/*
 * 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 sock *sk)
{
        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;

        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);
                spin_unlock(lock);
        }

        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
}
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_size - 1);
        struct inet_ehash_bucket *head = &hashinfo->ehash[slot];


        rcu_read_lock();
begin:
        sk_nulls_for_each_rcu(sk, node, &head->chain) {
                /* For IPV6 do the cheaper port and family tests first. */
                if (INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
                                goto begintw;
                        if (!INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                                sock_put(sk);
                                goto begin;
                        }
                goto out;
                }
        }
        if (get_nulls_value(node) != slot)
                goto begin;

begintw:
        /* Must check for a TIME_WAIT'er before going to listener hash. */
        sk_nulls_for_each_rcu(sk, node, &head->twchain) {
                if (INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
                                sk = NULL;
                                goto out;
                        }
                        if (!INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                                sock_put(sk);
                                goto begintw;
                        }
                        goto out;
                }
        }
        if (get_nulls_value(node) != slot)
                goto begintw;
        sk = NULL;
out:
        rcu_read_unlock();
        return sk;
}
EXPORT_SYMBOL(__inet6_lookup_established);

static int inline 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)->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))
                                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 *daddr,
                const unsigned short hnum, const int dif)
{
        struct sock *sk;
        const struct hlist_nulls_node *node;
        struct sock *result;
        int score, hiscore;
        unsigned int hash = inet_lhashfn(net, hnum);
        struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];

        rcu_read_lock();
begin:
        result = NULL;
        hiscore = -1;
        sk_nulls_for_each(sk, node, &ilb->head) {
                score = compute_score(sk, net, hnum, daddr, dif);
                if (score > hiscore) {
                        hiscore = score;
                        result = sk;
                }
        }
        /*
         * 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 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);
        struct net *net = sock_net(sk);
        const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
                                                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;

        spin_lock(lock);

        /* Check TIME-WAIT sockets first. */
        sk_nulls_for_each(sk2, node, &head->twchain) {
                tw = inet_twsk(sk2);

                if (INET6_TW_MATCH(sk2, net, hash, saddr, daddr, ports, dif)) {
                        if (twsk_unique(sk, sk2, twp))
                                goto unique;
                        else
                                goto not_unique;
                }
        }
        tw = NULL;

        /* And established part... */
        sk_nulls_for_each(sk2, node, &head->chain) {
                if (INET6_MATCH(sk2, net, 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);
        WARN_ON(!sk_unhashed(sk));
        __sk_nulls_add_node_rcu(sk, &head->chain);
        sk->sk_hash = hash;
        spin_unlock(lock);
        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

        if (twp != NULL) {
                *twp = tw;
                NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
        } else if (tw != NULL) {
                /* Silly. Should hash-dance instead... */
                inet_twsk_deschedule(tw, death_row);
                NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);

                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);
        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)
{
        return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
                        __inet6_check_established, __inet6_hash);
}

EXPORT_SYMBOL_GPL(inet6_hash_connect);