/*

   * Copyright (c) 2014 Arturo Borrero Gonzalez <arturo@debian.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/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>
  #include <net/netfilter/nft_masq.h>
  #include <net/netfilter/ipv4/nf_nat_masquerade.h>
  
  static void nft_masq_ipv4_eval(const struct nft_expr *expr,

  			       struct nft_regs *regs,

  			       const struct nft_pktinfo *pkt)
  {
  	struct nft_masq *priv = nft_expr_priv(expr);
  	struct nf_nat_range range;

  	memset(&range, 0, sizeof(range));

  	range.flags = priv->flags;

  	if (priv->sreg_proto_min) {

  		range.min_proto.all = (__force __be16)nft_reg_load16(
  			&regs->data[priv->sreg_proto_min]);
  		range.max_proto.all = (__force __be16)nft_reg_load16(
  			&regs->data[priv->sreg_proto_max]);

  	}

  	regs->verdict.code = nf_nat_masquerade_ipv4(pkt->skb, nft_hook(pkt),
  						    &range, nft_out(pkt));

  }

  static void
  nft_masq_ipv4_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
  {
  	nf_ct_netns_put(ctx->net, NFPROTO_IPV4);
  }

  static struct nft_expr_type nft_masq_ipv4_type;
  static const struct nft_expr_ops nft_masq_ipv4_ops = {
  	.type		= &nft_masq_ipv4_type,
  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_masq)),
  	.eval		= nft_masq_ipv4_eval,

  	.init		= nft_masq_init,

  	.destroy	= nft_masq_ipv4_destroy,

  	.dump		= nft_masq_dump,

  	.validate	= nft_masq_validate,

  };
  
  static struct nft_expr_type nft_masq_ipv4_type __read_mostly = {
  	.family		= NFPROTO_IPV4,
  	.name		= "masq",
  	.ops		= &nft_masq_ipv4_ops,
  	.policy		= nft_masq_policy,
  	.maxattr	= NFTA_MASQ_MAX,
  	.owner		= THIS_MODULE,
  };
  
  static int __init nft_masq_ipv4_module_init(void)
  {

  	int ret;
  
  	ret = nft_register_expr(&nft_masq_ipv4_type);
  	if (ret < 0)
  		return ret;
  
  	nf_nat_masquerade_ipv4_register_notifier();
  
  	return ret;

  }
  
  static void __exit nft_masq_ipv4_module_exit(void)
  {
  	nft_unregister_expr(&nft_masq_ipv4_type);

  	nf_nat_masquerade_ipv4_unregister_notifier();

  }
  
  module_init(nft_masq_ipv4_module_init);
  module_exit(nft_masq_ipv4_module_exit);
  
  MODULE_LICENSE("GPL");

  MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo@debian.org");

  MODULE_ALIAS_NFT_AF_EXPR(AF_INET, "masq");