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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);
}
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