// SPDX-License-Identifier: GPL-2.0

  /* Copyright (C) 2011-2020  B.A.T.M.A.N. contributors:

   *
   * Simon Wunderlich

   */

  #include "bridge_loop_avoidance.h"

  #include "main.h"

  #include <linux/atomic.h>
  #include <linux/byteorder/generic.h>
  #include <linux/compiler.h>

  #include <linux/crc16.h>

  #include <linux/errno.h>
  #include <linux/etherdevice.h>

  #include <linux/gfp.h>

  #include <linux/if_arp.h>

  #include <linux/if_ether.h>

  #include <linux/if_vlan.h>

  #include <linux/jhash.h>
  #include <linux/jiffies.h>
  #include <linux/kernel.h>

  #include <linux/kref.h>

  #include <linux/list.h>
  #include <linux/lockdep.h>
  #include <linux/netdevice.h>

  #include <linux/netlink.h>

  #include <linux/preempt.h>

  #include <linux/rculist.h>
  #include <linux/rcupdate.h>
  #include <linux/seq_file.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 <net/arp.h>

  #include <net/genetlink.h>
  #include <net/netlink.h>
  #include <net/sock.h>

  #include <uapi/linux/batadv_packet.h>

  #include <uapi/linux/batman_adv.h>

  
  #include "hard-interface.h"
  #include "hash.h"

  #include "log.h"

  #include "netlink.h"

  #include "originator.h"

  #include "soft-interface.h"

  #include "translation-table.h"

  static const u8 batadv_announce_mac[4] = {0x43, 0x05, 0x43, 0x05};

  static void batadv_bla_periodic_work(struct work_struct *work);

  static void
  batadv_bla_send_announce(struct batadv_priv *bat_priv,
  			 struct batadv_bla_backbone_gw *backbone_gw);

  /**

   * batadv_choose_claim() - choose the right bucket for a claim.

   * @data: data to hash
   * @size: size of the hash table

   *

   * Return: the hash index of the claim

   */

  static inline u32 batadv_choose_claim(const void *data, u32 size)

  {

  	struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;

  	u32 hash = 0;

  	hash = jhash(&claim->addr, sizeof(claim->addr), hash);
  	hash = jhash(&claim->vid, sizeof(claim->vid), hash);

  
  	return hash % size;
  }

  /**

   * batadv_choose_backbone_gw() - choose the right bucket for a backbone gateway.

   * @data: data to hash
   * @size: size of the hash table

   *

   * Return: the hash index of the backbone gateway

   */

  static inline u32 batadv_choose_backbone_gw(const void *data, u32 size)

  {

  	const struct batadv_bla_backbone_gw *gw;

  	u32 hash = 0;

  	gw = (struct batadv_bla_backbone_gw *)data;
  	hash = jhash(&gw->orig, sizeof(gw->orig), hash);
  	hash = jhash(&gw->vid, sizeof(gw->vid), hash);

  
  	return hash % size;
  }

  /**

   * batadv_compare_backbone_gw() - compare address and vid of two backbone gws

   * @node: list node of the first entry to compare
   * @data2: pointer to the second backbone gateway
   *

   * Return: true if the backbones have the same data, false otherwise

   */

  static bool batadv_compare_backbone_gw(const struct hlist_node *node,
  				       const void *data2)

  {

  	const void *data1 = container_of(node, struct batadv_bla_backbone_gw,

  					 hash_entry);

  	const struct batadv_bla_backbone_gw *gw1 = data1;
  	const struct batadv_bla_backbone_gw *gw2 = data2;

  	if (!batadv_compare_eth(gw1->orig, gw2->orig))

  		return false;

  
  	if (gw1->vid != gw2->vid)

  		return false;

  	return true;

  }

  /**

   * batadv_compare_claim() - compare address and vid of two claims

   * @node: list node of the first entry to compare
   * @data2: pointer to the second claims
   *

   * Return: true if the claim have the same data, 0 otherwise

   */

  static bool batadv_compare_claim(const struct hlist_node *node,
  				 const void *data2)

  {

  	const void *data1 = container_of(node, struct batadv_bla_claim,

  					 hash_entry);

  	const struct batadv_bla_claim *cl1 = data1;
  	const struct batadv_bla_claim *cl2 = data2;

  
  	if (!batadv_compare_eth(cl1->addr, cl2->addr))

  		return false;

  
  	if (cl1->vid != cl2->vid)

  		return false;

  	return true;

  }

  /**

   * batadv_backbone_gw_release() - release backbone gw from lists and queue for

   *  free after rcu grace period
   * @ref: kref pointer of the backbone gw
   */
  static void batadv_backbone_gw_release(struct kref *ref)
  {
  	struct batadv_bla_backbone_gw *backbone_gw;
  
  	backbone_gw = container_of(ref, struct batadv_bla_backbone_gw,
  				   refcount);
  
  	kfree_rcu(backbone_gw, rcu);
  }
  
  /**

   * batadv_backbone_gw_put() - decrement the backbone gw refcounter and possibly

   *  release it

   * @backbone_gw: backbone gateway to be free'd
   */

  static void batadv_backbone_gw_put(struct batadv_bla_backbone_gw *backbone_gw)

  {

  	kref_put(&backbone_gw->refcount, batadv_backbone_gw_release);

  }

  /**

   * batadv_claim_release() - release claim from lists and queue for free after
   *  rcu grace period

   * @ref: kref pointer of the claim
   */

  static void batadv_claim_release(struct kref *ref)

  {

  	struct batadv_bla_claim *claim;

  	struct batadv_bla_backbone_gw *old_backbone_gw;

  
  	claim = container_of(ref, struct batadv_bla_claim, refcount);

  	spin_lock_bh(&claim->backbone_lock);
  	old_backbone_gw = claim->backbone_gw;
  	claim->backbone_gw = NULL;
  	spin_unlock_bh(&claim->backbone_lock);
  
  	spin_lock_bh(&old_backbone_gw->crc_lock);
  	old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
  	spin_unlock_bh(&old_backbone_gw->crc_lock);
  
  	batadv_backbone_gw_put(old_backbone_gw);

  	kfree_rcu(claim, rcu);

  }

  /**

   * batadv_claim_put() - decrement the claim refcounter and possibly release it

   * @claim: claim to be free'd
   */

  static void batadv_claim_put(struct batadv_bla_claim *claim)

  {

  	kref_put(&claim->refcount, batadv_claim_release);

  }

  /**

   * batadv_claim_hash_find() - looks for a claim in the claim hash

   * @bat_priv: the bat priv with all the soft interface information

   * @data: search data (may be local/static data)
   *

   * Return: claim if found or NULL otherwise.

   */

  static struct batadv_bla_claim *
  batadv_claim_hash_find(struct batadv_priv *bat_priv,
  		       struct batadv_bla_claim *data)

  {

  	struct batadv_hashtable *hash = bat_priv->bla.claim_hash;

  	struct hlist_head *head;

  	struct batadv_bla_claim *claim;
  	struct batadv_bla_claim *claim_tmp = NULL;

  	int index;
  
  	if (!hash)
  		return NULL;

  	index = batadv_choose_claim(data, hash->size);

  	head = &hash->table[index];
  
  	rcu_read_lock();

  	hlist_for_each_entry_rcu(claim, head, hash_entry) {

  		if (!batadv_compare_claim(&claim->hash_entry, data))

  			continue;

  		if (!kref_get_unless_zero(&claim->refcount))

  			continue;
  
  		claim_tmp = claim;
  		break;
  	}
  	rcu_read_unlock();
  
  	return claim_tmp;
  }

  /**

   * batadv_backbone_hash_find() - looks for a backbone gateway in the hash

   * @bat_priv: the bat priv with all the soft interface information

   * @addr: the address of the originator
   * @vid: the VLAN ID
   *

   * Return: backbone gateway if found or NULL otherwise

   */

  static struct batadv_bla_backbone_gw *

  batadv_backbone_hash_find(struct batadv_priv *bat_priv, u8 *addr,
  			  unsigned short vid)

  {

  	struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;

  	struct hlist_head *head;

  	struct batadv_bla_backbone_gw search_entry, *backbone_gw;
  	struct batadv_bla_backbone_gw *backbone_gw_tmp = NULL;

  	int index;
  
  	if (!hash)
  		return NULL;

  	ether_addr_copy(search_entry.orig, addr);

  	search_entry.vid = vid;

  	index = batadv_choose_backbone_gw(&search_entry, hash->size);

  	head = &hash->table[index];
  
  	rcu_read_lock();

  	hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {

  		if (!batadv_compare_backbone_gw(&backbone_gw->hash_entry,
  						&search_entry))

  			continue;

  		if (!kref_get_unless_zero(&backbone_gw->refcount))

  			continue;
  
  		backbone_gw_tmp = backbone_gw;
  		break;
  	}
  	rcu_read_unlock();
  
  	return backbone_gw_tmp;
  }

  /**

   * batadv_bla_del_backbone_claims() - delete all claims for a backbone

   * @backbone_gw: backbone gateway where the claims should be removed
   */

  static void

  batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw)

  {

  	struct batadv_hashtable *hash;

  	struct hlist_node *node_tmp;

  	struct hlist_head *head;

  	struct batadv_bla_claim *claim;

  	int i;
  	spinlock_t *list_lock;	/* protects write access to the hash lists */

  	hash = backbone_gw->bat_priv->bla.claim_hash;

  	if (!hash)
  		return;
  
  	for (i = 0; i < hash->size; i++) {
  		head = &hash->table[i];
  		list_lock = &hash->list_locks[i];
  
  		spin_lock_bh(list_lock);

  		hlist_for_each_entry_safe(claim, node_tmp,

  					  head, hash_entry) {

  			if (claim->backbone_gw != backbone_gw)
  				continue;

  			batadv_claim_put(claim);

  			hlist_del_rcu(&claim->hash_entry);

  		}
  		spin_unlock_bh(list_lock);
  	}

  	/* all claims gone, initialize CRC */

  	spin_lock_bh(&backbone_gw->crc_lock);

  	backbone_gw->crc = BATADV_BLA_CRC_INIT;

  	spin_unlock_bh(&backbone_gw->crc_lock);

  }

  /**

   * batadv_bla_send_claim() - sends a claim frame according to the provided info

   * @bat_priv: the bat priv with all the soft interface information

   * @mac: the mac address to be announced within the claim

   * @vid: the VLAN ID
   * @claimtype: the type of the claim (CLAIM, UNCLAIM, ANNOUNCE, ...)

   */

  static void batadv_bla_send_claim(struct batadv_priv *bat_priv, u8 *mac,

  				  unsigned short vid, int claimtype)

  {
  	struct sk_buff *skb;
  	struct ethhdr *ethhdr;

  	struct batadv_hard_iface *primary_if;

  	struct net_device *soft_iface;

  	u8 *hw_src;

  	struct batadv_bla_claim_dst local_claim_dest;

  	__be32 zeroip = 0;

  	primary_if = batadv_primary_if_get_selected(bat_priv);

  	if (!primary_if)
  		return;

  	memcpy(&local_claim_dest, &bat_priv->bla.claim_dest,

  	       sizeof(local_claim_dest));

  	local_claim_dest.type = claimtype;
  
  	soft_iface = primary_if->soft_iface;
  
  	skb = arp_create(ARPOP_REPLY, ETH_P_ARP,
  			 /* IP DST: 0.0.0.0 */
  			 zeroip,
  			 primary_if->soft_iface,
  			 /* IP SRC: 0.0.0.0 */
  			 zeroip,
  			 /* Ethernet DST: Broadcast */
  			 NULL,
  			 /* Ethernet SRC/HW SRC:  originator mac */
  			 primary_if->net_dev->dev_addr,

  			 /* HW DST: FF:43:05:XX:YY:YY

  			  * with XX   = claim type

  			  * and YY:YY = group id

  			  */

  			 (u8 *)&local_claim_dest);

  
  	if (!skb)
  		goto out;
  
  	ethhdr = (struct ethhdr *)skb->data;

  	hw_src = (u8 *)ethhdr + ETH_HLEN + sizeof(struct arphdr);

  
  	/* now we pretend that the client would have sent this ... */
  	switch (claimtype) {

  	case BATADV_CLAIM_TYPE_CLAIM:

  		/* normal claim frame
  		 * set Ethernet SRC to the clients mac
  		 */

  		ether_addr_copy(ethhdr->h_source, mac);

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): CLAIM %pM on vid %d
  ", __func__, mac,

  			   batadv_print_vid(vid));

  		break;

  	case BATADV_CLAIM_TYPE_UNCLAIM:

  		/* unclaim frame
  		 * set HW SRC to the clients mac
  		 */

  		ether_addr_copy(hw_src, mac);

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): UNCLAIM %pM on vid %d
  ", __func__, mac,

  			   batadv_print_vid(vid));

  		break;

  	case BATADV_CLAIM_TYPE_ANNOUNCE:

  		/* announcement frame
  		 * set HW SRC to the special mac containg the crc
  		 */

  		ether_addr_copy(hw_src, mac);

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): ANNOUNCE of %pM on vid %d
  ", __func__,

  			   ethhdr->h_source, batadv_print_vid(vid));

  		break;

  	case BATADV_CLAIM_TYPE_REQUEST:

  		/* request frame

  		 * set HW SRC and header destination to the receiving backbone
  		 * gws mac

  		 */

  		ether_addr_copy(hw_src, mac);
  		ether_addr_copy(ethhdr->h_dest, mac);

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): REQUEST of %pM to %pM on vid %d
  ", __func__,

  			   ethhdr->h_source, ethhdr->h_dest,

  			   batadv_print_vid(vid));

  		break;

  	case BATADV_CLAIM_TYPE_LOOPDETECT:
  		ether_addr_copy(ethhdr->h_source, mac);
  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): LOOPDETECT of %pM to %pM on vid %d
  ",
  			   __func__, ethhdr->h_source, ethhdr->h_dest,

  			   batadv_print_vid(vid));

  
  		break;

  	}

  	if (vid & BATADV_VLAN_HAS_TAG) {

  		skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
  				      vid & VLAN_VID_MASK);

  		if (!skb)
  			goto out;
  	}

  
  	skb_reset_mac_header(skb);
  	skb->protocol = eth_type_trans(skb, soft_iface);

  	batadv_inc_counter(bat_priv, BATADV_CNT_RX);
  	batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
  			   skb->len + ETH_HLEN);

  	if (in_interrupt())
  		netif_rx(skb);
  	else
  		netif_rx_ni(skb);

  out:
  	if (primary_if)

  		batadv_hardif_put(primary_if);

  }

  /**

   * batadv_bla_loopdetect_report() - worker for reporting the loop

   * @work: work queue item
   *
   * Throws an uevent, as the loopdetect check function can't do that itself
   * since the kernel may sleep while throwing uevents.
   */
  static void batadv_bla_loopdetect_report(struct work_struct *work)
  {
  	struct batadv_bla_backbone_gw *backbone_gw;
  	struct batadv_priv *bat_priv;
  	char vid_str[6] = { '\0' };
  
  	backbone_gw = container_of(work, struct batadv_bla_backbone_gw,
  				   report_work);
  	bat_priv = backbone_gw->bat_priv;
  
  	batadv_info(bat_priv->soft_iface,
  		    "Possible loop on VLAN %d detected which can't be handled by BLA - please check your network setup!
  ",

  		    batadv_print_vid(backbone_gw->vid));

  	snprintf(vid_str, sizeof(vid_str), "%d",

  		 batadv_print_vid(backbone_gw->vid));

  	vid_str[sizeof(vid_str) - 1] = 0;
  
  	batadv_throw_uevent(bat_priv, BATADV_UEV_BLA, BATADV_UEV_LOOPDETECT,
  			    vid_str);
  
  	batadv_backbone_gw_put(backbone_gw);
  }
  
  /**

   * batadv_bla_get_backbone_gw() - finds or creates a backbone gateway

   * @bat_priv: the bat priv with all the soft interface information

   * @orig: the mac address of the originator
   * @vid: the VLAN ID

   * @own_backbone: set if the requested backbone is local

   *

   * Return: the (possibly created) backbone gateway or NULL on error

   */

  static struct batadv_bla_backbone_gw *

  batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, u8 *orig,

  			   unsigned short vid, bool own_backbone)

  {

  	struct batadv_bla_backbone_gw *entry;

  	struct batadv_orig_node *orig_node;

  	int hash_added;

  	entry = batadv_backbone_hash_find(bat_priv, orig, vid);

  
  	if (entry)
  		return entry;

  	batadv_dbg(BATADV_DBG_BLA, bat_priv,

  		   "%s(): not found (%pM, %d), creating new entry
  ", __func__,

  		   orig, batadv_print_vid(vid));

  
  	entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
  	if (!entry)
  		return NULL;
  
  	entry->vid = vid;
  	entry->lasttime = jiffies;

  	entry->crc = BATADV_BLA_CRC_INIT;

  	entry->bat_priv = bat_priv;

  	spin_lock_init(&entry->crc_lock);

  	atomic_set(&entry->request_sent, 0);

  	atomic_set(&entry->wait_periods, 0);

  	ether_addr_copy(entry->orig, orig);

  	INIT_WORK(&entry->report_work, batadv_bla_loopdetect_report);

  	kref_init(&entry->refcount);

  	kref_get(&entry->refcount);

  	hash_added = batadv_hash_add(bat_priv->bla.backbone_hash,

  				     batadv_compare_backbone_gw,
  				     batadv_choose_backbone_gw, entry,
  				     &entry->hash_entry);

  
  	if (unlikely(hash_added != 0)) {
  		/* hash failed, free the structure */
  		kfree(entry);
  		return NULL;
  	}

  	/* this is a gateway now, remove any TT entry on this VLAN */

  	orig_node = batadv_orig_hash_find(bat_priv, orig);

  	if (orig_node) {

  		batadv_tt_global_del_orig(bat_priv, orig_node, vid,

  					  "became a backbone gateway");

  		batadv_orig_node_put(orig_node);

  	}

  	if (own_backbone) {

  		batadv_bla_send_announce(bat_priv, entry);

  		/* this will be decreased in the worker thread */
  		atomic_inc(&entry->request_sent);

  		atomic_set(&entry->wait_periods, BATADV_BLA_WAIT_PERIODS);

  		atomic_inc(&bat_priv->bla.num_requests);
  	}

  	return entry;
  }

  /**

   * batadv_bla_update_own_backbone_gw() - updates the own backbone gw for a VLAN

   * @bat_priv: the bat priv with all the soft interface information
   * @primary_if: the selected primary interface
   * @vid: VLAN identifier
   *
   * update or add the own backbone gw to make sure we announce

   * where we receive other backbone gws
   */

  static void
  batadv_bla_update_own_backbone_gw(struct batadv_priv *bat_priv,
  				  struct batadv_hard_iface *primary_if,

  				  unsigned short vid)

  {

  	struct batadv_bla_backbone_gw *backbone_gw;

  	backbone_gw = batadv_bla_get_backbone_gw(bat_priv,
  						 primary_if->net_dev->dev_addr,

  						 vid, true);

  	if (unlikely(!backbone_gw))
  		return;
  
  	backbone_gw->lasttime = jiffies;

  	batadv_backbone_gw_put(backbone_gw);

  }

  /**

   * batadv_bla_answer_request() - answer a bla request by sending own claims

   * @bat_priv: the bat priv with all the soft interface information

   * @primary_if: interface where the request came on

   * @vid: the vid where the request came on
   *
   * Repeat all of our own claims, and finally send an ANNOUNCE frame
   * to allow the requester another check if the CRC is correct now.
   */

  static void batadv_bla_answer_request(struct batadv_priv *bat_priv,
  				      struct batadv_hard_iface *primary_if,

  				      unsigned short vid)

  {

  	struct hlist_head *head;

  	struct batadv_hashtable *hash;

  	struct batadv_bla_claim *claim;

  	struct batadv_bla_backbone_gw *backbone_gw;

  	int i;

  	batadv_dbg(BATADV_DBG_BLA, bat_priv,

  		   "%s(): received a claim request, send all of our own claims again
  ",
  		   __func__);

  	backbone_gw = batadv_backbone_hash_find(bat_priv,
  						primary_if->net_dev->dev_addr,
  						vid);

  	if (!backbone_gw)
  		return;

  	hash = bat_priv->bla.claim_hash;

  	for (i = 0; i < hash->size; i++) {
  		head = &hash->table[i];
  
  		rcu_read_lock();

  		hlist_for_each_entry_rcu(claim, head, hash_entry) {

  			/* only own claims are interesting */
  			if (claim->backbone_gw != backbone_gw)
  				continue;

  			batadv_bla_send_claim(bat_priv, claim->addr, claim->vid,

  					      BATADV_CLAIM_TYPE_CLAIM);

  		}
  		rcu_read_unlock();
  	}
  
  	/* finally, send an announcement frame */

  	batadv_bla_send_announce(bat_priv, backbone_gw);

  	batadv_backbone_gw_put(backbone_gw);

  }

  /**

   * batadv_bla_send_request() - send a request to repeat claims

   * @backbone_gw: the backbone gateway from whom we are out of sync

   *
   * When the crc is wrong, ask the backbone gateway for a full table update.
   * After the request, it will repeat all of his own claims and finally
   * send an announcement claim with which we can check again.
   */

  static void batadv_bla_send_request(struct batadv_bla_backbone_gw *backbone_gw)

  {
  	/* first, remove all old entries */

  	batadv_bla_del_backbone_claims(backbone_gw);

  	batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
  		   "Sending REQUEST to %pM
  ", backbone_gw->orig);

  
  	/* send request */

  	batadv_bla_send_claim(backbone_gw->bat_priv, backbone_gw->orig,

  			      backbone_gw->vid, BATADV_CLAIM_TYPE_REQUEST);

  
  	/* no local broadcasts should be sent or received, for now. */
  	if (!atomic_read(&backbone_gw->request_sent)) {

  		atomic_inc(&backbone_gw->bat_priv->bla.num_requests);

  		atomic_set(&backbone_gw->request_sent, 1);
  	}
  }

  /**

   * batadv_bla_send_announce() - Send an announcement frame

   * @bat_priv: the bat priv with all the soft interface information

   * @backbone_gw: our backbone gateway which should be announced

   */

  static void batadv_bla_send_announce(struct batadv_priv *bat_priv,

  				     struct batadv_bla_backbone_gw *backbone_gw)

  {

  	u8 mac[ETH_ALEN];

  	__be16 crc;

  	memcpy(mac, batadv_announce_mac, 4);

  	spin_lock_bh(&backbone_gw->crc_lock);

  	crc = htons(backbone_gw->crc);

  	spin_unlock_bh(&backbone_gw->crc_lock);

  	memcpy(&mac[4], &crc, 2);

  	batadv_bla_send_claim(bat_priv, mac, backbone_gw->vid,

  			      BATADV_CLAIM_TYPE_ANNOUNCE);

  }

  /**

   * batadv_bla_add_claim() - Adds a claim in the claim hash

   * @bat_priv: the bat priv with all the soft interface information

   * @mac: the mac address of the claim
   * @vid: the VLAN ID of the frame
   * @backbone_gw: the backbone gateway which claims it

   */

  static void batadv_bla_add_claim(struct batadv_priv *bat_priv,

  				 const u8 *mac, const unsigned short vid,

  				 struct batadv_bla_backbone_gw *backbone_gw)

  {

  	struct batadv_bla_backbone_gw *old_backbone_gw;

  	struct batadv_bla_claim *claim;
  	struct batadv_bla_claim search_claim;

  	bool remove_crc = false;

  	int hash_added;

  	ether_addr_copy(search_claim.addr, mac);

  	search_claim.vid = vid;

  	claim = batadv_claim_hash_find(bat_priv, &search_claim);

  
  	/* create a new claim entry if it does not exist yet. */
  	if (!claim) {
  		claim = kzalloc(sizeof(*claim), GFP_ATOMIC);
  		if (!claim)
  			return;

  		ether_addr_copy(claim->addr, mac);

  		spin_lock_init(&claim->backbone_lock);

  		claim->vid = vid;
  		claim->lasttime = jiffies;

  		kref_get(&backbone_gw->refcount);

  		claim->backbone_gw = backbone_gw;

  		kref_init(&claim->refcount);

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): adding new entry %pM, vid %d to hash ...
  ",
  			   __func__, mac, batadv_print_vid(vid));

  
  		kref_get(&claim->refcount);

  		hash_added = batadv_hash_add(bat_priv->bla.claim_hash,

  					     batadv_compare_claim,
  					     batadv_choose_claim, claim,
  					     &claim->hash_entry);

  
  		if (unlikely(hash_added != 0)) {
  			/* only local changes happened. */
  			kfree(claim);
  			return;
  		}
  	} else {
  		claim->lasttime = jiffies;
  		if (claim->backbone_gw == backbone_gw)
  			/* no need to register a new backbone */
  			goto claim_free_ref;

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "%s(): changing ownership for %pM, vid %d to gw %pM
  ",
  			   __func__, mac, batadv_print_vid(vid),
  			   backbone_gw->orig);

  		remove_crc = true;

  	}

  
  	/* replace backbone_gw atomically and adjust reference counters */
  	spin_lock_bh(&claim->backbone_lock);
  	old_backbone_gw = claim->backbone_gw;

  	kref_get(&backbone_gw->refcount);

  	claim->backbone_gw = backbone_gw;

  	spin_unlock_bh(&claim->backbone_lock);

  	if (remove_crc) {
  		/* remove claim address from old backbone_gw */
  		spin_lock_bh(&old_backbone_gw->crc_lock);
  		old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
  		spin_unlock_bh(&old_backbone_gw->crc_lock);
  	}

  	batadv_backbone_gw_put(old_backbone_gw);
  
  	/* add claim address to new backbone_gw */

  	spin_lock_bh(&backbone_gw->crc_lock);

  	backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);

  	spin_unlock_bh(&backbone_gw->crc_lock);

  	backbone_gw->lasttime = jiffies;
  
  claim_free_ref:

  	batadv_claim_put(claim);

  }

  /**

   * batadv_bla_claim_get_backbone_gw() - Get valid reference for backbone_gw of

   *  claim
   * @claim: claim whose backbone_gw should be returned
   *
   * Return: valid reference to claim::backbone_gw
   */
  static struct batadv_bla_backbone_gw *
  batadv_bla_claim_get_backbone_gw(struct batadv_bla_claim *claim)
  {
  	struct batadv_bla_backbone_gw *backbone_gw;
  
  	spin_lock_bh(&claim->backbone_lock);
  	backbone_gw = claim->backbone_gw;
  	kref_get(&backbone_gw->refcount);
  	spin_unlock_bh(&claim->backbone_lock);
  
  	return backbone_gw;
  }
  
  /**

   * batadv_bla_del_claim() - delete a claim from the claim hash

   * @bat_priv: the bat priv with all the soft interface information
   * @mac: mac address of the claim to be removed
   * @vid: VLAN id for the claim to be removed

   */

  static void batadv_bla_del_claim(struct batadv_priv *bat_priv,

  				 const u8 *mac, const unsigned short vid)

  {

  	struct batadv_bla_claim search_claim, *claim;

  	struct batadv_bla_claim *claim_removed_entry;
  	struct hlist_node *claim_removed_node;

  	ether_addr_copy(search_claim.addr, mac);

  	search_claim.vid = vid;

  	claim = batadv_claim_hash_find(bat_priv, &search_claim);

  	if (!claim)
  		return;

  	batadv_dbg(BATADV_DBG_BLA, bat_priv, "%s(): %pM, vid %d
  ", __func__,

  		   mac, batadv_print_vid(vid));

  	claim_removed_node = batadv_hash_remove(bat_priv->bla.claim_hash,
  						batadv_compare_claim,
  						batadv_choose_claim, claim);
  	if (!claim_removed_node)
  		goto free_claim;

  	/* reference from the hash is gone */
  	claim_removed_entry = hlist_entry(claim_removed_node,
  					  struct batadv_bla_claim, hash_entry);
  	batadv_claim_put(claim_removed_entry);
  
  free_claim:

  	/* don't need the reference from hash_find() anymore */

  	batadv_claim_put(claim);

  }

  /**

   * batadv_handle_announce() - check for ANNOUNCE frame

   * @bat_priv: the bat priv with all the soft interface information
   * @an_addr: announcement mac address (ARP Sender HW address)
   * @backbone_addr: originator address of the sender (Ethernet source MAC)
   * @vid: the VLAN ID of the frame

   *

   * Return: true if handled

   */

  static bool batadv_handle_announce(struct batadv_priv *bat_priv, u8 *an_addr,
  				   u8 *backbone_addr, unsigned short vid)

  {

  	struct batadv_bla_backbone_gw *backbone_gw;

  	u16 backbone_crc, crc;

  	if (memcmp(an_addr, batadv_announce_mac, 4) != 0)

  		return false;

  	backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
  						 false);

  
  	if (unlikely(!backbone_gw))

  		return true;

  	/* handle as ANNOUNCE frame */
  	backbone_gw->lasttime = jiffies;

  	crc = ntohs(*((__force __be16 *)(&an_addr[4])));

  	batadv_dbg(BATADV_DBG_BLA, bat_priv,

  		   "%s(): ANNOUNCE vid %d (sent by %pM)... CRC = %#.4x
  ",
  		   __func__, batadv_print_vid(vid), backbone_gw->orig, crc);

  	spin_lock_bh(&backbone_gw->crc_lock);
  	backbone_crc = backbone_gw->crc;
  	spin_unlock_bh(&backbone_gw->crc_lock);
  
  	if (backbone_crc != crc) {

  		batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,

  			   "%s(): CRC FAILED for %pM/%d (my = %#.4x, sent = %#.4x)
  ",
  			   __func__, backbone_gw->orig,

  			   batadv_print_vid(backbone_gw->vid),

  			   backbone_crc, crc);

  		batadv_bla_send_request(backbone_gw);

  	} else {
  		/* if we have sent a request and the crc was OK,
  		 * we can allow traffic again.
  		 */
  		if (atomic_read(&backbone_gw->request_sent)) {

  			atomic_dec(&backbone_gw->bat_priv->bla.num_requests);

  			atomic_set(&backbone_gw->request_sent, 0);
  		}
  	}

  	batadv_backbone_gw_put(backbone_gw);

  	return true;

  }

  /**

   * batadv_handle_request() - check for REQUEST frame

   * @bat_priv: the bat priv with all the soft interface information
   * @primary_if: the primary hard interface of this batman soft interface
   * @backbone_addr: backbone address to be requested (ARP sender HW MAC)
   * @ethhdr: ethernet header of a packet
   * @vid: the VLAN ID of the frame

   *

   * Return: true if handled

   */

  static bool batadv_handle_request(struct batadv_priv *bat_priv,
  				  struct batadv_hard_iface *primary_if,
  				  u8 *backbone_addr, struct ethhdr *ethhdr,
  				  unsigned short vid)

  {
  	/* check for REQUEST frame */

  	if (!batadv_compare_eth(backbone_addr, ethhdr->h_dest))

  		return false;

  
  	/* sanity check, this should not happen on a normal switch,
  	 * we ignore it in this case.
  	 */

  	if (!batadv_compare_eth(ethhdr->h_dest, primary_if->net_dev->dev_addr))

  		return true;

  	batadv_dbg(BATADV_DBG_BLA, bat_priv,

  		   "%s(): REQUEST vid %d (sent by %pM)...
  ",
  		   __func__, batadv_print_vid(vid), ethhdr->h_source);

  	batadv_bla_answer_request(bat_priv, primary_if, vid);

  	return true;

  }

  /**

   * batadv_handle_unclaim() - check for UNCLAIM frame

   * @bat_priv: the bat priv with all the soft interface information
   * @primary_if: the primary hard interface of this batman soft interface
   * @backbone_addr: originator address of the backbone (Ethernet source)
   * @claim_addr: Client to be unclaimed (ARP sender HW MAC)
   * @vid: the VLAN ID of the frame

   *

   * Return: true if handled

   */

  static bool batadv_handle_unclaim(struct batadv_priv *bat_priv,
  				  struct batadv_hard_iface *primary_if,
  				  u8 *backbone_addr, u8 *claim_addr,
  				  unsigned short vid)

  {

  	struct batadv_bla_backbone_gw *backbone_gw;

  
  	/* unclaim in any case if it is our own */

  	if (primary_if && batadv_compare_eth(backbone_addr,
  					     primary_if->net_dev->dev_addr))

  		batadv_bla_send_claim(bat_priv, claim_addr, vid,

  				      BATADV_CLAIM_TYPE_UNCLAIM);

  	backbone_gw = batadv_backbone_hash_find(bat_priv, backbone_addr, vid);

  
  	if (!backbone_gw)

  		return true;

  
  	/* this must be an UNCLAIM frame */

  	batadv_dbg(BATADV_DBG_BLA, bat_priv,

  		   "%s(): UNCLAIM %pM on vid %d (sent by %pM)...
  ", __func__,

  		   claim_addr, batadv_print_vid(vid), backbone_gw->orig);

  	batadv_bla_del_claim(bat_priv, claim_addr, vid);

  	batadv_backbone_gw_put(backbone_gw);

  	return true;

  }

  /**

   * batadv_handle_claim() - check for CLAIM frame

   * @bat_priv: the bat priv with all the soft interface information
   * @primary_if: the primary hard interface of this batman soft interface
   * @backbone_addr: originator address of the backbone (Ethernet Source)
   * @claim_addr: client mac address to be claimed (ARP sender HW MAC)
   * @vid: the VLAN ID of the frame

   *

   * Return: true if handled

   */

  static bool batadv_handle_claim(struct batadv_priv *bat_priv,
  				struct batadv_hard_iface *primary_if,
  				u8 *backbone_addr, u8 *claim_addr,
  				unsigned short vid)

  {

  	struct batadv_bla_backbone_gw *backbone_gw;

  
  	/* register the gateway if not yet available, and add the claim. */

  	backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
  						 false);

  
  	if (unlikely(!backbone_gw))

  		return true;

  
  	/* this must be a CLAIM frame */

  	batadv_bla_add_claim(bat_priv, claim_addr, vid, backbone_gw);

  	if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))

  		batadv_bla_send_claim(bat_priv, claim_addr, vid,

  				      BATADV_CLAIM_TYPE_CLAIM);

  
  	/* TODO: we could call something like tt_local_del() here. */

  	batadv_backbone_gw_put(backbone_gw);

  	return true;

  }

  /**

   * batadv_check_claim_group() - check for claim group membership

   * @bat_priv: the bat priv with all the soft interface information

   * @primary_if: the primary interface of this batman interface

   * @hw_src: the Hardware source in the ARP Header
   * @hw_dst: the Hardware destination in the ARP Header
   * @ethhdr: pointer to the Ethernet header of the claim frame
   *

   * checks if it is a claim packet and if it's on the same group.

   * This function also applies the group ID of the sender
   * if it is in the same mesh.
   *

   * Return:

   *	2  - if it is a claim packet and on the same group
   *	1  - if is a claim packet from another group
   *	0  - if it is not a claim packet
   */

  static int batadv_check_claim_group(struct batadv_priv *bat_priv,
  				    struct batadv_hard_iface *primary_if,

  				    u8 *hw_src, u8 *hw_dst,

  				    struct ethhdr *ethhdr)

  {

  	u8 *backbone_addr;

  	struct batadv_orig_node *orig_node;

  	struct batadv_bla_claim_dst *bla_dst, *bla_dst_own;

  	bla_dst = (struct batadv_bla_claim_dst *)hw_dst;

  	bla_dst_own = &bat_priv->bla.claim_dest;

  	/* if announcement packet, use the source,
  	 * otherwise assume it is in the hw_src
  	 */
  	switch (bla_dst->type) {

  	case BATADV_CLAIM_TYPE_CLAIM:

  		backbone_addr = hw_src;
  		break;

  	case BATADV_CLAIM_TYPE_REQUEST:
  	case BATADV_CLAIM_TYPE_ANNOUNCE:

  	case BATADV_CLAIM_TYPE_UNCLAIM:

  		backbone_addr = ethhdr->h_source;
  		break;
  	default:
  		return 0;
  	}
  
  	/* don't accept claim frames from ourselves */

  	if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))

  		return 0;
  
  	/* if its already the same group, it is fine. */
  	if (bla_dst->group == bla_dst_own->group)
  		return 2;
  
  	/* lets see if this originator is in our mesh */

  	orig_node = batadv_orig_hash_find(bat_priv, backbone_addr);

  
  	/* dont accept claims from gateways which are not in
  	 * the same mesh or group.
  	 */
  	if (!orig_node)
  		return 1;
  
  	/* if our mesh friends mac is bigger, use it for ourselves. */
  	if (ntohs(bla_dst->group) > ntohs(bla_dst_own->group)) {

  		batadv_dbg(BATADV_DBG_BLA, bat_priv,

  			   "taking other backbones claim group: %#.4x
  ",

  			   ntohs(bla_dst->group));

  		bla_dst_own->group = bla_dst->group;
  	}

  	batadv_orig_node_put(orig_node);

  
  	return 2;
  }

  /**

   * batadv_bla_process_claim() - Check if this is a claim frame, and process it

   * @bat_priv: the bat priv with all the soft interface information

   * @primary_if: the primary hard interface of this batman soft interface

   * @skb: the frame to be checked
   *

   * Return: true if it was a claim frame, otherwise return false to

   * tell the callee that it can use the frame on its own.
   */

  static bool batadv_bla_process_claim(struct batadv_priv *bat_priv,
  				     struct batadv_hard_iface *primary_if,
  				     struct sk_buff *skb)

  {

  	struct batadv_bla_claim_dst *bla_dst, *bla_dst_own;

  	u8 *hw_src, *hw_dst;

  	struct vlan_hdr *vhdr, vhdr_buf;

  	struct ethhdr *ethhdr;

  	struct arphdr *arphdr;

  	unsigned short vid;

  	int vlan_depth = 0;

  	__be16 proto;

  	int headlen;

  	int ret;

  	vid = batadv_get_vid(skb, 0);

  	ethhdr = eth_hdr(skb);

  	proto = ethhdr->h_proto;
  	headlen = ETH_HLEN;
  	if (vid & BATADV_VLAN_HAS_TAG) {

  		/* Traverse the VLAN/Ethertypes.
  		 *
  		 * At this point it is known that the first protocol is a VLAN
  		 * header, so start checking at the encapsulated protocol.
  		 *
  		 * The depth of the VLAN headers is recorded to drop BLA claim
  		 * frames encapsulated into multiple VLAN headers (QinQ).
  		 */
  		do {
  			vhdr = skb_header_pointer(skb, headlen, VLAN_HLEN,
  						  &vhdr_buf);
  			if (!vhdr)

  				return false;

  
  			proto = vhdr->h_vlan_encapsulated_proto;
  			headlen += VLAN_HLEN;
  			vlan_depth++;
  		} while (proto == htons(ETH_P_8021Q));

  	}

  	if (proto != htons(ETH_P_ARP))

  		return false; /* not a claim frame */

  
  	/* this must be a ARP frame. check if it is a claim. */
  
  	if (unlikely(!pskb_may_pull(skb, headlen + arp_hdr_len(skb->dev))))

  		return false;

  
  	/* pskb_may_pull() may have modified the pointers, get ethhdr again */

  	ethhdr = eth_hdr(skb);

  	arphdr = (struct arphdr *)((u8 *)ethhdr + headlen);

  
  	/* Check whether the ARP frame carries a valid
  	 * IP information
  	 */

  	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))

  		return false;

  	if (arphdr->ar_pro != htons(ETH_P_IP))

  		return false;

  	if (arphdr->ar_hln != ETH_ALEN)

  		return false;

  	if (arphdr->ar_pln != 4)

  		return false;

  	hw_src = (u8 *)arphdr + sizeof(struct arphdr);

  	hw_dst = hw_src + ETH_ALEN + 4;

  	bla_dst = (struct batadv_bla_claim_dst *)hw_dst;

  	bla_dst_own = &bat_priv->bla.claim_dest;
  
  	/* check if it is a claim frame in general */
  	if (memcmp(bla_dst->magic, bla_dst_own->magic,
  		   sizeof(bla_dst->magic)) != 0)

  		return false;

  
  	/* check if there is a claim frame encapsulated deeper in (QinQ) and
  	 * drop that, as this is not supported by BLA but should also not be
  	 * sent via the mesh.
  	 */
  	if (vlan_depth > 1)

  		return true;

  	/* Let the loopdetect frames on the mesh in any case. */
  	if (bla_dst->type == BATADV_CLAIM_TYPE_LOOPDETECT)