[deliverable/linux.git] / net / ipv4 / netfilter / ipt_NETMAP.c

/* NETMAP - static NAT mapping of IP network addresses (1:1).
 * The mapping can be applied to source (POSTROUTING),
 * destination (PREROUTING), or both (with separate rules).
 */

/* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
 *
 * 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/ip.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>

#define MODULENAME "NETMAP"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

static int
check(const char *tablename,
      const void *e,
      const struct xt_target *target,
      void *targinfo,
      unsigned int hook_mask)
{
	const struct ip_nat_multi_range_compat *mr = targinfo;

	if (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) {
		DEBUGP(MODULENAME":check: bad MAP_IPS.\n");
		return 0;
	}
	if (mr->rangesize != 1) {
		DEBUGP(MODULENAME":check: bad rangesize %u.\n", mr->rangesize);
		return 0;
	}
	return 1;
}

static unsigned int
target(struct sk_buff **pskb,
       const struct net_device *in,
       const struct net_device *out,
       unsigned int hooknum,
       const struct xt_target *target,
       const void *targinfo)
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	__be32 new_ip, netmask;
	const struct ip_nat_multi_range_compat *mr = targinfo;
	struct ip_nat_range newrange;

	IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
		     || hooknum == NF_IP_POST_ROUTING
		     || hooknum == NF_IP_LOCAL_OUT);
	ct = ip_conntrack_get(*pskb, &ctinfo);

	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);

	if (hooknum == NF_IP_PRE_ROUTING || hooknum == NF_IP_LOCAL_OUT)
		new_ip = (*pskb)->nh.iph->daddr & ~netmask;
	else
		new_ip = (*pskb)->nh.iph->saddr & ~netmask;
	new_ip |= mr->range[0].min_ip & netmask;

	newrange = ((struct ip_nat_range)
		{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
		  new_ip, new_ip,
		  mr->range[0].min, mr->range[0].max });

	/* Hand modified range to generic setup. */
	return ip_nat_setup_info(ct, &newrange, hooknum);
}

static struct ipt_target target_module = { 
	.name 		= MODULENAME,
	.target 	= target, 
	.targetsize	= sizeof(struct ip_nat_multi_range_compat),
	.table		= "nat",
	.hooks		= (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_POST_ROUTING) |
			  (1 << NF_IP_LOCAL_OUT),
	.checkentry 	= check,
    	.me 		= THIS_MODULE 
};

static int __init ipt_netmap_init(void)
{
	return ipt_register_target(&target_module);
}

static void __exit ipt_netmap_fini(void)
{
	ipt_unregister_target(&target_module);
}

module_init(ipt_netmap_init);
module_exit(ipt_netmap_fini);
Commit	Line	Data
1da177e4 LT	1	/* NETMAP - static NAT mapping of IP network addresses (1:1).
	2	* The mapping can be applied to source (POSTROUTING),
	3	* destination (PREROUTING), or both (with separate rules).
	4	*/
	5
	6	/* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*/
	12
1da177e4 LT	13	#include <linux/ip.h>
	14	#include <linux/module.h>
	15	#include <linux/netdevice.h>
	16	#include <linux/netfilter.h>
	17	#include <linux/netfilter_ipv4.h>
	18	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	19
	20	#define MODULENAME "NETMAP"
	21	MODULE_LICENSE("GPL");
	22	MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
	23	MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
	24
	25	#if 0
	26	#define DEBUGP printk
	27	#else
	28	#define DEBUGP(format, args...)
	29	#endif
	30
	31	static int
	32	check(const char *tablename,
2e4e6a17	33	const void *e,
c4986734	34	const struct xt_target *target,
1da177e4	35	void *targinfo,
1da177e4 LT	36	unsigned int hook_mask)
	37	{
	38	const struct ip_nat_multi_range_compat *mr = targinfo;
	39
1da177e4 LT	40	if (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) {
	41	DEBUGP(MODULENAME":check: bad MAP_IPS.\n");
	42	return 0;
	43	}
	44	if (mr->rangesize != 1) {
	45	DEBUGP(MODULENAME":check: bad rangesize %u.\n", mr->rangesize);
	46	return 0;
	47	}
	48	return 1;
	49	}
	50
	51	static unsigned int
	52	target(struct sk_buff **pskb,
	53	const struct net_device *in,
	54	const struct net_device *out,
	55	unsigned int hooknum,
c4986734	56	const struct xt_target *target,
fe1cb108	57	const void *targinfo)
1da177e4 LT	58	{
	59	struct ip_conntrack *ct;
	60	enum ip_conntrack_info ctinfo;
6a19d614	61	__be32 new_ip, netmask;
1da177e4 LT	62	const struct ip_nat_multi_range_compat *mr = targinfo;
	63	struct ip_nat_range newrange;
	64
	65	IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
000efe1d GWS	66	\|\| hooknum == NF_IP_POST_ROUTING
000efe1d GWS	67	\|\| hooknum == NF_IP_LOCAL_OUT);
1da177e4 LT	68	ct = ip_conntrack_get(*pskb, &ctinfo);
	69
	70	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
	71
000efe1d	72	if (hooknum == NF_IP_PRE_ROUTING \|\| hooknum == NF_IP_LOCAL_OUT)
1da177e4 LT	73	new_ip = (*pskb)->nh.iph->daddr & ~netmask;
	74	else
	75	new_ip = (*pskb)->nh.iph->saddr & ~netmask;
	76	new_ip \|= mr->range[0].min_ip & netmask;
	77
	78	newrange = ((struct ip_nat_range)
	79	{ mr->range[0].flags \| IP_NAT_RANGE_MAP_IPS,
	80	new_ip, new_ip,
	81	mr->range[0].min, mr->range[0].max });
	82
	83	/* Hand modified range to generic setup. */
	84	return ip_nat_setup_info(ct, &newrange, hooknum);
	85	}
	86
	87	static struct ipt_target target_module = {
	88	.name = MODULENAME,
	89	.target = target,
1d5cd909 PM	90	.targetsize = sizeof(struct ip_nat_multi_range_compat),
	91	.table = "nat",
	92	.hooks = (1 << NF_IP_PRE_ROUTING) \| (1 << NF_IP_POST_ROUTING) \|
	93	(1 << NF_IP_LOCAL_OUT),
1da177e4 LT	94	.checkentry = check,
	95	.me = THIS_MODULE
	96	};
	97
65b4b4e8	98	static int __init ipt_netmap_init(void)
1da177e4 LT	99	{
	100	return ipt_register_target(&target_module);
	101	}
	102
65b4b4e8	103	static void __exit ipt_netmap_fini(void)
1da177e4 LT	104	{
	105	ipt_unregister_target(&target_module);
	106	}
	107
65b4b4e8 AM	108	module_init(ipt_netmap_init);
65b4b4e8 AM	109	module_exit(ipt_netmap_fini);