/* Copyright (C) 2007-2013 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, 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 "distributed-arp-table.h"
#include "send.h"
#include "routing.h"
#include "translation-table.h"
#include "soft-interface.h"
#include "hard-interface.h"
#include "vis.h"
#include "gateway_common.h"
#include "originator.h"

#include <linux/if_ether.h>

static void batadv_send_outstanding_bcast_packet(struct work_struct *work);

/* send out an already prepared packet to the given address via the
 * specified batman interface
 */
int batadv_send_skb_packet(struct sk_buff *skb,
                           struct batadv_hard_iface *hard_iface,
                           const uint8_t *dst_addr)
{
        struct ethhdr *ethhdr;

        if (hard_iface->if_status != BATADV_IF_ACTIVE)
                goto send_skb_err;

        if (unlikely(!hard_iface->net_dev))
                goto send_skb_err;

        if (!(hard_iface->net_dev->flags & IFF_UP)) {
                pr_warn("Interface %s is not up - can't send packet via that interface!\n",
                        hard_iface->net_dev->name);
                goto send_skb_err;
        }

        /* push to the ethernet header. */
        if (batadv_skb_head_push(skb, ETH_HLEN) < 0)
                goto send_skb_err;

        skb_reset_mac_header(skb);

        ethhdr = (struct ethhdr *)skb_mac_header(skb);
        memcpy(ethhdr->h_source, hard_iface->net_dev->dev_addr, ETH_ALEN);
        memcpy(ethhdr->h_dest, dst_addr, ETH_ALEN);
        ethhdr->h_proto = __constant_htons(ETH_P_BATMAN);

        skb_set_network_header(skb, ETH_HLEN);
        skb->priority = TC_PRIO_CONTROL;
        skb->protocol = __constant_htons(ETH_P_BATMAN);

        skb->dev = hard_iface->net_dev;

        /* dev_queue_xmit() returns a negative result on error.  However on
         * congestion and traffic shaping, it drops and returns NET_XMIT_DROP
         * (which is > 0). This will not be treated as an error.
         */
        return dev_queue_xmit(skb);
send_skb_err:
        kfree_skb(skb);
        return NET_XMIT_DROP;
}

/**
 * batadv_send_skb_to_orig - Lookup next-hop and transmit skb.
 * @skb: Packet to be transmitted.
 * @orig_node: Final destination of the packet.
 * @recv_if: Interface used when receiving the packet (can be NULL).
 *
 * Looks up the best next-hop towards the passed originator and passes the
 * skb on for preparation of MAC header. If the packet originated from this
 * host, NULL can be passed as recv_if and no interface alternating is
 * attempted.
 *
 * Returns TRUE on success; FALSE otherwise.
 */
bool batadv_send_skb_to_orig(struct sk_buff *skb,
                             struct batadv_orig_node *orig_node,
                             struct batadv_hard_iface *recv_if)
{
        struct batadv_priv *bat_priv = orig_node->bat_priv;
        struct batadv_neigh_node *neigh_node;

        /* batadv_find_router() increases neigh_nodes refcount if found. */
        neigh_node = batadv_find_router(bat_priv, orig_node, recv_if);
        if (!neigh_node)
                return false;

        /* route it */
        batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);

        batadv_neigh_node_free_ref(neigh_node);

        return true;
}

void batadv_schedule_bat_ogm(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);

        if ((hard_iface->if_status == BATADV_IF_NOT_IN_USE) ||
            (hard_iface->if_status == BATADV_IF_TO_BE_REMOVED))
                return;

        /* the interface gets activated here to avoid race conditions between
         * the moment of activating the interface in
         * hardif_activate_interface() where the originator mac is set and
         * outdated packets (especially uninitialized mac addresses) in the
         * packet queue
         */
        if (hard_iface->if_status == BATADV_IF_TO_BE_ACTIVATED)
                hard_iface->if_status = BATADV_IF_ACTIVE;

        bat_priv->bat_algo_ops->bat_ogm_schedule(hard_iface);
}

static void batadv_forw_packet_free(struct batadv_forw_packet *forw_packet)
{
        if (forw_packet->skb)
                kfree_skb(forw_packet->skb);
        if (forw_packet->if_incoming)
                batadv_hardif_free_ref(forw_packet->if_incoming);
        kfree(forw_packet);
}

static void
_batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
                                 struct batadv_forw_packet *forw_packet,
                                 unsigned long send_time)
{
        INIT_HLIST_NODE(&forw_packet->list);

        /* add new packet to packet list */
        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_add_head(&forw_packet->list, &bat_priv->forw_bcast_list);
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        /* start timer for this packet */
        queue_delayed_work(batadv_event_workqueue, &forw_packet->delayed_work,
                           send_time);
}

/* add a broadcast packet to the queue and setup timers. broadcast packets
 * are sent multiple times to increase probability for being received.
 *
 * This function returns NETDEV_TX_OK on success and NETDEV_TX_BUSY on
 * errors.
 *
 * The skb is not consumed, so the caller should make sure that the
 * skb is freed.
 */
int batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
                                    const struct sk_buff *skb,
                                    unsigned long delay)
{
        struct batadv_hard_iface *primary_if = NULL;
        struct batadv_forw_packet *forw_packet;
        struct batadv_bcast_packet *bcast_packet;
        struct sk_buff *newskb;

        if (!batadv_atomic_dec_not_zero(&bat_priv->bcast_queue_left)) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "bcast packet queue full\n");
                goto out;
        }

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

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

        if (!forw_packet)
                goto out_and_inc;

        newskb = skb_copy(skb, GFP_ATOMIC);
        if (!newskb)
                goto packet_free;

        /* as we have a copy now, it is safe to decrease the TTL */
        bcast_packet = (struct batadv_bcast_packet *)newskb->data;
        bcast_packet->header.ttl--;

        skb_reset_mac_header(newskb);

        forw_packet->skb = newskb;
        forw_packet->if_incoming = primary_if;

        /* how often did we send the bcast packet ? */
        forw_packet->num_packets = 0;

        INIT_DELAYED_WORK(&forw_packet->delayed_work,
                          batadv_send_outstanding_bcast_packet);

        _batadv_add_bcast_packet_to_list(bat_priv, forw_packet, delay);
        return NETDEV_TX_OK;

packet_free:
        kfree(forw_packet);
out_and_inc:
        atomic_inc(&bat_priv->bcast_queue_left);
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return NETDEV_TX_BUSY;
}

static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
{
        struct batadv_hard_iface *hard_iface;
        struct delayed_work *delayed_work;
        struct batadv_forw_packet *forw_packet;
        struct sk_buff *skb1;
        struct net_device *soft_iface;
        struct batadv_priv *bat_priv;

        delayed_work = container_of(work, struct delayed_work, work);
        forw_packet = container_of(delayed_work, struct batadv_forw_packet,
                                   delayed_work);
        soft_iface = forw_packet->if_incoming->soft_iface;
        bat_priv = netdev_priv(soft_iface);

        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_del(&forw_packet->list);
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
                goto out;

        if (batadv_dat_drop_broadcast_packet(bat_priv, forw_packet))
                goto out;

        /* rebroadcast packet */
        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->soft_iface != soft_iface)
                        continue;

                /* send a copy of the saved skb */
                skb1 = skb_clone(forw_packet->skb, GFP_ATOMIC);
                if (skb1)
                        batadv_send_skb_packet(skb1, hard_iface,
                                               batadv_broadcast_addr);
        }
        rcu_read_unlock();

        forw_packet->num_packets++;

        /* if we still have some more bcasts to send */
        if (forw_packet->num_packets < 3) {
                _batadv_add_bcast_packet_to_list(bat_priv, forw_packet,
                                                 msecs_to_jiffies(5));
                return;
        }

out:
        batadv_forw_packet_free(forw_packet);
        atomic_inc(&bat_priv->bcast_queue_left);
}

void batadv_send_outstanding_bat_ogm_packet(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_forw_packet *forw_packet;
        struct batadv_priv *bat_priv;

        delayed_work = container_of(work, struct delayed_work, work);
        forw_packet = container_of(delayed_work, struct batadv_forw_packet,
                                   delayed_work);
        bat_priv = netdev_priv(forw_packet->if_incoming->soft_iface);
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_del(&forw_packet->list);
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);

        if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
                goto out;

        bat_priv->bat_algo_ops->bat_ogm_emit(forw_packet);

        /* we have to have at least one packet in the queue
         * to determine the queues wake up time unless we are
         * shutting down
         */
        if (forw_packet->own)
                batadv_schedule_bat_ogm(forw_packet->if_incoming);

out:
        /* don't count own packet */
        if (!forw_packet->own)
                atomic_inc(&bat_priv->batman_queue_left);

        batadv_forw_packet_free(forw_packet);
}

void
batadv_purge_outstanding_packets(struct batadv_priv *bat_priv,
                                 const struct batadv_hard_iface *hard_iface)
{
        struct batadv_forw_packet *forw_packet;
        struct hlist_node *safe_tmp_node;
        bool pending;

        if (hard_iface)
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "purge_outstanding_packets(): %s\n",
                           hard_iface->net_dev->name);
        else
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "purge_outstanding_packets()\n");

        /* free bcast list */
        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_for_each_entry_safe(forw_packet, safe_tmp_node,
                                  &bat_priv->forw_bcast_list, list) {
                /* if purge_outstanding_packets() was called with an argument
                 * we delete only packets belonging to the given interface
                 */
                if ((hard_iface) &&
                    (forw_packet->if_incoming != hard_iface))
                        continue;

                spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

                /* batadv_send_outstanding_bcast_packet() will lock the list to
                 * delete the item from the list
                 */
                pending = cancel_delayed_work_sync(&forw_packet->delayed_work);
                spin_lock_bh(&bat_priv->forw_bcast_list_lock);

                if (pending) {
                        hlist_del(&forw_packet->list);
                        batadv_forw_packet_free(forw_packet);
                }
        }
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        /* free batman packet list */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_for_each_entry_safe(forw_packet, safe_tmp_node,
                                  &bat_priv->forw_bat_list, list) {
                /* if purge_outstanding_packets() was called with an argument
                 * we delete only packets belonging to the given interface
                 */
                if ((hard_iface) &&
                    (forw_packet->if_incoming != hard_iface))
                        continue;

                spin_unlock_bh(&bat_priv->forw_bat_list_lock);

                /* send_outstanding_bat_packet() will lock the list to
                 * delete the item from the list
                 */
                pending = cancel_delayed_work_sync(&forw_packet->delayed_work);
                spin_lock_bh(&bat_priv->forw_bat_list_lock);

                if (pending) {
                        hlist_del(&forw_packet->list);
                        batadv_forw_packet_free(forw_packet);
                }
        }
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);
}