/* 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 */