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batman-adv: Distributed ARP Table - add ARP parsing functions

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ARP messages are now parsed to make it possible to trigger special actions
depending on their types (snooping).

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
This commit is contained in:
Antonio Quartulli 2011-06-02 12:29:51 +02:00
parent 2f1dfbe185
commit 5c3a0e5535
4 changed files with 213 additions and 3 deletions
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4
net/batman-adv/Kconfig
View File

@ -4,7 +4,7 @@
config BATMAN_ADV
tristate "B.A.T.M.A.N. Advanced Meshing Protocol"
depends on NET
depends on NET && INET
select CRC16
default n
help
@ -16,7 +16,7 @@ config BATMAN_ADV
config BATMAN_ADV_BLA
bool "Bridge Loop Avoidance"
depends on BATMAN_ADV && INET
depends on BATMAN_ADV
default y
help
This option enables BLA (Bridge Loop Avoidance), a mechanism

202
net/batman-adv/distributed-arp-table.c
View File

@ -21,6 +21,7 @@
#include <linux/if_arp.h>
#include "main.h"
#include "hash.h"
#include "distributed-arp-table.h"
#include "hard-interface.h"
#include "originator.h"
@ -141,6 +142,59 @@ static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
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 + hdr_size);
addr += ETH_HLEN + sizeof(struct arphdr);
return addr;
}
/**
* batadv_arp_ip_src - extract the ip_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 ip_src field in the ARP packet
*/
static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
{
return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
}
/**
* batadv_arp_hw_dst - extract the hw_dst 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_dst field in the ARP packet
*/
static uint8_t *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
{
return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
}
/**
* batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
*
* Returns the value of the ip_dst field in the ARP packet
*/
static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
{
return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
}
/**
* batadv_hash_dat - compute the hash value for an IP address
* @data: data to hash
@ -257,6 +311,93 @@ out:
batadv_dat_entry_free_ref(dat_entry);
}
#ifdef CONFIG_BATMAN_ADV_DEBUG
/**
* batadv_dbg_arp - print a debug message containing all the ARP packet details
* @bat_priv: the bat priv with all the soft interface information
* @skb: ARP packet
* @type: ARP type
* @hdr_size: size of the possible header before the ARP packet
* @msg: message to print together with the debugging information
*/
static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
uint16_t type, int hdr_size, char *msg)
{
struct batadv_unicast_4addr_packet *unicast_4addr_packet;
struct batadv_bcast_packet *bcast_pkt;
uint8_t *orig_addr;
__be32 ip_src, ip_dst;
if (msg)
batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
ip_src = batadv_arp_ip_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
batadv_arp_hw_src(skb, hdr_size), &ip_src,
batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
if (hdr_size == 0)
return;
/* if the ARP packet is encapsulated in a batman packet, let's print
* some debug messages
*/
unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
switch (unicast_4addr_packet->u.header.packet_type) {
case BATADV_UNICAST:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a UNICAST packet\n");
break;
case BATADV_UNICAST_4ADDR:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
unicast_4addr_packet->src);
switch (unicast_4addr_packet->subtype) {
case BATADV_P_DAT_DHT_PUT:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
break;
case BATADV_P_DAT_DHT_GET:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
break;
case BATADV_P_DAT_CACHE_REPLY:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* type: DAT_CACHE_REPLY\n");
break;
case BATADV_P_DATA:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
break;
default:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
unicast_4addr_packet->u.header.packet_type);
}
break;
case BATADV_BCAST:
bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
orig_addr = bcast_pkt->orig;
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a BCAST packet (src: %pM)\n",
orig_addr);
break;
default:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within an unknown packet type (0x%x)\n",
unicast_4addr_packet->u.header.packet_type);
}
}
#else
static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
uint16_t type, int hdr_size, char *msg)
{
}
#endif /* CONFIG_BATMAN_ADV_DEBUG */
/**
* batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
* @res: the array with the already selected candidates
@ -564,3 +705,64 @@ out:
batadv_hardif_free_ref(primary_if);
return 0;
}
/**
* batadv_arp_get_type - parse an ARP packet and gets the type
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to analyse
* @hdr_size: size of the possible header before the ARP packet in the skb
*
* Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise
*/
static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
struct sk_buff *skb, int hdr_size)
{
struct arphdr *arphdr;
struct ethhdr *ethhdr;
__be32 ip_src, ip_dst;
uint16_t type = 0;
/* pull the ethernet header */
if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
goto out;
ethhdr = (struct ethhdr *)(skb->data + hdr_size);
if (ethhdr->h_proto != htons(ETH_P_ARP))
goto out;
/* pull the ARP payload */
if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
arp_hdr_len(skb->dev))))
goto out;
arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
/* Check whether the ARP packet carries a valid
* IP information
*/
if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
goto out;
if (arphdr->ar_pro != htons(ETH_P_IP))
goto out;
if (arphdr->ar_hln != ETH_ALEN)
goto out;
if (arphdr->ar_pln != 4)
goto out;
/* Check for bad reply/request. If the ARP message is not sane, DAT
* will simply ignore it
*/
ip_src = batadv_arp_ip_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst))
goto out;
type = ntohs(arphdr->ar_op);
out:
return type;
}

2
net/batman-adv/distributed-arp-table.h
View File

@ -23,6 +23,8 @@
#include "types.h"
#include "originator.h"
#include <linux/if_arp.h>
#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
/**

8
net/batman-adv/packet.h
View File

@ -37,9 +37,15 @@ enum batadv_packettype {
/**
* enum batadv_subtype - packet subtype for unicast4addr
* @BATADV_P_DATA: user payload
* @BATADV_P_DAT_DHT_GET: DHT request message
* @BATADV_P_DAT_DHT_PUT: DHT store message
* @BATADV_P_DAT_CACHE_REPLY: ARP reply generated by DAT
*/
enum batadv_subtype {
BATADV_P_DATA = 0x01,
BATADV_P_DATA = 0x01,
BATADV_P_DAT_DHT_GET = 0x02,
BATADV_P_DAT_DHT_PUT = 0x03,
BATADV_P_DAT_CACHE_REPLY = 0x04,
};
/* this file is included by batctl which needs these defines */