/* Copyright (C) 2008-2013 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

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

#define BATADV_MAX_VIS_PACKET_SIZE 1000

/* hash class keys */
static struct lock_class_key batadv_vis_hash_lock_class_key;

/* free the info */
static void batadv_free_info(struct kref *ref)
{
        struct batadv_vis_info *info;
        struct batadv_priv *bat_priv;
        struct batadv_vis_recvlist_node *entry, *tmp;

        info = container_of(ref, struct batadv_vis_info, refcount);
        bat_priv = info->bat_priv;

        list_del_init(&info->send_list);
        spin_lock_bh(&bat_priv->vis.list_lock);
        list_for_each_entry_safe(entry, tmp, &info->recv_list, list) {
                list_del(&entry->list);
                kfree(entry);
        }

        spin_unlock_bh(&bat_priv->vis.list_lock);
        kfree_skb(info->skb_packet);
        kfree(info);
}

/* Compare two vis packets, used by the hashing algorithm */
static int batadv_vis_info_cmp(const struct hlist_node *node, const void *data2)
{
        const struct batadv_vis_info *d1, *d2;
        const struct batadv_vis_packet *p1, *p2;

        d1 = container_of(node, struct batadv_vis_info, hash_entry);
        d2 = data2;
        p1 = (struct batadv_vis_packet *)d1->skb_packet->data;
        p2 = (struct batadv_vis_packet *)d2->skb_packet->data;
        return batadv_compare_eth(p1->vis_orig, p2->vis_orig);
}

/* hash function to choose an entry in a hash table of given size
 * hash algorithm from http://en.wikipedia.org/wiki/Hash_table
 */
static uint32_t batadv_vis_info_choose(const void *data, uint32_t size)
{
        const struct batadv_vis_info *vis_info = data;
        const struct batadv_vis_packet *packet;
        const unsigned char *key;
        uint32_t hash = 0;
        size_t i;

        packet = (struct batadv_vis_packet *)vis_info->skb_packet->data;
        key = packet->vis_orig;
        for (i = 0; i < ETH_ALEN; i++) {
                hash += key[i];
                hash += (hash << 10);
                hash ^= (hash >> 6);
        }

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

        return hash % size;
}

static struct batadv_vis_info *
batadv_vis_hash_find(struct batadv_priv *bat_priv, const void *data)
{
        struct batadv_hashtable *hash = bat_priv->vis.hash;
        struct hlist_head *head;
        struct batadv_vis_info *vis_info, *vis_info_tmp = NULL;
        uint32_t index;

        if (!hash)
                return NULL;

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(vis_info, head, hash_entry) {
                if (!batadv_vis_info_cmp(&vis_info->hash_entry, data))
                        continue;

                vis_info_tmp = vis_info;
                break;
        }
        rcu_read_unlock();

        return vis_info_tmp;
}

/* insert interface to the list of interfaces of one originator, if it
 * does not already exist in the list
 */
static void batadv_vis_data_insert_interface(const uint8_t *interface,
                                             struct hlist_head *if_list,
                                             bool primary)
{
        struct batadv_vis_if_list_entry *entry;

        hlist_for_each_entry(entry, if_list, list) {
                if (batadv_compare_eth(entry->addr, interface))
                        return;
        }

        /* it's a new address, add it to the list */
        entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
        if (!entry)
                return;
        memcpy(entry->addr, interface, ETH_ALEN);
        entry->primary = primary;
        hlist_add_head(&entry->list, if_list);
}

static void batadv_vis_data_read_prim_sec(struct seq_file *seq,
                                          const struct hlist_head *if_list)
{
        struct batadv_vis_if_list_entry *entry;

        hlist_for_each_entry(entry, if_list, list) {
                if (entry->primary)
                        seq_puts(seq, "PRIMARY, ");
                else
                        seq_printf(seq,  "SEC %pM, ", entry->addr);
        }
}

/* read an entry  */
static ssize_t
batadv_vis_data_read_entry(struct seq_file *seq,
                           const struct batadv_vis_info_entry *entry,
                           const uint8_t *src, bool primary)
{
        if (primary && entry->quality == 0)
                return seq_printf(seq, "TT %pM, ", entry->dest);
        else if (batadv_compare_eth(entry->src, src))
                return seq_printf(seq, "TQ %pM %d, ", entry->dest,
                                  entry->quality);

        return 0;
}

static void
batadv_vis_data_insert_interfaces(struct hlist_head *list,
                                  struct batadv_vis_packet *packet,
                                  struct batadv_vis_info_entry *entries)
{
        int i;

        for (i = 0; i < packet->entries; i++) {
                if (entries[i].quality == 0)
                        continue;

                if (batadv_compare_eth(entries[i].src, packet->vis_orig))
                        continue;

                batadv_vis_data_insert_interface(entries[i].src, list, false);
        }
}

static void batadv_vis_data_read_entries(struct seq_file *seq,
                                         struct hlist_head *list,
                                         struct batadv_vis_packet *packet,
                                         struct batadv_vis_info_entry *entries)
{
        int i;
        struct batadv_vis_if_list_entry *entry;

        hlist_for_each_entry(entry, list, list) {
                seq_printf(seq, "%pM,", entry->addr);

                for (i = 0; i < packet->entries; i++)
                        batadv_vis_data_read_entry(seq, &entries[i],
                                                   entry->addr, entry->primary);

                /* add primary/secondary records */
                if (batadv_compare_eth(entry->addr, packet->vis_orig))
                        batadv_vis_data_read_prim_sec(seq, list);

                seq_puts(seq, "\n");
        }
}

static void batadv_vis_seq_print_text_bucket(struct seq_file *seq,
                                             const struct hlist_head *head)
{
        struct batadv_vis_info *info;
        struct batadv_vis_packet *packet;
        uint8_t *entries_pos;
        struct batadv_vis_info_entry *entries;
        struct batadv_vis_if_list_entry *entry;
        struct hlist_node *n;

        HLIST_HEAD(vis_if_list);

        hlist_for_each_entry_rcu(info, head, hash_entry) {
                packet = (struct batadv_vis_packet *)info->skb_packet->data;
                entries_pos = (uint8_t *)packet + sizeof(*packet);
                entries = (struct batadv_vis_info_entry *)entries_pos;

                batadv_vis_data_insert_interface(packet->vis_orig, &vis_if_list,
                                                 true);
                batadv_vis_data_insert_interfaces(&vis_if_list, packet,
                                                  entries);
                batadv_vis_data_read_entries(seq, &vis_if_list, packet,
                                             entries);

                hlist_for_each_entry_safe(entry, n, &vis_if_list, list) {
                        hlist_del(&entry->list);
                        kfree(entry);
                }
        }
}

int batadv_vis_seq_print_text(struct seq_file *seq, void *offset)
{
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        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->vis.hash;
        uint32_t i;
        int ret = 0;
        int vis_server = atomic_read(&bat_priv->vis_mode);

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

        if (vis_server == BATADV_VIS_TYPE_CLIENT_UPDATE)
                goto out;

        spin_lock_bh(&bat_priv->vis.hash_lock);
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];
                batadv_vis_seq_print_text_bucket(seq, head);
        }
        spin_unlock_bh(&bat_priv->vis.hash_lock);

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

/* add the info packet to the send list, if it was not
 * already linked in.
 */
static void batadv_send_list_add(struct batadv_priv *bat_priv,
                                 struct batadv_vis_info *info)
{
        if (list_empty(&info->send_list)) {
                kref_get(&info->refcount);
                list_add_tail(&info->send_list, &bat_priv->vis.send_list);
        }
}

/* delete the info packet from the send list, if it was
 * linked in.
 */
static void batadv_send_list_del(struct batadv_vis_info *info)
{
        if (!list_empty(&info->send_list)) {
                list_del_init(&info->send_list);
                kref_put(&info->refcount, batadv_free_info);
        }
}

/* tries to add one entry to the receive list. */
static void batadv_recv_list_add(struct batadv_priv *bat_priv,
                                 struct list_head *recv_list, const char *mac)
{
        struct batadv_vis_recvlist_node *entry;

        entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
        if (!entry)
                return;

        memcpy(entry->mac, mac, ETH_ALEN);
        spin_lock_bh(&bat_priv->vis.list_lock);
        list_add_tail(&entry->list, recv_list);
        spin_unlock_bh(&bat_priv->vis.list_lock);
}

/* returns 1 if this mac is in the recv_list */
static int batadv_recv_list_is_in(struct batadv_priv *bat_priv,
                                  const struct list_head *recv_list,
                                  const char *mac)
{
        const struct batadv_vis_recvlist_node *entry;

        spin_lock_bh(&bat_priv->vis.list_lock);
        list_for_each_entry(entry, recv_list, list) {
                if (batadv_compare_eth(entry->mac, mac)) {
                        spin_unlock_bh(&bat_priv->vis.list_lock);
                        return 1;
                }
        }
        spin_unlock_bh(&bat_priv->vis.list_lock);
        return 0;
}

/* try to add the packet to the vis_hash. return NULL if invalid (e.g. too old,
 * broken.. ).  vis hash must be locked outside.  is_new is set when the packet
 * is newer than old entries in the hash.
 */
static struct batadv_vis_info *
batadv_add_packet(struct batadv_priv *bat_priv,
                  struct batadv_vis_packet *vis_packet, int vis_info_len,
                  int *is_new, int make_broadcast)
{
        struct batadv_vis_info *info, *old_info;
        struct batadv_vis_packet *search_packet, *old_packet;
        struct batadv_vis_info search_elem;
        struct batadv_vis_packet *packet;
        struct sk_buff *tmp_skb;
        int hash_added;
        size_t len;
        size_t max_entries;

        *is_new = 0;
        /* sanity check */
        if (!bat_priv->vis.hash)
                return NULL;

        /* see if the packet is already in vis_hash */
        search_elem.skb_packet = dev_alloc_skb(sizeof(*search_packet));
        if (!search_elem.skb_packet)
                return NULL;
        len = sizeof(*search_packet);
        tmp_skb = search_elem.skb_packet;
        search_packet = (struct batadv_vis_packet *)skb_put(tmp_skb, len);

        memcpy(search_packet->vis_orig, vis_packet->vis_orig, ETH_ALEN);
        old_info = batadv_vis_hash_find(bat_priv, &search_elem);
        kfree_skb(search_elem.skb_packet);

        if (old_info) {
                tmp_skb = old_info->skb_packet;
                old_packet = (struct batadv_vis_packet *)tmp_skb->data;
                if (!batadv_seq_after(ntohl(vis_packet->seqno),
                                      ntohl(old_packet->seqno))) {
                        if (old_packet->seqno == vis_packet->seqno) {
                                batadv_recv_list_add(bat_priv,
                                                     &old_info->recv_list,
                                                     vis_packet->sender_orig);
                                return old_info;
                        } else {
                                /* newer packet is already in hash. */
                                return NULL;
                        }
                }
                /* remove old entry */
                batadv_hash_remove(bat_priv->vis.hash, batadv_vis_info_cmp,
                                   batadv_vis_info_choose, old_info);
                batadv_send_list_del(old_info);
                kref_put(&old_info->refcount, batadv_free_info);
        }

        info = kmalloc(sizeof(*info), GFP_ATOMIC);
        if (!info)
                return NULL;

        len = sizeof(*packet) + vis_info_len;
        info->skb_packet = dev_alloc_skb(len + ETH_HLEN + NET_IP_ALIGN);
        if (!info->skb_packet) {
                kfree(info);
                return NULL;
        }
        skb_reserve(info->skb_packet, ETH_HLEN + NET_IP_ALIGN);
        packet = (struct batadv_vis_packet *)skb_put(info->skb_packet, len);

        kref_init(&info->refcount);
        INIT_LIST_HEAD(&info->send_list);
        INIT_LIST_HEAD(&info->recv_list);
        info->first_seen = jiffies;
        info->bat_priv = bat_priv;
        memcpy(packet, vis_packet, len);

        /* initialize and add new packet. */
        *is_new = 1;

        /* Make it a broadcast packet, if required */
        if (make_broadcast)
                memcpy(packet->target_orig, batadv_broadcast_addr, ETH_ALEN);

        /* repair if entries is longer than packet. */
        max_entries = vis_info_len / sizeof(struct batadv_vis_info_entry);
        if (packet->entries > max_entries)
                packet->entries = max_entries;

        batadv_recv_list_add(bat_priv, &info->recv_list, packet->sender_orig);

        /* try to add it */
        hash_added = batadv_hash_add(bat_priv->vis.hash, batadv_vis_info_cmp,
                                     batadv_vis_info_choose, info,
                                     &info->hash_entry);
        if (hash_added != 0) {
                /* did not work (for some reason) */
                kref_put(&info->refcount, batadv_free_info);
                info = NULL;
        }

        return info;
}

/* handle the server sync packet, forward if needed. */
void batadv_receive_server_sync_packet(struct batadv_priv *bat_priv,
                                       struct batadv_vis_packet *vis_packet,
                                       int vis_info_len)
{
        struct batadv_vis_info *info;
        int is_new, make_broadcast;
        int vis_server = atomic_read(&bat_priv->vis_mode);

        make_broadcast = (vis_server == BATADV_VIS_TYPE_SERVER_SYNC);

        spin_lock_bh(&bat_priv->vis.hash_lock);
        info = batadv_add_packet(bat_priv, vis_packet, vis_info_len,
                                 &is_new, make_broadcast);
        if (!info)
                goto end;

        /* only if we are server ourselves and packet is newer than the one in
         * hash.
         */
        if (vis_server == BATADV_VIS_TYPE_SERVER_SYNC && is_new)
                batadv_send_list_add(bat_priv, info);
end:
        spin_unlock_bh(&bat_priv->vis.hash_lock);
}

/* handle an incoming client update packet and schedule forward if needed. */
void batadv_receive_client_update_packet(struct batadv_priv *bat_priv,
                                         struct batadv_vis_packet *vis_packet,
                                         int vis_info_len)
{
        struct batadv_vis_info *info;
        struct batadv_vis_packet *packet;
        int is_new;
        int vis_server = atomic_read(&bat_priv->vis_mode);
        int are_target = 0;

        /* clients shall not broadcast. */
        if (is_broadcast_ether_addr(vis_packet->target_orig))
                return;

        /* Are we the target for this VIS packet? */
        if (vis_server == BATADV_VIS_TYPE_SERVER_SYNC   &&
            batadv_is_my_mac(bat_priv, vis_packet->target_orig))
                are_target = 1;

        spin_lock_bh(&bat_priv->vis.hash_lock);
        info = batadv_add_packet(bat_priv, vis_packet, vis_info_len,
                                 &is_new, are_target);

        if (!info)
                goto end;
        /* note that outdated packets will be dropped at this point. */

        packet = (struct batadv_vis_packet *)info->skb_packet->data;

        /* send only if we're the target server or ... */
        if (are_target && is_new) {
                packet->vis_type = BATADV_VIS_TYPE_SERVER_SYNC; /* upgrade! */
                batadv_send_list_add(bat_priv, info);

                /* ... we're not the recipient (and thus need to forward). */
        } else if (!batadv_is_my_mac(bat_priv, packet->target_orig)) {
                batadv_send_list_add(bat_priv, info);
        }

end:
        spin_unlock_bh(&bat_priv->vis.hash_lock);
}

/* Walk the originators and find the VIS server with the best tq. Set the packet
 * address to its address and return the best_tq.
 *
 * Must be called with the originator hash locked
 */
static int batadv_find_best_vis_server(struct batadv_priv *bat_priv,
                                       struct batadv_vis_info *info)
{
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct batadv_neigh_node *router;
        struct hlist_head *head;
        struct batadv_orig_node *orig_node;
        struct batadv_vis_packet *packet;
        int best_tq = -1;
        uint32_t i;

        packet = (struct batadv_vis_packet *)info->skb_packet->data;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        router = batadv_orig_node_get_router(orig_node);
                        if (!router)
                                continue;

                        if ((orig_node->flags & BATADV_VIS_SERVER) &&
                            (router->tq_avg > best_tq)) {
                                best_tq = router->tq_avg;
                                memcpy(packet->target_orig, orig_node->orig,
                                       ETH_ALEN);
                        }
                        batadv_neigh_node_free_ref(router);
                }
                rcu_read_unlock();
        }

        return best_tq;
}

/* Return true if the vis packet is full. */
static bool batadv_vis_packet_full(const struct batadv_vis_info *info)
{
        const struct batadv_vis_packet *packet;
        size_t num;

        packet = (struct batadv_vis_packet *)info->skb_packet->data;
        num = BATADV_MAX_VIS_PACKET_SIZE / sizeof(struct batadv_vis_info_entry);

        if (num < packet->entries + 1)
                return true;
        return false;
}

/* generates a packet of own vis data,
 * returns 0 on success, -1 if no packet could be generated
 */
static int batadv_generate_vis_packet(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct hlist_head *head;
        struct batadv_orig_node *orig_node;
        struct batadv_neigh_node *router;
        struct batadv_vis_info *info = bat_priv->vis.my_info;
        struct batadv_vis_packet *packet;
        struct batadv_vis_info_entry *entry;
        struct batadv_tt_common_entry *tt_common_entry;
        uint8_t *packet_pos;
        int best_tq = -1;
        uint32_t i;

        info->first_seen = jiffies;
        packet = (struct batadv_vis_packet *)info->skb_packet->data;
        packet->vis_type = atomic_read(&bat_priv->vis_mode);

        memcpy(packet->target_orig, batadv_broadcast_addr, ETH_ALEN);
        packet->header.ttl = BATADV_TTL;
        packet->seqno = htonl(ntohl(packet->seqno) + 1);
        packet->entries = 0;
        packet->reserved = 0;
        skb_trim(info->skb_packet, sizeof(*packet));

        if (packet->vis_type == BATADV_VIS_TYPE_CLIENT_UPDATE) {
                best_tq = batadv_find_best_vis_server(bat_priv, info);

                if (best_tq < 0)
                        return best_tq;
        }

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        router = batadv_orig_node_get_router(orig_node);
                        if (!router)
                                continue;

                        if (!batadv_compare_eth(router->addr, orig_node->orig))
                                goto next;

                        if (router->if_incoming->if_status != BATADV_IF_ACTIVE)
                                goto next;

                        if (router->tq_avg < 1)
                                goto next;

                        /* fill one entry into buffer. */
                        packet_pos = skb_put(info->skb_packet, sizeof(*entry));
                        entry = (struct batadv_vis_info_entry *)packet_pos;
                        memcpy(entry->src,
                               router->if_incoming->net_dev->dev_addr,
                               ETH_ALEN);
                        memcpy(entry->dest, orig_node->orig, ETH_ALEN);
                        entry->quality = router->tq_avg;
                        packet->entries++;

next:
                        batadv_neigh_node_free_ref(router);

                        if (batadv_vis_packet_full(info))
                                goto unlock;
                }
                rcu_read_unlock();
        }

        hash = bat_priv->tt.local_hash;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common_entry, head,
                                         hash_entry) {
                        packet_pos = skb_put(info->skb_packet, sizeof(*entry));
                        entry = (struct batadv_vis_info_entry *)packet_pos;
                        memset(entry->src, 0, ETH_ALEN);
                        memcpy(entry->dest, tt_common_entry->addr, ETH_ALEN);
                        entry->quality = 0; /* 0 means TT */
                        packet->entries++;

                        if (batadv_vis_packet_full(info))
                                goto unlock;
                }
                rcu_read_unlock();
        }

        return 0;

unlock:
        rcu_read_unlock();
        return 0;
}

/* free old vis packets. Must be called with this vis_hash_lock
 * held
 */
static void batadv_purge_vis_packets(struct batadv_priv *bat_priv)
{
        uint32_t i;
        struct batadv_hashtable *hash = bat_priv->vis.hash;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        struct batadv_vis_info *info;

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

                hlist_for_each_entry_safe(info, node_tmp,
                                          head, hash_entry) {
                        /* never purge own data. */
                        if (info == bat_priv->vis.my_info)
                                continue;

                        if (batadv_has_timed_out(info->first_seen,
                                                 BATADV_VIS_TIMEOUT)) {
                                hlist_del(&info->hash_entry);
                                batadv_send_list_del(info);
                                kref_put(&info->refcount, batadv_free_info);
                        }
                }
        }
}

static void batadv_broadcast_vis_packet(struct batadv_priv *bat_priv,
                                        struct batadv_vis_info *info)
{
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct hlist_head *head;
        struct batadv_orig_node *orig_node;
        struct batadv_vis_packet *packet;
        struct sk_buff *skb;
        uint32_t i;


        packet = (struct batadv_vis_packet *)info->skb_packet->data;

        /* send to all routers in range. */
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        /* if it's a vis server and reachable, send it. */
                        if (!(orig_node->flags & BATADV_VIS_SERVER))
                                continue;

                        /* don't send it if we already received the packet from
                         * this node.
                         */
                        if (batadv_recv_list_is_in(bat_priv, &info->recv_list,
                                                   orig_node->orig))
                                continue;

                        memcpy(packet->target_orig, orig_node->orig, ETH_ALEN);
                        skb = skb_clone(info->skb_packet, GFP_ATOMIC);
                        if (!skb)
                                continue;

                        if (!batadv_send_skb_to_orig(skb, orig_node, NULL))
                                kfree_skb(skb);
                }
                rcu_read_unlock();
        }
}

static void batadv_unicast_vis_packet(struct batadv_priv *bat_priv,
                                      struct batadv_vis_info *info)
{
        struct batadv_orig_node *orig_node;
        struct sk_buff *skb;
        struct batadv_vis_packet *packet;

        packet = (struct batadv_vis_packet *)info->skb_packet->data;

        orig_node = batadv_orig_hash_find(bat_priv, packet->target_orig);
        if (!orig_node)
                goto out;

        skb = skb_clone(info->skb_packet, GFP_ATOMIC);
        if (!skb)
                goto out;

        if (!batadv_send_skb_to_orig(skb, orig_node, NULL))
                kfree_skb(skb);

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

/* only send one vis packet. called from batadv_send_vis_packets() */
static void batadv_send_vis_packet(struct batadv_priv *bat_priv,
                                   struct batadv_vis_info *info)
{
        struct batadv_hard_iface *primary_if;
        struct batadv_vis_packet *packet;

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

        packet = (struct batadv_vis_packet *)info->skb_packet->data;
        if (packet->header.ttl < 2) {
                pr_debug("Error - can't send vis packet: ttl exceeded\n");
                goto out;
        }

        memcpy(packet->sender_orig, primary_if->net_dev->dev_addr, ETH_ALEN);
        packet->header.ttl--;

        if (is_broadcast_ether_addr(packet->target_orig))
                batadv_broadcast_vis_packet(bat_priv, info);
        else
                batadv_unicast_vis_packet(bat_priv, info);
        packet->header.ttl++; /* restore TTL */

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

/* called from timer; send (and maybe generate) vis packet. */
static void batadv_send_vis_packets(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_priv *bat_priv;
        struct batadv_priv_vis *priv_vis;
        struct batadv_vis_info *info;

        delayed_work = container_of(work, struct delayed_work, work);
        priv_vis = container_of(delayed_work, struct batadv_priv_vis, work);
        bat_priv = container_of(priv_vis, struct batadv_priv, vis);
        spin_lock_bh(&bat_priv->vis.hash_lock);
        batadv_purge_vis_packets(bat_priv);

        if (batadv_generate_vis_packet(bat_priv) == 0) {
                /* schedule if generation was successful */
                batadv_send_list_add(bat_priv, bat_priv->vis.my_info);
        }

        while (!list_empty(&bat_priv->vis.send_list)) {
                info = list_first_entry(&bat_priv->vis.send_list,
                                        typeof(*info), send_list);

                kref_get(&info->refcount);
                spin_unlock_bh(&bat_priv->vis.hash_lock);

                batadv_send_vis_packet(bat_priv, info);

                spin_lock_bh(&bat_priv->vis.hash_lock);
                batadv_send_list_del(info);
                kref_put(&info->refcount, batadv_free_info);
        }
        spin_unlock_bh(&bat_priv->vis.hash_lock);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->vis.work,
                           msecs_to_jiffies(BATADV_VIS_INTERVAL));
}

/* init the vis server. this may only be called when if_list is already
 * initialized (e.g. bat0 is initialized, interfaces have been added)
 */
int batadv_vis_init(struct batadv_priv *bat_priv)
{
        struct batadv_vis_packet *packet;
        int hash_added;
        unsigned int len;
        unsigned long first_seen;
        struct sk_buff *tmp_skb;

        if (bat_priv->vis.hash)
                return 0;

        spin_lock_bh(&bat_priv->vis.hash_lock);

        bat_priv->vis.hash = batadv_hash_new(256);
        if (!bat_priv->vis.hash) {
                pr_err("Can't initialize vis_hash\n");
                goto err;
        }

        batadv_hash_set_lock_class(bat_priv->vis.hash,
                                   &batadv_vis_hash_lock_class_key);

        bat_priv->vis.my_info = kmalloc(BATADV_MAX_VIS_PACKET_SIZE, GFP_ATOMIC);
        if (!bat_priv->vis.my_info)
                goto err;

        len = sizeof(*packet) + BATADV_MAX_VIS_PACKET_SIZE;
        len += ETH_HLEN + NET_IP_ALIGN;
        bat_priv->vis.my_info->skb_packet = dev_alloc_skb(len);
        if (!bat_priv->vis.my_info->skb_packet)
                goto free_info;

        skb_reserve(bat_priv->vis.my_info->skb_packet, ETH_HLEN + NET_IP_ALIGN);
        tmp_skb = bat_priv->vis.my_info->skb_packet;
        packet = (struct batadv_vis_packet *)skb_put(tmp_skb, sizeof(*packet));

        /* prefill the vis info */
        first_seen = jiffies - msecs_to_jiffies(BATADV_VIS_INTERVAL);
        bat_priv->vis.my_info->first_seen = first_seen;
        INIT_LIST_HEAD(&bat_priv->vis.my_info->recv_list);
        INIT_LIST_HEAD(&bat_priv->vis.my_info->send_list);
        kref_init(&bat_priv->vis.my_info->refcount);
        bat_priv->vis.my_info->bat_priv = bat_priv;
        packet->header.version = BATADV_COMPAT_VERSION;
        packet->header.packet_type = BATADV_VIS;
        packet->header.ttl = BATADV_TTL;
        packet->seqno = 0;
        packet->reserved = 0;
        packet->entries = 0;

        INIT_LIST_HEAD(&bat_priv->vis.send_list);

        hash_added = batadv_hash_add(bat_priv->vis.hash, batadv_vis_info_cmp,
                                     batadv_vis_info_choose,
                                     bat_priv->vis.my_info,
                                     &bat_priv->vis.my_info->hash_entry);
        if (hash_added != 0) {
                pr_err("Can't add own vis packet into hash\n");
                /* not in hash, need to remove it manually. */
                kref_put(&bat_priv->vis.my_info->refcount, batadv_free_info);
                goto err;
        }

        spin_unlock_bh(&bat_priv->vis.hash_lock);

        INIT_DELAYED_WORK(&bat_priv->vis.work, batadv_send_vis_packets);
        queue_delayed_work(batadv_event_workqueue, &bat_priv->vis.work,
                           msecs_to_jiffies(BATADV_VIS_INTERVAL));

        return 0;

free_info:
        kfree(bat_priv->vis.my_info);
        bat_priv->vis.my_info = NULL;
err:
        spin_unlock_bh(&bat_priv->vis.hash_lock);
        batadv_vis_quit(bat_priv);
        return -ENOMEM;
}

/* Decrease the reference count on a hash item info */
static void batadv_free_info_ref(struct hlist_node *node, void *arg)
{
        struct batadv_vis_info *info;

        info = container_of(node, struct batadv_vis_info, hash_entry);
        batadv_send_list_del(info);
        kref_put(&info->refcount, batadv_free_info);
}

/* shutdown vis-server */
void batadv_vis_quit(struct batadv_priv *bat_priv)
{
        if (!bat_priv->vis.hash)
                return;

        cancel_delayed_work_sync(&bat_priv->vis.work);

        spin_lock_bh(&bat_priv->vis.hash_lock);
        /* properly remove, kill timers ... */
        batadv_hash_delete(bat_priv->vis.hash, batadv_free_info_ref, NULL);
        bat_priv->vis.hash = NULL;
        bat_priv->vis.my_info = NULL;
        spin_unlock_bh(&bat_priv->vis.hash_lock);
}