diff options
Diffstat (limited to 'net/batman-adv/network-coding.c')
| -rw-r--r-- | net/batman-adv/network-coding.c | 1873 |
1 files changed, 1873 insertions, 0 deletions
diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c new file mode 100644 index 000000000..5f4aeeb60 --- /dev/null +++ b/net/batman-adv/network-coding.c @@ -0,0 +1,1873 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) B.A.T.M.A.N. contributors: + * + * Martin Hundebøll, Jeppe Ledet-Pedersen + */ + +#include "network-coding.h" +#include "main.h" + +#include <linux/atomic.h> +#include <linux/bitops.h> +#include <linux/byteorder/generic.h> +#include <linux/compiler.h> +#include <linux/container_of.h> +#include <linux/errno.h> +#include <linux/etherdevice.h> +#include <linux/gfp.h> +#include <linux/if_ether.h> +#include <linux/if_packet.h> +#include <linux/init.h> +#include <linux/jhash.h> +#include <linux/jiffies.h> +#include <linux/kref.h> +#include <linux/list.h> +#include <linux/lockdep.h> +#include <linux/net.h> +#include <linux/netdevice.h> +#include <linux/prandom.h> +#include <linux/printk.h> +#include <linux/rculist.h> +#include <linux/rcupdate.h> +#include <linux/skbuff.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/stddef.h> +#include <linux/string.h> +#include <linux/workqueue.h> +#include <uapi/linux/batadv_packet.h> + +#include "hash.h" +#include "log.h" +#include "originator.h" +#include "routing.h" +#include "send.h" +#include "tvlv.h" + +static struct lock_class_key batadv_nc_coding_hash_lock_class_key; +static struct lock_class_key batadv_nc_decoding_hash_lock_class_key; + +static void batadv_nc_worker(struct work_struct *work); +static int batadv_nc_recv_coded_packet(struct sk_buff *skb, + struct batadv_hard_iface *recv_if); + +/** + * batadv_nc_init() - one-time initialization for network coding + * + * Return: 0 on success or negative error number in case of failure + */ +int __init batadv_nc_init(void) +{ + /* Register our packet type */ + return batadv_recv_handler_register(BATADV_CODED, + batadv_nc_recv_coded_packet); +} + +/** + * batadv_nc_start_timer() - initialise the nc periodic worker + * @bat_priv: the bat priv with all the soft interface information + */ +static void batadv_nc_start_timer(struct batadv_priv *bat_priv) +{ + queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work, + msecs_to_jiffies(10)); +} + +/** + * batadv_nc_tvlv_container_update() - update the network coding tvlv container + * after network coding setting change + * @bat_priv: the bat priv with all the soft interface information + */ +static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv) +{ + char nc_mode; + + nc_mode = atomic_read(&bat_priv->network_coding); + + switch (nc_mode) { + case 0: + batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1); + break; + case 1: + batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1, + NULL, 0); + break; + } +} + +/** + * batadv_nc_status_update() - update the network coding tvlv container after + * network coding setting change + * @net_dev: the soft interface net device + */ +void batadv_nc_status_update(struct net_device *net_dev) +{ + struct batadv_priv *bat_priv = netdev_priv(net_dev); + + batadv_nc_tvlv_container_update(bat_priv); +} + +/** + * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container + * @bat_priv: the bat priv with all the soft interface information + * @orig: the orig_node of the ogm + * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags) + * @tvlv_value: tvlv buffer containing the gateway data + * @tvlv_value_len: tvlv buffer length + */ +static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig, + u8 flags, + void *tvlv_value, u16 tvlv_value_len) +{ + if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND) + clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities); + else + set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities); +} + +/** + * batadv_nc_mesh_init() - initialise coding hash table and start housekeeping + * @bat_priv: the bat priv with all the soft interface information + * + * Return: 0 on success or negative error number in case of failure + */ +int batadv_nc_mesh_init(struct batadv_priv *bat_priv) +{ + bat_priv->nc.timestamp_fwd_flush = jiffies; + bat_priv->nc.timestamp_sniffed_purge = jiffies; + + if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash) + return 0; + + bat_priv->nc.coding_hash = batadv_hash_new(128); + if (!bat_priv->nc.coding_hash) + goto err; + + batadv_hash_set_lock_class(bat_priv->nc.coding_hash, + &batadv_nc_coding_hash_lock_class_key); + + bat_priv->nc.decoding_hash = batadv_hash_new(128); + if (!bat_priv->nc.decoding_hash) { + batadv_hash_destroy(bat_priv->nc.coding_hash); + goto err; + } + + batadv_hash_set_lock_class(bat_priv->nc.decoding_hash, + &batadv_nc_decoding_hash_lock_class_key); + + INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker); + batadv_nc_start_timer(bat_priv); + + batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1, + NULL, BATADV_TVLV_NC, 1, + BATADV_TVLV_HANDLER_OGM_CIFNOTFND); + batadv_nc_tvlv_container_update(bat_priv); + return 0; + +err: + return -ENOMEM; +} + +/** + * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables + * @bat_priv: the bat priv with all the soft interface information + */ +void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv) +{ + atomic_set(&bat_priv->network_coding, 0); + bat_priv->nc.min_tq = 200; + bat_priv->nc.max_fwd_delay = 10; + bat_priv->nc.max_buffer_time = 200; +} + +/** + * batadv_nc_init_orig() - initialise the nc fields of an orig_node + * @orig_node: the orig_node which is going to be initialised + */ +void batadv_nc_init_orig(struct batadv_orig_node *orig_node) +{ + INIT_LIST_HEAD(&orig_node->in_coding_list); + INIT_LIST_HEAD(&orig_node->out_coding_list); + spin_lock_init(&orig_node->in_coding_list_lock); + spin_lock_init(&orig_node->out_coding_list_lock); +} + +/** + * batadv_nc_node_release() - release nc_node from lists and queue for free + * after rcu grace period + * @ref: kref pointer of the nc_node + */ +static void batadv_nc_node_release(struct kref *ref) +{ + struct batadv_nc_node *nc_node; + + nc_node = container_of(ref, struct batadv_nc_node, refcount); + + batadv_orig_node_put(nc_node->orig_node); + kfree_rcu(nc_node, rcu); +} + +/** + * batadv_nc_node_put() - decrement the nc_node refcounter and possibly + * release it + * @nc_node: nc_node to be free'd + */ +static void batadv_nc_node_put(struct batadv_nc_node *nc_node) +{ + if (!nc_node) + return; + + kref_put(&nc_node->refcount, batadv_nc_node_release); +} + +/** + * batadv_nc_path_release() - release nc_path from lists and queue for free + * after rcu grace period + * @ref: kref pointer of the nc_path + */ +static void batadv_nc_path_release(struct kref *ref) +{ + struct batadv_nc_path *nc_path; + + nc_path = container_of(ref, struct batadv_nc_path, refcount); + + kfree_rcu(nc_path, rcu); +} + +/** + * batadv_nc_path_put() - decrement the nc_path refcounter and possibly + * release it + * @nc_path: nc_path to be free'd + */ +static void batadv_nc_path_put(struct batadv_nc_path *nc_path) +{ + if (!nc_path) + return; + + kref_put(&nc_path->refcount, batadv_nc_path_release); +} + +/** + * batadv_nc_packet_free() - frees nc packet + * @nc_packet: the nc packet to free + * @dropped: whether the packet is freed because is dropped + */ +static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet, + bool dropped) +{ + if (dropped) + kfree_skb(nc_packet->skb); + else + consume_skb(nc_packet->skb); + + batadv_nc_path_put(nc_packet->nc_path); + kfree(nc_packet); +} + +/** + * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged + * @bat_priv: the bat priv with all the soft interface information + * @nc_node: the nc node to check + * + * Return: true if the entry has to be purged now, false otherwise + */ +static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv, + struct batadv_nc_node *nc_node) +{ + if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE) + return true; + + return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT); +} + +/** + * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out + * @bat_priv: the bat priv with all the soft interface information + * @nc_path: the nc path to check + * + * Return: true if the entry has to be purged now, false otherwise + */ +static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv, + struct batadv_nc_path *nc_path) +{ + if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE) + return true; + + /* purge the path when no packets has been added for 10 times the + * max_fwd_delay time + */ + return batadv_has_timed_out(nc_path->last_valid, + bat_priv->nc.max_fwd_delay * 10); +} + +/** + * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed + * out + * @bat_priv: the bat priv with all the soft interface information + * @nc_path: the nc path to check + * + * Return: true if the entry has to be purged now, false otherwise + */ +static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv, + struct batadv_nc_path *nc_path) +{ + if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE) + return true; + + /* purge the path when no packets has been added for 10 times the + * max_buffer time + */ + return batadv_has_timed_out(nc_path->last_valid, + bat_priv->nc.max_buffer_time * 10); +} + +/** + * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale + * entries + * @bat_priv: the bat priv with all the soft interface information + * @list: list of nc nodes + * @lock: nc node list lock + * @to_purge: function in charge to decide whether an entry has to be purged or + * not. This function takes the nc node as argument and has to return + * a boolean value: true if the entry has to be deleted, false + * otherwise + */ +static void +batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv, + struct list_head *list, + spinlock_t *lock, + bool (*to_purge)(struct batadv_priv *, + struct batadv_nc_node *)) +{ + struct batadv_nc_node *nc_node, *nc_node_tmp; + + /* For each nc_node in list */ + spin_lock_bh(lock); + list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) { + /* if an helper function has been passed as parameter, + * ask it if the entry has to be purged or not + */ + if (to_purge && !to_purge(bat_priv, nc_node)) + continue; + + batadv_dbg(BATADV_DBG_NC, bat_priv, + "Removing nc_node %pM -> %pM\n", + nc_node->addr, nc_node->orig_node->orig); + list_del_rcu(&nc_node->list); + batadv_nc_node_put(nc_node); + } + spin_unlock_bh(lock); +} + +/** + * batadv_nc_purge_orig() - purges all nc node data attached of the given + * originator + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: orig_node with the nc node entries to be purged + * @to_purge: function in charge to decide whether an entry has to be purged or + * not. This function takes the nc node as argument and has to return + * a boolean value: true is the entry has to be deleted, false + * otherwise + */ +void batadv_nc_purge_orig(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + bool (*to_purge)(struct batadv_priv *, + struct batadv_nc_node *)) +{ + /* Check ingoing nc_node's of this orig_node */ + batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list, + &orig_node->in_coding_list_lock, + to_purge); + + /* Check outgoing nc_node's of this orig_node */ + batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list, + &orig_node->out_coding_list_lock, + to_purge); +} + +/** + * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if + * they have timed out nc nodes + * @bat_priv: the bat priv with all the soft interface information + */ +static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv) +{ + struct batadv_hashtable *hash = bat_priv->orig_hash; + struct hlist_head *head; + struct batadv_orig_node *orig_node; + u32 i; + + if (!hash) + return; + + /* For each orig_node */ + for (i = 0; i < hash->size; i++) { + head = &hash->table[i]; + + rcu_read_lock(); + hlist_for_each_entry_rcu(orig_node, head, hash_entry) + batadv_nc_purge_orig(bat_priv, orig_node, + batadv_nc_to_purge_nc_node); + rcu_read_unlock(); + } +} + +/** + * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove + * unused ones + * @bat_priv: the bat priv with all the soft interface information + * @hash: hash table containing the nc paths to check + * @to_purge: function in charge to decide whether an entry has to be purged or + * not. This function takes the nc node as argument and has to return + * a boolean value: true is the entry has to be deleted, false + * otherwise + */ +static void batadv_nc_purge_paths(struct batadv_priv *bat_priv, + struct batadv_hashtable *hash, + bool (*to_purge)(struct batadv_priv *, + struct batadv_nc_path *)) +{ + struct hlist_head *head; + struct hlist_node *node_tmp; + struct batadv_nc_path *nc_path; + spinlock_t *lock; /* Protects lists in hash */ + u32 i; + + for (i = 0; i < hash->size; i++) { + head = &hash->table[i]; + lock = &hash->list_locks[i]; + + /* For each nc_path in this bin */ + spin_lock_bh(lock); + hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) { + /* if an helper function has been passed as parameter, + * ask it if the entry has to be purged or not + */ + if (to_purge && !to_purge(bat_priv, nc_path)) + continue; + + /* purging an non-empty nc_path should never happen, but + * is observed under high CPU load. Delay the purging + * until next iteration to allow the packet_list to be + * emptied first. + */ + if (!unlikely(list_empty(&nc_path->packet_list))) { + net_ratelimited_function(printk, + KERN_WARNING + "Skipping free of non-empty nc_path (%pM -> %pM)!\n", + nc_path->prev_hop, + nc_path->next_hop); + continue; + } + + /* nc_path is unused, so remove it */ + batadv_dbg(BATADV_DBG_NC, bat_priv, + "Remove nc_path %pM -> %pM\n", + nc_path->prev_hop, nc_path->next_hop); + hlist_del_rcu(&nc_path->hash_entry); + batadv_nc_path_put(nc_path); + } + spin_unlock_bh(lock); + } +} + +/** + * batadv_nc_hash_key_gen() - computes the nc_path hash key + * @key: buffer to hold the final hash key + * @src: source ethernet mac address going into the hash key + * @dst: destination ethernet mac address going into the hash key + */ +static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src, + const char *dst) +{ + memcpy(key->prev_hop, src, sizeof(key->prev_hop)); + memcpy(key->next_hop, dst, sizeof(key->next_hop)); +} + +/** + * batadv_nc_hash_choose() - compute the hash value for an nc path + * @data: data to hash + * @size: size of the hash table + * + * Return: the selected index in the hash table for the given data. + */ +static u32 batadv_nc_hash_choose(const void *data, u32 size) +{ + const struct batadv_nc_path *nc_path = data; + u32 hash = 0; + + hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash); + hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash); + + return hash % size; +} + +/** + * batadv_nc_hash_compare() - comparing function used in the network coding hash + * tables + * @node: node in the local table + * @data2: second object to compare the node to + * + * Return: true if the two entry are the same, false otherwise + */ +static bool batadv_nc_hash_compare(const struct hlist_node *node, + const void *data2) +{ + const struct batadv_nc_path *nc_path1, *nc_path2; + + nc_path1 = container_of(node, struct batadv_nc_path, hash_entry); + nc_path2 = data2; + + /* Return 1 if the two keys are identical */ + if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop)) + return false; + + if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop)) + return false; + + return true; +} + +/** + * batadv_nc_hash_find() - search for an existing nc path and return it + * @hash: hash table containing the nc path + * @data: search key + * + * Return: the nc_path if found, NULL otherwise. + */ +static struct batadv_nc_path * +batadv_nc_hash_find(struct batadv_hashtable *hash, + void *data) +{ + struct hlist_head *head; + struct batadv_nc_path *nc_path, *nc_path_tmp = NULL; + int index; + + if (!hash) + return NULL; + + index = batadv_nc_hash_choose(data, hash->size); + head = &hash->table[index]; + + rcu_read_lock(); + hlist_for_each_entry_rcu(nc_path, head, hash_entry) { + if (!batadv_nc_hash_compare(&nc_path->hash_entry, data)) + continue; + + if (!kref_get_unless_zero(&nc_path->refcount)) + continue; + + nc_path_tmp = nc_path; + break; + } + rcu_read_unlock(); + + return nc_path_tmp; +} + +/** + * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct + * @nc_packet: the nc packet to send + */ +static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet) +{ + batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node); + nc_packet->skb = NULL; + batadv_nc_packet_free(nc_packet, false); +} + +/** + * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet. + * @bat_priv: the bat priv with all the soft interface information + * @nc_path: the nc path the packet belongs to + * @nc_packet: the nc packet to be checked + * + * Checks whether the given sniffed (overheard) nc_packet has hit its buffering + * timeout. If so, the packet is no longer kept and the entry deleted from the + * queue. Has to be called with the appropriate locks. + * + * Return: false as soon as the entry in the fifo queue has not been timed out + * yet and true otherwise. + */ +static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv, + struct batadv_nc_path *nc_path, + struct batadv_nc_packet *nc_packet) +{ + unsigned long timeout = bat_priv->nc.max_buffer_time; + bool res = false; + + lockdep_assert_held(&nc_path->packet_list_lock); + + /* Packets are added to tail, so the remaining packets did not time + * out and we can stop processing the current queue + */ + if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE && + !batadv_has_timed_out(nc_packet->timestamp, timeout)) + goto out; + + /* purge nc packet */ + list_del(&nc_packet->list); + batadv_nc_packet_free(nc_packet, true); + + res = true; + +out: + return res; +} + +/** + * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet. + * @bat_priv: the bat priv with all the soft interface information + * @nc_path: the nc path the packet belongs to + * @nc_packet: the nc packet to be checked + * + * Checks whether the given nc packet has hit its forward timeout. If so, the + * packet is no longer delayed, immediately sent and the entry deleted from the + * queue. Has to be called with the appropriate locks. + * + * Return: false as soon as the entry in the fifo queue has not been timed out + * yet and true otherwise. + */ +static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv, + struct batadv_nc_path *nc_path, + struct batadv_nc_packet *nc_packet) +{ + unsigned long timeout = bat_priv->nc.max_fwd_delay; + + lockdep_assert_held(&nc_path->packet_list_lock); + + /* Packets are added to tail, so the remaining packets did not time + * out and we can stop processing the current queue + */ + if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE && + !batadv_has_timed_out(nc_packet->timestamp, timeout)) + return false; + + /* Send packet */ + batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD); + batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES, + nc_packet->skb->len + ETH_HLEN); + list_del(&nc_packet->list); + batadv_nc_send_packet(nc_packet); + + return true; +} + +/** + * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed + * out nc packets + * @bat_priv: the bat priv with all the soft interface information + * @hash: to be processed hash table + * @process_fn: Function called to process given nc packet. Should return true + * to encourage this function to proceed with the next packet. + * Otherwise the rest of the current queue is skipped. + */ +static void +batadv_nc_process_nc_paths(struct batadv_priv *bat_priv, + struct batadv_hashtable *hash, + bool (*process_fn)(struct batadv_priv *, + struct batadv_nc_path *, + struct batadv_nc_packet *)) +{ + struct hlist_head *head; + struct batadv_nc_packet *nc_packet, *nc_packet_tmp; + struct batadv_nc_path *nc_path; + bool ret; + int i; + + if (!hash) + return; + + /* Loop hash table bins */ + for (i = 0; i < hash->size; i++) { + head = &hash->table[i]; + + /* Loop coding paths */ + rcu_read_lock(); + hlist_for_each_entry_rcu(nc_path, head, hash_entry) { + /* Loop packets */ + spin_lock_bh(&nc_path->packet_list_lock); + list_for_each_entry_safe(nc_packet, nc_packet_tmp, + &nc_path->packet_list, list) { + ret = process_fn(bat_priv, nc_path, nc_packet); + if (!ret) + break; + } + spin_unlock_bh(&nc_path->packet_list_lock); + } + rcu_read_unlock(); + } +} + +/** + * batadv_nc_worker() - periodic task for housekeeping related to network + * coding + * @work: kernel work struct + */ +static void batadv_nc_worker(struct work_struct *work) +{ + struct delayed_work *delayed_work; + struct batadv_priv_nc *priv_nc; + struct batadv_priv *bat_priv; + unsigned long timeout; + + delayed_work = to_delayed_work(work); + priv_nc = container_of(delayed_work, struct batadv_priv_nc, work); + bat_priv = container_of(priv_nc, struct batadv_priv, nc); + + batadv_nc_purge_orig_hash(bat_priv); + batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, + batadv_nc_to_purge_nc_path_coding); + batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, + batadv_nc_to_purge_nc_path_decoding); + + timeout = bat_priv->nc.max_fwd_delay; + + if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) { + batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash, + batadv_nc_fwd_flush); + bat_priv->nc.timestamp_fwd_flush = jiffies; + } + + if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge, + bat_priv->nc.max_buffer_time)) { + batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash, + batadv_nc_sniffed_purge); + bat_priv->nc.timestamp_sniffed_purge = jiffies; + } + + /* Schedule a new check */ + batadv_nc_start_timer(bat_priv); +} + +/** + * batadv_can_nc_with_orig() - checks whether the given orig node is suitable + * for coding or not + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: neighboring orig node which may be used as nc candidate + * @ogm_packet: incoming ogm packet also used for the checks + * + * Return: true if: + * 1) The OGM must have the most recent sequence number. + * 2) The TTL must be decremented by one and only one. + * 3) The OGM must be received from the first hop from orig_node. + * 4) The TQ value of the OGM must be above bat_priv->nc.min_tq. + */ +static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + struct batadv_ogm_packet *ogm_packet) +{ + struct batadv_orig_ifinfo *orig_ifinfo; + u32 last_real_seqno; + u8 last_ttl; + + orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT); + if (!orig_ifinfo) + return false; + + last_ttl = orig_ifinfo->last_ttl; + last_real_seqno = orig_ifinfo->last_real_seqno; + batadv_orig_ifinfo_put(orig_ifinfo); + + if (last_real_seqno != ntohl(ogm_packet->seqno)) + return false; + if (last_ttl != ogm_packet->ttl + 1) + return false; + if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender)) + return false; + if (ogm_packet->tq < bat_priv->nc.min_tq) + return false; + + return true; +} + +/** + * batadv_nc_find_nc_node() - search for an existing nc node and return it + * @orig_node: orig node originating the ogm packet + * @orig_neigh_node: neighboring orig node from which we received the ogm packet + * (can be equal to orig_node) + * @in_coding: traverse incoming or outgoing network coding list + * + * Return: the nc_node if found, NULL otherwise. + */ +static struct batadv_nc_node * +batadv_nc_find_nc_node(struct batadv_orig_node *orig_node, + struct batadv_orig_node *orig_neigh_node, + bool in_coding) +{ + struct batadv_nc_node *nc_node, *nc_node_out = NULL; + struct list_head *list; + + if (in_coding) + list = &orig_neigh_node->in_coding_list; + else + list = &orig_neigh_node->out_coding_list; + + /* Traverse list of nc_nodes to orig_node */ + rcu_read_lock(); + list_for_each_entry_rcu(nc_node, list, list) { + if (!batadv_compare_eth(nc_node->addr, orig_node->orig)) + continue; + + if (!kref_get_unless_zero(&nc_node->refcount)) + continue; + + /* Found a match */ + nc_node_out = nc_node; + break; + } + rcu_read_unlock(); + + return nc_node_out; +} + +/** + * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was + * not found + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: orig node originating the ogm packet + * @orig_neigh_node: neighboring orig node from which we received the ogm packet + * (can be equal to orig_node) + * @in_coding: traverse incoming or outgoing network coding list + * + * Return: the nc_node if found or created, NULL in case of an error. + */ +static struct batadv_nc_node * +batadv_nc_get_nc_node(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + struct batadv_orig_node *orig_neigh_node, + bool in_coding) +{ + struct batadv_nc_node *nc_node; + spinlock_t *lock; /* Used to lock list selected by "int in_coding" */ + struct list_head *list; + + /* Select ingoing or outgoing coding node */ + if (in_coding) { + lock = &orig_neigh_node->in_coding_list_lock; + list = &orig_neigh_node->in_coding_list; + } else { + lock = &orig_neigh_node->out_coding_list_lock; + list = &orig_neigh_node->out_coding_list; + } + + spin_lock_bh(lock); + + /* Check if nc_node is already added */ + nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding); + + /* Node found */ + if (nc_node) + goto unlock; + + nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC); + if (!nc_node) + goto unlock; + + /* Initialize nc_node */ + INIT_LIST_HEAD(&nc_node->list); + kref_init(&nc_node->refcount); + ether_addr_copy(nc_node->addr, orig_node->orig); + kref_get(&orig_neigh_node->refcount); + nc_node->orig_node = orig_neigh_node; + + batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n", + nc_node->addr, nc_node->orig_node->orig); + + /* Add nc_node to orig_node */ + kref_get(&nc_node->refcount); + list_add_tail_rcu(&nc_node->list, list); + +unlock: + spin_unlock_bh(lock); + + return nc_node; +} + +/** + * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node + * structs (best called on incoming OGMs) + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: orig node originating the ogm packet + * @orig_neigh_node: neighboring orig node from which we received the ogm packet + * (can be equal to orig_node) + * @ogm_packet: incoming ogm packet + * @is_single_hop_neigh: orig_node is a single hop neighbor + */ +void batadv_nc_update_nc_node(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + struct batadv_orig_node *orig_neigh_node, + struct batadv_ogm_packet *ogm_packet, + int is_single_hop_neigh) +{ + struct batadv_nc_node *in_nc_node = NULL; + struct batadv_nc_node *out_nc_node = NULL; + + /* Check if network coding is enabled */ + if (!atomic_read(&bat_priv->network_coding)) + goto out; + + /* check if orig node is network coding enabled */ + if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities)) + goto out; + + /* accept ogms from 'good' neighbors and single hop neighbors */ + if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) && + !is_single_hop_neigh) + goto out; + + /* Add orig_node as in_nc_node on hop */ + in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node, + orig_neigh_node, true); + if (!in_nc_node) + goto out; + + in_nc_node->last_seen = jiffies; + + /* Add hop as out_nc_node on orig_node */ + out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node, + orig_node, false); + if (!out_nc_node) + goto out; + + out_nc_node->last_seen = jiffies; + +out: + batadv_nc_node_put(in_nc_node); + batadv_nc_node_put(out_nc_node); +} + +/** + * batadv_nc_get_path() - get existing nc_path or allocate a new one + * @bat_priv: the bat priv with all the soft interface information + * @hash: hash table containing the nc path + * @src: ethernet source address - first half of the nc path search key + * @dst: ethernet destination address - second half of the nc path search key + * + * Return: pointer to nc_path if the path was found or created, returns NULL + * on error. + */ +static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv, + struct batadv_hashtable *hash, + u8 *src, + u8 *dst) +{ + int hash_added; + struct batadv_nc_path *nc_path, nc_path_key; + + batadv_nc_hash_key_gen(&nc_path_key, src, dst); + + /* Search for existing nc_path */ + nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key); + + if (nc_path) { + /* Set timestamp to delay removal of nc_path */ + nc_path->last_valid = jiffies; + return nc_path; + } + + /* No existing nc_path was found; create a new */ + nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC); + + if (!nc_path) + return NULL; + + /* Initialize nc_path */ + INIT_LIST_HEAD(&nc_path->packet_list); + spin_lock_init(&nc_path->packet_list_lock); + kref_init(&nc_path->refcount); + nc_path->last_valid = jiffies; + ether_addr_copy(nc_path->next_hop, dst); + ether_addr_copy(nc_path->prev_hop, src); + + batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n", + nc_path->prev_hop, + nc_path->next_hop); + + /* Add nc_path to hash table */ + kref_get(&nc_path->refcount); + hash_added = batadv_hash_add(hash, batadv_nc_hash_compare, + batadv_nc_hash_choose, &nc_path_key, + &nc_path->hash_entry); + + if (hash_added < 0) { + kfree(nc_path); + return NULL; + } + + return nc_path; +} + +/** + * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair + * selection of a receiver with slightly lower TQ than the other + * @tq: to be weighted tq value + * + * Return: scaled tq value + */ +static u8 batadv_nc_random_weight_tq(u8 tq) +{ + /* randomize the estimated packet loss (max TQ - estimated TQ) */ + u8 rand_tq = prandom_u32_max(BATADV_TQ_MAX_VALUE + 1 - tq); + + /* convert to (randomized) estimated tq again */ + return BATADV_TQ_MAX_VALUE - rand_tq; +} + +/** + * batadv_nc_memxor() - XOR destination with source + * @dst: byte array to XOR into + * @src: byte array to XOR from + * @len: length of destination array + */ +static void batadv_nc_memxor(char *dst, const char *src, unsigned int len) +{ + unsigned int i; + + for (i = 0; i < len; ++i) + dst[i] ^= src[i]; +} + +/** + * batadv_nc_code_packets() - code a received unicast_packet with an nc packet + * into a coded_packet and send it + * @bat_priv: the bat priv with all the soft interface information + * @skb: data skb to forward + * @ethhdr: pointer to the ethernet header inside the skb + * @nc_packet: structure containing the packet to the skb can be coded with + * @neigh_node: next hop to forward packet to + * + * Return: true if both packets are consumed, false otherwise. + */ +static bool batadv_nc_code_packets(struct batadv_priv *bat_priv, + struct sk_buff *skb, + struct ethhdr *ethhdr, + struct batadv_nc_packet *nc_packet, + struct batadv_neigh_node *neigh_node) +{ + u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp; + struct sk_buff *skb_dest, *skb_src; + struct batadv_unicast_packet *packet1; + struct batadv_unicast_packet *packet2; + struct batadv_coded_packet *coded_packet; + struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest; + struct batadv_neigh_node *router_coding = NULL, *second_dest; + struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL; + struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL; + u8 *first_source, *second_source; + __be32 packet_id1, packet_id2; + size_t count; + bool res = false; + int coding_len; + int unicast_size = sizeof(*packet1); + int coded_size = sizeof(*coded_packet); + int header_add = coded_size - unicast_size; + + /* TODO: do we need to consider the outgoing interface for + * coded packets? + */ + router_neigh = batadv_orig_router_get(neigh_node->orig_node, + BATADV_IF_DEFAULT); + if (!router_neigh) + goto out; + + router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh, + BATADV_IF_DEFAULT); + if (!router_neigh_ifinfo) + goto out; + + neigh_tmp = nc_packet->neigh_node; + router_coding = batadv_orig_router_get(neigh_tmp->orig_node, + BATADV_IF_DEFAULT); + if (!router_coding) + goto out; + + router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding, + BATADV_IF_DEFAULT); + if (!router_coding_ifinfo) + goto out; + + tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg; + tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp); + tq_tmp = router_coding_ifinfo->bat_iv.tq_avg; + tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp); + + /* Select one destination for the MAC-header dst-field based on + * weighted TQ-values. + */ + if (tq_weighted_neigh >= tq_weighted_coding) { + /* Destination from nc_packet is selected for MAC-header */ + first_dest = nc_packet->neigh_node; + first_source = nc_packet->nc_path->prev_hop; + second_dest = neigh_node; + second_source = ethhdr->h_source; + packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data; + packet2 = (struct batadv_unicast_packet *)skb->data; + packet_id1 = nc_packet->packet_id; + packet_id2 = batadv_skb_crc32(skb, + skb->data + sizeof(*packet2)); + } else { + /* Destination for skb is selected for MAC-header */ + first_dest = neigh_node; + first_source = ethhdr->h_source; + second_dest = nc_packet->neigh_node; + second_source = nc_packet->nc_path->prev_hop; + packet1 = (struct batadv_unicast_packet *)skb->data; + packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data; + packet_id1 = batadv_skb_crc32(skb, + skb->data + sizeof(*packet1)); + packet_id2 = nc_packet->packet_id; + } + + /* Instead of zero padding the smallest data buffer, we + * code into the largest. + */ + if (skb->len <= nc_packet->skb->len) { + skb_dest = nc_packet->skb; + skb_src = skb; + } else { + skb_dest = skb; + skb_src = nc_packet->skb; + } + + /* coding_len is used when decoding the packet shorter packet */ + coding_len = skb_src->len - unicast_size; + + if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0) + goto out; + + skb_push(skb_dest, header_add); + + coded_packet = (struct batadv_coded_packet *)skb_dest->data; + skb_reset_mac_header(skb_dest); + + coded_packet->packet_type = BATADV_CODED; + coded_packet->version = BATADV_COMPAT_VERSION; + coded_packet->ttl = packet1->ttl; + + /* Info about first unicast packet */ + ether_addr_copy(coded_packet->first_source, first_source); + ether_addr_copy(coded_packet->first_orig_dest, packet1->dest); + coded_packet->first_crc = packet_id1; + coded_packet->first_ttvn = packet1->ttvn; + + /* Info about second unicast packet */ + ether_addr_copy(coded_packet->second_dest, second_dest->addr); + ether_addr_copy(coded_packet->second_source, second_source); + ether_addr_copy(coded_packet->second_orig_dest, packet2->dest); + coded_packet->second_crc = packet_id2; + coded_packet->second_ttl = packet2->ttl; + coded_packet->second_ttvn = packet2->ttvn; + coded_packet->coded_len = htons(coding_len); + + /* This is where the magic happens: Code skb_src into skb_dest */ + batadv_nc_memxor(skb_dest->data + coded_size, + skb_src->data + unicast_size, coding_len); + + /* Update counters accordingly */ + if (BATADV_SKB_CB(skb_src)->decoded && + BATADV_SKB_CB(skb_dest)->decoded) { + /* Both packets are recoded */ + count = skb_src->len + ETH_HLEN; + count += skb_dest->len + ETH_HLEN; + batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2); + batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count); + } else if (!BATADV_SKB_CB(skb_src)->decoded && + !BATADV_SKB_CB(skb_dest)->decoded) { + /* Both packets are newly coded */ + count = skb_src->len + ETH_HLEN; + count += skb_dest->len + ETH_HLEN; + batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2); + batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count); + } else if (BATADV_SKB_CB(skb_src)->decoded && + !BATADV_SKB_CB(skb_dest)->decoded) { + /* skb_src recoded and skb_dest is newly coded */ + batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE); + batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, + skb_src->len + ETH_HLEN); + batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE); + batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, + skb_dest->len + ETH_HLEN); + } else if (!BATADV_SKB_CB(skb_src)->decoded && + BATADV_SKB_CB(skb_dest)->decoded) { + /* skb_src is newly coded and skb_dest is recoded */ + batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE); + batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, + skb_src->len + ETH_HLEN); + batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE); + batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, + skb_dest->len + ETH_HLEN); + } + + /* skb_src is now coded into skb_dest, so free it */ + consume_skb(skb_src); + + /* avoid duplicate free of skb from nc_packet */ + nc_packet->skb = NULL; + batadv_nc_packet_free(nc_packet, false); + + /* Send the coded packet and return true */ + batadv_send_unicast_skb(skb_dest, first_dest); + res = true; +out: + batadv_neigh_node_put(router_neigh); + batadv_neigh_node_put(router_coding); + batadv_neigh_ifinfo_put(router_neigh_ifinfo); + batadv_neigh_ifinfo_put(router_coding_ifinfo); + return res; +} + +/** + * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst. + * @skb: data skb to forward + * @dst: destination mac address of the other skb to code with + * @src: source mac address of skb + * + * Whenever we network code a packet we have to check whether we received it in + * a network coded form. If so, we may not be able to use it for coding because + * some neighbors may also have received (overheard) the packet in the network + * coded form without being able to decode it. It is hard to know which of the + * neighboring nodes was able to decode the packet, therefore we can only + * re-code the packet if the source of the previous encoded packet is involved. + * Since the source encoded the packet we can be certain it has all necessary + * decode information. + * + * Return: true if coding of a decoded packet is allowed. + */ +static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src) +{ + if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src)) + return false; + return true; +} + +/** + * batadv_nc_path_search() - Find the coding path matching in_nc_node and + * out_nc_node to retrieve a buffered packet that can be used for coding. + * @bat_priv: the bat priv with all the soft interface information + * @in_nc_node: pointer to skb next hop's neighbor nc node + * @out_nc_node: pointer to skb source's neighbor nc node + * @skb: data skb to forward + * @eth_dst: next hop mac address of skb + * + * Return: true if coding of a decoded skb is allowed. + */ +static struct batadv_nc_packet * +batadv_nc_path_search(struct batadv_priv *bat_priv, + struct batadv_nc_node *in_nc_node, + struct batadv_nc_node *out_nc_node, + struct sk_buff *skb, + u8 *eth_dst) +{ + struct batadv_nc_path *nc_path, nc_path_key; + struct batadv_nc_packet *nc_packet_out = NULL; + struct batadv_nc_packet *nc_packet, *nc_packet_tmp; + struct batadv_hashtable *hash = bat_priv->nc.coding_hash; + int idx; + + if (!hash) + return NULL; + + /* Create almost path key */ + batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr, + out_nc_node->addr); + idx = batadv_nc_hash_choose(&nc_path_key, hash->size); + + /* Check for coding opportunities in this nc_path */ + rcu_read_lock(); + hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) { + if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr)) + continue; + + if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr)) + continue; + + spin_lock_bh(&nc_path->packet_list_lock); + if (list_empty(&nc_path->packet_list)) { + spin_unlock_bh(&nc_path->packet_list_lock); + continue; + } + + list_for_each_entry_safe(nc_packet, nc_packet_tmp, + &nc_path->packet_list, list) { + if (!batadv_nc_skb_coding_possible(nc_packet->skb, + eth_dst, + in_nc_node->addr)) + continue; + + /* Coding opportunity is found! */ + list_del(&nc_packet->list); + nc_packet_out = nc_packet; + break; + } + + spin_unlock_bh(&nc_path->packet_list_lock); + break; + } + rcu_read_unlock(); + + return nc_packet_out; +} + +/** + * batadv_nc_skb_src_search() - Loops through the list of neighboring nodes of + * the skb's sender (may be equal to the originator). + * @bat_priv: the bat priv with all the soft interface information + * @skb: data skb to forward + * @eth_dst: next hop mac address of skb + * @eth_src: source mac address of skb + * @in_nc_node: pointer to skb next hop's neighbor nc node + * + * Return: an nc packet if a suitable coding packet was found, NULL otherwise. + */ +static struct batadv_nc_packet * +batadv_nc_skb_src_search(struct batadv_priv *bat_priv, + struct sk_buff *skb, + u8 *eth_dst, + u8 *eth_src, + struct batadv_nc_node *in_nc_node) +{ + struct batadv_orig_node *orig_node; + struct batadv_nc_node *out_nc_node; + struct batadv_nc_packet *nc_packet = NULL; + + orig_node = batadv_orig_hash_find(bat_priv, eth_src); + if (!orig_node) + return NULL; + + rcu_read_lock(); + list_for_each_entry_rcu(out_nc_node, + &orig_node->out_coding_list, list) { + /* Check if the skb is decoded and if recoding is possible */ + if (!batadv_nc_skb_coding_possible(skb, + out_nc_node->addr, eth_src)) + continue; + + /* Search for an opportunity in this nc_path */ + nc_packet = batadv_nc_path_search(bat_priv, in_nc_node, + out_nc_node, skb, eth_dst); + if (nc_packet) + break; + } + rcu_read_unlock(); + + batadv_orig_node_put(orig_node); + return nc_packet; +} + +/** + * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the + * unicast skb before it is stored for use in later decoding + * @bat_priv: the bat priv with all the soft interface information + * @skb: data skb to store + * @eth_dst_new: new destination mac address of skb + */ +static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv, + struct sk_buff *skb, + u8 *eth_dst_new) +{ + struct ethhdr *ethhdr; + + /* Copy skb header to change the mac header */ + skb = pskb_copy_for_clone(skb, GFP_ATOMIC); + if (!skb) + return; + + /* Set the mac header as if we actually sent the packet uncoded */ + ethhdr = eth_hdr(skb); + ether_addr_copy(ethhdr->h_source, ethhdr->h_dest); + ether_addr_copy(ethhdr->h_dest, eth_dst_new); + + /* Set data pointer to MAC header to mimic packets from our tx path */ + skb_push(skb, ETH_HLEN); + + /* Add the packet to the decoding packet pool */ + batadv_nc_skb_store_for_decoding(bat_priv, skb); + + /* batadv_nc_skb_store_for_decoding() clones the skb, so we must free + * our ref + */ + consume_skb(skb); +} + +/** + * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst. + * @skb: data skb to forward + * @neigh_node: next hop to forward packet to + * @ethhdr: pointer to the ethernet header inside the skb + * + * Loops through the list of neighboring nodes the next hop has a good + * connection to (receives OGMs with a sufficient quality). We need to find a + * neighbor of our next hop that potentially sent a packet which our next hop + * also received (overheard) and has stored for later decoding. + * + * Return: true if the skb was consumed (encoded packet sent) or false otherwise + */ +static bool batadv_nc_skb_dst_search(struct sk_buff *skb, + struct batadv_neigh_node *neigh_node, + struct ethhdr *ethhdr) +{ + struct net_device *netdev = neigh_node->if_incoming->soft_iface; + struct batadv_priv *bat_priv = netdev_priv(netdev); + struct batadv_orig_node *orig_node = neigh_node->orig_node; + struct batadv_nc_node *nc_node; + struct batadv_nc_packet *nc_packet = NULL; + + rcu_read_lock(); + list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) { + /* Search for coding opportunity with this in_nc_node */ + nc_packet = batadv_nc_skb_src_search(bat_priv, skb, + neigh_node->addr, + ethhdr->h_source, nc_node); + + /* Opportunity was found, so stop searching */ + if (nc_packet) + break; + } + rcu_read_unlock(); + + if (!nc_packet) + return false; + + /* Save packets for later decoding */ + batadv_nc_skb_store_before_coding(bat_priv, skb, + neigh_node->addr); + batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb, + nc_packet->neigh_node->addr); + + /* Code and send packets */ + if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet, + neigh_node)) + return true; + + /* out of mem ? Coding failed - we have to free the buffered packet + * to avoid memleaks. The skb passed as argument will be dealt with + * by the calling function. + */ + batadv_nc_send_packet(nc_packet); + return false; +} + +/** + * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding + * @skb: skb to add to path + * @nc_path: path to add skb to + * @neigh_node: next hop to forward packet to + * @packet_id: checksum to identify packet + * + * Return: true if the packet was buffered or false in case of an error. + */ +static bool batadv_nc_skb_add_to_path(struct sk_buff *skb, + struct batadv_nc_path *nc_path, + struct batadv_neigh_node *neigh_node, + __be32 packet_id) +{ + struct batadv_nc_packet *nc_packet; + + nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC); + if (!nc_packet) + return false; + + /* Initialize nc_packet */ + nc_packet->timestamp = jiffies; + nc_packet->packet_id = packet_id; + nc_packet->skb = skb; + nc_packet->neigh_node = neigh_node; + nc_packet->nc_path = nc_path; + + /* Add coding packet to list */ + spin_lock_bh(&nc_path->packet_list_lock); + list_add_tail(&nc_packet->list, &nc_path->packet_list); + spin_unlock_bh(&nc_path->packet_list_lock); + + return true; +} + +/** + * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet + * buffer + * @skb: data skb to forward + * @neigh_node: next hop to forward packet to + * + * Return: true if the skb was consumed (encoded packet sent) or false otherwise + */ +bool batadv_nc_skb_forward(struct sk_buff *skb, + struct batadv_neigh_node *neigh_node) +{ + const struct net_device *netdev = neigh_node->if_incoming->soft_iface; + struct batadv_priv *bat_priv = netdev_priv(netdev); + struct batadv_unicast_packet *packet; + struct batadv_nc_path *nc_path; + struct ethhdr *ethhdr = eth_hdr(skb); + __be32 packet_id; + u8 *payload; + + /* Check if network coding is enabled */ + if (!atomic_read(&bat_priv->network_coding)) + goto out; + + /* We only handle unicast packets */ + payload = skb_network_header(skb); + packet = (struct batadv_unicast_packet *)payload; + if (packet->packet_type != BATADV_UNICAST) + goto out; + + /* Try to find a coding opportunity and send the skb if one is found */ + if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr)) + return true; + + /* Find or create a nc_path for this src-dst pair */ + nc_path = batadv_nc_get_path(bat_priv, + bat_priv->nc.coding_hash, + ethhdr->h_source, + neigh_node->addr); + + if (!nc_path) + goto out; + + /* Add skb to nc_path */ + packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet)); + if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id)) + goto free_nc_path; + + /* Packet is consumed */ + return true; + +free_nc_path: + batadv_nc_path_put(nc_path); +out: + /* Packet is not consumed */ + return false; +} + +/** + * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be + * used when decoding coded packets + * @bat_priv: the bat priv with all the soft interface information + * @skb: data skb to store + */ +void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv, + struct sk_buff *skb) +{ + struct batadv_unicast_packet *packet; + struct batadv_nc_path *nc_path; + struct ethhdr *ethhdr = eth_hdr(skb); + __be32 packet_id; + u8 *payload; + + /* Check if network coding is enabled */ + if (!atomic_read(&bat_priv->network_coding)) + goto out; + + /* Check for supported packet type */ + payload = skb_network_header(skb); + packet = (struct batadv_unicast_packet *)payload; + if (packet->packet_type != BATADV_UNICAST) + goto out; + + /* Find existing nc_path or create a new */ + nc_path = batadv_nc_get_path(bat_priv, + bat_priv->nc.decoding_hash, + ethhdr->h_source, + ethhdr->h_dest); + + if (!nc_path) + goto out; + + /* Clone skb and adjust skb->data to point at batman header */ + skb = skb_clone(skb, GFP_ATOMIC); + if (unlikely(!skb)) + goto free_nc_path; + + if (unlikely(!pskb_may_pull(skb, ETH_HLEN))) + goto free_skb; + + if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN))) + goto free_skb; + + /* Add skb to nc_path */ + packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet)); + if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id)) + goto free_skb; + + batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER); + return; + +free_skb: + kfree_skb(skb); +free_nc_path: + batadv_nc_path_put(nc_path); +out: + return; +} + +/** + * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet + * should be saved in the decoding buffer and, if so, store it there + * @bat_priv: the bat priv with all the soft interface information + * @skb: unicast skb to store + */ +void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv, + struct sk_buff *skb) +{ + struct ethhdr *ethhdr = eth_hdr(skb); + + if (batadv_is_my_mac(bat_priv, ethhdr->h_dest)) + return; + + /* Set data pointer to MAC header to mimic packets from our tx path */ + skb_push(skb, ETH_HLEN); + + batadv_nc_skb_store_for_decoding(bat_priv, skb); +} + +/** + * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored + * in nc_packet + * @bat_priv: the bat priv with all the soft interface information + * @skb: unicast skb to decode + * @nc_packet: decode data needed to decode the skb + * + * Return: pointer to decoded unicast packet if the packet was decoded or NULL + * in case of an error. + */ +static struct batadv_unicast_packet * +batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb, + struct batadv_nc_packet *nc_packet) +{ + const int h_size = sizeof(struct batadv_unicast_packet); + const int h_diff = sizeof(struct batadv_coded_packet) - h_size; + struct batadv_unicast_packet *unicast_packet; + struct batadv_coded_packet coded_packet_tmp; + struct ethhdr *ethhdr, ethhdr_tmp; + u8 *orig_dest, ttl, ttvn; + unsigned int coding_len; + int err; + + /* Save headers temporarily */ + memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp)); + memcpy(ðhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp)); + + if (skb_cow(skb, 0) < 0) + return NULL; + + if (unlikely(!skb_pull_rcsum(skb, h_diff))) + return NULL; + + /* Data points to batman header, so set mac header 14 bytes before + * and network to data + */ + skb_set_mac_header(skb, -ETH_HLEN); + skb_reset_network_header(skb); + + /* Reconstruct original mac header */ + ethhdr = eth_hdr(skb); + *ethhdr = ethhdr_tmp; + + /* Select the correct unicast header information based on the location + * of our mac address in the coded_packet header + */ + if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) { + /* If we are the second destination the packet was overheard, + * so the Ethernet address must be copied to h_dest and + * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST + */ + ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest); + skb->pkt_type = PACKET_HOST; + + orig_dest = coded_packet_tmp.second_orig_dest; + ttl = coded_packet_tmp.second_ttl; + ttvn = coded_packet_tmp.second_ttvn; + } else { + orig_dest = coded_packet_tmp.first_orig_dest; + ttl = coded_packet_tmp.ttl; + ttvn = coded_packet_tmp.first_ttvn; + } + + coding_len = ntohs(coded_packet_tmp.coded_len); + + if (coding_len > skb->len) + return NULL; + + /* Here the magic is reversed: + * extract the missing packet from the received coded packet + */ + batadv_nc_memxor(skb->data + h_size, + nc_packet->skb->data + h_size, + coding_len); + + /* Resize decoded skb if decoded with larger packet */ + if (nc_packet->skb->len > coding_len + h_size) { + err = pskb_trim_rcsum(skb, coding_len + h_size); + if (err) + return NULL; + } + + /* Create decoded unicast packet */ + unicast_packet = (struct batadv_unicast_packet *)skb->data; + unicast_packet->packet_type = BATADV_UNICAST; + unicast_packet->version = BATADV_COMPAT_VERSION; + unicast_packet->ttl = ttl; + ether_addr_copy(unicast_packet->dest, orig_dest); + unicast_packet->ttvn = ttvn; + + batadv_nc_packet_free(nc_packet, false); + return unicast_packet; +} + +/** + * batadv_nc_find_decoding_packet() - search through buffered decoding data to + * find the data needed to decode the coded packet + * @bat_priv: the bat priv with all the soft interface information + * @ethhdr: pointer to the ethernet header inside the coded packet + * @coded: coded packet we try to find decode data for + * + * Return: pointer to nc packet if the needed data was found or NULL otherwise. + */ +static struct batadv_nc_packet * +batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv, + struct ethhdr *ethhdr, + struct batadv_coded_packet *coded) +{ + struct batadv_hashtable *hash = bat_priv->nc.decoding_hash; + struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL; + struct batadv_nc_path *nc_path, nc_path_key; + u8 *dest, *source; + __be32 packet_id; + int index; + + if (!hash) + return NULL; + + /* Select the correct packet id based on the location of our mac-addr */ + dest = ethhdr->h_source; + if (!batadv_is_my_mac(bat_priv, coded->second_dest)) { + source = coded->second_source; + packet_id = coded->second_crc; + } else { + source = coded->first_source; + packet_id = coded->first_crc; + } + + batadv_nc_hash_key_gen(&nc_path_key, source, dest); + index = batadv_nc_hash_choose(&nc_path_key, hash->size); + + /* Search for matching coding path */ + rcu_read_lock(); + hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) { + /* Find matching nc_packet */ + spin_lock_bh(&nc_path->packet_list_lock); + list_for_each_entry(tmp_nc_packet, + &nc_path->packet_list, list) { + if (packet_id == tmp_nc_packet->packet_id) { + list_del(&tmp_nc_packet->list); + + nc_packet = tmp_nc_packet; + break; + } + } + spin_unlock_bh(&nc_path->packet_list_lock); + + if (nc_packet) + break; + } + rcu_read_unlock(); + + if (!nc_packet) + batadv_dbg(BATADV_DBG_NC, bat_priv, + "No decoding packet found for %u\n", packet_id); + + return nc_packet; +} + +/** + * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the + * resulting unicast packet + * @skb: incoming coded packet + * @recv_if: pointer to interface this packet was received on + * + * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP + * otherwise. + */ +static int batadv_nc_recv_coded_packet(struct sk_buff *skb, + struct batadv_hard_iface *recv_if) +{ + struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface); + struct batadv_unicast_packet *unicast_packet; + struct batadv_coded_packet *coded_packet; + struct batadv_nc_packet *nc_packet; + struct ethhdr *ethhdr; + int hdr_size = sizeof(*coded_packet); + + /* Check if network coding is enabled */ + if (!atomic_read(&bat_priv->network_coding)) + goto free_skb; + + /* Make sure we can access (and remove) header */ + if (unlikely(!pskb_may_pull(skb, hdr_size))) + goto free_skb; + + coded_packet = (struct batadv_coded_packet *)skb->data; + ethhdr = eth_hdr(skb); + + /* Verify frame is destined for us */ + if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) && + !batadv_is_my_mac(bat_priv, coded_packet->second_dest)) + goto free_skb; + + /* Update stat counter */ + if (batadv_is_my_mac(bat_priv, coded_packet->second_dest)) + batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED); + + nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr, + coded_packet); + if (!nc_packet) { + batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED); + goto free_skb; + } + + /* Make skb's linear, because decoding accesses the entire buffer */ + if (skb_linearize(skb) < 0) + goto free_nc_packet; + + if (skb_linearize(nc_packet->skb) < 0) + goto free_nc_packet; + + /* Decode the packet */ + unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet); + if (!unicast_packet) { + batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED); + goto free_nc_packet; + } + + /* Mark packet as decoded to do correct recoding when forwarding */ + BATADV_SKB_CB(skb)->decoded = true; + batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE); + batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES, + skb->len + ETH_HLEN); + return batadv_recv_unicast_packet(skb, recv_if); + +free_nc_packet: + batadv_nc_packet_free(nc_packet, true); +free_skb: + kfree_skb(skb); + + return NET_RX_DROP; +} + +/** + * batadv_nc_mesh_free() - clean up network coding memory + * @bat_priv: the bat priv with all the soft interface information + */ +void batadv_nc_mesh_free(struct batadv_priv *bat_priv) +{ + batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1); + batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1); + cancel_delayed_work_sync(&bat_priv->nc.work); + + batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL); + batadv_hash_destroy(bat_priv->nc.coding_hash); + batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL); + batadv_hash_destroy(bat_priv->nc.decoding_hash); +} |