/*
 * 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/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/tcp_states.h>
#include <net/netns/hash.h>

#include <asm/atomic.h>
#include <asm/byteorder.h>

/* This is for all connections with a full identity, no wildcards.
 * One chain is dedicated to TIME_WAIT sockets.
 * I'll experiment with dynamic table growth later.
 */
struct inet_ehash_bucket {
        struct hlist_head chain;
        struct hlist_head twchain;
};

/* 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 {
        struct net              *ib_net;
        unsigned short          port;
        signed short            fastreuse;
        struct hlist_node       node;
        struct hlist_head       owners;
};

#define inet_bind_bucket_for_each(tb, node, head) \
        hlist_for_each_entry(tb, node, head, node)

struct inet_bind_hashbucket {
        spinlock_t              lock;
        struct hlist_head       chain;
};

/* 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
         *
         * TIME_WAIT sockets use a separate chain (twchain).
         */
        struct inet_ehash_bucket        *ehash;
        rwlock_t                        *ehash_locks;
        unsigned int                    ehash_size;
        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;
        /* Note : 4 bytes padding on 64 bit arches */

        /* 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 hlist_head               listening_hash[INET_LHTABLE_SIZE];

        /* 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
         * are often dirty.
         */
        rwlock_t                        lhash_lock ____cacheline_aligned;
        atomic_t                        lhash_users;
        wait_queue_head_t               lhash_wait;
        struct kmem_cache                       *bind_bucket_cachep;
};

static inline struct inet_ehash_bucket *inet_ehash_bucket(
        struct inet_hashinfo *hashinfo,
        unsigned int hash)
{
        return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)];
}

static inline rwlock_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(rwlock_t) != 0) {
#ifdef CONFIG_NUMA
                if (size * sizeof(rwlock_t) > PAGE_SIZE)
                        hashinfo->ehash_locks = vmalloc(size * sizeof(rwlock_t));
                else
#endif
                hashinfo->ehash_locks = kmalloc(size * sizeof(rwlock_t),
                                                GFP_KERNEL);
                if (!hashinfo->ehash_locks)
                        return ENOMEM;
                for (i = 0; i < size; i++)
                        rwlock_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(rwlock_t);
                if (size > PAGE_SIZE)
                        vfree(hashinfo->ehash_locks);
                else
#endif
                kfree(hashinfo->ehash_locks);
                hashinfo->ehash_locks = NULL;
        }
}

extern struct inet_bind_bucket *
                    inet_bind_bucket_create(struct kmem_cache *cachep,
                                            struct net *net,
                                            struct inet_bind_hashbucket *head,
                                            const unsigned short snum);
extern 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);
}

extern 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)->num);
}

/* Caller must disable local BH processing. */
extern void __inet_inherit_port(struct sock *sk, struct sock *child);

extern void inet_put_port(struct sock *sk);

extern void inet_listen_wlock(struct inet_hashinfo *hashinfo);

/*
 * - We may sleep inside this lock.
 * - If sleeping is not required (or called from BH),
 *   use plain read_(un)lock(&inet_hashinfo.lhash_lock).
 */
static inline void inet_listen_lock(struct inet_hashinfo *hashinfo)
{
        /* read_lock synchronizes to candidates to writers */
        read_lock(&hashinfo->lhash_lock);
        atomic_inc(&hashinfo->lhash_users);
        read_unlock(&hashinfo->lhash_lock);
}

static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo)
{
        if (atomic_dec_and_test(&hashinfo->lhash_users))
                wake_up(&hashinfo->lhash_wait);
}

extern void __inet_hash_nolisten(struct sock *sk);
extern void inet_hash(struct sock *sk);
extern void inet_unhash(struct sock *sk);

extern struct sock *__inet_lookup_listener(struct net *net,
                                           struct inet_hashinfo *hashinfo,
                                           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 daddr, __be16 dport, int dif)
{
        return __inet_lookup_listener(net, hashinfo, 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.
*/
typedef __u32 __bitwise __portpair;
#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)
typedef __u64 __bitwise __addrpair;
#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, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
        (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net)   &&      \
         ((*((__addrpair *)&(inet_sk(__sk)->daddr))) == (__cookie))     &&      \
         ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports))      &&      \
         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
#define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
        (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net)   &&      \
         ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) &&     \
         ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&      \
         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
#else /* 32-bit arch */
#define INET_ADDR_COOKIE(__name, __saddr, __daddr)
#define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)     \
        (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net)   &&      \
         (inet_sk(__sk)->daddr          == (__saddr))           &&      \
         (inet_sk(__sk)->rcv_saddr      == (__daddr))           &&      \
         ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports))      &&      \
         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
#define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif)   \
        (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net)   &&      \
         (inet_twsk(__sk)->tw_daddr     == (__saddr))           &&      \
         (inet_twsk(__sk)->tw_rcv_saddr == (__daddr))           &&      \
         ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&      \
         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
#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.
 */
extern 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, 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;
}

extern 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 **),
                               void (*hash)(struct sock *sk));
extern int inet_hash_connect(struct inet_timewait_death_row *death_row,
                             struct sock *sk);
#endif /* _INET_HASHTABLES_H */