/*

   * Copyright (C) 2007-2011 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 "routing.h"
  #include "send.h"

  #include "soft-interface.h"
  #include "hard-interface.h"
  #include "icmp_socket.h"
  #include "translation-table.h"
  #include "originator.h"

  #include "vis.h"

  #include "unicast.h"

  #include "bat_ogm.h"

  void slide_own_bcast_window(struct hard_iface *hard_iface)

  {

  	struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);

  	struct hashtable_t *hash = bat_priv->orig_hash;

  	struct hlist_node *node;

  	struct hlist_head *head;

  	struct orig_node *orig_node;
  	unsigned long *word;

  	uint32_t i;

  	size_t word_index;

  	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) {

  			spin_lock_bh(&orig_node->ogm_cnt_lock);

  			word_index = hard_iface->if_num * NUM_WORDS;

  			word = &(orig_node->bcast_own[word_index]);
  
  			bit_get_packet(bat_priv, word, 1, 0);

  			orig_node->bcast_own_sum[hard_iface->if_num] =

  				bit_packet_count(word);

  			spin_unlock_bh(&orig_node->ogm_cnt_lock);

  		}

  		rcu_read_unlock();

  	}

  }

  static void _update_route(struct bat_priv *bat_priv,
  			  struct orig_node *orig_node,
  			  struct neigh_node *neigh_node)

  {

  	struct neigh_node *curr_router;
  
  	curr_router = orig_node_get_router(orig_node);

  	/* route deleted */

  	if ((curr_router) && (!neigh_node)) {

  		bat_dbg(DBG_ROUTES, bat_priv, "Deleting route towards: %pM
  ",
  			orig_node->orig);

  		tt_global_del_orig(bat_priv, orig_node,

  				    "Deleted route towards originator");

  	/* route added */
  	} else if ((!curr_router) && (neigh_node)) {

  
  		bat_dbg(DBG_ROUTES, bat_priv,
  			"Adding route towards: %pM (via %pM)
  ",
  			orig_node->orig, neigh_node->addr);

  	/* route changed */

  	} else if (neigh_node && curr_router) {

  		bat_dbg(DBG_ROUTES, bat_priv,
  			"Changing route towards: %pM "
  			"(now via %pM - was via %pM)
  ",
  			orig_node->orig, neigh_node->addr,

  			curr_router->addr);

  	}

  	if (curr_router)
  		neigh_node_free_ref(curr_router);
  
  	/* increase refcount of new best neighbor */

  	if (neigh_node && !atomic_inc_not_zero(&neigh_node->refcount))
  		neigh_node = NULL;

  
  	spin_lock_bh(&orig_node->neigh_list_lock);
  	rcu_assign_pointer(orig_node->router, neigh_node);
  	spin_unlock_bh(&orig_node->neigh_list_lock);
  
  	/* decrease refcount of previous best neighbor */
  	if (curr_router)
  		neigh_node_free_ref(curr_router);

  }

  void update_route(struct bat_priv *bat_priv, struct orig_node *orig_node,
  		  struct neigh_node *neigh_node)

  {

  	struct neigh_node *router = NULL;

  
  	if (!orig_node)

  		goto out;
  
  	router = orig_node_get_router(orig_node);

  	if (router != neigh_node)

  		_update_route(bat_priv, orig_node, neigh_node);

  
  out:
  	if (router)
  		neigh_node_free_ref(router);

  }

  /* caller must hold the neigh_list_lock */
  void bonding_candidate_del(struct orig_node *orig_node,
  			   struct neigh_node *neigh_node)
  {
  	/* this neighbor is not part of our candidate list */
  	if (list_empty(&neigh_node->bonding_list))
  		goto out;
  
  	list_del_rcu(&neigh_node->bonding_list);

  	INIT_LIST_HEAD(&neigh_node->bonding_list);

  	neigh_node_free_ref(neigh_node);

  	atomic_dec(&orig_node->bond_candidates);
  
  out:
  	return;
  }

  void bonding_candidate_add(struct orig_node *orig_node,
  			   struct neigh_node *neigh_node)

  {
  	struct hlist_node *node;

  	struct neigh_node *tmp_neigh_node, *router = NULL;
  	uint8_t interference_candidate = 0;

  
  	spin_lock_bh(&orig_node->neigh_list_lock);
  
  	/* only consider if it has the same primary address ...  */

  	if (!compare_eth(orig_node->orig,
  			 neigh_node->orig_node->primary_addr))

  		goto candidate_del;

  	router = orig_node_get_router(orig_node);
  	if (!router)

  		goto candidate_del;

  	/* ... and is good enough to be considered */

  	if (neigh_node->tq_avg < router->tq_avg - BONDING_TQ_THRESHOLD)

  		goto candidate_del;
  
  	/**
  	 * check if we have another candidate with the same mac address or
  	 * interface. If we do, we won't select this candidate because of
  	 * possible interference.
  	 */
  	hlist_for_each_entry_rcu(tmp_neigh_node, node,
  				 &orig_node->neigh_list, list) {
  
  		if (tmp_neigh_node == neigh_node)
  			continue;
  
  		/* we only care if the other candidate is even
  		* considered as candidate. */
  		if (list_empty(&tmp_neigh_node->bonding_list))
  			continue;
  
  		if ((neigh_node->if_incoming == tmp_neigh_node->if_incoming) ||

  		    (compare_eth(neigh_node->addr, tmp_neigh_node->addr))) {

  			interference_candidate = 1;
  			break;
  		}
  	}
  
  	/* don't care further if it is an interference candidate */
  	if (interference_candidate)
  		goto candidate_del;
  
  	/* this neighbor already is part of our candidate list */
  	if (!list_empty(&neigh_node->bonding_list))
  		goto out;

  	if (!atomic_inc_not_zero(&neigh_node->refcount))
  		goto out;

  	list_add_rcu(&neigh_node->bonding_list, &orig_node->bond_list);

  	atomic_inc(&orig_node->bond_candidates);
  	goto out;
  
  candidate_del:
  	bonding_candidate_del(orig_node, neigh_node);
  
  out:
  	spin_unlock_bh(&orig_node->neigh_list_lock);

  
  	if (router)
  		neigh_node_free_ref(router);

  }
  
  /* copy primary address for bonding */

  void bonding_save_primary(const struct orig_node *orig_node,
  			  struct orig_node *orig_neigh_node,
  			  const struct batman_ogm_packet *batman_ogm_packet)

  {

  	if (!(batman_ogm_packet->flags & PRIMARIES_FIRST_HOP))

  		return;
  
  	memcpy(orig_neigh_node->primary_addr, orig_node->orig, ETH_ALEN);
  }

  /* checks whether the host restarted and is in the protection time.
   * returns:
   *  0 if the packet is to be accepted
   *  1 if the packet is to be ignored.
   */

  int window_protected(struct bat_priv *bat_priv, int32_t seq_num_diff,
  		     unsigned long *last_reset)

  {
  	if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE)
  		|| (seq_num_diff >= EXPECTED_SEQNO_RANGE)) {
  		if (time_after(jiffies, *last_reset +
  			msecs_to_jiffies(RESET_PROTECTION_MS))) {
  
  			*last_reset = jiffies;
  			bat_dbg(DBG_BATMAN, bat_priv,
  				"old packet received, start protection
  ");
  
  			return 0;
  		} else
  			return 1;
  	}
  	return 0;
  }

  int recv_bat_ogm_packet(struct sk_buff *skb, struct hard_iface *hard_iface)

  {

  	struct ethhdr *ethhdr;
  
  	/* drop packet if it has not necessary minimum size */

  	if (unlikely(!pskb_may_pull(skb, BATMAN_OGM_LEN)))

  		return NET_RX_DROP;
  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with broadcast indication but unicast recipient */
  	if (!is_broadcast_ether_addr(ethhdr->h_dest))
  		return NET_RX_DROP;
  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))
  		return NET_RX_DROP;
  
  	/* create a copy of the skb, if needed, to modify it. */
  	if (skb_cow(skb, 0) < 0)
  		return NET_RX_DROP;
  
  	/* keep skb linear */
  	if (skb_linearize(skb) < 0)
  		return NET_RX_DROP;
  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);

  	bat_ogm_receive(ethhdr, skb->data, skb_headlen(skb), hard_iface);

  
  	kfree_skb(skb);
  	return NET_RX_SUCCESS;
  }
  
  static int recv_my_icmp_packet(struct bat_priv *bat_priv,
  			       struct sk_buff *skb, size_t icmp_len)
  {

  	struct hard_iface *primary_if = NULL;

  	struct orig_node *orig_node = NULL;

  	struct neigh_node *router = NULL;

  	struct icmp_packet_rr *icmp_packet;

  	int ret = NET_RX_DROP;

  
  	icmp_packet = (struct icmp_packet_rr *)skb->data;

  
  	/* add data to device queue */
  	if (icmp_packet->msg_type != ECHO_REQUEST) {
  		bat_socket_receive_packet(icmp_packet, icmp_len);

  		goto out;

  	}

  	primary_if = primary_if_get_selected(bat_priv);
  	if (!primary_if)

  		goto out;

  
  	/* answer echo request (ping) */
  	/* get routing information */

  	orig_node = orig_hash_find(bat_priv, icmp_packet->orig);

  	if (!orig_node)

  		goto out;

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

  	/* create a copy of the skb, if needed, to modify it. */
  	if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
  		goto out;
  
  	icmp_packet = (struct icmp_packet_rr *)skb->data;
  
  	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);

  	memcpy(icmp_packet->orig, primary_if->net_dev->dev_addr, ETH_ALEN);

  	icmp_packet->msg_type = ECHO_REPLY;
  	icmp_packet->ttl = TTL;

  	send_skb_packet(skb, router->if_incoming, router->addr);

  	ret = NET_RX_SUCCESS;

  out:

  	if (primary_if)
  		hardif_free_ref(primary_if);

  	if (router)
  		neigh_node_free_ref(router);

  	if (orig_node)

  		orig_node_free_ref(orig_node);

  	return ret;
  }
  
  static int recv_icmp_ttl_exceeded(struct bat_priv *bat_priv,

  				  struct sk_buff *skb)

  {

  	struct hard_iface *primary_if = NULL;

  	struct orig_node *orig_node = NULL;

  	struct neigh_node *router = NULL;

  	struct icmp_packet *icmp_packet;

  	int ret = NET_RX_DROP;

  
  	icmp_packet = (struct icmp_packet *)skb->data;

  
  	/* send TTL exceeded if packet is an echo request (traceroute) */
  	if (icmp_packet->msg_type != ECHO_REQUEST) {
  		pr_debug("Warning - can't forward icmp packet from %pM to "
  			 "%pM: ttl exceeded
  ", icmp_packet->orig,
  			 icmp_packet->dst);

  		goto out;

  	}

  	primary_if = primary_if_get_selected(bat_priv);
  	if (!primary_if)

  		goto out;

  
  	/* get routing information */

  	orig_node = orig_hash_find(bat_priv, icmp_packet->orig);

  	if (!orig_node)

  		goto out;

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

  	/* create a copy of the skb, if needed, to modify it. */
  	if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
  		goto out;

  	icmp_packet = (struct icmp_packet *)skb->data;

  	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);

  	memcpy(icmp_packet->orig, primary_if->net_dev->dev_addr, ETH_ALEN);

  	icmp_packet->msg_type = TTL_EXCEEDED;
  	icmp_packet->ttl = TTL;

  	send_skb_packet(skb, router->if_incoming, router->addr);

  	ret = NET_RX_SUCCESS;

  out:

  	if (primary_if)
  		hardif_free_ref(primary_if);

  	if (router)
  		neigh_node_free_ref(router);

  	if (orig_node)

  		orig_node_free_ref(orig_node);

  	return ret;
  }

  int recv_icmp_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);
  	struct icmp_packet_rr *icmp_packet;
  	struct ethhdr *ethhdr;

  	struct orig_node *orig_node = NULL;

  	struct neigh_node *router = NULL;

  	int hdr_size = sizeof(struct icmp_packet);

  	int ret = NET_RX_DROP;

  
  	/**
  	 * we truncate all incoming icmp packets if they don't match our size
  	 */
  	if (skb->len >= sizeof(struct icmp_packet_rr))
  		hdr_size = sizeof(struct icmp_packet_rr);
  
  	/* drop packet if it has not necessary minimum size */
  	if (unlikely(!pskb_may_pull(skb, hdr_size)))

  		goto out;

  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with unicast indication but broadcast recipient */
  	if (is_broadcast_ether_addr(ethhdr->h_dest))

  		goto out;

  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))

  		goto out;

  
  	/* not for me */
  	if (!is_my_mac(ethhdr->h_dest))

  		goto out;

  
  	icmp_packet = (struct icmp_packet_rr *)skb->data;
  
  	/* add record route information if not full */
  	if ((hdr_size == sizeof(struct icmp_packet_rr)) &&
  	    (icmp_packet->rr_cur < BAT_RR_LEN)) {
  		memcpy(&(icmp_packet->rr[icmp_packet->rr_cur]),
  			ethhdr->h_dest, ETH_ALEN);
  		icmp_packet->rr_cur++;
  	}
  
  	/* packet for me */
  	if (is_my_mac(icmp_packet->dst))
  		return recv_my_icmp_packet(bat_priv, skb, hdr_size);
  
  	/* TTL exceeded */
  	if (icmp_packet->ttl < 2)

  		return recv_icmp_ttl_exceeded(bat_priv, skb);

  	/* get routing information */

  	orig_node = orig_hash_find(bat_priv, icmp_packet->dst);

  	if (!orig_node)

  		goto out;

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

  	/* create a copy of the skb, if needed, to modify it. */
  	if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
  		goto out;

  	icmp_packet = (struct icmp_packet_rr *)skb->data;

  	/* decrement ttl */
  	icmp_packet->ttl--;
  
  	/* route it */

  	send_skb_packet(skb, router->if_incoming, router->addr);

  	ret = NET_RX_SUCCESS;

  out:

  	if (router)
  		neigh_node_free_ref(router);

  	if (orig_node)

  		orig_node_free_ref(orig_node);

  	return ret;
  }

  /* In the bonding case, send the packets in a round
   * robin fashion over the remaining interfaces.
   *
   * This method rotates the bonding list and increases the
   * returned router's refcount. */
  static struct neigh_node *find_bond_router(struct orig_node *primary_orig,

  					   const struct hard_iface *recv_if)

  {
  	struct neigh_node *tmp_neigh_node;
  	struct neigh_node *router = NULL, *first_candidate = NULL;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(tmp_neigh_node, &primary_orig->bond_list,
  				bonding_list) {
  		if (!first_candidate)
  			first_candidate = tmp_neigh_node;
  
  		/* recv_if == NULL on the first node. */
  		if (tmp_neigh_node->if_incoming == recv_if)
  			continue;
  
  		if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
  			continue;
  
  		router = tmp_neigh_node;
  		break;
  	}
  
  	/* use the first candidate if nothing was found. */
  	if (!router && first_candidate &&
  	    atomic_inc_not_zero(&first_candidate->refcount))
  		router = first_candidate;
  
  	if (!router)
  		goto out;
  
  	/* selected should point to the next element
  	 * after the current router */
  	spin_lock_bh(&primary_orig->neigh_list_lock);
  	/* this is a list_move(), which unfortunately
  	 * does not exist as rcu version */
  	list_del_rcu(&primary_orig->bond_list);
  	list_add_rcu(&primary_orig->bond_list,
  		     &router->bonding_list);
  	spin_unlock_bh(&primary_orig->neigh_list_lock);
  
  out:
  	rcu_read_unlock();
  	return router;
  }
  
  /* Interface Alternating: Use the best of the
   * remaining candidates which are not using
   * this interface.
   *
   * Increases the returned router's refcount */
  static struct neigh_node *find_ifalter_router(struct orig_node *primary_orig,

  					      const struct hard_iface *recv_if)

  {
  	struct neigh_node *tmp_neigh_node;
  	struct neigh_node *router = NULL, *first_candidate = NULL;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(tmp_neigh_node, &primary_orig->bond_list,
  				bonding_list) {
  		if (!first_candidate)
  			first_candidate = tmp_neigh_node;
  
  		/* recv_if == NULL on the first node. */
  		if (tmp_neigh_node->if_incoming == recv_if)
  			continue;
  
  		if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
  			continue;
  
  		/* if we don't have a router yet
  		 * or this one is better, choose it. */
  		if ((!router) ||
  		    (tmp_neigh_node->tq_avg > router->tq_avg)) {
  			/* decrement refcount of
  			 * previously selected router */
  			if (router)
  				neigh_node_free_ref(router);
  
  			router = tmp_neigh_node;
  			atomic_inc_not_zero(&router->refcount);
  		}
  
  		neigh_node_free_ref(tmp_neigh_node);
  	}
  
  	/* use the first candidate if nothing was found. */
  	if (!router && first_candidate &&
  	    atomic_inc_not_zero(&first_candidate->refcount))
  		router = first_candidate;
  
  	rcu_read_unlock();
  	return router;
  }

  int recv_tt_query(struct sk_buff *skb, struct hard_iface *recv_if)
  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);
  	struct tt_query_packet *tt_query;

  	uint16_t tt_len;

  	struct ethhdr *ethhdr;
  
  	/* drop packet if it has not necessary minimum size */
  	if (unlikely(!pskb_may_pull(skb, sizeof(struct tt_query_packet))))
  		goto out;
  
  	/* I could need to modify it */
  	if (skb_cow(skb, sizeof(struct tt_query_packet)) < 0)
  		goto out;
  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with unicast indication but broadcast recipient */
  	if (is_broadcast_ether_addr(ethhdr->h_dest))
  		goto out;
  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))
  		goto out;
  
  	tt_query = (struct tt_query_packet *)skb->data;
  
  	tt_query->tt_data = ntohs(tt_query->tt_data);
  
  	switch (tt_query->flags & TT_QUERY_TYPE_MASK) {
  	case TT_REQUEST:
  		/* If we cannot provide an answer the tt_request is
  		 * forwarded */
  		if (!send_tt_response(bat_priv, tt_query)) {
  			bat_dbg(DBG_TT, bat_priv,
  				"Routing TT_REQUEST to %pM [%c]
  ",
  				tt_query->dst,
  				(tt_query->flags & TT_FULL_TABLE ? 'F' : '.'));
  			tt_query->tt_data = htons(tt_query->tt_data);
  			return route_unicast_packet(skb, recv_if);
  		}
  		break;
  	case TT_RESPONSE:

  		if (is_my_mac(tt_query->dst)) {
  			/* packet needs to be linearized to access the TT
  			 * changes */
  			if (skb_linearize(skb) < 0)
  				goto out;

  			tt_len = tt_query->tt_data * sizeof(struct tt_change);
  
  			/* Ensure we have all the claimed data */
  			if (unlikely(skb_headlen(skb) <

  				     sizeof(struct tt_query_packet) + tt_len))

  				goto out;

  			handle_tt_response(bat_priv, tt_query);

  		} else {

  			bat_dbg(DBG_TT, bat_priv,
  				"Routing TT_RESPONSE to %pM [%c]
  ",
  				tt_query->dst,
  				(tt_query->flags & TT_FULL_TABLE ? 'F' : '.'));
  			tt_query->tt_data = htons(tt_query->tt_data);
  			return route_unicast_packet(skb, recv_if);
  		}
  		break;
  	}
  
  out:
  	/* returning NET_RX_DROP will make the caller function kfree the skb */
  	return NET_RX_DROP;
  }

  int recv_roam_adv(struct sk_buff *skb, struct hard_iface *recv_if)
  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);
  	struct roam_adv_packet *roam_adv_packet;
  	struct orig_node *orig_node;
  	struct ethhdr *ethhdr;
  
  	/* drop packet if it has not necessary minimum size */
  	if (unlikely(!pskb_may_pull(skb, sizeof(struct roam_adv_packet))))
  		goto out;
  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with unicast indication but broadcast recipient */
  	if (is_broadcast_ether_addr(ethhdr->h_dest))
  		goto out;
  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))
  		goto out;
  
  	roam_adv_packet = (struct roam_adv_packet *)skb->data;
  
  	if (!is_my_mac(roam_adv_packet->dst))
  		return route_unicast_packet(skb, recv_if);
  
  	orig_node = orig_hash_find(bat_priv, roam_adv_packet->src);
  	if (!orig_node)
  		goto out;
  
  	bat_dbg(DBG_TT, bat_priv, "Received ROAMING_ADV from %pM "
  		"(client %pM)
  ", roam_adv_packet->src,
  		roam_adv_packet->client);
  
  	tt_global_add(bat_priv, orig_node, roam_adv_packet->client,

  		      atomic_read(&orig_node->last_ttvn) + 1, true, false);

  
  	/* Roaming phase starts: I have new information but the ttvn has not
  	 * been incremented yet. This flag will make me check all the incoming
  	 * packets for the correct destination. */
  	bat_priv->tt_poss_change = true;
  
  	orig_node_free_ref(orig_node);
  out:
  	/* returning NET_RX_DROP will make the caller function kfree the skb */
  	return NET_RX_DROP;
  }

  /* find a suitable router for this originator, and use

   * bonding if possible. increases the found neighbors
   * refcount.*/

  struct neigh_node *find_router(struct bat_priv *bat_priv,
  			       struct orig_node *orig_node,

  			       const struct hard_iface *recv_if)

  {
  	struct orig_node *primary_orig_node;
  	struct orig_node *router_orig;

  	struct neigh_node *router;

  	static uint8_t zero_mac[ETH_ALEN] = {0, 0, 0, 0, 0, 0};
  	int bonding_enabled;
  
  	if (!orig_node)
  		return NULL;

  	router = orig_node_get_router(orig_node);
  	if (!router)

  		goto err;

  
  	/* without bonding, the first node should
  	 * always choose the default router. */

  	bonding_enabled = atomic_read(&bat_priv->bonding);

  	rcu_read_lock();
  	/* select default router to output */

  	router_orig = router->orig_node;

  	if (!router_orig)
  		goto err_unlock;

  	if ((!recv_if) && (!bonding_enabled))
  		goto return_router;

  
  	/* if we have something in the primary_addr, we can search
  	 * for a potential bonding candidate. */

  	if (compare_eth(router_orig->primary_addr, zero_mac))

  		goto return_router;

  
  	/* find the orig_node which has the primary interface. might
  	 * even be the same as our router_orig in many cases */

  	if (compare_eth(router_orig->primary_addr, router_orig->orig)) {

  		primary_orig_node = router_orig;
  	} else {

  		primary_orig_node = orig_hash_find(bat_priv,
  						   router_orig->primary_addr);

  		if (!primary_orig_node)

  			goto return_router;

  		orig_node_free_ref(primary_orig_node);

  	}
  
  	/* with less than 2 candidates, we can't do any
  	 * bonding and prefer the original router. */

  	if (atomic_read(&primary_orig_node->bond_candidates) < 2)
  		goto return_router;

  	/* all nodes between should choose a candidate which
  	 * is is not on the interface where the packet came
  	 * in. */

  	neigh_node_free_ref(router);

  	if (bonding_enabled)
  		router = find_bond_router(primary_orig_node, recv_if);
  	else
  		router = find_ifalter_router(primary_orig_node, recv_if);

  return_router:

  	if (router && router->if_incoming->if_status != IF_ACTIVE)
  		goto err_unlock;

  	rcu_read_unlock();

  	return router;

  err_unlock:
  	rcu_read_unlock();
  err:
  	if (router)
  		neigh_node_free_ref(router);
  	return NULL;

  }
  
  static int check_unicast_packet(struct sk_buff *skb, int hdr_size)
  {
  	struct ethhdr *ethhdr;
  
  	/* drop packet if it has not necessary minimum size */
  	if (unlikely(!pskb_may_pull(skb, hdr_size)))
  		return -1;
  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with unicast indication but broadcast recipient */
  	if (is_broadcast_ether_addr(ethhdr->h_dest))
  		return -1;
  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))
  		return -1;
  
  	/* not for me */
  	if (!is_my_mac(ethhdr->h_dest))
  		return -1;
  
  	return 0;
  }

  int route_unicast_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);

  	struct orig_node *orig_node = NULL;
  	struct neigh_node *neigh_node = NULL;

  	struct unicast_packet *unicast_packet;
  	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);

  	int ret = NET_RX_DROP;

  	struct sk_buff *new_skb;
  
  	unicast_packet = (struct unicast_packet *)skb->data;
  
  	/* TTL exceeded */
  	if (unicast_packet->ttl < 2) {
  		pr_debug("Warning - can't forward unicast packet from %pM to "
  			 "%pM: ttl exceeded
  ", ethhdr->h_source,
  			 unicast_packet->dest);

  		goto out;

  	}
  
  	/* get routing information */

  	orig_node = orig_hash_find(bat_priv, unicast_packet->dest);

  	if (!orig_node)

  		goto out;

  	/* find_router() increases neigh_nodes refcount if found. */

  	neigh_node = find_router(bat_priv, orig_node, recv_if);

  	if (!neigh_node)

  		goto out;

  
  	/* create a copy of the skb, if needed, to modify it. */
  	if (skb_cow(skb, sizeof(struct ethhdr)) < 0)

  		goto out;

  
  	unicast_packet = (struct unicast_packet *)skb->data;
  
  	if (unicast_packet->packet_type == BAT_UNICAST &&
  	    atomic_read(&bat_priv->fragmentation) &&

  	    skb->len > neigh_node->if_incoming->net_dev->mtu) {
  		ret = frag_send_skb(skb, bat_priv,
  				    neigh_node->if_incoming, neigh_node->addr);
  		goto out;
  	}

  
  	if (unicast_packet->packet_type == BAT_UNICAST_FRAG &&

  	    frag_can_reassemble(skb, neigh_node->if_incoming->net_dev->mtu)) {

  
  		ret = frag_reassemble_skb(skb, bat_priv, &new_skb);
  
  		if (ret == NET_RX_DROP)

  			goto out;

  
  		/* packet was buffered for late merge */

  		if (!new_skb) {
  			ret = NET_RX_SUCCESS;
  			goto out;
  		}

  
  		skb = new_skb;
  		unicast_packet = (struct unicast_packet *)skb->data;
  	}
  
  	/* decrement ttl */
  	unicast_packet->ttl--;
  
  	/* route it */

  	send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);

  	ret = NET_RX_SUCCESS;

  out:
  	if (neigh_node)
  		neigh_node_free_ref(neigh_node);
  	if (orig_node)

  		orig_node_free_ref(orig_node);

  	return ret;

  }

  static int check_unicast_ttvn(struct bat_priv *bat_priv,
  			       struct sk_buff *skb) {
  	uint8_t curr_ttvn;
  	struct orig_node *orig_node;
  	struct ethhdr *ethhdr;
  	struct hard_iface *primary_if;
  	struct unicast_packet *unicast_packet;

  	bool tt_poss_change;

  
  	/* I could need to modify it */
  	if (skb_cow(skb, sizeof(struct unicast_packet)) < 0)
  		return 0;
  
  	unicast_packet = (struct unicast_packet *)skb->data;

  	if (is_my_mac(unicast_packet->dest)) {
  		tt_poss_change = bat_priv->tt_poss_change;

  		curr_ttvn = (uint8_t)atomic_read(&bat_priv->ttvn);

  	} else {

  		orig_node = orig_hash_find(bat_priv, unicast_packet->dest);
  
  		if (!orig_node)
  			return 0;
  
  		curr_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);

  		tt_poss_change = orig_node->tt_poss_change;

  		orig_node_free_ref(orig_node);
  	}
  
  	/* Check whether I have to reroute the packet */

  	if (seq_before(unicast_packet->ttvn, curr_ttvn) || tt_poss_change) {

  		/* Linearize the skb before accessing it */
  		if (skb_linearize(skb) < 0)
  			return 0;
  
  		ethhdr = (struct ethhdr *)(skb->data +
  			sizeof(struct unicast_packet));

  		orig_node = transtable_search(bat_priv, NULL, ethhdr->h_dest);

  
  		if (!orig_node) {
  			if (!is_my_client(bat_priv, ethhdr->h_dest))
  				return 0;
  			primary_if = primary_if_get_selected(bat_priv);
  			if (!primary_if)
  				return 0;
  			memcpy(unicast_packet->dest,
  			       primary_if->net_dev->dev_addr, ETH_ALEN);
  			hardif_free_ref(primary_if);
  		} else {
  			memcpy(unicast_packet->dest, orig_node->orig,
  			       ETH_ALEN);
  			curr_ttvn = (uint8_t)
  				atomic_read(&orig_node->last_ttvn);
  			orig_node_free_ref(orig_node);
  		}
  
  		bat_dbg(DBG_ROUTES, bat_priv, "TTVN mismatch (old_ttvn %u "
  			"new_ttvn %u)! Rerouting unicast packet (for %pM) to "
  			"%pM
  ", unicast_packet->ttvn, curr_ttvn,
  			ethhdr->h_dest, unicast_packet->dest);
  
  		unicast_packet->ttvn = curr_ttvn;
  	}
  	return 1;
  }

  int recv_unicast_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {

  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);

  	struct unicast_packet *unicast_packet;

  	int hdr_size = sizeof(*unicast_packet);

  
  	if (check_unicast_packet(skb, hdr_size) < 0)
  		return NET_RX_DROP;

  	if (!check_unicast_ttvn(bat_priv, skb))
  		return NET_RX_DROP;

  	unicast_packet = (struct unicast_packet *)skb->data;
  
  	/* packet for me */
  	if (is_my_mac(unicast_packet->dest)) {
  		interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size);
  		return NET_RX_SUCCESS;
  	}

  	return route_unicast_packet(skb, recv_if);

  }

  int recv_ucast_frag_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);
  	struct unicast_frag_packet *unicast_packet;

  	int hdr_size = sizeof(*unicast_packet);

  	struct sk_buff *new_skb = NULL;
  	int ret;
  
  	if (check_unicast_packet(skb, hdr_size) < 0)
  		return NET_RX_DROP;

  	if (!check_unicast_ttvn(bat_priv, skb))
  		return NET_RX_DROP;

  	unicast_packet = (struct unicast_frag_packet *)skb->data;
  
  	/* packet for me */
  	if (is_my_mac(unicast_packet->dest)) {
  
  		ret = frag_reassemble_skb(skb, bat_priv, &new_skb);
  
  		if (ret == NET_RX_DROP)
  			return NET_RX_DROP;
  
  		/* packet was buffered for late merge */
  		if (!new_skb)
  			return NET_RX_SUCCESS;
  
  		interface_rx(recv_if->soft_iface, new_skb, recv_if,
  			     sizeof(struct unicast_packet));
  		return NET_RX_SUCCESS;
  	}

  	return route_unicast_packet(skb, recv_if);

  }

  int recv_bcast_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);

  	struct orig_node *orig_node = NULL;

  	struct bcast_packet *bcast_packet;
  	struct ethhdr *ethhdr;

  	int hdr_size = sizeof(*bcast_packet);

  	int ret = NET_RX_DROP;

  	int32_t seq_diff;
  
  	/* drop packet if it has not necessary minimum size */
  	if (unlikely(!pskb_may_pull(skb, hdr_size)))

  		goto out;

  
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* packet with broadcast indication but unicast recipient */
  	if (!is_broadcast_ether_addr(ethhdr->h_dest))

  		goto out;

  
  	/* packet with broadcast sender address */
  	if (is_broadcast_ether_addr(ethhdr->h_source))

  		goto out;

  
  	/* ignore broadcasts sent by myself */
  	if (is_my_mac(ethhdr->h_source))

  		goto out;

  
  	bcast_packet = (struct bcast_packet *)skb->data;
  
  	/* ignore broadcasts originated by myself */
  	if (is_my_mac(bcast_packet->orig))

  		goto out;

  
  	if (bcast_packet->ttl < 2)

  		goto out;

  	orig_node = orig_hash_find(bat_priv, bcast_packet->orig);

  
  	if (!orig_node)

  		goto out;

  	spin_lock_bh(&orig_node->bcast_seqno_lock);

  
  	/* check whether the packet is a duplicate */

  	if (get_bit_status(orig_node->bcast_bits, orig_node->last_bcast_seqno,
  			   ntohl(bcast_packet->seqno)))
  		goto spin_unlock;

  
  	seq_diff = ntohl(bcast_packet->seqno) - orig_node->last_bcast_seqno;
  
  	/* check whether the packet is old and the host just restarted. */
  	if (window_protected(bat_priv, seq_diff,

  			     &orig_node->bcast_seqno_reset))
  		goto spin_unlock;

  
  	/* mark broadcast in flood history, update window position
  	 * if required. */
  	if (bit_get_packet(bat_priv, orig_node->bcast_bits, seq_diff, 1))
  		orig_node->last_bcast_seqno = ntohl(bcast_packet->seqno);

  	spin_unlock_bh(&orig_node->bcast_seqno_lock);

  	/* rebroadcast packet */

  	add_bcast_packet_to_list(bat_priv, skb, 1);

  
  	/* broadcast for me */
  	interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size);

  	ret = NET_RX_SUCCESS;
  	goto out;

  spin_unlock:
  	spin_unlock_bh(&orig_node->bcast_seqno_lock);

  out:
  	if (orig_node)

  		orig_node_free_ref(orig_node);

  	return ret;

  }

  int recv_vis_packet(struct sk_buff *skb, struct hard_iface *recv_if)

  {
  	struct vis_packet *vis_packet;
  	struct ethhdr *ethhdr;
  	struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);

  	int hdr_size = sizeof(*vis_packet);

  
  	/* keep skb linear */
  	if (skb_linearize(skb) < 0)
  		return NET_RX_DROP;
  
  	if (unlikely(!pskb_may_pull(skb, hdr_size)))
  		return NET_RX_DROP;
  
  	vis_packet = (struct vis_packet *)skb->data;
  	ethhdr = (struct ethhdr *)skb_mac_header(skb);
  
  	/* not for me */
  	if (!is_my_mac(ethhdr->h_dest))
  		return NET_RX_DROP;
  
  	/* ignore own packets */
  	if (is_my_mac(vis_packet->vis_orig))
  		return NET_RX_DROP;
  
  	if (is_my_mac(vis_packet->sender_orig))
  		return NET_RX_DROP;
  
  	switch (vis_packet->vis_type) {
  	case VIS_TYPE_SERVER_SYNC:
  		receive_server_sync_packet(bat_priv, vis_packet,
  					   skb_headlen(skb));
  		break;
  
  	case VIS_TYPE_CLIENT_UPDATE:
  		receive_client_update_packet(bat_priv, vis_packet,
  					     skb_headlen(skb));
  		break;
  
  	default:	/* ignore unknown packet */
  		break;
  	}
  
  	/* We take a copy of the data in the packet, so we should
  	   always free the skbuf. */
  	return NET_RX_DROP;
  }