/* Copyright (C) 2007-2014 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, see <http://www.gnu.org/licenses/>.
 */

#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 "gateway_common.h"
#include "gateway_client.h"
#include "originator.h"
#include "network-coding.h"
#include "fragmentation.h"
#include "multicast.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 batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        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 = eth_hdr(skb);
        ether_addr_copy(ethhdr->h_source, hard_iface->net_dev->dev_addr);
        ether_addr_copy(ethhdr->h_dest, dst_addr);
        ethhdr->h_proto = htons(ETH_P_BATMAN);

        skb_set_network_header(skb, ETH_HLEN);
        skb->protocol = htons(ETH_P_BATMAN);

        skb->dev = hard_iface->net_dev;

        /* Save a clone of the skb to use when decoding coded packets */
        batadv_nc_skb_store_for_decoding(bat_priv, skb);

        /* 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 NET_XMIT_SUCCESS on success, NET_XMIT_DROP on failure, or
 * NET_XMIT_POLICED if the skb is buffered for later transmit.
 */
int 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;
        int ret = NET_XMIT_DROP;

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

        /* Check if the skb is too large to send in one piece and fragment
         * it if needed.
         */
        if (atomic_read(&bat_priv->fragmentation) &&
            skb->len > neigh_node->if_incoming->net_dev->mtu) {
                /* Fragment and send packet. */
                if (batadv_frag_send_packet(skb, orig_node, neigh_node))
                        ret = NET_XMIT_SUCCESS;

                goto out;
        }

        /* try to network code the packet, if it is received on an interface
         * (i.e. being forwarded). If the packet originates from this node or if
         * network coding fails, then send the packet as usual.
         */
        if (recv_if && batadv_nc_skb_forward(skb, neigh_node)) {
                ret = NET_XMIT_POLICED;
        } else {
                batadv_send_skb_packet(skb, neigh_node->if_incoming,
                                       neigh_node->addr);
                ret = NET_XMIT_SUCCESS;
        }

out:
        if (neigh_node)
                batadv_neigh_node_free_ref(neigh_node);

        return ret;
}

/**
 * batadv_send_skb_push_fill_unicast - extend the buffer and initialize the
 *  common fields for unicast packets
 * @skb: the skb carrying the unicast header to initialize
 * @hdr_size: amount of bytes to push at the beginning of the skb
 * @orig_node: the destination node
 *
 * Returns false if the buffer extension was not possible or true otherwise.
 */
static bool
batadv_send_skb_push_fill_unicast(struct sk_buff *skb, int hdr_size,
                                  struct batadv_orig_node *orig_node)
{
        struct batadv_unicast_packet *unicast_packet;
        uint8_t ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);

        if (batadv_skb_head_push(skb, hdr_size) < 0)
                return false;

        unicast_packet = (struct batadv_unicast_packet *)skb->data;
        unicast_packet->version = BATADV_COMPAT_VERSION;
        /* batman packet type: unicast */
        unicast_packet->packet_type = BATADV_UNICAST;
        /* set unicast ttl */
        unicast_packet->ttl = BATADV_TTL;
        /* copy the destination for faster routing */
        ether_addr_copy(unicast_packet->dest, orig_node->orig);
        /* set the destination tt version number */
        unicast_packet->ttvn = ttvn;

        return true;
}

/**
 * batadv_send_skb_prepare_unicast - encapsulate an skb with a unicast header
 * @skb: the skb containing the payload to encapsulate
 * @orig_node: the destination node
 *
 * Returns false if the payload could not be encapsulated or true otherwise.
 */
static bool batadv_send_skb_prepare_unicast(struct sk_buff *skb,
                                            struct batadv_orig_node *orig_node)
{
        size_t uni_size = sizeof(struct batadv_unicast_packet);

        return batadv_send_skb_push_fill_unicast(skb, uni_size, orig_node);
}

/**
 * batadv_send_skb_prepare_unicast_4addr - encapsulate an skb with a
 *  unicast 4addr header
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the skb containing the payload to encapsulate
 * @orig_node: the destination node
 * @packet_subtype: the unicast 4addr packet subtype to use
 *
 * Returns false if the payload could not be encapsulated or true otherwise.
 */
bool batadv_send_skb_prepare_unicast_4addr(struct batadv_priv *bat_priv,
                                           struct sk_buff *skb,
                                           struct batadv_orig_node *orig,
                                           int packet_subtype)
{
        struct batadv_hard_iface *primary_if;
        struct batadv_unicast_4addr_packet *uc_4addr_packet;
        bool ret = false;

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

        /* Pull the header space and fill the unicast_packet substructure.
         * We can do that because the first member of the uc_4addr_packet
         * is of type struct unicast_packet
         */
        if (!batadv_send_skb_push_fill_unicast(skb, sizeof(*uc_4addr_packet),
                                               orig))
                goto out;

        uc_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
        uc_4addr_packet->u.packet_type = BATADV_UNICAST_4ADDR;
        ether_addr_copy(uc_4addr_packet->src, primary_if->net_dev->dev_addr);
        uc_4addr_packet->subtype = packet_subtype;
        uc_4addr_packet->reserved = 0;

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

/**
 * batadv_send_skb_unicast - encapsulate and send an skb via unicast
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: payload to send
 * @packet_type: the batman unicast packet type to use
 * @packet_subtype: the unicast 4addr packet subtype (only relevant for unicast
 *  4addr packets)
 * @orig_node: the originator to send the packet to
 * @vid: the vid to be used to search the translation table
 *
 * Wrap the given skb into a batman-adv unicast or unicast-4addr header
 * depending on whether BATADV_UNICAST or BATADV_UNICAST_4ADDR was supplied
 * as packet_type. Then send this frame to the given orig_node and release a
 * reference to this orig_node.
 *
 * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
 */
int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
                            struct sk_buff *skb, int packet_type,
                            int packet_subtype,
                            struct batadv_orig_node *orig_node,
                            unsigned short vid)
{
        struct ethhdr *ethhdr;
        struct batadv_unicast_packet *unicast_packet;
        int ret = NET_XMIT_DROP;

        if (!orig_node)
                goto out;

        switch (packet_type) {
        case BATADV_UNICAST:
                if (!batadv_send_skb_prepare_unicast(skb, orig_node))
                        goto out;
                break;
        case BATADV_UNICAST_4ADDR:
                if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, skb,
                                                           orig_node,
                                                           packet_subtype))
                        goto out;
                break;
        default:
                /* this function supports UNICAST and UNICAST_4ADDR only. It
                 * should never be invoked with any other packet type
                 */
                goto out;
        }

        /* skb->data might have been reallocated by
         * batadv_send_skb_prepare_unicast{,_4addr}()
         */
        ethhdr = eth_hdr(skb);
        unicast_packet = (struct batadv_unicast_packet *)skb->data;

        /* inform the destination node that we are still missing a correct route
         * for this client. The destination will receive this packet and will
         * try to reroute it because the ttvn contained in the header is less
         * than the current one
         */
        if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest, vid))
                unicast_packet->ttvn = unicast_packet->ttvn - 1;

        if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP)
                ret = NET_XMIT_SUCCESS;

out:
        if (orig_node)
                batadv_orig_node_free_ref(orig_node);
        if (ret == NET_XMIT_DROP)
                kfree_skb(skb);
        return ret;
}

/**
 * batadv_send_skb_via_tt_generic - send an skb via TT lookup
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: payload to send
 * @packet_type: the batman unicast packet type to use
 * @packet_subtype: the unicast 4addr packet subtype (only relevant for unicast
 *  4addr packets)
 * @dst_hint: can be used to override the destination contained in the skb
 * @vid: the vid to be used to search the translation table
 *
 * Look up the recipient node for the destination address in the ethernet
 * header via the translation table. Wrap the given skb into a batman-adv
 * unicast or unicast-4addr header depending on whether BATADV_UNICAST or
 * BATADV_UNICAST_4ADDR was supplied as packet_type. Then send this frame
 * to the according destination node.
 *
 * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
 */
int batadv_send_skb_via_tt_generic(struct batadv_priv *bat_priv,
                                   struct sk_buff *skb, int packet_type,
                                   int packet_subtype, uint8_t *dst_hint,
                                   unsigned short vid)
{
        struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
        struct batadv_orig_node *orig_node;
        uint8_t *src, *dst;

        src = ethhdr->h_source;
        dst = ethhdr->h_dest;

        /* if we got an hint! let's send the packet to this client (if any) */
        if (dst_hint) {
                src = NULL;
                dst = dst_hint;
        }
        orig_node = batadv_transtable_search(bat_priv, src, dst, vid);

        return batadv_send_skb_unicast(bat_priv, skb, packet_type,
                                       packet_subtype, orig_node, vid);
}

/**
 * batadv_send_skb_via_gw - send an skb via gateway lookup
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: payload to send
 * @vid: the vid to be used to search the translation table
 *
 * Look up the currently selected gateway. Wrap the given skb into a batman-adv
 * unicast header and send this frame to this gateway node.
 *
 * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
 */
int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
                           unsigned short vid)
{
        struct batadv_orig_node *orig_node;

        orig_node = batadv_gw_get_selected_orig(bat_priv);
        return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
                                       orig_node, vid);
}

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);
        if (forw_packet->if_outgoing)
                batadv_hardif_free_ref(forw_packet->if_outgoing);
        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)
{
        /* 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->ttl--;

        skb_reset_mac_header(newskb);

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

        /* 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;

                if (forw_packet->num_packets >= hard_iface->num_bcasts)
                        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 < BATADV_NUM_BCASTS_MAX) {
                _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.
         *
         * only re-schedule if this is the "original" copy, e.g. the OGM of the
         * primary interface should only be rescheduled once per period, but
         * this function will be called for the forw_packet instances of the
         * other secondary interfaces as well.
         */
        if (forw_packet->own &&
            forw_packet->if_incoming == forw_packet->if_outgoing)
                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) &&
                    (forw_packet->if_outgoing != 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);
}