提交 c384ea3e 编写于 作者: A Antonio Quartulli

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: NAntonio Quartulli <ordex@autistici.org>
上级 5c3a0e55
......@@ -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;
}
......@@ -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
......
......@@ -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
......
......@@ -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;
......
......@@ -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) {
......
......@@ -20,6 +20,7 @@
#include "main.h"
#include "soft-interface.h"
#include "hard-interface.h"
#include "distributed-arp-table.h"
#include "routing.h"
#include "send.h"
#include "debugfs.h"
......@@ -155,6 +156,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
short vid __maybe_unused = -1;
bool do_bcast = false;
uint32_t seqno;
unsigned long brd_delay = 1;
if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
goto dropped;
......@@ -224,6 +226,13 @@ static int batadv_interface_tx(struct sk_buff *skb,
if (!primary_if)
goto dropped;
/* in case of ARP request, we do not immediately broadcasti the
* packet, instead we first wait for DAT to try to retrieve the
* correct ARP entry
*/
if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
brd_delay = msecs_to_jiffies(ARP_REQ_DELAY);
if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0)
goto dropped;
......@@ -245,7 +254,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
seqno = atomic_inc_return(&bat_priv->bcast_seqno);
bcast_packet->seqno = htonl(seqno);
batadv_add_bcast_packet_to_list(bat_priv, skb, 1);
batadv_add_bcast_packet_to_list(bat_priv, skb, brd_delay);
/* a copy is stored in the bcast list, therefore removing
* the original skb.
......@@ -260,6 +269,11 @@ static int batadv_interface_tx(struct sk_buff *skb,
goto dropped;
}
if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
goto dropped;
batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);
ret = batadv_unicast_send_skb(bat_priv, skb);
if (ret != 0)
goto dropped_freed;
......
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