/*
   * 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/inet_connection_sock.h>
  #include <net/inet_hashtables.h>
  #include <net/inet6_hashtables.h>
  #include <net/secure_seq.h>
  #include <net/ip.h>
  
  static unsigned int inet6_ehashfn(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));
  }
  
  static int inet6_sk_ehashfn(const struct sock *sk)
  {
  	const struct inet_sock *inet = inet_sk(sk);
  	const struct in6_addr *laddr = &sk->sk_v6_rcv_saddr;
  	const struct in6_addr *faddr = &sk->sk_v6_daddr;
  	const __u16 lport = inet->inet_num;
  	const __be16 fport = inet->inet_dport;
  	struct net *net = sock_net(sk);
  
  	return inet6_ehashfn(net, laddr, lport, faddr, fport);
  }
  
  int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw)
  {
  	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
  	int twrefcnt = 0;
  
  	WARN_ON(!sk_unhashed(sk));
  
  	if (sk->sk_state == TCP_LISTEN) {
  		struct inet_listen_hashbucket *ilb;
  
  		ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
  		spin_lock(&ilb->lock);
  		__sk_nulls_add_node_rcu(sk, &ilb->head);
  		spin_unlock(&ilb->lock);
  	} else {
  		unsigned int hash;
  		struct hlist_nulls_head *list;
  		spinlock_t *lock;
  
  		sk->sk_hash = hash = inet6_sk_ehashfn(sk);
  		list = &inet_ehash_bucket(hashinfo, hash)->chain;
  		lock = inet_ehash_lockp(hashinfo, hash);
  		spin_lock(lock);
  		__sk_nulls_add_node_rcu(sk, list);
  		if (tw) {
  			WARN_ON(sk->sk_hash != tw->tw_hash);
  			twrefcnt = inet_twsk_unhash(tw);
  		}
  		spin_unlock(lock);
  	}
  
  	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
  	return twrefcnt;
  }
  EXPORT_SYMBOL(__inet6_hash);
  
  /*
   * 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)
  {
  	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];
  
  
  	rcu_read_lock();
  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))
  			continue;
  		if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
  			goto out;
  
  		if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif))) {
  			sock_gen_put(sk);
  			goto begin;
  		}
  		goto found;
  	}
  	if (get_nulls_value(node) != slot)
  		goto begin;
  out:
  	sk = NULL;
  found:
  	rcu_read_unlock();
  	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)
  {
  	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) {
  			if (sk->sk_bound_dev_if != dif)
  				return -1;
  			score++;
  		}
  	}
  	return score;
  }
  
  struct sock *inet6_lookup_listener(struct net *net,
  		struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
  		const __be16 sport, const struct in6_addr *daddr,
  		const unsigned short hnum, const int dif)
  {
  	struct sock *sk;
  	const struct hlist_nulls_node *node;
  	struct sock *result;
  	int score, hiscore, matches = 0, reuseport = 0;
  	u32 phash = 0;
  	unsigned int hash = inet_lhashfn(net, hnum);
  	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
  
  	rcu_read_lock();
  begin:
  	result = NULL;
  	hiscore = 0;
  	sk_nulls_for_each(sk, node, &ilb->head) {
  		score = compute_score(sk, net, hnum, daddr, dif);
  		if (score > hiscore) {
  			hiscore = score;
  			result = sk;
  			reuseport = sk->sk_reuseport;
  			if (reuseport) {
  				phash = inet6_ehashfn(net, daddr, hnum,
  						      saddr, sport);
  				matches = 1;
  			}
  		} else if (score == hiscore && reuseport) {
  			matches++;
  			if (((u64)phash * matches) >> 32 == 0)
  				result = sk;
  			phash = next_pseudo_random32(phash);
  		}
  	}
  	/*
  	 * if the nulls value we got at the end of this lookup is
  	 * not the expected one, we must restart lookup.
  	 * We probably met an item that was moved to another chain.
  	 */
  	if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
  		goto begin;
  	if (result) {
  		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
  			result = NULL;
  		else if (unlikely(compute_score(result, net, hnum, daddr,
  				  dif) < hiscore)) {
  			sock_put(result);
  			goto begin;
  		}
  	}
  	rcu_read_unlock();
  	return result;
  }
  
  EXPORT_SYMBOL_GPL(inet6_lookup_listener);
  
  struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
  			  const struct in6_addr *saddr, const __be16 sport,
  			  const struct in6_addr *daddr, const __be16 dport,
  			  const int dif)
  {
  	struct sock *sk;
  
  	local_bh_disable();
  	sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
  	local_bh_enable();
  
  	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;
  	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
  	struct net *net = sock_net(sk);
  	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;
  	int twrefcnt = 0;
  
  	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))) {
  			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) {
  		twrefcnt = inet_twsk_unhash(tw);
  		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
  	}
  	spin_unlock(lock);
  	if (twrefcnt)
  		inet_twsk_put(tw);
  	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(tw, death_row);
  
  		inet_twsk_put(tw);
  	}
  	return 0;
  
  not_unique:
  	spin_unlock(lock);
  	return -EADDRNOTAVAIL;
  }
  
  static inline 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)
  {
  	return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
  			__inet6_check_established, __inet6_hash);
  }
  
  EXPORT_SYMBOL_GPL(inet6_hash_connect);