/*
   * 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/ip.h>

  void __inet6_hash(struct inet_hashinfo *hashinfo,
  				struct sock *sk)
  {
  	struct hlist_head *list;
  	rwlock_t *lock;
  
  	BUG_TRAP(sk_unhashed(sk));
  
  	if (sk->sk_state == TCP_LISTEN) {
  		list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
  		lock = &hashinfo->lhash_lock;
  		inet_listen_wlock(hashinfo);
  	} else {
  		unsigned int hash;
  		sk->sk_hash = hash = inet6_sk_ehashfn(sk);
  		hash &= (hashinfo->ehash_size - 1);
  		list = &hashinfo->ehash[hash].chain;
  		lock = &hashinfo->ehash[hash].lock;
  		write_lock(lock);
  	}
  
  	__sk_add_node(sk, list);
  	sock_prot_inc_use(sk->sk_prot);
  	write_unlock(lock);
  }
  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 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_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(daddr, hnum, saddr, sport);
  	struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
  
  	prefetch(head->chain.first);
  	read_lock(&head->lock);
  	sk_for_each(sk, node, &head->chain) {
  		/* For IPV6 do the cheaper port and family tests first. */
  		if (INET6_MATCH(sk, hash, saddr, daddr, ports, dif))
  			goto hit; /* You sunk my battleship! */
  	}
  	/* Must check for a TIME_WAIT'er before going to listener hash. */

  	sk_for_each(sk, node, &head->twchain) {

  		const struct inet_timewait_sock *tw = inet_twsk(sk);

  		if(*((__portpair *)&(tw->tw_dport))	== ports	&&

  		   sk->sk_family		== PF_INET6) {
  			const struct inet6_timewait_sock *tw6 = inet6_twsk(sk);
  
  			if (ipv6_addr_equal(&tw6->tw_v6_daddr, saddr)	&&
  			    ipv6_addr_equal(&tw6->tw_v6_rcv_saddr, daddr)	&&
  			    (!sk->sk_bound_dev_if || sk->sk_bound_dev_if == dif))
  				goto hit;
  		}
  	}
  	read_unlock(&head->lock);
  	return NULL;
  
  hit:
  	sock_hold(sk);
  	read_unlock(&head->lock);
  	return sk;
  }
  EXPORT_SYMBOL(__inet6_lookup_established);

  struct sock *inet6_lookup_listener(struct inet_hashinfo *hashinfo,
  				   const struct in6_addr *daddr,
  				   const unsigned short hnum, const int dif)
  {
  	struct sock *sk;
  	const struct hlist_node *node;
  	struct sock *result = NULL;
  	int score, hiscore = 0;
  
  	read_lock(&hashinfo->lhash_lock);
  	sk_for_each(sk, node, &hashinfo->listening_hash[inet_lhashfn(hnum)]) {
  		if (inet_sk(sk)->num == hnum && sk->sk_family == PF_INET6) {
  			const struct ipv6_pinfo *np = inet6_sk(sk);

  			score = 1;
  			if (!ipv6_addr_any(&np->rcv_saddr)) {
  				if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
  					continue;
  				score++;
  			}
  			if (sk->sk_bound_dev_if) {
  				if (sk->sk_bound_dev_if != dif)
  					continue;
  				score++;
  			}
  			if (score == 3) {
  				result = sk;
  				break;
  			}
  			if (score > hiscore) {
  				hiscore = score;
  				result = sk;
  			}
  		}
  	}
  	if (result)
  		sock_hold(result);
  	read_unlock(&hashinfo->lhash_lock);
  	return result;
  }
  
  EXPORT_SYMBOL_GPL(inet6_lookup_listener);
  
  struct sock *inet6_lookup(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(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 ipv6_pinfo *np = inet6_sk(sk);
  	const struct in6_addr *daddr = &np->rcv_saddr;
  	const struct in6_addr *saddr = &np->daddr;
  	const int dif = sk->sk_bound_dev_if;

  	const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);

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

  						inet->dport);
  	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
  	struct sock *sk2;
  	const struct hlist_node *node;
  	struct inet_timewait_sock *tw;
  
  	prefetch(head->chain.first);
  	write_lock(&head->lock);
  
  	/* Check TIME-WAIT sockets first. */

  	sk_for_each(sk2, node, &head->twchain) {

  		const struct inet6_timewait_sock *tw6 = inet6_twsk(sk2);
  
  		tw = inet_twsk(sk2);

  		if(*((__portpair *)&(tw->tw_dport)) == ports		 &&

  		   sk2->sk_family	       == PF_INET6	 &&
  		   ipv6_addr_equal(&tw6->tw_v6_daddr, saddr)	 &&
  		   ipv6_addr_equal(&tw6->tw_v6_rcv_saddr, daddr) &&
  		   sk2->sk_bound_dev_if == sk->sk_bound_dev_if) {
  			if (twsk_unique(sk, sk2, twp))
  				goto unique;
  			else
  				goto not_unique;
  		}
  	}
  	tw = NULL;
  
  	/* And established part... */
  	sk_for_each(sk2, node, &head->chain) {
  		if (INET6_MATCH(sk2, hash, saddr, daddr, ports, dif))
  			goto not_unique;
  	}
  
  unique:

  	/* Must record num and sport now. Otherwise we will see
  	 * in hash table socket with a funny identity. */
  	inet->num = lport;
  	inet->sport = htons(lport);

  	BUG_TRAP(sk_unhashed(sk));
  	__sk_add_node(sk, &head->chain);
  	sk->sk_hash = hash;
  	sock_prot_inc_use(sk->sk_prot);
  	write_unlock(&head->lock);
  
  	if (twp != NULL) {
  		*twp = tw;
  		NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
  	} else if (tw != NULL) {
  		/* Silly. Should hash-dance instead... */
  		inet_twsk_deschedule(tw, death_row);
  		NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
  
  		inet_twsk_put(tw);
  	}
  	return 0;
  
  not_unique:
  	write_unlock(&head->lock);
  	return -EADDRNOTAVAIL;
  }
  
  static inline u32 inet6_sk_port_offset(const struct sock *sk)
  {
  	const struct inet_sock *inet = inet_sk(sk);
  	const struct ipv6_pinfo *np = inet6_sk(sk);
  	return secure_ipv6_port_ephemeral(np->rcv_saddr.s6_addr32,
  					  np->daddr.s6_addr32,
  					  inet->dport);
  }
  
  int inet6_hash_connect(struct inet_timewait_death_row *death_row,
  		       struct sock *sk)
  {
  	struct inet_hashinfo *hinfo = death_row->hashinfo;
  	const unsigned short snum = inet_sk(sk)->num;

  	struct inet_bind_hashbucket *head;
  	struct inet_bind_bucket *tb;

  	int ret;

  	if (snum == 0) {
  		const int low = sysctl_local_port_range[0];
  		const int high = sysctl_local_port_range[1];

  		const int range = high - low;

  		int i, port;

  		static u32 hint;
  		const u32 offset = hint + inet6_sk_port_offset(sk);
  		struct hlist_node *node;

  		struct inet_timewait_sock *tw = NULL;

  		local_bh_disable();

  		for (i = 1; i <= range; i++) {
  			port = low + (i + offset) % range;

  			head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
  			spin_lock(&head->lock);

  			/* Does not bother with rcv_saddr checks,
  			 * because the established check is already
  			 * unique enough.
  			 */

  			inet_bind_bucket_for_each(tb, node, &head->chain) {

  				if (tb->port == port) {
  					BUG_TRAP(!hlist_empty(&tb->owners));
  					if (tb->fastreuse >= 0)
  						goto next_port;
  					if (!__inet6_check_established(death_row,

  								       sk, port,
  								       &tw))

  						goto ok;
  					goto next_port;
  				}
  			}

  			tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,

  						     head, port);

  			if (!tb) {
  				spin_unlock(&head->lock);
  				break;
  			}
  			tb->fastreuse = -1;
  			goto ok;

  		next_port:
  			spin_unlock(&head->lock);
  		}
  		local_bh_enable();

  		return -EADDRNOTAVAIL;

  
  ok:
  		hint += i;

  		/* Head lock still held and bh's disabled */
  		inet_bind_hash(sk, tb, port);

  		if (sk_unhashed(sk)) {

  			inet_sk(sk)->sport = htons(port);
  			__inet6_hash(hinfo, sk);
  		}
  		spin_unlock(&head->lock);

  		if (tw) {
  			inet_twsk_deschedule(tw, death_row);
  			inet_twsk_put(tw);
  		}

  
  		ret = 0;
  		goto out;

  	}

  	head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
  	tb   = inet_csk(sk)->icsk_bind_hash;

  	spin_lock_bh(&head->lock);
  
  	if (sk_head(&tb->owners) == sk && sk->sk_bind_node.next == NULL) {
  		__inet6_hash(hinfo, sk);
  		spin_unlock_bh(&head->lock);
  		return 0;
  	} else {
  		spin_unlock(&head->lock);
  		/* No definite answer... Walk to established hash table */
  		ret = __inet6_check_established(death_row, sk, snum, NULL);
  out:
  		local_bh_enable();
  		return ret;
  	}
  }
  
  EXPORT_SYMBOL_GPL(inet6_hash_connect);