/*
 * 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.
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/spinlock.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/tcp_states.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>

static void ax25_ds_timeout(unsigned long);

/*
 *      Add DAMA slave timeout timer to timer list.
 *      Unlike the connection based timers the timeout function gets
 *      triggered every second. Please note that NET_AX25_DAMA_SLAVE_TIMEOUT
 *      (aka /proc/sys/net/ax25/{dev}/dama_slave_timeout) is still in
 *      1/10th of a second.
 */

void ax25_ds_setup_timer(ax25_dev *ax25_dev)
{
        setup_timer(&ax25_dev->dama.slave_timer, ax25_ds_timeout,
                    (unsigned long)ax25_dev);
}

void ax25_ds_del_timer(ax25_dev *ax25_dev)
{
        if (ax25_dev)
                del_timer(&ax25_dev->dama.slave_timer);
}

void ax25_ds_set_timer(ax25_dev *ax25_dev)
{
        if (ax25_dev == NULL)           /* paranoia */
                return;

        ax25_dev->dama.slave_timeout =
                msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
        mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
}

/*
 *      DAMA Slave Timeout
 *      Silently discard all (slave) connections in case our master forgot us...
 */

static void ax25_ds_timeout(unsigned long arg)
{
        ax25_dev *ax25_dev = (struct ax25_dev *) arg;
        ax25_cb *ax25;
        struct hlist_node *node;

        if (ax25_dev == NULL || !ax25_dev->dama.slave)
                return;                 /* Yikes! */

        if (!ax25_dev->dama.slave_timeout || --ax25_dev->dama.slave_timeout) {
                ax25_ds_set_timer(ax25_dev);
                return;
        }

        spin_lock(&ax25_list_lock);
        ax25_for_each(ax25, node, &ax25_list) {
                if (ax25->ax25_dev != ax25_dev || !(ax25->condition & AX25_COND_DAMA_MODE))
                        continue;

                ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
                ax25_disconnect(ax25, ETIMEDOUT);
        }
        spin_unlock(&ax25_list_lock);

        ax25_dev_dama_off(ax25_dev);
}

void ax25_ds_heartbeat_expiry(ax25_cb *ax25)
{
        struct sock *sk=ax25->sk;

        if (sk)
                bh_lock_sock(sk);

        switch (ax25->state) {

        case AX25_STATE_0:
                /* Magic here: If we listen() and a new link dies before it
                   is accepted() it isn't 'dead' so doesn't get removed. */
                if (!sk || sock_flag(sk, SOCK_DESTROY) ||
                    (sk->sk_state == TCP_LISTEN &&
                     sock_flag(sk, SOCK_DEAD))) {
                        if (sk) {
                                sock_hold(sk);
                                ax25_destroy_socket(ax25);
                                sock_put(sk);
                                bh_unlock_sock(sk);
                        } else
                                ax25_destroy_socket(ax25);
                        return;
                }
                break;

        case AX25_STATE_3:
                /*
                 * Check the state of the receive buffer.
                 */
                if (sk != NULL) {
                        if (atomic_read(&sk->sk_rmem_alloc) <
                            (sk->sk_rcvbuf >> 1) &&
                            (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
                                ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
                                ax25->condition &= ~AX25_COND_ACK_PENDING;
                                break;
                        }
                }
                break;
        }

        if (sk)
                bh_unlock_sock(sk);

        ax25_start_heartbeat(ax25);
}

/* dl1bke 960114: T3 works much like the IDLE timeout, but
 *                gets reloaded with every frame for this
 *                connection.
 */
void ax25_ds_t3timer_expiry(ax25_cb *ax25)
{
        ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
        ax25_dama_off(ax25);
        ax25_disconnect(ax25, ETIMEDOUT);
}

/* dl1bke 960228: close the connection when IDLE expires.
 *                unlike T3 this timer gets reloaded only on
 *                I frames.
 */
void ax25_ds_idletimer_expiry(ax25_cb *ax25)
{
        ax25_clear_queues(ax25);

        ax25->n2count = 0;
        ax25->state = AX25_STATE_2;

        ax25_calculate_t1(ax25);
        ax25_start_t1timer(ax25);
        ax25_stop_t3timer(ax25);

        if (ax25->sk != NULL) {
                bh_lock_sock(ax25->sk);
                ax25->sk->sk_state     = TCP_CLOSE;
                ax25->sk->sk_err       = 0;
                ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
                if (!sock_flag(ax25->sk, SOCK_DEAD)) {
                        ax25->sk->sk_state_change(ax25->sk);
                        sock_set_flag(ax25->sk, SOCK_DEAD);
                }
                bh_unlock_sock(ax25->sk);
        }
}

/* dl1bke 960114: The DAMA protocol requires to send data and SABM/DISC
 *                within the poll of any connected channel. Remember
 *                that we are not allowed to send anything unless we
 *                get polled by the Master.
 *
 *                Thus we'll have to do parts of our T1 handling in
 *                ax25_enquiry_response().
 */
void ax25_ds_t1_timeout(ax25_cb *ax25)
{
        switch (ax25->state) {
        case AX25_STATE_1:
                if (ax25->n2count == ax25->n2) {
                        if (ax25->modulus == AX25_MODULUS) {
                                ax25_disconnect(ax25, ETIMEDOUT);
                                return;
                        } else {
                                ax25->modulus = AX25_MODULUS;
                                ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
                                ax25->n2count = 0;
                                ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
                        }
                } else {
                        ax25->n2count++;
                        if (ax25->modulus == AX25_MODULUS)
                                ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
                        else
                                ax25_send_control(ax25, AX25_SABME, AX25_POLLOFF, AX25_COMMAND);
                }
                break;

        case AX25_STATE_2:
                if (ax25->n2count == ax25->n2) {
                        ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
                        ax25_disconnect(ax25, ETIMEDOUT);
                        return;
                } else {
                        ax25->n2count++;
                }
                break;

        case AX25_STATE_3:
                if (ax25->n2count == ax25->n2) {
                        ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
                        ax25_disconnect(ax25, ETIMEDOUT);
                        return;
                } else {
                        ax25->n2count++;
                }
                break;
        }

        ax25_calculate_t1(ax25);
        ax25_start_t1timer(ax25);
}