Subversion Repositories test_project

/*

 * 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 INET transport hashtables

 *

 * 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.

 */

#include <linux/module.h>

#include <linux/random.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/wait.h>

#include <net/inet_connection_sock.h>

#include <net/inet_hashtables.h>

#include <net/ip.h>

/*

 * Allocate and initialize a new local port bind bucket.

 * The bindhash mutex for snum's hash chain must be held here.

 */

struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,

                                                 struct inet_bind_hashbucket *head,

                                                 const unsigned short snum)

{

        struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);

        if (tb != NULL) {

                tb->port      = snum;

                tb->fastreuse = 0;

                INIT_HLIST_HEAD(&tb->owners);

                hlist_add_head(&tb->node, &head->chain);

        }

        return tb;

}

/*

 * Caller must hold hashbucket lock for this tb with local BH disabled

 */

void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)

{

        if (hlist_empty(&tb->owners)) {

                __hlist_del(&tb->node);

                kmem_cache_free(cachep, tb);

        }

}

void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,

                    const unsigned short snum)

{

        inet_sk(sk)->num = snum;

        sk_add_bind_node(sk, &tb->owners);

        inet_csk(sk)->icsk_bind_hash = tb;

}

/*

 * Get rid of any references to a local port held by the given sock.

 */

static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)

{

        const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);

        struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];

        struct inet_bind_bucket *tb;

        spin_lock(&head->lock);

        tb = inet_csk(sk)->icsk_bind_hash;

        __sk_del_bind_node(sk);

        inet_csk(sk)->icsk_bind_hash = NULL;

        inet_sk(sk)->num = 0;

        inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);

        spin_unlock(&head->lock);

}

void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)

{

        local_bh_disable();

        __inet_put_port(hashinfo, sk);

        local_bh_enable();

}

EXPORT_SYMBOL(inet_put_port);

/*

 * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.

 * Look, when several writers sleep and reader wakes them up, all but one

 * immediately hit write lock and grab all the cpus. Exclusive sleep solves

 * this, _but_ remember, it adds useless work on UP machines (wake up each

 * exclusive lock release). It should be ifdefed really.

 */

void inet_listen_wlock(struct inet_hashinfo *hashinfo)

{

        write_lock(&hashinfo->lhash_lock);

        if (atomic_read(&hashinfo->lhash_users)) {

                DEFINE_WAIT(wait);

                for (;;) {

                        prepare_to_wait_exclusive(&hashinfo->lhash_wait,

                                                  &wait, TASK_UNINTERRUPTIBLE);

                        if (!atomic_read(&hashinfo->lhash_users))

                                break;

                        write_unlock_bh(&hashinfo->lhash_lock);

                        schedule();

                        write_lock_bh(&hashinfo->lhash_lock);

                }

                finish_wait(&hashinfo->lhash_wait, &wait);

        }

}

EXPORT_SYMBOL(inet_listen_wlock);

/*

 * Don't inline this cruft. Here are some nice properties to exploit here. The

 * BSD API does not allow a listening sock to specify the remote port nor the

 * remote address for the connection. So always assume those are both

 * wildcarded during the search since they can never be otherwise.

 */

static struct sock *inet_lookup_listener_slow(const struct hlist_head *head,

                                              const __be32 daddr,

                                              const unsigned short hnum,

                                              const int dif)

{

        struct sock *result = NULL, *sk;

        const struct hlist_node *node;

        int hiscore = -1;

        sk_for_each(sk, node, head) {

                const struct inet_sock *inet = inet_sk(sk);

                if (inet->num == hnum && !ipv6_only_sock(sk)) {

                        const __be32 rcv_saddr = inet->rcv_saddr;

                        int score = sk->sk_family == PF_INET ? 1 : 0;

                        if (rcv_saddr) {

                                if (rcv_saddr != daddr)

                                        continue;

                                score += 2;

                        }

                        if (sk->sk_bound_dev_if) {

                                if (sk->sk_bound_dev_if != dif)

                                        continue;

                                score += 2;

                        }

                        if (score == 5)

                                return sk;

                        if (score > hiscore) {

                                hiscore = score;

                                result  = sk;

                        }

                }

        }

        return result;

}

/* Optimize the common listener case. */

struct sock *__inet_lookup_listener(struct inet_hashinfo *hashinfo,

                                    const __be32 daddr, const unsigned short hnum,

                                    const int dif)

{

        struct sock *sk = NULL;

        const struct hlist_head *head;

        read_lock(&hashinfo->lhash_lock);

        head = &hashinfo->listening_hash[inet_lhashfn(hnum)];

        if (!hlist_empty(head)) {

                const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));

                if (inet->num == hnum && !sk->sk_node.next &&

                    (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&

                    (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&

                    !sk->sk_bound_dev_if)

                        goto sherry_cache;

                sk = inet_lookup_listener_slow(head, daddr, hnum, dif);

        }

        if (sk) {

sherry_cache:

                sock_hold(sk);

        }

        read_unlock(&hashinfo->lhash_lock);

        return sk;

}

EXPORT_SYMBOL_GPL(__inet_lookup_listener);

/* called with local bh disabled */

static int __inet_check_established(struct inet_timewait_death_row *death_row,

                                    struct sock *sk, __u16 lport,

                                    struct inet_timewait_sock **twp)

{

        struct inet_hashinfo *hinfo = death_row->hashinfo;

        struct inet_sock *inet = inet_sk(sk);

        __be32 daddr = inet->rcv_saddr;

        __be32 saddr = inet->daddr;

        int dif = sk->sk_bound_dev_if;

        INET_ADDR_COOKIE(acookie, saddr, daddr)

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

        unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);

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

        rwlock_t *lock = inet_ehash_lockp(hinfo, hash);

        struct sock *sk2;

        const struct hlist_node *node;

        struct inet_timewait_sock *tw;

        prefetch(head->chain.first);

        write_lock(lock);

        /* Check TIME-WAIT sockets first. */

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

                tw = inet_twsk(sk2);

                if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {

                        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 (INET_MATCH(sk2, hash, acookie, 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);

        sk->sk_hash = hash;

        BUG_TRAP(sk_unhashed(sk));

        __sk_add_node(sk, &head->chain);

        sock_prot_inc_use(sk->sk_prot);

        write_unlock(lock);

        if (twp) {

                *twp = tw;

                NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);

        } else if (tw) {

                /* 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(lock);

        return -EADDRNOTAVAIL;

}

static inline u32 inet_sk_port_offset(const struct sock *sk)

{

        const struct inet_sock *inet = inet_sk(sk);

        return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,

                                          inet->dport);

}

/*

 * Bind a port for a connect operation and hash it.

 */

int inet_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) {

                int i, remaining, low, high, port;

                static u32 hint;

                u32 offset = hint + inet_sk_port_offset(sk);

                struct hlist_node *node;

                struct inet_timewait_sock *tw = NULL;

                inet_get_local_port_range(&low, &high);

                remaining = (high - low) + 1;

                local_bh_disable();

                for (i = 1; i <= remaining; i++) {

                        port = low + (i + offset) % remaining;

                        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 (!__inet_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);

                        __inet_hash(hinfo, sk, 0);

                }

                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) {

                __inet_hash(hinfo, sk, 0);

                spin_unlock_bh(&head->lock);

                return 0;

        } else {

                spin_unlock(&head->lock);

                /* No definite answer... Walk to established hash table */

                ret = __inet_check_established(death_row, sk, snum, NULL);

out:

                local_bh_enable();

                return ret;

        }

}

EXPORT_SYMBOL_GPL(inet_hash_connect);