ax25_std_subr.c

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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)	Split from ax25_out.c.
 *	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>

/*
 * The following routines are taken from page 170 of the 7th ARRL Computer
 * Networking Conference paper, as is the whole state machine.
 */

void ax25_std_nr_error_recovery(ax25_cb *ax25)
{
	ax25_std_establish_data_link(ax25);
}

void ax25_std_establish_data_link(ax25_cb *ax25)
{
	ax25->condition = 0x00;
	ax25->n2count   = 0;

	if (ax25->modulus == AX25_MODULUS)
		ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
	else
		ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND);

	ax25_calculate_t1(ax25);
	ax25_stop_idletimer(ax25);
	ax25_stop_t3timer(ax25);
	ax25_stop_t2timer(ax25);
	ax25_start_t1timer(ax25);
}

void ax25_std_transmit_enquiry(ax25_cb *ax25)
{
	if (ax25->condition & AX25_COND_OWN_RX_BUSY)
		ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_COMMAND);
	else
		ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_COMMAND);

	ax25->condition &= ~AX25_COND_ACK_PENDING;

	ax25_calculate_t1(ax25);
	ax25_start_t1timer(ax25);
}
 	
void ax25_std_enquiry_response(ax25_cb *ax25)
{
	if (ax25->condition & AX25_COND_OWN_RX_BUSY)
		ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_RESPONSE);
	else
		ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_RESPONSE);

	ax25->condition &= ~AX25_COND_ACK_PENDING;
}

void ax25_std_timeout_response(ax25_cb *ax25)
{
	if (ax25->condition & AX25_COND_OWN_RX_BUSY)
		ax25_send_control(ax25, AX25_RNR, AX25_POLLOFF, AX25_RESPONSE);
	else
		ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE);

	ax25->condition &= ~AX25_COND_ACK_PENDING;
}