vis.c

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/* Copyright (C) 2008-2012 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

static void batadv_start_vis_timer(struct batadv_priv *bat_priv);

/* free the info */
static void batadv_free_info(struct kref *ref)
{
    struct batadv_vis_info *info;
    struct batadv_priv *bat_priv;
    struct batadv_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 hlist_node *node;
    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, node, head, hash_entry) {
        if (!batadv_vis_info_cmp(node, 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_if_list_entry *entry;
    struct hlist_node *pos;

    hlist_for_each_entry(entry, pos, 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_if_list_entry *entry;
    struct hlist_node *pos;

    hlist_for_each_entry(entry, pos, if_list, list) {
        if (entry->primary)
            seq_printf(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_if_list_entry *entry;
    struct hlist_node *pos;

    hlist_for_each_entry(entry, pos, 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_printf(seq, "\n");
    }
}

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

    HLIST_HEAD(vis_if_list);

    hlist_for_each_entry_rcu(info, node, 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, pos, 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_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_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);
    if (!info->skb_packet) {
        kfree(info);
        return NULL;
    }
    skb_reserve(info->skb_packet, ETH_HLEN);
    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(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(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_node *node;
    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, 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_node *node;
    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, 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, node, 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, *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, 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(node);
                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_neigh_node *router;
    struct batadv_hashtable *hash = bat_priv->orig_hash;
    struct hlist_node *node;
    struct hlist_head *head;
    struct batadv_orig_node *orig_node;
    struct batadv_vis_packet *packet;
    struct sk_buff *skb;
    struct batadv_hard_iface *hard_iface;
    uint8_t dstaddr[ETH_ALEN];
    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, node, head, hash_entry) {
            /* if it's a vis server and reachable, send it. */
            if (!(orig_node->flags & BATADV_VIS_SERVER))
                continue;

            router = batadv_orig_node_get_router(orig_node);
            if (!router)
                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)) {
                batadv_neigh_node_free_ref(router);
                continue;
            }

            memcpy(packet->target_orig, orig_node->orig, ETH_ALEN);
            hard_iface = router->if_incoming;
            memcpy(dstaddr, router->addr, ETH_ALEN);

            batadv_neigh_node_free_ref(router);

            skb = skb_clone(info->skb_packet, GFP_ATOMIC);
            if (skb)
                batadv_send_skb_packet(skb, hard_iface,
                               dstaddr);

        }
        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 batadv_neigh_node *router = NULL;
    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;

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

    skb = skb_clone(info->skb_packet, GFP_ATOMIC);
    if (skb)
        batadv_send_skb_packet(skb, router->if_incoming, router->addr);

out:
    if (router)
        batadv_neigh_node_free_ref(router);
    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);
    batadv_start_vis_timer(bat_priv);
}

/* 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;
    }

    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 + ETH_HLEN;
    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);
    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);
    batadv_start_vis_timer(bat_priv);
    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);
}

/* schedule packets for (re)transmission */
static void batadv_start_vis_timer(struct batadv_priv *bat_priv)
{
    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));
}