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/*
* ebt_arpreply
*
* Authors:
* Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
* Bart De Schuymer <bdschuym@pandora.be>
*
* August, 2003
*
*/
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_arpreply.h>
#include <linux/if_arp.h>
#include <linux/module.h>
static int ebt_target_reply(struct sk_buff **pskb, unsigned int hooknr,
const struct net_device *in, const struct net_device *out,
const void *data, unsigned int datalen)
{
struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data;
struct arphdr *ah;
unsigned char *sha, *arp_ptr;
u32 sip, tip;
ah = (**pskb).nh.arph;
if (ah->ar_op != __constant_htons(ARPOP_REQUEST) ||
ah->ar_hln != ETH_ALEN || ah->ar_pro != htons(ETH_P_IP) ||
ah->ar_pln != 4)
return EBT_CONTINUE;
arp_ptr = (unsigned char *)(ah + 1);
/* get source and target IP */
sha = arp_ptr;
arp_ptr += ETH_ALEN;
memcpy(&sip, arp_ptr, 4);
arp_ptr += 4 + ETH_ALEN;
memcpy(&tip, arp_ptr, 4);
arp_send(ARPOP_REPLY, ETH_P_ARP, sip, in, tip, sha, info->mac, sha);
return info->target;
}
static int ebt_target_reply_check(const char *tablename, unsigned int hookmask,
const struct ebt_entry *e, void *data, unsigned int datalen)
{
struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data;
if (datalen != EBT_ALIGN(sizeof(struct ebt_arpreply_info)))
return -EINVAL;
if (BASE_CHAIN && info->target == EBT_RETURN)
return -EINVAL;
if (e->ethproto != __constant_htons(ETH_P_ARP) ||
e->invflags & EBT_IPROTO)
return -EINVAL;
CLEAR_BASE_CHAIN_BIT;
if (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING))
return -EINVAL;
return 0;
}
static struct ebt_target reply_target =
{
.name = EBT_ARPREPLY_TARGET,
.target = ebt_target_reply,
.check = ebt_target_reply_check,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ebt_register_target(&reply_target);
}
static void __exit fini(void)
{
ebt_unregister_target(&reply_target);
}
module_init(init);
module_exit(fini);
EXPORT_NO_SYMBOLS;
MODULE_LICENSE("GPL");
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