lapb_iface.c

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/*
 *  LAPB release 002
 *
 *  This code REQUIRES 2.1.15 or higher/ NET3.038
 *
 *  This module:
 *      This module 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.
 *
 *  History
 *  LAPB 001    Jonathan Naylor Started Coding
 *  LAPB 002    Jonathan Naylor New timer architecture.
 *  2000-10-29  Henner Eisen    lapb_data_indication() return status.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.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 <linux/inet.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <net/lapb.h>

static LIST_HEAD(lapb_list);
static DEFINE_RWLOCK(lapb_list_lock);

/*
 *  Free an allocated lapb control block.
 */
static void lapb_free_cb(struct lapb_cb *lapb)
{
    kfree(lapb);
}

static __inline__ void lapb_hold(struct lapb_cb *lapb)
{
    atomic_inc(&lapb->refcnt);
}

static __inline__ void lapb_put(struct lapb_cb *lapb)
{
    if (atomic_dec_and_test(&lapb->refcnt))
        lapb_free_cb(lapb);
}

/*
 *  Socket removal during an interrupt is now safe.
 */
static void __lapb_remove_cb(struct lapb_cb *lapb)
{
    if (lapb->node.next) {
        list_del(&lapb->node);
        lapb_put(lapb);
    }
}

/*
 *  Add a socket to the bound sockets list.
 */
static void __lapb_insert_cb(struct lapb_cb *lapb)
{
    list_add(&lapb->node, &lapb_list);
    lapb_hold(lapb);
}

static struct lapb_cb *__lapb_devtostruct(struct net_device *dev)
{
    struct list_head *entry;
    struct lapb_cb *lapb, *use = NULL;

    list_for_each(entry, &lapb_list) {
        lapb = list_entry(entry, struct lapb_cb, node);
        if (lapb->dev == dev) {
            use = lapb;
            break;
        }
    }

    if (use)
        lapb_hold(use);

    return use;
}

static struct lapb_cb *lapb_devtostruct(struct net_device *dev)
{
    struct lapb_cb *rc;

    read_lock_bh(&lapb_list_lock);
    rc = __lapb_devtostruct(dev);
    read_unlock_bh(&lapb_list_lock);

    return rc;
}
/*
 *  Create an empty LAPB control block.
 */
static struct lapb_cb *lapb_create_cb(void)
{
    struct lapb_cb *lapb = kzalloc(sizeof(*lapb), GFP_ATOMIC);


    if (!lapb)
        goto out;

    skb_queue_head_init(&lapb->write_queue);
    skb_queue_head_init(&lapb->ack_queue);

    init_timer(&lapb->t1timer);
    init_timer(&lapb->t2timer);

    lapb->t1      = LAPB_DEFAULT_T1;
    lapb->t2      = LAPB_DEFAULT_T2;
    lapb->n2      = LAPB_DEFAULT_N2;
    lapb->mode    = LAPB_DEFAULT_MODE;
    lapb->window  = LAPB_DEFAULT_WINDOW;
    lapb->state   = LAPB_STATE_0;
    atomic_set(&lapb->refcnt, 1);
out:
    return lapb;
}

int lapb_register(struct net_device *dev,
          const struct lapb_register_struct *callbacks)
{
    struct lapb_cb *lapb;
    int rc = LAPB_BADTOKEN;

    write_lock_bh(&lapb_list_lock);

    lapb = __lapb_devtostruct(dev);
    if (lapb) {
        lapb_put(lapb);
        goto out;
    }

    lapb = lapb_create_cb();
    rc = LAPB_NOMEM;
    if (!lapb)
        goto out;

    lapb->dev       = dev;
    lapb->callbacks = callbacks;

    __lapb_insert_cb(lapb);

    lapb_start_t1timer(lapb);

    rc = LAPB_OK;
out:
    write_unlock_bh(&lapb_list_lock);
    return rc;
}

int lapb_unregister(struct net_device *dev)
{
    struct lapb_cb *lapb;
    int rc = LAPB_BADTOKEN;

    write_lock_bh(&lapb_list_lock);
    lapb = __lapb_devtostruct(dev);
    if (!lapb)
        goto out;

    lapb_stop_t1timer(lapb);
    lapb_stop_t2timer(lapb);

    lapb_clear_queues(lapb);

    __lapb_remove_cb(lapb);

    lapb_put(lapb);
    rc = LAPB_OK;
out:
    write_unlock_bh(&lapb_list_lock);
    return rc;
}

int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms)
{
    int rc = LAPB_BADTOKEN;
    struct lapb_cb *lapb = lapb_devtostruct(dev);

    if (!lapb)
        goto out;

    parms->t1      = lapb->t1 / HZ;
    parms->t2      = lapb->t2 / HZ;
    parms->n2      = lapb->n2;
    parms->n2count = lapb->n2count;
    parms->state   = lapb->state;
    parms->window  = lapb->window;
    parms->mode    = lapb->mode;

    if (!timer_pending(&lapb->t1timer))
        parms->t1timer = 0;
    else
        parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;

    if (!timer_pending(&lapb->t2timer))
        parms->t2timer = 0;
    else
        parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;

    lapb_put(lapb);
    rc = LAPB_OK;
out:
    return rc;
}

int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
{
    int rc = LAPB_BADTOKEN;
    struct lapb_cb *lapb = lapb_devtostruct(dev);

    if (!lapb)
        goto out;

    rc = LAPB_INVALUE;
    if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1)
        goto out_put;

    if (lapb->state == LAPB_STATE_0) {
        if (parms->mode & LAPB_EXTENDED) {
            if (parms->window < 1 || parms->window > 127)
                goto out_put;
        } else {
            if (parms->window < 1 || parms->window > 7)
                goto out_put;
        }
        lapb->mode    = parms->mode;
        lapb->window  = parms->window;
    }

    lapb->t1    = parms->t1 * HZ;
    lapb->t2    = parms->t2 * HZ;
    lapb->n2    = parms->n2;

    rc = LAPB_OK;
out_put:
    lapb_put(lapb);
out:
    return rc;
}

int lapb_connect_request(struct net_device *dev)
{
    struct lapb_cb *lapb = lapb_devtostruct(dev);
    int rc = LAPB_BADTOKEN;

    if (!lapb)
        goto out;

    rc = LAPB_OK;
    if (lapb->state == LAPB_STATE_1)
        goto out_put;

    rc = LAPB_CONNECTED;
    if (lapb->state == LAPB_STATE_3 || lapb->state == LAPB_STATE_4)
        goto out_put;

    lapb_establish_data_link(lapb);

    lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
    lapb->state = LAPB_STATE_1;

    rc = LAPB_OK;
out_put:
    lapb_put(lapb);
out:
    return rc;
}

int lapb_disconnect_request(struct net_device *dev)
{
    struct lapb_cb *lapb = lapb_devtostruct(dev);
    int rc = LAPB_BADTOKEN;

    if (!lapb)
        goto out;

    switch (lapb->state) {
    case LAPB_STATE_0:
        rc = LAPB_NOTCONNECTED;
        goto out_put;

    case LAPB_STATE_1:
        lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
        lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
        lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
        lapb->state = LAPB_STATE_0;
        lapb_start_t1timer(lapb);
        rc = LAPB_NOTCONNECTED;
        goto out_put;

    case LAPB_STATE_2:
        rc = LAPB_OK;
        goto out_put;
    }

    lapb_clear_queues(lapb);
    lapb->n2count = 0;
    lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
    lapb_start_t1timer(lapb);
    lapb_stop_t2timer(lapb);
    lapb->state = LAPB_STATE_2;

    lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
    lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);

    rc = LAPB_OK;
out_put:
    lapb_put(lapb);
out:
    return rc;
}

int lapb_data_request(struct net_device *dev, struct sk_buff *skb)
{
    struct lapb_cb *lapb = lapb_devtostruct(dev);
    int rc = LAPB_BADTOKEN;

    if (!lapb)
        goto out;

    rc = LAPB_NOTCONNECTED;
    if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
        goto out_put;

    skb_queue_tail(&lapb->write_queue, skb);
    lapb_kick(lapb);
    rc = LAPB_OK;
out_put:
    lapb_put(lapb);
out:
    return rc;
}

int lapb_data_received(struct net_device *dev, struct sk_buff *skb)
{
    struct lapb_cb *lapb = lapb_devtostruct(dev);
    int rc = LAPB_BADTOKEN;

    if (lapb) {
        lapb_data_input(lapb, skb);
        lapb_put(lapb);
        rc = LAPB_OK;
    }

    return rc;
}

void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
{
    if (lapb->callbacks->connect_confirmation)
        lapb->callbacks->connect_confirmation(lapb->dev, reason);
}

void lapb_connect_indication(struct lapb_cb *lapb, int reason)
{
    if (lapb->callbacks->connect_indication)
        lapb->callbacks->connect_indication(lapb->dev, reason);
}

void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
{
    if (lapb->callbacks->disconnect_confirmation)
        lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
}

void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
{
    if (lapb->callbacks->disconnect_indication)
        lapb->callbacks->disconnect_indication(lapb->dev, reason);
}

int lapb_data_indication(struct lapb_cb *lapb, struct sk_buff *skb)
{
    if (lapb->callbacks->data_indication)
        return lapb->callbacks->data_indication(lapb->dev, skb);

    kfree_skb(skb);
    return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
}

int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb)
{
    int used = 0;

    if (lapb->callbacks->data_transmit) {
        lapb->callbacks->data_transmit(lapb->dev, skb);
        used = 1;
    }

    return used;
}

EXPORT_SYMBOL(lapb_register);
EXPORT_SYMBOL(lapb_unregister);
EXPORT_SYMBOL(lapb_getparms);
EXPORT_SYMBOL(lapb_setparms);
EXPORT_SYMBOL(lapb_connect_request);
EXPORT_SYMBOL(lapb_disconnect_request);
EXPORT_SYMBOL(lapb_data_request);
EXPORT_SYMBOL(lapb_data_received);

static int __init lapb_init(void)
{
    return 0;
}

static void __exit lapb_exit(void)
{
    WARN_ON(!list_empty(&lapb_list));
}

MODULE_AUTHOR("Jonathan Naylor <[email protected]>");
MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
MODULE_LICENSE("GPL");

module_init(lapb_init);
module_exit(lapb_exit);