// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/rhashtable.h>
#include <net/netfilter/nf_flow_table.h>
#include <net/netfilter/nf_tables.h>
#include <linux/if_vlan.h>

static unsigned int
nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb,
                          const struct nf_hook_state *state)
{
        struct vlan_ethhdr *veth;
        __be16 proto;

        switch (skb->protocol) {
        case htons(ETH_P_8021Q):
                if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)))
                        return NF_ACCEPT;

                veth = (struct vlan_ethhdr *)skb_mac_header(skb);
                proto = veth->h_vlan_encapsulated_proto;
                break;
        case htons(ETH_P_PPP_SES):
                if (!nf_flow_pppoe_proto(skb, &proto))
                        return NF_ACCEPT;
                break;
        default:
                proto = skb->protocol;
                break;
        }

        switch (proto) {
        case htons(ETH_P_IP):
                return nf_flow_offload_ip_hook(priv, skb, state);
        case htons(ETH_P_IPV6):
                return nf_flow_offload_ipv6_hook(priv, skb, state);
        }

        return NF_ACCEPT;
}

static int nf_flow_rule_route_inet(struct net *net,
                                   struct flow_offload *flow,
                                   enum flow_offload_tuple_dir dir,
                                   struct nf_flow_rule *flow_rule)
{
        const struct flow_offload_tuple *flow_tuple = &flow->tuplehash[dir].tuple;
        int err;

        switch (flow_tuple->l3proto) {
        case NFPROTO_IPV4:
                err = nf_flow_rule_route_ipv4(net, flow, dir, flow_rule);
                break;
        case NFPROTO_IPV6:
                err = nf_flow_rule_route_ipv6(net, flow, dir, flow_rule);
                break;
        default:
                err = -1;
                break;
        }

        return err;
}

static struct nf_flowtable_type flowtable_inet = {
        .family         = NFPROTO_INET,
        .init           = nf_flow_table_init,
        .setup          = nf_flow_table_offload_setup,
        .action         = nf_flow_rule_route_inet,
        .free           = nf_flow_table_free,
        .hook           = nf_flow_offload_inet_hook,
        .owner          = THIS_MODULE,
};

static struct nf_flowtable_type flowtable_ipv4 = {
        .family         = NFPROTO_IPV4,
        .init           = nf_flow_table_init,
        .setup          = nf_flow_table_offload_setup,
        .action         = nf_flow_rule_route_ipv4,
        .free           = nf_flow_table_free,
        .hook           = nf_flow_offload_ip_hook,
        .owner          = THIS_MODULE,
};

static struct nf_flowtable_type flowtable_ipv6 = {
        .family         = NFPROTO_IPV6,
        .init           = nf_flow_table_init,
        .setup          = nf_flow_table_offload_setup,
        .action         = nf_flow_rule_route_ipv6,
        .free           = nf_flow_table_free,
        .hook           = nf_flow_offload_ipv6_hook,
        .owner          = THIS_MODULE,
};

static int __init nf_flow_inet_module_init(void)
{
        nft_register_flowtable_type(&flowtable_ipv4);
        nft_register_flowtable_type(&flowtable_ipv6);
        nft_register_flowtable_type(&flowtable_inet);

        return 0;
}

static void __exit nf_flow_inet_module_exit(void)
{
        nft_unregister_flowtable_type(&flowtable_inet);
        nft_unregister_flowtable_type(&flowtable_ipv6);
        nft_unregister_flowtable_type(&flowtable_ipv4);
}

module_init(nf_flow_inet_module_init);
module_exit(nf_flow_inet_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
MODULE_ALIAS_NF_FLOWTABLE(AF_INET);
MODULE_ALIAS_NF_FLOWTABLE(AF_INET6);
MODULE_ALIAS_NF_FLOWTABLE(1); /* NFPROTO_INET */
MODULE_DESCRIPTION("Netfilter flow table mixed IPv4/IPv6 module");