV_TQ_MAX_VALUE - rand_tq;
1029 }
1030 
1031 /**
1032  * batadv_nc_memxor - XOR destination with source
1033  * @dst: byte array to XOR into
1034  * @src: byte array to XOR from
1035  * @len: length of destination array
1036  */
1037 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1038 {
1039 	unsigned int i;
1040 
1041 	for (i = 0; i < len; ++i)
1042 		dst[i] ^= src[i];
1043 }
1044 
1045 /**
1046  * batadv_nc_code_packets - code a received unicast_packet with an nc packet
1047  *  into a coded_packet and send it
1048  * @bat_priv: the bat priv with all the soft interface information
1049  * @skb: data skb to forward
1050  * @ethhdr: pointer to the ethernet header inside the skb
1051  * @nc_packet: structure containing the packet to the skb can be coded with
1052  * @neigh_node: next hop to forward packet to
1053  *
1054  * Return: true if both packets are consumed, false otherwise.
1055  */
1056 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1057 				   struct sk_buff *skb,
1058 				   struct ethhdr *ethhdr,
1059 				   struct batadv_nc_packet *nc_packet,
1060 				   struct batadv_neigh_node *neigh_node)
1061 {
1062 	u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1063 	struct sk_buff *skb_dest, *skb_src;
1064 	struct batadv_unicast_packet *packet1;
1065 	struct batadv_unicast_packet *packet2;
1066 	struct batadv_coded_packet *coded_packet;
1067 	struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1068 	struct batadv_neigh_node *router_coding = NULL, *second_dest;
1069 	struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1070 	struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1071 	u8 *first_source, *second_source;
1072 	__be32 packet_id1, packet_id2;
1073 	size_t count;
1074 	bool res = false;
1075 	int coding_len;
1076 	int unicast_size = sizeof(*packet1);
1077 	int coded_size = sizeof(*coded_packet);
1078 	int header_add = coded_size - unicast_size;
1079 
1080 	/* TODO: do we need to consider the outgoing interface for
1081 	 * coded packets?
1082 	 */
1083 	router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1084 					      BATADV_IF_DEFAULT);
1085 	if (!router_neigh)
1086 		goto out;
1087 
1088 	router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1089 						      BATADV_IF_DEFAULT);
1090 	if (!router_neigh_ifinfo)
1091 		goto out;
1092 
1093 	neigh_tmp = nc_packet->neigh_node;
1094 	router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1095 					       BATADV_IF_DEFAULT);
1096 	if (!router_coding)
1097 		goto out;
1098 
1099 	router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1100 						       BATADV_IF_DEFAULT);
1101 	if (!router_coding_ifinfo)
1102 		goto out;
1103 
1104 	tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1105 	tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1106 	tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1107 	tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1108 
1109 	/* Select one destination for the MAC-header dst-field based on
1110 	 * weighted TQ-values.
1111 	 */
1112 	if (tq_weighted_neigh >= tq_weighted_coding) {
1113 		/* Destination from nc_packet is selected for MAC-header */
1114 		first_dest = nc_packet->neigh_node;
1115 		first_source = nc_packet->nc_path->prev_hop;
1116 		second_dest = neigh_node;
1117 		second_source = ethhdr->h_source;
1118 		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1119 		packet2 = (struct batadv_unicast_packet *)skb->data;
1120 		packet_id1 = nc_packet->packet_id;
1121 		packet_id2 = batadv_skb_crc32(skb,
1122 					      skb->data + sizeof(*packet2));
1123 	} else {
1124 		/* Destination for skb is selected for MAC-header */
1125 		first_dest = neigh_node;
1126 		first_source = ethhdr->h_source;
1127 		second_dest = nc_packet->neigh_node;
1128 		second_source = nc_packet->nc_path->prev_hop;
1129 		packet1 = (struct batadv_unicast_packet *)skb->data;
1130 		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1131 		packet_id1 = batadv_skb_crc32(skb,
1132 					      skb->data + sizeof(*packet1));
1133 		packet_id2 = nc_packet->packet_id;
1134 	}
1135 
1136 	/* Instead of zero padding the smallest data buffer, we
1137 	 * code into the largest.
1138 	 */
1139 	if (skb->len <= nc_packet->skb->len) {
1140 		skb_dest = nc_packet->skb;
1141 		skb_src = skb;
1142 	} else {
1143 		skb_dest = skb;
1144 		skb_src = nc_packet->skb;
1145 	}
1146 
1147 	/* coding_len is used when decoding the packet shorter packet */
1148 	coding_len = skb_src->len - unicast_size;
1149 
1150 	if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1151 		goto out;
1152 
1153 	skb_push(skb_dest, header_add);
1154 
1155 	coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1156 	skb_reset_mac_header(skb_dest);
1157 
1158 	coded_packet->packet_type = BATADV_CODED;
1159 	coded_packet->version = BATADV_COMPAT_VERSION;
1160 	coded_packet->ttl = packet1->ttl;
1161 
1162 	/* Info about first unicast packet */
1163 	ether_addr_copy(coded_packet->first_source, first_source);
1164 	ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1165 	coded_packet->first_crc = packet_id1;
1166 	coded_packet->first_ttvn = packet1->ttvn;
1167 
1168 	/* Info about second unicast packet */
1169 	ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1170 	ether_addr_copy(coded_packet->second_source, second_source);
1171 	ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1172 	coded_packet->second_crc = packet_id2;
1173 	coded_packet->second_ttl = packet2->ttl;
1174 	coded_packet->second_ttvn = packet2->ttvn;
1175 	coded_packet->coded_len = htons(coding_len);
1176 
1177 	/* This is where the magic happens: Code skb_src into skb_dest */
1178 	batadv_nc_memxor(skb_dest->data + coded_size,
1179 			 skb_src->data + unicast_size, coding_len);
1180 
1181 	/* Update counters accordingly */
1182 	if (BATADV_SKB_CB(skb_src)->decoded &&
1183 	    BATADV_SKB_CB(skb_dest)->decoded) {
1184 		/* Both packets are recoded */
1185 		count = skb_src->len + ETH_HLEN;
1186 		count += skb_dest->len + ETH_HLEN;
1187 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1188 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1189 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1190 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1191 		/* Both packets are newly coded */
1192 		count = skb_src->len + ETH_HLEN;
1193 		count += skb_dest->len + ETH_HLEN;
1194 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1195 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1196 	} else if (BATADV_SKB_CB(skb_src)->decoded &&
1197 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1198 		/* skb_src recoded and skb_dest is newly coded */
1199 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1200 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1201 				   skb_src->len + ETH_HLEN);
1202 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1203 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1204 				   skb_dest->len + ETH_HLEN);
1205 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1206 		   BATADV_SKB_CB(skb_dest)->decoded) {
1207 		/* skb_src is newly coded and skb_dest is recoded */
1208 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1209 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1210 				   skb_src->len + ETH_HLEN);
1211 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1212 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1213 				   skb_dest->len + ETH_HLEN);
1214 	}
1215 
1216 	/* skb_src is now coded into skb_dest, so free it */
1217 	consume_skb(skb_src);
1218 
1219 	/* avoid duplicate free of skb from nc_packet */
1220 	nc_packet->skb = NULL;
1221 	batadv_nc_packet_free(nc_packet, false);
1222 
1223 	/* Send the coded packet and return true */
1224 	batadv_send_unicast_skb(skb_dest, first_dest);
1225 	res = true;
1226 out:
1227 	if (router_neigh)
1228 		batadv_neigh_node_put(router_neigh);
1229 	if (router_coding)
1230 		batadv_neigh_node_put(router_coding);
1231 	if (router_neigh_ifinfo)
1232 		batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1233 	if (router_coding_ifinfo)
1234 		batadv_neigh_ifinfo_put(router_coding_ifinfo);
1235 	return res;
1236 }
1237 
1238 /**
1239  * batadv_nc_skb_coding_possible - true if a decoded skb is available at dst.
1240  * @skb: data skb to forward
1241  * @dst: destination mac address of the other skb to code with
1242  * @src: source mac address of skb
1243  *
1244  * Whenever we network code a packet we have to check whether we received it in
1245  * a network coded form. If so, we may not be able to use it for coding because
1246  * some neighbors may also have received (overheard) the packet in the network
1247  * coded form without being able to decode it. It is hard to know which of the
1248  * neighboring nodes was able to decode the packet, therefore we can only
1249  * re-code the packet if the source of the previous encoded packet is involved.
1250  * Since the source encoded the packet we can be certain it has all necessary
1251  * decode information.
1252  *
1253  * Return: true if coding of a decoded packet is allowed.
1254  */
1255 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1256 {
1257 	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1258 		return false;
1259 	return true;
1260 }
1261 
1262 /**
1263  * batadv_nc_path_search - Find the coding path matching in_nc_node and
1264  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1265  * @bat_priv: the bat priv with all the soft interface information
1266  * @in_nc_node: pointer to skb next hop's neighbor nc node
1267  * @out_nc_node: pointer to skb source's neighbor nc node
1268  * @skb: data skb to forward
1269  * @eth_dst: next hop mac address of skb
1270  *
1271  * Return: true if coding of a decoded skb is allowed.
1272  */
1273 static struct batadv_nc_packet *
1274 batadv_nc_path_search(struct batadv_priv *bat_priv,
1275 		      struct batadv_nc_node *in_nc_node,
1276 		      struct batadv_nc_node *out_nc_node,
1277 		      struct sk_buff *skb,
1278 		      u8 *eth_dst)
1279 {
1280 	struct batadv_nc_path *nc_path, nc_path_key;
1281 	struct batadv_nc_packet *nc_packet_out = NULL;
1282 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1283 	struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1284 	int idx;
1285 
1286 	if (!hash)
1287 		return NULL;
1288 
1289 	/* Create almost path key */
1290 	batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1291 			       out_nc_node->addr);
1292 	idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1293 
1294 	/* Check for coding opportunities in this nc_path */
1295 	rcu_read_lock();
1296 	hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1297 		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1298 			continue;
1299 
1300 		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1301 			continue;
1302 
1303 		spin_lock_bh(&nc_path->packet_list_lock);
1304 		if (list_empty(&nc_path->packet_list)) {
1305 			spin_unlock_bh(&nc_path->packet_list_lock);
1306 			continue;
1307 		}
1308 
1309 		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1310 					 &nc_path->packet_list, list) {
1311 			if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1312 							   eth_dst,
1313 							   in_nc_node->addr))
1314 				continue;
1315 
1316 			/* Coding opportunity is found! */
1317 			list_del(&nc_packet->list);
1318 			nc_packet_out = nc_packet;
1319 			break;
1320 		}
1321 
1322 		spin_unlock_bh(&nc_path->packet_list_lock);
1323 		break;
1324 	}
1325 	rcu_read_unlock();
1326 
1327 	return nc_packet_out;
1328 }
1329 
1330 /**
1331  * batadv_nc_skb_src_search - Loops through the list of neighoring nodes of the
1332  *  skb's sender (may be equal to the originator).
1333  * @bat_priv: the bat priv with all the soft interface information
1334  * @skb: data skb to forward
1335  * @eth_dst: next hop mac address of skb
1336  * @eth_src: source mac address of skb
1337  * @in_nc_node: pointer to skb next hop's neighbor nc node
1338  *
1339  * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1340  */
1341 static struct batadv_nc_packet *
1342 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1343 			 struct sk_buff *skb,
1344 			 u8 *eth_dst,
1345 			 u8 *eth_src,
1346 			 struct batadv_nc_node *in_nc_node)
1347 {
1348 	struct batadv_orig_node *orig_node;
1349 	struct batadv_nc_node *out_nc_node;
1350 	struct batadv_nc_packet *nc_packet = NULL;
1351 
1352 	orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1353 	if (!orig_node)
1354 		return NULL;
1355 
1356 	rcu_read_lock();
1357 	list_for_each_entry_rcu(out_nc_node,
1358 				&orig_node->out_coding_list, list) {
1359 		/* Check if the skb is decoded and if recoding is possible */
1360 		if (!batadv_nc_skb_coding_possible(skb,
1361 						   out_nc_node->addr, eth_src))
1362 			continue;
1363 
1364 		/* Search for an opportunity in this nc_path */
1365 		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1366 						  out_nc_node, skb, eth_dst);
1367 		if (nc_packet)
1368 			break;
1369 	}
1370 	rcu_read_unlock();
1371 
1372 	batadv_orig_node_put(orig_node);
1373 	return nc_packet;
1374 }
1375 
1376 /**
1377  * batadv_nc_skb_store_before_coding - set the ethernet src and dst of the
1378  *  unicast skb before it is stored for use in later decoding
1379  * @bat_priv: the bat priv with all the soft interface information
1380  * @skb: data skb to store
1381  * @eth_dst_new: new destination mac address of skb
1382  */
1383 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1384 					      struct sk_buff *skb,
1385 					      u8 *eth_dst_new)
1386 {
1387 	struct ethhdr *ethhdr;
1388 
1389 	/* Copy skb header to change the mac header */
1390 	skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1391 	if (!skb)
1392 		return;
1393 
1394 	/* Set the mac header as if we actually sent the packet uncoded */
1395 	ethhdr = eth_hdr(skb);
1396 	ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1397 	ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1398 
1399 	/* Set data pointer to MAC header to mimic packets from our tx path */
1400 	skb_push(skb, ETH_HLEN);
1401 
1402 	/* Add the packet to the decoding packet pool */
1403 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1404 
1405 	/* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1406 	 * our ref
1407 	 */
1408 	consume_skb(skb);
1409 }
1410 
1411 /**
1412  * batadv_nc_skb_dst_search - Loops through list of neighboring nodes to dst.
1413  * @skb: data skb to forward
1414  * @neigh_node: next hop to forward packet to
1415  * @ethhdr: pointer to the ethernet header inside the skb
1416  *
1417  * Loops through list of neighboring nodes the next hop has a good connection to
1418  * (receives OGMs with a sufficient quality). We need to find a neighbor of our
1419  * next hop that potentially sent a packet which our next hop also received
1420  * (overheard) and has stored for later decoding.
1421  *
1422  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1423  */
1424 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1425 				     struct batadv_neigh_node *neigh_node,
1426 				     struct ethhdr *ethhdr)
1427 {
1428 	struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1429 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1430 	struct batadv_orig_node *orig_node = neigh_node->orig_node;
1431 	struct batadv_nc_node *nc_node;
1432 	struct batadv_nc_packet *nc_packet = NULL;
1433 
1434 	rcu_read_lock();
1435 	list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1436 		/* Search for coding opportunity with this in_nc_node */
1437 		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1438 						     neigh_node->addr,
1439 						     ethhdr->h_source, nc_node);
1440 
1441 		/* Opportunity was found, so stop searching */
1442 		if (nc_packet)
1443 			break;
1444 	}
1445 	rcu_read_unlock();
1446 
1447 	if (!nc_packet)
1448 		return false;
1449 
1450 	/* Save packets for later decoding */
1451 	batadv_nc_skb_store_before_coding(bat_priv, skb,
1452 					  neigh_node->addr);
1453 	batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1454 					  nc_packet->neigh_node->addr);
1455 
1456 	/* Code and send packets */
1457 	if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1458 				   neigh_node))
1459 		return true;
1460 
1461 	/* out of mem ? Coding failed - we have to free the buffered packet
1462 	 * to avoid memleaks. The skb passed as argument will be dealt with
1463 	 * by the calling function.
1464 	 */
1465 	batadv_nc_send_packet(nc_packet);
1466 	return false;
1467 }
1468 
1469 /**
1470  * batadv_nc_skb_add_to_path - buffer skb for later encoding / decoding
1471  * @skb: skb to add to path
1472  * @nc_path: path to add skb to
1473  * @neigh_node: next hop to forward packet to
1474  * @packet_id: checksum to identify packet
1475  *
1476  * Return: true if the packet was buffered or false in case of an error.
1477  */
1478 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1479 				      struct batadv_nc_path *nc_path,
1480 				      struct batadv_neigh_node *neigh_node,
1481 				      __be32 packet_id)
1482 {
1483 	struct batadv_nc_packet *nc_packet;
1484 
1485 	nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1486 	if (!nc_packet)
1487 		return false;
1488 
1489 	/* Initialize nc_packet */
1490 	nc_packet->timestamp = jiffies;
1491 	nc_packet->packet_id = packet_id;
1492 	nc_packet->skb = skb;
1493 	nc_packet->neigh_node = neigh_node;
1494 	nc_packet->nc_path = nc_path;
1495 
1496 	/* Add coding packet to list */
1497 	spin_lock_bh(&nc_path->packet_list_lock);
1498 	list_add_tail(&nc_packet->list, &nc_path->packet_list);
1499 	spin_unlock_bh(&nc_path->packet_list_lock);
1500 
1501 	return true;
1502 }
1503 
1504 /**
1505  * batadv_nc_skb_forward - try to code a packet or add it to the coding packet
1506  *  buffer
1507  * @skb: data skb to forward
1508  * @neigh_node: next hop to forward packet to
1509  *
1510  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1511  */
1512 bool batadv_nc_skb_forward(struct sk_buff *skb,
1513 			   struct batadv_neigh_node *neigh_node)
1514 {
1515 	const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1516 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1517 	struct batadv_unicast_packet *packet;
1518 	struct batadv_nc_path *nc_path;
1519 	struct ethhdr *ethhdr = eth_hdr(skb);
1520 	__be32 packet_id;
1521 	u8 *payload;
1522 
1523 	/* Check if network coding is enabled */
1524 	if (!atomic_read(&bat_priv->network_coding))
1525 		goto out;
1526 
1527 	/* We only handle unicast packets */
1528 	payload = skb_network_header(skb);
1529 	packet = (struct batadv_unicast_packet *)payload;
1530 	if (packet->packet_type != BATADV_UNICAST)
1531 		goto out;
1532 
1533 	/* Try to find a coding opportunity and send the skb if one is found */
1534 	if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1535 		return true;
1536 
1537 	/* Find or create a nc_path for this src-dst pair */
1538 	nc_path = batadv_nc_get_path(bat_priv,
1539 				     bat_priv->nc.coding_hash,
1540 				     ethhdr->h_source,
1541 				     neigh_node->addr);
1542 
1543 	if (!nc_path)
1544 		goto out;
1545 
1546 	/* Add skb to nc_path */
1547 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1548 	if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1549 		goto free_nc_path;
1550 
1551 	/* Packet is consumed */
1552 	return true;
1553 
1554 free_nc_path:
1555 	batadv_nc_path_put(nc_path);
1556 out:
1557 	/* Packet is not consumed */
1558 	return false;
1559 }
1560 
1561 /**
1562  * batadv_nc_skb_store_for_decoding - save a clone of the skb which can be used
1563  *  when decoding coded packets
1564  * @bat_priv: the bat priv with all the soft interface information
1565  * @skb: data skb to store
1566  */
1567 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1568 				      struct sk_buff *skb)
1569 {
1570 	struct batadv_unicast_packet *packet;
1571 	struct batadv_nc_path *nc_path;
1572 	struct ethhdr *ethhdr = eth_hdr(skb);
1573 	__be32 packet_id;
1574 	u8 *payload;
1575 
1576 	/* Check if network coding is enabled */
1577 	if (!atomic_read(&bat_priv->network_coding))
1578 		goto out;
1579 
1580 	/* Check for supported packet type */
1581 	payload = skb_network_header(skb);
1582 	packet = (struct batadv_unicast_packet *)payload;
1583 	if (packet->packet_type != BATADV_UNICAST)
1584 		goto out;
1585 
1586 	/* Find existing nc_path or create a new */
1587 	nc_path = batadv_nc_get_path(bat_priv,
1588 				     bat_priv->nc.decoding_hash,
1589 				     ethhdr->h_source,
1590 				     ethhdr->h_dest);
1591 
1592 	if (!nc_path)
1593 		goto out;
1594 
1595 	/* Clone skb and adjust skb->data to point at batman header */
1596 	skb = skb_clone(skb, GFP_ATOMIC);
1597 	if (unlikely(!skb))
1598 		goto free_nc_path;
1599 
1600 	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1601 		goto free_skb;
1602 
1603 	if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1604 		goto free_skb;
1605 
1606 	/* Add skb to nc_path */
1607 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1608 	if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1609 		goto free_skb;
1610 
1611 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1612 	return;
1613 
1614 free_skb:
1615 	kfree_skb(skb);
1616 free_nc_path:
1617 	batadv_nc_path_put(nc_path);
1618 out:
1619 	return;
1620 }
1621 
1622 /**
1623  * batadv_nc_skb_store_sniffed_unicast - check if a received unicast packet
1624  *  should be saved in the decoding buffer and, if so, store it there
1625  * @bat_priv: the bat priv with all the soft interface information
1626  * @skb: unicast skb to store
1627  */
1628 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1629 					 struct sk_buff *skb)
1630 {
1631 	struct ethhdr *ethhdr = eth_hdr(skb);
1632 
1633 	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1634 		return;
1635 
1636 	/* Set data pointer to MAC header to mimic packets from our tx path */
1637 	skb_push(skb, ETH_HLEN);
1638 
1639 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1640 }
1641 
1642 /**
1643  * batadv_nc_skb_decode_packet - decode given skb using the decode data stored
1644  *  in nc_packet
1645  * @bat_priv: the bat priv with all the soft interface information
1646  * @skb: unicast skb to decode
1647  * @nc_packet: decode data needed to decode the skb
1648  *
1649  * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1650  * in case of an error.
1651  */
1652 static struct batadv_unicast_packet *
1653 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1654 			    struct batadv_nc_packet *nc_packet)
1655 {
1656 	const int h_size = sizeof(struct batadv_unicast_packet);
1657 	const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1658 	struct batadv_unicast_packet *unicast_packet;
1659 	struct batadv_coded_packet coded_packet_tmp;
1660 	struct ethhdr *ethhdr, ethhdr_tmp;
1661 	u8 *orig_dest, ttl, ttvn;
1662 	unsigned int coding_len;
1663 	int err;
1664 
1665 	/* Save headers temporarily */
1666 	memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1667 	memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1668 
1669 	if (skb_cow(skb, 0) < 0)
1670 		return NULL;
1671 
1672 	if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1673 		return NULL;
1674 
1675 	/* Data points to batman header, so set mac header 14 bytes before
1676 	 * and network to data
1677 	 */
1678 	skb_set_mac_header(skb, -ETH_HLEN);
1679 	skb_reset_network_header(skb);
1680 
1681 	/* Reconstruct original mac header */
1682 	ethhdr = eth_hdr(skb);
1683 	*ethhdr = ethhdr_tmp;
1684 
1685 	/* Select the correct unicast header information based on the location
1686 	 * of our mac address in the coded_packet header
1687 	 */
1688 	if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1689 		/* If we are the second destination the packet was overheard,
1690 		 * so the Ethernet address must be copied to h_dest and
1691 		 * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1692 		 */
1693 		ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1694 		skb->pkt_type = PACKET_HOST;
1695 
1696 		orig_dest = coded_packet_tmp.second_orig_dest;
1697 		ttl = coded_packet_tmp.second_ttl;
1698 		ttvn = coded_packet_tmp.second_ttvn;
1699 	} else {
1700 		orig_dest = coded_packet_tmp.first_orig_dest;
1701 		ttl = coded_packet_tmp.ttl;
1702 		ttvn = coded_packet_tmp.first_ttvn;
1703 	}
1704 
1705 	coding_len = ntohs(coded_packet_tmp.coded_len);
1706 
1707 	if (coding_len > skb->len)
1708 		return NULL;
1709 
1710 	/* Here the magic is reversed:
1711 	 *   extract the missing packet from the received coded packet
1712 	 */
1713 	batadv_nc_memxor(skb->data + h_size,
1714 			 nc_packet->skb->data + h_size,
1715 			 coding_len);
1716 
1717 	/* Resize decoded skb if decoded with larger packet */
1718 	if (nc_packet->skb->len > coding_len + h_size) {
1719 		err = pskb_trim_rcsum(skb, coding_len + h_size);
1720 		if (err)
1721 			return NULL;
1722 	}
1723 
1724 	/* Create decoded unicast packet */
1725 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
1726 	unicast_packet->packet_type = BATADV_UNICAST;
1727 	unicast_packet->version = BATADV_COMPAT_VERSION;
1728 	unicast_packet->ttl = ttl;
1729 	ether_addr_copy(unicast_packet->dest, orig_dest);
1730 	unicast_packet->ttvn = ttvn;
1731 
1732 	batadv_nc_packet_free(nc_packet, false);
1733 	return unicast_packet;
1734 }
1735 
1736 /**
1737  * batadv_nc_find_decoding_packet - search through buffered decoding data to
1738  *  find the data needed to decode the coded packet
1739  * @bat_priv: the bat priv with all the soft interface information
1740  * @ethhdr: pointer to the ethernet header inside the coded packet
1741  * @coded: coded packet we try to find decode data for
1742  *
1743  * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1744  */
1745 static struct batadv_nc_packet *
1746 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1747 			       struct ethhdr *ethhdr,
1748 			       struct batadv_coded_packet *coded)
1749 {
1750 	struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1751 	struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1752 	struct batadv_nc_path *nc_path, nc_path_key;
1753 	u8 *dest, *source;
1754 	__be32 packet_id;
1755 	int index;
1756 
1757 	if (!hash)
1758 		return NULL;
1759 
1760 	/* Select the correct packet id based on the location of our mac-addr */
1761 	dest = ethhdr->h_source;
1762 	if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1763 		source = coded->second_source;
1764 		packet_id = coded->second_crc;
1765 	} else {
1766 		source = coded->first_source;
1767 		packet_id = coded->first_crc;
1768 	}
1769 
1770 	batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1771 	index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1772 
1773 	/* Search for matching coding path */
1774 	rcu_read_lock();
1775 	hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1776 		/* Find matching nc_packet */
1777 		spin_lock_bh(&nc_path->packet_list_lock);
1778 		list_for_each_entry(tmp_nc_packet,
1779 				    &nc_path->packet_list, list) {
1780 			if (packet_id == tmp_nc_packet->packet_id) {
1781 				list_del(&tmp_nc_packet->list);
1782 
1783 				nc_packet = tmp_nc_packet;
1784 				break;
1785 			}
1786 		}
1787 		spin_unlock_bh(&nc_path->packet_list_lock);
1788 
1789 		if (nc_packet)
1790 			break;
1791 	}
1792 	rcu_read_unlock();
1793 
1794 	if (!nc_packet)
1795 		batadv_dbg(BATADV_DBG_NC, bat_priv,
1796 			   "No decoding packet found for %u\n", packet_id);
1797 
1798 	return nc_packet;
1799 }
1800 
1801 /**
1802  * batadv_nc_recv_coded_packet - try to decode coded packet and enqueue the
1803  *  resulting unicast packet
1804  * @skb: incoming coded packet
1805  * @recv_if: pointer to interface this packet was received on
1806  *
1807  * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1808  * otherwise.
1809  */
1810 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1811 				       struct batadv_hard_iface *recv_if)
1812 {
1813 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1814 	struct batadv_unicast_packet *unicast_packet;
1815 	struct batadv_coded_packet *coded_packet;
1816 	struct batadv_nc_packet *nc_packet;
1817 	struct ethhdr *ethhdr;
1818 	int hdr_size = sizeof(*coded_packet);
1819 
1820 	/* Check if network coding is enabled */
1821 	if (!atomic_read(&bat_priv->network_coding))
1822 		goto free_skb;
1823 
1824 	/* Make sure we can access (and remove) header */
1825 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
1826 		goto free_skb;
1827 
1828 	coded_packet = (struct batadv_coded_packet *)skb->data;
1829 	ethhdr = eth_hdr(skb);
1830 
1831 	/* Verify frame is destined for us */
1832 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1833 	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1834 		goto free_skb;
1835 
1836 	/* Update stat counter */
1837 	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1838 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1839 
1840 	nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1841 						   coded_packet);
1842 	if (!nc_packet) {
1843 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1844 		goto free_skb;
1845 	}
1846 
1847 	/* Make skb's linear, because decoding accesses the entire buffer */
1848 	if (skb_linearize(skb) < 0)
1849 		goto free_nc_packet;
1850 
1851 	if (skb_linearize(nc_packet->skb) < 0)
1852 		goto free_nc_packet;
1853 
1854 	/* Decode the packet */
1855 	unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1856 	if (!unicast_packet) {
1857 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1858 		goto free_nc_packet;
1859 	}
1860 
1861 	/* Mark packet as decoded to do correct recoding when forwarding */
1862 	BATADV_SKB_CB(skb)->decoded = true;
1863 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1864 	batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1865 			   skb->len + ETH_HLEN);
1866 	return batadv_recv_unicast_packet(skb, recv_if);
1867 
1868 free_nc_packet:
1869 	batadv_nc_packet_free(nc_packet, true);
1870 free_skb:
1871 	kfree_skb(skb);
1872 
1873 	return NET_RX_DROP;
1874 }
1875 
1876 /**
1877  * batadv_nc_mesh_free - clean up network coding memory
1878  * @bat_priv: the bat priv with all the soft interface information
1879  */
1880 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1881 {
1882 	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1883 	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1884 	cancel_delayed_work_sync(&bat_priv->nc.work);
1885 
1886 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1887 	batadv_hash_destroy(bat_priv->nc.coding_hash);
1888 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1889 	batadv_hash_destroy(bat_priv->nc.decoding_hash);
1890 }
1891 
1892 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
1893 /**
1894  * batadv_nc_nodes_seq_print_text - print the nc node information
1895  * @seq: seq file to print on
1896  * @offset: not used
1897  *
1898  * Return: always 0
1899  */
1900 int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
1901 {
1902 	struct net_device *net_dev = (struct net_device *)seq->private;
1903 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
1904 	struct batadv_hashtable *hash = bat_priv->orig_hash;
1905 	struct batadv_hard_iface *primary_if;
1906 	struct hlist_head *head;
1907 	struct batadv_orig_node *orig_node;
1908 	struct batadv_nc_node *nc_node;
1909 	int i;
1910 
1911 	primary_if = batadv_seq_print_text_primary_if_get(seq);
1912 	if (!primary_if)
1913 		goto out;
1914 
1915 	/* Traverse list of originators */
1916 	for (i = 0; i < hash->size; i++) {
1917 		head = &hash->table[i];
1918 
1919 		/* For each orig_node in this bin */
1920 		rcu_read_lock();
1921 		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
1922 			/* no need to print the orig node if it does not have
1923 			 * network coding neighbors
1924 			 */
1925 			if (list_empty(&orig_node->in_coding_list) &&
1926 			    list_empty(&orig_node->out_coding_list))
1927 				continue;
1928 
1929 			seq_printf(seq, "Node:      %pM\n", orig_node->orig);
1930 
1931 			seq_puts(seq, " Ingoing:  ");
1932 			/* For each in_nc_node to this orig_node */
1933 			list_for_each_entry_rcu(nc_node,
1934 						&orig_node->in_coding_list,
1935 						list)
1936 				seq_printf(seq, "%pM ",
1937 					   nc_node->addr);
1938 			seq_puts(seq, "\n Outgoing: ");
1939 			/* For out_nc_node to this orig_node */
1940 			list_for_each_entry_rcu(nc_node,
1941 						&orig_node->out_coding_list,
1942 						list)
1943 				seq_printf(seq, "%pM ",
1944 					   nc_node->addr);
1945 			seq_puts(seq, "\n\n");
1946 		}
1947 		rcu_read_unlock();
1948 	}
1949 
1950 out:
1951 	if (primary_if)
1952 		batadv_hardif_put(primary_if);
1953 	return 0;
1954 }
1955 
1956 /**
1957  * batadv_nc_init_debugfs - create nc folder and related files in debugfs
1958  * @bat_priv: the bat priv with all the soft interface information
1959  *
1960  * Return: 0 on success or negative error number in case of failure
1961  */
1962 int batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
1963 {
1964 	struct dentry *nc_dir, *file;
1965 
1966 	nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
1967 	if (!nc_dir)
1968 		goto out;
1969 
1970 	file = debugfs_create_u8("min_tq", 0644, nc_dir, &bat_priv->nc.min_tq);
1971 	if (!file)
1972 		goto out;
1973 
1974 	file = debugfs_create_u32("max_fwd_delay", 0644, nc_dir,
1975 				  &bat_priv->nc.max_fwd_delay);
1976 	if (!file)
1977 		goto out;
1978 
1979 	file = debugfs_create_u32("max_buffer_time", 0644, nc_dir,
1980 				  &bat_priv->nc.max_buffer_time);
1981 	if (!file)
1982 		goto out;
1983 
1984 	return 0;
1985 
1986 out:
1987 	return -ENOMEM;
1988 }
1989 #endif
1990