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TOMOYO Linux Cross Reference
Linux/net/batman-adv/network-coding.c

Version: ~ [ linux-5.5-rc1 ] ~ [ linux-5.4.2 ] ~ [ linux-5.3.15 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.88 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.158 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.206 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.206 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /* Copyright (C) 2012-2014 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 <linux/debugfs.h>
 19 
 20 #include "main.h"
 21 #include "hash.h"
 22 #include "network-coding.h"
 23 #include "send.h"
 24 #include "originator.h"
 25 #include "hard-interface.h"
 26 #include "routing.h"
 27 
 28 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
 29 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
 30 
 31 static void batadv_nc_worker(struct work_struct *work);
 32 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
 33                                        struct batadv_hard_iface *recv_if);
 34 
 35 /**
 36  * batadv_nc_init - one-time initialization for network coding
 37  */
 38 int __init batadv_nc_init(void)
 39 {
 40         int ret;
 41 
 42         /* Register our packet type */
 43         ret = batadv_recv_handler_register(BATADV_CODED,
 44                                            batadv_nc_recv_coded_packet);
 45 
 46         return ret;
 47 }
 48 
 49 /**
 50  * batadv_nc_start_timer - initialise the nc periodic worker
 51  * @bat_priv: the bat priv with all the soft interface information
 52  */
 53 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
 54 {
 55         queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
 56                            msecs_to_jiffies(10));
 57 }
 58 
 59 /**
 60  * batadv_nc_tvlv_container_update - update the network coding tvlv container
 61  *  after network coding setting change
 62  * @bat_priv: the bat priv with all the soft interface information
 63  */
 64 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
 65 {
 66         char nc_mode;
 67 
 68         nc_mode = atomic_read(&bat_priv->network_coding);
 69 
 70         switch (nc_mode) {
 71         case 0:
 72                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
 73                 break;
 74         case 1:
 75                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
 76                                                NULL, 0);
 77                 break;
 78         }
 79 }
 80 
 81 /**
 82  * batadv_nc_status_update - update the network coding tvlv container after
 83  *  network coding setting change
 84  * @net_dev: the soft interface net device
 85  */
 86 void batadv_nc_status_update(struct net_device *net_dev)
 87 {
 88         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 89 
 90         batadv_nc_tvlv_container_update(bat_priv);
 91 }
 92 
 93 /**
 94  * batadv_nc_tvlv_ogm_handler_v1 - process incoming nc tvlv container
 95  * @bat_priv: the bat priv with all the soft interface information
 96  * @orig: the orig_node of the ogm
 97  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
 98  * @tvlv_value: tvlv buffer containing the gateway data
 99  * @tvlv_value_len: tvlv buffer length
100  */
101 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
102                                           struct batadv_orig_node *orig,
103                                           uint8_t flags,
104                                           void *tvlv_value,
105                                           uint16_t tvlv_value_len)
106 {
107         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
108                 orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_NC;
109         else
110                 orig->capabilities |= BATADV_ORIG_CAPA_HAS_NC;
111 }
112 
113 /**
114  * batadv_nc_mesh_init - initialise coding hash table and start house keeping
115  * @bat_priv: the bat priv with all the soft interface information
116  */
117 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
118 {
119         bat_priv->nc.timestamp_fwd_flush = jiffies;
120         bat_priv->nc.timestamp_sniffed_purge = jiffies;
121 
122         if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
123                 return 0;
124 
125         bat_priv->nc.coding_hash = batadv_hash_new(128);
126         if (!bat_priv->nc.coding_hash)
127                 goto err;
128 
129         batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
130                                    &batadv_nc_coding_hash_lock_class_key);
131 
132         bat_priv->nc.decoding_hash = batadv_hash_new(128);
133         if (!bat_priv->nc.decoding_hash)
134                 goto err;
135 
136         batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
137                                    &batadv_nc_decoding_hash_lock_class_key);
138 
139         INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
140         batadv_nc_start_timer(bat_priv);
141 
142         batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
143                                      NULL, BATADV_TVLV_NC, 1,
144                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
145         batadv_nc_tvlv_container_update(bat_priv);
146         return 0;
147 
148 err:
149         return -ENOMEM;
150 }
151 
152 /**
153  * batadv_nc_init_bat_priv - initialise the nc specific bat_priv variables
154  * @bat_priv: the bat priv with all the soft interface information
155  */
156 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
157 {
158         atomic_set(&bat_priv->network_coding, 1);
159         bat_priv->nc.min_tq = 200;
160         bat_priv->nc.max_fwd_delay = 10;
161         bat_priv->nc.max_buffer_time = 200;
162 }
163 
164 /**
165  * batadv_nc_init_orig - initialise the nc fields of an orig_node
166  * @orig_node: the orig_node which is going to be initialised
167  */
168 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
169 {
170         INIT_LIST_HEAD(&orig_node->in_coding_list);
171         INIT_LIST_HEAD(&orig_node->out_coding_list);
172         spin_lock_init(&orig_node->in_coding_list_lock);
173         spin_lock_init(&orig_node->out_coding_list_lock);
174 }
175 
176 /**
177  * batadv_nc_node_free_rcu - rcu callback to free an nc node and remove
178  *  its refcount on the orig_node
179  * @rcu: rcu pointer of the nc node
180  */
181 static void batadv_nc_node_free_rcu(struct rcu_head *rcu)
182 {
183         struct batadv_nc_node *nc_node;
184 
185         nc_node = container_of(rcu, struct batadv_nc_node, rcu);
186         batadv_orig_node_free_ref(nc_node->orig_node);
187         kfree(nc_node);
188 }
189 
190 /**
191  * batadv_nc_node_free_ref - decrements the nc node refcounter and possibly
192  * frees it
193  * @nc_node: the nc node to free
194  */
195 static void batadv_nc_node_free_ref(struct batadv_nc_node *nc_node)
196 {
197         if (atomic_dec_and_test(&nc_node->refcount))
198                 call_rcu(&nc_node->rcu, batadv_nc_node_free_rcu);
199 }
200 
201 /**
202  * batadv_nc_path_free_ref - decrements the nc path refcounter and possibly
203  * frees it
204  * @nc_path: the nc node to free
205  */
206 static void batadv_nc_path_free_ref(struct batadv_nc_path *nc_path)
207 {
208         if (atomic_dec_and_test(&nc_path->refcount))
209                 kfree_rcu(nc_path, rcu);
210 }
211 
212 /**
213  * batadv_nc_packet_free - frees nc packet
214  * @nc_packet: the nc packet to free
215  */
216 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet)
217 {
218         if (nc_packet->skb)
219                 kfree_skb(nc_packet->skb);
220 
221         batadv_nc_path_free_ref(nc_packet->nc_path);
222         kfree(nc_packet);
223 }
224 
225 /**
226  * batadv_nc_to_purge_nc_node - checks whether an nc node has to be purged
227  * @bat_priv: the bat priv with all the soft interface information
228  * @nc_node: the nc node to check
229  *
230  * Returns true if the entry has to be purged now, false otherwise
231  */
232 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
233                                        struct batadv_nc_node *nc_node)
234 {
235         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
236                 return true;
237 
238         return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
239 }
240 
241 /**
242  * batadv_nc_to_purge_nc_path_coding - checks whether an nc path has timed out
243  * @bat_priv: the bat priv with all the soft interface information
244  * @nc_path: the nc path to check
245  *
246  * Returns true if the entry has to be purged now, false otherwise
247  */
248 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
249                                               struct batadv_nc_path *nc_path)
250 {
251         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
252                 return true;
253 
254         /* purge the path when no packets has been added for 10 times the
255          * max_fwd_delay time
256          */
257         return batadv_has_timed_out(nc_path->last_valid,
258                                     bat_priv->nc.max_fwd_delay * 10);
259 }
260 
261 /**
262  * batadv_nc_to_purge_nc_path_decoding - checks whether an nc path has timed out
263  * @bat_priv: the bat priv with all the soft interface information
264  * @nc_path: the nc path to check
265  *
266  * Returns true if the entry has to be purged now, false otherwise
267  */
268 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
269                                                 struct batadv_nc_path *nc_path)
270 {
271         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
272                 return true;
273 
274         /* purge the path when no packets has been added for 10 times the
275          * max_buffer time
276          */
277         return batadv_has_timed_out(nc_path->last_valid,
278                                     bat_priv->nc.max_buffer_time*10);
279 }
280 
281 /**
282  * batadv_nc_purge_orig_nc_nodes - go through list of nc nodes and purge stale
283  *  entries
284  * @bat_priv: the bat priv with all the soft interface information
285  * @list: list of nc nodes
286  * @lock: nc node list lock
287  * @to_purge: function in charge to decide whether an entry has to be purged or
288  *            not. This function takes the nc node as argument and has to return
289  *            a boolean value: true if the entry has to be deleted, false
290  *            otherwise
291  */
292 static void
293 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
294                               struct list_head *list,
295                               spinlock_t *lock,
296                               bool (*to_purge)(struct batadv_priv *,
297                                                struct batadv_nc_node *))
298 {
299         struct batadv_nc_node *nc_node, *nc_node_tmp;
300 
301         /* For each nc_node in list */
302         spin_lock_bh(lock);
303         list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
304                 /* if an helper function has been passed as parameter,
305                  * ask it if the entry has to be purged or not
306                  */
307                 if (to_purge && !to_purge(bat_priv, nc_node))
308                         continue;
309 
310                 batadv_dbg(BATADV_DBG_NC, bat_priv,
311                            "Removing nc_node %pM -> %pM\n",
312                            nc_node->addr, nc_node->orig_node->orig);
313                 list_del_rcu(&nc_node->list);
314                 batadv_nc_node_free_ref(nc_node);
315         }
316         spin_unlock_bh(lock);
317 }
318 
319 /**
320  * batadv_nc_purge_orig - purges all nc node data attached of the given
321  *  originator
322  * @bat_priv: the bat priv with all the soft interface information
323  * @orig_node: orig_node with the nc node entries to be purged
324  * @to_purge: function in charge to decide whether an entry has to be purged or
325  *            not. This function takes the nc node as argument and has to return
326  *            a boolean value: true is the entry has to be deleted, false
327  *            otherwise
328  */
329 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
330                           struct batadv_orig_node *orig_node,
331                           bool (*to_purge)(struct batadv_priv *,
332                                            struct batadv_nc_node *))
333 {
334         /* Check ingoing nc_node's of this orig_node */
335         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
336                                       &orig_node->in_coding_list_lock,
337                                       to_purge);
338 
339         /* Check outgoing nc_node's of this orig_node */
340         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
341                                       &orig_node->out_coding_list_lock,
342                                       to_purge);
343 }
344 
345 /**
346  * batadv_nc_purge_orig_hash - traverse entire originator hash to check if they
347  *  have timed out nc nodes
348  * @bat_priv: the bat priv with all the soft interface information
349  */
350 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
351 {
352         struct batadv_hashtable *hash = bat_priv->orig_hash;
353         struct hlist_head *head;
354         struct batadv_orig_node *orig_node;
355         uint32_t i;
356 
357         if (!hash)
358                 return;
359 
360         /* For each orig_node */
361         for (i = 0; i < hash->size; i++) {
362                 head = &hash->table[i];
363 
364                 rcu_read_lock();
365                 hlist_for_each_entry_rcu(orig_node, head, hash_entry)
366                         batadv_nc_purge_orig(bat_priv, orig_node,
367                                              batadv_nc_to_purge_nc_node);
368                 rcu_read_unlock();
369         }
370 }
371 
372 /**
373  * batadv_nc_purge_paths - traverse all nc paths part of the hash and remove
374  *  unused ones
375  * @bat_priv: the bat priv with all the soft interface information
376  * @hash: hash table containing the nc paths to check
377  * @to_purge: function in charge to decide whether an entry has to be purged or
378  *            not. This function takes the nc node as argument and has to return
379  *            a boolean value: true is the entry has to be deleted, false
380  *            otherwise
381  */
382 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
383                                   struct batadv_hashtable *hash,
384                                   bool (*to_purge)(struct batadv_priv *,
385                                                    struct batadv_nc_path *))
386 {
387         struct hlist_head *head;
388         struct hlist_node *node_tmp;
389         struct batadv_nc_path *nc_path;
390         spinlock_t *lock; /* Protects lists in hash */
391         uint32_t i;
392 
393         for (i = 0; i < hash->size; i++) {
394                 head = &hash->table[i];
395                 lock = &hash->list_locks[i];
396 
397                 /* For each nc_path in this bin */
398                 spin_lock_bh(lock);
399                 hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
400                         /* if an helper function has been passed as parameter,
401                          * ask it if the entry has to be purged or not
402                          */
403                         if (to_purge && !to_purge(bat_priv, nc_path))
404                                 continue;
405 
406                         /* purging an non-empty nc_path should never happen, but
407                          * is observed under high CPU load. Delay the purging
408                          * until next iteration to allow the packet_list to be
409                          * emptied first.
410                          */
411                         if (!unlikely(list_empty(&nc_path->packet_list))) {
412                                 net_ratelimited_function(printk,
413                                                          KERN_WARNING
414                                                          "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
415                                                          nc_path->prev_hop,
416                                                          nc_path->next_hop);
417                                 continue;
418                         }
419 
420                         /* nc_path is unused, so remove it */
421                         batadv_dbg(BATADV_DBG_NC, bat_priv,
422                                    "Remove nc_path %pM -> %pM\n",
423                                    nc_path->prev_hop, nc_path->next_hop);
424                         hlist_del_rcu(&nc_path->hash_entry);
425                         batadv_nc_path_free_ref(nc_path);
426                 }
427                 spin_unlock_bh(lock);
428         }
429 }
430 
431 /**
432  * batadv_nc_hash_key_gen - computes the nc_path hash key
433  * @key: buffer to hold the final hash key
434  * @src: source ethernet mac address going into the hash key
435  * @dst: destination ethernet mac address going into the hash key
436  */
437 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
438                                    const char *dst)
439 {
440         memcpy(key->prev_hop, src, sizeof(key->prev_hop));
441         memcpy(key->next_hop, dst, sizeof(key->next_hop));
442 }
443 
444 /**
445  * batadv_nc_hash_choose - compute the hash value for an nc path
446  * @data: data to hash
447  * @size: size of the hash table
448  *
449  * Returns the selected index in the hash table for the given data.
450  */
451 static uint32_t batadv_nc_hash_choose(const void *data, uint32_t size)
452 {
453         const struct batadv_nc_path *nc_path = data;
454         uint32_t hash = 0;
455 
456         hash = batadv_hash_bytes(hash, &nc_path->prev_hop,
457                                  sizeof(nc_path->prev_hop));
458         hash = batadv_hash_bytes(hash, &nc_path->next_hop,
459                                  sizeof(nc_path->next_hop));
460 
461         hash += (hash << 3);
462         hash ^= (hash >> 11);
463         hash += (hash << 15);
464 
465         return hash % size;
466 }
467 
468 /**
469  * batadv_nc_hash_compare - comparing function used in the network coding hash
470  *  tables
471  * @node: node in the local table
472  * @data2: second object to compare the node to
473  *
474  * Returns 1 if the two entry are the same, 0 otherwise
475  */
476 static int batadv_nc_hash_compare(const struct hlist_node *node,
477                                   const void *data2)
478 {
479         const struct batadv_nc_path *nc_path1, *nc_path2;
480 
481         nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
482         nc_path2 = data2;
483 
484         /* Return 1 if the two keys are identical */
485         if (memcmp(nc_path1->prev_hop, nc_path2->prev_hop,
486                    sizeof(nc_path1->prev_hop)) != 0)
487                 return 0;
488 
489         if (memcmp(nc_path1->next_hop, nc_path2->next_hop,
490                    sizeof(nc_path1->next_hop)) != 0)
491                 return 0;
492 
493         return 1;
494 }
495 
496 /**
497  * batadv_nc_hash_find - search for an existing nc path and return it
498  * @hash: hash table containing the nc path
499  * @data: search key
500  *
501  * Returns the nc_path if found, NULL otherwise.
502  */
503 static struct batadv_nc_path *
504 batadv_nc_hash_find(struct batadv_hashtable *hash,
505                     void *data)
506 {
507         struct hlist_head *head;
508         struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
509         int index;
510 
511         if (!hash)
512                 return NULL;
513 
514         index = batadv_nc_hash_choose(data, hash->size);
515         head = &hash->table[index];
516 
517         rcu_read_lock();
518         hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
519                 if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
520                         continue;
521 
522                 if (!atomic_inc_not_zero(&nc_path->refcount))
523                         continue;
524 
525                 nc_path_tmp = nc_path;
526                 break;
527         }
528         rcu_read_unlock();
529 
530         return nc_path_tmp;
531 }
532 
533 /**
534  * batadv_nc_send_packet - send non-coded packet and free nc_packet struct
535  * @nc_packet: the nc packet to send
536  */
537 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
538 {
539         batadv_send_skb_packet(nc_packet->skb,
540                                nc_packet->neigh_node->if_incoming,
541                                nc_packet->nc_path->next_hop);
542         nc_packet->skb = NULL;
543         batadv_nc_packet_free(nc_packet);
544 }
545 
546 /**
547  * batadv_nc_sniffed_purge - Checks timestamp of given sniffed nc_packet.
548  * @bat_priv: the bat priv with all the soft interface information
549  * @nc_path: the nc path the packet belongs to
550  * @nc_packet: the nc packet to be checked
551  *
552  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
553  * timeout. If so, the packet is no longer kept and the entry deleted from the
554  * queue. Has to be called with the appropriate locks.
555  *
556  * Returns false as soon as the entry in the fifo queue has not been timed out
557  * yet and true otherwise.
558  */
559 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
560                                     struct batadv_nc_path *nc_path,
561                                     struct batadv_nc_packet *nc_packet)
562 {
563         unsigned long timeout = bat_priv->nc.max_buffer_time;
564         bool res = false;
565 
566         /* Packets are added to tail, so the remaining packets did not time
567          * out and we can stop processing the current queue
568          */
569         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
570             !batadv_has_timed_out(nc_packet->timestamp, timeout))
571                 goto out;
572 
573         /* purge nc packet */
574         list_del(&nc_packet->list);
575         batadv_nc_packet_free(nc_packet);
576 
577         res = true;
578 
579 out:
580         return res;
581 }
582 
583 /**
584  * batadv_nc_fwd_flush - Checks the timestamp of the given nc packet.
585  * @bat_priv: the bat priv with all the soft interface information
586  * @nc_path: the nc path the packet belongs to
587  * @nc_packet: the nc packet to be checked
588  *
589  * Checks whether the given nc packet has hit its forward timeout. If so, the
590  * packet is no longer delayed, immediately sent and the entry deleted from the
591  * queue. Has to be called with the appropriate locks.
592  *
593  * Returns false as soon as the entry in the fifo queue has not been timed out
594  * yet and true otherwise.
595  */
596 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
597                                 struct batadv_nc_path *nc_path,
598                                 struct batadv_nc_packet *nc_packet)
599 {
600         unsigned long timeout = bat_priv->nc.max_fwd_delay;
601 
602         /* Packets are added to tail, so the remaining packets did not time
603          * out and we can stop processing the current queue
604          */
605         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
606             !batadv_has_timed_out(nc_packet->timestamp, timeout))
607                 return false;
608 
609         /* Send packet */
610         batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
611         batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
612                            nc_packet->skb->len + ETH_HLEN);
613         list_del(&nc_packet->list);
614         batadv_nc_send_packet(nc_packet);
615 
616         return true;
617 }
618 
619 /**
620  * batadv_nc_process_nc_paths - traverse given nc packet pool and free timed out
621  *  nc packets
622  * @bat_priv: the bat priv with all the soft interface information
623  * @hash: to be processed hash table
624  * @process_fn: Function called to process given nc packet. Should return true
625  *              to encourage this function to proceed with the next packet.
626  *              Otherwise the rest of the current queue is skipped.
627  */
628 static void
629 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
630                            struct batadv_hashtable *hash,
631                            bool (*process_fn)(struct batadv_priv *,
632                                               struct batadv_nc_path *,
633                                               struct batadv_nc_packet *))
634 {
635         struct hlist_head *head;
636         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
637         struct batadv_nc_path *nc_path;
638         bool ret;
639         int i;
640 
641         if (!hash)
642                 return;
643 
644         /* Loop hash table bins */
645         for (i = 0; i < hash->size; i++) {
646                 head = &hash->table[i];
647 
648                 /* Loop coding paths */
649                 rcu_read_lock();
650                 hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
651                         /* Loop packets */
652                         spin_lock_bh(&nc_path->packet_list_lock);
653                         list_for_each_entry_safe(nc_packet, nc_packet_tmp,
654                                                  &nc_path->packet_list, list) {
655                                 ret = process_fn(bat_priv, nc_path, nc_packet);
656                                 if (!ret)
657                                         break;
658                         }
659                         spin_unlock_bh(&nc_path->packet_list_lock);
660                 }
661                 rcu_read_unlock();
662         }
663 }
664 
665 /**
666  * batadv_nc_worker - periodic task for house keeping related to network coding
667  * @work: kernel work struct
668  */
669 static void batadv_nc_worker(struct work_struct *work)
670 {
671         struct delayed_work *delayed_work;
672         struct batadv_priv_nc *priv_nc;
673         struct batadv_priv *bat_priv;
674         unsigned long timeout;
675 
676         delayed_work = container_of(work, struct delayed_work, work);
677         priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
678         bat_priv = container_of(priv_nc, struct batadv_priv, nc);
679 
680         batadv_nc_purge_orig_hash(bat_priv);
681         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
682                               batadv_nc_to_purge_nc_path_coding);
683         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
684                               batadv_nc_to_purge_nc_path_decoding);
685 
686         timeout = bat_priv->nc.max_fwd_delay;
687 
688         if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
689                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
690                                            batadv_nc_fwd_flush);
691                 bat_priv->nc.timestamp_fwd_flush = jiffies;
692         }
693 
694         if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
695                                  bat_priv->nc.max_buffer_time)) {
696                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
697                                            batadv_nc_sniffed_purge);
698                 bat_priv->nc.timestamp_sniffed_purge = jiffies;
699         }
700 
701         /* Schedule a new check */
702         batadv_nc_start_timer(bat_priv);
703 }
704 
705 /**
706  * batadv_can_nc_with_orig - checks whether the given orig node is suitable for
707  *  coding or not
708  * @bat_priv: the bat priv with all the soft interface information
709  * @orig_node: neighboring orig node which may be used as nc candidate
710  * @ogm_packet: incoming ogm packet also used for the checks
711  *
712  * Returns true if:
713  *  1) The OGM must have the most recent sequence number.
714  *  2) The TTL must be decremented by one and only one.
715  *  3) The OGM must be received from the first hop from orig_node.
716  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
717  */
718 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
719                                     struct batadv_orig_node *orig_node,
720                                     struct batadv_ogm_packet *ogm_packet)
721 {
722         struct batadv_orig_ifinfo *orig_ifinfo;
723         uint32_t last_real_seqno;
724         uint8_t last_ttl;
725 
726         orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
727         if (!orig_ifinfo)
728                 return false;
729 
730         last_ttl = orig_ifinfo->last_ttl;
731         last_real_seqno = orig_ifinfo->last_real_seqno;
732         batadv_orig_ifinfo_free_ref(orig_ifinfo);
733 
734         if (last_real_seqno != ntohl(ogm_packet->seqno))
735                 return false;
736         if (last_ttl != ogm_packet->ttl + 1)
737                 return false;
738         if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
739                 return false;
740         if (ogm_packet->tq < bat_priv->nc.min_tq)
741                 return false;
742 
743         return true;
744 }
745 
746 /**
747  * batadv_nc_find_nc_node - search for an existing nc node and return it
748  * @orig_node: orig node originating the ogm packet
749  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
750  *  (can be equal to orig_node)
751  * @in_coding: traverse incoming or outgoing network coding list
752  *
753  * Returns the nc_node if found, NULL otherwise.
754  */
755 static struct batadv_nc_node
756 *batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
757                         struct batadv_orig_node *orig_neigh_node,
758                         bool in_coding)
759 {
760         struct batadv_nc_node *nc_node, *nc_node_out = NULL;
761         struct list_head *list;
762 
763         if (in_coding)
764                 list = &orig_neigh_node->in_coding_list;
765         else
766                 list = &orig_neigh_node->out_coding_list;
767 
768         /* Traverse list of nc_nodes to orig_node */
769         rcu_read_lock();
770         list_for_each_entry_rcu(nc_node, list, list) {
771                 if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
772                         continue;
773 
774                 if (!atomic_inc_not_zero(&nc_node->refcount))
775                         continue;
776 
777                 /* Found a match */
778                 nc_node_out = nc_node;
779                 break;
780         }
781         rcu_read_unlock();
782 
783         return nc_node_out;
784 }
785 
786 /**
787  * batadv_nc_get_nc_node - retrieves an nc node or creates the entry if it was
788  *  not found
789  * @bat_priv: the bat priv with all the soft interface information
790  * @orig_node: orig node originating the ogm packet
791  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
792  *  (can be equal to orig_node)
793  * @in_coding: traverse incoming or outgoing network coding list
794  *
795  * Returns the nc_node if found or created, NULL in case of an error.
796  */
797 static struct batadv_nc_node
798 *batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
799                        struct batadv_orig_node *orig_node,
800                        struct batadv_orig_node *orig_neigh_node,
801                        bool in_coding)
802 {
803         struct batadv_nc_node *nc_node;
804         spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
805         struct list_head *list;
806 
807         /* Check if nc_node is already added */
808         nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
809 
810         /* Node found */
811         if (nc_node)
812                 return nc_node;
813 
814         nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
815         if (!nc_node)
816                 return NULL;
817 
818         if (!atomic_inc_not_zero(&orig_neigh_node->refcount))
819                 goto free;
820 
821         /* Initialize nc_node */
822         INIT_LIST_HEAD(&nc_node->list);
823         ether_addr_copy(nc_node->addr, orig_node->orig);
824         nc_node->orig_node = orig_neigh_node;
825         atomic_set(&nc_node->refcount, 2);
826 
827         /* Select ingoing or outgoing coding node */
828         if (in_coding) {
829                 lock = &orig_neigh_node->in_coding_list_lock;
830                 list = &orig_neigh_node->in_coding_list;
831         } else {
832                 lock = &orig_neigh_node->out_coding_list_lock;
833                 list = &orig_neigh_node->out_coding_list;
834         }
835 
836         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
837                    nc_node->addr, nc_node->orig_node->orig);
838 
839         /* Add nc_node to orig_node */
840         spin_lock_bh(lock);
841         list_add_tail_rcu(&nc_node->list, list);
842         spin_unlock_bh(lock);
843 
844         return nc_node;
845 
846 free:
847         kfree(nc_node);
848         return NULL;
849 }
850 
851 /**
852  * batadv_nc_update_nc_node - updates stored incoming and outgoing nc node structs
853  *  (best called on incoming OGMs)
854  * @bat_priv: the bat priv with all the soft interface information
855  * @orig_node: orig node originating the ogm packet
856  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
857  *  (can be equal to orig_node)
858  * @ogm_packet: incoming ogm packet
859  * @is_single_hop_neigh: orig_node is a single hop neighbor
860  */
861 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
862                               struct batadv_orig_node *orig_node,
863                               struct batadv_orig_node *orig_neigh_node,
864                               struct batadv_ogm_packet *ogm_packet,
865                               int is_single_hop_neigh)
866 {
867         struct batadv_nc_node *in_nc_node = NULL, *out_nc_node = NULL;
868 
869         /* Check if network coding is enabled */
870         if (!atomic_read(&bat_priv->network_coding))
871                 goto out;
872 
873         /* check if orig node is network coding enabled */
874         if (!(orig_node->capabilities & BATADV_ORIG_CAPA_HAS_NC))
875                 goto out;
876 
877         /* accept ogms from 'good' neighbors and single hop neighbors */
878         if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
879             !is_single_hop_neigh)
880                 goto out;
881 
882         /* Add orig_node as in_nc_node on hop */
883         in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
884                                            orig_neigh_node, true);
885         if (!in_nc_node)
886                 goto out;
887 
888         in_nc_node->last_seen = jiffies;
889 
890         /* Add hop as out_nc_node on orig_node */
891         out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
892                                             orig_node, false);
893         if (!out_nc_node)
894                 goto out;
895 
896         out_nc_node->last_seen = jiffies;
897 
898 out:
899         if (in_nc_node)
900                 batadv_nc_node_free_ref(in_nc_node);
901         if (out_nc_node)
902                 batadv_nc_node_free_ref(out_nc_node);
903 }
904 
905 /**
906  * batadv_nc_get_path - get existing nc_path or allocate a new one
907  * @bat_priv: the bat priv with all the soft interface information
908  * @hash: hash table containing the nc path
909  * @src: ethernet source address - first half of the nc path search key
910  * @dst: ethernet destination address - second half of the nc path search key
911  *
912  * Returns pointer to nc_path if the path was found or created, returns NULL
913  * on error.
914  */
915 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
916                                                  struct batadv_hashtable *hash,
917                                                  uint8_t *src,
918                                                  uint8_t *dst)
919 {
920         int hash_added;
921         struct batadv_nc_path *nc_path, nc_path_key;
922 
923         batadv_nc_hash_key_gen(&nc_path_key, src, dst);
924 
925         /* Search for existing nc_path */
926         nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
927 
928         if (nc_path) {
929                 /* Set timestamp to delay removal of nc_path */
930                 nc_path->last_valid = jiffies;
931                 return nc_path;
932         }
933 
934         /* No existing nc_path was found; create a new */
935         nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
936 
937         if (!nc_path)
938                 return NULL;
939 
940         /* Initialize nc_path */
941         INIT_LIST_HEAD(&nc_path->packet_list);
942         spin_lock_init(&nc_path->packet_list_lock);
943         atomic_set(&nc_path->refcount, 2);
944         nc_path->last_valid = jiffies;
945         ether_addr_copy(nc_path->next_hop, dst);
946         ether_addr_copy(nc_path->prev_hop, src);
947 
948         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
949                    nc_path->prev_hop,
950                    nc_path->next_hop);
951 
952         /* Add nc_path to hash table */
953         hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
954                                      batadv_nc_hash_choose, &nc_path_key,
955                                      &nc_path->hash_entry);
956 
957         if (hash_added < 0) {
958                 kfree(nc_path);
959                 return NULL;
960         }
961 
962         return nc_path;
963 }
964 
965 /**
966  * batadv_nc_random_weight_tq - scale the receivers TQ-value to avoid unfair
967  *  selection of a receiver with slightly lower TQ than the other
968  * @tq: to be weighted tq value
969  */
970 static uint8_t batadv_nc_random_weight_tq(uint8_t tq)
971 {
972         uint8_t rand_val, rand_tq;
973 
974         get_random_bytes(&rand_val, sizeof(rand_val));
975 
976         /* randomize the estimated packet loss (max TQ - estimated TQ) */
977         rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
978 
979         /* normalize the randomized packet loss */
980         rand_tq /= BATADV_TQ_MAX_VALUE;
981 
982         /* convert to (randomized) estimated tq again */
983         return BATADV_TQ_MAX_VALUE - rand_tq;
984 }
985 
986 /**
987  * batadv_nc_memxor - XOR destination with source
988  * @dst: byte array to XOR into
989  * @src: byte array to XOR from
990  * @len: length of destination array
991  */
992 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
993 {
994         unsigned int i;
995 
996         for (i = 0; i < len; ++i)
997                 dst[i] ^= src[i];
998 }
999 
1000 /**
1001  * batadv_nc_code_packets - code a received unicast_packet with an nc packet
1002  *  into a coded_packet and send it
1003  * @bat_priv: the bat priv with all the soft interface information
1004  * @skb: data skb to forward
1005  * @ethhdr: pointer to the ethernet header inside the skb
1006  * @nc_packet: structure containing the packet to the skb can be coded with
1007  * @neigh_node: next hop to forward packet to
1008  *
1009  * Returns true if both packets are consumed, false otherwise.
1010  */
1011 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1012                                    struct sk_buff *skb,
1013                                    struct ethhdr *ethhdr,
1014                                    struct batadv_nc_packet *nc_packet,
1015                                    struct batadv_neigh_node *neigh_node)
1016 {
1017         uint8_t tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1018         struct sk_buff *skb_dest, *skb_src;
1019         struct batadv_unicast_packet *packet1;
1020         struct batadv_unicast_packet *packet2;
1021         struct batadv_coded_packet *coded_packet;
1022         struct batadv_neigh_node *neigh_tmp, *router_neigh;
1023         struct batadv_neigh_node *router_coding = NULL;
1024         struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1025         struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1026         uint8_t *first_source, *first_dest, *second_source, *second_dest;
1027         __be32 packet_id1, packet_id2;
1028         size_t count;
1029         bool res = false;
1030         int coding_len;
1031         int unicast_size = sizeof(*packet1);
1032         int coded_size = sizeof(*coded_packet);
1033         int header_add = coded_size - unicast_size;
1034 
1035         /* TODO: do we need to consider the outgoing interface for
1036          * coded packets?
1037          */
1038         router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1039                                               BATADV_IF_DEFAULT);
1040         if (!router_neigh)
1041                 goto out;
1042 
1043         router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1044                                                       BATADV_IF_DEFAULT);
1045         if (!router_neigh_ifinfo)
1046                 goto out;
1047 
1048         neigh_tmp = nc_packet->neigh_node;
1049         router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1050                                                BATADV_IF_DEFAULT);
1051         if (!router_coding)
1052                 goto out;
1053 
1054         router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1055                                                        BATADV_IF_DEFAULT);
1056         if (!router_coding_ifinfo)
1057                 goto out;
1058 
1059         tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1060         tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1061         tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1062         tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1063 
1064         /* Select one destination for the MAC-header dst-field based on
1065          * weighted TQ-values.
1066          */
1067         if (tq_weighted_neigh >= tq_weighted_coding) {
1068                 /* Destination from nc_packet is selected for MAC-header */
1069                 first_dest = nc_packet->nc_path->next_hop;
1070                 first_source = nc_packet->nc_path->prev_hop;
1071                 second_dest = neigh_node->addr;
1072                 second_source = ethhdr->h_source;
1073                 packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1074                 packet2 = (struct batadv_unicast_packet *)skb->data;
1075                 packet_id1 = nc_packet->packet_id;
1076                 packet_id2 = batadv_skb_crc32(skb,
1077                                               skb->data + sizeof(*packet2));
1078         } else {
1079                 /* Destination for skb is selected for MAC-header */
1080                 first_dest = neigh_node->addr;
1081                 first_source = ethhdr->h_source;
1082                 second_dest = nc_packet->nc_path->next_hop;
1083                 second_source = nc_packet->nc_path->prev_hop;
1084                 packet1 = (struct batadv_unicast_packet *)skb->data;
1085                 packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1086                 packet_id1 = batadv_skb_crc32(skb,
1087                                               skb->data + sizeof(*packet1));
1088                 packet_id2 = nc_packet->packet_id;
1089         }
1090 
1091         /* Instead of zero padding the smallest data buffer, we
1092          * code into the largest.
1093          */
1094         if (skb->len <= nc_packet->skb->len) {
1095                 skb_dest = nc_packet->skb;
1096                 skb_src = skb;
1097         } else {
1098                 skb_dest = skb;
1099                 skb_src = nc_packet->skb;
1100         }
1101 
1102         /* coding_len is used when decoding the packet shorter packet */
1103         coding_len = skb_src->len - unicast_size;
1104 
1105         if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1106                 goto out;
1107 
1108         skb_push(skb_dest, header_add);
1109 
1110         coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1111         skb_reset_mac_header(skb_dest);
1112 
1113         coded_packet->packet_type = BATADV_CODED;
1114         coded_packet->version = BATADV_COMPAT_VERSION;
1115         coded_packet->ttl = packet1->ttl;
1116 
1117         /* Info about first unicast packet */
1118         ether_addr_copy(coded_packet->first_source, first_source);
1119         ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1120         coded_packet->first_crc = packet_id1;
1121         coded_packet->first_ttvn = packet1->ttvn;
1122 
1123         /* Info about second unicast packet */
1124         ether_addr_copy(coded_packet->second_dest, second_dest);
1125         ether_addr_copy(coded_packet->second_source, second_source);
1126         ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1127         coded_packet->second_crc = packet_id2;
1128         coded_packet->second_ttl = packet2->ttl;
1129         coded_packet->second_ttvn = packet2->ttvn;
1130         coded_packet->coded_len = htons(coding_len);
1131 
1132         /* This is where the magic happens: Code skb_src into skb_dest */
1133         batadv_nc_memxor(skb_dest->data + coded_size,
1134                          skb_src->data + unicast_size, coding_len);
1135 
1136         /* Update counters accordingly */
1137         if (BATADV_SKB_CB(skb_src)->decoded &&
1138             BATADV_SKB_CB(skb_dest)->decoded) {
1139                 /* Both packets are recoded */
1140                 count = skb_src->len + ETH_HLEN;
1141                 count += skb_dest->len + ETH_HLEN;
1142                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1143                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1144         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1145                    !BATADV_SKB_CB(skb_dest)->decoded) {
1146                 /* Both packets are newly coded */
1147                 count = skb_src->len + ETH_HLEN;
1148                 count += skb_dest->len + ETH_HLEN;
1149                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1150                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1151         } else if (BATADV_SKB_CB(skb_src)->decoded &&
1152                    !BATADV_SKB_CB(skb_dest)->decoded) {
1153                 /* skb_src recoded and skb_dest is newly coded */
1154                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1155                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1156                                    skb_src->len + ETH_HLEN);
1157                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1158                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1159                                    skb_dest->len + ETH_HLEN);
1160         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1161                    BATADV_SKB_CB(skb_dest)->decoded) {
1162                 /* skb_src is newly coded and skb_dest is recoded */
1163                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1164                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1165                                    skb_src->len + ETH_HLEN);
1166                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1167                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1168                                    skb_dest->len + ETH_HLEN);
1169         }
1170 
1171         /* skb_src is now coded into skb_dest, so free it */
1172         kfree_skb(skb_src);
1173 
1174         /* avoid duplicate free of skb from nc_packet */
1175         nc_packet->skb = NULL;
1176         batadv_nc_packet_free(nc_packet);
1177 
1178         /* Send the coded packet and return true */
1179         batadv_send_skb_packet(skb_dest, neigh_node->if_incoming, first_dest);
1180         res = true;
1181 out:
1182         if (router_neigh)
1183                 batadv_neigh_node_free_ref(router_neigh);
1184         if (router_coding)
1185                 batadv_neigh_node_free_ref(router_coding);
1186         if (router_neigh_ifinfo)
1187                 batadv_neigh_ifinfo_free_ref(router_neigh_ifinfo);
1188         if (router_coding_ifinfo)
1189                 batadv_neigh_ifinfo_free_ref(router_coding_ifinfo);
1190         return res;
1191 }
1192 
1193 /**
1194  * batadv_nc_skb_coding_possible - true if a decoded skb is available at dst.
1195  * @skb: data skb to forward
1196  * @dst: destination mac address of the other skb to code with
1197  * @src: source mac address of skb
1198  *
1199  * Whenever we network code a packet we have to check whether we received it in
1200  * a network coded form. If so, we may not be able to use it for coding because
1201  * some neighbors may also have received (overheard) the packet in the network
1202  * coded form without being able to decode it. It is hard to know which of the
1203  * neighboring nodes was able to decode the packet, therefore we can only
1204  * re-code the packet if the source of the previous encoded packet is involved.
1205  * Since the source encoded the packet we can be certain it has all necessary
1206  * decode information.
1207  *
1208  * Returns true if coding of a decoded packet is allowed.
1209  */
1210 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb,
1211                                           uint8_t *dst, uint8_t *src)
1212 {
1213         if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1214                 return false;
1215         return true;
1216 }
1217 
1218 /**
1219  * batadv_nc_path_search - Find the coding path matching in_nc_node and
1220  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1221  * @bat_priv: the bat priv with all the soft interface information
1222  * @in_nc_node: pointer to skb next hop's neighbor nc node
1223  * @out_nc_node: pointer to skb source's neighbor nc node
1224  * @skb: data skb to forward
1225  * @eth_dst: next hop mac address of skb
1226  *
1227  * Returns true if coding of a decoded skb is allowed.
1228  */
1229 static struct batadv_nc_packet *
1230 batadv_nc_path_search(struct batadv_priv *bat_priv,
1231                       struct batadv_nc_node *in_nc_node,
1232                       struct batadv_nc_node *out_nc_node,
1233                       struct sk_buff *skb,
1234                       uint8_t *eth_dst)
1235 {
1236         struct batadv_nc_path *nc_path, nc_path_key;
1237         struct batadv_nc_packet *nc_packet_out = NULL;
1238         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1239         struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1240         int idx;
1241 
1242         if (!hash)
1243                 return NULL;
1244 
1245         /* Create almost path key */
1246         batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1247                                out_nc_node->addr);
1248         idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1249 
1250         /* Check for coding opportunities in this nc_path */
1251         rcu_read_lock();
1252         hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1253                 if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1254                         continue;
1255 
1256                 if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1257                         continue;
1258 
1259                 spin_lock_bh(&nc_path->packet_list_lock);
1260                 if (list_empty(&nc_path->packet_list)) {
1261                         spin_unlock_bh(&nc_path->packet_list_lock);
1262                         continue;
1263                 }
1264 
1265                 list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1266                                          &nc_path->packet_list, list) {
1267                         if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1268                                                            eth_dst,
1269                                                            in_nc_node->addr))
1270                                 continue;
1271 
1272                         /* Coding opportunity is found! */
1273                         list_del(&nc_packet->list);
1274                         nc_packet_out = nc_packet;
1275                         break;
1276                 }
1277 
1278                 spin_unlock_bh(&nc_path->packet_list_lock);
1279                 break;
1280         }
1281         rcu_read_unlock();
1282 
1283         return nc_packet_out;
1284 }
1285 
1286 /**
1287  * batadv_nc_skb_src_search - Loops through the list of neighoring nodes of the
1288  *  skb's sender (may be equal to the originator).
1289  * @bat_priv: the bat priv with all the soft interface information
1290  * @skb: data skb to forward
1291  * @eth_dst: next hop mac address of skb
1292  * @eth_src: source mac address of skb
1293  * @in_nc_node: pointer to skb next hop's neighbor nc node
1294  *
1295  * Returns an nc packet if a suitable coding packet was found, NULL otherwise.
1296  */
1297 static struct batadv_nc_packet *
1298 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1299                          struct sk_buff *skb,
1300                          uint8_t *eth_dst,
1301                          uint8_t *eth_src,
1302                          struct batadv_nc_node *in_nc_node)
1303 {
1304         struct batadv_orig_node *orig_node;
1305         struct batadv_nc_node *out_nc_node;
1306         struct batadv_nc_packet *nc_packet = NULL;
1307 
1308         orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1309         if (!orig_node)
1310                 return NULL;
1311 
1312         rcu_read_lock();
1313         list_for_each_entry_rcu(out_nc_node,
1314                                 &orig_node->out_coding_list, list) {
1315                 /* Check if the skb is decoded and if recoding is possible */
1316                 if (!batadv_nc_skb_coding_possible(skb,
1317                                                    out_nc_node->addr, eth_src))
1318                         continue;
1319 
1320                 /* Search for an opportunity in this nc_path */
1321                 nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1322                                                   out_nc_node, skb, eth_dst);
1323                 if (nc_packet)
1324                         break;
1325         }
1326         rcu_read_unlock();
1327 
1328         batadv_orig_node_free_ref(orig_node);
1329         return nc_packet;
1330 }
1331 
1332 /**
1333  * batadv_nc_skb_store_before_coding - set the ethernet src and dst of the
1334  *  unicast skb before it is stored for use in later decoding
1335  * @bat_priv: the bat priv with all the soft interface information
1336  * @skb: data skb to store
1337  * @eth_dst_new: new destination mac address of skb
1338  */
1339 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1340                                               struct sk_buff *skb,
1341                                               uint8_t *eth_dst_new)
1342 {
1343         struct ethhdr *ethhdr;
1344 
1345         /* Copy skb header to change the mac header */
1346         skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1347         if (!skb)
1348                 return;
1349 
1350         /* Set the mac header as if we actually sent the packet uncoded */
1351         ethhdr = eth_hdr(skb);
1352         ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1353         ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1354 
1355         /* Set data pointer to MAC header to mimic packets from our tx path */
1356         skb_push(skb, ETH_HLEN);
1357 
1358         /* Add the packet to the decoding packet pool */
1359         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1360 
1361         /* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1362          * our ref
1363          */
1364         kfree_skb(skb);
1365 }
1366 
1367 /**
1368  * batadv_nc_skb_dst_search - Loops through list of neighboring nodes to dst.
1369  * @skb: data skb to forward
1370  * @neigh_node: next hop to forward packet to
1371  * @ethhdr: pointer to the ethernet header inside the skb
1372  *
1373  * Loops through list of neighboring nodes the next hop has a good connection to
1374  * (receives OGMs with a sufficient quality). We need to find a neighbor of our
1375  * next hop that potentially sent a packet which our next hop also received
1376  * (overheard) and has stored for later decoding.
1377  *
1378  * Returns true if the skb was consumed (encoded packet sent) or false otherwise
1379  */
1380 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1381                                      struct batadv_neigh_node *neigh_node,
1382                                      struct ethhdr *ethhdr)
1383 {
1384         struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1385         struct batadv_priv *bat_priv = netdev_priv(netdev);
1386         struct batadv_orig_node *orig_node = neigh_node->orig_node;
1387         struct batadv_nc_node *nc_node;
1388         struct batadv_nc_packet *nc_packet = NULL;
1389 
1390         rcu_read_lock();
1391         list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1392                 /* Search for coding opportunity with this in_nc_node */
1393                 nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1394                                                      neigh_node->addr,
1395                                                      ethhdr->h_source, nc_node);
1396 
1397                 /* Opportunity was found, so stop searching */
1398                 if (nc_packet)
1399                         break;
1400         }
1401         rcu_read_unlock();
1402 
1403         if (!nc_packet)
1404                 return false;
1405 
1406         /* Save packets for later decoding */
1407         batadv_nc_skb_store_before_coding(bat_priv, skb,
1408                                           neigh_node->addr);
1409         batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1410                                           nc_packet->neigh_node->addr);
1411 
1412         /* Code and send packets */
1413         if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1414                                    neigh_node))
1415                 return true;
1416 
1417         /* out of mem ? Coding failed - we have to free the buffered packet
1418          * to avoid memleaks. The skb passed as argument will be dealt with
1419          * by the calling function.
1420          */
1421         batadv_nc_send_packet(nc_packet);
1422         return false;
1423 }
1424 
1425 /**
1426  * batadv_nc_skb_add_to_path - buffer skb for later encoding / decoding
1427  * @skb: skb to add to path
1428  * @nc_path: path to add skb to
1429  * @neigh_node: next hop to forward packet to
1430  * @packet_id: checksum to identify packet
1431  *
1432  * Returns true if the packet was buffered or false in case of an error.
1433  */
1434 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1435                                       struct batadv_nc_path *nc_path,
1436                                       struct batadv_neigh_node *neigh_node,
1437                                       __be32 packet_id)
1438 {
1439         struct batadv_nc_packet *nc_packet;
1440 
1441         nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1442         if (!nc_packet)
1443                 return false;
1444 
1445         /* Initialize nc_packet */
1446         nc_packet->timestamp = jiffies;
1447         nc_packet->packet_id = packet_id;
1448         nc_packet->skb = skb;
1449         nc_packet->neigh_node = neigh_node;
1450         nc_packet->nc_path = nc_path;
1451 
1452         /* Add coding packet to list */
1453         spin_lock_bh(&nc_path->packet_list_lock);
1454         list_add_tail(&nc_packet->list, &nc_path->packet_list);
1455         spin_unlock_bh(&nc_path->packet_list_lock);
1456 
1457         return true;
1458 }
1459 
1460 /**
1461  * batadv_nc_skb_forward - try to code a packet or add it to the coding packet
1462  *  buffer
1463  * @skb: data skb to forward
1464  * @neigh_node: next hop to forward packet to
1465  *
1466  * Returns true if the skb was consumed (encoded packet sent) or false otherwise
1467  */
1468 bool batadv_nc_skb_forward(struct sk_buff *skb,
1469                            struct batadv_neigh_node *neigh_node)
1470 {
1471         const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1472         struct batadv_priv *bat_priv = netdev_priv(netdev);
1473         struct batadv_unicast_packet *packet;
1474         struct batadv_nc_path *nc_path;
1475         struct ethhdr *ethhdr = eth_hdr(skb);
1476         __be32 packet_id;
1477         u8 *payload;
1478 
1479         /* Check if network coding is enabled */
1480         if (!atomic_read(&bat_priv->network_coding))
1481                 goto out;
1482 
1483         /* We only handle unicast packets */
1484         payload = skb_network_header(skb);
1485         packet = (struct batadv_unicast_packet *)payload;
1486         if (packet->packet_type != BATADV_UNICAST)
1487                 goto out;
1488 
1489         /* Try to find a coding opportunity and send the skb if one is found */
1490         if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1491                 return true;
1492 
1493         /* Find or create a nc_path for this src-dst pair */
1494         nc_path = batadv_nc_get_path(bat_priv,
1495                                      bat_priv->nc.coding_hash,
1496                                      ethhdr->h_source,
1497                                      neigh_node->addr);
1498 
1499         if (!nc_path)
1500                 goto out;
1501 
1502         /* Add skb to nc_path */
1503         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1504         if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1505                 goto free_nc_path;
1506 
1507         /* Packet is consumed */
1508         return true;
1509 
1510 free_nc_path:
1511         batadv_nc_path_free_ref(nc_path);
1512 out:
1513         /* Packet is not consumed */
1514         return false;
1515 }
1516 
1517 /**
1518  * batadv_nc_skb_store_for_decoding - save a clone of the skb which can be used
1519  *  when decoding coded packets
1520  * @bat_priv: the bat priv with all the soft interface information
1521  * @skb: data skb to store
1522  */
1523 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1524                                       struct sk_buff *skb)
1525 {
1526         struct batadv_unicast_packet *packet;
1527         struct batadv_nc_path *nc_path;
1528         struct ethhdr *ethhdr = eth_hdr(skb);
1529         __be32 packet_id;
1530         u8 *payload;
1531 
1532         /* Check if network coding is enabled */
1533         if (!atomic_read(&bat_priv->network_coding))
1534                 goto out;
1535 
1536         /* Check for supported packet type */
1537         payload = skb_network_header(skb);
1538         packet = (struct batadv_unicast_packet *)payload;
1539         if (packet->packet_type != BATADV_UNICAST)
1540                 goto out;
1541 
1542         /* Find existing nc_path or create a new */
1543         nc_path = batadv_nc_get_path(bat_priv,
1544                                      bat_priv->nc.decoding_hash,
1545                                      ethhdr->h_source,
1546                                      ethhdr->h_dest);
1547 
1548         if (!nc_path)
1549                 goto out;
1550 
1551         /* Clone skb and adjust skb->data to point at batman header */
1552         skb = skb_clone(skb, GFP_ATOMIC);
1553         if (unlikely(!skb))
1554                 goto free_nc_path;
1555 
1556         if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1557                 goto free_skb;
1558 
1559         if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1560                 goto free_skb;
1561 
1562         /* Add skb to nc_path */
1563         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1564         if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1565                 goto free_skb;
1566 
1567         batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1568         return;
1569 
1570 free_skb:
1571         kfree_skb(skb);
1572 free_nc_path:
1573         batadv_nc_path_free_ref(nc_path);
1574 out:
1575         return;
1576 }
1577 
1578 /**
1579  * batadv_nc_skb_store_sniffed_unicast - check if a received unicast packet
1580  *  should be saved in the decoding buffer and, if so, store it there
1581  * @bat_priv: the bat priv with all the soft interface information
1582  * @skb: unicast skb to store
1583  */
1584 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1585                                          struct sk_buff *skb)
1586 {
1587         struct ethhdr *ethhdr = eth_hdr(skb);
1588 
1589         if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1590                 return;
1591 
1592         /* Set data pointer to MAC header to mimic packets from our tx path */
1593         skb_push(skb, ETH_HLEN);
1594 
1595         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1596 }
1597 
1598 /**
1599  * batadv_nc_skb_decode_packet - decode given skb using the decode data stored
1600  *  in nc_packet
1601  * @bat_priv: the bat priv with all the soft interface information
1602  * @skb: unicast skb to decode
1603  * @nc_packet: decode data needed to decode the skb
1604  *
1605  * Returns pointer to decoded unicast packet if the packet was decoded or NULL
1606  * in case of an error.
1607  */
1608 static struct batadv_unicast_packet *
1609 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1610                             struct batadv_nc_packet *nc_packet)
1611 {
1612         const int h_size = sizeof(struct batadv_unicast_packet);
1613         const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1614         struct batadv_unicast_packet *unicast_packet;
1615         struct batadv_coded_packet coded_packet_tmp;
1616         struct ethhdr *ethhdr, ethhdr_tmp;
1617         uint8_t *orig_dest, ttl, ttvn;
1618         unsigned int coding_len;
1619         int err;
1620 
1621         /* Save headers temporarily */
1622         memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1623         memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1624 
1625         if (skb_cow(skb, 0) < 0)
1626                 return NULL;
1627 
1628         if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1629                 return NULL;
1630 
1631         /* Data points to batman header, so set mac header 14 bytes before
1632          * and network to data
1633          */
1634         skb_set_mac_header(skb, -ETH_HLEN);
1635         skb_reset_network_header(skb);
1636 
1637         /* Reconstruct original mac header */
1638         ethhdr = eth_hdr(skb);
1639         *ethhdr = ethhdr_tmp;
1640 
1641         /* Select the correct unicast header information based on the location
1642          * of our mac address in the coded_packet header
1643          */
1644         if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1645                 /* If we are the second destination the packet was overheard,
1646                  * so the Ethernet address must be copied to h_dest and
1647                  * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1648                  */
1649                 ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1650                 skb->pkt_type = PACKET_HOST;
1651 
1652                 orig_dest = coded_packet_tmp.second_orig_dest;
1653                 ttl = coded_packet_tmp.second_ttl;
1654                 ttvn = coded_packet_tmp.second_ttvn;
1655         } else {
1656                 orig_dest = coded_packet_tmp.first_orig_dest;
1657                 ttl = coded_packet_tmp.ttl;
1658                 ttvn = coded_packet_tmp.first_ttvn;
1659         }
1660 
1661         coding_len = ntohs(coded_packet_tmp.coded_len);
1662 
1663         if (coding_len > skb->len)
1664                 return NULL;
1665 
1666         /* Here the magic is reversed:
1667          *   extract the missing packet from the received coded packet
1668          */
1669         batadv_nc_memxor(skb->data + h_size,
1670                          nc_packet->skb->data + h_size,
1671                          coding_len);
1672 
1673         /* Resize decoded skb if decoded with larger packet */
1674         if (nc_packet->skb->len > coding_len + h_size) {
1675                 err = pskb_trim_rcsum(skb, coding_len + h_size);
1676                 if (err)
1677                         return NULL;
1678         }
1679 
1680         /* Create decoded unicast packet */
1681         unicast_packet = (struct batadv_unicast_packet *)skb->data;
1682         unicast_packet->packet_type = BATADV_UNICAST;
1683         unicast_packet->version = BATADV_COMPAT_VERSION;
1684         unicast_packet->ttl = ttl;
1685         ether_addr_copy(unicast_packet->dest, orig_dest);
1686         unicast_packet->ttvn = ttvn;
1687 
1688         batadv_nc_packet_free(nc_packet);
1689         return unicast_packet;
1690 }
1691 
1692 /**
1693  * batadv_nc_find_decoding_packet - search through buffered decoding data to
1694  *  find the data needed to decode the coded packet
1695  * @bat_priv: the bat priv with all the soft interface information
1696  * @ethhdr: pointer to the ethernet header inside the coded packet
1697  * @coded: coded packet we try to find decode data for
1698  *
1699  * Returns pointer to nc packet if the needed data was found or NULL otherwise.
1700  */
1701 static struct batadv_nc_packet *
1702 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1703                                struct ethhdr *ethhdr,
1704                                struct batadv_coded_packet *coded)
1705 {
1706         struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1707         struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1708         struct batadv_nc_path *nc_path, nc_path_key;
1709         uint8_t *dest, *source;
1710         __be32 packet_id;
1711         int index;
1712 
1713         if (!hash)
1714                 return NULL;
1715 
1716         /* Select the correct packet id based on the location of our mac-addr */
1717         dest = ethhdr->h_source;
1718         if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1719                 source = coded->second_source;
1720                 packet_id = coded->second_crc;
1721         } else {
1722                 source = coded->first_source;
1723                 packet_id = coded->first_crc;
1724         }
1725 
1726         batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1727         index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1728 
1729         /* Search for matching coding path */
1730         rcu_read_lock();
1731         hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1732                 /* Find matching nc_packet */
1733                 spin_lock_bh(&nc_path->packet_list_lock);
1734                 list_for_each_entry(tmp_nc_packet,
1735                                     &nc_path->packet_list, list) {
1736                         if (packet_id == tmp_nc_packet->packet_id) {
1737                                 list_del(&tmp_nc_packet->list);
1738 
1739                                 nc_packet = tmp_nc_packet;
1740                                 break;
1741                         }
1742                 }
1743                 spin_unlock_bh(&nc_path->packet_list_lock);
1744 
1745                 if (nc_packet)
1746                         break;
1747         }
1748         rcu_read_unlock();
1749 
1750         if (!nc_packet)
1751                 batadv_dbg(BATADV_DBG_NC, bat_priv,
1752                            "No decoding packet found for %u\n", packet_id);
1753 
1754         return nc_packet;
1755 }
1756 
1757 /**
1758  * batadv_nc_recv_coded_packet - try to decode coded packet and enqueue the
1759  *  resulting unicast packet
1760  * @skb: incoming coded packet
1761  * @recv_if: pointer to interface this packet was received on
1762  */
1763 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1764                                        struct batadv_hard_iface *recv_if)
1765 {
1766         struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1767         struct batadv_unicast_packet *unicast_packet;
1768         struct batadv_coded_packet *coded_packet;
1769         struct batadv_nc_packet *nc_packet;
1770         struct ethhdr *ethhdr;
1771         int hdr_size = sizeof(*coded_packet);
1772 
1773         /* Check if network coding is enabled */
1774         if (!atomic_read(&bat_priv->network_coding))
1775                 return NET_RX_DROP;
1776 
1777         /* Make sure we can access (and remove) header */
1778         if (unlikely(!pskb_may_pull(skb, hdr_size)))
1779                 return NET_RX_DROP;
1780 
1781         coded_packet = (struct batadv_coded_packet *)skb->data;
1782         ethhdr = eth_hdr(skb);
1783 
1784         /* Verify frame is destined for us */
1785         if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1786             !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1787                 return NET_RX_DROP;
1788 
1789         /* Update stat counter */
1790         if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1791                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1792 
1793         nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1794                                                    coded_packet);
1795         if (!nc_packet) {
1796                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1797                 return NET_RX_DROP;
1798         }
1799 
1800         /* Make skb's linear, because decoding accesses the entire buffer */
1801         if (skb_linearize(skb) < 0)
1802                 goto free_nc_packet;
1803 
1804         if (skb_linearize(nc_packet->skb) < 0)
1805                 goto free_nc_packet;
1806 
1807         /* Decode the packet */
1808         unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1809         if (!unicast_packet) {
1810                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1811                 goto free_nc_packet;
1812         }
1813 
1814         /* Mark packet as decoded to do correct recoding when forwarding */
1815         BATADV_SKB_CB(skb)->decoded = true;
1816         batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1817         batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1818                            skb->len + ETH_HLEN);
1819         return batadv_recv_unicast_packet(skb, recv_if);
1820 
1821 free_nc_packet:
1822         batadv_nc_packet_free(nc_packet);
1823         return NET_RX_DROP;
1824 }
1825 
1826 /**
1827  * batadv_nc_mesh_free - clean up network coding memory
1828  * @bat_priv: the bat priv with all the soft interface information
1829  */
1830 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1831 {
1832         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1833         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1834         cancel_delayed_work_sync(&bat_priv->nc.work);
1835 
1836         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1837         batadv_hash_destroy(bat_priv->nc.coding_hash);
1838         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1839         batadv_hash_destroy(bat_priv->nc.decoding_hash);
1840 }
1841 
1842 /**
1843  * batadv_nc_nodes_seq_print_text - print the nc node information
1844  * @seq: seq file to print on
1845  * @offset: not used
1846  */
1847 int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
1848 {
1849         struct net_device *net_dev = (struct net_device *)seq->private;
1850         struct batadv_priv *bat_priv = netdev_priv(net_dev);
1851         struct batadv_hashtable *hash = bat_priv->orig_hash;
1852         struct batadv_hard_iface *primary_if;
1853         struct hlist_head *head;
1854         struct batadv_orig_node *orig_node;
1855         struct batadv_nc_node *nc_node;
1856         int i;
1857 
1858         primary_if = batadv_seq_print_text_primary_if_get(seq);
1859         if (!primary_if)
1860                 goto out;
1861 
1862         /* Traverse list of originators */
1863         for (i = 0; i < hash->size; i++) {
1864                 head = &hash->table[i];
1865 
1866                 /* For each orig_node in this bin */
1867                 rcu_read_lock();
1868                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
1869                         /* no need to print the orig node if it does not have
1870                          * network coding neighbors
1871                          */
1872                         if (list_empty(&orig_node->in_coding_list) &&
1873                             list_empty(&orig_node->out_coding_list))
1874                                 continue;
1875 
1876                         seq_printf(seq, "Node:      %pM\n", orig_node->orig);
1877 
1878                         seq_puts(seq, " Ingoing:  ");
1879                         /* For each in_nc_node to this orig_node */
1880                         list_for_each_entry_rcu(nc_node,
1881                                                 &orig_node->in_coding_list,
1882                                                 list)
1883                                 seq_printf(seq, "%pM ",
1884                                            nc_node->addr);
1885                         seq_puts(seq, "\n");
1886 
1887                         seq_puts(seq, " Outgoing: ");
1888                         /* For out_nc_node to this orig_node */
1889                         list_for_each_entry_rcu(nc_node,
1890                                                 &orig_node->out_coding_list,
1891                                                 list)
1892                                 seq_printf(seq, "%pM ",
1893                                            nc_node->addr);
1894                         seq_puts(seq, "\n\n");
1895                 }
1896                 rcu_read_unlock();
1897         }
1898 
1899 out:
1900         if (primary_if)
1901                 batadv_hardif_free_ref(primary_if);
1902         return 0;
1903 }
1904 
1905 /**
1906  * batadv_nc_init_debugfs - create nc folder and related files in debugfs
1907  * @bat_priv: the bat priv with all the soft interface information
1908  */
1909 int batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
1910 {
1911         struct dentry *nc_dir, *file;
1912 
1913         nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
1914         if (!nc_dir)
1915                 goto out;
1916 
1917         file = debugfs_create_u8("min_tq", S_IRUGO | S_IWUSR, nc_dir,
1918                                  &bat_priv->nc.min_tq);
1919         if (!file)
1920                 goto out;
1921 
1922         file = debugfs_create_u32("max_fwd_delay", S_IRUGO | S_IWUSR, nc_dir,
1923                                   &bat_priv->nc.max_fwd_delay);
1924         if (!file)
1925                 goto out;
1926 
1927         file = debugfs_create_u32("max_buffer_time", S_IRUGO | S_IWUSR, nc_dir,
1928                                   &bat_priv->nc.max_buffer_time);
1929         if (!file)
1930                 goto out;
1931 
1932         return 0;
1933 
1934 out:
1935         return -ENOMEM;
1936 }
1937 

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