/*
 * 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");