/* IP tables module for matching the value of the TTL  * * ipt_ttl.c,v 1.5 2000/11/13 11:16:08 laforge Exp * * (C) 2000,2001 by Harald Welte <laforge@netfilter.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */#include <linux/module.h>#include <linux/skbuff.h>#include <linux/netfilter_ipv4/ipt_ttl.h>#include <linux/netfilter_ipv4/ip_tables.h>MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");MODULE_DESCRIPTION("IP tables TTL matching module");MODULE_LICENSE("GPL");static int match(const struct sk_buff *skb, const struct net_device *in,		 const struct net_device *out, const void *matchinfo,		 int offset, int *hotdrop){	const struct ipt_ttl_info *info = matchinfo;	switch (info->mode) {		case IPT_TTL_EQ:			return (skb->nh.iph->ttl == info->ttl);			break;		case IPT_TTL_NE:			return (!(skb->nh.iph->ttl == info->ttl));			break;		case IPT_TTL_LT:			return (skb->nh.iph->ttl < info->ttl);			break;		case IPT_TTL_GT:			return (skb->nh.iph->ttl > info->ttl);			break;		default:			printk(KERN_WARNING "ipt_ttl: unknown mode %d\n", 				info->mode);			return 0;	}	return 0;}static int checkentry(const char *tablename, const struct ipt_ip *ip,		      void *matchinfo, unsigned int matchsize,		      unsigned int hook_mask){	if (matchsize != IPT_ALIGN(sizeof(struct ipt_ttl_info)))		return 0;	return 1;}static struct ipt_match ttl_match = {	.name		= "ttl",	.match		= &match,	.checkentry	= &checkentry,	.me		= THIS_MODULE,};static int __init init(void){	return ipt_register_match(&ttl_match);}static void __exit fini(void){	ipt_unregister_match(&ttl_match);}module_init(init);module_exit(fini);