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/* iptables module to match on related connections */
/*
* (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
*
* 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.
*
* 19 Mar 2002 Harald Welte <laforge@gnumonks.org>:
* - Port to newnat infrastructure
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_helper.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
MODULE_DESCRIPTION("iptables helper match module");
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
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_helper_info *info = matchinfo;
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
int ret = info->invert;
ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
if (!ct) {
DEBUGP("ipt_helper: Eek! invalid conntrack?\n");
return ret;
}
if (!ct->master) {
DEBUGP("ipt_helper: conntrack %p has no master\n", ct);
return ret;
}
READ_LOCK(&ip_conntrack_lock);
if (!ct->master->helper) {
DEBUGP("ipt_helper: master ct %p has no helper\n",
exp->expectant);
goto out_unlock;
}
DEBUGP("master's name = %s , info->name = %s\n",
ct->master->helper->name, info->name);
if (info->name[0] == '\0')
ret ^= 1;
else
ret ^= !strncmp(ct->master->helper->name, info->name,
strlen(ct->master->helper->name));
out_unlock:
READ_UNLOCK(&ip_conntrack_lock);
return ret;
}
static int check(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
struct ipt_helper_info *info = matchinfo;
info->name[29] = '\0';
/* verify size */
if (matchsize != IPT_ALIGN(sizeof(struct ipt_helper_info)))
return 0;
return 1;
}
static struct ipt_match helper_match = {
.name = "helper",
.match = &match,
.checkentry = &check,
.me = THIS_MODULE,
};
static int __init init(void)
{
need_ip_conntrack();
return ipt_register_match(&helper_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&helper_match);
}
module_init(init);
module_exit(fini);
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