1/*
2 *	X.25 Packet Layer release 002
3 *
4 *	This is ALPHA test software. This code may break your machine,
5 *	randomly fail to work with new releases, misbehave and/or generally
6 *	screw up. It might even work.
7 *
8 *	This code REQUIRES 2.1.15 or higher
9 *
10 *	This module:
11 *		This module is free software; you can redistribute it and/or
12 *		modify it under the terms of the GNU General Public License
13 *		as published by the Free Software Foundation; either version
14 *		2 of the License, or (at your option) any later version.
15 *
16 *	History
17 *	X.25 001	Jonathan Naylor	Started coding.
18 *	X.25 002	Jonathan Naylor	New timer architecture.
19 *					Centralised disconnection processing.
20 */
21
22#include <linux/errno.h>
23#include <linux/jiffies.h>
24#include <linux/timer.h>
25#include <net/sock.h>
26#include <net/tcp_states.h>
27#include <net/x25.h>
28
29static void x25_heartbeat_expiry(unsigned long);
30static void x25_timer_expiry(unsigned long);
31
32void x25_init_timers(struct sock *sk)
33{
34	struct x25_sock *x25 = x25_sk(sk);
35
36	init_timer(&x25->timer);
37	x25->timer.data     = (unsigned long)sk;
38	x25->timer.function = &x25_timer_expiry;
39
40	/* initialized by sock_init_data */
41	sk->sk_timer.data     = (unsigned long)sk;
42	sk->sk_timer.function = &x25_heartbeat_expiry;
43}
44
45void x25_start_heartbeat(struct sock *sk)
46{
47	mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
48}
49
50void x25_stop_heartbeat(struct sock *sk)
51{
52	del_timer(&sk->sk_timer);
53}
54
55void x25_start_t2timer(struct sock *sk)
56{
57	struct x25_sock *x25 = x25_sk(sk);
58
59	mod_timer(&x25->timer, jiffies + x25->t2);
60}
61
62void x25_start_t21timer(struct sock *sk)
63{
64	struct x25_sock *x25 = x25_sk(sk);
65
66	mod_timer(&x25->timer, jiffies + x25->t21);
67}
68
69void x25_start_t22timer(struct sock *sk)
70{
71	struct x25_sock *x25 = x25_sk(sk);
72
73	mod_timer(&x25->timer, jiffies + x25->t22);
74}
75
76void x25_start_t23timer(struct sock *sk)
77{
78	struct x25_sock *x25 = x25_sk(sk);
79
80	mod_timer(&x25->timer, jiffies + x25->t23);
81}
82
83void x25_stop_timer(struct sock *sk)
84{
85	del_timer(&x25_sk(sk)->timer);
86}
87
88unsigned long x25_display_timer(struct sock *sk)
89{
90	struct x25_sock *x25 = x25_sk(sk);
91
92	if (!timer_pending(&x25->timer))
93		return 0;
94
95	return x25->timer.expires - jiffies;
96}
97
98static void x25_heartbeat_expiry(unsigned long param)
99{
100	struct sock *sk = (struct sock *)param;
101
102	bh_lock_sock(sk);
103	if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
104		goto restart_heartbeat;
105
106	switch (x25_sk(sk)->state) {
107
108		case X25_STATE_0:
109			/*
110			 * Magic here: If we listen() and a new link dies
111			 * before it is accepted() it isn't 'dead' so doesn't
112			 * get removed.
113			 */
114			if (sock_flag(sk, SOCK_DESTROY) ||
115			    (sk->sk_state == TCP_LISTEN &&
116			     sock_flag(sk, SOCK_DEAD))) {
117				bh_unlock_sock(sk);
118				x25_destroy_socket(sk);
119				return;
120			}
121			break;
122
123		case X25_STATE_3:
124			/*
125			 * Check for the state of the receive buffer.
126			 */
127			x25_check_rbuf(sk);
128			break;
129	}
130restart_heartbeat:
131	x25_start_heartbeat(sk);
132	bh_unlock_sock(sk);
133}
134
135/*
136 *	Timer has expired, it may have been T2, T21, T22, or T23. We can tell
137 *	by the state machine state.
138 */
139static inline void x25_do_timer_expiry(struct sock * sk)
140{
141	struct x25_sock *x25 = x25_sk(sk);
142
143	switch (x25->state) {
144
145		case X25_STATE_3:	/* T2 */
146			if (x25->condition & X25_COND_ACK_PENDING) {
147				x25->condition &= ~X25_COND_ACK_PENDING;
148				x25_enquiry_response(sk);
149			}
150			break;
151
152		case X25_STATE_1:	/* T21 */
153		case X25_STATE_4:	/* T22 */
154			x25_write_internal(sk, X25_CLEAR_REQUEST);
155			x25->state = X25_STATE_2;
156			x25_start_t23timer(sk);
157			break;
158
159		case X25_STATE_2:	/* T23 */
160			x25_disconnect(sk, ETIMEDOUT, 0, 0);
161			break;
162	}
163}
164
165static void x25_timer_expiry(unsigned long param)
166{
167	struct sock *sk = (struct sock *)param;
168
169	bh_lock_sock(sk);
170	if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
171		if (x25_sk(sk)->state == X25_STATE_3)
172			x25_start_t2timer(sk);
173	} else
174		x25_do_timer_expiry(sk);
175	bh_unlock_sock(sk);
176}
177