/*
   * 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
   *
   *	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.
   */
  
  #ifndef _INET_HASHTABLES_H
  #define _INET_HASHTABLES_H
  
  
  #include <linux/interrupt.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <linux/list.h>
  #include <linux/slab.h>
  #include <linux/socket.h>
  #include <linux/spinlock.h>
  #include <linux/types.h>
  #include <linux/wait.h>
  #include <linux/vmalloc.h>
  
  #include <net/inet_connection_sock.h>
  #include <net/inet_sock.h>
  #include <net/sock.h>
  #include <net/route.h>
  #include <net/tcp_states.h>
  #include <net/netns/hash.h>
  
  #include <linux/atomic.h>
  #include <asm/byteorder.h>
  
  /* This is for all connections with a full identity, no wildcards.
   * The 'e' prefix stands for Establish, but we really put all sockets
   * but LISTEN ones.
   */
  struct inet_ehash_bucket {
  	struct hlist_nulls_head chain;
  };
  
  /* There are a few simple rules, which allow for local port reuse by
   * an application.  In essence:
   *
   *	1) Sockets bound to different interfaces may share a local port.
   *	   Failing that, goto test 2.
   *	2) If all sockets have sk->sk_reuse set, and none of them are in
   *	   TCP_LISTEN state, the port may be shared.
   *	   Failing that, goto test 3.
   *	3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
   *	   address, and none of them are the same, the port may be
   *	   shared.
   *	   Failing this, the port cannot be shared.
   *
   * The interesting point, is test #2.  This is what an FTP server does
   * all day.  To optimize this case we use a specific flag bit defined
   * below.  As we add sockets to a bind bucket list, we perform a
   * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
   * As long as all sockets added to a bind bucket pass this test,
   * the flag bit will be set.
   * The resulting situation is that tcp_v[46]_verify_bind() can just check
   * for this flag bit, if it is set and the socket trying to bind has
   * sk->sk_reuse set, we don't even have to walk the owners list at all,
   * we return that it is ok to bind this socket to the requested local port.
   *
   * Sounds like a lot of work, but it is worth it.  In a more naive
   * implementation (ie. current FreeBSD etc.) the entire list of ports
   * must be walked for each data port opened by an ftp server.  Needless
   * to say, this does not scale at all.  With a couple thousand FTP
   * users logged onto your box, isn't it nice to know that new data
   * ports are created in O(1) time?  I thought so. ;-)	-DaveM
   */
  struct inet_bind_bucket {
  #ifdef CONFIG_NET_NS
  	struct net		*ib_net;
  #endif
  	unsigned short		port;
  	signed char		fastreuse;
  	signed char		fastreuseport;
  	kuid_t			fastuid;
  	int			num_owners;
  	struct hlist_node	node;
  	struct hlist_head	owners;
  };
  
  static inline struct net *ib_net(struct inet_bind_bucket *ib)
  {
  	return read_pnet(&ib->ib_net);
  }
  
  #define inet_bind_bucket_for_each(tb, head) \
  	hlist_for_each_entry(tb, head, node)
  
  struct inet_bind_hashbucket {
  	spinlock_t		lock;
  	struct hlist_head	chain;
  };
  
  /*
   * Sockets can be hashed in established or listening table
   * We must use different 'nulls' end-of-chain value for listening
   * hash table, or we might find a socket that was closed and
   * reallocated/inserted into established hash table
   */
  #define LISTENING_NULLS_BASE (1U << 29)
  struct inet_listen_hashbucket {
  	spinlock_t		lock;
  	struct hlist_nulls_head	head;
  };
  
  /* This is for listening sockets, thus all sockets which possess wildcards. */
  #define INET_LHTABLE_SIZE	32	/* Yes, really, this is all you need. */
  
  struct inet_hashinfo {
  	/* This is for sockets with full identity only.  Sockets here will
  	 * always be without wildcards and will have the following invariant:
  	 *
  	 *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
  	 *
  	 */
  	struct inet_ehash_bucket	*ehash;
  	spinlock_t			*ehash_locks;
  	unsigned int			ehash_mask;
  	unsigned int			ehash_locks_mask;
  
  	/* Ok, let's try this, I give up, we do need a local binding
  	 * TCP hash as well as the others for fast bind/connect.
  	 */
  	struct inet_bind_hashbucket	*bhash;
  
  	unsigned int			bhash_size;
  	/* 4 bytes hole on 64 bit */
  
  	struct kmem_cache		*bind_bucket_cachep;
  
  	/* All the above members are written once at bootup and
  	 * never written again _or_ are predominantly read-access.
  	 *
  	 * Now align to a new cache line as all the following members
  	 * might be often dirty.
  	 */
  	/* All sockets in TCP_LISTEN state will be in here.  This is the only
  	 * table where wildcard'd TCP sockets can exist.  Hash function here
  	 * is just local port number.
  	 */
  	struct inet_listen_hashbucket	listening_hash[INET_LHTABLE_SIZE]
  					____cacheline_aligned_in_smp;
  
  	atomic_t			bsockets;
  };
  
  static inline struct inet_ehash_bucket *inet_ehash_bucket(
  	struct inet_hashinfo *hashinfo,
  	unsigned int hash)
  {
  	return &hashinfo->ehash[hash & hashinfo->ehash_mask];
  }
  
  static inline spinlock_t *inet_ehash_lockp(
  	struct inet_hashinfo *hashinfo,
  	unsigned int hash)
  {
  	return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
  }
  
  static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
  {
  	unsigned int i, size = 256;
  #if defined(CONFIG_PROVE_LOCKING)
  	unsigned int nr_pcpus = 2;
  #else
  	unsigned int nr_pcpus = num_possible_cpus();
  #endif
  	if (nr_pcpus >= 4)
  		size = 512;
  	if (nr_pcpus >= 8)
  		size = 1024;
  	if (nr_pcpus >= 16)
  		size = 2048;
  	if (nr_pcpus >= 32)
  		size = 4096;
  	if (sizeof(spinlock_t) != 0) {
  #ifdef CONFIG_NUMA
  		if (size * sizeof(spinlock_t) > PAGE_SIZE)
  			hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t));
  		else
  #endif
  		hashinfo->ehash_locks =	kmalloc(size * sizeof(spinlock_t),
  						GFP_KERNEL);
  		if (!hashinfo->ehash_locks)
  			return ENOMEM;
  		for (i = 0; i < size; i++)
  			spin_lock_init(&hashinfo->ehash_locks[i]);
  	}
  	hashinfo->ehash_locks_mask = size - 1;
  	return 0;
  }
  
  static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
  {
  	if (hashinfo->ehash_locks) {
  #ifdef CONFIG_NUMA
  		unsigned int size = (hashinfo->ehash_locks_mask + 1) *
  							sizeof(spinlock_t);
  		if (size > PAGE_SIZE)
  			vfree(hashinfo->ehash_locks);
  		else
  #endif
  		kfree(hashinfo->ehash_locks);
  		hashinfo->ehash_locks = NULL;
  	}
  }
  
  struct inet_bind_bucket *
  inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
  			struct inet_bind_hashbucket *head,
  			const unsigned short snum);
  void inet_bind_bucket_destroy(struct kmem_cache *cachep,
  			      struct inet_bind_bucket *tb);
  
  static inline int inet_bhashfn(struct net *net, const __u16 lport,
  			       const int bhash_size)
  {
  	return (lport + net_hash_mix(net)) & (bhash_size - 1);
  }
  
  void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
  		    const unsigned short snum);
  
  /* These can have wildcards, don't try too hard. */
  static inline int inet_lhashfn(struct net *net, const unsigned short num)
  {
  	return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
  }
  
  static inline int inet_sk_listen_hashfn(const struct sock *sk)
  {
  	return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
  }
  
  /* Caller must disable local BH processing. */
  int __inet_inherit_port(struct sock *sk, struct sock *child);
  
  void inet_put_port(struct sock *sk);
  
  void inet_hashinfo_init(struct inet_hashinfo *h);
  
  int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw);
  void inet_hash(struct sock *sk);
  void inet_unhash(struct sock *sk);
  
  struct sock *__inet_lookup_listener(struct net *net,
  				    struct inet_hashinfo *hashinfo,
  				    const __be32 saddr, const __be16 sport,
  				    const __be32 daddr,
  				    const unsigned short hnum,
  				    const int dif);
  
  static inline struct sock *inet_lookup_listener(struct net *net,
  		struct inet_hashinfo *hashinfo,
  		__be32 saddr, __be16 sport,
  		__be32 daddr, __be16 dport, int dif)
  {
  	return __inet_lookup_listener(net, hashinfo, saddr, sport,
  				      daddr, ntohs(dport), dif);
  }
  
  /* Socket demux engine toys. */
  /* What happens here is ugly; there's a pair of adjacent fields in
     struct inet_sock; __be16 dport followed by __u16 num.  We want to
     search by pair, so we combine the keys into a single 32bit value
     and compare with 32bit value read from &...->dport.  Let's at least
     make sure that it's not mixed with anything else...
     On 64bit targets we combine comparisons with pair of adjacent __be32
     fields in the same way.
  */
  #ifdef __BIG_ENDIAN
  #define INET_COMBINED_PORTS(__sport, __dport) \
  	((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
  #else /* __LITTLE_ENDIAN */
  #define INET_COMBINED_PORTS(__sport, __dport) \
  	((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
  #endif
  
  #if (BITS_PER_LONG == 64)
  #ifdef __BIG_ENDIAN
  #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
  	const __addrpair __name = (__force __addrpair) ( \
  				   (((__force __u64)(__be32)(__saddr)) << 32) | \
  				   ((__force __u64)(__be32)(__daddr)));
  #else /* __LITTLE_ENDIAN */
  #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
  	const __addrpair __name = (__force __addrpair) ( \
  				   (((__force __u64)(__be32)(__daddr)) << 32) | \
  				   ((__force __u64)(__be32)(__saddr)));
  #endif /* __BIG_ENDIAN */
  #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif)	\
  	(((__sk)->sk_portpair == (__ports))			&&	\
  	 ((__sk)->sk_addrpair == (__cookie))			&&	\
  	 (!(__sk)->sk_bound_dev_if	||				\
  	   ((__sk)->sk_bound_dev_if == (__dif))) 		&& 	\
  	 net_eq(sock_net(__sk), (__net)))
  #else /* 32-bit arch */
  #define INET_ADDR_COOKIE(__name, __saddr, __daddr)
  #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \
  	(((__sk)->sk_portpair == (__ports))		&&		\
  	 ((__sk)->sk_daddr	== (__saddr))		&&		\
  	 ((__sk)->sk_rcv_saddr	== (__daddr))		&&		\
  	 (!(__sk)->sk_bound_dev_if	||				\
  	   ((__sk)->sk_bound_dev_if == (__dif))) 	&&		\
  	 net_eq(sock_net(__sk), (__net)))
  #endif /* 64-bit arch */
  
  /*
   * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
   * not check it for lookups anymore, thanks Alexey. -DaveM
   *
   * Local BH must be disabled here.
   */
  struct sock *__inet_lookup_established(struct net *net,
  				       struct inet_hashinfo *hashinfo,
  				       const __be32 saddr, const __be16 sport,
  				       const __be32 daddr, const u16 hnum,
  				       const int dif);
  
  static inline struct sock *
  	inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
  				const __be32 saddr, const __be16 sport,
  				const __be32 daddr, const __be16 dport,
  				const int dif)
  {
  	return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
  					 ntohs(dport), dif);
  }
  
  static inline struct sock *__inet_lookup(struct net *net,
  					 struct inet_hashinfo *hashinfo,
  					 const __be32 saddr, const __be16 sport,
  					 const __be32 daddr, const __be16 dport,
  					 const int dif)
  {
  	u16 hnum = ntohs(dport);
  	struct sock *sk = __inet_lookup_established(net, hashinfo,
  				saddr, sport, daddr, hnum, dif);
  
  	return sk ? : __inet_lookup_listener(net, hashinfo, saddr, sport,
  					     daddr, hnum, dif);
  }
  
  static inline struct sock *inet_lookup(struct net *net,
  				       struct inet_hashinfo *hashinfo,
  				       const __be32 saddr, const __be16 sport,
  				       const __be32 daddr, const __be16 dport,
  				       const int dif)
  {
  	struct sock *sk;
  
  	local_bh_disable();
  	sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif);
  	local_bh_enable();
  
  	return sk;
  }
  
  static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
  					     struct sk_buff *skb,
  					     const __be16 sport,
  					     const __be16 dport)
  {
  	struct sock *sk = skb_steal_sock(skb);
  	const struct iphdr *iph = ip_hdr(skb);
  
  	if (sk)
  		return sk;
  	else
  		return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
  				     iph->saddr, sport,
  				     iph->daddr, dport, inet_iif(skb));
  }
  
  int __inet_hash_connect(struct inet_timewait_death_row *death_row,
  			struct sock *sk, u32 port_offset,
  			int (*check_established)(struct inet_timewait_death_row *,
  						 struct sock *, __u16,
  						 struct inet_timewait_sock **),
  			int (*hash)(struct sock *sk,
  				    struct inet_timewait_sock *twp));
  
  int inet_hash_connect(struct inet_timewait_death_row *death_row,
  		      struct sock *sk);
  #endif /* _INET_HASHTABLES_H */