?? ebt_arpreply.c
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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 <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");
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