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/* 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, unsigned int protoff, 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 void *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);
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