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/*

 *      AX.25 release 037

 *

 *      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.

 *

 *      Most of this code is based on the SDL diagrams published in the 7th

 *      ARRL Computer Networking Conference papers. The diagrams have mistakes

 *      in them, but are mostly correct. Before you modify the code could you

 *      read the SDL diagrams as the code is not obvious and probably very

 *      easy to break;

 *

 *      History

 *      AX.25 036       Jonathan(G4KLX) Cloned from ax25_out.c and ax25_subr.c.

 *                      Joerg(DL1BKE)   Changed ax25_ds_enquiry_response(),

 *                                      fixed ax25_dama_on() and ax25_dama_off().

 *      AX.25 037       Jonathan(G4KLX) New timer architecture.

 */

#include <linux/errno.h>

#include <linux/types.h>

#include <linux/socket.h>

#include <linux/in.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/timer.h>

#include <linux/string.h>

#include <linux/sockios.h>

#include <linux/net.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>

void ax25_ds_nr_error_recovery(ax25_cb *ax25)

{

        ax25_ds_establish_data_link(ax25);

}

/*

 *      dl1bke 960114: transmit I frames on DAMA poll

 */

void ax25_ds_enquiry_response(ax25_cb *ax25)

{

        ax25_cb *ax25o;

        /* Please note that neither DK4EG´s nor DG2FEF´s

         * DAMA spec mention the following behaviour as seen

         * with TheFirmware:

         *

         *      DB0ACH->DL1BKE <RR C P R0> [DAMA]

         *      DL1BKE->DB0ACH <I NR=0 NS=0>

         *      DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>

         *      DL1BKE->DB0ACH <RR R F R0>

         *

         * The Flexnet DAMA Master implementation apparently

         * insists on the "proper" AX.25 behaviour:

         *

         *      DB0ACH->DL1BKE <RR C P R0> [DAMA]

         *      DL1BKE->DB0ACH <RR R F R0>

         *      DL1BKE->DB0ACH <I NR=0 NS=0>

         *      DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>

         *

         * Flexnet refuses to send us *any* I frame if we send

         * a REJ in case AX25_COND_REJECT is set. It is superfluous in

         * this mode anyway (a RR or RNR invokes the retransmission).

         * Is this a Flexnet bug?

         */

        ax25_std_enquiry_response(ax25);

        if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) {

                ax25_requeue_frames(ax25);

                ax25_kick(ax25);

        }

        if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL)

                ax25_ds_t1_timeout(ax25);

        else

                ax25->n2count = 0;

        ax25_start_t3timer(ax25);

        ax25_ds_set_timer(ax25->ax25_dev);

        for (ax25o = ax25_list; ax25o != NULL; ax25o = ax25o->next) {

                if (ax25o == ax25)

                        continue;

                if (ax25o->ax25_dev != ax25->ax25_dev)

                        continue;

                if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) {

                        ax25_ds_t1_timeout(ax25o);

                        continue;

                }

                if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) {

                        ax25_requeue_frames(ax25o);

                        ax25_kick(ax25o);

                }

                if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL)

                        ax25_ds_t1_timeout(ax25o);

                /* do not start T3 for listening sockets (tnx DD8NE) */

                if (ax25o->state != AX25_STATE_0)

                        ax25_start_t3timer(ax25o);

        }

}

void ax25_ds_establish_data_link(ax25_cb *ax25)

{

        ax25->condition &= AX25_COND_DAMA_MODE;

        ax25->n2count    = 0;

        ax25_calculate_t1(ax25);

        ax25_start_t1timer(ax25);

        ax25_stop_t2timer(ax25);

        ax25_start_t3timer(ax25);

}

/*

 *      :::FIXME:::

 *      This is a kludge. Not all drivers recognize kiss commands.

 *      We need a driver level  request to switch duplex mode, that does

 *      either SCC changing, PI config or KISS as required. Currently

 *      this request isn't reliable.

 */

static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param)

{

        struct sk_buff *skb;

        unsigned char *p;

        if (ax25_dev->dev == NULL)

                return;

        if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL)

                return;

        skb->nh.raw = skb->data;

        p = skb_put(skb, 2);

        *p++ = cmd;

        *p++ = param;

        skb->dev      = ax25_dev->dev;

        skb->protocol = htons(ETH_P_AX25);

        dev_queue_xmit(skb);

}

/*

 *      A nasty problem arises if we count the number of DAMA connections

 *      wrong, especially when connections on the device already existed

 *      and our network node (or the sysop) decides to turn on DAMA Master

 *      mode. We thus flag the 'real' slave connections with

 *      ax25->dama_slave=1 and look on every disconnect if still slave

 *      connections exist.

 */

static int ax25_check_dama_slave(ax25_dev *ax25_dev)

{

        ax25_cb *ax25;

        for (ax25 = ax25_list; ax25 != NULL ; ax25 = ax25->next)

                if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1)

                        return 1;

        return 0;

}

void ax25_dev_dama_on(ax25_dev *ax25_dev)

{

        if (ax25_dev == NULL)

                return;

        if (ax25_dev->dama.slave == 0)

                ax25_kiss_cmd(ax25_dev, 5, 1);

        ax25_dev->dama.slave = 1;

        ax25_ds_set_timer(ax25_dev);

}

void ax25_dev_dama_off(ax25_dev *ax25_dev)

{

        if (ax25_dev == NULL)

                return;

        if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) {

                ax25_kiss_cmd(ax25_dev, 5, 0);

                ax25_dev->dama.slave = 0;

                ax25_ds_del_timer(ax25_dev);

        }

}

void ax25_dama_on(ax25_cb *ax25)

{

        ax25_dev_dama_on(ax25->ax25_dev);

        ax25->condition |= AX25_COND_DAMA_MODE;

}

void ax25_dama_off(ax25_cb *ax25)

{

        ax25->condition &= ~AX25_COND_DAMA_MODE;

        ax25_dev_dama_off(ax25->ax25_dev);

}