batman-adv: remove FSF address from GPL disclaimer

[deliverable/linux.git] / net / batman-adv / bridge_loop_avoidance.c

/* Copyright (C) 2011-2013 B.A.T.M.A.N. contributors:
 *
 * Simon Wunderlich
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "main.h"
#include "hash.h"
#include "hard-interface.h"
#include "originator.h"
#include "bridge_loop_avoidance.h"
#include "translation-table.h"
#include "send.h"

#include <linux/etherdevice.h>
#include <linux/crc16.h>
#include <linux/if_arp.h>
#include <net/arp.h>
#include <linux/if_vlan.h>

static const uint8_t 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);

/* return the index of the claim */
static inline uint32_t batadv_choose_claim(const void *data, uint32_t size)
{
        struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;
        uint32_t hash = 0;

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

        hash += (hash << 3);
        hash ^= (hash >> 11);
        hash += (hash << 15);

        return hash % size;
}

/* return the index of the backbone gateway */
static inline uint32_t batadv_choose_backbone_gw(const void *data,
                                                 uint32_t size)
{
        const struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;
        uint32_t hash = 0;

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

        hash += (hash << 3);
        hash ^= (hash >> 11);
        hash += (hash << 15);

        return hash % size;
}


/* compares address and vid of two backbone gws */
static int 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, *gw2 = data2;

        if (!batadv_compare_eth(gw1->orig, gw2->orig))
                return 0;

        if (gw1->vid != gw2->vid)
                return 0;

        return 1;
}

/* compares address and vid of two claims */
static int 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, *cl2 = data2;

        if (!batadv_compare_eth(cl1->addr, cl2->addr))
                return 0;

        if (cl1->vid != cl2->vid)
                return 0;

        return 1;
}

/* free a backbone gw */
static void
batadv_backbone_gw_free_ref(struct batadv_bla_backbone_gw *backbone_gw)
{
        if (atomic_dec_and_test(&backbone_gw->refcount))
                kfree_rcu(backbone_gw, rcu);
}

/* finally deinitialize the claim */
static void batadv_claim_free_rcu(struct rcu_head *rcu)
{
        struct batadv_bla_claim *claim;

        claim = container_of(rcu, struct batadv_bla_claim, rcu);

        batadv_backbone_gw_free_ref(claim->backbone_gw);
        kfree(claim);
}

/* free a claim, call claim_free_rcu if its the last reference */
static void batadv_claim_free_ref(struct batadv_bla_claim *claim)
{
        if (atomic_dec_and_test(&claim->refcount))
                call_rcu(&claim->rcu, batadv_claim_free_rcu);
}

/* @bat_priv: the bat priv with all the soft interface information
 * @data: search data (may be local/static data)
 *
 * looks for a claim in the hash, and returns it 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 (!atomic_inc_not_zero(&claim->refcount))
                        continue;

                claim_tmp = claim;
                break;
        }
        rcu_read_unlock();

        return claim_tmp;
}

/**
 * batadv_backbone_hash_find - looks for a claim in the hash
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: the address of the originator
 * @vid: the VLAN ID
 *
 * Returns claim if found or NULL otherwise.
 */
static struct batadv_bla_backbone_gw *
batadv_backbone_hash_find(struct batadv_priv *bat_priv,
                          uint8_t *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;

        memcpy(search_entry.orig, addr, ETH_ALEN);
        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 (!atomic_inc_not_zero(&backbone_gw->refcount))
                        continue;

                backbone_gw_tmp = backbone_gw;
                break;
        }
        rcu_read_unlock();

        return backbone_gw_tmp;
}

/* delete all claims for a backbone */
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_free_ref(claim);
                        hlist_del_rcu(&claim->hash_entry);
                }
                spin_unlock_bh(list_lock);
        }

        /* all claims gone, intialize CRC */
        backbone_gw->crc = BATADV_BLA_CRC_INIT;
}

/**
 * batadv_bla_send_claim - sends a claim frame according to the provided info
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: 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, uint8_t *mac,
                                  unsigned short vid, int claimtype)
{
        struct sk_buff *skb;
        struct ethhdr *ethhdr;
        struct batadv_hard_iface *primary_if;
        struct net_device *soft_iface;
        uint8_t *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
                          */
                         (uint8_t *)&local_claim_dest);

        if (!skb)
                goto out;

        ethhdr = (struct ethhdr *)skb->data;
        hw_src = (uint8_t *)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
                 */
                memcpy(ethhdr->h_source, mac, ETH_ALEN);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): CLAIM %pM on vid %d\n", mac,
                           BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_UNCLAIM:
                /* unclaim frame
                 * set HW SRC to the clients mac
                 */
                memcpy(hw_src, mac, ETH_ALEN);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): UNCLAIM %pM on vid %d\n", mac,
                           BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_ANNOUNCE:
                /* announcement frame
                 * set HW SRC to the special mac containg the crc
                 */
                memcpy(hw_src, mac, ETH_ALEN);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): ANNOUNCE of %pM on vid %d\n",
                           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
                 */
                memcpy(hw_src, mac, ETH_ALEN);
                memcpy(ethhdr->h_dest, mac, ETH_ALEN);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): REQUEST of %pM to %pM on vid %d\n",
                           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);

        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);
        soft_iface->last_rx = jiffies;

        netif_rx(skb);
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

/**
 * batadv_bla_get_backbone_gw
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the mac address of the originator
 * @vid: the VLAN ID
 *
 * searches for the backbone gw or creates a new one if it could not
 * be found.
 */
static struct batadv_bla_backbone_gw *
batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, uint8_t *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,
                   "bla_get_backbone_gw(): not found (%pM, %d), creating new entry\n",
                   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;
        atomic_set(&entry->request_sent, 0);
        atomic_set(&entry->wait_periods, 0);
        memcpy(entry->orig, orig, ETH_ALEN);

        /* one for the hash, one for returning */
        atomic_set(&entry->refcount, 2);

        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_free_ref(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;
}

/* 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_free_ref(backbone_gw);
}

/* @bat_priv: the bat priv with all the soft interface information
 * @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,
                   "bla_answer_request(): received a claim request, send all of our own claims again\n");

        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_free_ref(backbone_gw);
}

/* @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\n", 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);
        }
}

/* @bat_priv: the bat priv with all the soft interface information
 * @backbone_gw: our backbone gateway which should be announced
 *
 * This function sends an announcement. It is called from multiple
 * places.
 */
static void batadv_bla_send_announce(struct batadv_priv *bat_priv,
                                     struct batadv_bla_backbone_gw *backbone_gw)
{
        uint8_t mac[ETH_ALEN];
        __be16 crc;

        memcpy(mac, batadv_announce_mac, 4);
        crc = htons(backbone_gw->crc);
        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 uint8_t *mac, const unsigned short vid,
                                 struct batadv_bla_backbone_gw *backbone_gw)
{
        struct batadv_bla_claim *claim;
        struct batadv_bla_claim search_claim;
        int hash_added;

        memcpy(search_claim.addr, mac, ETH_ALEN);
        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;

                memcpy(claim->addr, mac, ETH_ALEN);
                claim->vid = vid;
                claim->lasttime = jiffies;
                claim->backbone_gw = backbone_gw;

                atomic_set(&claim->refcount, 2);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_add_claim(): adding new entry %pM, vid %d to hash ...\n",
                           mac, BATADV_PRINT_VID(vid));
                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,
                           "bla_add_claim(): changing ownership for %pM, vid %d\n",
                           mac, BATADV_PRINT_VID(vid));

                claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
                batadv_backbone_gw_free_ref(claim->backbone_gw);
        }
        /* set (new) backbone gw */
        atomic_inc(&backbone_gw->refcount);
        claim->backbone_gw = backbone_gw;

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

claim_free_ref:
        batadv_claim_free_ref(claim);
}

/* Delete a claim from the claim hash which has the
 * given mac address and vid.
 */
static void batadv_bla_del_claim(struct batadv_priv *bat_priv,
                                 const uint8_t *mac, const unsigned short vid)
{
        struct batadv_bla_claim search_claim, *claim;

        memcpy(search_claim.addr, mac, ETH_ALEN);
        search_claim.vid = vid;
        claim = batadv_claim_hash_find(bat_priv, &search_claim);
        if (!claim)
                return;

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_del_claim(): %pM, vid %d\n",
                   mac, BATADV_PRINT_VID(vid));

        batadv_hash_remove(bat_priv->bla.claim_hash, batadv_compare_claim,
                           batadv_choose_claim, claim);
        batadv_claim_free_ref(claim); /* reference from the hash is gone */

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

        /* don't need the reference from hash_find() anymore */
        batadv_claim_free_ref(claim);
}

/* check for ANNOUNCE frame, return 1 if handled */
static int batadv_handle_announce(struct batadv_priv *bat_priv,
                                  uint8_t *an_addr, uint8_t *backbone_addr,
                                  unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        uint16_t crc;

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

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

        if (unlikely(!backbone_gw))
                return 1;


        /* handle as ANNOUNCE frame */
        backbone_gw->lasttime = jiffies;
        crc = ntohs(*((__be16 *)(&an_addr[4])));

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_announce(): ANNOUNCE vid %d (sent by %pM)... CRC = %#.4x\n",
                   BATADV_PRINT_VID(vid), backbone_gw->orig, crc);

        if (backbone_gw->crc != crc) {
                batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
                           "handle_announce(): CRC FAILED for %pM/%d (my = %#.4x, sent = %#.4x)\n",
                           backbone_gw->orig,
                           BATADV_PRINT_VID(backbone_gw->vid),
                           backbone_gw->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_free_ref(backbone_gw);
        return 1;
}

/* check for REQUEST frame, return 1 if handled */
static int batadv_handle_request(struct batadv_priv *bat_priv,
                                 struct batadv_hard_iface *primary_if,
                                 uint8_t *backbone_addr,
                                 struct ethhdr *ethhdr, unsigned short vid)
{
        /* check for REQUEST frame */
        if (!batadv_compare_eth(backbone_addr, ethhdr->h_dest))
                return 0;

        /* 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 1;

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_request(): REQUEST vid %d (sent by %pM)...\n",
                   BATADV_PRINT_VID(vid), ethhdr->h_source);

        batadv_bla_answer_request(bat_priv, primary_if, vid);
        return 1;
}

/* check for UNCLAIM frame, return 1 if handled */
static int batadv_handle_unclaim(struct batadv_priv *bat_priv,
                                 struct batadv_hard_iface *primary_if,
                                 uint8_t *backbone_addr,
                                 uint8_t *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 1;

        /* this must be an UNCLAIM frame */
        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_unclaim(): UNCLAIM %pM on vid %d (sent by %pM)...\n",
                   claim_addr, BATADV_PRINT_VID(vid), backbone_gw->orig);

        batadv_bla_del_claim(bat_priv, claim_addr, vid);
        batadv_backbone_gw_free_ref(backbone_gw);
        return 1;
}

/* check for CLAIM frame, return 1 if handled */
static int batadv_handle_claim(struct batadv_priv *bat_priv,
                               struct batadv_hard_iface *primary_if,
                               uint8_t *backbone_addr, uint8_t *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 1;

        /* 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_free_ref(backbone_gw);
        return 1;
}

/**
 * batadv_check_claim_group
 * @bat_priv: the bat priv with all the soft interface information
 * @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 its on the same group.
 * This function also applies the group ID of the sender
 * if it is in the same mesh.
 *
 * returns:
 *      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,
                                    uint8_t *hw_src, uint8_t *hw_dst,
                                    struct ethhdr *ethhdr)
{
        uint8_t *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;

        /* check if it is a claim packet in general */
        if (memcmp(bla_dst->magic, bla_dst_own->magic,
                   sizeof(bla_dst->magic)) != 0)
                return 0;

        /* 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\n",
                           ntohs(bla_dst->group));
                bla_dst_own->group = bla_dst->group;
        }

        batadv_orig_node_free_ref(orig_node);

        return 2;
}


/* @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 *
 * Check if this is a claim frame, and process it accordingly.
 *
 * returns 1 if it was a claim frame, otherwise return 0 to
 * tell the callee that it can use the frame on its own.
 */
static int 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;
        uint8_t *hw_src, *hw_dst;
        struct vlan_ethhdr *vhdr;
        struct ethhdr *ethhdr;
        struct arphdr *arphdr;
        unsigned short vid;
        __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) {
                vhdr = (struct vlan_ethhdr *)ethhdr;
                proto = vhdr->h_vlan_encapsulated_proto;
                headlen += VLAN_HLEN;
        }

        if (proto != htons(ETH_P_ARP))
                return 0; /* 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 0;

        /* pskb_may_pull() may have modified the pointers, get ethhdr again */
        ethhdr = eth_hdr(skb);
        arphdr = (struct arphdr *)((uint8_t *)ethhdr + headlen);

        /* Check whether the ARP frame carries a valid
         * IP information
         */
        if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
                return 0;
        if (arphdr->ar_pro != htons(ETH_P_IP))
                return 0;
        if (arphdr->ar_hln != ETH_ALEN)
                return 0;
        if (arphdr->ar_pln != 4)
                return 0;

        hw_src = (uint8_t *)arphdr + sizeof(struct arphdr);
        hw_dst = hw_src + ETH_ALEN + 4;
        bla_dst = (struct batadv_bla_claim_dst *)hw_dst;

        /* check if it is a claim frame. */
        ret = batadv_check_claim_group(bat_priv, primary_if, hw_src, hw_dst,
                                       ethhdr);
        if (ret == 1)
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_process_claim(): received a claim frame from another group. From: %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
                           ethhdr->h_source, BATADV_PRINT_VID(vid), hw_src,
                           hw_dst);

        if (ret < 2)
                return ret;

        /* become a backbone gw ourselves on this vlan if not happened yet */
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);

        /* check for the different types of claim frames ... */
        switch (bla_dst->type) {
        case BATADV_CLAIM_TYPE_CLAIM:
                if (batadv_handle_claim(bat_priv, primary_if, hw_src,
                                        ethhdr->h_source, vid))
                        return 1;
                break;
        case BATADV_CLAIM_TYPE_UNCLAIM:
                if (batadv_handle_unclaim(bat_priv, primary_if,
                                          ethhdr->h_source, hw_src, vid))
                        return 1;
                break;

        case BATADV_CLAIM_TYPE_ANNOUNCE:
                if (batadv_handle_announce(bat_priv, hw_src, ethhdr->h_source,
                                           vid))
                        return 1;
                break;
        case BATADV_CLAIM_TYPE_REQUEST:
                if (batadv_handle_request(bat_priv, primary_if, hw_src, ethhdr,
                                          vid))
                        return 1;
                break;
        }

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "bla_process_claim(): ERROR - this looks like a claim frame, but is useless. eth src %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
                   ethhdr->h_source, BATADV_PRINT_VID(vid), hw_src, hw_dst);
        return 1;
}

/* Check when we last heard from other nodes, and remove them in case of
 * a time out, or clean all backbone gws if now is set.
 */
static void batadv_bla_purge_backbone_gw(struct batadv_priv *bat_priv, int now)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        spinlock_t *list_lock;  /* protects write access to the hash lists */
        int i;

        hash = bat_priv->bla.backbone_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(backbone_gw, node_tmp,
                                          head, hash_entry) {
                        if (now)
                                goto purge_now;
                        if (!batadv_has_timed_out(backbone_gw->lasttime,
                                                  BATADV_BLA_BACKBONE_TIMEOUT))
                                continue;

                        batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
                                   "bla_purge_backbone_gw(): backbone gw %pM timed out\n",
                                   backbone_gw->orig);

purge_now:
                        /* don't wait for the pending request anymore */
                        if (atomic_read(&backbone_gw->request_sent))
                                atomic_dec(&bat_priv->bla.num_requests);

                        batadv_bla_del_backbone_claims(backbone_gw);

                        hlist_del_rcu(&backbone_gw->hash_entry);
                        batadv_backbone_gw_free_ref(backbone_gw);
                }
                spin_unlock_bh(list_lock);
        }
}

/**
 * batadv_bla_purge_claims
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the selected primary interface, may be NULL if now is set
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we heard last time from our own claims, and remove them in case of
 * a time out, or clean all claims if now is set
 */
static void batadv_bla_purge_claims(struct batadv_priv *bat_priv,
                                    struct batadv_hard_iface *primary_if,
                                    int now)
{
        struct batadv_bla_claim *claim;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        int i;

        hash = bat_priv->bla.claim_hash;
        if (!hash)
                return;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(claim, head, hash_entry) {
                        if (now)
                                goto purge_now;
                        if (!batadv_compare_eth(claim->backbone_gw->orig,
                                                primary_if->net_dev->dev_addr))
                                continue;
                        if (!batadv_has_timed_out(claim->lasttime,
                                                  BATADV_BLA_CLAIM_TIMEOUT))
                                continue;

                        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                                   "bla_purge_claims(): %pM, vid %d, time out\n",
                                   claim->addr, claim->vid);

purge_now:
                        batadv_handle_unclaim(bat_priv, primary_if,
                                              claim->backbone_gw->orig,
                                              claim->addr, claim->vid);
                }
                rcu_read_unlock();
        }
}

/**
 * batadv_bla_update_orig_address
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the new selected primary_if
 * @oldif: the old primary interface, may be NULL
 *
 * Update the backbone gateways when the own orig address changes.
 */
void batadv_bla_update_orig_address(struct batadv_priv *bat_priv,
                                    struct batadv_hard_iface *primary_if,
                                    struct batadv_hard_iface *oldif)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        __be16 group;
        int i;

        /* reset bridge loop avoidance group id */
        group = htons(crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN));
        bat_priv->bla.claim_dest.group = group;

        /* purge everything when bridge loop avoidance is turned off */
        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                oldif = NULL;

        if (!oldif) {
                batadv_bla_purge_claims(bat_priv, NULL, 1);
                batadv_bla_purge_backbone_gw(bat_priv, 1);
                return;
        }

        hash = bat_priv->bla.backbone_hash;
        if (!hash)
                return;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        /* own orig still holds the old value. */
                        if (!batadv_compare_eth(backbone_gw->orig,
                                                oldif->net_dev->dev_addr))
                                continue;

                        memcpy(backbone_gw->orig,
                               primary_if->net_dev->dev_addr, ETH_ALEN);
                        /* send an announce frame so others will ask for our
                         * claims and update their tables.
                         */
                        batadv_bla_send_announce(bat_priv, backbone_gw);
                }
                rcu_read_unlock();
        }
}

/* periodic work to do:
 *  * purge structures when they are too old
 *  * send announcements
 */
static void batadv_bla_periodic_work(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_priv *bat_priv;
        struct batadv_priv_bla *priv_bla;
        struct hlist_head *head;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_hashtable *hash;
        struct batadv_hard_iface *primary_if;
        int i;

        delayed_work = container_of(work, struct delayed_work, work);
        priv_bla = container_of(delayed_work, struct batadv_priv_bla, work);
        bat_priv = container_of(priv_bla, struct batadv_priv, bla);
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;

        batadv_bla_purge_claims(bat_priv, primary_if, 0);
        batadv_bla_purge_backbone_gw(bat_priv, 0);

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto out;

        hash = bat_priv->bla.backbone_hash;
        if (!hash)
                goto out;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        if (!batadv_compare_eth(backbone_gw->orig,
                                                primary_if->net_dev->dev_addr))
                                continue;

                        backbone_gw->lasttime = jiffies;

                        batadv_bla_send_announce(bat_priv, backbone_gw);

                        /* request_sent is only set after creation to avoid
                         * problems when we are not yet known as backbone gw
                         * in the backbone.
                         *
                         * We can reset this now after we waited some periods
                         * to give bridge forward delays and bla group forming
                         * some grace time.
                         */

                        if (atomic_read(&backbone_gw->request_sent) == 0)
                                continue;

                        if (!atomic_dec_and_test(&backbone_gw->wait_periods))
                                continue;

                        atomic_dec(&backbone_gw->bat_priv->bla.num_requests);
                        atomic_set(&backbone_gw->request_sent, 0);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
                           msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
}

/* The hash for claim and backbone hash receive the same key because they
 * are getting initialized by hash_new with the same key. Reinitializing
 * them with to different keys to allow nested locking without generating
 * lockdep warnings
 */
static struct lock_class_key batadv_claim_hash_lock_class_key;
static struct lock_class_key batadv_backbone_hash_lock_class_key;

/* initialize all bla structures */
int batadv_bla_init(struct batadv_priv *bat_priv)
{
        int i;
        uint8_t claim_dest[ETH_ALEN] = {0xff, 0x43, 0x05, 0x00, 0x00, 0x00};
        struct batadv_hard_iface *primary_if;
        uint16_t crc;
        unsigned long entrytime;

        spin_lock_init(&bat_priv->bla.bcast_duplist_lock);

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hash registering\n");

        /* setting claim destination address */
        memcpy(&bat_priv->bla.claim_dest.magic, claim_dest, 3);
        bat_priv->bla.claim_dest.type = 0;
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (primary_if) {
                crc = crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN);
                bat_priv->bla.claim_dest.group = htons(crc);
                batadv_hardif_free_ref(primary_if);
        } else {
                bat_priv->bla.claim_dest.group = 0; /* will be set later */
        }

        /* initialize the duplicate list */
        entrytime = jiffies - msecs_to_jiffies(BATADV_DUPLIST_TIMEOUT);
        for (i = 0; i < BATADV_DUPLIST_SIZE; i++)
                bat_priv->bla.bcast_duplist[i].entrytime = entrytime;
        bat_priv->bla.bcast_duplist_curr = 0;

        if (bat_priv->bla.claim_hash)
                return 0;

        bat_priv->bla.claim_hash = batadv_hash_new(128);
        bat_priv->bla.backbone_hash = batadv_hash_new(32);

        if (!bat_priv->bla.claim_hash || !bat_priv->bla.backbone_hash)
                return -ENOMEM;

        batadv_hash_set_lock_class(bat_priv->bla.claim_hash,
                                   &batadv_claim_hash_lock_class_key);
        batadv_hash_set_lock_class(bat_priv->bla.backbone_hash,
                                   &batadv_backbone_hash_lock_class_key);

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hashes initialized\n");

        INIT_DELAYED_WORK(&bat_priv->bla.work, batadv_bla_periodic_work);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
                           msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
        return 0;
}

/**
 * batadv_bla_check_bcast_duplist
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: contains the bcast_packet to be checked
 *
 * check if it is on our broadcast list. Another gateway might
 * have sent the same packet because it is connected to the same backbone,
 * so we have to remove this duplicate.
 *
 * This is performed by checking the CRC, which will tell us
 * with a good chance that it is the same packet. If it is furthermore
 * sent by another host, drop it. We allow equal packets from
 * the same host however as this might be intended.
 */
int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
                                   struct sk_buff *skb)
{
        int i, curr, ret = 0;
        __be32 crc;
        struct batadv_bcast_packet *bcast_packet;
        struct batadv_bcast_duplist_entry *entry;

        bcast_packet = (struct batadv_bcast_packet *)skb->data;

        /* calculate the crc ... */
        crc = batadv_skb_crc32(skb, (u8 *)(bcast_packet + 1));

        spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);

        for (i = 0; i < BATADV_DUPLIST_SIZE; i++) {
                curr = (bat_priv->bla.bcast_duplist_curr + i);
                curr %= BATADV_DUPLIST_SIZE;
                entry = &bat_priv->bla.bcast_duplist[curr];

                /* we can stop searching if the entry is too old ;
                 * later entries will be even older
                 */
                if (batadv_has_timed_out(entry->entrytime,
                                         BATADV_DUPLIST_TIMEOUT))
                        break;

                if (entry->crc != crc)
                        continue;

                if (batadv_compare_eth(entry->orig, bcast_packet->orig))
                        continue;

                /* this entry seems to match: same crc, not too old,
                 * and from another gw. therefore return 1 to forbid it.
                 */
                ret = 1;
                goto out;
        }
        /* not found, add a new entry (overwrite the oldest entry)
         * and allow it, its the first occurence.
         */
        curr = (bat_priv->bla.bcast_duplist_curr + BATADV_DUPLIST_SIZE - 1);
        curr %= BATADV_DUPLIST_SIZE;
        entry = &bat_priv->bla.bcast_duplist[curr];
        entry->crc = crc;
        entry->entrytime = jiffies;
        memcpy(entry->orig, bcast_packet->orig, ETH_ALEN);
        bat_priv->bla.bcast_duplist_curr = curr;

out:
        spin_unlock_bh(&bat_priv->bla.bcast_duplist_lock);

        return ret;
}



/* @bat_priv: the bat priv with all the soft interface information
 * @orig: originator mac address
 * @vid: VLAN identifier
 *
 * Check if the originator is a gateway for the VLAN identified by vid.
 *
 * Returns true if orig is a backbone for this vid, false otherwise.
 */
bool batadv_bla_is_backbone_gw_orig(struct batadv_priv *bat_priv, uint8_t *orig,
                                    unsigned short vid)
{
        struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
        struct hlist_head *head;
        struct batadv_bla_backbone_gw *backbone_gw;
        int i;

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                return false;

        if (!hash)
                return false;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        if (batadv_compare_eth(backbone_gw->orig, orig) &&
                            backbone_gw->vid == vid) {
                                rcu_read_unlock();
                                return true;
                        }
                }
                rcu_read_unlock();
        }

        return false;
}


/**
 * batadv_bla_is_backbone_gw
 * @skb: the frame to be checked
 * @orig_node: the orig_node of the frame
 * @hdr_size: maximum length of the frame
 *
 * bla_is_backbone_gw inspects the skb for the VLAN ID and returns 1
 * if the orig_node is also a gateway on the soft interface, otherwise it
 * returns 0.
 */
int batadv_bla_is_backbone_gw(struct sk_buff *skb,
                              struct batadv_orig_node *orig_node, int hdr_size)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        unsigned short vid;

        if (!atomic_read(&orig_node->bat_priv->bridge_loop_avoidance))
                return 0;

        /* first, find out the vid. */
        if (!pskb_may_pull(skb, hdr_size + ETH_HLEN))
                return 0;

        vid = batadv_get_vid(skb, hdr_size);

        /* see if this originator is a backbone gw for this VLAN */
        backbone_gw = batadv_backbone_hash_find(orig_node->bat_priv,
                                                orig_node->orig, vid);
        if (!backbone_gw)
                return 0;

        batadv_backbone_gw_free_ref(backbone_gw);
        return 1;
}

/* free all bla structures (for softinterface free or module unload) */
void batadv_bla_free(struct batadv_priv *bat_priv)
{
        struct batadv_hard_iface *primary_if;

        cancel_delayed_work_sync(&bat_priv->bla.work);
        primary_if = batadv_primary_if_get_selected(bat_priv);

        if (bat_priv->bla.claim_hash) {
                batadv_bla_purge_claims(bat_priv, primary_if, 1);
                batadv_hash_destroy(bat_priv->bla.claim_hash);
                bat_priv->bla.claim_hash = NULL;
        }
        if (bat_priv->bla.backbone_hash) {
                batadv_bla_purge_backbone_gw(bat_priv, 1);
                batadv_hash_destroy(bat_priv->bla.backbone_hash);
                bat_priv->bla.backbone_hash = NULL;
        }
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

/**
 * batadv_bla_rx
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 * @is_bcast: the packet came in a broadcast packet type.
 *
 * bla_rx avoidance checks if:
 *  * we have to race for a claim
 *  * if the frame is allowed on the LAN
 *
 * in these cases, the skb is further handled by this function and
 * returns 1, otherwise it returns 0 and the caller shall further
 * process the skb.
 */
int batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
                  unsigned short vid, bool is_bcast)
{
        struct ethhdr *ethhdr;
        struct batadv_bla_claim search_claim, *claim = NULL;
        struct batadv_hard_iface *primary_if;
        int ret;

        ethhdr = eth_hdr(skb);

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto handled;

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto allow;


        if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
                /* don't allow broadcasts while requests are in flight */
                if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast)
                        goto handled;

        memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
        search_claim.vid = vid;
        claim = batadv_claim_hash_find(bat_priv, &search_claim);

        if (!claim) {
                /* possible optimization: race for a claim */
                /* No claim exists yet, claim it for us!
                 */
                batadv_handle_claim(bat_priv, primary_if,
                                    primary_if->net_dev->dev_addr,
                                    ethhdr->h_source, vid);
                goto allow;
        }

        /* if it is our own claim ... */
        if (batadv_compare_eth(claim->backbone_gw->orig,
                               primary_if->net_dev->dev_addr)) {
                /* ... allow it in any case */
                claim->lasttime = jiffies;
                goto allow;
        }

        /* if it is a broadcast ... */
        if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast) {
                /* ... drop it. the responsible gateway is in charge.
                 *
                 * We need to check is_bcast because with the gateway
                 * feature, broadcasts (like DHCP requests) may be sent
                 * using a unicast packet type.
                 */
                goto handled;
        } else {
                /* seems the client considers us as its best gateway.
                 * send a claim and update the claim table
                 * immediately.
                 */
                batadv_handle_claim(bat_priv, primary_if,
                                    primary_if->net_dev->dev_addr,
                                    ethhdr->h_source, vid);
                goto allow;
        }
allow:
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
        ret = 0;
        goto out;

handled:
        kfree_skb(skb);
        ret = 1;

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        if (claim)
                batadv_claim_free_ref(claim);
        return ret;
}

/**
 * batadv_bla_tx
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 *
 * bla_tx checks if:
 *  * a claim was received which has to be processed
 *  * the frame is allowed on the mesh
 *
 * in these cases, the skb is further handled by this function and
 * returns 1, otherwise it returns 0 and the caller shall further
 * process the skb.
 *
 * This call might reallocate skb data.
 */
int batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
                  unsigned short vid)
{
        struct ethhdr *ethhdr;
        struct batadv_bla_claim search_claim, *claim = NULL;
        struct batadv_hard_iface *primary_if;
        int ret = 0;

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto allow;

        /* in VLAN case, the mac header might not be set. */
        skb_reset_mac_header(skb);

        if (batadv_bla_process_claim(bat_priv, primary_if, skb))
                goto handled;

        ethhdr = eth_hdr(skb);

        if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
                /* don't allow broadcasts while requests are in flight */
                if (is_multicast_ether_addr(ethhdr->h_dest))
                        goto handled;

        memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
        search_claim.vid = vid;

        claim = batadv_claim_hash_find(bat_priv, &search_claim);

        /* if no claim exists, allow it. */
        if (!claim)
                goto allow;

        /* check if we are responsible. */
        if (batadv_compare_eth(claim->backbone_gw->orig,
                               primary_if->net_dev->dev_addr)) {
                /* if yes, the client has roamed and we have
                 * to unclaim it.
                 */
                batadv_handle_unclaim(bat_priv, primary_if,
                                      primary_if->net_dev->dev_addr,
                                      ethhdr->h_source, vid);
                goto allow;
        }

        /* check if it is a multicast/broadcast frame */
        if (is_multicast_ether_addr(ethhdr->h_dest)) {
                /* drop it. the responsible gateway has forwarded it into
                 * the backbone network.
                 */
                goto handled;
        } else {
                /* we must allow it. at least if we are
                 * responsible for the DESTINATION.
                 */
                goto allow;
        }
allow:
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
        ret = 0;
        goto out;
handled:
        ret = 1;
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        if (claim)
                batadv_claim_free_ref(claim);
        return ret;
}

int batadv_bla_claim_table_seq_print_text(struct seq_file *seq, void *offset)
{
        struct net_device *net_dev = (struct net_device *)seq->private;
        struct batadv_priv *bat_priv = netdev_priv(net_dev);
        struct batadv_hashtable *hash = bat_priv->bla.claim_hash;
        struct batadv_bla_claim *claim;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        uint32_t i;
        bool is_own;
        uint8_t *primary_addr;

        primary_if = batadv_seq_print_text_primary_if_get(seq);
        if (!primary_if)
                goto out;

        primary_addr = primary_if->net_dev->dev_addr;
        seq_printf(seq,
                   "Claims announced for the mesh %s (orig %pM, group id %#.4x)\n",
                   net_dev->name, primary_addr,
                   ntohs(bat_priv->bla.claim_dest.group));
        seq_printf(seq, "   %-17s    %-5s    %-17s [o] (%-6s)\n",
                   "Client", "VID", "Originator", "CRC");
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(claim, head, hash_entry) {
                        is_own = batadv_compare_eth(claim->backbone_gw->orig,
                                                    primary_addr);
                        seq_printf(seq, " * %pM on %5d by %pM [%c] (%#.4x)\n",
                                   claim->addr, BATADV_PRINT_VID(claim->vid),
                                   claim->backbone_gw->orig,
                                   (is_own ? 'x' : ' '),
                                   claim->backbone_gw->crc);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return 0;
}

int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq, void *offset)
{
        struct net_device *net_dev = (struct net_device *)seq->private;
        struct batadv_priv *bat_priv = netdev_priv(net_dev);
        struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        int secs, msecs;
        uint32_t i;
        bool is_own;
        uint8_t *primary_addr;

        primary_if = batadv_seq_print_text_primary_if_get(seq);
        if (!primary_if)
                goto out;

        primary_addr = primary_if->net_dev->dev_addr;
        seq_printf(seq,
                   "Backbones announced for the mesh %s (orig %pM, group id %#.4x)\n",
                   net_dev->name, primary_addr,
                   ntohs(bat_priv->bla.claim_dest.group));
        seq_printf(seq, "   %-17s    %-5s %-9s (%-6s)\n",
                   "Originator", "VID", "last seen", "CRC");
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        msecs = jiffies_to_msecs(jiffies -
                                                 backbone_gw->lasttime);
                        secs = msecs / 1000;
                        msecs = msecs % 1000;

                        is_own = batadv_compare_eth(backbone_gw->orig,
                                                    primary_addr);
                        if (is_own)
                                continue;

                        seq_printf(seq, " * %pM on %5d %4i.%03is (%#.4x)\n",
                                   backbone_gw->orig,
                                   BATADV_PRINT_VID(backbone_gw->vid), secs,
                                   msecs, backbone_gw->crc);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return 0;
}