path: root/net/batman-adv/distributed-arp-table.c

/* Copyright (C) 2011-2012 B.A.T.M.A.N. contributors:
 *
 * Antonio Quartulli
 *
 * 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 <linux/if_ether.h>
#include <linux/if_arp.h>
#include <net/arp.h>

#include "main.h"
#include "hash.h"
#include "distributed-arp-table.h"
#include "hard-interface.h"
#include "originator.h"
#include "send.h"
#include "types.h"
#include "translation-table.h"
#include "unicast.h"

static void batadv_dat_purge(struct work_struct *work);

/**
 * batadv_dat_start_timer - initialise the DAT periodic worker
 * @bat_priv: the bat priv with all the soft interface information
 */
static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
{
	INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
	queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
			   msecs_to_jiffies(10000));
}

/**
 * batadv_dat_entry_free_ref - decrements the dat_entry refcounter and possibly
 * free it
 * @dat_entry: the oentry to free
 */
static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
{
	if (atomic_dec_and_test(&dat_entry->refcount))
		kfree_rcu(dat_entry, rcu);
}

/**
 * batadv_dat_to_purge - checks whether a dat_entry has to be purged or not
 * @dat_entry: the entry to check
 *
 * Returns true if the entry has to be purged now, false otherwise
 */
static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
{
	return batadv_has_timed_out(dat_entry->last_update,
				    BATADV_DAT_ENTRY_TIMEOUT);
}

/**
 * __batadv_dat_purge - delete entries from the DAT local storage
 * @bat_priv: the bat priv with all the soft interface information
 * @to_purge: function in charge to decide whether an entry has to be purged or
 *	      not. This function takes the dat_entry as argument and has to
 *	      returns a boolean value: true is the entry has to be deleted,
 *	      false otherwise
 *
 * Loops over each entry in the DAT local storage and delete it if and only if
 * the to_purge function passed as argument returns true
 */
static void __batadv_dat_purge(struct batadv_priv *bat_priv,
			       bool (*to_purge)(struct batadv_dat_entry *))
{
	spinlock_t *list_lock; /* protects write access to the hash lists */
	struct batadv_dat_entry *dat_entry;
	struct hlist_node *node, *node_tmp;
	struct hlist_head *head;
	uint32_t i;

	if (!bat_priv->dat.hash)
		return;

	for (i = 0; i < bat_priv->dat.hash->size; i++) {
		head = &bat_priv->dat.hash->table[i];
		list_lock = &bat_priv->dat.hash->list_locks[i];

		spin_lock_bh(list_lock);
		hlist_for_each_entry_safe(dat_entry, node, node_tmp, head,
					  hash_entry) {
			/* if an helper function has been passed as parameter,
			 * ask it if the entry has to be purged or not
			 */
			if (to_purge && !to_purge(dat_entry))
				continue;

			hlist_del_rcu(node);
			batadv_dat_entry_free_ref(dat_entry);
		}
		spin_unlock_bh(list_lock);
	}
}

/**
 * batadv_dat_purge - periodic task that deletes old entries from the local DAT
 * hash table
 * @work: kernel work struct
 */
static void batadv_dat_purge(struct work_struct *work)
{
	struct delayed_work *delayed_work;
	struct batadv_priv_dat *priv_dat;
	struct batadv_priv *bat_priv;

	delayed_work = container_of(work, struct delayed_work, work);
	priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
	bat_priv = container_of(priv_dat, struct batadv_priv, dat);

	__batadv_dat_purge(bat_priv, batadv_dat_to_purge);
	batadv_dat_start_timer(bat_priv);
}

/**
 * batadv_compare_dat - comparing function used in the local DAT hash table
 * @node: node in the local table
 * @data2: second object to compare the node to
 *
 * Returns 1 if the two entry are the same, 0 otherwise
 */
static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
{
	const void *data1 = container_of(node, struct batadv_dat_entry,
					 hash_entry);

	return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
}

/**
 * batadv_arp_hw_src - extract the hw_src field from an ARP packet
 * @skb: ARP packet
 * @hdr_size: size of the possible header before the ARP packet
 *
 * Returns the value of the hw_src field in the ARP packet
 */
static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
{
	uint8_t *addr;

	addr = (uint8_t *)(skb->data