/* Redirect.  Simple mapping which alters dst to a local IP address. *//* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2004 Netfilter Core Team <coreteam@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/types.h>#include <linux/ip.h>#include <linux/timer.h>#include <linux/module.h>#include <linux/netfilter.h>#include <linux/netdevice.h>#include <linux/if.h>#include <linux/inetdevice.h>#include <net/protocol.h>#include <net/checksum.h>#include <linux/netfilter_ipv4.h>#include <linux/netfilter_ipv4/ip_nat_rule.h>MODULE_LICENSE("GPL");MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");MODULE_DESCRIPTION("iptables REDIRECT target module");#if 0#define DEBUGP printk#else#define DEBUGP(format, args...)#endif/* FIXME: Take multiple ranges --RR */static intredirect_check(const char *tablename,	       const struct ipt_entry *e,	       void *targinfo,	       unsigned int targinfosize,	       unsigned int hook_mask){	const struct ip_nat_multi_range *mr = targinfo;	if (strcmp(tablename, "nat") != 0) {		DEBUGP("redirect_check: bad table `%s'.\n", table);		return 0;	}	if (targinfosize != IPT_ALIGN(sizeof(*mr))) {		DEBUGP("redirect_check: size %u.\n", targinfosize);		return 0;	}	if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) {		DEBUGP("redirect_check: bad hooks %x.\n", hook_mask);		return 0;	}	if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {		DEBUGP("redirect_check: bad MAP_IPS.\n");		return 0;	}	if (mr->rangesize != 1) {		DEBUGP("redirect_check: bad rangesize %u.\n", mr->rangesize);		return 0;	}	return 1;}static unsigned intredirect_target(struct sk_buff **pskb,		const struct net_device *in,		const struct net_device *out,		unsigned int hooknum,		const void *targinfo,		void *userinfo){	struct ip_conntrack *ct;	enum ip_conntrack_info ctinfo;	u_int32_t newdst;	const struct ip_nat_multi_range *mr = targinfo;	struct ip_nat_multi_range newrange;	IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING		     || hooknum == NF_IP_LOCAL_OUT);	ct = ip_conntrack_get(*pskb, &ctinfo);	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));	/* Local packets: make them go to loopback */	if (hooknum == NF_IP_LOCAL_OUT)		newdst = htonl(0x7F000001);	else {		struct in_device *indev;		/* Device might not have an associated in_device. */		indev = (struct in_device *)(*pskb)->dev->ip_ptr;		if (indev == NULL || indev->ifa_list == NULL)			return NF_DROP;		/* Grab first address on interface. */		newdst = indev->ifa_list->ifa_local;	}	/* Transfer from original range. */	newrange = ((struct ip_nat_multi_range)		{ 1, { { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,			 newdst, newdst,			 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 redirect_reg = {	.name		= "REDIRECT",	.target		= redirect_target,	.checkentry	= redirect_check,	.me		= THIS_MODULE,};static int __init init(void){	return ipt_register_target(&redirect_reg);}static void __exit fini(void){	ipt_unregister_target(&redirect_reg);}module_init(init);module_exit(fini);