1/*
2 *	AX.25 release 037
3 *
4 *	This code REQUIRES 2.1.15 or higher/ NET3.038
5 *
6 *	This module:
7 *		This module is free software; you can redistribute it and/or
8 *		modify it under the terms of the GNU General Public License
9 *		as published by the Free Software Foundation; either version
10 *		2 of the License, or (at your option) any later version.
11 *
12 *	History
13 *	AX.25 036	Jonathan(G4KLX)	Cloned from ax25_timer.c.
14 *			Joerg(DL1BKE)	Added DAMA Slave Timeout timer
15 *	AX.25 037	Jonathan(G4KLX)	New timer architecture.
16 */
17
18#include <linux/errno.h>
19#include <linux/types.h>
20#include <linux/socket.h>
21#include <linux/in.h>
22#include <linux/kernel.h>
23#include <linux/sched.h>
24#include <linux/timer.h>
25#include <linux/string.h>
26#include <linux/sockios.h>
27#include <linux/net.h>
28#include <net/ax25.h>
29#include <linux/inet.h>
30#include <linux/netdevice.h>
31#include <linux/skbuff.h>
32#include <net/sock.h>
33#include <asm/uaccess.h>
34#include <asm/system.h>
35#include <linux/fcntl.h>
36#include <linux/mm.h>
37#include <linux/interrupt.h>
38
39static void ax25_ds_timeout(unsigned long);
40
41/*
42 *	Add DAMA slave timeout timer to timer list.
43 *	Unlike the connection based timers the timeout function gets
44 *	triggered every second. Please note that NET_AX25_DAMA_SLAVE_TIMEOUT
45 *	(aka /proc/sys/net/ax25/{dev}/dama_slave_timeout) is still in
46 *	1/10th of a second.
47 */
48
49static void ax25_ds_add_timer(ax25_dev *ax25_dev)
50{
51	struct timer_list *t = &ax25_dev->dama.slave_timer;
52	t->data		= (unsigned long) ax25_dev;
53	t->function	= &ax25_ds_timeout;
54	t->expires	= jiffies + HZ;
55	add_timer(t);
56}
57
58void ax25_ds_del_timer(ax25_dev *ax25_dev)
59{
60	if (ax25_dev) del_timer(&ax25_dev->dama.slave_timer);
61}
62
63void ax25_ds_set_timer(ax25_dev *ax25_dev)
64{
65	if (ax25_dev == NULL)		/* paranoia */
66		return;
67
68	del_timer(&ax25_dev->dama.slave_timer);
69	ax25_dev->dama.slave_timeout = ax25_dev->values[AX25_VALUES_DS_TIMEOUT] / 10;
70	ax25_ds_add_timer(ax25_dev);
71}
72
73/*
74 *	DAMA Slave Timeout
75 *	Silently discard all (slave) connections in case our master forgot us...
76 */
77
78static void ax25_ds_timeout(unsigned long arg)
79{
80	ax25_dev *ax25_dev = (struct ax25_dev *) arg;
81	ax25_cb *ax25;
82
83	if (ax25_dev == NULL || !ax25_dev->dama.slave)
84		return;			/* Yikes! */
85
86	if (!ax25_dev->dama.slave_timeout || --ax25_dev->dama.slave_timeout) {
87		ax25_ds_set_timer(ax25_dev);
88		return;
89	}
90
91	for (ax25=ax25_list; ax25 != NULL; ax25 = ax25->next) {
92		if (ax25->ax25_dev != ax25_dev || !(ax25->condition & AX25_COND_DAMA_MODE))
93			continue;
94
95		ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
96		ax25_disconnect(ax25, ETIMEDOUT);
97	}
98
99	ax25_dev_dama_off(ax25_dev);
100}
101
102void ax25_ds_heartbeat_expiry(ax25_cb *ax25)
103{
104	switch (ax25->state) {
105
106		case AX25_STATE_0:
107			/* Magic here: If we listen() and a new link dies before it
108			   is accepted() it isn't 'dead' so doesn't get removed. */
109			if (ax25->sk == NULL || ax25->sk->destroy || (ax25->sk->state == TCP_LISTEN && ax25->sk->dead)) {
110				ax25_destroy_socket(ax25);
111				return;
112			}
113			break;
114
115		case AX25_STATE_3:
116			/*
117			 * Check the state of the receive buffer.
118			 */
119			if (ax25->sk != NULL) {
120				if (atomic_read(&ax25->sk->rmem_alloc) < (ax25->sk->rcvbuf / 2) &&
121				    (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
122					ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
123					ax25->condition &= ~AX25_COND_ACK_PENDING;
124					break;
125				}
126			}
127			break;
128	}
129
130	ax25_start_heartbeat(ax25);
131}
132
133/* dl1bke 960114: T3 works much like the IDLE timeout, but
134 *                gets reloaded with every frame for this
135 *		  connection.
136 */
137void ax25_ds_t3timer_expiry(ax25_cb *ax25)
138{
139	ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
140	ax25_dama_off(ax25);
141	ax25_disconnect(ax25, ETIMEDOUT);
142}
143
144/* dl1bke 960228: close the connection when IDLE expires.
145 *		  unlike T3 this timer gets reloaded only on
146 *		  I frames.
147 */
148void ax25_ds_idletimer_expiry(ax25_cb *ax25)
149{
150	ax25_clear_queues(ax25);
151
152	ax25->n2count = 0;
153	ax25->state = AX25_STATE_2;
154
155	ax25_calculate_t1(ax25);
156	ax25_start_t1timer(ax25);
157	ax25_stop_t3timer(ax25);
158
159	if (ax25->sk != NULL) {
160		ax25->sk->state     = TCP_CLOSE;
161		ax25->sk->err       = 0;
162		ax25->sk->shutdown |= SEND_SHUTDOWN;
163		if (!ax25->sk->dead)
164			ax25->sk->state_change(ax25->sk);
165		ax25->sk->dead      = 1;
166	}
167}
168
169/* dl1bke 960114: The DAMA protocol requires to send data and SABM/DISC
170 *                within the poll of any connected channel. Remember
171 *                that we are not allowed to send anything unless we
172 *                get polled by the Master.
173 *
174 *                Thus we'll have to do parts of our T1 handling in
175 *                ax25_enquiry_response().
176 */
177void ax25_ds_t1_timeout(ax25_cb *ax25)
178{
179	switch (ax25->state) {
180
181		case AX25_STATE_1:
182			if (ax25->n2count == ax25->n2) {
183				if (ax25->modulus == AX25_MODULUS) {
184					ax25_disconnect(ax25, ETIMEDOUT);
185					return;
186				} else {
187					ax25->modulus = AX25_MODULUS;
188					ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
189					ax25->n2count = 0;
190					ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
191				}
192			} else {
193				ax25->n2count++;
194				if (ax25->modulus == AX25_MODULUS)
195					ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
196				else
197					ax25_send_control(ax25, AX25_SABME, AX25_POLLOFF, AX25_COMMAND);
198			}
199			break;
200
201		case AX25_STATE_2:
202			if (ax25->n2count == ax25->n2) {
203				ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
204				ax25_disconnect(ax25, ETIMEDOUT);
205				return;
206			} else {
207				ax25->n2count++;
208			}
209			break;
210
211		case AX25_STATE_3:
212			if (ax25->n2count == ax25->n2) {
213				ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
214				ax25_disconnect(ax25, ETIMEDOUT);
215				return;
216			} else {
217				ax25->n2count++;
218			}
219			break;
220	}
221
222	ax25_calculate_t1(ax25);
223	ax25_start_t1timer(ax25);
224}
225