/*
   * 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.
   *
   *		Generic INET6 transport hashtables
   *

   * Authors:	Lotsa people, from code originally in tcp, generalised here

   *		by Arnaldo Carvalho de Melo <acme@mandriva.com>

   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */

  #include <linux/module.h>

  #include <linux/random.h>

  #include <net/addrconf.h>

  #include <net/inet_connection_sock.h>
  #include <net/inet_hashtables.h>
  #include <net/inet6_hashtables.h>

  #include <net/secure_seq.h>

  #include <net/ip.h>

  #include <net/sock_reuseport.h>

  u32 inet6_ehashfn(const struct net *net,
  		  const struct in6_addr *laddr, const u16 lport,
  		  const struct in6_addr *faddr, const __be16 fport)

  {

  	static u32 inet6_ehash_secret __read_mostly;
  	static u32 ipv6_hash_secret __read_mostly;
  
  	u32 lhash, fhash;
  
  	net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  	net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  
  	lhash = (__force u32)laddr->s6_addr32[3];
  	fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);

  	return __inet6_ehashfn(lhash, lport, fhash, fport,

  			       inet6_ehash_secret + net_hash_mix(net));

  }

  /*
   * 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(struct net *net,
  					struct inet_hashinfo *hashinfo,

  					   const struct in6_addr *saddr,

  					   const __be16 sport,

  					   const struct in6_addr *daddr,
  					   const u16 hnum,

  					   const int dif, const int sdif)

  {
  	struct sock *sk;

  	const struct hlist_nulls_node *node;

  	const __portpair ports = INET_COMBINED_PORTS(sport, hnum);

  	/* Optimize here for direct hit, only listening connections can
  	 * have wildcards anyways.
  	 */

  	unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);

  	unsigned int slot = hash & hashinfo->ehash_mask;

  	struct inet_ehash_bucket *head = &hashinfo->ehash[slot];

  begin:
  	sk_nulls_for_each_rcu(sk, node, &head->chain) {

  		if (sk->sk_hash != hash)
  			continue;

  		if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))

  			continue;

  		if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))

  			goto out;

  		if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))) {

  			sock_gen_put(sk);
  			goto begin;

  		}

  		goto found;

  	}

  	if (get_nulls_value(node) != slot)
  		goto begin;

  out:

  	sk = NULL;
  found:

  	return sk;
  }
  EXPORT_SYMBOL(__inet6_lookup_established);

  static inline int compute_score(struct sock *sk, struct net *net,

  				const unsigned short hnum,
  				const struct in6_addr *daddr,

  				const int dif, const int sdif, bool exact_dif)

  {
  	int score = -1;

  	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&

  	    sk->sk_family == PF_INET6) {

  
  		score = 1;

  		if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
  			if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))

  				return -1;
  			score++;
  		}

  		if (sk->sk_bound_dev_if || exact_dif) {

  			bool dev_match = (sk->sk_bound_dev_if == dif ||
  					  sk->sk_bound_dev_if == sdif);

  			if (!dev_match)

  				return -1;

  			if (sk->sk_bound_dev_if)

  				score++;

  		}

  		if (sk->sk_incoming_cpu == raw_smp_processor_id())
  			score++;

  	}
  	return score;
  }

  /* called with rcu_read_lock() */

  struct sock *inet6_lookup_listener(struct net *net,

  		struct inet_hashinfo *hashinfo,
  		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)

  {

  	unsigned int hash = inet_lhashfn(net, hnum);
  	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];

  	int score, hiscore = 0, matches = 0, reuseport = 0;

  	bool exact_dif = inet6_exact_dif_match(net, skb);

  	struct sock *sk, *result = NULL;
  	u32 phash = 0;

  	sk_for_each(sk, &ilb->head) {

  		score = compute_score(sk, net, hnum, daddr, dif, sdif, exact_dif);

  		if (score > hiscore) {

  			reuseport = sk->sk_reuseport;

  			if (reuseport) {
  				phash = inet6_ehashfn(net, daddr, hnum,
  						      saddr, sport);

  				result = reuseport_select_sock(sk, phash,
  							       skb, doff);
  				if (result)
  					return result;

  				matches = 1;
  			}

  			result = sk;

  			hiscore = score;

  		} else if (score == hiscore && reuseport) {
  			matches++;

  			if (reciprocal_scale(phash, matches) == 0)

  				result = sk;
  			phash = next_pseudo_random32(phash);

  		}
  	}

  	return result;
  }

  EXPORT_SYMBOL_GPL(inet6_lookup_listener);

  struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,

  			  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)
  {
  	struct sock *sk;

  	bool refcounted;

  	sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,

  			    ntohs(dport), dif, 0, &refcounted);

  	if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))

  		sk = NULL;

  	return sk;
  }

  EXPORT_SYMBOL_GPL(inet6_lookup);

  
  static int __inet6_check_established(struct inet_timewait_death_row *death_row,
  				     struct sock *sk, const __u16 lport,
  				     struct inet_timewait_sock **twp)
  {
  	struct inet_hashinfo *hinfo = death_row->hashinfo;

  	struct inet_sock *inet = inet_sk(sk);

  	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
  	const struct in6_addr *saddr = &sk->sk_v6_daddr;

  	const int dif = sk->sk_bound_dev_if;

  	struct net *net = sock_net(sk);

  	const int sdif = l3mdev_master_ifindex_by_index(net, dif);
  	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);

  	const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,

  						inet->inet_dport);

  	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);

  	spinlock_t *lock = inet_ehash_lockp(hinfo, hash);

  	struct sock *sk2;

  	const struct hlist_nulls_node *node;

  	struct inet_timewait_sock *tw = NULL;

  	spin_lock(lock);

  	sk_nulls_for_each(sk2, node, &head->chain) {

  		if (sk2->sk_hash != hash)
  			continue;

  		if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports,
  				       dif, sdif))) {

  			if (sk2->sk_state == TCP_TIME_WAIT) {

  				tw = inet_twsk(sk2);
  				if (twsk_unique(sk, sk2, twp))

  					break;

  			}

  			goto not_unique;

  		}

  	}

  	/* Must record num and sport now. Otherwise we will see

  	 * in hash table socket with a funny identity.
  	 */

  	inet->inet_num = lport;
  	inet->inet_sport = htons(lport);

  	sk->sk_hash = hash;

  	WARN_ON(!sk_unhashed(sk));

  	__sk_nulls_add_node_rcu(sk, &head->chain);

  	if (tw) {

  		sk_nulls_del_node_init_rcu((struct sock *)tw);

  		__NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);

  	}

  	spin_unlock(lock);

  	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

  	if (twp) {

  		*twp = tw;

  	} else if (tw) {

  		/* Silly. Should hash-dance instead... */

  		inet_twsk_deschedule_put(tw);

  	}
  	return 0;
  
  not_unique:

  	spin_unlock(lock);

  	return -EADDRNOTAVAIL;
  }

  static u32 inet6_sk_port_offset(const struct sock *sk)

  {
  	const struct inet_sock *inet = inet_sk(sk);

  
  	return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
  					  sk->sk_v6_daddr.s6_addr32,

  					  inet->inet_dport);

  }
  
  int inet6_hash_connect(struct inet_timewait_death_row *death_row,
  		       struct sock *sk)
  {

  	u32 port_offset = 0;
  
  	if (!inet_sk(sk)->inet_num)
  		port_offset = inet6_sk_port_offset(sk);
  	return __inet_hash_connect(death_row, sk, port_offset,

  				   __inet6_check_established);

  }

  EXPORT_SYMBOL_GPL(inet6_hash_connect);

  
  int inet6_hash(struct sock *sk)
  {

  	int err = 0;

  	if (sk->sk_state != TCP_CLOSE) {
  		local_bh_disable();

  		err = __inet_hash(sk, NULL);

  		local_bh_enable();
  	}

  	return err;

  }
  EXPORT_SYMBOL_GPL(inet6_hash);