ax25_ds_timer.c

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/*
 * 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 ([email protected])
 * Copyright (C) Joerg Reuter DL1BKE ([email protected])
 */
#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 <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);
                bh_unlock_sock(sk);
                sock_put(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);
}