/* *  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 <net/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;	u32 sip, dip;	struct arphdr ah;	unsigned char sha[ETH_ALEN];	struct sk_buff *skb = *pskb;	if (skb_copy_bits(skb, 0, &ah, sizeof(ah)))		return EBT_DROP;	if (ah.ar_op != __constant_htons(ARPOP_REQUEST) || ah.ar_hln != ETH_ALEN	    || ah.ar_pro != __constant_htons(ETH_P_IP) || ah.ar_pln != 4)		return EBT_CONTINUE;	if (skb_copy_bits(skb, sizeof(ah), &sha, ETH_ALEN))		return EBT_DROP;	if (skb_copy_bits(skb, sizeof(ah) + ETH_ALEN, &sip, sizeof(sip)))		return EBT_DROP;	if (skb_copy_bits(skb, sizeof(ah) + 2 * ETH_ALEN + sizeof(sip),	    &dip, sizeof(dip)))		return EBT_DROP;	arp_send(ARPOP_REPLY, ETH_P_ARP, sip, (struct net_device *)in,	         dip, 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);MODULE_LICENSE("GPL");