x25_link.c

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/*
 *  X.25 Packet Layer release 002
 *
 *  This is ALPHA test software. This code may break your machine,
 *  randomly fail to work with new releases, misbehave and/or generally
 *  screw up. It might even work.
 *
 *  This code REQUIRES 2.1.15 or higher
 *
 *  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
 *  X.25 001    Jonathan Naylor   Started coding.
 *  X.25 002    Jonathan Naylor   New timer architecture.
 *  mar/20/00   Daniela Squassoni Disabling/enabling of facilities
 *                    negotiation.
 *  2000-09-04  Henner Eisen      dev_hold() / dev_put() for x25_neigh.
 */

#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <net/x25.h>

LIST_HEAD(x25_neigh_list);
DEFINE_RWLOCK(x25_neigh_list_lock);

static void x25_t20timer_expiry(unsigned long);

static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
static void x25_transmit_restart_request(struct x25_neigh *nb);

/*
 *  Linux set/reset timer routines
 */
static inline void x25_start_t20timer(struct x25_neigh *nb)
{
    mod_timer(&nb->t20timer, jiffies + nb->t20);
}

static void x25_t20timer_expiry(unsigned long param)
{
    struct x25_neigh *nb = (struct x25_neigh *)param;

    x25_transmit_restart_request(nb);

    x25_start_t20timer(nb);
}

static inline void x25_stop_t20timer(struct x25_neigh *nb)
{
    del_timer(&nb->t20timer);
}

static inline int x25_t20timer_pending(struct x25_neigh *nb)
{
    return timer_pending(&nb->t20timer);
}

/*
 *  This handles all restart and diagnostic frames.
 */
void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
              unsigned short frametype)
{
    struct sk_buff *skbn;
    int confirm;

    switch (frametype) {
    case X25_RESTART_REQUEST:
        confirm = !x25_t20timer_pending(nb);
        x25_stop_t20timer(nb);
        nb->state = X25_LINK_STATE_3;
        if (confirm)
            x25_transmit_restart_confirmation(nb);
        break;

    case X25_RESTART_CONFIRMATION:
        x25_stop_t20timer(nb);
        nb->state = X25_LINK_STATE_3;
        break;

    case X25_DIAGNOSTIC:
        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
            break;

        printk(KERN_WARNING "x25: diagnostic #%d - %02X %02X %02X\n",
               skb->data[3], skb->data[4],
               skb->data[5], skb->data[6]);
        break;

    default:
        printk(KERN_WARNING "x25: received unknown %02X with LCI 000\n",
               frametype);
        break;
    }

    if (nb->state == X25_LINK_STATE_3)
        while ((skbn = skb_dequeue(&nb->queue)) != NULL)
            x25_send_frame(skbn, nb);
}

/*
 *  This routine is called when a Restart Request is needed
 */
static void x25_transmit_restart_request(struct x25_neigh *nb)
{
    unsigned char *dptr;
    int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
    struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);

    if (!skb)
        return;

    skb_reserve(skb, X25_MAX_L2_LEN);

    dptr = skb_put(skb, X25_STD_MIN_LEN + 2);

    *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
    *dptr++ = 0x00;
    *dptr++ = X25_RESTART_REQUEST;
    *dptr++ = 0x00;
    *dptr++ = 0;

    skb->sk = NULL;

    x25_send_frame(skb, nb);
}

/*
 * This routine is called when a Restart Confirmation is needed
 */
static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
{
    unsigned char *dptr;
    int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
    struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);

    if (!skb)
        return;

    skb_reserve(skb, X25_MAX_L2_LEN);

    dptr = skb_put(skb, X25_STD_MIN_LEN);

    *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
    *dptr++ = 0x00;
    *dptr++ = X25_RESTART_CONFIRMATION;

    skb->sk = NULL;

    x25_send_frame(skb, nb);
}

/*
 *  This routine is called when a Clear Request is needed outside of the context
 *  of a connected socket.
 */
void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
                unsigned char cause)
{
    unsigned char *dptr;
    int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
    struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);

    if (!skb)
        return;

    skb_reserve(skb, X25_MAX_L2_LEN);

    dptr = skb_put(skb, X25_STD_MIN_LEN + 2);

    *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
                     X25_GFI_EXTSEQ :
                     X25_GFI_STDSEQ);
    *dptr++ = (lci >> 0) & 0xFF;
    *dptr++ = X25_CLEAR_REQUEST;
    *dptr++ = cause;
    *dptr++ = 0x00;

    skb->sk = NULL;

    x25_send_frame(skb, nb);
}

void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
{
    switch (nb->state) {
    case X25_LINK_STATE_0:
        skb_queue_tail(&nb->queue, skb);
        nb->state = X25_LINK_STATE_1;
        x25_establish_link(nb);
        break;
    case X25_LINK_STATE_1:
    case X25_LINK_STATE_2:
        skb_queue_tail(&nb->queue, skb);
        break;
    case X25_LINK_STATE_3:
        x25_send_frame(skb, nb);
        break;
    }
}

/*
 *  Called when the link layer has become established.
 */
void x25_link_established(struct x25_neigh *nb)
{
    switch (nb->state) {
    case X25_LINK_STATE_0:
        nb->state = X25_LINK_STATE_2;
        break;
    case X25_LINK_STATE_1:
        x25_transmit_restart_request(nb);
        nb->state = X25_LINK_STATE_2;
        x25_start_t20timer(nb);
        break;
    }
}

/*
 *  Called when the link layer has terminated, or an establishment
 *  request has failed.
 */

void x25_link_terminated(struct x25_neigh *nb)
{
    nb->state = X25_LINK_STATE_0;
    /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
    x25_kill_by_neigh(nb);
}

/*
 *  Add a new device.
 */
void x25_link_device_up(struct net_device *dev)
{
    struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);

    if (!nb)
        return;

    skb_queue_head_init(&nb->queue);
    setup_timer(&nb->t20timer, x25_t20timer_expiry, (unsigned long)nb);

    dev_hold(dev);
    nb->dev      = dev;
    nb->state    = X25_LINK_STATE_0;
    nb->extended = 0;
    /*
     * Enables negotiation
     */
    nb->global_facil_mask = X25_MASK_REVERSE |
                       X25_MASK_THROUGHPUT |
                       X25_MASK_PACKET_SIZE |
                       X25_MASK_WINDOW_SIZE;
    nb->t20      = sysctl_x25_restart_request_timeout;
    atomic_set(&nb->refcnt, 1);

    write_lock_bh(&x25_neigh_list_lock);
    list_add(&nb->node, &x25_neigh_list);
    write_unlock_bh(&x25_neigh_list_lock);
}

static void __x25_remove_neigh(struct x25_neigh *nb)
{
    skb_queue_purge(&nb->queue);
    x25_stop_t20timer(nb);

    if (nb->node.next) {
        list_del(&nb->node);
        x25_neigh_put(nb);
    }
}

/*
 *  A device has been removed, remove its links.
 */
void x25_link_device_down(struct net_device *dev)
{
    struct x25_neigh *nb;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_neigh_list_lock);

    list_for_each_safe(entry, tmp, &x25_neigh_list) {
        nb = list_entry(entry, struct x25_neigh, node);

        if (nb->dev == dev) {
            __x25_remove_neigh(nb);
            dev_put(dev);
        }
    }

    write_unlock_bh(&x25_neigh_list_lock);
}

/*
 *  Given a device, return the neighbour address.
 */
struct x25_neigh *x25_get_neigh(struct net_device *dev)
{
    struct x25_neigh *nb, *use = NULL;
    struct list_head *entry;

    read_lock_bh(&x25_neigh_list_lock);
    list_for_each(entry, &x25_neigh_list) {
        nb = list_entry(entry, struct x25_neigh, node);

        if (nb->dev == dev) {
            use = nb;
            break;
        }
    }

    if (use)
        x25_neigh_hold(use);
    read_unlock_bh(&x25_neigh_list_lock);
    return use;
}

/*
 *  Handle the ioctls that control the subscription functions.
 */
int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
{
    struct x25_subscrip_struct x25_subscr;
    struct x25_neigh *nb;
    struct net_device *dev;
    int rc = -EINVAL;

    if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
        goto out;

    rc = -EFAULT;
    if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
        goto out;

    rc = -EINVAL;
    if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
        goto out;

    if ((nb = x25_get_neigh(dev)) == NULL)
        goto out_dev_put;

    dev_put(dev);

    if (cmd == SIOCX25GSUBSCRIP) {
        read_lock_bh(&x25_neigh_list_lock);
        x25_subscr.extended      = nb->extended;
        x25_subscr.global_facil_mask = nb->global_facil_mask;
        read_unlock_bh(&x25_neigh_list_lock);
        rc = copy_to_user(arg, &x25_subscr,
                  sizeof(x25_subscr)) ? -EFAULT : 0;
    } else {
        rc = -EINVAL;
        if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
            rc = 0;
            write_lock_bh(&x25_neigh_list_lock);
            nb->extended         = x25_subscr.extended;
            nb->global_facil_mask = x25_subscr.global_facil_mask;
            write_unlock_bh(&x25_neigh_list_lock);
        }
    }
    x25_neigh_put(nb);
out:
    return rc;
out_dev_put:
    dev_put(dev);
    goto out;
}


/*
 *  Release all memory associated with X.25 neighbour structures.
 */
void __exit x25_link_free(void)
{
    struct x25_neigh *nb;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_neigh_list_lock);

    list_for_each_safe(entry, tmp, &x25_neigh_list) {
        struct net_device *dev;

        nb = list_entry(entry, struct x25_neigh, node);
        dev = nb->dev;
        __x25_remove_neigh(nb);
        dev_put(dev);
    }
    write_unlock_bh(&x25_neigh_list_lock);
}