/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NF_QUEUE_H
#define _NF_QUEUE_H

#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>
#include <linux/netfilter.h>
#include <linux/rhashtable-types.h>
#include <linux/skbuff.h>

/* Each queued (to userspace) skbuff has one of these. */
struct nf_queue_entry {
        struct list_head        list;
        struct rhash_head       hash_node;
        struct sk_buff          *skb;
        unsigned int            id;
        unsigned int            hook_index;     /* index in hook_entries->hook[] */
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
        struct net_device       *physin;
        struct net_device       *physout;
#endif
        struct nf_hook_state    state;
        bool                    nf_ct_is_unconfirmed;
        u16                     size; /* sizeof(entry) + saved route keys */
        u16                     queue_num;

        /* extra space to store route keys */
};

#define nf_queue_entry_reroute(x) ((void *)x + sizeof(struct nf_queue_entry))

/* Packet queuing */
struct nf_queue_handler {
        int             (*outfn)(struct nf_queue_entry *entry,
                                 unsigned int queuenum);
        void            (*nf_hook_drop)(struct net *net);
};

void nf_register_queue_handler(const struct nf_queue_handler *qh);
void nf_unregister_queue_handler(void);

bool nf_queue_entry_get_refs(struct nf_queue_entry *entry);
void nf_queue_entry_free(struct nf_queue_entry *entry);

static inline void init_hashrandom(u32 *jhash_initval)
{
        while (*jhash_initval == 0)
                *jhash_initval = get_random_u32();
}

static inline u32 hash_v4(const struct iphdr *iph, u32 initval)
{
        /* packets in either direction go into same queue */
        if ((__force u32)iph->saddr < (__force u32)iph->daddr)
                return jhash_3words((__force u32)iph->saddr,
                        (__force u32)iph->daddr, iph->protocol, initval);

        return jhash_3words((__force u32)iph->daddr,
                        (__force u32)iph->saddr, iph->protocol, initval);
}

static inline u32 hash_v6(const struct ipv6hdr *ip6h, u32 initval)
{
        u32 a, b, c;

        if ((__force u32)ip6h->saddr.s6_addr32[3] <
            (__force u32)ip6h->daddr.s6_addr32[3]) {
                a = (__force u32) ip6h->saddr.s6_addr32[3];
                b = (__force u32) ip6h->daddr.s6_addr32[3];
        } else {
                b = (__force u32) ip6h->saddr.s6_addr32[3];
                a = (__force u32) ip6h->daddr.s6_addr32[3];
        }

        if ((__force u32)ip6h->saddr.s6_addr32[1] <
            (__force u32)ip6h->daddr.s6_addr32[1])
                c = (__force u32) ip6h->saddr.s6_addr32[1];
        else
                c = (__force u32) ip6h->daddr.s6_addr32[1];

        return jhash_3words(a, b, c, initval);
}

static inline u32 hash_bridge(const struct sk_buff *skb, u32 initval)
{
        struct ipv6hdr *ip6h, _ip6h;
        struct iphdr *iph, _iph;

        switch (eth_hdr(skb)->h_proto) {
        case htons(ETH_P_IP):
                iph = skb_header_pointer(skb, skb_network_offset(skb),
                                         sizeof(*iph), &_iph);
                if (iph)
                        return hash_v4(iph, initval);
                break;
        case htons(ETH_P_IPV6):
                ip6h = skb_header_pointer(skb, skb_network_offset(skb),
                                          sizeof(*ip6h), &_ip6h);
                if (ip6h)
                        return hash_v6(ip6h, initval);
                break;
        }

        return 0;
}

static inline u32
nfqueue_hash(const struct sk_buff *skb, u16 queue, u16 queues_total, u8 family,
             u32 initval)
{
        switch (family) {
        case NFPROTO_IPV4:
                queue += reciprocal_scale(hash_v4(ip_hdr(skb), initval),
                                          queues_total);
                break;
        case NFPROTO_IPV6:
                queue += reciprocal_scale(hash_v6(ipv6_hdr(skb), initval),
                                          queues_total);
                break;
        case NFPROTO_BRIDGE:
                queue += reciprocal_scale(hash_bridge(skb, initval),
                                          queues_total);
                break;
        }

        return queue;
}

int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
             unsigned int index, unsigned int verdict);

#endif /* _NF_QUEUE_H */