[mirror_ubuntu-artful-kernel.git] / net / dccp / proto.c

/*
 *  net/dccp/proto.c
 *
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *      This program is free software; you can redistribute it and/or modify it
 *      under the terms of the GNU General Public License version 2 as
 *      published by the Free Software Foundation.
 */

#include <linux/dccp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/random.h>
#include <net/checksum.h>

#include <net/inet_sock.h>
#include <net/sock.h>
#include <net/xfrm.h>

#include <asm/ioctls.h>
#include <asm/semaphore.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/delay.h>
#include <linux/poll.h>

#include "ccid.h"
#include "dccp.h"
#include "feat.h"

DEFINE_SNMP_STAT(struct dccp_mib, dccp_statistics) __read_mostly;

EXPORT_SYMBOL_GPL(dccp_statistics);

atomic_t dccp_orphan_count = ATOMIC_INIT(0);

EXPORT_SYMBOL_GPL(dccp_orphan_count);

struct inet_hashinfo __cacheline_aligned dccp_hashinfo = {
        .lhash_lock     = RW_LOCK_UNLOCKED,
        .lhash_users    = ATOMIC_INIT(0),
        .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait),
};

EXPORT_SYMBOL_GPL(dccp_hashinfo);

/* the maximum queue length for tx in packets. 0 is no limit */
int sysctl_dccp_tx_qlen __read_mostly = 5;

void dccp_set_state(struct sock *sk, const int state)
{
        const int oldstate = sk->sk_state;

        dccp_pr_debug("%s(%p) %-10.10s -> %s\n",
                      dccp_role(sk), sk,
                      dccp_state_name(oldstate), dccp_state_name(state));
        WARN_ON(state == oldstate);

        switch (state) {
        case DCCP_OPEN:
                if (oldstate != DCCP_OPEN)
                        DCCP_INC_STATS(DCCP_MIB_CURRESTAB);
                break;

        case DCCP_CLOSED:
                if (oldstate == DCCP_CLOSING || oldstate == DCCP_OPEN)
                        DCCP_INC_STATS(DCCP_MIB_ESTABRESETS);

                sk->sk_prot->unhash(sk);
                if (inet_csk(sk)->icsk_bind_hash != NULL &&
                    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
                        inet_put_port(&dccp_hashinfo, sk);
                /* fall through */
        default:
                if (oldstate == DCCP_OPEN)
                        DCCP_DEC_STATS(DCCP_MIB_CURRESTAB);
        }

        /* Change state AFTER socket is unhashed to avoid closed
         * socket sitting in hash tables.
         */
        sk->sk_state = state;
}

EXPORT_SYMBOL_GPL(dccp_set_state);

void dccp_done(struct sock *sk)
{
        dccp_set_state(sk, DCCP_CLOSED);
        dccp_clear_xmit_timers(sk);

        sk->sk_shutdown = SHUTDOWN_MASK;

        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_state_change(sk);
        else
                inet_csk_destroy_sock(sk);
}

EXPORT_SYMBOL_GPL(dccp_done);

const char *dccp_packet_name(const int type)
{
        static const char *dccp_packet_names[] = {
                [DCCP_PKT_REQUEST]  = "REQUEST",
                [DCCP_PKT_RESPONSE] = "RESPONSE",
                [DCCP_PKT_DATA]     = "DATA",
                [DCCP_PKT_ACK]      = "ACK",
                [DCCP_PKT_DATAACK]  = "DATAACK",
                [DCCP_PKT_CLOSEREQ] = "CLOSEREQ",
                [DCCP_PKT_CLOSE]    = "CLOSE",
                [DCCP_PKT_RESET]    = "RESET",
                [DCCP_PKT_SYNC]     = "SYNC",
                [DCCP_PKT_SYNCACK]  = "SYNCACK",
        };

        if (type >= DCCP_NR_PKT_TYPES)
                return "INVALID";
        else
                return dccp_packet_names[type];
}

EXPORT_SYMBOL_GPL(dccp_packet_name);

const char *dccp_state_name(const int state)
{
        static char *dccp_state_names[] = {
        [DCCP_OPEN]       = "OPEN",
        [DCCP_REQUESTING] = "REQUESTING",
        [DCCP_PARTOPEN]   = "PARTOPEN",
        [DCCP_LISTEN]     = "LISTEN",
        [DCCP_RESPOND]    = "RESPOND",
        [DCCP_CLOSING]    = "CLOSING",
        [DCCP_TIME_WAIT]  = "TIME_WAIT",
        [DCCP_CLOSED]     = "CLOSED",
        };

        if (state >= DCCP_MAX_STATES)
                return "INVALID STATE!";
        else
                return dccp_state_names[state];
}

EXPORT_SYMBOL_GPL(dccp_state_name);

void dccp_hash(struct sock *sk)
{
        inet_hash(&dccp_hashinfo, sk);
}

EXPORT_SYMBOL_GPL(dccp_hash);

void dccp_unhash(struct sock *sk)
{
        inet_unhash(&dccp_hashinfo, sk);
}

EXPORT_SYMBOL_GPL(dccp_unhash);

int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
{
        struct dccp_sock *dp = dccp_sk(sk);
        struct dccp_minisock *dmsk = dccp_msk(sk);
        struct inet_connection_sock *icsk = inet_csk(sk);

        dccp_minisock_init(&dp->dccps_minisock);

        /*
         * FIXME: We're hardcoding the CCID, and doing this at this point makes
         * the listening (master) sock get CCID control blocks, which is not
         * necessary, but for now, to not mess with the test userspace apps,
         * lets leave it here, later the real solution is to do this in a
         * setsockopt(CCIDs-I-want/accept). -acme
         */
        if (likely(ctl_sock_initialized)) {
                int rc = dccp_feat_init(dmsk);

                if (rc)
                        return rc;

                if (dmsk->dccpms_send_ack_vector) {
                        dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(GFP_KERNEL);
                        if (dp->dccps_hc_rx_ackvec == NULL)
                                return -ENOMEM;
                }
                dp->dccps_hc_rx_ccid = ccid_hc_rx_new(dmsk->dccpms_rx_ccid,
                                                      sk, GFP_KERNEL);
                dp->dccps_hc_tx_ccid = ccid_hc_tx_new(dmsk->dccpms_tx_ccid,
                                                      sk, GFP_KERNEL);
                if (unlikely(dp->dccps_hc_rx_ccid == NULL ||
                             dp->dccps_hc_tx_ccid == NULL)) {
                        ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
                        ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
                        if (dmsk->dccpms_send_ack_vector) {
                                dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
                                dp->dccps_hc_rx_ackvec = NULL;
                        }
                        dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
                        return -ENOMEM;
                }
        } else {
                /* control socket doesn't need feat nego */
                INIT_LIST_HEAD(&dmsk->dccpms_pending);
                INIT_LIST_HEAD(&dmsk->dccpms_conf);
        }

        dccp_init_xmit_timers(sk);
        icsk->icsk_rto          = DCCP_TIMEOUT_INIT;
        icsk->icsk_syn_retries  = sysctl_dccp_request_retries;
        sk->sk_state            = DCCP_CLOSED;
        sk->sk_write_space      = dccp_write_space;
        icsk->icsk_sync_mss     = dccp_sync_mss;
        dp->dccps_mss_cache     = 536;
        dp->dccps_rate_last     = jiffies;
        dp->dccps_role          = DCCP_ROLE_UNDEFINED;
        dp->dccps_service       = DCCP_SERVICE_CODE_IS_ABSENT;
        dp->dccps_l_ack_ratio   = dp->dccps_r_ack_ratio = 1;

        return 0;
}

EXPORT_SYMBOL_GPL(dccp_init_sock);

int dccp_destroy_sock(struct sock *sk)
{
        struct dccp_sock *dp = dccp_sk(sk);
        struct dccp_minisock *dmsk = dccp_msk(sk);

        /*
         * DCCP doesn't use sk_write_queue, just sk_send_head
         * for retransmissions
         */
        if (sk->sk_send_head != NULL) {
                kfree_skb(sk->sk_send_head);
                sk->sk_send_head = NULL;
        }

        /* Clean up a referenced DCCP bind bucket. */
        if (inet_csk(sk)->icsk_bind_hash != NULL)
                inet_put_port(&dccp_hashinfo, sk);

        kfree(dp->dccps_service_list);
        dp->dccps_service_list = NULL;

        if (dmsk->dccpms_send_ack_vector) {
                dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
                dp->dccps_hc_rx_ackvec = NULL;
        }
        ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
        ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
        dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;

        /* clean up feature negotiation state */
        dccp_feat_clean(dmsk);

        return 0;
}

EXPORT_SYMBOL_GPL(dccp_destroy_sock);

static inline int dccp_listen_start(struct sock *sk, int backlog)
{
        struct dccp_sock *dp = dccp_sk(sk);

        dp->dccps_role = DCCP_ROLE_LISTEN;
        return inet_csk_listen_start(sk, backlog);
}

int dccp_disconnect(struct sock *sk, int flags)
{
        struct inet_connection_sock *icsk = inet_csk(sk);
        struct inet_sock *inet = inet_sk(sk);
        int err = 0;
        const int old_state = sk->sk_state;

        if (old_state != DCCP_CLOSED)
                dccp_set_state(sk, DCCP_CLOSED);

        /* ABORT function of RFC793 */
        if (old_state == DCCP_LISTEN) {
                inet_csk_listen_stop(sk);
        /* FIXME: do the active reset thing */
        } else if (old_state == DCCP_REQUESTING)
                sk->sk_err = ECONNRESET;

        dccp_clear_xmit_timers(sk);
        __skb_queue_purge(&sk->sk_receive_queue);
        if (sk->sk_send_head != NULL) {
                __kfree_skb(sk->sk_send_head);
                sk->sk_send_head = NULL;
        }

        inet->dport = 0;

        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
                inet_reset_saddr(sk);

        sk->sk_shutdown = 0;
        sock_reset_flag(sk, SOCK_DONE);

        icsk->icsk_backoff = 0;
        inet_csk_delack_init(sk);
        __sk_dst_reset(sk);

        BUG_TRAP(!inet->num || icsk->icsk_bind_hash);

        sk->sk_error_report(sk);
        return err;
}

EXPORT_SYMBOL_GPL(dccp_disconnect);

/*
 *      Wait for a DCCP event.
 *
 *      Note that we don't need to lock the socket, as the upper poll layers
 *      take care of normal races (between the test and the event) and we don't
 *      go look at any of the socket buffers directly.
 */
unsigned int dccp_poll(struct file *file, struct socket *sock,
                       poll_table *wait)
{
        unsigned int mask;
        struct sock *sk = sock->sk;

        poll_wait(file, sk->sk_sleep, wait);
        if (sk->sk_state == DCCP_LISTEN)
                return inet_csk_listen_poll(sk);

        /* Socket is not locked. We are protected from async events
           by poll logic and correct handling of state changes
           made by another threads is impossible in any case.
         */

        mask = 0;
        if (sk->sk_err)
                mask = POLLERR;

        if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == DCCP_CLOSED)
                mask |= POLLHUP;
        if (sk->sk_shutdown & RCV_SHUTDOWN)
                mask |= POLLIN | POLLRDNORM | POLLRDHUP;

        /* Connected? */
        if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_RESPOND)) {
                if (atomic_read(&sk->sk_rmem_alloc) > 0)
                        mask |= POLLIN | POLLRDNORM;

                if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
                        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
                                mask |= POLLOUT | POLLWRNORM;
                        } else {  /* send SIGIO later */
                                set_bit(SOCK_ASYNC_NOSPACE,
                                        &sk->sk_socket->flags);
                                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);

                                /* Race breaker. If space is freed after
                                 * wspace test but before the flags are set,
                                 * IO signal will be lost.
                                 */
                                if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
                                        mask |= POLLOUT | POLLWRNORM;
                        }
                }
        }
        return mask;
}

EXPORT_SYMBOL_GPL(dccp_poll);

int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
        int rc = -ENOTCONN;

        lock_sock(sk);

        if (sk->sk_state == DCCP_LISTEN)
                goto out;

        switch (cmd) {
        case SIOCINQ: {
                struct sk_buff *skb;
                unsigned long amount = 0;

                skb = skb_peek(&sk->sk_receive_queue);
                if (skb != NULL) {
                        /*
                         * We will only return the amount of this packet since
                         * that is all that will be read.
                         */
                        amount = skb->len;
                }
                rc = put_user(amount, (int __user *)arg);
        }
                break;
        default:
                rc = -ENOIOCTLCMD;
                break;
        }
out:
        release_sock(sk);
        return rc;
}

EXPORT_SYMBOL_GPL(dccp_ioctl);

static int dccp_setsockopt_service(struct sock *sk, const __be32 service,
                                   char __user *optval, int optlen)
{
        struct dccp_sock *dp = dccp_sk(sk);
        struct dccp_service_list *sl = NULL;

        if (service == DCCP_SERVICE_INVALID_VALUE ||
            optlen > DCCP_SERVICE_LIST_MAX_LEN * sizeof(u32))
                return -EINVAL;

        if (optlen > sizeof(service)) {
                sl = kmalloc(optlen, GFP_KERNEL);
                if (sl == NULL)
                        return -ENOMEM;

                sl->dccpsl_nr = optlen / sizeof(u32) - 1;
                if (copy_from_user(sl->dccpsl_list,
                                   optval + sizeof(service),
                                   optlen - sizeof(service)) ||
                    dccp_list_has_service(sl, DCCP_SERVICE_INVALID_VALUE)) {
                        kfree(sl);
                        return -EFAULT;
                }
        }

        lock_sock(sk);
        dp->dccps_service = service;

        kfree(dp->dccps_service_list);

        dp->dccps_service_list = sl;
        release_sock(sk);
        return 0;
}

/* byte 1 is feature.  the rest is the preference list */
static int dccp_setsockopt_change(struct sock *sk, int type,
                                  struct dccp_so_feat __user *optval)
{
        struct dccp_so_feat opt;
        u8 *val;
        int rc;

        if (copy_from_user(&opt, optval, sizeof(opt)))
                return -EFAULT;

        val = kmalloc(opt.dccpsf_len, GFP_KERNEL);
        if (!val)
                return -ENOMEM;

        if (copy_from_user(val, opt.dccpsf_val, opt.dccpsf_len)) {
                rc = -EFAULT;
                goto out_free_val;
        }

        rc = dccp_feat_change(dccp_msk(sk), type, opt.dccpsf_feat,
                              val, opt.dccpsf_len, GFP_KERNEL);
        if (rc)
                goto out_free_val;

out:
        return rc;

out_free_val:
        kfree(val);
        goto out;
}

static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
                char __user *optval, int optlen)
{
        struct dccp_sock *dp = dccp_sk(sk);
        int val, err = 0;

        if (optlen < sizeof(int))
                return -EINVAL;

        if (get_user(val, (int __user *)optval))
                return -EFAULT;

        if (optname == DCCP_SOCKOPT_SERVICE)
                return dccp_setsockopt_service(sk, val, optval, optlen);

        lock_sock(sk);
        switch (optname) {
        case DCCP_SOCKOPT_PACKET_SIZE:
                DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
                err = 0;
                break;
        case DCCP_SOCKOPT_CHANGE_L:
                if (optlen != sizeof(struct dccp_so_feat))
                        err = -EINVAL;
                else
                        err = dccp_setsockopt_change(sk, DCCPO_CHANGE_L,
                                                     (struct dccp_so_feat __user *)
                                                     optval);
                break;
        case DCCP_SOCKOPT_CHANGE_R:
                if (optlen != sizeof(struct dccp_so_feat))
                        err = -EINVAL;
                else
                        err = dccp_setsockopt_change(sk, DCCPO_CHANGE_R,
                                                     (struct dccp_so_feat __user *)
                                                     optval);
                break;
        case DCCP_SOCKOPT_SEND_CSCOV:   /* sender side, RFC 4340, sec. 9.2 */
                if (val < 0 || val > 15)
                        err = -EINVAL;
                else
                        dp->dccps_pcslen = val;
                break;
        case DCCP_SOCKOPT_RECV_CSCOV:   /* receiver side, RFC 4340 sec. 9.2.1 */
                if (val < 0 || val > 15)
                        err = -EINVAL;
                else {
                        dp->dccps_pcrlen = val;
                        /* FIXME: add feature negotiation,
                         * ChangeL(MinimumChecksumCoverage, val) */
                }
                break;
        default:
                err = -ENOPROTOOPT;
                break;
        }

        release_sock(sk);
        return err;
}

int dccp_setsockopt(struct sock *sk, int level, int optname,
                    char __user *optval, int optlen)
{
        if (level != SOL_DCCP)
                return inet_csk(sk)->icsk_af_ops->setsockopt(sk, level,
                                                             optname, optval,
                                                             optlen);
        return do_dccp_setsockopt(sk, level, optname, optval, optlen);
}

EXPORT_SYMBOL_GPL(dccp_setsockopt);

#ifdef CONFIG_COMPAT
int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
                           char __user *optval, int optlen)
{
        if (level != SOL_DCCP)
                return inet_csk_compat_setsockopt(sk, level, optname,
                                                  optval, optlen);
        return do_dccp_setsockopt(sk, level, optname, optval, optlen);
}

EXPORT_SYMBOL_GPL(compat_dccp_setsockopt);
#endif

static int dccp_getsockopt_service(struct sock *sk, int len,
                                   __be32 __user *optval,
                                   int __user *optlen)
{
        const struct dccp_sock *dp = dccp_sk(sk);
        const struct dccp_service_list *sl;
        int err = -ENOENT, slen = 0, total_len = sizeof(u32);

        lock_sock(sk);
        if ((sl = dp->dccps_service_list) != NULL) {
                slen = sl->dccpsl_nr * sizeof(u32);
                total_len += slen;
        }

        err = -EINVAL;
        if (total_len > len)
                goto out;

        err = 0;
        if (put_user(total_len, optlen) ||
            put_user(dp->dccps_service, optval) ||
            (sl != NULL && copy_to_user(optval + 1, sl->dccpsl_list, slen)))
                err = -EFAULT;
out:
        release_sock(sk);
        return err;
}

static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
                    char __user *optval, int __user *optlen)
{
        struct dccp_sock *dp;
        int val, len;

        if (get_user(len, optlen))
                return -EFAULT;

        if (len < (int)sizeof(int))
                return -EINVAL;

        dp = dccp_sk(sk);

        switch (optname) {
        case DCCP_SOCKOPT_PACKET_SIZE:
                DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
                return 0;
        case DCCP_SOCKOPT_SERVICE:
                return dccp_getsockopt_service(sk, len,
                                               (__be32 __user *)optval, optlen);
        case DCCP_SOCKOPT_GET_CUR_MPS:
                val = dp->dccps_mss_cache;
                len = sizeof(val);
                break;
        case DCCP_SOCKOPT_SEND_CSCOV:
                val = dp->dccps_pcslen;
                len = sizeof(val);
                break;
        case DCCP_SOCKOPT_RECV_CSCOV:
                val = dp->dccps_pcrlen;
                len = sizeof(val);
                break;
        case 128 ... 191:
                return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,
                                             len, (u32 __user *)optval, optlen);
        case 192 ... 255:
                return ccid_hc_tx_getsockopt(dp->dccps_hc_tx_ccid, sk, optname,
                                             len, (u32 __user *)optval, optlen);
        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen) || copy_to_user(optval, &val, len))
                return -EFAULT;

        return 0;
}

int dccp_getsockopt(struct sock *sk, int level, int optname,
                    char __user *optval, int __user *optlen)
{
        if (level != SOL_DCCP)
                return inet_csk(sk)->icsk_af_ops->getsockopt(sk, level,
                                                             optname, optval,
                                                             optlen);
        return do_dccp_getsockopt(sk, level, optname, optval, optlen);
}

EXPORT_SYMBOL_GPL(dccp_getsockopt);

#ifdef CONFIG_COMPAT
int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
                           char __user *optval, int __user *optlen)
{
        if (level != SOL_DCCP)
                return inet_csk_compat_getsockopt(sk, level, optname,
                                                  optval, optlen);
        return do_dccp_getsockopt(sk, level, optname, optval, optlen);
}

EXPORT_SYMBOL_GPL(compat_dccp_getsockopt);
#endif

int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len)
{
        const struct dccp_sock *dp = dccp_sk(sk);
        const int flags = msg->msg_flags;
        const int noblock = flags & MSG_DONTWAIT;
        struct sk_buff *skb;
        int rc, size;
        long timeo;

        if (len > dp->dccps_mss_cache)
                return -EMSGSIZE;

        lock_sock(sk);

        if (sysctl_dccp_tx_qlen &&
            (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
                rc = -EAGAIN;
                goto out_release;
        }

        timeo = sock_sndtimeo(sk, noblock);

        /*
         * We have to use sk_stream_wait_connect here to set sk_write_pending,
         * so that the trick in dccp_rcv_request_sent_state_process.
         */
        /* Wait for a connection to finish. */
        if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
                if ((rc = sk_stream_wait_connect(sk, &timeo)) != 0)
                        goto out_release;

        size = sk->sk_prot->max_header + len;
        release_sock(sk);
        skb = sock_alloc_send_skb(sk, size, noblock, &rc);
        lock_sock(sk);
        if (skb == NULL)
                goto out_release;

        skb_reserve(skb, sk->sk_prot->max_header);
        rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
        if (rc != 0)
                goto out_discard;

        skb_queue_tail(&sk->sk_write_queue, skb);
        dccp_write_xmit(sk,0);
out_release:
        release_sock(sk);
        return rc ? : len;
out_discard:
        kfree_skb(skb);
        goto out_release;
}

EXPORT_SYMBOL_GPL(dccp_sendmsg);

int dccp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len, int nonblock, int flags, int *addr_len)
{
        const struct dccp_hdr *dh;
        long timeo;

        lock_sock(sk);

        if (sk->sk_state == DCCP_LISTEN) {
                len = -ENOTCONN;
                goto out;
        }

        timeo = sock_rcvtimeo(sk, nonblock);

        do {
                struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);

                if (skb == NULL)
                        goto verify_sock_status;

                dh = dccp_hdr(skb);

                if (dh->dccph_type == DCCP_PKT_DATA ||
                    dh->dccph_type == DCCP_PKT_DATAACK)
                        goto found_ok_skb;

                if (dh->dccph_type == DCCP_PKT_RESET ||
                    dh->dccph_type == DCCP_PKT_CLOSE) {
                        dccp_pr_debug("found fin ok!\n");
                        len = 0;
                        goto found_fin_ok;
                }
                dccp_pr_debug("packet_type=%s\n",
                              dccp_packet_name(dh->dccph_type));
                sk_eat_skb(sk, skb, 0);
verify_sock_status:
                if (sock_flag(sk, SOCK_DONE)) {
                        len = 0;
                        break;
                }

                if (sk->sk_err) {
                        len = sock_error(sk);
                        break;
                }

                if (sk->sk_shutdown & RCV_SHUTDOWN) {
                        len = 0;
                        break;
                }

                if (sk->sk_state == DCCP_CLOSED) {
                        if (!sock_flag(sk, SOCK_DONE)) {
                                /* This occurs when user tries to read
                                 * from never connected socket.
                                 */
                                len = -ENOTCONN;
                                break;
                        }
                        len = 0;
                        break;
                }

                if (!timeo) {
                        len = -EAGAIN;
                        break;
                }

                if (signal_pending(current)) {
                        len = sock_intr_errno(timeo);
                        break;
                }

                sk_wait_data(sk, &timeo);
                continue;
        found_ok_skb:
                if (len > skb->len)
                        len = skb->len;
                else if (len < skb->len)
                        msg->msg_flags |= MSG_TRUNC;

                if (skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len)) {
                        /* Exception. Bailout! */
                        len = -EFAULT;
                        break;
                }
        found_fin_ok:
                if (!(flags & MSG_PEEK))
                        sk_eat_skb(sk, skb, 0);
                break;
        } while (1);
out:
        release_sock(sk);
        return len;
}

EXPORT_SYMBOL_GPL(dccp_recvmsg);

int inet_dccp_listen(struct socket *sock, int backlog)
{
        struct sock *sk = sock->sk;
        unsigned char old_state;
        int err;

        lock_sock(sk);

        err = -EINVAL;
        if (sock->state != SS_UNCONNECTED || sock->type != SOCK_DCCP)
                goto out;

        old_state = sk->sk_state;
        if (!((1 << old_state) & (DCCPF_CLOSED | DCCPF_LISTEN)))
                goto out;

        /* Really, if the socket is already in listen state
         * we can only allow the backlog to be adjusted.
         */
        if (old_state != DCCP_LISTEN) {
                /*
                 * FIXME: here it probably should be sk->sk_prot->listen_start
                 * see tcp_listen_start
                 */
                err = dccp_listen_start(sk, backlog);
                if (err)
                        goto out;
        }
        sk->sk_max_ack_backlog = backlog;
        err = 0;

out:
        release_sock(sk);
        return err;
}

EXPORT_SYMBOL_GPL(inet_dccp_listen);

static const unsigned char dccp_new_state[] = {
        /* current state:   new state:      action:     */
        [0]               = DCCP_CLOSED,
        [DCCP_OPEN]       = DCCP_CLOSING | DCCP_ACTION_FIN,
        [DCCP_REQUESTING] = DCCP_CLOSED,
        [DCCP_PARTOPEN]   = DCCP_CLOSING | DCCP_ACTION_FIN,
        [DCCP_LISTEN]     = DCCP_CLOSED,
        [DCCP_RESPOND]    = DCCP_CLOSED,
        [DCCP_CLOSING]    = DCCP_CLOSED,
        [DCCP_TIME_WAIT]  = DCCP_CLOSED,
        [DCCP_CLOSED]     = DCCP_CLOSED,
};

static int dccp_close_state(struct sock *sk)
{
        const int next = dccp_new_state[sk->sk_state];
        const int ns = next & DCCP_STATE_MASK;

        if (ns != sk->sk_state)
                dccp_set_state(sk, ns);

        return next & DCCP_ACTION_FIN;
}

void dccp_close(struct sock *sk, long timeout)
{
        struct dccp_sock *dp = dccp_sk(sk);
        struct sk_buff *skb;
        int state;

        lock_sock(sk);

        sk->sk_shutdown = SHUTDOWN_MASK;

        if (sk->sk_state == DCCP_LISTEN) {
                dccp_set_state(sk, DCCP_CLOSED);

                /* Special case. */
                inet_csk_listen_stop(sk);

                goto adjudge_to_death;
        }

        sk_stop_timer(sk, &dp->dccps_xmit_timer);

        /*
         * We need to flush the recv. buffs.  We do this only on the
         * descriptor close, not protocol-sourced closes, because the
          *reader process may not have drained the data yet!
         */
        /* FIXME: check for unread data */
        while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
                __kfree_skb(skb);
        }

        if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
                /* Check zero linger _after_ checking for unread data. */
                sk->sk_prot->disconnect(sk, 0);
        } else if (dccp_close_state(sk)) {
                dccp_send_close(sk, 1);
        }

        sk_stream_wait_close(sk, timeout);

adjudge_to_death:
        state = sk->sk_state;
        sock_hold(sk);
        sock_orphan(sk);
        atomic_inc(sk->sk_prot->orphan_count);

        /*
         * It is the last release_sock in its life. It will remove backlog.
         */
        release_sock(sk);
        /*
         * Now socket is owned by kernel and we acquire BH lock
         * to finish close. No need to check for user refs.
         */
        local_bh_disable();
        bh_lock_sock(sk);
        BUG_TRAP(!sock_owned_by_user(sk));

        /* Have we already been destroyed by a softirq or backlog? */
        if (state != DCCP_CLOSED && sk->sk_state == DCCP_CLOSED)
                goto out;

        /*
         * The last release_sock may have processed the CLOSE or RESET
         * packet moving sock to CLOSED state, if not we have to fire
         * the CLOSE/CLOSEREQ retransmission timer, see "8.3. Termination"
         * in draft-ietf-dccp-spec-11. -acme
         */
        if (sk->sk_state == DCCP_CLOSING) {
                /* FIXME: should start at 2 * RTT */
                /* Timer for repeating the CLOSE/CLOSEREQ until an answer. */
                inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
                                          inet_csk(sk)->icsk_rto,
                                          DCCP_RTO_MAX);
#if 0
                /* Yeah, we should use sk->sk_prot->orphan_count, etc */
                dccp_set_state(sk, DCCP_CLOSED);
#endif
        }

        if (sk->sk_state == DCCP_CLOSED)
                inet_csk_destroy_sock(sk);

        /* Otherwise, socket is reprieved until protocol close. */

out:
        bh_unlock_sock(sk);
        local_bh_enable();
        sock_put(sk);
}

EXPORT_SYMBOL_GPL(dccp_close);

void dccp_shutdown(struct sock *sk, int how)
{
        dccp_pr_debug("entry\n");
}

EXPORT_SYMBOL_GPL(dccp_shutdown);

static int __init dccp_mib_init(void)
{
        int rc = -ENOMEM;

        dccp_statistics[0] = alloc_percpu(struct dccp_mib);
        if (dccp_statistics[0] == NULL)
                goto out;

        dccp_statistics[1] = alloc_percpu(struct dccp_mib);
        if (dccp_statistics[1] == NULL)
                goto out_free_one;

        rc = 0;
out:
        return rc;
out_free_one:
        free_percpu(dccp_statistics[0]);
        dccp_statistics[0] = NULL;
        goto out;

}

static void dccp_mib_exit(void)
{
        free_percpu(dccp_statistics[0]);
        free_percpu(dccp_statistics[1]);
        dccp_statistics[0] = dccp_statistics[1] = NULL;
}

static int thash_entries;
module_param(thash_entries, int, 0444);
MODULE_PARM_DESC(thash_entries, "Number of ehash buckets");

#ifdef CONFIG_IP_DCCP_DEBUG
int dccp_debug;
module_param(dccp_debug, bool, 0444);
MODULE_PARM_DESC(dccp_debug, "Enable debug messages");

EXPORT_SYMBOL_GPL(dccp_debug);
#endif

static int __init dccp_init(void)
{
        unsigned long goal;
        int ehash_order, bhash_order, i;
        int rc = -ENOBUFS;

        dccp_hashinfo.bind_bucket_cachep =
                kmem_cache_create("dccp_bind_bucket",
                                  sizeof(struct inet_bind_bucket), 0,
                                  SLAB_HWCACHE_ALIGN, NULL);
        if (!dccp_hashinfo.bind_bucket_cachep)
                goto out;

        /*
         * Size and allocate the main established and bind bucket
         * hash tables.
         *
         * The methodology is similar to that of the buffer cache.
         */
        if (num_physpages >= (128 * 1024))
                goal = num_physpages >> (21 - PAGE_SHIFT);
        else
                goal = num_physpages >> (23 - PAGE_SHIFT);

        if (thash_entries)
                goal = (thash_entries *
                        sizeof(struct inet_ehash_bucket)) >> PAGE_SHIFT;
        for (ehash_order = 0; (1UL << ehash_order) < goal; ehash_order++)
                ;
        do {
                dccp_hashinfo.ehash_size = (1UL << ehash_order) * PAGE_SIZE /
                                        sizeof(struct inet_ehash_bucket);
                while (dccp_hashinfo.ehash_size &
                       (dccp_hashinfo.ehash_size - 1))
                        dccp_hashinfo.ehash_size--;
                dccp_hashinfo.ehash = (struct inet_ehash_bucket *)
                        __get_free_pages(GFP_ATOMIC, ehash_order);
        } while (!dccp_hashinfo.ehash && --ehash_order > 0);

        if (!dccp_hashinfo.ehash) {
                DCCP_CRIT("Failed to allocate DCCP established hash table");
                goto out_free_bind_bucket_cachep;
        }

        for (i = 0; i < dccp_hashinfo.ehash_size; i++) {
                INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].chain);
                INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].twchain);
        }

        if (inet_ehash_locks_alloc(&dccp_hashinfo))
                        goto out_free_dccp_ehash;

        bhash_order = ehash_order;

        do {
                dccp_hashinfo.bhash_size = (1UL << bhash_order) * PAGE_SIZE /
                                        sizeof(struct inet_bind_hashbucket);
                if ((dccp_hashinfo.bhash_size > (64 * 1024)) &&
                    bhash_order > 0)
                        continue;
                dccp_hashinfo.bhash = (struct inet_bind_hashbucket *)
                        __get_free_pages(GFP_ATOMIC, bhash_order);
        } while (!dccp_hashinfo.bhash && --bhash_order >= 0);

        if (!dccp_hashinfo.bhash) {
                DCCP_CRIT("Failed to allocate DCCP bind hash table");
                goto out_free_dccp_locks;
        }

        for (i = 0; i < dccp_hashinfo.bhash_size; i++) {
                spin_lock_init(&dccp_hashinfo.bhash[i].lock);
                INIT_HLIST_HEAD(&dccp_hashinfo.bhash[i].chain);
        }

        rc = dccp_mib_init();
        if (rc)
                goto out_free_dccp_bhash;

        rc = dccp_ackvec_init();
        if (rc)
                goto out_free_dccp_mib;

        rc = dccp_sysctl_init();
        if (rc)
                goto out_ackvec_exit;

        dccp_timestamping_init();
out:
        return rc;
out_ackvec_exit:
        dccp_ackvec_exit();
out_free_dccp_mib:
        dccp_mib_exit();
out_free_dccp_bhash:
        free_pages((unsigned long)dccp_hashinfo.bhash, bhash_order);
        dccp_hashinfo.bhash = NULL;
out_free_dccp_locks:
        inet_ehash_locks_free(&dccp_hashinfo);
out_free_dccp_ehash:
        free_pages((unsigned long)dccp_hashinfo.ehash, ehash_order);
        dccp_hashinfo.ehash = NULL;
out_free_bind_bucket_cachep:
        kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
        dccp_hashinfo.bind_bucket_cachep = NULL;
        goto out;
}

static void __exit dccp_fini(void)
{
        dccp_mib_exit();
        free_pages((unsigned long)dccp_hashinfo.bhash,
                   get_order(dccp_hashinfo.bhash_size *
                             sizeof(struct inet_bind_hashbucket)));
        free_pages((unsigned long)dccp_hashinfo.ehash,
                   get_order(dccp_hashinfo.ehash_size *
                             sizeof(struct inet_ehash_bucket)));
        inet_ehash_locks_free(&dccp_hashinfo);
        kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
        dccp_ackvec_exit();
        dccp_sysctl_exit();
}

module_init(dccp_init);
module_exit(dccp_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@conectiva.com.br>");
MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");