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) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
8  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
9  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
10  * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
11  */
12 #include <linux/errno.h>
13 #include <linux/types.h>
14 #include <linux/socket.h>
15 #include <linux/in.h>
16 #include <linux/kernel.h>
17 #include <linux/timer.h>
18 #include <linux/string.h>
19 #include <linux/sockios.h>
20 #include <linux/net.h>
21 #include <net/ax25.h>
22 #include <linux/inet.h>
23 #include <linux/netdevice.h>
24 #include <linux/skbuff.h>
25 #include <net/sock.h>
26 #include <net/tcp_states.h>
27 #include <asm/uaccess.h>
28 #include <linux/fcntl.h>
29 #include <linux/mm.h>
30 #include <linux/interrupt.h>
31 
ax25_std_heartbeat_expiry(ax25_cb * ax25)32 void ax25_std_heartbeat_expiry(ax25_cb *ax25)
33 {
34 	struct sock *sk = ax25->sk;
35 
36 	if (sk)
37 		bh_lock_sock(sk);
38 
39 	switch (ax25->state) {
40 	case AX25_STATE_0:
41 		/* Magic here: If we listen() and a new link dies before it
42 		   is accepted() it isn't 'dead' so doesn't get removed. */
43 		if (!sk || sock_flag(sk, SOCK_DESTROY) ||
44 		    (sk->sk_state == TCP_LISTEN &&
45 		     sock_flag(sk, SOCK_DEAD))) {
46 			if (sk) {
47 				sock_hold(sk);
48 				ax25_destroy_socket(ax25);
49 				bh_unlock_sock(sk);
50 				sock_put(sk);
51 			} else
52 				ax25_destroy_socket(ax25);
53 			return;
54 		}
55 		break;
56 
57 	case AX25_STATE_3:
58 	case AX25_STATE_4:
59 		/*
60 		 * Check the state of the receive buffer.
61 		 */
62 		if (sk != NULL) {
63 			if (atomic_read(&sk->sk_rmem_alloc) <
64 			    (sk->sk_rcvbuf >> 1) &&
65 			    (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
66 				ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
67 				ax25->condition &= ~AX25_COND_ACK_PENDING;
68 				ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE);
69 				break;
70 			}
71 		}
72 	}
73 
74 	if (sk)
75 		bh_unlock_sock(sk);
76 
77 	ax25_start_heartbeat(ax25);
78 }
79 
ax25_std_t2timer_expiry(ax25_cb * ax25)80 void ax25_std_t2timer_expiry(ax25_cb *ax25)
81 {
82 	if (ax25->condition & AX25_COND_ACK_PENDING) {
83 		ax25->condition &= ~AX25_COND_ACK_PENDING;
84 		ax25_std_timeout_response(ax25);
85 	}
86 }
87 
ax25_std_t3timer_expiry(ax25_cb * ax25)88 void ax25_std_t3timer_expiry(ax25_cb *ax25)
89 {
90 	ax25->n2count = 0;
91 	ax25_std_transmit_enquiry(ax25);
92 	ax25->state   = AX25_STATE_4;
93 }
94 
ax25_std_idletimer_expiry(ax25_cb * ax25)95 void ax25_std_idletimer_expiry(ax25_cb *ax25)
96 {
97 	ax25_clear_queues(ax25);
98 
99 	ax25->n2count = 0;
100 	ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
101 	ax25->state   = AX25_STATE_2;
102 
103 	ax25_calculate_t1(ax25);
104 	ax25_start_t1timer(ax25);
105 	ax25_stop_t2timer(ax25);
106 	ax25_stop_t3timer(ax25);
107 
108 	if (ax25->sk != NULL) {
109 		bh_lock_sock(ax25->sk);
110 		ax25->sk->sk_state     = TCP_CLOSE;
111 		ax25->sk->sk_err       = 0;
112 		ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
113 		if (!sock_flag(ax25->sk, SOCK_DEAD)) {
114 			ax25->sk->sk_state_change(ax25->sk);
115 			sock_set_flag(ax25->sk, SOCK_DEAD);
116 		}
117 		bh_unlock_sock(ax25->sk);
118 	}
119 }
120 
ax25_std_t1timer_expiry(ax25_cb * ax25)121 void ax25_std_t1timer_expiry(ax25_cb *ax25)
122 {
123 	switch (ax25->state) {
124 	case AX25_STATE_1:
125 		if (ax25->n2count == ax25->n2) {
126 			if (ax25->modulus == AX25_MODULUS) {
127 				ax25_disconnect(ax25, ETIMEDOUT);
128 				return;
129 			} else {
130 				ax25->modulus = AX25_MODULUS;
131 				ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
132 				ax25->n2count = 0;
133 				ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
134 			}
135 		} else {
136 			ax25->n2count++;
137 			if (ax25->modulus == AX25_MODULUS)
138 				ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
139 			else
140 				ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND);
141 		}
142 		break;
143 
144 	case AX25_STATE_2:
145 		if (ax25->n2count == ax25->n2) {
146 			ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
147 			ax25_disconnect(ax25, ETIMEDOUT);
148 			return;
149 		} else {
150 			ax25->n2count++;
151 			ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
152 		}
153 		break;
154 
155 	case AX25_STATE_3:
156 		ax25->n2count = 1;
157 		ax25_std_transmit_enquiry(ax25);
158 		ax25->state   = AX25_STATE_4;
159 		break;
160 
161 	case AX25_STATE_4:
162 		if (ax25->n2count == ax25->n2) {
163 			ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
164 			ax25_disconnect(ax25, ETIMEDOUT);
165 			return;
166 		} else {
167 			ax25->n2count++;
168 			ax25_std_transmit_enquiry(ax25);
169 		}
170 		break;
171 	}
172 
173 	ax25_calculate_t1(ax25);
174 	ax25_start_t1timer(ax25);
175 }
176