1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * X.25 Packet Layer release 002 |
4 | * |
5 | * This is ALPHA test software. This code may break your machine, |
6 | * randomly fail to work with new releases, misbehave and/or generally |
7 | * screw up. It might even work. |
8 | * |
9 | * This code REQUIRES 2.1.15 or higher |
10 | * |
11 | * History |
12 | * X.25 001 Jonathan Naylor Started coding. |
13 | * X.25 002 Jonathan Naylor New timer architecture. |
14 | * Centralised disconnection processing. |
15 | */ |
16 | |
17 | #include <linux/errno.h> |
18 | #include <linux/jiffies.h> |
19 | #include <linux/timer.h> |
20 | #include <net/sock.h> |
21 | #include <net/tcp_states.h> |
22 | #include <net/x25.h> |
23 | |
24 | static void x25_heartbeat_expiry(struct timer_list *t); |
25 | static void x25_timer_expiry(struct timer_list *t); |
26 | |
27 | void x25_init_timers(struct sock *sk) |
28 | { |
29 | struct x25_sock *x25 = x25_sk(sk); |
30 | |
31 | timer_setup(&x25->timer, x25_timer_expiry, 0); |
32 | |
33 | /* initialized by sock_init_data */ |
34 | sk->sk_timer.function = x25_heartbeat_expiry; |
35 | } |
36 | |
37 | void x25_start_heartbeat(struct sock *sk) |
38 | { |
39 | mod_timer(timer: &sk->sk_timer, expires: jiffies + 5 * HZ); |
40 | } |
41 | |
42 | void x25_stop_heartbeat(struct sock *sk) |
43 | { |
44 | del_timer(timer: &sk->sk_timer); |
45 | } |
46 | |
47 | void x25_start_t2timer(struct sock *sk) |
48 | { |
49 | struct x25_sock *x25 = x25_sk(sk); |
50 | |
51 | mod_timer(timer: &x25->timer, expires: jiffies + x25->t2); |
52 | } |
53 | |
54 | void x25_start_t21timer(struct sock *sk) |
55 | { |
56 | struct x25_sock *x25 = x25_sk(sk); |
57 | |
58 | mod_timer(timer: &x25->timer, expires: jiffies + x25->t21); |
59 | } |
60 | |
61 | void x25_start_t22timer(struct sock *sk) |
62 | { |
63 | struct x25_sock *x25 = x25_sk(sk); |
64 | |
65 | mod_timer(timer: &x25->timer, expires: jiffies + x25->t22); |
66 | } |
67 | |
68 | void x25_start_t23timer(struct sock *sk) |
69 | { |
70 | struct x25_sock *x25 = x25_sk(sk); |
71 | |
72 | mod_timer(timer: &x25->timer, expires: jiffies + x25->t23); |
73 | } |
74 | |
75 | void x25_stop_timer(struct sock *sk) |
76 | { |
77 | del_timer(timer: &x25_sk(sk)->timer); |
78 | } |
79 | |
80 | unsigned long x25_display_timer(struct sock *sk) |
81 | { |
82 | struct x25_sock *x25 = x25_sk(sk); |
83 | |
84 | if (!timer_pending(timer: &x25->timer)) |
85 | return 0; |
86 | |
87 | return x25->timer.expires - jiffies; |
88 | } |
89 | |
90 | static void x25_heartbeat_expiry(struct timer_list *t) |
91 | { |
92 | struct sock *sk = from_timer(sk, t, sk_timer); |
93 | |
94 | bh_lock_sock(sk); |
95 | if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */ |
96 | goto restart_heartbeat; |
97 | |
98 | switch (x25_sk(sk)->state) { |
99 | |
100 | case X25_STATE_0: |
101 | /* |
102 | * Magic here: If we listen() and a new link dies |
103 | * before it is accepted() it isn't 'dead' so doesn't |
104 | * get removed. |
105 | */ |
106 | if (sock_flag(sk, flag: SOCK_DESTROY) || |
107 | (sk->sk_state == TCP_LISTEN && |
108 | sock_flag(sk, flag: SOCK_DEAD))) { |
109 | bh_unlock_sock(sk); |
110 | x25_destroy_socket_from_timer(sk); |
111 | return; |
112 | } |
113 | break; |
114 | |
115 | case X25_STATE_3: |
116 | /* |
117 | * Check for the state of the receive buffer. |
118 | */ |
119 | x25_check_rbuf(sk); |
120 | break; |
121 | } |
122 | restart_heartbeat: |
123 | x25_start_heartbeat(sk); |
124 | bh_unlock_sock(sk); |
125 | } |
126 | |
127 | /* |
128 | * Timer has expired, it may have been T2, T21, T22, or T23. We can tell |
129 | * by the state machine state. |
130 | */ |
131 | static inline void x25_do_timer_expiry(struct sock * sk) |
132 | { |
133 | struct x25_sock *x25 = x25_sk(sk); |
134 | |
135 | switch (x25->state) { |
136 | |
137 | case X25_STATE_3: /* T2 */ |
138 | if (x25->condition & X25_COND_ACK_PENDING) { |
139 | x25->condition &= ~X25_COND_ACK_PENDING; |
140 | x25_enquiry_response(sk); |
141 | } |
142 | break; |
143 | |
144 | case X25_STATE_1: /* T21 */ |
145 | case X25_STATE_4: /* T22 */ |
146 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
147 | x25->state = X25_STATE_2; |
148 | x25_start_t23timer(sk); |
149 | break; |
150 | |
151 | case X25_STATE_2: /* T23 */ |
152 | x25_disconnect(sk, ETIMEDOUT, 0, 0); |
153 | break; |
154 | } |
155 | } |
156 | |
157 | static void x25_timer_expiry(struct timer_list *t) |
158 | { |
159 | struct x25_sock *x25 = from_timer(x25, t, timer); |
160 | struct sock *sk = &x25->sk; |
161 | |
162 | bh_lock_sock(sk); |
163 | if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */ |
164 | if (x25_sk(sk)->state == X25_STATE_3) |
165 | x25_start_t2timer(sk); |
166 | } else |
167 | x25_do_timer_expiry(sk); |
168 | bh_unlock_sock(sk); |
169 | } |
170 | |