translation-table.c

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/* Copyright (C) 2007-2012 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich, Antonio Quartulli
 *
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

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

#include <linux/crc16.h>

static void batadv_send_roam_adv(struct batadv_priv *bat_priv, uint8_t *client,
                 struct batadv_orig_node *orig_node);
static void batadv_tt_purge(struct work_struct *work);
static void
batadv_tt_global_del_orig_list(struct batadv_tt_global_entry *tt_global_entry);
static void batadv_tt_global_del(struct batadv_priv *bat_priv,
                 struct batadv_orig_node *orig_node,
                 const unsigned char *addr,
                 const char *message, bool roaming);

/* returns 1 if they are the same mac addr */
static int batadv_compare_tt(const struct hlist_node *node, const void *data2)
{
    const void *data1 = container_of(node, struct batadv_tt_common_entry,
                     hash_entry);

    return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
}

static void batadv_tt_start_timer(struct batadv_priv *bat_priv)
{
    INIT_DELAYED_WORK(&bat_priv->tt.work, batadv_tt_purge);
    queue_delayed_work(batadv_event_workqueue, &bat_priv->tt.work,
               msecs_to_jiffies(5000));
}

static struct batadv_tt_common_entry *
batadv_tt_hash_find(struct batadv_hashtable *hash, const void *data)
{
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_common_entry *tt_common_entry_tmp = NULL;
    uint32_t index;

    if (!hash)
        return NULL;

    index = batadv_choose_orig(data, hash->size);
    head = &hash->table[index];

    rcu_read_lock();
    hlist_for_each_entry_rcu(tt_common_entry, node, head, hash_entry) {
        if (!batadv_compare_eth(tt_common_entry, data))
            continue;

        if (!atomic_inc_not_zero(&tt_common_entry->refcount))
            continue;

        tt_common_entry_tmp = tt_common_entry;
        break;
    }
    rcu_read_unlock();

    return tt_common_entry_tmp;
}

static struct batadv_tt_local_entry *
batadv_tt_local_hash_find(struct batadv_priv *bat_priv, const void *data)
{
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_local_entry *tt_local_entry = NULL;

    tt_common_entry = batadv_tt_hash_find(bat_priv->tt.local_hash, data);
    if (tt_common_entry)
        tt_local_entry = container_of(tt_common_entry,
                          struct batadv_tt_local_entry,
                          common);
    return tt_local_entry;
}

static struct batadv_tt_global_entry *
batadv_tt_global_hash_find(struct batadv_priv *bat_priv, const void *data)
{
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_global_entry *tt_global_entry = NULL;

    tt_common_entry = batadv_tt_hash_find(bat_priv->tt.global_hash, data);
    if (tt_common_entry)
        tt_global_entry = container_of(tt_common_entry,
                           struct batadv_tt_global_entry,
                           common);
    return tt_global_entry;

}

static void
batadv_tt_local_entry_free_ref(struct batadv_tt_local_entry *tt_local_entry)
{
    if (atomic_dec_and_test(&tt_local_entry->common.refcount))
        kfree_rcu(tt_local_entry, common.rcu);
}

static void batadv_tt_global_entry_free_rcu(struct rcu_head *rcu)
{
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_global_entry *tt_global_entry;

    tt_common_entry = container_of(rcu, struct batadv_tt_common_entry, rcu);
    tt_global_entry = container_of(tt_common_entry,
                       struct batadv_tt_global_entry, common);

    kfree(tt_global_entry);
}

static void
batadv_tt_global_entry_free_ref(struct batadv_tt_global_entry *tt_global_entry)
{
    if (atomic_dec_and_test(&tt_global_entry->common.refcount)) {
        batadv_tt_global_del_orig_list(tt_global_entry);
        call_rcu(&tt_global_entry->common.rcu,
             batadv_tt_global_entry_free_rcu);
    }
}

static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
{
    struct batadv_tt_orig_list_entry *orig_entry;

    orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);
    batadv_orig_node_free_ref(orig_entry->orig_node);
    kfree(orig_entry);
}

static void
batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
{
    if (!atomic_dec_and_test(&orig_entry->refcount))
        return;
    /* to avoid race conditions, immediately decrease the tt counter */
    atomic_dec(&orig_entry->orig_node->tt_size);
    call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
}

static void batadv_tt_local_event(struct batadv_priv *bat_priv,
                  const uint8_t *addr, uint8_t flags)
{
    struct batadv_tt_change_node *tt_change_node, *entry, *safe;
    bool event_removed = false;
    bool del_op_requested, del_op_entry;

    tt_change_node = kmalloc(sizeof(*tt_change_node), GFP_ATOMIC);

    if (!tt_change_node)
        return;

    tt_change_node->change.flags = flags;
    memcpy(tt_change_node->change.addr, addr, ETH_ALEN);

    del_op_requested = flags & BATADV_TT_CLIENT_DEL;

    /* check for ADD+DEL or DEL+ADD events */
    spin_lock_bh(&bat_priv->tt.changes_list_lock);
    list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                 list) {
        if (!batadv_compare_eth(entry->change.addr, addr))
            continue;

        /* DEL+ADD in the same orig interval have no effect and can be
         * removed to avoid silly behaviour on the receiver side. The
         * other way around (ADD+DEL) can happen in case of roaming of
         * a client still in the NEW state. Roaming of NEW clients is
         * now possible due to automatically recognition of "temporary"
         * clients
         */
        del_op_entry = entry->change.flags & BATADV_TT_CLIENT_DEL;
        if (!del_op_requested && del_op_entry)
            goto del;
        if (del_op_requested && !del_op_entry)
            goto del;
        continue;
del:
        list_del(&entry->list);
        kfree(entry);
        kfree(tt_change_node);
        event_removed = true;
        goto unlock;
    }

    /* track the change in the OGMinterval list */
    list_add_tail(&tt_change_node->list, &bat_priv->tt.changes_list);

unlock:
    spin_unlock_bh(&bat_priv->tt.changes_list_lock);

    if (event_removed)
        atomic_dec(&bat_priv->tt.local_changes);
    else
        atomic_inc(&bat_priv->tt.local_changes);
}

int batadv_tt_len(int changes_num)
{
    return changes_num * sizeof(struct batadv_tt_change);
}

static int batadv_tt_local_init(struct batadv_priv *bat_priv)
{
    if (bat_priv->tt.local_hash)
        return 0;

    bat_priv->tt.local_hash = batadv_hash_new(1024);

    if (!bat_priv->tt.local_hash)
        return -ENOMEM;

    return 0;
}

void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
             int ifindex)
{
    struct batadv_priv *bat_priv = netdev_priv(soft_iface);
    struct batadv_tt_local_entry *tt_local_entry = NULL;
    struct batadv_tt_global_entry *tt_global_entry = NULL;
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_orig_list_entry *orig_entry;
    int hash_added;

    tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);

    if (tt_local_entry) {
        tt_local_entry->last_seen = jiffies;
        /* possibly unset the BATADV_TT_CLIENT_PENDING flag */
        tt_local_entry->common.flags &= ~BATADV_TT_CLIENT_PENDING;
        goto out;
    }

    tt_local_entry = kmalloc(sizeof(*tt_local_entry), GFP_ATOMIC);
    if (!tt_local_entry)
        goto out;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Creating new local tt entry: %pM (ttvn: %d)\n", addr,
           (uint8_t)atomic_read(&bat_priv->tt.vn));

    memcpy(tt_local_entry->common.addr, addr, ETH_ALEN);
    tt_local_entry->common.flags = BATADV_NO_FLAGS;
    if (batadv_is_wifi_iface(ifindex))
        tt_local_entry->common.flags |= BATADV_TT_CLIENT_WIFI;
    atomic_set(&tt_local_entry->common.refcount, 2);
    tt_local_entry->last_seen = jiffies;
    tt_local_entry->common.added_at = tt_local_entry->last_seen;

    /* the batman interface mac address should never be purged */
    if (batadv_compare_eth(addr, soft_iface->dev_addr))
        tt_local_entry->common.flags |= BATADV_TT_CLIENT_NOPURGE;

    /* The local entry has to be marked as NEW to avoid to send it in
     * a full table response going out before the next ttvn increment
     * (consistency check)
     */
    tt_local_entry->common.flags |= BATADV_TT_CLIENT_NEW;

    hash_added = batadv_hash_add(bat_priv->tt.local_hash, batadv_compare_tt,
                     batadv_choose_orig,
                     &tt_local_entry->common,
                     &tt_local_entry->common.hash_entry);

    if (unlikely(hash_added != 0)) {
        /* remove the reference for the hash */
        batadv_tt_local_entry_free_ref(tt_local_entry);
        goto out;
    }

    batadv_tt_local_event(bat_priv, addr, tt_local_entry->common.flags);

    /* remove address from global hash if present */
    tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);

    /* Check whether it is a roaming! */
    if (tt_global_entry) {
        /* These node are probably going to update their tt table */
        head = &tt_global_entry->orig_list;
        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_entry, node, head, list) {
            orig_entry->orig_node->tt_poss_change = true;

            batadv_send_roam_adv(bat_priv,
                         tt_global_entry->common.addr,
                         orig_entry->orig_node);
        }
        rcu_read_unlock();
        /* The global entry has to be marked as ROAMING and
         * has to be kept for consistency purpose
         */
        tt_global_entry->common.flags |= BATADV_TT_CLIENT_ROAM;
        tt_global_entry->roam_at = jiffies;
    }
out:
    if (tt_local_entry)
        batadv_tt_local_entry_free_ref(tt_local_entry);
    if (tt_global_entry)
        batadv_tt_global_entry_free_ref(tt_global_entry);
}

static void batadv_tt_realloc_packet_buff(unsigned char **packet_buff,
                      int *packet_buff_len,
                      int min_packet_len,
                      int new_packet_len)
{
    unsigned char *new_buff;

    new_buff = kmalloc(new_packet_len, GFP_ATOMIC);

    /* keep old buffer if kmalloc should fail */
    if (new_buff) {
        memcpy(new_buff, *packet_buff, min_packet_len);
        kfree(*packet_buff);
        *packet_buff = new_buff;
        *packet_buff_len = new_packet_len;
    }
}

static void batadv_tt_prepare_packet_buff(struct batadv_priv *bat_priv,
                      unsigned char **packet_buff,
                      int *packet_buff_len,
                      int min_packet_len)
{
    struct batadv_hard_iface *primary_if;
    int req_len;

    primary_if = batadv_primary_if_get_selected(bat_priv);

    req_len = min_packet_len;
    req_len += batadv_tt_len(atomic_read(&bat_priv->tt.local_changes));

    /* if we have too many changes for one packet don't send any
     * and wait for the tt table request which will be fragmented
     */
    if ((!primary_if) || (req_len > primary_if->soft_iface->mtu))
        req_len = min_packet_len;

    batadv_tt_realloc_packet_buff(packet_buff, packet_buff_len,
                      min_packet_len, req_len);

    if (primary_if)
        batadv_hardif_free_ref(primary_if);
}

static int batadv_tt_changes_fill_buff(struct batadv_priv *bat_priv,
                       unsigned char **packet_buff,
                       int *packet_buff_len,
                       int min_packet_len)
{
    struct batadv_tt_change_node *entry, *safe;
    int count = 0, tot_changes = 0, new_len;
    unsigned char *tt_buff;

    batadv_tt_prepare_packet_buff(bat_priv, packet_buff,
                      packet_buff_len, min_packet_len);

    new_len = *packet_buff_len - min_packet_len;
    tt_buff = *packet_buff + min_packet_len;

    if (new_len > 0)
        tot_changes = new_len / batadv_tt_len(1);

    spin_lock_bh(&bat_priv->tt.changes_list_lock);
    atomic_set(&bat_priv->tt.local_changes, 0);

    list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                 list) {
        if (count < tot_changes) {
            memcpy(tt_buff + batadv_tt_len(count),
                   &entry->change, sizeof(struct batadv_tt_change));
            count++;
        }
        list_del(&entry->list);
        kfree(entry);
    }
    spin_unlock_bh(&bat_priv->tt.changes_list_lock);

    /* Keep the buffer for possible tt_request */
    spin_lock_bh(&bat_priv->tt.last_changeset_lock);
    kfree(bat_priv->tt.last_changeset);
    bat_priv->tt.last_changeset_len = 0;
    bat_priv->tt.last_changeset = NULL;
    /* check whether this new OGM has no changes due to size problems */
    if (new_len > 0) {
        /* if kmalloc() fails we will reply with the full table
         * instead of providing the diff
         */
        bat_priv->tt.last_changeset = kmalloc(new_len, GFP_ATOMIC);
        if (bat_priv->tt.last_changeset) {
            memcpy(bat_priv->tt.last_changeset, tt_buff, new_len);
            bat_priv->tt.last_changeset_len = new_len;
        }
    }
    spin_unlock_bh(&bat_priv->tt.last_changeset_lock);

    return count;
}

int batadv_tt_local_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->tt.local_hash;
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_hard_iface *primary_if;
    struct hlist_node *node;
    struct hlist_head *head;
    uint32_t i;
    int ret = 0;

    primary_if = batadv_primary_if_get_selected(bat_priv);
    if (!primary_if) {
        ret = seq_printf(seq,
                 "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
                 net_dev->name);
        goto out;
    }

    if (primary_if->if_status != BATADV_IF_ACTIVE) {
        ret = seq_printf(seq,
                 "BATMAN mesh %s disabled - primary interface not active\n",
                 net_dev->name);
        goto out;
    }

    seq_printf(seq,
           "Locally retrieved addresses (from %s) announced via TT (TTVN: %u):\n",
           net_dev->name, (uint8_t)atomic_read(&bat_priv->tt.vn));

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common_entry, node,
                     head, hash_entry) {
            seq_printf(seq, " * %pM [%c%c%c%c%c]\n",
                   tt_common_entry->addr,
                   (tt_common_entry->flags &
                    BATADV_TT_CLIENT_ROAM ? 'R' : '.'),
                   (tt_common_entry->flags &
                    BATADV_TT_CLIENT_NOPURGE ? 'P' : '.'),
                   (tt_common_entry->flags &
                    BATADV_TT_CLIENT_NEW ? 'N' : '.'),
                   (tt_common_entry->flags &
                    BATADV_TT_CLIENT_PENDING ? 'X' : '.'),
                   (tt_common_entry->flags &
                    BATADV_TT_CLIENT_WIFI ? 'W' : '.'));
        }
        rcu_read_unlock();
    }
out:
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    return ret;
}

static void
batadv_tt_local_set_pending(struct batadv_priv *bat_priv,
                struct batadv_tt_local_entry *tt_local_entry,
                uint16_t flags, const char *message)
{
    batadv_tt_local_event(bat_priv, tt_local_entry->common.addr,
                  tt_local_entry->common.flags | flags);

    /* The local client has to be marked as "pending to be removed" but has
     * to be kept in the table in order to send it in a full table
     * response issued before the net ttvn increment (consistency check)
     */
    tt_local_entry->common.flags |= BATADV_TT_CLIENT_PENDING;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Local tt entry (%pM) pending to be removed: %s\n",
           tt_local_entry->common.addr, message);
}

void batadv_tt_local_remove(struct batadv_priv *bat_priv, const uint8_t *addr,
                const char *message, bool roaming)
{
    struct batadv_tt_local_entry *tt_local_entry = NULL;
    uint16_t flags;

    tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);
    if (!tt_local_entry)
        goto out;

    flags = BATADV_TT_CLIENT_DEL;
    if (roaming)
        flags |= BATADV_TT_CLIENT_ROAM;

    batadv_tt_local_set_pending(bat_priv, tt_local_entry, flags, message);
out:
    if (tt_local_entry)
        batadv_tt_local_entry_free_ref(tt_local_entry);
}

static void batadv_tt_local_purge_list(struct batadv_priv *bat_priv,
                       struct hlist_head *head)
{
    struct batadv_tt_local_entry *tt_local_entry;
    struct batadv_tt_common_entry *tt_common_entry;
    struct hlist_node *node, *node_tmp;

    hlist_for_each_entry_safe(tt_common_entry, node, node_tmp, head,
                  hash_entry) {
        tt_local_entry = container_of(tt_common_entry,
                          struct batadv_tt_local_entry,
                          common);
        if (tt_local_entry->common.flags & BATADV_TT_CLIENT_NOPURGE)
            continue;

        /* entry already marked for deletion */
        if (tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING)
            continue;

        if (!batadv_has_timed_out(tt_local_entry->last_seen,
                      BATADV_TT_LOCAL_TIMEOUT))
            continue;

        batadv_tt_local_set_pending(bat_priv, tt_local_entry,
                        BATADV_TT_CLIENT_DEL, "timed out");
    }
}

static void batadv_tt_local_purge(struct batadv_priv *bat_priv)
{
    struct batadv_hashtable *hash = bat_priv->tt.local_hash;
    struct hlist_head *head;
    spinlock_t *list_lock; /* protects write access to the hash lists */
    uint32_t i;

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

        spin_lock_bh(list_lock);
        batadv_tt_local_purge_list(bat_priv, head);
        spin_unlock_bh(list_lock);
    }

}

static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
{
    struct batadv_hashtable *hash;
    spinlock_t *list_lock; /* protects write access to the hash lists */
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_local_entry *tt_local;
    struct hlist_node *node, *node_tmp;
    struct hlist_head *head;
    uint32_t i;

    if (!bat_priv->tt.local_hash)
        return;

    hash = bat_priv->tt.local_hash;

    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(tt_common_entry, node, node_tmp,
                      head, hash_entry) {
            hlist_del_rcu(node);
            tt_local = container_of(tt_common_entry,
                        struct batadv_tt_local_entry,
                        common);
            batadv_tt_local_entry_free_ref(tt_local);
        }
        spin_unlock_bh(list_lock);
    }

    batadv_hash_destroy(hash);

    bat_priv->tt.local_hash = NULL;
}

static int batadv_tt_global_init(struct batadv_priv *bat_priv)
{
    if (bat_priv->tt.global_hash)
        return 0;

    bat_priv->tt.global_hash = batadv_hash_new(1024);

    if (!bat_priv->tt.global_hash)
        return -ENOMEM;

    return 0;
}

static void batadv_tt_changes_list_free(struct batadv_priv *bat_priv)
{
    struct batadv_tt_change_node *entry, *safe;

    spin_lock_bh(&bat_priv->tt.changes_list_lock);

    list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                 list) {
        list_del(&entry->list);
        kfree(entry);
    }

    atomic_set(&bat_priv->tt.local_changes, 0);
    spin_unlock_bh(&bat_priv->tt.changes_list_lock);
}

/* retrieves the orig_tt_list_entry belonging to orig_node from the
 * batadv_tt_global_entry list
 *
 * returns it with an increased refcounter, NULL if not found
 */
static struct batadv_tt_orig_list_entry *
batadv_tt_global_orig_entry_find(const struct batadv_tt_global_entry *entry,
                 const struct batadv_orig_node *orig_node)
{
    struct batadv_tt_orig_list_entry *tmp_orig_entry, *orig_entry = NULL;
    const struct hlist_head *head;
    struct hlist_node *node;

    rcu_read_lock();
    head = &entry->orig_list;
    hlist_for_each_entry_rcu(tmp_orig_entry, node, head, list) {
        if (tmp_orig_entry->orig_node != orig_node)
            continue;
        if (!atomic_inc_not_zero(&tmp_orig_entry->refcount))
            continue;

        orig_entry = tmp_orig_entry;
        break;
    }
    rcu_read_unlock();

    return orig_entry;
}

/* find out if an orig_node is already in the list of a tt_global_entry.
 * returns true if found, false otherwise
 */
static bool
batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
                const struct batadv_orig_node *orig_node)
{
    struct batadv_tt_orig_list_entry *orig_entry;
    bool found = false;

    orig_entry = batadv_tt_global_orig_entry_find(entry, orig_node);
    if (orig_entry) {
        found = true;
        batadv_tt_orig_list_entry_free_ref(orig_entry);
    }

    return found;
}

static void
batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global,
                struct batadv_orig_node *orig_node, int ttvn)
{
    struct batadv_tt_orig_list_entry *orig_entry;

    orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node);
    if (orig_entry) {
        /* refresh the ttvn: the current value could be a bogus one that
         * was added during a "temporary client detection"
         */
        orig_entry->ttvn = ttvn;
        goto out;
    }

    orig_entry = kzalloc(sizeof(*orig_entry), GFP_ATOMIC);
    if (!orig_entry)
        goto out;

    INIT_HLIST_NODE(&orig_entry->list);
    atomic_inc(&orig_node->refcount);
    atomic_inc(&orig_node->tt_size);
    orig_entry->orig_node = orig_node;
    orig_entry->ttvn = ttvn;
    atomic_set(&orig_entry->refcount, 2);

    spin_lock_bh(&tt_global->list_lock);
    hlist_add_head_rcu(&orig_entry->list,
               &tt_global->orig_list);
    spin_unlock_bh(&tt_global->list_lock);
out:
    if (orig_entry)
        batadv_tt_orig_list_entry_free_ref(orig_entry);
}

/* caller must hold orig_node refcount */
int batadv_tt_global_add(struct batadv_priv *bat_priv,
             struct batadv_orig_node *orig_node,
             const unsigned char *tt_addr, uint8_t flags,
             uint8_t ttvn)
{
    struct batadv_tt_global_entry *tt_global_entry = NULL;
    int ret = 0;
    int hash_added;
    struct batadv_tt_common_entry *common;

    tt_global_entry = batadv_tt_global_hash_find(bat_priv, tt_addr);

    if (!tt_global_entry) {
        tt_global_entry = kzalloc(sizeof(*tt_global_entry), GFP_ATOMIC);
        if (!tt_global_entry)
            goto out;

        common = &tt_global_entry->common;
        memcpy(common->addr, tt_addr, ETH_ALEN);

        common->flags = flags;
        tt_global_entry->roam_at = 0;
        atomic_set(&common->refcount, 2);
        common->added_at = jiffies;

        INIT_HLIST_HEAD(&tt_global_entry->orig_list);
        spin_lock_init(&tt_global_entry->list_lock);

        hash_added = batadv_hash_add(bat_priv->tt.global_hash,
                         batadv_compare_tt,
                         batadv_choose_orig, common,
                         &common->hash_entry);

        if (unlikely(hash_added != 0)) {
            /* remove the reference for the hash */
            batadv_tt_global_entry_free_ref(tt_global_entry);
            goto out_remove;
        }
    } else {
        /* If there is already a global entry, we can use this one for
         * our processing.
         * But if we are trying to add a temporary client we can exit
         * directly because the temporary information should never
         * override any already known client state (whatever it is)
         */
        if (flags & BATADV_TT_CLIENT_TEMP)
            goto out;

        /* if the client was temporary added before receiving the first
         * OGM announcing it, we have to clear the TEMP flag
         */
        tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_TEMP;

        /* the change can carry possible "attribute" flags like the
         * TT_CLIENT_WIFI, therefore they have to be copied in the
         * client entry
         */
        tt_global_entry->common.flags |= flags;

        /* If there is the BATADV_TT_CLIENT_ROAM flag set, there is only
         * one originator left in the list and we previously received a
         * delete + roaming change for this originator.
         *
         * We should first delete the old originator before adding the
         * new one.
         */
        if (tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM) {
            batadv_tt_global_del_orig_list(tt_global_entry);
            tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_ROAM;
            tt_global_entry->roam_at = 0;
        }
    }
    /* add the new orig_entry (if needed) or update it */
    batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Creating new global tt entry: %pM (via %pM)\n",
           tt_global_entry->common.addr, orig_node->orig);

out_remove:
    /* remove address from local hash if present */
    batadv_tt_local_remove(bat_priv, tt_global_entry->common.addr,
                   "global tt received",
                   flags & BATADV_TT_CLIENT_ROAM);
    ret = 1;
out:
    if (tt_global_entry)
        batadv_tt_global_entry_free_ref(tt_global_entry);
    return ret;
}

/* print all orig nodes who announce the address for this global entry.
 * it is assumed that the caller holds rcu_read_lock();
 */
static void
batadv_tt_global_print_entry(struct batadv_tt_global_entry *tt_global_entry,
                 struct seq_file *seq)
{
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_orig_list_entry *orig_entry;
    struct batadv_tt_common_entry *tt_common_entry;
    uint16_t flags;
    uint8_t last_ttvn;

    tt_common_entry = &tt_global_entry->common;

    head = &tt_global_entry->orig_list;

    hlist_for_each_entry_rcu(orig_entry, node, head, list) {
        flags = tt_common_entry->flags;
        last_ttvn = atomic_read(&orig_entry->orig_node->last_ttvn);
        seq_printf(seq, " * %pM  (%3u) via %pM     (%3u)   [%c%c%c]\n",
               tt_global_entry->common.addr, orig_entry->ttvn,
               orig_entry->orig_node->orig, last_ttvn,
               (flags & BATADV_TT_CLIENT_ROAM ? 'R' : '.'),
               (flags & BATADV_TT_CLIENT_WIFI ? 'W' : '.'),
               (flags & BATADV_TT_CLIENT_TEMP ? 'T' : '.'));
    }
}

int batadv_tt_global_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->tt.global_hash;
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_global_entry *tt_global;
    struct batadv_hard_iface *primary_if;
    struct hlist_node *node;
    struct hlist_head *head;
    uint32_t i;
    int ret = 0;

    primary_if = batadv_primary_if_get_selected(bat_priv);
    if (!primary_if) {
        ret = seq_printf(seq,
                 "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
                 net_dev->name);
        goto out;
    }

    if (primary_if->if_status != BATADV_IF_ACTIVE) {
        ret = seq_printf(seq,
                 "BATMAN mesh %s disabled - primary interface not active\n",
                 net_dev->name);
        goto out;
    }

    seq_printf(seq,
           "Globally announced TT entries received via the mesh %s\n",
           net_dev->name);
    seq_printf(seq, "       %-13s %s       %-15s %s %s\n",
           "Client", "(TTVN)", "Originator", "(Curr TTVN)", "Flags");

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common_entry, node,
                     head, hash_entry) {
            tt_global = container_of(tt_common_entry,
                         struct batadv_tt_global_entry,
                         common);
            batadv_tt_global_print_entry(tt_global, seq);
        }
        rcu_read_unlock();
    }
out:
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    return ret;
}

/* deletes the orig list of a tt_global_entry */
static void
batadv_tt_global_del_orig_list(struct batadv_tt_global_entry *tt_global_entry)
{
    struct hlist_head *head;
    struct hlist_node *node, *safe;
    struct batadv_tt_orig_list_entry *orig_entry;

    spin_lock_bh(&tt_global_entry->list_lock);
    head = &tt_global_entry->orig_list;
    hlist_for_each_entry_safe(orig_entry, node, safe, head, list) {
        hlist_del_rcu(node);
        batadv_tt_orig_list_entry_free_ref(orig_entry);
    }
    spin_unlock_bh(&tt_global_entry->list_lock);

}

static void
batadv_tt_global_del_orig_entry(struct batadv_priv *bat_priv,
                struct batadv_tt_global_entry *tt_global_entry,
                struct batadv_orig_node *orig_node,
                const char *message)
{
    struct hlist_head *head;
    struct hlist_node *node, *safe;
    struct batadv_tt_orig_list_entry *orig_entry;

    spin_lock_bh(&tt_global_entry->list_lock);
    head = &tt_global_entry->orig_list;
    hlist_for_each_entry_safe(orig_entry, node, safe, head, list) {
        if (orig_entry->orig_node == orig_node) {
            batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Deleting %pM from global tt entry %pM: %s\n",
                   orig_node->orig,
                   tt_global_entry->common.addr, message);
            hlist_del_rcu(node);
            batadv_tt_orig_list_entry_free_ref(orig_entry);
        }
    }
    spin_unlock_bh(&tt_global_entry->list_lock);
}

static void
batadv_tt_global_del_struct(struct batadv_priv *bat_priv,
                struct batadv_tt_global_entry *tt_global_entry,
                const char *message)
{
    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Deleting global tt entry %pM: %s\n",
           tt_global_entry->common.addr, message);

    batadv_hash_remove(bat_priv->tt.global_hash, batadv_compare_tt,
               batadv_choose_orig, tt_global_entry->common.addr);
    batadv_tt_global_entry_free_ref(tt_global_entry);

}

/* If the client is to be deleted, we check if it is the last origantor entry
 * within tt_global entry. If yes, we set the BATADV_TT_CLIENT_ROAM flag and the
 * timer, otherwise we simply remove the originator scheduled for deletion.
 */
static void
batadv_tt_global_del_roaming(struct batadv_priv *bat_priv,
                 struct batadv_tt_global_entry *tt_global_entry,
                 struct batadv_orig_node *orig_node,
                 const char *message)
{
    bool last_entry = true;
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_orig_list_entry *orig_entry;

    /* no local entry exists, case 1:
     * Check if this is the last one or if other entries exist.
     */

    rcu_read_lock();
    head = &tt_global_entry->orig_list;
    hlist_for_each_entry_rcu(orig_entry, node, head, list) {
        if (orig_entry->orig_node != orig_node) {
            last_entry = false;
            break;
        }
    }
    rcu_read_unlock();

    if (last_entry) {
        /* its the last one, mark for roaming. */
        tt_global_entry->common.flags |= BATADV_TT_CLIENT_ROAM;
        tt_global_entry->roam_at = jiffies;
    } else
        /* there is another entry, we can simply delete this
         * one and can still use the other one.
         */
        batadv_tt_global_del_orig_entry(bat_priv, tt_global_entry,
                        orig_node, message);
}



static void batadv_tt_global_del(struct batadv_priv *bat_priv,
                 struct batadv_orig_node *orig_node,
                 const unsigned char *addr,
                 const char *message, bool roaming)
{
    struct batadv_tt_global_entry *tt_global_entry = NULL;
    struct batadv_tt_local_entry *local_entry = NULL;

    tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
    if (!tt_global_entry)
        goto out;

    if (!roaming) {
        batadv_tt_global_del_orig_entry(bat_priv, tt_global_entry,
                        orig_node, message);

        if (hlist_empty(&tt_global_entry->orig_list))
            batadv_tt_global_del_struct(bat_priv, tt_global_entry,
                            message);

        goto out;
    }

    /* if we are deleting a global entry due to a roam
     * event, there are two possibilities:
     * 1) the client roamed from node A to node B => if there
     *    is only one originator left for this client, we mark
     *    it with BATADV_TT_CLIENT_ROAM, we start a timer and we
     *    wait for node B to claim it. In case of timeout
     *    the entry is purged.
     *
     *    If there are other originators left, we directly delete
     *    the originator.
     * 2) the client roamed to us => we can directly delete
     *    the global entry, since it is useless now.
     */
    local_entry = batadv_tt_local_hash_find(bat_priv,
                        tt_global_entry->common.addr);
    if (local_entry) {
        /* local entry exists, case 2: client roamed to us. */
        batadv_tt_global_del_orig_list(tt_global_entry);
        batadv_tt_global_del_struct(bat_priv, tt_global_entry, message);
    } else
        /* no local entry exists, case 1: check for roaming */
        batadv_tt_global_del_roaming(bat_priv, tt_global_entry,
                         orig_node, message);


out:
    if (tt_global_entry)
        batadv_tt_global_entry_free_ref(tt_global_entry);
    if (local_entry)
        batadv_tt_local_entry_free_ref(local_entry);
}

void batadv_tt_global_del_orig(struct batadv_priv *bat_priv,
                   struct batadv_orig_node *orig_node,
                   const char *message)
{
    struct batadv_tt_global_entry *tt_global;
    struct batadv_tt_common_entry *tt_common_entry;
    uint32_t i;
    struct batadv_hashtable *hash = bat_priv->tt.global_hash;
    struct hlist_node *node, *safe;
    struct hlist_head *head;
    spinlock_t *list_lock; /* protects write access to the hash lists */

    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(tt_common_entry, node, safe,
                      head, hash_entry) {
            tt_global = container_of(tt_common_entry,
                         struct batadv_tt_global_entry,
                         common);

            batadv_tt_global_del_orig_entry(bat_priv, tt_global,
                            orig_node, message);

            if (hlist_empty(&tt_global->orig_list)) {
                batadv_dbg(BATADV_DBG_TT, bat_priv,
                       "Deleting global tt entry %pM: %s\n",
                       tt_global->common.addr, message);
                hlist_del_rcu(node);
                batadv_tt_global_entry_free_ref(tt_global);
            }
        }
        spin_unlock_bh(list_lock);
    }
    orig_node->tt_initialised = false;
}

static bool batadv_tt_global_to_purge(struct batadv_tt_global_entry *tt_global,
                      char **msg)
{
    bool purge = false;
    unsigned long roam_timeout = BATADV_TT_CLIENT_ROAM_TIMEOUT;
    unsigned long temp_timeout = BATADV_TT_CLIENT_TEMP_TIMEOUT;

    if ((tt_global->common.flags & BATADV_TT_CLIENT_ROAM) &&
        batadv_has_timed_out(tt_global->roam_at, roam_timeout)) {
        purge = true;
        *msg = "Roaming timeout\n";
    }

    if ((tt_global->common.flags & BATADV_TT_CLIENT_TEMP) &&
        batadv_has_timed_out(tt_global->common.added_at, temp_timeout)) {
        purge = true;
        *msg = "Temporary client timeout\n";
    }

    return purge;
}

static void batadv_tt_global_purge(struct batadv_priv *bat_priv)
{
    struct batadv_hashtable *hash = bat_priv->tt.global_hash;
    struct hlist_head *head;
    struct hlist_node *node, *node_tmp;
    spinlock_t *list_lock; /* protects write access to the hash lists */
    uint32_t i;
    char *msg = NULL;
    struct batadv_tt_common_entry *tt_common;
    struct batadv_tt_global_entry *tt_global;

    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(tt_common, node, node_tmp, head,
                      hash_entry) {
            tt_global = container_of(tt_common,
                         struct batadv_tt_global_entry,
                         common);

            if (!batadv_tt_global_to_purge(tt_global, &msg))
                continue;

            batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Deleting global tt entry (%pM): %s\n",
                   tt_global->common.addr, msg);

            hlist_del_rcu(node);

            batadv_tt_global_entry_free_ref(tt_global);
        }
        spin_unlock_bh(list_lock);
    }
}

static void batadv_tt_global_table_free(struct batadv_priv *bat_priv)
{
    struct batadv_hashtable *hash;
    spinlock_t *list_lock; /* protects write access to the hash lists */
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_global_entry *tt_global;
    struct hlist_node *node, *node_tmp;
    struct hlist_head *head;
    uint32_t i;

    if (!bat_priv->tt.global_hash)
        return;

    hash = bat_priv->tt.global_hash;

    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(tt_common_entry, node, node_tmp,
                      head, hash_entry) {
            hlist_del_rcu(node);
            tt_global = container_of(tt_common_entry,
                         struct batadv_tt_global_entry,
                         common);
            batadv_tt_global_entry_free_ref(tt_global);
        }
        spin_unlock_bh(list_lock);
    }

    batadv_hash_destroy(hash);

    bat_priv->tt.global_hash = NULL;
}

static bool
_batadv_is_ap_isolated(struct batadv_tt_local_entry *tt_local_entry,
               struct batadv_tt_global_entry *tt_global_entry)
{
    bool ret = false;

    if (tt_local_entry->common.flags & BATADV_TT_CLIENT_WIFI &&
        tt_global_entry->common.flags & BATADV_TT_CLIENT_WIFI)
        ret = true;

    return ret;
}

struct batadv_orig_node *batadv_transtable_search(struct batadv_priv *bat_priv,
                          const uint8_t *src,
                          const uint8_t *addr)
{
    struct batadv_tt_local_entry *tt_local_entry = NULL;
    struct batadv_tt_global_entry *tt_global_entry = NULL;
    struct batadv_orig_node *orig_node = NULL;
    struct batadv_neigh_node *router = NULL;
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_orig_list_entry *orig_entry;
    int best_tq;

    if (src && atomic_read(&bat_priv->ap_isolation)) {
        tt_local_entry = batadv_tt_local_hash_find(bat_priv, src);
        if (!tt_local_entry)
            goto out;
    }

    tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
    if (!tt_global_entry)
        goto out;

    /* check whether the clients should not communicate due to AP
     * isolation
     */
    if (tt_local_entry &&
        _batadv_is_ap_isolated(tt_local_entry, tt_global_entry))
        goto out;

    best_tq = 0;

    rcu_read_lock();
    head = &tt_global_entry->orig_list;
    hlist_for_each_entry_rcu(orig_entry, node, head, list) {
        router = batadv_orig_node_get_router(orig_entry->orig_node);
        if (!router)
            continue;

        if (router->tq_avg > best_tq) {
            orig_node = orig_entry->orig_node;
            best_tq = router->tq_avg;
        }
        batadv_neigh_node_free_ref(router);
    }
    /* found anything? */
    if (orig_node && !atomic_inc_not_zero(&orig_node->refcount))
        orig_node = NULL;
    rcu_read_unlock();
out:
    if (tt_global_entry)
        batadv_tt_global_entry_free_ref(tt_global_entry);
    if (tt_local_entry)
        batadv_tt_local_entry_free_ref(tt_local_entry);

    return orig_node;
}

/* Calculates the checksum of the local table of a given orig_node */
static uint16_t batadv_tt_global_crc(struct batadv_priv *bat_priv,
                     struct batadv_orig_node *orig_node)
{
    uint16_t total = 0, total_one;
    struct batadv_hashtable *hash = bat_priv->tt.global_hash;
    struct batadv_tt_common_entry *tt_common;
    struct batadv_tt_global_entry *tt_global;
    struct hlist_node *node;
    struct hlist_head *head;
    uint32_t i;
    int j;

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common, node, head, hash_entry) {
            tt_global = container_of(tt_common,
                         struct batadv_tt_global_entry,
                         common);
            /* Roaming clients are in the global table for
             * consistency only. They don't have to be
             * taken into account while computing the
             * global crc
             */
            if (tt_common->flags & BATADV_TT_CLIENT_ROAM)
                continue;
            /* Temporary clients have not been announced yet, so
             * they have to be skipped while computing the global
             * crc
             */
            if (tt_common->flags & BATADV_TT_CLIENT_TEMP)
                continue;

            /* find out if this global entry is announced by this
             * originator
             */
            if (!batadv_tt_global_entry_has_orig(tt_global,
                                 orig_node))
                continue;

            total_one = 0;
            for (j = 0; j < ETH_ALEN; j++)
                total_one = crc16_byte(total_one,
                               tt_common->addr[j]);
            total ^= total_one;
        }
        rcu_read_unlock();
    }

    return total;
}

/* Calculates the checksum of the local table */
static uint16_t batadv_tt_local_crc(struct batadv_priv *bat_priv)
{
    uint16_t total = 0, total_one;
    struct batadv_hashtable *hash = bat_priv->tt.local_hash;
    struct batadv_tt_common_entry *tt_common;
    struct hlist_node *node;
    struct hlist_head *head;
    uint32_t i;
    int j;

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common, node, head, hash_entry) {
            /* not yet committed clients have not to be taken into
             * account while computing the CRC
             */
            if (tt_common->flags & BATADV_TT_CLIENT_NEW)
                continue;
            total_one = 0;
            for (j = 0; j < ETH_ALEN; j++)
                total_one = crc16_byte(total_one,
                               tt_common->addr[j]);
            total ^= total_one;
        }
        rcu_read_unlock();
    }

    return total;
}

static void batadv_tt_req_list_free(struct batadv_priv *bat_priv)
{
    struct batadv_tt_req_node *node, *safe;

    spin_lock_bh(&bat_priv->tt.req_list_lock);

    list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
        list_del(&node->list);
        kfree(node);
    }

    spin_unlock_bh(&bat_priv->tt.req_list_lock);
}

static void batadv_tt_save_orig_buffer(struct batadv_priv *bat_priv,
                       struct batadv_orig_node *orig_node,
                       const unsigned char *tt_buff,
                       uint8_t tt_num_changes)
{
    uint16_t tt_buff_len = batadv_tt_len(tt_num_changes);

    /* Replace the old buffer only if I received something in the
     * last OGM (the OGM could carry no changes)
     */
    spin_lock_bh(&orig_node->tt_buff_lock);
    if (tt_buff_len > 0) {
        kfree(orig_node->tt_buff);
        orig_node->tt_buff_len = 0;
        orig_node->tt_buff = kmalloc(tt_buff_len, GFP_ATOMIC);
        if (orig_node->tt_buff) {
            memcpy(orig_node->tt_buff, tt_buff, tt_buff_len);
            orig_node->tt_buff_len = tt_buff_len;
        }
    }
    spin_unlock_bh(&orig_node->tt_buff_lock);
}

static void batadv_tt_req_purge(struct batadv_priv *bat_priv)
{
    struct batadv_tt_req_node *node, *safe;

    spin_lock_bh(&bat_priv->tt.req_list_lock);
    list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
        if (batadv_has_timed_out(node->issued_at,
                     BATADV_TT_REQUEST_TIMEOUT)) {
            list_del(&node->list);
            kfree(node);
        }
    }
    spin_unlock_bh(&bat_priv->tt.req_list_lock);
}

/* returns the pointer to the new tt_req_node struct if no request
 * has already been issued for this orig_node, NULL otherwise
 */
static struct batadv_tt_req_node *
batadv_new_tt_req_node(struct batadv_priv *bat_priv,
               struct batadv_orig_node *orig_node)
{
    struct batadv_tt_req_node *tt_req_node_tmp, *tt_req_node = NULL;

    spin_lock_bh(&bat_priv->tt.req_list_lock);
    list_for_each_entry(tt_req_node_tmp, &bat_priv->tt.req_list, list) {
        if (batadv_compare_eth(tt_req_node_tmp, orig_node) &&
            !batadv_has_timed_out(tt_req_node_tmp->issued_at,
                      BATADV_TT_REQUEST_TIMEOUT))
            goto unlock;
    }

    tt_req_node = kmalloc(sizeof(*tt_req_node), GFP_ATOMIC);
    if (!tt_req_node)
        goto unlock;

    memcpy(tt_req_node->addr, orig_node->orig, ETH_ALEN);
    tt_req_node->issued_at = jiffies;

    list_add(&tt_req_node->list, &bat_priv->tt.req_list);
unlock:
    spin_unlock_bh(&bat_priv->tt.req_list_lock);
    return tt_req_node;
}

/* data_ptr is useless here, but has to be kept to respect the prototype */
static int batadv_tt_local_valid_entry(const void *entry_ptr,
                       const void *data_ptr)
{
    const struct batadv_tt_common_entry *tt_common_entry = entry_ptr;

    if (tt_common_entry->flags & BATADV_TT_CLIENT_NEW)
        return 0;
    return 1;
}

static int batadv_tt_global_valid(const void *entry_ptr,
                  const void *data_ptr)
{
    const struct batadv_tt_common_entry *tt_common_entry = entry_ptr;
    const struct batadv_tt_global_entry *tt_global_entry;
    const struct batadv_orig_node *orig_node = data_ptr;

    if (tt_common_entry->flags & BATADV_TT_CLIENT_ROAM ||
        tt_common_entry->flags & BATADV_TT_CLIENT_TEMP)
        return 0;

    tt_global_entry = container_of(tt_common_entry,
                       struct batadv_tt_global_entry,
                       common);

    return batadv_tt_global_entry_has_orig(tt_global_entry, orig_node);
}

static struct sk_buff *
batadv_tt_response_fill_table(uint16_t tt_len, uint8_t ttvn,
                  struct batadv_hashtable *hash,
                  struct batadv_hard_iface *primary_if,
                  int (*valid_cb)(const void *, const void *),
                  void *cb_data)
{
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_query_packet *tt_response;
    struct batadv_tt_change *tt_change;
    struct hlist_node *node;
    struct hlist_head *head;
    struct sk_buff *skb = NULL;
    uint16_t tt_tot, tt_count;
    ssize_t tt_query_size = sizeof(struct batadv_tt_query_packet);
    uint32_t i;
    size_t len;

    if (tt_query_size + tt_len > primary_if->soft_iface->mtu) {
        tt_len = primary_if->soft_iface->mtu - tt_query_size;
        tt_len -= tt_len % sizeof(struct batadv_tt_change);
    }
    tt_tot = tt_len / sizeof(struct batadv_tt_change);

    len = tt_query_size + tt_len;
    skb = dev_alloc_skb(len + ETH_HLEN);
    if (!skb)
        goto out;

    skb_reserve(skb, ETH_HLEN);
    tt_response = (struct batadv_tt_query_packet *)skb_put(skb, len);
    tt_response->ttvn = ttvn;

    tt_change = (struct batadv_tt_change *)(skb->data + tt_query_size);
    tt_count = 0;

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

        hlist_for_each_entry_rcu(tt_common_entry, node,
                     head, hash_entry) {
            if (tt_count == tt_tot)
                break;

            if ((valid_cb) && (!valid_cb(tt_common_entry, cb_data)))
                continue;

            memcpy(tt_change->addr, tt_common_entry->addr,
                   ETH_ALEN);
            tt_change->flags = tt_common_entry->flags;

            tt_count++;
            tt_change++;
        }
    }
    rcu_read_unlock();

    /* store in the message the number of entries we have successfully
     * copied
     */
    tt_response->tt_data = htons(tt_count);

out:
    return skb;
}

static int batadv_send_tt_request(struct batadv_priv *bat_priv,
                  struct batadv_orig_node *dst_orig_node,
                  uint8_t ttvn, uint16_t tt_crc,
                  bool full_table)
{
    struct sk_buff *skb = NULL;
    struct batadv_tt_query_packet *tt_request;
    struct batadv_neigh_node *neigh_node = NULL;
    struct batadv_hard_iface *primary_if;
    struct batadv_tt_req_node *tt_req_node = NULL;
    int ret = 1;
    size_t tt_req_len;

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

    /* The new tt_req will be issued only if I'm not waiting for a
     * reply from the same orig_node yet
     */
    tt_req_node = batadv_new_tt_req_node(bat_priv, dst_orig_node);
    if (!tt_req_node)
        goto out;

    skb = dev_alloc_skb(sizeof(*tt_request) + ETH_HLEN);
    if (!skb)
        goto out;

    skb_reserve(skb, ETH_HLEN);

    tt_req_len = sizeof(*tt_request);
    tt_request = (struct batadv_tt_query_packet *)skb_put(skb, tt_req_len);

    tt_request->header.packet_type = BATADV_TT_QUERY;
    tt_request->header.version = BATADV_COMPAT_VERSION;
    memcpy(tt_request->src, primary_if->net_dev->dev_addr, ETH_ALEN);
    memcpy(tt_request->dst, dst_orig_node->orig, ETH_ALEN);
    tt_request->header.ttl = BATADV_TTL;
    tt_request->ttvn = ttvn;
    tt_request->tt_data = htons(tt_crc);
    tt_request->flags = BATADV_TT_REQUEST;

    if (full_table)
        tt_request->flags |= BATADV_TT_FULL_TABLE;

    neigh_node = batadv_orig_node_get_router(dst_orig_node);
    if (!neigh_node)
        goto out;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Sending TT_REQUEST to %pM via %pM [%c]\n",
           dst_orig_node->orig, neigh_node->addr,
           (full_table ? 'F' : '.'));

    batadv_inc_counter(bat_priv, BATADV_CNT_TT_REQUEST_TX);

    batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
    ret = 0;

out:
    if (neigh_node)
        batadv_neigh_node_free_ref(neigh_node);
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    if (ret)
        kfree_skb(skb);
    if (ret && tt_req_node) {
        spin_lock_bh(&bat_priv->tt.req_list_lock);
        list_del(&tt_req_node->list);
        spin_unlock_bh(&bat_priv->tt.req_list_lock);
        kfree(tt_req_node);
    }
    return ret;
}

static bool
batadv_send_other_tt_response(struct batadv_priv *bat_priv,
                  struct batadv_tt_query_packet *tt_request)
{
    struct batadv_orig_node *req_dst_orig_node = NULL;
    struct batadv_orig_node *res_dst_orig_node = NULL;
    struct batadv_neigh_node *neigh_node = NULL;
    struct batadv_hard_iface *primary_if = NULL;
    uint8_t orig_ttvn, req_ttvn, ttvn;
    int ret = false;
    unsigned char *tt_buff;
    bool full_table;
    uint16_t tt_len, tt_tot;
    struct sk_buff *skb = NULL;
    struct batadv_tt_query_packet *tt_response;
    uint8_t *packet_pos;
    size_t len;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Received TT_REQUEST from %pM for ttvn: %u (%pM) [%c]\n",
           tt_request->src, tt_request->ttvn, tt_request->dst,
           (tt_request->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

    /* Let's get the orig node of the REAL destination */
    req_dst_orig_node = batadv_orig_hash_find(bat_priv, tt_request->dst);
    if (!req_dst_orig_node)
        goto out;

    res_dst_orig_node = batadv_orig_hash_find(bat_priv, tt_request->src);
    if (!res_dst_orig_node)
        goto out;

    neigh_node = batadv_orig_node_get_router(res_dst_orig_node);
    if (!neigh_node)
        goto out;

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

    orig_ttvn = (uint8_t)atomic_read(&req_dst_orig_node->last_ttvn);
    req_ttvn = tt_request->ttvn;

    /* I don't have the requested data */
    if (orig_ttvn != req_ttvn ||
        tt_request->tt_data != htons(req_dst_orig_node->tt_crc))
        goto out;

    /* If the full table has been explicitly requested */
    if (tt_request->flags & BATADV_TT_FULL_TABLE ||
        !req_dst_orig_node->tt_buff)
        full_table = true;
    else
        full_table = false;

    /* In this version, fragmentation is not implemented, then
     * I'll send only one packet with as much TT entries as I can
     */
    if (!full_table) {
        spin_lock_bh(&req_dst_orig_node->tt_buff_lock);
        tt_len = req_dst_orig_node->tt_buff_len;
        tt_tot = tt_len / sizeof(struct batadv_tt_change);

        len = sizeof(*tt_response) + tt_len;
        skb = dev_alloc_skb(len + ETH_HLEN);
        if (!skb)
            goto unlock;

        skb_reserve(skb, ETH_HLEN);
        packet_pos = skb_put(skb, len);
        tt_response = (struct batadv_tt_query_packet *)packet_pos;
        tt_response->ttvn = req_ttvn;
        tt_response->tt_data = htons(tt_tot);

        tt_buff = skb->data + sizeof(*tt_response);
        /* Copy the last orig_node's OGM buffer */
        memcpy(tt_buff, req_dst_orig_node->tt_buff,
               req_dst_orig_node->tt_buff_len);

        spin_unlock_bh(&req_dst_orig_node->tt_buff_lock);
    } else {
        tt_len = (uint16_t)atomic_read(&req_dst_orig_node->tt_size);
        tt_len *= sizeof(struct batadv_tt_change);
        ttvn = (uint8_t)atomic_read(&req_dst_orig_node->last_ttvn);

        skb = batadv_tt_response_fill_table(tt_len, ttvn,
                            bat_priv->tt.global_hash,
                            primary_if,
                            batadv_tt_global_valid,
                            req_dst_orig_node);
        if (!skb)
            goto out;

        tt_response = (struct batadv_tt_query_packet *)skb->data;
    }

    tt_response->header.packet_type = BATADV_TT_QUERY;
    tt_response->header.version = BATADV_COMPAT_VERSION;
    tt_response->header.ttl = BATADV_TTL;
    memcpy(tt_response->src, req_dst_orig_node->orig, ETH_ALEN);
    memcpy(tt_response->dst, tt_request->src, ETH_ALEN);
    tt_response->flags = BATADV_TT_RESPONSE;

    if (full_table)
        tt_response->flags |= BATADV_TT_FULL_TABLE;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Sending TT_RESPONSE %pM via %pM for %pM (ttvn: %u)\n",
           res_dst_orig_node->orig, neigh_node->addr,
           req_dst_orig_node->orig, req_ttvn);

    batadv_inc_counter(bat_priv, BATADV_CNT_TT_RESPONSE_TX);

    batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
    ret = true;
    goto out;

unlock:
    spin_unlock_bh(&req_dst_orig_node->tt_buff_lock);

out:
    if (res_dst_orig_node)
        batadv_orig_node_free_ref(res_dst_orig_node);
    if (req_dst_orig_node)
        batadv_orig_node_free_ref(req_dst_orig_node);
    if (neigh_node)
        batadv_neigh_node_free_ref(neigh_node);
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    if (!ret)
        kfree_skb(skb);
    return ret;

}

static bool
batadv_send_my_tt_response(struct batadv_priv *bat_priv,
               struct batadv_tt_query_packet *tt_request)
{
    struct batadv_orig_node *orig_node = NULL;
    struct batadv_neigh_node *neigh_node = NULL;
    struct batadv_hard_iface *primary_if = NULL;
    uint8_t my_ttvn, req_ttvn, ttvn;
    int ret = false;
    unsigned char *tt_buff;
    bool full_table;
    uint16_t tt_len, tt_tot;
    struct sk_buff *skb = NULL;
    struct batadv_tt_query_packet *tt_response;
    uint8_t *packet_pos;
    size_t len;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Received TT_REQUEST from %pM for ttvn: %u (me) [%c]\n",
           tt_request->src, tt_request->ttvn,
           (tt_request->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));


    my_ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);
    req_ttvn = tt_request->ttvn;

    orig_node = batadv_orig_hash_find(bat_priv, tt_request->src);
    if (!orig_node)
        goto out;

    neigh_node = batadv_orig_node_get_router(orig_node);
    if (!neigh_node)
        goto out;

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

    /* If the full table has been explicitly requested or the gap
     * is too big send the whole local translation table
     */
    if (tt_request->flags & BATADV_TT_FULL_TABLE || my_ttvn != req_ttvn ||
        !bat_priv->tt.last_changeset)
        full_table = true;
    else
        full_table = false;

    /* In this version, fragmentation is not implemented, then
     * I'll send only one packet with as much TT entries as I can
     */
    if (!full_table) {
        spin_lock_bh(&bat_priv->tt.last_changeset_lock);
        tt_len = bat_priv->tt.last_changeset_len;
        tt_tot = tt_len / sizeof(struct batadv_tt_change);

        len = sizeof(*tt_response) + tt_len;
        skb = dev_alloc_skb(len + ETH_HLEN);
        if (!skb)
            goto unlock;

        skb_reserve(skb, ETH_HLEN);
        packet_pos = skb_put(skb, len);
        tt_response = (struct batadv_tt_query_packet *)packet_pos;
        tt_response->ttvn = req_ttvn;
        tt_response->tt_data = htons(tt_tot);

        tt_buff = skb->data + sizeof(*tt_response);
        memcpy(tt_buff, bat_priv->tt.last_changeset,
               bat_priv->tt.last_changeset_len);
        spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
    } else {
        tt_len = (uint16_t)atomic_read(&bat_priv->tt.local_entry_num);
        tt_len *= sizeof(struct batadv_tt_change);
        ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);

        skb = batadv_tt_response_fill_table(tt_len, ttvn,
                            bat_priv->tt.local_hash,
                            primary_if,
                            batadv_tt_local_valid_entry,
                            NULL);
        if (!skb)
            goto out;

        tt_response = (struct batadv_tt_query_packet *)skb->data;
    }

    tt_response->header.packet_type = BATADV_TT_QUERY;
    tt_response->header.version = BATADV_COMPAT_VERSION;
    tt_response->header.ttl = BATADV_TTL;
    memcpy(tt_response->src, primary_if->net_dev->dev_addr, ETH_ALEN);
    memcpy(tt_response->dst, tt_request->src, ETH_ALEN);
    tt_response->flags = BATADV_TT_RESPONSE;

    if (full_table)
        tt_response->flags |= BATADV_TT_FULL_TABLE;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Sending TT_RESPONSE to %pM via %pM [%c]\n",
           orig_node->orig, neigh_node->addr,
           (tt_response->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

    batadv_inc_counter(bat_priv, BATADV_CNT_TT_RESPONSE_TX);

    batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
    ret = true;
    goto out;

unlock:
    spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
out:
    if (orig_node)
        batadv_orig_node_free_ref(orig_node);
    if (neigh_node)
        batadv_neigh_node_free_ref(neigh_node);
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    if (!ret)
        kfree_skb(skb);
    /* This packet was for me, so it doesn't need to be re-routed */
    return true;
}

bool batadv_send_tt_response(struct batadv_priv *bat_priv,
                 struct batadv_tt_query_packet *tt_request)
{
    if (batadv_is_my_mac(tt_request->dst)) {
        /* don't answer backbone gws! */
        if (batadv_bla_is_backbone_gw_orig(bat_priv, tt_request->src))
            return true;

        return batadv_send_my_tt_response(bat_priv, tt_request);
    } else {
        return batadv_send_other_tt_response(bat_priv, tt_request);
    }
}

static void _batadv_tt_update_changes(struct batadv_priv *bat_priv,
                      struct batadv_orig_node *orig_node,
                      struct batadv_tt_change *tt_change,
                      uint16_t tt_num_changes, uint8_t ttvn)
{
    int i;
    int roams;

    for (i = 0; i < tt_num_changes; i++) {
        if ((tt_change + i)->flags & BATADV_TT_CLIENT_DEL) {
            roams = (tt_change + i)->flags & BATADV_TT_CLIENT_ROAM;
            batadv_tt_global_del(bat_priv, orig_node,
                         (tt_change + i)->addr,
                         "tt removed by changes",
                         roams);
        } else {
            if (!batadv_tt_global_add(bat_priv, orig_node,
                          (tt_change + i)->addr,
                          (tt_change + i)->flags, ttvn))
                /* In case of problem while storing a
                 * global_entry, we stop the updating
                 * procedure without committing the
                 * ttvn change. This will avoid to send
                 * corrupted data on tt_request
                 */
                return;
        }
    }
    orig_node->tt_initialised = true;
}

static void batadv_tt_fill_gtable(struct batadv_priv *bat_priv,
                  struct batadv_tt_query_packet *tt_response)
{
    struct batadv_orig_node *orig_node = NULL;

    orig_node = batadv_orig_hash_find(bat_priv, tt_response->src);
    if (!orig_node)
        goto out;

    /* Purge the old table first.. */
    batadv_tt_global_del_orig(bat_priv, orig_node, "Received full table");

    _batadv_tt_update_changes(bat_priv, orig_node,
                  (struct batadv_tt_change *)(tt_response + 1),
                  ntohs(tt_response->tt_data),
                  tt_response->ttvn);

    spin_lock_bh(&orig_node->tt_buff_lock);
    kfree(orig_node->tt_buff);
    orig_node->tt_buff_len = 0;
    orig_node->tt_buff = NULL;
    spin_unlock_bh(&orig_node->tt_buff_lock);

    atomic_set(&orig_node->last_ttvn, tt_response->ttvn);

out:
    if (orig_node)
        batadv_orig_node_free_ref(orig_node);
}

static void batadv_tt_update_changes(struct batadv_priv *bat_priv,
                     struct batadv_orig_node *orig_node,
                     uint16_t tt_num_changes, uint8_t ttvn,
                     struct batadv_tt_change *tt_change)
{
    _batadv_tt_update_changes(bat_priv, orig_node, tt_change,
                  tt_num_changes, ttvn);

    batadv_tt_save_orig_buffer(bat_priv, orig_node,
                   (unsigned char *)tt_change, tt_num_changes);
    atomic_set(&orig_node->last_ttvn, ttvn);
}

bool batadv_is_my_client(struct batadv_priv *bat_priv, const uint8_t *addr)
{
    struct batadv_tt_local_entry *tt_local_entry = NULL;
    bool ret = false;

    tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);
    if (!tt_local_entry)
        goto out;
    /* Check if the client has been logically deleted (but is kept for
     * consistency purpose)
     */
    if (tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING)
        goto out;
    ret = true;
out:
    if (tt_local_entry)
        batadv_tt_local_entry_free_ref(tt_local_entry);
    return ret;
}

void batadv_handle_tt_response(struct batadv_priv *bat_priv,
                   struct batadv_tt_query_packet *tt_response)
{
    struct batadv_tt_req_node *node, *safe;
    struct batadv_orig_node *orig_node = NULL;
    struct batadv_tt_change *tt_change;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Received TT_RESPONSE from %pM for ttvn %d t_size: %d [%c]\n",
           tt_response->src, tt_response->ttvn,
           ntohs(tt_response->tt_data),
           (tt_response->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

    /* we should have never asked a backbone gw */
    if (batadv_bla_is_backbone_gw_orig(bat_priv, tt_response->src))
        goto out;

    orig_node = batadv_orig_hash_find(bat_priv, tt_response->src);
    if (!orig_node)
        goto out;

    if (tt_response->flags & BATADV_TT_FULL_TABLE) {
        batadv_tt_fill_gtable(bat_priv, tt_response);
    } else {
        tt_change = (struct batadv_tt_change *)(tt_response + 1);
        batadv_tt_update_changes(bat_priv, orig_node,
                     ntohs(tt_response->tt_data),
                     tt_response->ttvn, tt_change);
    }

    /* Delete the tt_req_node from pending tt_requests list */
    spin_lock_bh(&bat_priv->tt.req_list_lock);
    list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
        if (!batadv_compare_eth(node->addr, tt_response->src))
            continue;
        list_del(&node->list);
        kfree(node);
    }
    spin_unlock_bh(&bat_priv->tt.req_list_lock);

    /* Recalculate the CRC for this orig_node and store it */
    orig_node->tt_crc = batadv_tt_global_crc(bat_priv, orig_node);
    /* Roaming phase is over: tables are in sync again. I can
     * unset the flag
     */
    orig_node->tt_poss_change = false;
out:
    if (orig_node)
        batadv_orig_node_free_ref(orig_node);
}

int batadv_tt_init(struct batadv_priv *bat_priv)
{
    int ret;

    ret = batadv_tt_local_init(bat_priv);
    if (ret < 0)
        return ret;

    ret = batadv_tt_global_init(bat_priv);
    if (ret < 0)
        return ret;

    batadv_tt_start_timer(bat_priv);

    return 1;
}

static void batadv_tt_roam_list_free(struct batadv_priv *bat_priv)
{
    struct batadv_tt_roam_node *node, *safe;

    spin_lock_bh(&bat_priv->tt.roam_list_lock);

    list_for_each_entry_safe(node, safe, &bat_priv->tt.roam_list, list) {
        list_del(&node->list);
        kfree(node);
    }

    spin_unlock_bh(&bat_priv->tt.roam_list_lock);
}

static void batadv_tt_roam_purge(struct batadv_priv *bat_priv)
{
    struct batadv_tt_roam_node *node, *safe;

    spin_lock_bh(&bat_priv->tt.roam_list_lock);
    list_for_each_entry_safe(node, safe, &bat_priv->tt.roam_list, list) {
        if (!batadv_has_timed_out(node->first_time,
                      BATADV_ROAMING_MAX_TIME))
            continue;

        list_del(&node->list);
        kfree(node);
    }
    spin_unlock_bh(&bat_priv->tt.roam_list_lock);
}

/* This function checks whether the client already reached the
 * maximum number of possible roaming phases. In this case the ROAMING_ADV
 * will not be sent.
 *
 * returns true if the ROAMING_ADV can be sent, false otherwise
 */
static bool batadv_tt_check_roam_count(struct batadv_priv *bat_priv,
                       uint8_t *client)
{
    struct batadv_tt_roam_node *tt_roam_node;
    bool ret = false;

    spin_lock_bh(&bat_priv->tt.roam_list_lock);
    /* The new tt_req will be issued only if I'm not waiting for a
     * reply from the same orig_node yet
     */
    list_for_each_entry(tt_roam_node, &bat_priv->tt.roam_list, list) {
        if (!batadv_compare_eth(tt_roam_node->addr, client))
            continue;

        if (batadv_has_timed_out(tt_roam_node->first_time,
                     BATADV_ROAMING_MAX_TIME))
            continue;

        if (!batadv_atomic_dec_not_zero(&tt_roam_node->counter))
            /* Sorry, you roamed too many times! */
            goto unlock;
        ret = true;
        break;
    }

    if (!ret) {
        tt_roam_node = kmalloc(sizeof(*tt_roam_node), GFP_ATOMIC);
        if (!tt_roam_node)
            goto unlock;

        tt_roam_node->first_time = jiffies;
        atomic_set(&tt_roam_node->counter,
               BATADV_ROAMING_MAX_COUNT - 1);
        memcpy(tt_roam_node->addr, client, ETH_ALEN);

        list_add(&tt_roam_node->list, &bat_priv->tt.roam_list);
        ret = true;
    }

unlock:
    spin_unlock_bh(&bat_priv->tt.roam_list_lock);
    return ret;
}

static void batadv_send_roam_adv(struct batadv_priv *bat_priv, uint8_t *client,
                 struct batadv_orig_node *orig_node)
{
    struct batadv_neigh_node *neigh_node = NULL;
    struct sk_buff *skb = NULL;
    struct batadv_roam_adv_packet *roam_adv_packet;
    int ret = 1;
    struct batadv_hard_iface *primary_if;
    size_t len = sizeof(*roam_adv_packet);

    /* before going on we have to check whether the client has
     * already roamed to us too many times
     */
    if (!batadv_tt_check_roam_count(bat_priv, client))
        goto out;

    skb = dev_alloc_skb(sizeof(*roam_adv_packet) + ETH_HLEN);
    if (!skb)
        goto out;

    skb_reserve(skb, ETH_HLEN);

    roam_adv_packet = (struct batadv_roam_adv_packet *)skb_put(skb, len);

    roam_adv_packet->header.packet_type = BATADV_ROAM_ADV;
    roam_adv_packet->header.version = BATADV_COMPAT_VERSION;
    roam_adv_packet->header.ttl = BATADV_TTL;
    roam_adv_packet->reserved = 0;
    primary_if = batadv_primary_if_get_selected(bat_priv);
    if (!primary_if)
        goto out;
    memcpy(roam_adv_packet->src, primary_if->net_dev->dev_addr, ETH_ALEN);
    batadv_hardif_free_ref(primary_if);
    memcpy(roam_adv_packet->dst, orig_node->orig, ETH_ALEN);
    memcpy(roam_adv_packet->client, client, ETH_ALEN);

    neigh_node = batadv_orig_node_get_router(orig_node);
    if (!neigh_node)
        goto out;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Sending ROAMING_ADV to %pM (client %pM) via %pM\n",
           orig_node->orig, client, neigh_node->addr);

    batadv_inc_counter(bat_priv, BATADV_CNT_TT_ROAM_ADV_TX);

    batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
    ret = 0;

out:
    if (neigh_node)
        batadv_neigh_node_free_ref(neigh_node);
    if (ret)
        kfree_skb(skb);
    return;
}

static void batadv_tt_purge(struct work_struct *work)
{
    struct delayed_work *delayed_work;
    struct batadv_priv_tt *priv_tt;
    struct batadv_priv *bat_priv;

    delayed_work = container_of(work, struct delayed_work, work);
    priv_tt = container_of(delayed_work, struct batadv_priv_tt, work);
    bat_priv = container_of(priv_tt, struct batadv_priv, tt);

    batadv_tt_local_purge(bat_priv);
    batadv_tt_global_purge(bat_priv);
    batadv_tt_req_purge(bat_priv);
    batadv_tt_roam_purge(bat_priv);

    batadv_tt_start_timer(bat_priv);
}

void batadv_tt_free(struct batadv_priv *bat_priv)
{
    cancel_delayed_work_sync(&bat_priv->tt.work);

    batadv_tt_local_table_free(bat_priv);
    batadv_tt_global_table_free(bat_priv);
    batadv_tt_req_list_free(bat_priv);
    batadv_tt_changes_list_free(bat_priv);
    batadv_tt_roam_list_free(bat_priv);

    kfree(bat_priv->tt.last_changeset);
}

/* This function will enable or disable the specified flags for all the entries
 * in the given hash table and returns the number of modified entries
 */
static uint16_t batadv_tt_set_flags(struct batadv_hashtable *hash,
                    uint16_t flags, bool enable)
{
    uint32_t i;
    uint16_t changed_num = 0;
    struct hlist_head *head;
    struct hlist_node *node;
    struct batadv_tt_common_entry *tt_common_entry;

    if (!hash)
        goto out;

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common_entry, node,
                     head, hash_entry) {
            if (enable) {
                if ((tt_common_entry->flags & flags) == flags)
                    continue;
                tt_common_entry->flags |= flags;
            } else {
                if (!(tt_common_entry->flags & flags))
                    continue;
                tt_common_entry->flags &= ~flags;
            }
            changed_num++;
        }
        rcu_read_unlock();
    }
out:
    return changed_num;
}

/* Purge out all the tt local entries marked with BATADV_TT_CLIENT_PENDING */
static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
{
    struct batadv_hashtable *hash = bat_priv->tt.local_hash;
    struct batadv_tt_common_entry *tt_common;
    struct batadv_tt_local_entry *tt_local;
    struct hlist_node *node, *node_tmp;
    struct hlist_head *head;
    spinlock_t *list_lock; /* protects write access to the hash lists */
    uint32_t i;

    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(tt_common, node, node_tmp, head,
                      hash_entry) {
            if (!(tt_common->flags & BATADV_TT_CLIENT_PENDING))
                continue;

            batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Deleting local tt entry (%pM): pending\n",
                   tt_common->addr);

            atomic_dec(&bat_priv->tt.local_entry_num);
            hlist_del_rcu(node);
            tt_local = container_of(tt_common,
                        struct batadv_tt_local_entry,
                        common);
            batadv_tt_local_entry_free_ref(tt_local);
        }
        spin_unlock_bh(list_lock);
    }

}

static int batadv_tt_commit_changes(struct batadv_priv *bat_priv,
                    unsigned char **packet_buff,
                    int *packet_buff_len, int packet_min_len)
{
    uint16_t changed_num = 0;

    if (atomic_read(&bat_priv->tt.local_changes) < 1)
        return -ENOENT;

    changed_num = batadv_tt_set_flags(bat_priv->tt.local_hash,
                      BATADV_TT_CLIENT_NEW, false);

    /* all reset entries have to be counted as local entries */
    atomic_add(changed_num, &bat_priv->tt.local_entry_num);
    batadv_tt_local_purge_pending_clients(bat_priv);
    bat_priv->tt.local_crc = batadv_tt_local_crc(bat_priv);

    /* Increment the TTVN only once per OGM interval */
    atomic_inc(&bat_priv->tt.vn);
    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Local changes committed, updating to ttvn %u\n",
           (uint8_t)atomic_read(&bat_priv->tt.vn));
    bat_priv->tt.poss_change = false;

    /* reset the sending counter */
    atomic_set(&bat_priv->tt.ogm_append_cnt, BATADV_TT_OGM_APPEND_MAX);

    return batadv_tt_changes_fill_buff(bat_priv, packet_buff,
                       packet_buff_len, packet_min_len);
}

/* when calling this function (hard_iface == primary_if) has to be true */
int batadv_tt_append_diff(struct batadv_priv *bat_priv,
              unsigned char **packet_buff, int *packet_buff_len,
              int packet_min_len)
{
    int tt_num_changes;

    /* if at least one change happened */
    tt_num_changes = batadv_tt_commit_changes(bat_priv, packet_buff,
                          packet_buff_len,
                          packet_min_len);

    /* if the changes have been sent often enough */
    if ((tt_num_changes < 0) &&
        (!batadv_atomic_dec_not_zero(&bat_priv->tt.ogm_append_cnt))) {
        batadv_tt_realloc_packet_buff(packet_buff, packet_buff_len,
                          packet_min_len, packet_min_len);
        tt_num_changes = 0;
    }

    return tt_num_changes;
}

bool batadv_is_ap_isolated(struct batadv_priv *bat_priv, uint8_t *src,
               uint8_t *dst)
{
    struct batadv_tt_local_entry *tt_local_entry = NULL;
    struct batadv_tt_global_entry *tt_global_entry = NULL;
    bool ret = false;

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

    tt_local_entry = batadv_tt_local_hash_find(bat_priv, dst);
    if (!tt_local_entry)
        goto out;

    tt_global_entry = batadv_tt_global_hash_find(bat_priv, src);
    if (!tt_global_entry)
        goto out;

    if (!_batadv_is_ap_isolated(tt_local_entry, tt_global_entry))
        goto out;

    ret = true;

out:
    if (tt_global_entry)
        batadv_tt_global_entry_free_ref(tt_global_entry);
    if (tt_local_entry)
        batadv_tt_local_entry_free_ref(tt_local_entry);
    return ret;
}

void batadv_tt_update_orig(struct batadv_priv *bat_priv,
               struct batadv_orig_node *orig_node,
               const unsigned char *tt_buff, uint8_t tt_num_changes,
               uint8_t ttvn, uint16_t tt_crc)
{
    uint8_t orig_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
    bool full_table = true;
    struct batadv_tt_change *tt_change;

    /* don't care about a backbone gateways updates. */
    if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig))
        return;

    /* orig table not initialised AND first diff is in the OGM OR the ttvn
     * increased by one -> we can apply the attached changes
     */
    if ((!orig_node->tt_initialised && ttvn == 1) ||
        ttvn - orig_ttvn == 1) {
        /* the OGM could not contain the changes due to their size or
         * because they have already been sent BATADV_TT_OGM_APPEND_MAX
         * times.
         * In this case send a tt request
         */
        if (!tt_num_changes) {
            full_table = false;
            goto request_table;
        }

        tt_change = (struct batadv_tt_change *)tt_buff;
        batadv_tt_update_changes(bat_priv, orig_node, tt_num_changes,
                     ttvn, tt_change);

        /* Even if we received the precomputed crc with the OGM, we
         * prefer to recompute it to spot any possible inconsistency
         * in the global table
         */
        orig_node->tt_crc = batadv_tt_global_crc(bat_priv, orig_node);

        /* The ttvn alone is not enough to guarantee consistency
         * because a single value could represent different states
         * (due to the wrap around). Thus a node has to check whether
         * the resulting table (after applying the changes) is still
         * consistent or not. E.g. a node could disconnect while its
         * ttvn is X and reconnect on ttvn = X + TTVN_MAX: in this case
         * checking the CRC value is mandatory to detect the
         * inconsistency
         */
        if (orig_node->tt_crc != tt_crc)
            goto request_table;

        /* Roaming phase is over: tables are in sync again. I can
         * unset the flag
         */
        orig_node->tt_poss_change = false;
    } else {
        /* if we missed more than one change or our tables are not
         * in sync anymore -> request fresh tt data
         */
        if (!orig_node->tt_initialised || ttvn != orig_ttvn ||
            orig_node->tt_crc != tt_crc) {
request_table:
            batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "TT inconsistency for %pM. Need to retrieve the correct information (ttvn: %u last_ttvn: %u crc: %u last_crc: %u num_changes: %u)\n",
                   orig_node->orig, ttvn, orig_ttvn, tt_crc,
                   orig_node->tt_crc, tt_num_changes);
            batadv_send_tt_request(bat_priv, orig_node, ttvn,
                           tt_crc, full_table);
            return;
        }
    }
}

/* returns true whether we know that the client has moved from its old
 * originator to another one. This entry is kept is still kept for consistency
 * purposes
 */
bool batadv_tt_global_client_is_roaming(struct batadv_priv *bat_priv,
                    uint8_t *addr)
{
    struct batadv_tt_global_entry *tt_global_entry;
    bool ret = false;

    tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
    if (!tt_global_entry)
        goto out;

    ret = tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM;
    batadv_tt_global_entry_free_ref(tt_global_entry);
out:
    return ret;
}

bool batadv_tt_add_temporary_global_entry(struct batadv_priv *bat_priv,
                      struct batadv_orig_node *orig_node,
                      const unsigned char *addr)
{
    bool ret = false;

    /* if the originator is a backbone node (meaning it belongs to the same
     * LAN of this node) the temporary client must not be added because to
     * reach such destination the node must use the LAN instead of the mesh
     */
    if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig))
        goto out;

    if (!batadv_tt_global_add(bat_priv, orig_node, addr,
                  BATADV_TT_CLIENT_TEMP,
                  atomic_read(&orig_node->last_ttvn)))
        goto out;

    batadv_dbg(BATADV_DBG_TT, bat_priv,
           "Added temporary global client (addr: %pM orig: %pM)\n",
           addr, orig_node->orig);
    ret = true;
out:
    return ret;
}