// SPDX-License-Identifier: GPL-2.0

#include <linux/module.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_ipv4.h>
#include <net/netfilter/nf_tables_ipv6.h>

static unsigned int nft_nat_do_chain(void *priv, struct sk_buff *skb,
                                     const struct nf_hook_state *state)
{
        struct nft_pktinfo pkt;

        nft_set_pktinfo(&pkt, skb, state);

        switch (state->pf) {
#ifdef CONFIG_NF_TABLES_IPV4
        case NFPROTO_IPV4:
                nft_set_pktinfo_ipv4(&pkt);
                break;
#endif
#ifdef CONFIG_NF_TABLES_IPV6
        case NFPROTO_IPV6:
                nft_set_pktinfo_ipv6(&pkt);
                break;
#endif
        default:
                break;
        }

        return nft_do_chain(&pkt, priv);
}

#ifdef CONFIG_NF_TABLES_IPV4
static const struct nft_chain_type nft_chain_nat_ipv4 = {
        .name           = "nat",
        .type           = NFT_CHAIN_T_NAT,
        .family         = NFPROTO_IPV4,
        .owner          = THIS_MODULE,
        .hook_mask      = (1 << NF_INET_PRE_ROUTING) |
                          (1 << NF_INET_POST_ROUTING) |
                          (1 << NF_INET_LOCAL_OUT) |
                          (1 << NF_INET_LOCAL_IN),
        .hooks          = {
                [NF_INET_PRE_ROUTING]   = nft_nat_do_chain,
                [NF_INET_POST_ROUTING]  = nft_nat_do_chain,
                [NF_INET_LOCAL_OUT]     = nft_nat_do_chain,
                [NF_INET_LOCAL_IN]      = nft_nat_do_chain,
        },
        .ops_register = nf_nat_ipv4_register_fn,
        .ops_unregister = nf_nat_ipv4_unregister_fn,
};
#endif

#ifdef CONFIG_NF_TABLES_IPV6
static const struct nft_chain_type nft_chain_nat_ipv6 = {
        .name           = "nat",
        .type           = NFT_CHAIN_T_NAT,
        .family         = NFPROTO_IPV6,
        .owner          = THIS_MODULE,
        .hook_mask      = (1 << NF_INET_PRE_ROUTING) |
                          (1 << NF_INET_POST_ROUTING) |
                          (1 << NF_INET_LOCAL_OUT) |
                          (1 << NF_INET_LOCAL_IN),
        .hooks          = {
                [NF_INET_PRE_ROUTING]   = nft_nat_do_chain,
                [NF_INET_POST_ROUTING]  = nft_nat_do_chain,
                [NF_INET_LOCAL_OUT]     = nft_nat_do_chain,
                [NF_INET_LOCAL_IN]      = nft_nat_do_chain,
        },
        .ops_register           = nf_nat_ipv6_register_fn,
        .ops_unregister         = nf_nat_ipv6_unregister_fn,
};
#endif

#ifdef CONFIG_NF_TABLES_INET
static int nft_nat_inet_reg(struct net *net, const struct nf_hook_ops *ops)
{
        return nf_nat_inet_register_fn(net, ops);
}

static void nft_nat_inet_unreg(struct net *net, const struct nf_hook_ops *ops)
{
        nf_nat_inet_unregister_fn(net, ops);
}

static const struct nft_chain_type nft_chain_nat_inet = {
        .name           = "nat",
        .type           = NFT_CHAIN_T_NAT,
        .family         = NFPROTO_INET,
        .owner          = THIS_MODULE,
        .hook_mask      = (1 << NF_INET_PRE_ROUTING) |
                          (1 << NF_INET_LOCAL_IN) |
                          (1 << NF_INET_LOCAL_OUT) |
                          (1 << NF_INET_POST_ROUTING),
        .hooks          = {
                [NF_INET_PRE_ROUTING]   = nft_nat_do_chain,
                [NF_INET_LOCAL_IN]      = nft_nat_do_chain,
                [NF_INET_LOCAL_OUT]     = nft_nat_do_chain,
                [NF_INET_POST_ROUTING]  = nft_nat_do_chain,
        },
        .ops_register           = nft_nat_inet_reg,
        .ops_unregister         = nft_nat_inet_unreg,
};
#endif

static int __init nft_chain_nat_init(void)
{
#ifdef CONFIG_NF_TABLES_IPV6
        nft_register_chain_type(&nft_chain_nat_ipv6);
#endif
#ifdef CONFIG_NF_TABLES_IPV4
        nft_register_chain_type(&nft_chain_nat_ipv4);
#endif
#ifdef CONFIG_NF_TABLES_INET
        nft_register_chain_type(&nft_chain_nat_inet);
#endif

        return 0;
}

static void __exit nft_chain_nat_exit(void)
{
#ifdef CONFIG_NF_TABLES_IPV4
        nft_unregister_chain_type(&nft_chain_nat_ipv4);
#endif
#ifdef CONFIG_NF_TABLES_IPV6
        nft_unregister_chain_type(&nft_chain_nat_ipv6);
#endif
#ifdef CONFIG_NF_TABLES_INET
        nft_unregister_chain_type(&nft_chain_nat_inet);
#endif
}

module_init(nft_chain_nat_init);
module_exit(nft_chain_nat_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("nftables network address translation support");
#ifdef CONFIG_NF_TABLES_IPV4
MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
#endif
#ifdef CONFIG_NF_TABLES_IPV6
MODULE_ALIAS_NFT_CHAIN(AF_INET6, "nat");
#endif
#ifdef CONFIG_NF_TABLES_INET
MODULE_ALIAS_NFT_CHAIN(1, "nat");       /* NFPROTO_INET */
#endif