rose_link.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])
 */
#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/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/netfilter.h>
#include <net/rose.h>

static void rose_ftimer_expiry(unsigned long);
static void rose_t0timer_expiry(unsigned long);

static void rose_transmit_restart_confirmation(struct rose_neigh *neigh);
static void rose_transmit_restart_request(struct rose_neigh *neigh);

void rose_start_ftimer(struct rose_neigh *neigh)
{
    del_timer(&neigh->ftimer);

    neigh->ftimer.data     = (unsigned long)neigh;
    neigh->ftimer.function = &rose_ftimer_expiry;
    neigh->ftimer.expires  =
        jiffies + msecs_to_jiffies(sysctl_rose_link_fail_timeout);

    add_timer(&neigh->ftimer);
}

static void rose_start_t0timer(struct rose_neigh *neigh)
{
    del_timer(&neigh->t0timer);

    neigh->t0timer.data     = (unsigned long)neigh;
    neigh->t0timer.function = &rose_t0timer_expiry;
    neigh->t0timer.expires  =
        jiffies + msecs_to_jiffies(sysctl_rose_restart_request_timeout);

    add_timer(&neigh->t0timer);
}

void rose_stop_ftimer(struct rose_neigh *neigh)
{
    del_timer(&neigh->ftimer);
}

void rose_stop_t0timer(struct rose_neigh *neigh)
{
    del_timer(&neigh->t0timer);
}

int rose_ftimer_running(struct rose_neigh *neigh)
{
    return timer_pending(&neigh->ftimer);
}

static int rose_t0timer_running(struct rose_neigh *neigh)
{
    return timer_pending(&neigh->t0timer);
}

static void rose_ftimer_expiry(unsigned long param)
{
}

static void rose_t0timer_expiry(unsigned long param)
{
    struct rose_neigh *neigh = (struct rose_neigh *)param;

    rose_transmit_restart_request(neigh);

    neigh->dce_mode = 0;

    rose_start_t0timer(neigh);
}

/*
 *  Interface to ax25_send_frame. Changes my level 2 callsign depending
 *  on whether we have a global ROSE callsign or use the default port
 *  callsign.
 */
static int rose_send_frame(struct sk_buff *skb, struct rose_neigh *neigh)
{
    ax25_address *rose_call;
    ax25_cb *ax25s;

    if (ax25cmp(&rose_callsign, &null_ax25_address) == 0)
        rose_call = (ax25_address *)neigh->dev->dev_addr;
    else
        rose_call = &rose_callsign;

    ax25s = neigh->ax25;
    neigh->ax25 = ax25_send_frame(skb, 260, rose_call, &neigh->callsign, neigh->digipeat, neigh->dev);
    if (ax25s)
        ax25_cb_put(ax25s);

    return neigh->ax25 != NULL;
}

/*
 *  Interface to ax25_link_up. Changes my level 2 callsign depending
 *  on whether we have a global ROSE callsign or use the default port
 *  callsign.
 */
static int rose_link_up(struct rose_neigh *neigh)
{
    ax25_address *rose_call;
    ax25_cb *ax25s;

    if (ax25cmp(&rose_callsign, &null_ax25_address) == 0)
        rose_call = (ax25_address *)neigh->dev->dev_addr;
    else
        rose_call = &rose_callsign;

    ax25s = neigh->ax25;
    neigh->ax25 = ax25_find_cb(rose_call, &neigh->callsign, neigh->digipeat, neigh->dev);
    if (ax25s)
        ax25_cb_put(ax25s);

    return neigh->ax25 != NULL;
}

/*
 *  This handles all restart and diagnostic frames.
 */
void rose_link_rx_restart(struct sk_buff *skb, struct rose_neigh *neigh, unsigned short frametype)
{
    struct sk_buff *skbn;

    switch (frametype) {
    case ROSE_RESTART_REQUEST:
        rose_stop_t0timer(neigh);
        neigh->restarted = 1;
        neigh->dce_mode  = (skb->data[3] == ROSE_DTE_ORIGINATED);
        rose_transmit_restart_confirmation(neigh);
        break;

    case ROSE_RESTART_CONFIRMATION:
        rose_stop_t0timer(neigh);
        neigh->restarted = 1;
        break;

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

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

    if (neigh->restarted) {
        while ((skbn = skb_dequeue(&neigh->queue)) != NULL)
            if (!rose_send_frame(skbn, neigh))
                kfree_skb(skbn);
    }
}

/*
 *  This routine is called when a Restart Request is needed
 */
static void rose_transmit_restart_request(struct rose_neigh *neigh)
{
    struct sk_buff *skb;
    unsigned char *dptr;
    int len;

    len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 3;

    if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
        return;

    skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

    dptr = skb_put(skb, ROSE_MIN_LEN + 3);

    *dptr++ = AX25_P_ROSE;
    *dptr++ = ROSE_GFI;
    *dptr++ = 0x00;
    *dptr++ = ROSE_RESTART_REQUEST;
    *dptr++ = ROSE_DTE_ORIGINATED;
    *dptr++ = 0;

    if (!rose_send_frame(skb, neigh))
        kfree_skb(skb);
}

/*
 * This routine is called when a Restart Confirmation is needed
 */
static void rose_transmit_restart_confirmation(struct rose_neigh *neigh)
{
    struct sk_buff *skb;
    unsigned char *dptr;
    int len;

    len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 1;

    if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
        return;

    skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

    dptr = skb_put(skb, ROSE_MIN_LEN + 1);

    *dptr++ = AX25_P_ROSE;
    *dptr++ = ROSE_GFI;
    *dptr++ = 0x00;
    *dptr++ = ROSE_RESTART_CONFIRMATION;

    if (!rose_send_frame(skb, neigh))
        kfree_skb(skb);
}

/*
 * This routine is called when a Clear Request is needed outside of the context
 * of a connected socket.
 */
void rose_transmit_clear_request(struct rose_neigh *neigh, unsigned int lci, unsigned char cause, unsigned char diagnostic)
{
    struct sk_buff *skb;
    unsigned char *dptr;
    int len;

    len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 3;

    if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
        return;

    skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

    dptr = skb_put(skb, ROSE_MIN_LEN + 3);

    *dptr++ = AX25_P_ROSE;
    *dptr++ = ((lci >> 8) & 0x0F) | ROSE_GFI;
    *dptr++ = ((lci >> 0) & 0xFF);
    *dptr++ = ROSE_CLEAR_REQUEST;
    *dptr++ = cause;
    *dptr++ = diagnostic;

    if (!rose_send_frame(skb, neigh))
        kfree_skb(skb);
}

void rose_transmit_link(struct sk_buff *skb, struct rose_neigh *neigh)
{
    unsigned char *dptr;

    if (neigh->loopback) {
        rose_loopback_queue(skb, neigh);
        return;
    }

    if (!rose_link_up(neigh))
        neigh->restarted = 0;

    dptr = skb_push(skb, 1);
    *dptr++ = AX25_P_ROSE;

    if (neigh->restarted) {
        if (!rose_send_frame(skb, neigh))
            kfree_skb(skb);
    } else {
        skb_queue_tail(&neigh->queue, skb);

        if (!rose_t0timer_running(neigh)) {
            rose_transmit_restart_request(neigh);
            neigh->dce_mode = 0;
            rose_start_t0timer(neigh);
        }
    }
}