Commit c384ea3e authored by Antonio Quartulli's avatar Antonio Quartulli
Browse files

batman-adv: Distributed ARP Table - add snooping functions for ARP messages 



In case of an ARP message going in or out the soft_iface, it is intercepted and
a special action is performed. In particular the DHT helper functions previously
implemented are used to store all the ARP entries belonging to the network in
order to provide a fast and unicast lookup instead of the classic broadcast
flooding mechanism.
Each node stores the entries it is responsible for (following the DHT rules) in
its soft_iface ARP table. This makes it possible to reuse the kernel data
structures and functions for ARP management.

Signed-off-by: default avatarAntonio Quartulli <ordex@autistici.org>
parent 5c3a0e55

net/batman-adv/distributed-arp-table.c

+265 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 


#include <linux/if_ether.h>

#include <linux/if_arp.h>

#include <net/arp.h>



#include "main.h"

#include "hash.h"
@@ -27,6 +28,7 @@ 
#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);
@@ -766,3 +768,266 @@ static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv, 
out:

	return type;

}



/**

 * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to

 * answer using DAT

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: packet to check

 *

 * Returns true if the message has been sent to the dht candidates, false

 * otherwise. In case of true the message has to be enqueued to permit the

 * fallback

 */

bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,

					   struct sk_buff *skb)

{

	uint16_t type = 0;

	__be32 ip_dst, ip_src;

	uint8_t *hw_src;

	bool ret = false;

	struct batadv_dat_entry *dat_entry = NULL;

	struct sk_buff *skb_new;

	struct batadv_hard_iface *primary_if = NULL;



	type = batadv_arp_get_type(bat_priv, skb, 0);

	/* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast

	 * message to the selected DHT candidates

	 */

	if (type != ARPOP_REQUEST)

		goto out;



	batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REQUEST");



	ip_src = batadv_arp_ip_src(skb, 0);

	hw_src = batadv_arp_hw_src(skb, 0);

	ip_dst = batadv_arp_ip_dst(skb, 0);



	batadv_dat_entry_add(bat_priv, ip_src, hw_src);



	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);

	if (dat_entry) {

		primary_if = batadv_primary_if_get_selected(bat_priv);

		if (!primary_if)

			goto out;



		skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,

				     primary_if->soft_iface, ip_dst, hw_src,

				     dat_entry->mac_addr, hw_src);

		if (!skb_new)

			goto out;



		skb_reset_mac_header(skb_new);

		skb_new->protocol = eth_type_trans(skb_new,

						   primary_if->soft_iface);

		bat_priv->stats.rx_packets++;

		bat_priv->stats.rx_bytes += skb->len + ETH_HLEN;

		primary_if->soft_iface->last_rx = jiffies;



		netif_rx(skb_new);

		batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");

		ret = true;

	} else {

		/* Send the request on the DHT */

		ret = batadv_dat_send_data(bat_priv, skb, ip_dst,

					   BATADV_P_DAT_DHT_GET);

	}

out:

	if (dat_entry)

		batadv_dat_entry_free_ref(dat_entry);

	if (primary_if)

		batadv_hardif_free_ref(primary_if);

	return ret;

}



/**

 * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to

 * answer using the local DAT storage

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: packet to check

 * @hdr_size: size of the encapsulation header

 *

 * Returns true if the request has been answered, false otherwise

 */

bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,

					   struct sk_buff *skb, int hdr_size)

{

	uint16_t type;

	__be32 ip_src, ip_dst;

	uint8_t *hw_src;

	struct sk_buff *skb_new;

	struct batadv_hard_iface *primary_if = NULL;

	struct batadv_dat_entry *dat_entry = NULL;

	bool ret = false;

	int err;



	type = batadv_arp_get_type(bat_priv, skb, hdr_size);

	if (type != ARPOP_REQUEST)

		goto out;



	hw_src = batadv_arp_hw_src(skb, hdr_size);

	ip_src = batadv_arp_ip_src(skb, hdr_size);

	ip_dst = batadv_arp_ip_dst(skb, hdr_size);



	batadv_dbg_arp(bat_priv, skb, type, hdr_size,

		       "Parsing incoming ARP REQUEST");



	batadv_dat_entry_add(bat_priv, ip_src, hw_src);



	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);

	if (!dat_entry)

		goto out;



	primary_if = batadv_primary_if_get_selected(bat_priv);

	if (!primary_if)

		goto out;



	skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,

			     primary_if->soft_iface, ip_dst, hw_src,

			     dat_entry->mac_addr, hw_src);



	if (!skb_new)

		goto out;



	/* to preserve backwards compatibility, here the node has to answer

	 * using the same packet type it received for the request. This is due

	 * to that if a node is not using the 4addr packet format it may not

	 * support it.

	 */

	if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))

		err = batadv_unicast_4addr_send_skb(bat_priv, skb_new,

						    BATADV_P_DAT_CACHE_REPLY);

	else

		err = batadv_unicast_send_skb(bat_priv, skb_new);



	if (!err)

		ret = true;

out:

	if (dat_entry)

		batadv_dat_entry_free_ref(dat_entry);

	if (primary_if)

		batadv_hardif_free_ref(primary_if);

	if (ret)

		kfree_skb(skb);

	return ret;

}



/**

 * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: packet to check

 */

void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,

					 struct sk_buff *skb)

{

	uint16_t type;

	__be32 ip_src, ip_dst;

	uint8_t *hw_src, *hw_dst;



	type = batadv_arp_get_type(bat_priv, skb, 0);

	if (type != ARPOP_REPLY)

		return;



	batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REPLY");



	hw_src = batadv_arp_hw_src(skb, 0);

	ip_src = batadv_arp_ip_src(skb, 0);

	hw_dst = batadv_arp_hw_dst(skb, 0);

	ip_dst = batadv_arp_ip_dst(skb, 0);



	batadv_dat_entry_add(bat_priv, ip_src, hw_src);

	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);



	/* Send the ARP reply to the candidates for both the IP addresses that

	 * the node got within the ARP reply

	 */

	batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);

	batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);

}

/**

 * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local

 * DAT storage only

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: packet to check

 * @hdr_size: siaze of the encapsulation header

 */

bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,

					 struct sk_buff *skb, int hdr_size)

{

	uint16_t type;

	__be32 ip_src, ip_dst;

	uint8_t *hw_src, *hw_dst;

	bool ret = false;



	type = batadv_arp_get_type(bat_priv, skb, hdr_size);

	if (type != ARPOP_REPLY)

		goto out;



	batadv_dbg_arp(bat_priv, skb, type, hdr_size,

		       "Parsing incoming ARP REPLY");



	hw_src = batadv_arp_hw_src(skb, hdr_size);

	ip_src = batadv_arp_ip_src(skb, hdr_size);

	hw_dst = batadv_arp_hw_dst(skb, hdr_size);

	ip_dst = batadv_arp_ip_dst(skb, hdr_size);



	/* Update our internal cache with both the IP addresses the node got

	 * within the ARP reply

	 */

	batadv_dat_entry_add(bat_priv, ip_src, hw_src);

	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);



	/* if this REPLY is directed to a client of mine, let's deliver the

	 * packet to the interface

	 */

	ret = !batadv_is_my_client(bat_priv, hw_dst);

out:

	/* if ret == false -> packet has to be delivered to the interface */

	return ret;

}



/**

 * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped

 * (because the node has already got the reply via DAT) or not

 * @bat_priv: the bat priv with all the soft interface information

 * @forw_packet: the broadcast packet

 *

 * Returns true if the node can drop the packet, false otherwise

 */

bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,

				      struct batadv_forw_packet *forw_packet)

{

	uint16_t type;

	__be32 ip_dst;

	struct batadv_dat_entry *dat_entry = NULL;

	bool ret = false;

	const size_t bcast_len = sizeof(struct batadv_bcast_packet);



	/* If this packet is an ARP_REQUEST and the node already has the

	 * information that it is going to ask, then the packet can be dropped

	 */

	if (forw_packet->num_packets)

		goto out;



	type = batadv_arp_get_type(bat_priv, forw_packet->skb, bcast_len);

	if (type != ARPOP_REQUEST)

		goto out;



	ip_dst = batadv_arp_ip_dst(forw_packet->skb, bcast_len);

	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);

	/* check if the node already got this entry */

	if (!dat_entry) {

		batadv_dbg(BATADV_DBG_DAT, bat_priv,

			   "ARP Request for %pI4: fallback\n", &ip_dst);

		goto out;

	}



	batadv_dbg(BATADV_DBG_DAT, bat_priv,

		   "ARP Request for %pI4: fallback prevented\n", &ip_dst);

	ret = true;



out:

	if (dat_entry)

		batadv_dat_entry_free_ref(dat_entry);

	return ret;

}

net/batman-adv/distributed-arp-table.h

+11 −0
Original line number Diff line number Diff line
@@ -27,6 +27,17 @@ 


#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)



bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,

					   struct sk_buff *skb);

bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,

					   struct sk_buff *skb, int hdr_size);

void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,

					 struct sk_buff *skb);

bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,

					 struct sk_buff *skb, int hdr_size);

bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,

				      struct batadv_forw_packet *forw_packet);



/**

 * batadv_dat_init_orig_node_addr - assign a DAT address to the orig_node

 * @orig_node: the node to assign the DAT address to

net/batman-adv/main.h

+2 −0
Original line number Diff line number Diff line
@@ -74,6 +74,8 @@ 


#define BATADV_LOG_BUF_LEN 8192	  /* has to be a power of 2 */



/* msecs after which an ARP_REQUEST is sent in broadcast as fallback */

#define ARP_REQ_DELAY 250

/* numbers of originator to contact for any PUT/GET DHT operation */

#define BATADV_DAT_CANDIDATES_NUM 3

net/batman-adv/routing.c

+28 −1
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include "vis.h"

#include "unicast.h"

#include "bridge_loop_avoidance.h"

#include "distributed-arp-table.h"



static int batadv_route_unicast_packet(struct sk_buff *skb,

				       struct batadv_hard_iface *recv_if);
@@ -985,11 +986,13 @@ int batadv_recv_unicast_packet(struct sk_buff *skb, 
	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);

	struct batadv_unicast_packet *unicast_packet;

	int hdr_size = sizeof(*unicast_packet);

	bool is4addr;



	unicast_packet = (struct batadv_unicast_packet *)skb->data;



	is4addr = unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR;

	/* the caller function should have already pulled 2 bytes */

	if (unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR)

	if (is4addr)

		hdr_size = sizeof(struct batadv_unicast_4addr_packet);



	if (batadv_check_unicast_packet(skb, hdr_size) < 0)
@@ -1000,9 +1003,17 @@ int batadv_recv_unicast_packet(struct sk_buff *skb, 


	/* packet for me */

	if (batadv_is_my_mac(unicast_packet->dest)) {

		if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb,

							  hdr_size))

			goto rx_success;

		if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb,

							hdr_size))

			goto rx_success;



		batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size,

				    NULL);



rx_success:

		return NET_RX_SUCCESS;

	}
@@ -1038,8 +1049,17 @@ int batadv_recv_ucast_frag_packet(struct sk_buff *skb, 
		if (!new_skb)

			return NET_RX_SUCCESS;



		if (batadv_dat_snoop_incoming_arp_request(bat_priv, new_skb,

							  hdr_size))

			goto rx_success;

		if (batadv_dat_snoop_incoming_arp_reply(bat_priv, new_skb,

							hdr_size))

			goto rx_success;



		batadv_interface_rx(recv_if->soft_iface, new_skb, recv_if,

				    sizeof(struct batadv_unicast_packet), NULL);



rx_success:

		return NET_RX_SUCCESS;

	}
@@ -1131,9 +1151,16 @@ int batadv_recv_bcast_packet(struct sk_buff *skb, 
	if (batadv_bla_is_backbone_gw(skb, orig_node, hdr_size))

		goto out;



	if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb, hdr_size))

		goto rx_success;

	if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb, hdr_size))

		goto rx_success;



	/* broadcast for me */

	batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size,

			    orig_node);



rx_success:

	ret = NET_RX_SUCCESS;

	goto out;

net/batman-adv/send.c

+4 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
 */



#include "main.h"

#include "distributed-arp-table.h"

#include "send.h"

#include "routing.h"

#include "translation-table.h"
@@ -209,6 +210,9 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work) 
	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) {

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