1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *
4  * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
5  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
6  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
7  * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
8  */
9 #include <linux/errno.h>
10 #include <linux/types.h>
11 #include <linux/socket.h>
12 #include <linux/in.h>
13 #include <linux/kernel.h>
14 #include <linux/timer.h>
15 #include <linux/string.h>
16 #include <linux/sockios.h>
17 #include <linux/net.h>
18 #include <net/ax25.h>
19 #include <linux/inet.h>
20 #include <linux/netdevice.h>
21 #include <linux/skbuff.h>
22 #include <net/sock.h>
23 #include <net/tcp_states.h>
24 #include <linux/uaccess.h>
25 #include <linux/fcntl.h>
26 #include <linux/mm.h>
27 #include <linux/interrupt.h>
28 
ax25_std_heartbeat_expiry(ax25_cb * ax25)29 void ax25_std_heartbeat_expiry(ax25_cb *ax25)
30 {
31 	struct sock *sk = ax25->sk;
32 
33 	if (sk)
34 		bh_lock_sock(sk);
35 
36 	switch (ax25->state) {
37 	case AX25_STATE_0:
38 	case AX25_STATE_2:
39 		/* Magic here: If we listen() and a new link dies before it
40 		   is accepted() it isn't 'dead' so doesn't get removed. */
41 		if (!sk || sock_flag(sk, SOCK_DESTROY) ||
42 		    (sk->sk_state == TCP_LISTEN &&
43 		     sock_flag(sk, SOCK_DEAD))) {
44 			if (sk) {
45 				sock_hold(sk);
46 				ax25_destroy_socket(ax25);
47 				bh_unlock_sock(sk);
48 				/* Ungrab socket and destroy it */
49 				sock_put(sk);
50 			} else
51 				ax25_destroy_socket(ax25);
52 			return;
53 		}
54 		break;
55 
56 	case AX25_STATE_3:
57 	case AX25_STATE_4:
58 		/*
59 		 * Check the state of the receive buffer.
60 		 */
61 		if (sk != NULL) {
62 			if (atomic_read(&sk->sk_rmem_alloc) <
63 			    (sk->sk_rcvbuf >> 1) &&
64 			    (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
65 				ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
66 				ax25->condition &= ~AX25_COND_ACK_PENDING;
67 				ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE);
68 				break;
69 			}
70 		}
71 	}
72 
73 	if (sk)
74 		bh_unlock_sock(sk);
75 
76 	ax25_start_heartbeat(ax25);
77 }
78 
ax25_std_t2timer_expiry(ax25_cb * ax25)79 void ax25_std_t2timer_expiry(ax25_cb *ax25)
80 {
81 	if (ax25->condition & AX25_COND_ACK_PENDING) {
82 		ax25->condition &= ~AX25_COND_ACK_PENDING;
83 		ax25_std_timeout_response(ax25);
84 	}
85 }
86 
ax25_std_t3timer_expiry(ax25_cb * ax25)87 void ax25_std_t3timer_expiry(ax25_cb *ax25)
88 {
89 	ax25->n2count = 0;
90 	ax25_std_transmit_enquiry(ax25);
91 	ax25->state   = AX25_STATE_4;
92 }
93 
ax25_std_idletimer_expiry(ax25_cb * ax25)94 void ax25_std_idletimer_expiry(ax25_cb *ax25)
95 {
96 	ax25_clear_queues(ax25);
97 
98 	ax25->n2count = 0;
99 	ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
100 	ax25->state   = AX25_STATE_2;
101 
102 	ax25_calculate_t1(ax25);
103 	ax25_start_t1timer(ax25);
104 	ax25_stop_t2timer(ax25);
105 	ax25_stop_t3timer(ax25);
106 
107 	if (ax25->sk != NULL) {
108 		bh_lock_sock(ax25->sk);
109 		ax25->sk->sk_state     = TCP_CLOSE;
110 		ax25->sk->sk_err       = 0;
111 		ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
112 		if (!sock_flag(ax25->sk, SOCK_DEAD)) {
113 			ax25->sk->sk_state_change(ax25->sk);
114 			sock_set_flag(ax25->sk, SOCK_DEAD);
115 		}
116 		bh_unlock_sock(ax25->sk);
117 	}
118 }
119 
ax25_std_t1timer_expiry(ax25_cb * ax25)120 void ax25_std_t1timer_expiry(ax25_cb *ax25)
121 {
122 	switch (ax25->state) {
123 	case AX25_STATE_1:
124 		if (ax25->n2count == ax25->n2) {
125 			if (ax25->modulus == AX25_MODULUS) {
126 				ax25_disconnect(ax25, ETIMEDOUT);
127 				return;
128 			} else {
129 				ax25->modulus = AX25_MODULUS;
130 				ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
131 				ax25->n2count = 0;
132 				ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
133 			}
134 		} else {
135 			ax25->n2count++;
136 			if (ax25->modulus == AX25_MODULUS)
137 				ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
138 			else
139 				ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND);
140 		}
141 		break;
142 
143 	case AX25_STATE_2:
144 		if (ax25->n2count == ax25->n2) {
145 			ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
146 			if (!sock_flag(ax25->sk, SOCK_DESTROY))
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