// SPDX-License-Identifier: GPL-2.0-only

  /* Masquerade.  Simple mapping which alters range to a local IP address
     (depending on route). */
  
  /* (C) 1999-2001 Paul `Rusty' Russell

   * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>

  #include <linux/netfilter/x_tables.h>

  #include <net/netfilter/nf_nat.h>

  #include <net/netfilter/nf_nat_masquerade.h>

  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");

  MODULE_DESCRIPTION("Xtables: automatic-address SNAT");

  /* FIXME: Multiple targets. --RR */

  static int masquerade_tg_check(const struct xt_tgchk_param *par)

  {

  	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;

  	if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {

  		pr_debug("bad MAP_IPS.
  ");

  		return -EINVAL;

  	}
  	if (mr->rangesize != 1) {

  		pr_debug("bad rangesize %u
  ", mr->rangesize);

  		return -EINVAL;

  	}

  	return nf_ct_netns_get(par->net, par->family);

  }
  
  static unsigned int

  masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)

  {

  	struct nf_nat_range2 range;

  	const struct nf_nat_ipv4_multi_range_compat *mr;

  	mr = par->targinfo;

  	range.flags = mr->range[0].flags;
  	range.min_proto = mr->range[0].min;
  	range.max_proto = mr->range[0].max;

  	return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), &range,
  				      xt_out(par));

  }

  static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
  {
  	nf_ct_netns_put(par->net, par->family);
  }

  #if IS_ENABLED(CONFIG_IPV6)
  static unsigned int
  masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  {
  	return nf_nat_masquerade_ipv6(skb, par->targinfo, xt_out(par));
  }
  
  static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par)
  {
  	const struct nf_nat_range2 *range = par->targinfo;
  
  	if (range->flags & NF_NAT_RANGE_MAP_IPS)
  		return -EINVAL;
  
  	return nf_ct_netns_get(par->net, par->family);
  }
  #endif
  
  static struct xt_target masquerade_tg_reg[] __read_mostly = {
  	{
  #if IS_ENABLED(CONFIG_IPV6)
  		.name		= "MASQUERADE",
  		.family		= NFPROTO_IPV6,
  		.target		= masquerade_tg6,
  		.targetsize	= sizeof(struct nf_nat_range),
  		.table		= "nat",
  		.hooks		= 1 << NF_INET_POST_ROUTING,
  		.checkentry	= masquerade_tg6_checkentry,
  		.destroy	= masquerade_tg_destroy,
  		.me		= THIS_MODULE,
  	}, {
  #endif
  		.name		= "MASQUERADE",
  		.family		= NFPROTO_IPV4,
  		.target		= masquerade_tg,
  		.targetsize	= sizeof(struct nf_nat_ipv4_multi_range_compat),
  		.table		= "nat",
  		.hooks		= 1 << NF_INET_POST_ROUTING,
  		.checkentry	= masquerade_tg_check,
  		.destroy	= masquerade_tg_destroy,
  		.me		= THIS_MODULE,
  	}

  };

  static int __init masquerade_tg_init(void)

  {
  	int ret;

  	ret = xt_register_targets(masquerade_tg_reg,
  				  ARRAY_SIZE(masquerade_tg_reg));

  	if (ret)
  		return ret;

  	ret = nf_nat_masquerade_inet_register_notifiers();

  	if (ret) {
  		xt_unregister_targets(masquerade_tg_reg,
  				      ARRAY_SIZE(masquerade_tg_reg));
  		return ret;
  	}

  
  	return ret;
  }

  static void __exit masquerade_tg_exit(void)

  {

  	xt_unregister_targets(masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg));

  	nf_nat_masquerade_inet_unregister_notifiers();

  }

  module_init(masquerade_tg_init);
  module_exit(masquerade_tg_exit);

  #if IS_ENABLED(CONFIG_IPV6)
  MODULE_ALIAS("ip6t_MASQUERADE");
  #endif
  MODULE_ALIAS("ipt_MASQUERADE");