net/batman-adv/network-coding.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2012-2019  B.A.T.M.A.N. contributors:
   3  *
   4  * Martin Hundebøll, Jeppe Ledet-Pedersen
   5  */
   6
   7 #include "network-coding.h"
   8 #include "main.h"
   9
  10 #include <linux/atomic.h>
  11 #include <linux/bitops.h>
  12 #include <linux/byteorder/generic.h>
  13 #include <linux/compiler.h>
  14 #include <linux/debugfs.h>
  15 #include <linux/errno.h>
  16 #include <linux/etherdevice.h>
  17 #include <linux/gfp.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/if_packet.h>
  20 #include <linux/init.h>
  21 #include <linux/jhash.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/kernel.h>
  24 #include <linux/kref.h>
  25 #include <linux/list.h>
  26 #include <linux/lockdep.h>
  27 #include <linux/net.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/printk.h>
  30 #include <linux/random.h>
  31 #include <linux/rculist.h>
  32 #include <linux/rcupdate.h>
  33 #include <linux/seq_file.h>
  34 #include <linux/skbuff.h>
  35 #include <linux/slab.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/stddef.h>
  38 #include <linux/string.h>
  39 #include <linux/workqueue.h>
  40 #include <uapi/linux/batadv_packet.h>
  41
  42 #include "hard-interface.h"
  43 #include "hash.h"
  44 #include "log.h"
  45 #include "originator.h"
  46 #include "routing.h"
  47 #include "send.h"
  48 #include "tvlv.h"
  49
  50 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
  51 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
  52
  53 static void batadv_nc_worker(struct work_struct *work);
  54 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
  55                                        struct batadv_hard_iface *recv_if);
  56
  57 /**
  58  * batadv_nc_init() - one-time initialization for network coding
  59  *
  60  * Return: 0 on success or negative error number in case of failure
  61  */
  62 int __init batadv_nc_init(void)
  63 {
  64         int ret;
  65
  66         /* Register our packet type */
  67         ret = batadv_recv_handler_register(BATADV_CODED,
  68                                            batadv_nc_recv_coded_packet);
  69
  70         return ret;
  71 }
  72
  73 /**
  74  * batadv_nc_start_timer() - initialise the nc periodic worker
  75  * @bat_priv: the bat priv with all the soft interface information
  76  */
  77 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
  78 {
  79         queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
  80                            msecs_to_jiffies(10));
  81 }
  82
  83 /**
  84  * batadv_nc_tvlv_container_update() - update the network coding tvlv container
  85  *  after network coding setting change
  86  * @bat_priv: the bat priv with all the soft interface information
  87  */
  88 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
  89 {
  90         char nc_mode;
  91
  92         nc_mode = atomic_read(&bat_priv->network_coding);
  93
  94         switch (nc_mode) {
  95         case 0:
  96                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
  97                 break;
  98         case 1:
  99                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
 100                                                NULL, 0);
 101                 break;
 102         }
 103 }
 104
 105 /**
 106  * batadv_nc_status_update() - update the network coding tvlv container after
 107  *  network coding setting change
 108  * @net_dev: the soft interface net device
 109  */
 110 void batadv_nc_status_update(struct net_device *net_dev)
 111 {
 112         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 113
 114         batadv_nc_tvlv_container_update(bat_priv);
 115 }
 116
 117 /**
 118  * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
 119  * @bat_priv: the bat priv with all the soft interface information
 120  * @orig: the orig_node of the ogm
 121  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
 122  * @tvlv_value: tvlv buffer containing the gateway data
 123  * @tvlv_value_len: tvlv buffer length
 124  */
 125 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
 126                                           struct batadv_orig_node *orig,
 127                                           u8 flags,
 128                                           void *tvlv_value, u16 tvlv_value_len)
 129 {
 130         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
 131                 clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 132         else
 133                 set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 134 }
 135
 136 /**
 137  * batadv_nc_mesh_init() - initialise coding hash table and start house keeping
 138  * @bat_priv: the bat priv with all the soft interface information
 139  *
 140  * Return: 0 on success or negative error number in case of failure
 141  */
 142 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
 143 {
 144         bat_priv->nc.timestamp_fwd_flush = jiffies;
 145         bat_priv->nc.timestamp_sniffed_purge = jiffies;
 146
 147         if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
 148                 return 0;
 149
 150         bat_priv->nc.coding_hash = batadv_hash_new(128);
 151         if (!bat_priv->nc.coding_hash)
 152                 goto err;
 153
 154         batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
 155                                    &batadv_nc_coding_hash_lock_class_key);
 156
 157         bat_priv->nc.decoding_hash = batadv_hash_new(128);
 158         if (!bat_priv->nc.decoding_hash)
 159                 goto err;
 160
 161         batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
 162                                    &batadv_nc_decoding_hash_lock_class_key);
 163
 164         INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
 165         batadv_nc_start_timer(bat_priv);
 166
 167         batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
 168                                      NULL, BATADV_TVLV_NC, 1,
 169                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 170         batadv_nc_tvlv_container_update(bat_priv);
 171         return 0;
 172
 173 err:
 174         return -ENOMEM;
 175 }
 176
 177 /**
 178  * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
 179  * @bat_priv: the bat priv with all the soft interface information
 180  */
 181 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
 182 {
 183         atomic_set(&bat_priv->network_coding, 0);
 184         bat_priv->nc.min_tq = 200;
 185         bat_priv->nc.max_fwd_delay = 10;
 186         bat_priv->nc.max_buffer_time = 200;
 187 }
 188
 189 /**
 190  * batadv_nc_init_orig() - initialise the nc fields of an orig_node
 191  * @orig_node: the orig_node which is going to be initialised
 192  */
 193 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
 194 {
 195         INIT_LIST_HEAD(&orig_node->in_coding_list);
 196         INIT_LIST_HEAD(&orig_node->out_coding_list);
 197         spin_lock_init(&orig_node->in_coding_list_lock);
 198         spin_lock_init(&orig_node->out_coding_list_lock);
 199 }
 200
 201 /**
 202  * batadv_nc_node_release() - release nc_node from lists and queue for free
 203  *  after rcu grace period
 204  * @ref: kref pointer of the nc_node
 205  */
 206 static void batadv_nc_node_release(struct kref *ref)
 207 {
 208         struct batadv_nc_node *nc_node;
 209
 210         nc_node = container_of(ref, struct batadv_nc_node, refcount);
 211
 212         batadv_orig_node_put(nc_node->orig_node);
 213         kfree_rcu(nc_node, rcu);
 214 }
 215
 216 /**
 217  * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
 218  *  release it
 219  * @nc_node: nc_node to be free'd
 220  */
 221 static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
 222 {
 223         kref_put(&nc_node->refcount, batadv_nc_node_release);
 224 }
 225
 226 /**
 227  * batadv_nc_path_release() - release nc_path from lists and queue for free
 228  *  after rcu grace period
 229  * @ref: kref pointer of the nc_path
 230  */
 231 static void batadv_nc_path_release(struct kref *ref)
 232 {
 233         struct batadv_nc_path *nc_path;
 234
 235         nc_path = container_of(ref, struct batadv_nc_path, refcount);
 236
 237         kfree_rcu(nc_path, rcu);
 238 }
 239
 240 /**
 241  * batadv_nc_path_put() - decrement the nc_path refcounter and possibly
 242  *  release it
 243  * @nc_path: nc_path to be free'd
 244  */
 245 static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
 246 {
 247         kref_put(&nc_path->refcount, batadv_nc_path_release);
 248 }
 249
 250 /**
 251  * batadv_nc_packet_free() - frees nc packet
 252  * @nc_packet: the nc packet to free
 253  * @dropped: whether the packet is freed because is is dropped
 254  */
 255 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
 256                                   bool dropped)
 257 {
 258         if (dropped)
 259                 kfree_skb(nc_packet->skb);
 260         else
 261                 consume_skb(nc_packet->skb);
 262
 263         batadv_nc_path_put(nc_packet->nc_path);
 264         kfree(nc_packet);
 265 }
 266
 267 /**
 268  * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
 269  * @bat_priv: the bat priv with all the soft interface information
 270  * @nc_node: the nc node to check
 271  *
 272  * Return: true if the entry has to be purged now, false otherwise
 273  */
 274 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
 275                                        struct batadv_nc_node *nc_node)
 276 {
 277         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 278                 return true;
 279
 280         return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
 281 }
 282
 283 /**
 284  * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
 285  * @bat_priv: the bat priv with all the soft interface information
 286  * @nc_path: the nc path to check
 287  *
 288  * Return: true if the entry has to be purged now, false otherwise
 289  */
 290 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
 291                                               struct batadv_nc_path *nc_path)
 292 {
 293         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 294                 return true;
 295
 296         /* purge the path when no packets has been added for 10 times the
 297          * max_fwd_delay time
 298          */
 299         return batadv_has_timed_out(nc_path->last_valid,
 300                                     bat_priv->nc.max_fwd_delay * 10);
 301 }
 302
 303 /**
 304  * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
 305  *  out
 306  * @bat_priv: the bat priv with all the soft interface information
 307  * @nc_path: the nc path to check
 308  *
 309  * Return: true if the entry has to be purged now, false otherwise
 310  */
 311 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
 312                                                 struct batadv_nc_path *nc_path)
 313 {
 314         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 315                 return true;
 316
 317         /* purge the path when no packets has been added for 10 times the
 318          * max_buffer time
 319          */
 320         return batadv_has_timed_out(nc_path->last_valid,
 321                                     bat_priv->nc.max_buffer_time * 10);
 322 }
 323
 324 /**
 325  * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
 326  *  entries
 327  * @bat_priv: the bat priv with all the soft interface information
 328  * @list: list of nc nodes
 329  * @lock: nc node list lock
 330  * @to_purge: function in charge to decide whether an entry has to be purged or
 331  *            not. This function takes the nc node as argument and has to return
 332  *            a boolean value: true if the entry has to be deleted, false
 333  *            otherwise
 334  */
 335 static void
 336 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
 337                               struct list_head *list,
 338                               spinlock_t *lock,
 339                               bool (*to_purge)(struct batadv_priv *,
 340                                                struct batadv_nc_node *))
 341 {
 342         struct batadv_nc_node *nc_node, *nc_node_tmp;
 343
 344         /* For each nc_node in list */
 345         spin_lock_bh(lock);
 346         list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
 347                 /* if an helper function has been passed as parameter,
 348                  * ask it if the entry has to be purged or not
 349                  */
 350                 if (to_purge && !to_purge(bat_priv, nc_node))
 351                         continue;
 352
 353                 batadv_dbg(BATADV_DBG_NC, bat_priv,
 354                            "Removing nc_node %pM -> %pM\n",
 355                            nc_node->addr, nc_node->orig_node->orig);
 356                 list_del_rcu(&nc_node->list);
 357                 batadv_nc_node_put(nc_node);
 358         }
 359         spin_unlock_bh(lock);
 360 }
 361
 362 /**
 363  * batadv_nc_purge_orig() - purges all nc node data attached of the given
 364  *  originator
 365  * @bat_priv: the bat priv with all the soft interface information
 366  * @orig_node: orig_node with the nc node entries to be purged
 367  * @to_purge: function in charge to decide whether an entry has to be purged or
 368  *            not. This function takes the nc node as argument and has to return
 369  *            a boolean value: true is the entry has to be deleted, false
 370  *            otherwise
 371  */
 372 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
 373                           struct batadv_orig_node *orig_node,
 374                           bool (*to_purge)(struct batadv_priv *,
 375                                            struct batadv_nc_node *))
 376 {
 377         /* Check ingoing nc_node's of this orig_node */
 378         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
 379                                       &orig_node->in_coding_list_lock,
 380                                       to_purge);
 381
 382         /* Check outgoing nc_node's of this orig_node */
 383         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
 384                                       &orig_node->out_coding_list_lock,
 385                                       to_purge);
 386 }
 387
 388 /**
 389  * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
 390  *  they have timed out nc nodes
 391  * @bat_priv: the bat priv with all the soft interface information
 392  */
 393 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
 394 {
 395         struct batadv_hashtable *hash = bat_priv->orig_hash;
 396         struct hlist_head *head;
 397         struct batadv_orig_node *orig_node;
 398         u32 i;
 399
 400         if (!hash)
 401                 return;
 402
 403         /* For each orig_node */
 404         for (i = 0; i < hash->size; i++) {
 405                 head = &hash->table[i];
 406
 407                 rcu_read_lock();
 408                 hlist_for_each_entry_rcu(orig_node, head, hash_entry)
 409                         batadv_nc_purge_orig(bat_priv, orig_node,
 410                                              batadv_nc_to_purge_nc_node);
 411                 rcu_read_unlock();
 412         }
 413 }
 414
 415 /**
 416  * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
 417  *  unused ones
 418  * @bat_priv: the bat priv with all the soft interface information
 419  * @hash: hash table containing the nc paths to check
 420  * @to_purge: function in charge to decide whether an entry has to be purged or
 421  *            not. This function takes the nc node as argument and has to return
 422  *            a boolean value: true is the entry has to be deleted, false
 423  *            otherwise
 424  */
 425 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
 426                                   struct batadv_hashtable *hash,
 427                                   bool (*to_purge)(struct batadv_priv *,
 428                                                    struct batadv_nc_path *))
 429 {
 430         struct hlist_head *head;
 431         struct hlist_node *node_tmp;
 432         struct batadv_nc_path *nc_path;
 433         spinlock_t *lock; /* Protects lists in hash */
 434         u32 i;
 435
 436         for (i = 0; i < hash->size; i++) {
 437                 head = &hash->table[i];
 438                 lock = &hash->list_locks[i];
 439
 440                 /* For each nc_path in this bin */
 441                 spin_lock_bh(lock);
 442                 hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
 443                         /* if an helper function has been passed as parameter,
 444                          * ask it if the entry has to be purged or not
 445                          */
 446                         if (to_purge && !to_purge(bat_priv, nc_path))
 447                                 continue;
 448
 449                         /* purging an non-empty nc_path should never happen, but
 450                          * is observed under high CPU load. Delay the purging
 451                          * until next iteration to allow the packet_list to be
 452                          * emptied first.
 453                          */
 454                         if (!unlikely(list_empty(&nc_path->packet_list))) {
 455                                 net_ratelimited_function(printk,
 456                                                          KERN_WARNING
 457                                                          "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
 458                                                          nc_path->prev_hop,
 459                                                          nc_path->next_hop);
 460                                 continue;
 461                         }
 462
 463                         /* nc_path is unused, so remove it */
 464                         batadv_dbg(BATADV_DBG_NC, bat_priv,
 465                                    "Remove nc_path %pM -> %pM\n",
 466                                    nc_path->prev_hop, nc_path->next_hop);
 467                         hlist_del_rcu(&nc_path->hash_entry);
 468                         batadv_nc_path_put(nc_path);
 469                 }
 470                 spin_unlock_bh(lock);
 471         }
 472 }
 473
 474 /**
 475  * batadv_nc_hash_key_gen() - computes the nc_path hash key
 476  * @key: buffer to hold the final hash key
 477  * @src: source ethernet mac address going into the hash key
 478  * @dst: destination ethernet mac address going into the hash key
 479  */
 480 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
 481                                    const char *dst)
 482 {
 483         memcpy(key->prev_hop, src, sizeof(key->prev_hop));
 484         memcpy(key->next_hop, dst, sizeof(key->next_hop));
 485 }
 486
 487 /**
 488  * batadv_nc_hash_choose() - compute the hash value for an nc path
 489  * @data: data to hash
 490  * @size: size of the hash table
 491  *
 492  * Return: the selected index in the hash table for the given data.
 493  */
 494 static u32 batadv_nc_hash_choose(const void *data, u32 size)
 495 {
 496         const struct batadv_nc_path *nc_path = data;
 497         u32 hash = 0;
 498
 499         hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
 500         hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
 501
 502         return hash % size;
 503 }
 504
 505 /**
 506  * batadv_nc_hash_compare() - comparing function used in the network coding hash
 507  *  tables
 508  * @node: node in the local table
 509  * @data2: second object to compare the node to
 510  *
 511  * Return: true if the two entry are the same, false otherwise
 512  */
 513 static bool batadv_nc_hash_compare(const struct hlist_node *node,
 514                                    const void *data2)
 515 {
 516         const struct batadv_nc_path *nc_path1, *nc_path2;
 517
 518         nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
 519         nc_path2 = data2;
 520
 521         /* Return 1 if the two keys are identical */
 522         if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
 523                 return false;
 524
 525         if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
 526                 return false;
 527
 528         return true;
 529 }
 530
 531 /**
 532  * batadv_nc_hash_find() - search for an existing nc path and return it
 533  * @hash: hash table containing the nc path
 534  * @data: search key
 535  *
 536  * Return: the nc_path if found, NULL otherwise.
 537  */
 538 static struct batadv_nc_path *
 539 batadv_nc_hash_find(struct batadv_hashtable *hash,
 540                     void *data)
 541 {
 542         struct hlist_head *head;
 543         struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
 544         int index;
 545
 546         if (!hash)
 547                 return NULL;
 548
 549         index = batadv_nc_hash_choose(data, hash->size);
 550         head = &hash->table[index];
 551
 552         rcu_read_lock();
 553         hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 554                 if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
 555                         continue;
 556
 557                 if (!kref_get_unless_zero(&nc_path->refcount))
 558                         continue;
 559
 560                 nc_path_tmp = nc_path;
 561                 break;
 562         }
 563         rcu_read_unlock();
 564
 565         return nc_path_tmp;
 566 }
 567
 568 /**
 569  * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
 570  * @nc_packet: the nc packet to send
 571  */
 572 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
 573 {
 574         batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
 575         nc_packet->skb = NULL;
 576         batadv_nc_packet_free(nc_packet, false);
 577 }
 578
 579 /**
 580  * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
 581  * @bat_priv: the bat priv with all the soft interface information
 582  * @nc_path: the nc path the packet belongs to
 583  * @nc_packet: the nc packet to be checked
 584  *
 585  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
 586  * timeout. If so, the packet is no longer kept and the entry deleted from the
 587  * queue. Has to be called with the appropriate locks.
 588  *
 589  * Return: false as soon as the entry in the fifo queue has not been timed out
 590  * yet and true otherwise.
 591  */
 592 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
 593                                     struct batadv_nc_path *nc_path,
 594                                     struct batadv_nc_packet *nc_packet)
 595 {
 596         unsigned long timeout = bat_priv->nc.max_buffer_time;
 597         bool res = false;
 598
 599         lockdep_assert_held(&nc_path->packet_list_lock);
 600
 601         /* Packets are added to tail, so the remaining packets did not time
 602          * out and we can stop processing the current queue
 603          */
 604         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 605             !batadv_has_timed_out(nc_packet->timestamp, timeout))
 606                 goto out;
 607
 608         /* purge nc packet */
 609         list_del(&nc_packet->list);
 610         batadv_nc_packet_free(nc_packet, true);
 611
 612         res = true;
 613
 614 out:
 615         return res;
 616 }
 617
 618 /**
 619  * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
 620  * @bat_priv: the bat priv with all the soft interface information
 621  * @nc_path: the nc path the packet belongs to
 622  * @nc_packet: the nc packet to be checked
 623  *
 624  * Checks whether the given nc packet has hit its forward timeout. If so, the
 625  * packet is no longer delayed, immediately sent and the entry deleted from the
 626  * queue. Has to be called with the appropriate locks.
 627  *
 628  * Return: false as soon as the entry in the fifo queue has not been timed out
 629  * yet and true otherwise.
 630  */
 631 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
 632                                 struct batadv_nc_path *nc_path,
 633                                 struct batadv_nc_packet *nc_packet)
 634 {
 635         unsigned long timeout = bat_priv->nc.max_fwd_delay;
 636
 637         lockdep_assert_held(&nc_path->packet_list_lock);
 638
 639         /* Packets are added to tail, so the remaining packets did not time
 640          * out and we can stop processing the current queue
 641          */
 642         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 643             !batadv_has_timed_out(nc_packet->timestamp, timeout))
 644                 return false;
 645
 646         /* Send packet */
 647         batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
 648         batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
 649                            nc_packet->skb->len + ETH_HLEN);
 650         list_del(&nc_packet->list);
 651         batadv_nc_send_packet(nc_packet);
 652
 653         return true;
 654 }
 655
 656 /**
 657  * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
 658  *  out nc packets
 659  * @bat_priv: the bat priv with all the soft interface information
 660  * @hash: to be processed hash table
 661  * @process_fn: Function called to process given nc packet. Should return true
 662  *              to encourage this function to proceed with the next packet.
 663  *              Otherwise the rest of the current queue is skipped.
 664  */
 665 static void
 666 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
 667                            struct batadv_hashtable *hash,
 668                            bool (*process_fn)(struct batadv_priv *,
 669                                               struct batadv_nc_path *,
 670                                               struct batadv_nc_packet *))
 671 {
 672         struct hlist_head *head;
 673         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
 674         struct batadv_nc_path *nc_path;
 675         bool ret;
 676         int i;
 677
 678         if (!hash)
 679                 return;
 680
 681         /* Loop hash table bins */
 682         for (i = 0; i < hash->size; i++) {
 683                 head = &hash->table[i];
 684
 685                 /* Loop coding paths */
 686                 rcu_read_lock();
 687                 hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 688                         /* Loop packets */
 689                         spin_lock_bh(&nc_path->packet_list_lock);
 690                         list_for_each_entry_safe(nc_packet, nc_packet_tmp,
 691                                                  &nc_path->packet_list, list) {
 692                                 ret = process_fn(bat_priv, nc_path, nc_packet);
 693                                 if (!ret)
 694                                         break;
 695                         }
 696                         spin_unlock_bh(&nc_path->packet_list_lock);
 697                 }
 698                 rcu_read_unlock();
 699         }
 700 }
 701
 702 /**
 703  * batadv_nc_worker() - periodic task for house keeping related to network
 704  *  coding
 705  * @work: kernel work struct
 706  */
 707 static void batadv_nc_worker(struct work_struct *work)
 708 {
 709         struct delayed_work *delayed_work;
 710         struct batadv_priv_nc *priv_nc;
 711         struct batadv_priv *bat_priv;
 712         unsigned long timeout;
 713
 714         delayed_work = to_delayed_work(work);
 715         priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
 716         bat_priv = container_of(priv_nc, struct batadv_priv, nc);
 717
 718         batadv_nc_purge_orig_hash(bat_priv);
 719         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
 720                               batadv_nc_to_purge_nc_path_coding);
 721         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
 722                               batadv_nc_to_purge_nc_path_decoding);
 723
 724         timeout = bat_priv->nc.max_fwd_delay;
 725
 726         if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
 727                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
 728                                            batadv_nc_fwd_flush);
 729                 bat_priv->nc.timestamp_fwd_flush = jiffies;
 730         }
 731
 732         if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
 733                                  bat_priv->nc.max_buffer_time)) {
 734                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
 735                                            batadv_nc_sniffed_purge);
 736                 bat_priv->nc.timestamp_sniffed_purge = jiffies;
 737         }
 738
 739         /* Schedule a new check */
 740         batadv_nc_start_timer(bat_priv);
 741 }
 742
 743 /**
 744  * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
 745  *  for coding or not
 746  * @bat_priv: the bat priv with all the soft interface information
 747  * @orig_node: neighboring orig node which may be used as nc candidate
 748  * @ogm_packet: incoming ogm packet also used for the checks
 749  *
 750  * Return: true if:
 751  *  1) The OGM must have the most recent sequence number.
 752  *  2) The TTL must be decremented by one and only one.
 753  *  3) The OGM must be received from the first hop from orig_node.
 754  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
 755  */
 756 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
 757                                     struct batadv_orig_node *orig_node,
 758                                     struct batadv_ogm_packet *ogm_packet)
 759 {
 760         struct batadv_orig_ifinfo *orig_ifinfo;
 761         u32 last_real_seqno;
 762         u8 last_ttl;
 763
 764         orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
 765         if (!orig_ifinfo)
 766                 return false;
 767
 768         last_ttl = orig_ifinfo->last_ttl;
 769         last_real_seqno = orig_ifinfo->last_real_seqno;
 770         batadv_orig_ifinfo_put(orig_ifinfo);
 771
 772         if (last_real_seqno != ntohl(ogm_packet->seqno))
 773                 return false;
 774         if (last_ttl != ogm_packet->ttl + 1)
 775                 return false;
 776         if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
 777                 return false;
 778         if (ogm_packet->tq < bat_priv->nc.min_tq)
 779                 return false;
 780
 781         return true;
 782 }
 783
 784 /**
 785  * batadv_nc_find_nc_node() - search for an existing nc node and return it
 786  * @orig_node: orig node originating the ogm packet
 787  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 788  *  (can be equal to orig_node)
 789  * @in_coding: traverse incoming or outgoing network coding list
 790  *
 791  * Return: the nc_node if found, NULL otherwise.
 792  */
 793 static struct batadv_nc_node *
 794 batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
 795                        struct batadv_orig_node *orig_neigh_node,
 796                        bool in_coding)
 797 {
 798         struct batadv_nc_node *nc_node, *nc_node_out = NULL;
 799         struct list_head *list;
 800
 801         if (in_coding)
 802                 list = &orig_neigh_node->in_coding_list;
 803         else
 804                 list = &orig_neigh_node->out_coding_list;
 805
 806         /* Traverse list of nc_nodes to orig_node */
 807         rcu_read_lock();
 808         list_for_each_entry_rcu(nc_node, list, list) {
 809                 if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
 810                         continue;
 811
 812                 if (!kref_get_unless_zero(&nc_node->refcount))
 813                         continue;
 814
 815                 /* Found a match */
 816                 nc_node_out = nc_node;
 817                 break;
 818         }
 819         rcu_read_unlock();
 820
 821         return nc_node_out;
 822 }
 823
 824 /**
 825  * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
 826  *  not found
 827  * @bat_priv: the bat priv with all the soft interface information
 828  * @orig_node: orig node originating the ogm packet
 829  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 830  *  (can be equal to orig_node)
 831  * @in_coding: traverse incoming or outgoing network coding list
 832  *
 833  * Return: the nc_node if found or created, NULL in case of an error.
 834  */
 835 static struct batadv_nc_node *
 836 batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
 837                       struct batadv_orig_node *orig_node,
 838                       struct batadv_orig_node *orig_neigh_node,
 839                       bool in_coding)
 840 {
 841         struct batadv_nc_node *nc_node;
 842         spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
 843         struct list_head *list;
 844
 845         /* Select ingoing or outgoing coding node */
 846         if (in_coding) {
 847                 lock = &orig_neigh_node->in_coding_list_lock;
 848                 list = &orig_neigh_node->in_coding_list;
 849         } else {
 850                 lock = &orig_neigh_node->out_coding_list_lock;
 851                 list = &orig_neigh_node->out_coding_list;
 852         }
 853
 854         spin_lock_bh(lock);
 855
 856         /* Check if nc_node is already added */
 857         nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
 858
 859         /* Node found */
 860         if (nc_node)
 861                 goto unlock;
 862
 863         nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
 864         if (!nc_node)
 865                 goto unlock;
 866
 867         /* Initialize nc_node */
 868         INIT_LIST_HEAD(&nc_node->list);
 869         kref_init(&nc_node->refcount);
 870         ether_addr_copy(nc_node->addr, orig_node->orig);
 871         kref_get(&orig_neigh_node->refcount);
 872         nc_node->orig_node = orig_neigh_node;
 873
 874         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
 875                    nc_node->addr, nc_node->orig_node->orig);
 876
 877         /* Add nc_node to orig_node */
 878         kref_get(&nc_node->refcount);
 879         list_add_tail_rcu(&nc_node->list, list);
 880
 881 unlock:
 882         spin_unlock_bh(lock);
 883
 884         return nc_node;
 885 }
 886
 887 /**
 888  * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
 889  *  structs (best called on incoming OGMs)
 890  * @bat_priv: the bat priv with all the soft interface information
 891  * @orig_node: orig node originating the ogm packet
 892  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 893  *  (can be equal to orig_node)
 894  * @ogm_packet: incoming ogm packet
 895  * @is_single_hop_neigh: orig_node is a single hop neighbor
 896  */
 897 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
 898                               struct batadv_orig_node *orig_node,
 899                               struct batadv_orig_node *orig_neigh_node,
 900                               struct batadv_ogm_packet *ogm_packet,
 901                               int is_single_hop_neigh)
 902 {
 903         struct batadv_nc_node *in_nc_node = NULL;
 904         struct batadv_nc_node *out_nc_node = NULL;
 905
 906         /* Check if network coding is enabled */
 907         if (!atomic_read(&bat_priv->network_coding))
 908                 goto out;
 909
 910         /* check if orig node is network coding enabled */
 911         if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
 912                 goto out;
 913
 914         /* accept ogms from 'good' neighbors and single hop neighbors */
 915         if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
 916             !is_single_hop_neigh)
 917                 goto out;
 918
 919         /* Add orig_node as in_nc_node on hop */
 920         in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
 921                                            orig_neigh_node, true);
 922         if (!in_nc_node)
 923                 goto out;
 924
 925         in_nc_node->last_seen = jiffies;
 926
 927         /* Add hop as out_nc_node on orig_node */
 928         out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
 929                                             orig_node, false);
 930         if (!out_nc_node)
 931                 goto out;
 932
 933         out_nc_node->last_seen = jiffies;
 934
 935 out:
 936         if (in_nc_node)
 937                 batadv_nc_node_put(in_nc_node);
 938         if (out_nc_node)
 939                 batadv_nc_node_put(out_nc_node);
 940 }
 941
 942 /**
 943  * batadv_nc_get_path() - get existing nc_path or allocate a new one
 944  * @bat_priv: the bat priv with all the soft interface information
 945  * @hash: hash table containing the nc path
 946  * @src: ethernet source address - first half of the nc path search key
 947  * @dst: ethernet destination address - second half of the nc path search key
 948  *
 949  * Return: pointer to nc_path if the path was found or created, returns NULL
 950  * on error.
 951  */
 952 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
 953                                                  struct batadv_hashtable *hash,
 954                                                  u8 *src,
 955                                                  u8 *dst)
 956 {
 957         int hash_added;
 958         struct batadv_nc_path *nc_path, nc_path_key;
 959
 960         batadv_nc_hash_key_gen(&nc_path_key, src, dst);
 961
 962         /* Search for existing nc_path */
 963         nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
 964
 965         if (nc_path) {
 966                 /* Set timestamp to delay removal of nc_path */
 967                 nc_path->last_valid = jiffies;
 968                 return nc_path;
 969         }
 970
 971         /* No existing nc_path was found; create a new */
 972         nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
 973
 974         if (!nc_path)
 975                 return NULL;
 976
 977         /* Initialize nc_path */
 978         INIT_LIST_HEAD(&nc_path->packet_list);
 979         spin_lock_init(&nc_path->packet_list_lock);
 980         kref_init(&nc_path->refcount);
 981         nc_path->last_valid = jiffies;
 982         ether_addr_copy(nc_path->next_hop, dst);
 983         ether_addr_copy(nc_path->prev_hop, src);
 984
 985         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
 986                    nc_path->prev_hop,
 987                    nc_path->next_hop);
 988
 989         /* Add nc_path to hash table */
 990         kref_get(&nc_path->refcount);
 991         hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
 992                                      batadv_nc_hash_choose, &nc_path_key,
 993                                      &nc_path->hash_entry);
 994
 995         if (hash_added < 0) {
 996                 kfree(nc_path);
 997                 return NULL;
 998         }
 999
1000         return nc_path;
1001 }
1002
1003 /**
1004  * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
1005  *  selection of a receiver with slightly lower TQ than the other
1006  * @tq: to be weighted tq value
1007  *
1008  * Return: scaled tq value
1009  */
1010 static u8 batadv_nc_random_weight_tq(u8 tq)
1011 {
1012         u8 rand_val, rand_tq;
1013
1014         get_random_bytes(&rand_val, sizeof(rand_val));
1015
1016         /* randomize the estimated packet loss (max TQ - estimated TQ) */
1017         rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
1018
1019         /* normalize the randomized packet loss */
1020         rand_tq /= BATADV_TQ_MAX_VALUE;
1021
1022         /* convert to (randomized) estimated tq again */
1023         return BATADV_TQ_MAX_VALUE - rand_tq;
1024 }
1025
1026 /**
1027  * batadv_nc_memxor() - XOR destination with source
1028  * @dst: byte array to XOR into
1029  * @src: byte array to XOR from
1030  * @len: length of destination array
1031  */
1032 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1033 {
1034         unsigned int i;
1035
1036         for (i = 0; i < len; ++i)
1037                 dst[i] ^= src[i];
1038 }
1039
1040 /**
1041  * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
1042  *  into a coded_packet and send it
1043  * @bat_priv: the bat priv with all the soft interface information
1044  * @skb: data skb to forward
1045  * @ethhdr: pointer to the ethernet header inside the skb
1046  * @nc_packet: structure containing the packet to the skb can be coded with
1047  * @neigh_node: next hop to forward packet to
1048  *
1049  * Return: true if both packets are consumed, false otherwise.
1050  */
1051 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1052                                    struct sk_buff *skb,
1053                                    struct ethhdr *ethhdr,
1054                                    struct batadv_nc_packet *nc_packet,
1055                                    struct batadv_neigh_node *neigh_node)
1056 {
1057         u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1058         struct sk_buff *skb_dest, *skb_src;
1059         struct batadv_unicast_packet *packet1;
1060         struct batadv_unicast_packet *packet2;
1061         struct batadv_coded_packet *coded_packet;
1062         struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1063         struct batadv_neigh_node *router_coding = NULL, *second_dest;
1064         struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1065         struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1066         u8 *first_source, *second_source;
1067         __be32 packet_id1, packet_id2;
1068         size_t count;
1069         bool res = false;
1070         int coding_len;
1071         int unicast_size = sizeof(*packet1);
1072         int coded_size = sizeof(*coded_packet);
1073         int header_add = coded_size - unicast_size;
1074
1075         /* TODO: do we need to consider the outgoing interface for
1076          * coded packets?
1077          */
1078         router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1079                                               BATADV_IF_DEFAULT);
1080         if (!router_neigh)
1081                 goto out;
1082
1083         router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1084                                                       BATADV_IF_DEFAULT);
1085         if (!router_neigh_ifinfo)
1086                 goto out;
1087
1088         neigh_tmp = nc_packet->neigh_node;
1089         router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1090                                                BATADV_IF_DEFAULT);
1091         if (!router_coding)
1092                 goto out;
1093
1094         router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1095                                                        BATADV_IF_DEFAULT);
1096         if (!router_coding_ifinfo)
1097                 goto out;
1098
1099         tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1100         tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1101         tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1102         tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1103
1104         /* Select one destination for the MAC-header dst-field based on
1105          * weighted TQ-values.
1106          */
1107         if (tq_weighted_neigh >= tq_weighted_coding) {
1108                 /* Destination from nc_packet is selected for MAC-header */
1109                 first_dest = nc_packet->neigh_node;
1110                 first_source = nc_packet->nc_path->prev_hop;
1111                 second_dest = neigh_node;
1112                 second_source = ethhdr->h_source;
1113                 packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1114                 packet2 = (struct batadv_unicast_packet *)skb->data;
1115                 packet_id1 = nc_packet->packet_id;
1116                 packet_id2 = batadv_skb_crc32(skb,
1117                                               skb->data + sizeof(*packet2));
1118         } else {
1119                 /* Destination for skb is selected for MAC-header */
1120                 first_dest = neigh_node;
1121                 first_source = ethhdr->h_source;
1122                 second_dest = nc_packet->neigh_node;
1123                 second_source = nc_packet->nc_path->prev_hop;
1124                 packet1 = (struct batadv_unicast_packet *)skb->data;
1125                 packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1126                 packet_id1 = batadv_skb_crc32(skb,
1127                                               skb->data + sizeof(*packet1));
1128                 packet_id2 = nc_packet->packet_id;
1129         }
1130
1131         /* Instead of zero padding the smallest data buffer, we
1132          * code into the largest.
1133          */
1134         if (skb->len <= nc_packet->skb->len) {
1135                 skb_dest = nc_packet->skb;
1136                 skb_src = skb;
1137         } else {
1138                 skb_dest = skb;
1139                 skb_src = nc_packet->skb;
1140         }
1141
1142         /* coding_len is used when decoding the packet shorter packet */
1143         coding_len = skb_src->len - unicast_size;
1144
1145         if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1146                 goto out;
1147
1148         skb_push(skb_dest, header_add);
1149
1150         coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1151         skb_reset_mac_header(skb_dest);
1152
1153         coded_packet->packet_type = BATADV_CODED;
1154         coded_packet->version = BATADV_COMPAT_VERSION;
1155         coded_packet->ttl = packet1->ttl;
1156
1157         /* Info about first unicast packet */
1158         ether_addr_copy(coded_packet->first_source, first_source);
1159         ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1160         coded_packet->first_crc = packet_id1;
1161         coded_packet->first_ttvn = packet1->ttvn;
1162
1163         /* Info about second unicast packet */
1164         ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1165         ether_addr_copy(coded_packet->second_source, second_source);
1166         ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1167         coded_packet->second_crc = packet_id2;
1168         coded_packet->second_ttl = packet2->ttl;
1169         coded_packet->second_ttvn = packet2->ttvn;
1170         coded_packet->coded_len = htons(coding_len);
1171
1172         /* This is where the magic happens: Code skb_src into skb_dest */
1173         batadv_nc_memxor(skb_dest->data + coded_size,
1174                          skb_src->data + unicast_size, coding_len);
1175
1176         /* Update counters accordingly */
1177         if (BATADV_SKB_CB(skb_src)->decoded &&
1178             BATADV_SKB_CB(skb_dest)->decoded) {
1179                 /* Both packets are recoded */
1180                 count = skb_src->len + ETH_HLEN;
1181                 count += skb_dest->len + ETH_HLEN;
1182                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1183                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1184         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1185                    !BATADV_SKB_CB(skb_dest)->decoded) {
1186                 /* Both packets are newly coded */
1187                 count = skb_src->len + ETH_HLEN;
1188                 count += skb_dest->len + ETH_HLEN;
1189                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1190                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1191         } else if (BATADV_SKB_CB(skb_src)->decoded &&
1192                    !BATADV_SKB_CB(skb_dest)->decoded) {
1193                 /* skb_src recoded and skb_dest is newly coded */
1194                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1195                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1196                                    skb_src->len + ETH_HLEN);
1197                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1198                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1199                                    skb_dest->len + ETH_HLEN);
1200         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1201                    BATADV_SKB_CB(skb_dest)->decoded) {
1202                 /* skb_src is newly coded and skb_dest is recoded */
1203                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1204                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1205                                    skb_src->len + ETH_HLEN);
1206                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1207                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1208                                    skb_dest->len + ETH_HLEN);
1209         }
1210
1211         /* skb_src is now coded into skb_dest, so free it */
1212         consume_skb(skb_src);
1213
1214         /* avoid duplicate free of skb from nc_packet */
1215         nc_packet->skb = NULL;
1216         batadv_nc_packet_free(nc_packet, false);
1217
1218         /* Send the coded packet and return true */
1219         batadv_send_unicast_skb(skb_dest, first_dest);
1220         res = true;
1221 out:
1222         if (router_neigh)
1223                 batadv_neigh_node_put(router_neigh);
1224         if (router_coding)
1225                 batadv_neigh_node_put(router_coding);
1226         if (router_neigh_ifinfo)
1227                 batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1228         if (router_coding_ifinfo)
1229                 batadv_neigh_ifinfo_put(router_coding_ifinfo);
1230         return res;
1231 }
1232
1233 /**
1234  * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
1235  * @skb: data skb to forward
1236  * @dst: destination mac address of the other skb to code with
1237  * @src: source mac address of skb
1238  *
1239  * Whenever we network code a packet we have to check whether we received it in
1240  * a network coded form. If so, we may not be able to use it for coding because
1241  * some neighbors may also have received (overheard) the packet in the network
1242  * coded form without being able to decode it. It is hard to know which of the
1243  * neighboring nodes was able to decode the packet, therefore we can only
1244  * re-code the packet if the source of the previous encoded packet is involved.
1245  * Since the source encoded the packet we can be certain it has all necessary
1246  * decode information.
1247  *
1248  * Return: true if coding of a decoded packet is allowed.
1249  */
1250 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1251 {
1252         if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1253                 return false;
1254         return true;
1255 }
1256
1257 /**
1258  * batadv_nc_path_search() - Find the coding path matching in_nc_node and
1259  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1260  * @bat_priv: the bat priv with all the soft interface information
1261  * @in_nc_node: pointer to skb next hop's neighbor nc node
1262  * @out_nc_node: pointer to skb source's neighbor nc node
1263  * @skb: data skb to forward
1264  * @eth_dst: next hop mac address of skb
1265  *
1266  * Return: true if coding of a decoded skb is allowed.
1267  */
1268 static struct batadv_nc_packet *
1269 batadv_nc_path_search(struct batadv_priv *bat_priv,
1270                       struct batadv_nc_node *in_nc_node,
1271                       struct batadv_nc_node *out_nc_node,
1272                       struct sk_buff *skb,
1273                       u8 *eth_dst)
1274 {
1275         struct batadv_nc_path *nc_path, nc_path_key;
1276         struct batadv_nc_packet *nc_packet_out = NULL;
1277         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1278         struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1279         int idx;
1280
1281         if (!hash)
1282                 return NULL;
1283
1284         /* Create almost path key */
1285         batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1286                                out_nc_node->addr);
1287         idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1288
1289         /* Check for coding opportunities in this nc_path */
1290         rcu_read_lock();
1291         hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1292                 if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1293                         continue;
1294
1295                 if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1296                         continue;
1297
1298                 spin_lock_bh(&nc_path->packet_list_lock);
1299                 if (list_empty(&nc_path->packet_list)) {
1300                         spin_unlock_bh(&nc_path->packet_list_lock);
1301                         continue;
1302                 }
1303
1304                 list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1305                                          &nc_path->packet_list, list) {
1306                         if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1307                                                            eth_dst,
1308                                                            in_nc_node->addr))
1309                                 continue;
1310
1311                         /* Coding opportunity is found! */
1312                         list_del(&nc_packet->list);
1313                         nc_packet_out = nc_packet;
1314                         break;
1315                 }
1316
1317                 spin_unlock_bh(&nc_path->packet_list_lock);
1318                 break;
1319         }
1320         rcu_read_unlock();
1321
1322         return nc_packet_out;
1323 }
1324
1325 /**
1326  * batadv_nc_skb_src_search() - Loops through the list of neighoring nodes of
1327  *  the skb's sender (may be equal to the originator).
1328  * @bat_priv: the bat priv with all the soft interface information
1329  * @skb: data skb to forward
1330  * @eth_dst: next hop mac address of skb
1331  * @eth_src: source mac address of skb
1332  * @in_nc_node: pointer to skb next hop's neighbor nc node
1333  *
1334  * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1335  */
1336 static struct batadv_nc_packet *
1337 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1338                          struct sk_buff *skb,
1339                          u8 *eth_dst,
1340                          u8 *eth_src,
1341                          struct batadv_nc_node *in_nc_node)
1342 {
1343         struct batadv_orig_node *orig_node;
1344         struct batadv_nc_node *out_nc_node;
1345         struct batadv_nc_packet *nc_packet = NULL;
1346
1347         orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1348         if (!orig_node)
1349                 return NULL;
1350
1351         rcu_read_lock();
1352         list_for_each_entry_rcu(out_nc_node,
1353                                 &orig_node->out_coding_list, list) {
1354                 /* Check if the skb is decoded and if recoding is possible */
1355                 if (!batadv_nc_skb_coding_possible(skb,
1356                                                    out_nc_node->addr, eth_src))
1357                         continue;
1358
1359                 /* Search for an opportunity in this nc_path */
1360                 nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1361                                                   out_nc_node, skb, eth_dst);
1362                 if (nc_packet)
1363                         break;
1364         }
1365         rcu_read_unlock();
1366
1367         batadv_orig_node_put(orig_node);
1368         return nc_packet;
1369 }
1370
1371 /**
1372  * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
1373  *  unicast skb before it is stored for use in later decoding
1374  * @bat_priv: the bat priv with all the soft interface information
1375  * @skb: data skb to store
1376  * @eth_dst_new: new destination mac address of skb
1377  */
1378 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1379                                               struct sk_buff *skb,
1380                                               u8 *eth_dst_new)
1381 {
1382         struct ethhdr *ethhdr;
1383
1384         /* Copy skb header to change the mac header */
1385         skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1386         if (!skb)
1387                 return;
1388
1389         /* Set the mac header as if we actually sent the packet uncoded */
1390         ethhdr = eth_hdr(skb);
1391         ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1392         ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1393
1394         /* Set data pointer to MAC header to mimic packets from our tx path */
1395         skb_push(skb, ETH_HLEN);
1396
1397         /* Add the packet to the decoding packet pool */
1398         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1399
1400         /* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1401          * our ref
1402          */
1403         consume_skb(skb);
1404 }
1405
1406 /**
1407  * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
1408  * @skb: data skb to forward
1409  * @neigh_node: next hop to forward packet to
1410  * @ethhdr: pointer to the ethernet header inside the skb
1411  *
1412  * Loops through list of neighboring nodes the next hop has a good connection to
1413  * (receives OGMs with a sufficient quality). We need to find a neighbor of our
1414  * next hop that potentially sent a packet which our next hop also received
1415  * (overheard) and has stored for later decoding.
1416  *
1417  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1418  */
1419 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1420                                      struct batadv_neigh_node *neigh_node,
1421                                      struct ethhdr *ethhdr)
1422 {
1423         struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1424         struct batadv_priv *bat_priv = netdev_priv(netdev);
1425         struct batadv_orig_node *orig_node = neigh_node->orig_node;
1426         struct batadv_nc_node *nc_node;
1427         struct batadv_nc_packet *nc_packet = NULL;
1428
1429         rcu_read_lock();
1430         list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1431                 /* Search for coding opportunity with this in_nc_node */
1432                 nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1433                                                      neigh_node->addr,
1434                                                      ethhdr->h_source, nc_node);
1435
1436                 /* Opportunity was found, so stop searching */
1437                 if (nc_packet)
1438                         break;
1439         }
1440         rcu_read_unlock();
1441
1442         if (!nc_packet)
1443                 return false;
1444
1445         /* Save packets for later decoding */
1446         batadv_nc_skb_store_before_coding(bat_priv, skb,
1447                                           neigh_node->addr);
1448         batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1449                                           nc_packet->neigh_node->addr);
1450
1451         /* Code and send packets */
1452         if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1453                                    neigh_node))
1454                 return true;
1455
1456         /* out of mem ? Coding failed - we have to free the buffered packet
1457          * to avoid memleaks. The skb passed as argument will be dealt with
1458          * by the calling function.
1459          */
1460         batadv_nc_send_packet(nc_packet);
1461         return false;
1462 }
1463
1464 /**
1465  * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
1466  * @skb: skb to add to path
1467  * @nc_path: path to add skb to
1468  * @neigh_node: next hop to forward packet to
1469  * @packet_id: checksum to identify packet
1470  *
1471  * Return: true if the packet was buffered or false in case of an error.
1472  */
1473 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1474                                       struct batadv_nc_path *nc_path,
1475                                       struct batadv_neigh_node *neigh_node,
1476                                       __be32 packet_id)
1477 {
1478         struct batadv_nc_packet *nc_packet;
1479
1480         nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1481         if (!nc_packet)
1482                 return false;
1483
1484         /* Initialize nc_packet */
1485         nc_packet->timestamp = jiffies;
1486         nc_packet->packet_id = packet_id;
1487         nc_packet->skb = skb;
1488         nc_packet->neigh_node = neigh_node;
1489         nc_packet->nc_path = nc_path;
1490
1491         /* Add coding packet to list */
1492         spin_lock_bh(&nc_path->packet_list_lock);
1493         list_add_tail(&nc_packet->list, &nc_path->packet_list);
1494         spin_unlock_bh(&nc_path->packet_list_lock);
1495
1496         return true;
1497 }
1498
1499 /**
1500  * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
1501  *  buffer
1502  * @skb: data skb to forward
1503  * @neigh_node: next hop to forward packet to
1504  *
1505  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1506  */
1507 bool batadv_nc_skb_forward(struct sk_buff *skb,
1508                            struct batadv_neigh_node *neigh_node)
1509 {
1510         const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1511         struct batadv_priv *bat_priv = netdev_priv(netdev);
1512         struct batadv_unicast_packet *packet;
1513         struct batadv_nc_path *nc_path;
1514         struct ethhdr *ethhdr = eth_hdr(skb);
1515         __be32 packet_id;
1516         u8 *payload;
1517
1518         /* Check if network coding is enabled */
1519         if (!atomic_read(&bat_priv->network_coding))
1520                 goto out;
1521
1522         /* We only handle unicast packets */
1523         payload = skb_network_header(skb);
1524         packet = (struct batadv_unicast_packet *)payload;
1525         if (packet->packet_type != BATADV_UNICAST)
1526                 goto out;
1527
1528         /* Try to find a coding opportunity and send the skb if one is found */
1529         if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1530                 return true;
1531
1532         /* Find or create a nc_path for this src-dst pair */
1533         nc_path = batadv_nc_get_path(bat_priv,
1534                                      bat_priv->nc.coding_hash,
1535                                      ethhdr->h_source,
1536                                      neigh_node->addr);
1537
1538         if (!nc_path)
1539                 goto out;
1540
1541         /* Add skb to nc_path */
1542         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1543         if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1544                 goto free_nc_path;
1545
1546         /* Packet is consumed */
1547         return true;
1548
1549 free_nc_path:
1550         batadv_nc_path_put(nc_path);
1551 out:
1552         /* Packet is not consumed */
1553         return false;
1554 }
1555
1556 /**
1557  * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
1558  *  used when decoding coded packets
1559  * @bat_priv: the bat priv with all the soft interface information
1560  * @skb: data skb to store
1561  */
1562 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1563                                       struct sk_buff *skb)
1564 {
1565         struct batadv_unicast_packet *packet;
1566         struct batadv_nc_path *nc_path;
1567         struct ethhdr *ethhdr = eth_hdr(skb);
1568         __be32 packet_id;
1569         u8 *payload;
1570
1571         /* Check if network coding is enabled */
1572         if (!atomic_read(&bat_priv->network_coding))
1573                 goto out;
1574
1575         /* Check for supported packet type */
1576         payload = skb_network_header(skb);
1577         packet = (struct batadv_unicast_packet *)payload;
1578         if (packet->packet_type != BATADV_UNICAST)
1579                 goto out;
1580
1581         /* Find existing nc_path or create a new */
1582         nc_path = batadv_nc_get_path(bat_priv,
1583                                      bat_priv->nc.decoding_hash,
1584                                      ethhdr->h_source,
1585                                      ethhdr->h_dest);
1586
1587         if (!nc_path)
1588                 goto out;
1589
1590         /* Clone skb and adjust skb->data to point at batman header */
1591         skb = skb_clone(skb, GFP_ATOMIC);
1592         if (unlikely(!skb))
1593                 goto free_nc_path;
1594
1595         if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1596                 goto free_skb;
1597
1598         if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1599                 goto free_skb;
1600
1601         /* Add skb to nc_path */
1602         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1603         if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1604                 goto free_skb;
1605
1606         batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1607         return;
1608
1609 free_skb:
1610         kfree_skb(skb);
1611 free_nc_path:
1612         batadv_nc_path_put(nc_path);
1613 out:
1614         return;
1615 }
1616
1617 /**
1618  * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
1619  *  should be saved in the decoding buffer and, if so, store it there
1620  * @bat_priv: the bat priv with all the soft interface information
1621  * @skb: unicast skb to store
1622  */
1623 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1624                                          struct sk_buff *skb)
1625 {
1626         struct ethhdr *ethhdr = eth_hdr(skb);
1627
1628         if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1629                 return;
1630
1631         /* Set data pointer to MAC header to mimic packets from our tx path */
1632         skb_push(skb, ETH_HLEN);
1633
1634         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1635 }
1636
1637 /**
1638  * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
1639  *  in nc_packet
1640  * @bat_priv: the bat priv with all the soft interface information
1641  * @skb: unicast skb to decode
1642  * @nc_packet: decode data needed to decode the skb
1643  *
1644  * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1645  * in case of an error.
1646  */
1647 static struct batadv_unicast_packet *
1648 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1649                             struct batadv_nc_packet *nc_packet)
1650 {
1651         const int h_size = sizeof(struct batadv_unicast_packet);
1652         const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1653         struct batadv_unicast_packet *unicast_packet;
1654         struct batadv_coded_packet coded_packet_tmp;
1655         struct ethhdr *ethhdr, ethhdr_tmp;
1656         u8 *orig_dest, ttl, ttvn;
1657         unsigned int coding_len;
1658         int err;
1659
1660         /* Save headers temporarily */
1661         memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1662         memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1663
1664         if (skb_cow(skb, 0) < 0)
1665                 return NULL;
1666
1667         if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1668                 return NULL;
1669
1670         /* Data points to batman header, so set mac header 14 bytes before
1671          * and network to data
1672          */
1673         skb_set_mac_header(skb, -ETH_HLEN);
1674         skb_reset_network_header(skb);
1675
1676         /* Reconstruct original mac header */
1677         ethhdr = eth_hdr(skb);
1678         *ethhdr = ethhdr_tmp;
1679
1680         /* Select the correct unicast header information based on the location
1681          * of our mac address in the coded_packet header
1682          */
1683         if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1684                 /* If we are the second destination the packet was overheard,
1685                  * so the Ethernet address must be copied to h_dest and
1686                  * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1687                  */
1688                 ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1689                 skb->pkt_type = PACKET_HOST;
1690
1691                 orig_dest = coded_packet_tmp.second_orig_dest;
1692                 ttl = coded_packet_tmp.second_ttl;
1693                 ttvn = coded_packet_tmp.second_ttvn;
1694         } else {
1695                 orig_dest = coded_packet_tmp.first_orig_dest;
1696                 ttl = coded_packet_tmp.ttl;
1697                 ttvn = coded_packet_tmp.first_ttvn;
1698         }
1699
1700         coding_len = ntohs(coded_packet_tmp.coded_len);
1701
1702         if (coding_len > skb->len)
1703                 return NULL;
1704
1705         /* Here the magic is reversed:
1706          *   extract the missing packet from the received coded packet
1707          */
1708         batadv_nc_memxor(skb->data + h_size,
1709                          nc_packet->skb->data + h_size,
1710                          coding_len);
1711
1712         /* Resize decoded skb if decoded with larger packet */
1713         if (nc_packet->skb->len > coding_len + h_size) {
1714                 err = pskb_trim_rcsum(skb, coding_len + h_size);
1715                 if (err)
1716                         return NULL;
1717         }
1718
1719         /* Create decoded unicast packet */
1720         unicast_packet = (struct batadv_unicast_packet *)skb->data;
1721         unicast_packet->packet_type = BATADV_UNICAST;
1722         unicast_packet->version = BATADV_COMPAT_VERSION;
1723         unicast_packet->ttl = ttl;
1724         ether_addr_copy(unicast_packet->dest, orig_dest);
1725         unicast_packet->ttvn = ttvn;
1726
1727         batadv_nc_packet_free(nc_packet, false);
1728         return unicast_packet;
1729 }
1730
1731 /**
1732  * batadv_nc_find_decoding_packet() - search through buffered decoding data to
1733  *  find the data needed to decode the coded packet
1734  * @bat_priv: the bat priv with all the soft interface information
1735  * @ethhdr: pointer to the ethernet header inside the coded packet
1736  * @coded: coded packet we try to find decode data for
1737  *
1738  * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1739  */
1740 static struct batadv_nc_packet *
1741 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1742                                struct ethhdr *ethhdr,
1743                                struct batadv_coded_packet *coded)
1744 {
1745         struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1746         struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1747         struct batadv_nc_path *nc_path, nc_path_key;
1748         u8 *dest, *source;
1749         __be32 packet_id;
1750         int index;
1751
1752         if (!hash)
1753                 return NULL;
1754
1755         /* Select the correct packet id based on the location of our mac-addr */
1756         dest = ethhdr->h_source;
1757         if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1758                 source = coded->second_source;
1759                 packet_id = coded->second_crc;
1760         } else {
1761                 source = coded->first_source;
1762                 packet_id = coded->first_crc;
1763         }
1764
1765         batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1766         index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1767
1768         /* Search for matching coding path */
1769         rcu_read_lock();
1770         hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1771                 /* Find matching nc_packet */
1772                 spin_lock_bh(&nc_path->packet_list_lock);
1773                 list_for_each_entry(tmp_nc_packet,
1774                                     &nc_path->packet_list, list) {
1775                         if (packet_id == tmp_nc_packet->packet_id) {
1776                                 list_del(&tmp_nc_packet->list);
1777
1778                                 nc_packet = tmp_nc_packet;
1779                                 break;
1780                         }
1781                 }
1782                 spin_unlock_bh(&nc_path->packet_list_lock);
1783
1784                 if (nc_packet)
1785                         break;
1786         }
1787         rcu_read_unlock();
1788
1789         if (!nc_packet)
1790                 batadv_dbg(BATADV_DBG_NC, bat_priv,
1791                            "No decoding packet found for %u\n", packet_id);
1792
1793         return nc_packet;
1794 }
1795
1796 /**
1797  * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
1798  *  resulting unicast packet
1799  * @skb: incoming coded packet
1800  * @recv_if: pointer to interface this packet was received on
1801  *
1802  * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1803  * otherwise.
1804  */
1805 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1806                                        struct batadv_hard_iface *recv_if)
1807 {
1808         struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1809         struct batadv_unicast_packet *unicast_packet;
1810         struct batadv_coded_packet *coded_packet;
1811         struct batadv_nc_packet *nc_packet;
1812         struct ethhdr *ethhdr;
1813         int hdr_size = sizeof(*coded_packet);
1814
1815         /* Check if network coding is enabled */
1816         if (!atomic_read(&bat_priv->network_coding))
1817                 goto free_skb;
1818
1819         /* Make sure we can access (and remove) header */
1820         if (unlikely(!pskb_may_pull(skb, hdr_size)))
1821                 goto free_skb;
1822
1823         coded_packet = (struct batadv_coded_packet *)skb->data;
1824         ethhdr = eth_hdr(skb);
1825
1826         /* Verify frame is destined for us */
1827         if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1828             !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1829                 goto free_skb;
1830
1831         /* Update stat counter */
1832         if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1833                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1834
1835         nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1836                                                    coded_packet);
1837         if (!nc_packet) {
1838                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1839                 goto free_skb;
1840         }
1841
1842         /* Make skb's linear, because decoding accesses the entire buffer */
1843         if (skb_linearize(skb) < 0)
1844                 goto free_nc_packet;
1845
1846         if (skb_linearize(nc_packet->skb) < 0)
1847                 goto free_nc_packet;
1848
1849         /* Decode the packet */
1850         unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1851         if (!unicast_packet) {
1852                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1853                 goto free_nc_packet;
1854         }
1855
1856         /* Mark packet as decoded to do correct recoding when forwarding */
1857         BATADV_SKB_CB(skb)->decoded = true;
1858         batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1859         batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1860                            skb->len + ETH_HLEN);
1861         return batadv_recv_unicast_packet(skb, recv_if);
1862
1863 free_nc_packet:
1864         batadv_nc_packet_free(nc_packet, true);
1865 free_skb:
1866         kfree_skb(skb);
1867
1868         return NET_RX_DROP;
1869 }
1870
1871 /**
1872  * batadv_nc_mesh_free() - clean up network coding memory
1873  * @bat_priv: the bat priv with all the soft interface information
1874  */
1875 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1876 {
1877         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1878         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1879         cancel_delayed_work_sync(&bat_priv->nc.work);
1880
1881         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1882         batadv_hash_destroy(bat_priv->nc.coding_hash);
1883         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1884         batadv_hash_destroy(bat_priv->nc.decoding_hash);
1885 }
1886
1887 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
1888 /**
1889  * batadv_nc_nodes_seq_print_text() - print the nc node information
1890  * @seq: seq file to print on
1891  * @offset: not used
1892  *
1893  * Return: always 0
1894  */
1895 int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
1896 {
1897         struct net_device *net_dev = (struct net_device *)seq->private;
1898         struct batadv_priv *bat_priv = netdev_priv(net_dev);
1899         struct batadv_hashtable *hash = bat_priv->orig_hash;
1900         struct batadv_hard_iface *primary_if;
1901         struct hlist_head *head;
1902         struct batadv_orig_node *orig_node;
1903         struct batadv_nc_node *nc_node;
1904         int i;
1905
1906         primary_if = batadv_seq_print_text_primary_if_get(seq);
1907         if (!primary_if)
1908                 goto out;
1909
1910         /* Traverse list of originators */
1911         for (i = 0; i < hash->size; i++) {
1912                 head = &hash->table[i];
1913
1914                 /* For each orig_node in this bin */
1915                 rcu_read_lock();
1916                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
1917                         /* no need to print the orig node if it does not have
1918                          * network coding neighbors
1919                          */
1920                         if (list_empty(&orig_node->in_coding_list) &&
1921                             list_empty(&orig_node->out_coding_list))
1922                                 continue;
1923
1924                         seq_printf(seq, "Node:      %pM\n", orig_node->orig);
1925
1926                         seq_puts(seq, " Ingoing:  ");
1927                         /* For each in_nc_node to this orig_node */
1928                         list_for_each_entry_rcu(nc_node,
1929                                                 &orig_node->in_coding_list,
1930                                                 list)
1931                                 seq_printf(seq, "%pM ",
1932                                            nc_node->addr);
1933                         seq_puts(seq, "\n Outgoing: ");
1934                         /* For out_nc_node to this orig_node */
1935                         list_for_each_entry_rcu(nc_node,
1936                                                 &orig_node->out_coding_list,
1937                                                 list)
1938                                 seq_printf(seq, "%pM ",
1939                                            nc_node->addr);
1940                         seq_puts(seq, "\n\n");
1941                 }
1942                 rcu_read_unlock();
1943         }
1944
1945 out:
1946         if (primary_if)
1947                 batadv_hardif_put(primary_if);
1948         return 0;
1949 }
1950
1951 /**
1952  * batadv_nc_init_debugfs() - create nc folder and related files in debugfs
1953  * @bat_priv: the bat priv with all the soft interface information
1954  */
1955 void batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
1956 {
1957         struct dentry *nc_dir;
1958
1959         nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
1960
1961         debugfs_create_u8("min_tq", 0644, nc_dir, &bat_priv->nc.min_tq);
1962
1963         debugfs_create_u32("max_fwd_delay", 0644, nc_dir,
1964                            &bat_priv->nc.max_fwd_delay);
1965
1966         debugfs_create_u32("max_buffer_time", 0644, nc_dir,
1967                            &bat_priv->nc.max_buffer_time);
1968 }
1969 #endif