1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
9 */
10#include <linux/errno.h>
11#include <linux/types.h>
12#include <linux/socket.h>
13#include <linux/spinlock.h>
14#include <linux/in.h>
15#include <linux/kernel.h>
16#include <linux/jiffies.h>
17#include <linux/timer.h>
18#include <linux/string.h>
19#include <linux/sockios.h>
20#include <linux/net.h>
21#include <net/tcp_states.h>
22#include <net/ax25.h>
23#include <linux/inet.h>
24#include <linux/netdevice.h>
25#include <linux/skbuff.h>
26#include <net/sock.h>
27#include <asm/uaccess.h>
28#include <linux/fcntl.h>
29#include <linux/mm.h>
30#include <linux/interrupt.h>
31
32static void ax25_ds_timeout(unsigned long);
33
34/*
35 *	Add DAMA slave timeout timer to timer list.
36 *	Unlike the connection based timers the timeout function gets
37 *	triggered every second. Please note that NET_AX25_DAMA_SLAVE_TIMEOUT
38 *	(aka /proc/sys/net/ax25/{dev}/dama_slave_timeout) is still in
39 *	1/10th of a second.
40 */
41
42void ax25_ds_setup_timer(ax25_dev *ax25_dev)
43{
44	setup_timer(&ax25_dev->dama.slave_timer, ax25_ds_timeout,
45		    (unsigned long)ax25_dev);
46}
47
48void ax25_ds_del_timer(ax25_dev *ax25_dev)
49{
50	if (ax25_dev)
51		del_timer(&ax25_dev->dama.slave_timer);
52}
53
54void ax25_ds_set_timer(ax25_dev *ax25_dev)
55{
56	if (ax25_dev == NULL)		/* paranoia */
57		return;
58
59	ax25_dev->dama.slave_timeout =
60		msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
61	mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
62}
63
64/*
65 *	DAMA Slave Timeout
66 *	Silently discard all (slave) connections in case our master forgot us...
67 */
68
69static void ax25_ds_timeout(unsigned long arg)
70{
71	ax25_dev *ax25_dev = (struct ax25_dev *) arg;
72	ax25_cb *ax25;
73
74	if (ax25_dev == NULL || !ax25_dev->dama.slave)
75		return;			/* Yikes! */
76
77	if (!ax25_dev->dama.slave_timeout || --ax25_dev->dama.slave_timeout) {
78		ax25_ds_set_timer(ax25_dev);
79		return;
80	}
81
82	spin_lock(&ax25_list_lock);
83	ax25_for_each(ax25, &ax25_list) {
84		if (ax25->ax25_dev != ax25_dev || !(ax25->condition & AX25_COND_DAMA_MODE))
85			continue;
86
87		ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
88		ax25_disconnect(ax25, ETIMEDOUT);
89	}
90	spin_unlock(&ax25_list_lock);
91
92	ax25_dev_dama_off(ax25_dev);
93}
94
95void ax25_ds_heartbeat_expiry(ax25_cb *ax25)
96{
97	struct sock *sk=ax25->sk;
98
99	if (sk)
100		bh_lock_sock(sk);
101
102	switch (ax25->state) {
103
104	case AX25_STATE_0:
105		/* Magic here: If we listen() and a new link dies before it
106		   is accepted() it isn't 'dead' so doesn't get removed. */
107		if (!sk || sock_flag(sk, SOCK_DESTROY) ||
108		    (sk->sk_state == TCP_LISTEN &&
109		     sock_flag(sk, SOCK_DEAD))) {
110			if (sk) {
111				sock_hold(sk);
112				ax25_destroy_socket(ax25);
113				bh_unlock_sock(sk);
114				sock_put(sk);
115			} else
116				ax25_destroy_socket(ax25);
117			return;
118		}
119		break;
120
121	case AX25_STATE_3:
122		/*
123		 * Check the state of the receive buffer.
124		 */
125		if (sk != NULL) {
126			if (atomic_read(&sk->sk_rmem_alloc) <
127			    (sk->sk_rcvbuf >> 1) &&
128			    (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
129				ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
130				ax25->condition &= ~AX25_COND_ACK_PENDING;
131				break;
132			}
133		}
134		break;
135	}
136
137	if (sk)
138		bh_unlock_sock(sk);
139
140	ax25_start_heartbeat(ax25);
141}
142
143/* dl1bke 960114: T3 works much like the IDLE timeout, but
144 *                gets reloaded with every frame for this
145 *		  connection.
146 */
147void ax25_ds_t3timer_expiry(ax25_cb *ax25)
148{
149	ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
150	ax25_dama_off(ax25);
151	ax25_disconnect(ax25, ETIMEDOUT);
152}
153
154/* dl1bke 960228: close the connection when IDLE expires.
155 *		  unlike T3 this timer gets reloaded only on
156 *		  I frames.
157 */
158void ax25_ds_idletimer_expiry(ax25_cb *ax25)
159{
160	ax25_clear_queues(ax25);
161
162	ax25->n2count = 0;
163	ax25->state = AX25_STATE_2;
164
165	ax25_calculate_t1(ax25);
166	ax25_start_t1timer(ax25);
167	ax25_stop_t3timer(ax25);
168
169	if (ax25->sk != NULL) {
170		bh_lock_sock(ax25->sk);
171		ax25->sk->sk_state     = TCP_CLOSE;
172		ax25->sk->sk_err       = 0;
173		ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
174		if (!sock_flag(ax25->sk, SOCK_DEAD)) {
175			ax25->sk->sk_state_change(ax25->sk);
176			sock_set_flag(ax25->sk, SOCK_DEAD);
177		}
178		bh_unlock_sock(ax25->sk);
179	}
180}
181
182/* dl1bke 960114: The DAMA protocol requires to send data and SABM/DISC
183 *                within the poll of any connected channel. Remember
184 *                that we are not allowed to send anything unless we
185 *                get polled by the Master.
186 *
187 *                Thus we'll have to do parts of our T1 handling in
188 *                ax25_enquiry_response().
189 */
190void ax25_ds_t1_timeout(ax25_cb *ax25)
191{
192	switch (ax25->state) {
193	case AX25_STATE_1:
194		if (ax25->n2count == ax25->n2) {
195			if (ax25->modulus == AX25_MODULUS) {
196				ax25_disconnect(ax25, ETIMEDOUT);
197				return;
198			} else {
199				ax25->modulus = AX25_MODULUS;
200				ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
201				ax25->n2count = 0;
202				ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
203			}
204		} else {
205			ax25->n2count++;
206			if (ax25->modulus == AX25_MODULUS)
207				ax25_send_control(ax25, AX25_SABM, AX25_POLLOFF, AX25_COMMAND);
208			else
209				ax25_send_control(ax25, AX25_SABME, AX25_POLLOFF, AX25_COMMAND);
210		}
211		break;
212
213	case AX25_STATE_2:
214		if (ax25->n2count == ax25->n2) {
215			ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
216			ax25_disconnect(ax25, ETIMEDOUT);
217			return;
218		} else {
219			ax25->n2count++;
220		}
221		break;
222
223	case AX25_STATE_3:
224		if (ax25->n2count == ax25->n2) {
225			ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
226			ax25_disconnect(ax25, ETIMEDOUT);
227			return;
228		} else {
229			ax25->n2count++;
230		}
231		break;
232	}
233
234	ax25_calculate_t1(ax25);
235	ax25_start_t1timer(ax25);
236}
237