/* 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...)#endifstatic intmatch(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_expect *exp;	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;	}	exp = ct->master;	READ_LOCK(&ip_conntrack_lock);	if (!exp->expectant) {		DEBUGP("ipt_helper: expectation %p without expectant !?!\n", 			exp);		goto out_unlock;	}	if (!exp->expectant->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", 		exp->expectant->helper->name, info->name);	if (info->name[0] == '\0')		ret ^= 1;	else		ret ^= !strncmp(exp->expectant->helper->name, info->name, 		                strlen(exp->expectant->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){	return ipt_register_match(&helper_match);}static void __exit fini(void){	ipt_unregister_match(&helper_match);}module_init(init);module_exit(fini);