net/batman-adv/bridge_loop_avoidance.c

/*
 * Copyright (C) 2011 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 "hash.h"
#include "hard-interface.h"
#include "originator.h"
#include "bridge_loop_avoidance.h"
#include "translation-table.h"
#include "send.h"

#include <linux/etherdevice.h>
#include <linux/crc16.h>
#include <linux/if_arp.h>
#include <net/arp.h>
#include <linux/if_vlan.h>

static const uint8_t claim_dest[6] = {0xff, 0x43, 0x05, 0x00, 0x00, 0x00};
static const uint8_t announce_mac[4] = {0x43, 0x05, 0x43, 0x05};

static void bla_periodic_work(struct work_struct *work);
static void bla_send_announce(struct bat_priv *bat_priv,
			      struct backbone_gw *backbone_gw);

/* return the index of the claim */
static inline uint32_t choose_claim(const void *data, uint32_t size)
{
	const unsigned char *key = data;
	uint32_t hash = 0;
	size_t i;

	for (i = 0; i < ETH_ALEN + sizeof(short); i++) {
		hash += key[i];
		hash += (hash << 10);
		hash ^= (hash >> 6);
	}

	hash += (hash << 3);
	hash ^= (hash >> 11);
	hash += (hash << 15);

	return hash % size;
}

/* return the index of the backbone gateway */
static inline uint32_t choose_backbone_gw(const void *data, uint32_t size)
{
	const unsigned char *key = data;
	uint32_t hash = 0;
	size_t i;

	for (i = 0; i < ETH_ALEN + sizeof(short); i++) {
		hash += key[i];
		hash += (hash << 10);
		hash ^= (hash >> 6);
	}

	hash += (hash << 3);
	hash ^= (hash >> 11);
	hash += (hash << 15);

	return hash % size;
}


/* compares address and vid of two backbone gws */
static int compare_backbone_gw(const struct hlist_node *node, const void *data2)
{
	const void *data1 = container_of(node, struct backbone_gw,
					 hash_entry);

	return (memcmp(data1, data2, ETH_ALEN + sizeof(short)) == 0 ? 1 : 0);
}

/* compares address and vid of two claims */
static int compare_claim(const struct hlist_node *node, const void *data2)
{
	const void *data1 = container_of(node, struct claim,
					 hash_entry);

	return (memcmp(data1, data2, ETH_ALEN + sizeof(short)) == 0 ? 1 : 0);
}

/* free a backbone gw */
static void backbone_gw_free_ref(struct backbone_gw *backbone_gw)
{
	if (atomic_dec_and_test(&backbone_gw->refcount))
		kfree_rcu(backbone_gw, rcu);
}

/* finally deinitialize the claim */
static void claim_free_rcu(struct rcu_head *rcu)
{
	struct claim *claim;

	claim = container_of(rcu, struct claim, rcu);

	backbone_gw_free_ref(claim->backbone_gw);
	kfree(claim);
}

/* free a claim, call claim_free_rcu if its the last reference */
static void claim_free_ref(struct claim *claim)
{
	if (atomic_dec_and_test(&claim->refcount))
		call_rcu(&claim->rcu, claim_free_rcu);
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @data: search data (may be local/static data)
 *
 * looks for a claim in the hash, and returns it if found
 * or NULL otherwise.
 */
static struct claim *claim_hash_find(struct bat_priv *bat_priv,
				     struct claim *data)
{
	struct hashtable_t *hash = bat_priv->claim_hash;
	struct hlist_head *head;
	struct hlist_node *node;
	struct claim *claim;
	struct claim *claim_tmp = NULL;
	int index;

	if (!hash)
		return NULL;

	index = choose_claim(data, hash->size);
	head = &hash->table[index];

	rcu_read_lock();
	hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
		if (!compare_claim(&claim->hash_entry, data))
			continue;

		if (!atomic_inc_not_zero(&claim->refcount))
			continue;

		claim_tmp = claim;
		break;
	}
	rcu_read_unlock();

	return claim_tmp;
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: the address of the originator
 * @vid: the VLAN ID
 *
 * looks for a claim in the hash, and returns it if found
 * or NULL otherwise.
 */
static struct backbone_gw *backbone_hash_find(struct bat_priv *bat_priv,
					      uint8_t *addr, short vid)
{
	struct hashtable_t *hash = bat_priv->backbone_hash;
	struct hlist_head *head;
	struct hlist_node *node;
	struct backbone_gw search_entry, *backbone_gw;
	struct backbone_gw *backbone_gw_tmp = NULL;
	int index;

	if (!hash)
		return NULL;

	memcpy(search_entry.orig, addr, ETH_ALEN);
	search_entry.vid = vid;

	index = choose_backbone_gw(&search_entry, hash->size);
	head = &hash->table[index];

	rcu_read_lock();
	hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
		if (!compare_backbone_gw(&backbone_gw->hash_entry,
					 &search_entry))
			continue;

		if (!atomic_inc_not_zero(&backbone_gw->refcount))
			continue;

		backbone_gw_tmp = backbone_gw;
		break;
	}
	rcu_read_unlock();

	return backbone_gw_tmp;
}

/* delete all claims for a backbone */
static void bla_del_backbone_claims(struct backbone_gw *backbone_gw)
{
	struct hashtable_t *hash;
	struct hlist_node *node, *node_tmp;
	struct hlist_head *head;
	struct claim *claim;
	int i;
	spinlock_t *list_lock;	/* protects write access to the hash lists */

	hash = backbone_gw->bat_priv->claim_hash;
	if (!hash)
		return;

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

		spin_lock_bh(list_lock);
		hlist_for_each_entry_safe(claim, node, node_tmp,
					  head, hash_entry) {

			if (claim->backbone_gw != backbone_gw)
				continue;

			claim_free_ref(claim);
			hlist_del_rcu(node);
		}
		spin_unlock_bh(list_lock);
	}

	/* all claims gone, intialize CRC */
	backbone_gw->crc = BLA_CRC_INIT;
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the mac address to be announced within the claim
 * @vid: the VLAN ID
 * @claimtype: the type of the claim (CLAIM, UNCLAIM, ANNOUNCE, ...)
 *
 * sends a claim frame according to the provided info.
 */
static void bla_send_claim(struct bat_priv *bat_priv, uint8_t *mac,
			   short vid, int claimtype)
{
	struct sk_buff *skb;
	struct ethhdr *ethhdr;
	struct hard_iface *primary_if;
	struct net_device *soft_iface;
	uint8_t *hw_src;
	struct bla_claim_dst local_claim_dest;
	uint32_t zeroip = 0;

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

	memcpy(&local_claim_dest, claim_dest, sizeof(local_claim_dest));
	local_claim_dest.type = claimtype;

	soft_iface = primary_if->soft_iface;

	skb = arp_create(ARPOP_REPLY, ETH_P_ARP,
			 /* IP DST: 0.0.0.0 */
			 zeroip,
			 primary_if->soft_iface,
			 /* IP SRC: 0.0.0.0 */
			 zeroip,
			 /* Ethernet DST: Broadcast */
			 NULL,
			 /* Ethernet SRC/HW SRC:  originator mac */
			 primary_if->net_dev->dev_addr,
			 /* HW DST: FF:43:05:XX:00:00
			  * with XX   = claim type
			  */
			 (uint8_t *)&local_claim_dest);

	if (!skb)
		goto out;

	ethhdr = (struct ethhdr *)skb->data;
	hw_src = (uint8_t *)ethhdr +
		 sizeof(struct ethhdr) +
		 sizeof(struct arphdr);

	/* now we pretend that the client would have sent this ... */
	switch (claimtype) {
	case CLAIM_TYPE_ADD:
		/* normal claim frame
		 * set Ethernet SRC to the clients mac
		 */
		memcpy(ethhdr->h_source, mac, ETH_ALEN);
		bat_dbg(DBG_BLA, bat_priv,
			"bla_send_claim(): CLAIM %pM on vid %d\n", mac, vid);
		break;
	case CLAIM_TYPE_DEL:
		/* unclaim frame
		 * set HW SRC to the clients mac
		 */
		memcpy(hw_src, mac, ETH_ALEN);
		bat_dbg(DBG_BLA, bat_priv,
			"bla_send_claim(): UNCLAIM %pM on vid %d\n", mac, vid);
		break;
	case CLAIM_TYPE_ANNOUNCE:
		/* announcement frame
		 * set HW SRC to the special mac containg the crc
		 */
		memcpy(hw_src, mac, ETH_ALEN);
		bat_dbg(DBG_BLA, bat_priv,
			"bla_send_claim(): ANNOUNCE of %pM on vid %d\n",
			ethhdr->h_source, vid);
		break;
	case CLAIM_TYPE_REQUEST:
		/* request frame
		 * set HW SRC to the special mac containg the crc
		 */
		memcpy(hw_src, mac, ETH_ALEN);
		memcpy(ethhdr->h_dest, mac, ETH_ALEN);
		bat_dbg(DBG_BLA, bat_priv,
			"bla_send_claim(): REQUEST of %pM to %pMon vid %d\n",
			ethhdr->h_source, ethhdr->h_dest, vid);
		break;

	}

	if (vid != -1)
		skb = vlan_insert_tag(skb, vid);

	skb_reset_mac_header(skb);
	skb->protocol = eth_type_trans(skb, soft_iface);
	bat_priv->stats.rx_packets++;
	bat_priv->stats.rx_bytes += skb->len + sizeof(struct ethhdr);
	soft_iface->last_rx = jiffies;

	netif_rx(skb);
out:
	if (primary_if)
		hardif_free_ref(primary_if);
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the mac address of the originator
 * @vid: the VLAN ID
 *
 * searches for the backbone gw or creates a new one if it could not
 * be found.
 */
static struct backbone_gw *bla_get_backbone_gw(struct bat_priv *bat_priv,
					       uint8_t *orig, short vid)
{
	struct backbone_gw *entry;
	struct orig_node *orig_node;
	int hash_added;

	entry = backbone_hash_find(bat_priv, orig, vid);

	if (entry)
		return entry;

	bat_dbg(DBG_BLA, bat_priv,
		"bla_get_backbone_gw(): not found (%pM, %d), creating new entry\n",
		orig, vid);

	entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
	if (!entry)
		return NULL;

	entry->vid = vid;
	entry->lasttime = jiffies;
	entry->crc = BLA_CRC_INIT;
	entry->bat_priv = bat_priv;
	atomic_set(&entry->request_sent, 0);
	memcpy(entry->orig, orig, ETH_ALEN);

	/* one for the hash, one for returning */
	atomic_set(&entry->refcount, 2);

	hash_added = hash_add(bat_priv->backbone_hash, compare_backbone_gw,
			      choose_backbone_gw, entry, &entry->hash_entry);

	if (unlikely(hash_added != 0)) {
		/* hash failed, free the structure */
		kfree(entry);
		return NULL;
	}

	/* this is a gateway now, remove any tt entries */
	orig_node = orig_hash_find(bat_priv, orig);
	if (orig_node) {
		tt_global_del_orig(bat_priv, orig_node,
				   "became a backbone gateway");
		orig_node_free_ref(orig_node);
	}
	return entry;
}

/* update or add the own backbone gw to make sure we announce
 * where we receive other backbone gws
 */
static void bla_update_own_backbone_gw(struct bat_priv *bat_priv,
				       struct hard_iface *primary_if,
				       short vid)
{
	struct backbone_gw *backbone_gw;

	backbone_gw = bla_get_backbone_gw(bat_priv,
					  primary_if->net_dev->dev_addr, vid);
	if (unlikely(!backbone_gw))
		return;

	backbone_gw->lasttime = jiffies;
	backbone_gw_free_ref(backbone_gw);
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @vid: the vid where the request came on
 *
 * Repeat all of our own claims, and finally send an ANNOUNCE frame
 * to allow the requester another check if the CRC is correct now.
 */
static void bla_answer_request(struct bat_priv *bat_priv,
			       struct hard_iface *primary_if, short vid)
{
	struct hlist_node *node;
	struct hlist_head *head;
	struct hashtable_t *hash;
	struct claim *claim;
	struct backbone_gw *backbone_gw;
	int i;

	bat_dbg(DBG_BLA, bat_priv,
		"bla_answer_request(): received a claim request, send all of our own claims again\n");

	backbone_gw = backbone_hash_find(bat_priv,
					 primary_if->net_dev->dev_addr, vid);
	if (!backbone_gw)
		return;

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

		rcu_read_lock();
		hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
			/* only own claims are interesting */
			if (claim->backbone_gw != backbone_gw)
				continue;

			bla_send_claim(bat_priv, claim->addr, claim->vid,
				       CLAIM_TYPE_ADD);
		}
		rcu_read_unlock();
	}

	/* finally, send an announcement frame */
	bla_send_announce(bat_priv, backbone_gw);
	backbone_gw_free_ref(backbone_gw);
}

/**
 * @backbone_gw: the backbone gateway from whom we are out of sync
 *
 * When the crc is wrong, ask the backbone gateway for a full table update.
 * After the request, it will repeat all of his own claims and finally
 * send an announcement claim with which we can check again.
 */
static void bla_send_request(struct backbone_gw *backbone_gw)
{
	/* first, remove all old entries */
	bla_del_backbone_claims(backbone_gw);

	bat_dbg(DBG_BLA, backbone_gw->bat_priv,
		"Sending REQUEST to %pM\n",
		backbone_gw->orig);

	/* send request */
	bla_send_claim(backbone_gw->bat_priv, backbone_gw->orig,
		       backbone_gw->vid, CLAIM_TYPE_REQUEST);

	/* no local broadcasts should be sent or received, for now. */
	if (!atomic_read(&backbone_gw->request_sent)) {
		atomic_inc(&backbone_gw->bat_priv->bla_num_requests);
		atomic_set(&backbone_gw->request_sent, 1);
	}
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @backbone_gw: our backbone gateway which should be announced
 *
 * This function sends an announcement. It is called from multiple
 * places.
 */
static void bla_send_announce(struct bat_priv *bat_priv,
			      struct backbone_gw *backbone_gw)
{
	uint8_t mac[ETH_ALEN];
	uint16_t crc;

	memcpy(mac, announce_mac, 4);
	crc = htons(backbone_gw->crc);
	memcpy(&mac[4], (uint8_t *)&crc, 2);

	bla_send_claim(bat_priv, mac, backbone_gw->vid, CLAIM_TYPE_ANNOUNCE);

}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @mac: the mac address of the claim
 * @vid: the VLAN ID of the frame
 * @backbone_gw: the backbone gateway which claims it
 *
 * Adds a claim in the claim hash.
 */
static void bla_add_claim(struct bat_priv *bat_priv, const uint8_t *mac,
			  const short vid, struct backbone_gw *backbone_gw)
{
	struct claim *claim;
	struct claim search_claim;
	int hash_added;

	memcpy(search_claim.addr, mac, ETH_ALEN);
	search_claim.vid = vid;
	claim = claim_hash_find(bat_priv, &search_claim);

	/* create a new claim entry if it does not exist yet. */
	if (!claim) {
		claim = kzalloc(sizeof(*claim), GFP_ATOMIC);
		if (!claim)
			return;

		memcpy(claim->addr, mac, ETH_ALEN);
		claim->vid = vid;
		claim->lasttime = jiffies;
		claim->backbone_gw = backbone_gw;

		atomic_set(&claim->refcount, 2);
		bat_dbg(DBG_BLA, bat_priv,
			"bla_add_claim(): adding new entry %pM, vid %d to hash ...\n",
			mac, vid);
		hash_added = hash_add(bat_priv->claim_hash, compare_claim,
				      choose_claim, claim, &claim->hash_entry);

		if (unlikely(hash_added != 0)) {
			/* only local changes happened. */
			kfree(claim);
			return;
		}
	} else {
		claim->lasttime = jiffies;
		if (claim->backbone_gw == backbone_gw)
			/* no need to register a new backbone */
			goto claim_free_ref;

		bat_dbg(DBG_BLA, bat_priv,
			"bla_add_claim(): changing ownership for %pM, vid %d\n",
			mac, vid);

		claim->backbone_gw->crc ^=
			crc16(0, claim->addr, ETH_ALEN);
		backbone_gw_free_ref(claim->backbone_gw);

	}
	/* set (new) backbone gw */
	atomic_inc(&backbone_gw->refcount);
	claim->backbone_gw = backbone_gw;

	backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
	backbone_gw->lasttime = jiffies;

claim_free_ref:
	claim_free_ref(claim);
}

/* Delete a claim from the claim hash which has the
 * given mac address and vid.
 */
static void bla_del_claim(struct bat_priv *bat_priv, const uint8_t *mac,
			  const short vid)
{
	struct claim search_claim, *claim;

	memcpy(search_claim.addr, mac, ETH_ALEN);
	search_claim.vid = vid;
	claim = claim_hash_find(bat_priv, &search_claim);
	if (!claim)
		return;

	bat_dbg(DBG_BLA, bat_priv, "bla_del_claim(): %pM, vid %d\n", mac, vid);

	hash_remove(bat_priv->claim_hash, compare_claim, choose_claim, claim);
	claim_free_ref(claim); /* reference from the hash is gone */

	claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);

	/* don't need the reference from hash_find() anymore */
	claim_free_ref(claim);
}

/* check for ANNOUNCE frame, return 1 if handled */
static int handle_announce(struct bat_priv *bat_priv,
			   uint8_t *an_addr, uint8_t *backbone_addr, short vid)
{
	struct backbone_gw *backbone_gw;
	uint16_t crc;

	if (memcmp(an_addr, announce_mac, 4) != 0)
		return 0;

	backbone_gw = bla_get_backbone_gw(bat_priv, backbone_addr, vid);

	if (unlikely(!backbone_gw))
		return 1;


	/* handle as ANNOUNCE frame */
	backbone_gw->lasttime = jiffies;
	crc = ntohs(*((uint16_t *)(&an_addr[4])));

	bat_dbg(DBG_BLA, bat_priv,
		"handle_announce(): ANNOUNCE vid %d (sent by %pM)... CRC = %04x\n",
		vid, backbone_gw->orig, crc);

	if (backbone_gw->crc != crc) {
		bat_dbg(DBG_BLA, backbone_gw->bat_priv,
			"handle_announce(): CRC FAILED for %pM/%d (my = %04x, sent = %04x)\n",
			backbone_gw->orig, backbone_gw->vid, backbone_gw->crc,
			crc);

		bla_send_request(backbone_gw);
	} else {
		/* if we have sent a request and the crc was OK,
		 * we can allow traffic again.
		 */
		if (atomic_read(&backbone_gw->request_sent)) {
			atomic_dec(&backbone_gw->bat_priv->bla_num_requests);
			atomic_set(&backbone_gw->request_sent, 0);
		}
	}

	backbone_gw_free_ref(backbone_gw);
	return 1;
}

/* check for REQUEST frame, return 1 if handled */
static int handle_request(struct bat_priv *bat_priv,
			  struct hard_iface *primary_if,
			  uint8_t *backbone_addr,
			  struct ethhdr *ethhdr, short vid)
{
	/* check for REQUEST frame */
	if (!compare_eth(backbone_addr, ethhdr->h_dest))
		return 0;

	/* sanity check, this should not happen on a normal switch,
	 * we ignore it in this case.
	 */
	if (!compare_eth(ethhdr->h_dest, primary_if->net_dev->dev_addr))
		return 1;

	bat_dbg(DBG_BLA, bat_priv,
		"handle_request(): REQUEST vid %d (sent by %pM)...\n",
		vid, ethhdr->h_source);

	bla_answer_request(bat_priv, primary_if, vid);
	return 1;
}

/* check for UNCLAIM frame, return 1 if handled */
static int handle_unclaim(struct bat_priv *bat_priv,
			  struct hard_iface *primary_if,
			  uint8_t *backbone_addr,
			  uint8_t *claim_addr, short vid)
{
	struct backbone_gw *backbone_gw;

	/* unclaim in any case if it is our own */
	if (primary_if && compare_eth(backbone_addr,
				      primary_if->net_dev->dev_addr))
		bla_send_claim(bat_priv, claim_addr, vid, CLAIM_TYPE_DEL);

	backbone_gw = backbone_hash_find(bat_priv, backbone_addr, vid);

	if (!backbone_gw)
		return 1;

	/* this must be an UNCLAIM frame */
	bat_dbg(DBG_BLA, bat_priv,
		"handle_unclaim(): UNCLAIM %pM on vid %d (sent by %pM)...\n",
		claim_addr, vid, backbone_gw->orig);

	bla_del_claim(bat_priv, claim_addr, vid);
	backbone_gw_free_ref(backbone_gw);
	return 1;
}

/* check for CLAIM frame, return 1 if handled */
static int handle_claim(struct bat_priv *bat_priv,
			struct hard_iface *primary_if, uint8_t *backbone_addr,
			uint8_t *claim_addr, short vid)
{
	struct backbone_gw *backbone_gw;

	/* register the gateway if not yet available, and add the claim. */

	backbone_gw = bla_get_backbone_gw(bat_priv, backbone_addr, vid);

	if (unlikely(!backbone_gw))
		return 1;

	/* this must be a CLAIM frame */
	bla_add_claim(bat_priv, claim_addr, vid, backbone_gw);
	if (compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
		bla_send_claim(bat_priv, claim_addr, vid, CLAIM_TYPE_ADD);

	/* TODO: we could call something like tt_local_del() here. */

	backbone_gw_free_ref(backbone_gw);
	return 1;
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 *
 * Check if this is a claim frame, and process it accordingly.
 *
 * returns 1 if it was a claim frame, otherwise return 0 to
 * tell the callee that it can use the frame on its own.
 */
static int bla_process_claim(struct bat_priv *bat_priv,
			     struct hard_iface *primary_if,
			     struct sk_buff *skb)
{
	struct ethhdr *ethhdr;
	struct vlan_ethhdr *vhdr;
	struct arphdr *arphdr;
	uint8_t *hw_src, *hw_dst;
	struct bla_claim_dst *bla_dst;
	uint16_t proto;
	int headlen;
	short vid = -1;

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

	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
		vhdr = (struct vlan_ethhdr *)ethhdr;
		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
		proto = ntohs(vhdr->h_vlan_encapsulated_proto);
		headlen = sizeof(*vhdr);
	} else {
		proto = ntohs(ethhdr->h_proto);
		headlen = sizeof(*ethhdr);
	}

	if (proto != ETH_P_ARP)
		return 0; /* not a claim frame */

	/* this must be a ARP frame. check if it is a claim. */

	if (unlikely(!pskb_may_pull(skb, headlen + arp_hdr_len(skb->dev))))
		return 0;

	/* pskb_may_pull() may have modified the pointers, get ethhdr again */
	ethhdr = (struct ethhdr *)skb_mac_header(skb);
	arphdr = (struct arphdr *)((uint8_t *)ethhdr + headlen);

	/* Check whether the ARP frame carries a valid
	 * IP information
	 */

	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
		return 0;
	if (arphdr->ar_pro != htons(ETH_P_IP))
		return 0;
	if (arphdr->ar_hln != ETH_ALEN)
		return 0;
	if (arphdr->ar_pln != 4)
		return 0;

	hw_src = (uint8_t *)arphdr + sizeof(struct arphdr);
	hw_dst = hw_src + ETH_ALEN + 4;
	bla_dst = (struct bla_claim_dst *)hw_dst;

	/* check if it is a claim frame. */
	if (memcmp(hw_dst, claim_dest, 3) != 0)
		return 0;

	/* become a backbone gw ourselves on this vlan if not happened yet */
	bla_update_own_backbone_gw(bat_priv, primary_if, vid);

	/* check for the different types of claim frames ... */
	switch (bla_dst->type) {
	case CLAIM_TYPE_ADD:
		if (handle_claim(bat_priv, primary_if, hw_src,
				 ethhdr->h_source, vid))
			return 1;
		break;
	case CLAIM_TYPE_DEL:
		if (handle_unclaim(bat_priv, primary_if,
				   ethhdr->h_source, hw_src, vid))
			return 1;
		break;

	case CLAIM_TYPE_ANNOUNCE:
		if (handle_announce(bat_priv, hw_src, ethhdr->h_source, vid))
			return 1;
		break;
	case CLAIM_TYPE_REQUEST:
		if (handle_request(bat_priv, primary_if, hw_src, ethhdr, vid))
			return 1;
		break;
	}

	bat_dbg(DBG_BLA, bat_priv,
		"bla_process_claim(): ERROR - this looks like a claim frame, but is useless. eth src %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
		ethhdr->h_source, vid, hw_src, hw_dst);
	return 1;
}

/* Check when we last heard from other nodes, and remove them in case of
 * a time out, or clean all backbone gws if now is set.
 */
static void bla_purge_backbone_gw(struct bat_priv *bat_priv, int now)
{
	struct backbone_gw *backbone_gw;
	struct hlist_node *node, *node_tmp;
	struct hlist_head *head;
	struct hashtable_t *hash;
	spinlock_t *list_lock;	/* protects write access to the hash lists */
	int i;

	hash = bat_priv->backbone_hash;
	if (!hash)
		return;

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

		spin_lock_bh(list_lock);
		hlist_for_each_entry_safe(backbone_gw, node, node_tmp,
					  head, hash_entry) {
			if (now)
				goto purge_now;
			if (!has_timed_out(backbone_gw->lasttime,
					   BLA_BACKBONE_TIMEOUT))
				continue;

			bat_dbg(DBG_BLA, backbone_gw->bat_priv,
				"bla_purge_backbone_gw(): backbone gw %pM timed out\n",
				backbone_gw->orig);

purge_now:
			/* don't wait for the pending request anymore */
			if (atomic_read(&backbone_gw->request_sent))
				atomic_dec(&bat_priv->bla_num_requests);

			bla_del_backbone_claims(backbone_gw);

			hlist_del_rcu(node);
			backbone_gw_free_ref(backbone_gw);
		}
		spin_unlock_bh(list_lock);
	}
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the selected primary interface, may be NULL if now is set
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we heard last time from our own claims, and remove them in case of
 * a time out, or clean all claims if now is set
 */
static void bla_purge_claims(struct bat_priv *bat_priv,
			     struct hard_iface *primary_if, int now)
{
	struct claim *claim;
	struct hlist_node *node;
	struct hlist_head *head;
	struct hashtable_t *hash;
	int i;

	hash = bat_priv->claim_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
			if (now)
				goto purge_now;
			if (!compare_eth(claim->backbone_gw->orig,
					 primary_if->net_dev->dev_addr))
				continue;
			if (!has_timed_out(claim->lasttime,
					   BLA_CLAIM_TIMEOUT))
				continue;

			bat_dbg(DBG_BLA, bat_priv,
				"bla_purge_claims(): %pM, vid %d, time out\n",
				claim->addr, claim->vid);

purge_now:
			handle_unclaim(bat_priv, primary_if,
				       claim->backbone_gw->orig,
				       claim->addr, claim->vid);
		}
		rcu_read_unlock();
	}
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the new selected primary_if
 * @oldif: the old primary interface, may be NULL
 *
 * Update the backbone gateways when the own orig address changes.
 *
 */
void bla_update_orig_address(struct bat_priv *bat_priv,
			     struct hard_iface *primary_if,
			     struct hard_iface *oldif)
{
	struct backbone_gw *backbone_gw;
	struct hlist_node *node;
	struct hlist_head *head;
	struct hashtable_t *hash;
	int i;

	if (!oldif) {
		bla_purge_claims(bat_priv, NULL, 1);
		bla_purge_backbone_gw(bat_priv, 1);
		return;
	}

	hash = bat_priv->backbone_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
			/* own orig still holds the old value. */
			if (!compare_eth(backbone_gw->orig,
					 oldif->net_dev->dev_addr))
				continue;

			memcpy(backbone_gw->orig,
			       primary_if->net_dev->dev_addr, ETH_ALEN);
			/* send an announce frame so others will ask for our
			 * claims and update their tables.
			 */
			bla_send_announce(bat_priv, backbone_gw);
		}
		rcu_read_unlock();
	}
}



/* (re)start the timer */
static void bla_start_timer(struct bat_priv *bat_priv)
{
	INIT_DELAYED_WORK(&bat_priv->bla_work, bla_periodic_work);
	queue_delayed_work(bat_event_workqueue, &bat_priv->bla_work,
			   msecs_to_jiffies(BLA_PERIOD_LENGTH));
}

/* periodic work to do:
 *  * purge structures when they are too old
 *  * send announcements
 */
static void bla_periodic_work(struct work_struct *work)
{
	struct delayed_work *delayed_work =
		container_of(work, struct delayed_work, work);
	struct bat_priv *bat_priv =
		container_of(delayed_work, struct bat_priv, bla_work);
	struct hlist_node *node;
	struct hlist_head *head;
	struct backbone_gw *backbone_gw;
	struct hashtable_t *hash;
	struct hard_iface *primary_if;
	int i;

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

	bla_purge_claims(bat_priv, primary_if, 0);
	bla_purge_backbone_gw(bat_priv, 0);

	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
		goto out;

	hash = bat_priv->backbone_hash;
	if (!hash)
		goto out;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
			if (!compare_eth(backbone_gw->orig,
					 primary_if->net_dev->dev_addr))
				continue;

			backbone_gw->lasttime = jiffies;

			bla_send_announce(bat_priv, backbone_gw);
		}
		rcu_read_unlock();
	}
out:
	if (primary_if)
		hardif_free_ref(primary_if);

	bla_start_timer(bat_priv);
}

/* initialize all bla structures */
int bla_init(struct bat_priv *bat_priv)
{
	int i;

	bat_dbg(DBG_BLA, bat_priv, "bla hash registering\n");

	/* initialize the duplicate list */
	for (i = 0; i < DUPLIST_SIZE; i++)
		bat_priv->bcast_duplist[i].entrytime =
			jiffies - msecs_to_jiffies(DUPLIST_TIMEOUT);
	bat_priv->bcast_duplist_curr = 0;

	if (bat_priv->claim_hash)
		return 1;

	bat_priv->claim_hash = hash_new(128);
	bat_priv->backbone_hash = hash_new(32);

	if (!bat_priv->claim_hash || !bat_priv->backbone_hash)
		return -1;

	bat_dbg(DBG_BLA, bat_priv, "bla hashes initialized\n");

	bla_start_timer(bat_priv);
	return 1;
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @bcast_packet: originator mac address
 * @hdr_size: maximum length of the frame
 *
 * check if it is on our broadcast list. Another gateway might
 * have sent the same packet because it is connected to the same backbone,
 * so we have to remove this duplicate.
 *
 * This is performed by checking the CRC, which will tell us
 * with a good chance that it is the same packet. If it is furthermore
 * sent by another host, drop it. We allow equal packets from
 * the same host however as this might be intended.
 *
 **/

int bla_check_bcast_duplist(struct bat_priv *bat_priv,
			    struct bcast_packet *bcast_packet,
			    int hdr_size)
{
	int i, length, curr;
	uint8_t *content;
	uint16_t crc;
	struct bcast_duplist_entry *entry;

	length = hdr_size - sizeof(*bcast_packet);
	content = (uint8_t *)bcast_packet;
	content += sizeof(*bcast_packet);

	/* calculate the crc ... */
	crc = crc16(0, content, length);

	for (i = 0 ; i < DUPLIST_SIZE; i++) {
		curr = (bat_priv->bcast_duplist_curr + i) % DUPLIST_SIZE;
		entry = &bat_priv->bcast_duplist[curr];

		/* we can stop searching if the entry is too old ;
		 * later entries will be even older
		 */
		if (has_timed_out(entry->entrytime, DUPLIST_TIMEOUT))
			break;

		if (entry->crc != crc)
			continue;

		if (compare_eth(entry->orig, bcast_packet->orig))
			continue;

		/* this entry seems to match: same crc, not too old,
		 * and from another gw. therefore return 1 to forbid it.
		 */
		return 1;
	}
	/* not found, add a new entry (overwrite the oldest entry) */
	curr = (bat_priv->bcast_duplist_curr + DUPLIST_SIZE - 1) % DUPLIST_SIZE;
	entry = &bat_priv->bcast_duplist[curr];
	entry->crc = crc;
	entry->entrytime = jiffies;
	memcpy(entry->orig, bcast_packet->orig, ETH_ALEN);
	bat_priv->bcast_duplist_curr = curr;

	/* allow it, its the first occurence. */
	return 0;
}



/**
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: originator mac address
 *
 * check if the originator is a gateway for any VLAN ID.
 *
 * returns 1 if it is found, 0 otherwise
 *
 */

int bla_is_backbone_gw_orig(struct bat_priv *bat_priv, uint8_t *orig)
{
	struct hashtable_t *hash = bat_priv->backbone_hash;
	struct hlist_head *head;
	struct hlist_node *node;
	struct backbone_gw *backbone_gw;
	int i;

	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
		return 0;

	if (!hash)
		return 0;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
			if (compare_eth(backbone_gw->orig, orig)) {
				rcu_read_unlock();
				return 1;
			}
		}
		rcu_read_unlock();
	}

	return 0;
}


/**
 * @skb: the frame to be checked
 * @orig_node: the orig_node of the frame
 * @hdr_size: maximum length of the frame
 *
 * bla_is_backbone_gw inspects the skb for the VLAN ID and returns 1
 * if the orig_node is also a gateway on the soft interface, otherwise it
 * returns 0.
 *
 */
int bla_is_backbone_gw(struct sk_buff *skb,
		       struct orig_node *orig_node, int hdr_size)
{
	struct ethhdr *ethhdr;
	struct vlan_ethhdr *vhdr;
	struct backbone_gw *backbone_gw;
	short vid = -1;

	if (!atomic_read(&orig_node->bat_priv->bridge_loop_avoidance))
		return 0;

	/* first, find out the vid. */
	if (!pskb_may_pull(skb, hdr_size + sizeof(struct ethhdr)))
		return 0;

	ethhdr = (struct ethhdr *)(((uint8_t *)skb->data) + hdr_size);

	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
		if (!pskb_may_pull(skb, hdr_size + sizeof(struct vlan_ethhdr)))
			return 0;

		vhdr = (struct vlan_ethhdr *)(((uint8_t *)skb->data) +
					      hdr_size);
		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
	}

	/* see if this originator is a backbone gw for this VLAN */

	backbone_gw = backbone_hash_find(orig_node->bat_priv,
					 orig_node->orig, vid);
	if (!backbone_gw)
		return 0;

	backbone_gw_free_ref(backbone_gw);
	return 1;
}

/* free all bla structures (for softinterface free or module unload) */
void bla_free(struct bat_priv *bat_priv)
{
	struct hard_iface *primary_if;

	cancel_delayed_work_sync(&bat_priv->bla_work);
	primary_if = primary_if_get_selected(bat_priv);

	if (bat_priv->claim_hash) {
		bla_purge_claims(bat_priv, primary_if, 1);
		hash_destroy(bat_priv->claim_hash);
		bat_priv->claim_hash = NULL;
	}
	if (bat_priv->backbone_hash) {
		bla_purge_backbone_gw(bat_priv, 1);
		hash_destroy(bat_priv->backbone_hash);
		bat_priv->backbone_hash = NULL;
	}
	if (primary_if)
		hardif_free_ref(primary_if);
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 *
 * bla_rx avoidance checks if:
 *  * we have to race for a claim
 *  * if the frame is allowed on the LAN
 *
 * in these cases, the skb is further handled by this function and
 * returns 1, otherwise it returns 0 and the caller shall further
 * process the skb.
 *
 */
int bla_rx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid)
{
	struct ethhdr *ethhdr;
	struct claim search_claim, *claim = NULL;
	struct hard_iface *primary_if;
	int ret;

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

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

	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
		goto allow;


	if (unlikely(atomic_read(&bat_priv->bla_num_requests)))
		/* don't allow broadcasts while requests are in flight */
		if (is_multicast_ether_addr(ethhdr->h_dest))
			goto handled;

	memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
	search_claim.vid = vid;
	claim = claim_hash_find(bat_priv, &search_claim);

	if (!claim) {
		/* possible optimization: race for a claim */
		/* No claim exists yet, claim it for us!
		 */
		handle_claim(bat_priv, primary_if,
			     primary_if->net_dev->dev_addr,
			     ethhdr->h_source, vid);
		goto allow;
	}

	/* if it is our own claim ... */
	if (compare_eth(claim->backbone_gw->orig,
			primary_if->net_dev->dev_addr)) {
		/* ... allow it in any case */
		claim->lasttime = jiffies;
		goto allow;
	}

	/* if it is a broadcast ... */
	if (is_multicast_ether_addr(ethhdr->h_dest)) {
		/* ... drop it. the responsible gateway is in charge. */
		goto handled;
	} else {
		/* seems the client considers us as its best gateway.
		 * send a claim and update the claim table
		 * immediately.
		 */
		handle_claim(bat_priv, primary_if,
			     primary_if->net_dev->dev_addr,
			     ethhdr->h_source, vid);
		goto allow;
	}
allow:
	bla_update_own_backbone_gw(bat_priv, primary_if, vid);
	ret = 0;
	goto out;

handled:
	kfree_skb(skb);
	ret = 1;

out:
	if (primary_if)
		hardif_free_ref(primary_if);
	if (claim)
		claim_free_ref(claim);
	return ret;
}

/**
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 *
 * bla_tx checks if:
 *  * a claim was received which has to be processed
 *  * the frame is allowed on the mesh
 *
 * in these cases, the skb is further handled by this function and
 * returns 1, otherwise it returns 0 and the caller shall further
 * process the skb.
 *
 */
int bla_tx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid)
{
	struct ethhdr *ethhdr;
	struct claim search_claim, *claim = NULL;
	struct hard_iface *primary_if;
	int ret = 0;

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

	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
		goto allow;

	/* in VLAN case, the mac header might not be set. */
	skb_reset_mac_header(skb);

	if (bla_process_claim(bat_priv, primary_if, skb))
		goto handled;

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

	if (unlikely(atomic_read(&bat_priv->bla_num_requests)))
		/* don't allow broadcasts while requests are in flight */
		if (is_multicast_ether_addr(ethhdr->h_dest))
			goto handled;

	memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
	search_claim.vid = vid;

	claim = claim_hash_find(bat_priv, &search_claim);

	/* if no claim exists, allow it. */
	if (!claim)
		goto allow;

	/* check if we are responsible. */
	if (compare_eth(claim->backbone_gw->orig,
			primary_if->net_dev->dev_addr)) {
		/* if yes, the client has roamed and we have
		 * to unclaim it.
		 */
		handle_unclaim(bat_priv, primary_if,
			       primary_if->net_dev->dev_addr,
			       ethhdr->h_source, vid);
		goto allow;
	}

	/* check if it is a multicast/broadcast frame */
	if (is_multicast_ether_addr(ethhdr->h_dest)) {
		/* drop it. the responsible gateway has forwarded it into
		 * the backbone network.
		 */
		goto handled;
	} else {
		/* we must allow it. at least if we are
		 * responsible for the DESTINATION.
		 */
		goto allow;
	}
allow:
	bla_update_own_backbone_gw(bat_priv, primary_if, vid);
	ret = 0;
	goto out;
handled:
	ret = 1;
out:
	if (primary_if)
		hardif_free_ref(primary_if);
	if (claim)
		claim_free_ref(claim);
	return ret;
}

int bla_claim_table_seq_print_text(struct seq_file *seq, void *offset)
{
	struct net_device *net_dev = (struct net_device *)seq->private;
	struct bat_priv *bat_priv = netdev_priv(net_dev);
	struct hashtable_t *hash = bat_priv->claim_hash;
	struct claim *claim;
	struct hard_iface *primary_if;
	struct hlist_node *node;
	struct hlist_head *head;
	uint32_t i;
	bool is_own;
	int ret = 0;

	primary_if = primary_if_get_selected(bat_priv);
	if (!primary_if) {
		ret = seq_printf(seq,
				 "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
				 net_dev->name);
		goto out;
	}

	if (primary_if->if_status != IF_ACTIVE) {
		ret = seq_printf(seq,
				 "BATMAN mesh %s disabled - primary interface not active\n",
				 net_dev->name);
		goto out;
	}

	seq_printf(seq, "Claims announced for the mesh %s (orig %pM)\n",
		   net_dev->name, primary_if->net_dev->dev_addr);
	seq_printf(seq, "   %-17s    %-5s    %-17s [o] (%-4s)\n",
		   "Client", "VID", "Originator", "CRC");
	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
			is_own = compare_eth(claim->backbone_gw->orig,
					     primary_if->net_dev->dev_addr);
			seq_printf(seq,	" * %pM on % 5d by %pM [%c] (%04x)\n",
				   claim->addr, claim->vid,
				   claim->backbone_gw->orig,
				   (is_own ? 'x' : ' '),
				   claim->backbone_gw->crc);
		}
		rcu_read_unlock();
	}
out:
	if (primary_if)
		hardif_free_ref(primary_if);
	return ret;
}