/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the BSD Socket
 *              interface as the means of communication with the user level.
 *
 * Authors:     Lotsa people, from code originally in tcp
 */

#ifndef _INET6_HASHTABLES_H
#define _INET6_HASHTABLES_H


#if IS_ENABLED(CONFIG_IPV6)
#include <linux/in6.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <linux/jhash.h>

#include <net/inet_sock.h>

#include <net/ipv6.h>
#include <net/netns/hash.h>

struct inet_hashinfo;

static inline unsigned int __inet6_ehashfn(const u32 lhash,
                                    const u16 lport,
                                    const u32 fhash,
                                    const __be16 fport,
                                    const u32 initval)
{
        const u32 ports = (((u32)lport) << 16) | (__force u32)fport;
        return jhash_3words(lhash, fhash, ports, initval);
}

/*
 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
 * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
 *
 * The sockhash lock must be held as a reader here.
 */
struct sock *__inet6_lookup_established(const struct net *net,
                                        const struct in6_addr *saddr,
                                        const __be16 sport,
                                        const struct in6_addr *daddr,
                                        const u16 hnum, const int dif,
                                        const int sdif);

typedef u32 (inet6_ehashfn_t)(const struct net *net,
                               const struct in6_addr *laddr, const u16 lport,
                               const struct in6_addr *faddr, const __be16 fport);

inet6_ehashfn_t inet6_ehashfn;

INDIRECT_CALLABLE_DECLARE(inet6_ehashfn_t udp6_ehashfn);

struct sock *inet6_lookup_reuseport(const struct net *net, struct sock *sk,
                                    struct sk_buff *skb, int doff,
                                    const struct in6_addr *saddr,
                                    __be16 sport,
                                    const struct in6_addr *daddr,
                                    unsigned short hnum,
                                    inet6_ehashfn_t *ehashfn);

struct sock *inet6_lookup_listener(const struct net *net,
                                   struct sk_buff *skb, int doff,
                                   const struct in6_addr *saddr,
                                   const __be16 sport,
                                   const struct in6_addr *daddr,
                                   const unsigned short hnum,
                                   const int dif, const int sdif);

struct sock *inet6_lookup_run_sk_lookup(const struct net *net,
                                        int protocol,
                                        struct sk_buff *skb, int doff,
                                        const struct in6_addr *saddr,
                                        const __be16 sport,
                                        const struct in6_addr *daddr,
                                        const u16 hnum, const int dif,
                                        inet6_ehashfn_t *ehashfn);

static inline struct sock *__inet6_lookup(const struct net *net,
                                          struct sk_buff *skb, int doff,
                                          const struct in6_addr *saddr,
                                          const __be16 sport,
                                          const struct in6_addr *daddr,
                                          const u16 hnum,
                                          const int dif, const int sdif,
                                          bool *refcounted)
{
        struct sock *sk = __inet6_lookup_established(net, saddr, sport,
                                                     daddr, hnum,
                                                     dif, sdif);
        *refcounted = true;
        if (sk)
                return sk;
        *refcounted = false;
        return inet6_lookup_listener(net, skb, doff, saddr, sport,
                                     daddr, hnum, dif, sdif);
}

static inline
struct sock *inet6_steal_sock(struct net *net, struct sk_buff *skb, int doff,
                              const struct in6_addr *saddr, const __be16 sport,
                              const struct in6_addr *daddr, const __be16 dport,
                              bool *refcounted, inet6_ehashfn_t *ehashfn)
{
        struct sock *sk, *reuse_sk;
        bool prefetched;

        sk = skb_steal_sock(skb, refcounted, &prefetched);
        if (!sk)
                return NULL;

        if (!prefetched || !sk_fullsock(sk))
                return sk;

        if (sk->sk_protocol == IPPROTO_TCP) {
                if (sk->sk_state != TCP_LISTEN)
                        return sk;
        } else if (sk->sk_protocol == IPPROTO_UDP) {
                if (sk->sk_state != TCP_CLOSE)
                        return sk;
        } else {
                return sk;
        }

        reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff,
                                          saddr, sport, daddr, ntohs(dport),
                                          ehashfn);
        if (!reuse_sk)
                return sk;

        /* We've chosen a new reuseport sock which is never refcounted. This
         * implies that sk also isn't refcounted.
         */
        WARN_ON_ONCE(*refcounted);

        return reuse_sk;
}

static inline struct sock *__inet6_lookup_skb(struct sk_buff *skb, int doff,
                                              const __be16 sport,
                                              const __be16 dport,
                                              int iif, int sdif,
                                              bool *refcounted)
{
        struct net *net = skb_dst_dev_net_rcu(skb);
        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
        struct sock *sk;

        sk = inet6_steal_sock(net, skb, doff, &ip6h->saddr, sport, &ip6h->daddr, dport,
                              refcounted, inet6_ehashfn);
        if (IS_ERR(sk))
                return NULL;
        if (sk)
                return sk;

        return __inet6_lookup(net, skb, doff, &ip6h->saddr, sport,
                              &ip6h->daddr, ntohs(dport),
                              iif, sdif, refcounted);
}

struct sock *inet6_lookup(const struct net *net, struct sk_buff *skb, int doff,
                          const struct in6_addr *saddr, const __be16 sport,
                          const struct in6_addr *daddr, const __be16 dport,
                          const int dif);

static inline bool inet6_match(const struct net *net, const struct sock *sk,
                               const struct in6_addr *saddr,
                               const struct in6_addr *daddr,
                               const __portpair ports,
                               const int dif, const int sdif)
{
        if (!net_eq(sock_net(sk), net) ||
            sk->sk_family != AF_INET6 ||
            READ_ONCE(sk->sk_portpair) != ports ||
            !ipv6_addr_equal(&sk->sk_v6_daddr, saddr) ||
            !ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
                return false;

        /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
        return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
                                    sdif);
}
#endif /* IS_ENABLED(CONFIG_IPV6) */

#endif /* _INET6_HASHTABLES_H */