1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	LAPB release 002
4  *
5  *	This code REQUIRES 2.1.15 or higher/ NET3.038
6  *
7  *	History
8  *	LAPB 001	Jonathan Naylor	Started Coding
9  *	LAPB 002	Jonathan Naylor	New timer architecture.
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/errno.h>
15 #include <linux/types.h>
16 #include <linux/socket.h>
17 #include <linux/in.h>
18 #include <linux/kernel.h>
19 #include <linux/jiffies.h>
20 #include <linux/timer.h>
21 #include <linux/string.h>
22 #include <linux/sockios.h>
23 #include <linux/net.h>
24 #include <linux/inet.h>
25 #include <linux/skbuff.h>
26 #include <net/sock.h>
27 #include <linux/uaccess.h>
28 #include <linux/fcntl.h>
29 #include <linux/mm.h>
30 #include <linux/interrupt.h>
31 #include <net/lapb.h>
32 
33 static void lapb_t1timer_expiry(struct timer_list *);
34 static void lapb_t2timer_expiry(struct timer_list *);
35 
lapb_start_t1timer(struct lapb_cb * lapb)36 void lapb_start_t1timer(struct lapb_cb *lapb)
37 {
38 	del_timer(&lapb->t1timer);
39 
40 	lapb->t1timer.function = lapb_t1timer_expiry;
41 	lapb->t1timer.expires  = jiffies + lapb->t1;
42 
43 	lapb->t1timer_running = true;
44 	add_timer(&lapb->t1timer);
45 }
46 
lapb_start_t2timer(struct lapb_cb * lapb)47 void lapb_start_t2timer(struct lapb_cb *lapb)
48 {
49 	del_timer(&lapb->t2timer);
50 
51 	lapb->t2timer.function = lapb_t2timer_expiry;
52 	lapb->t2timer.expires  = jiffies + lapb->t2;
53 
54 	lapb->t2timer_running = true;
55 	add_timer(&lapb->t2timer);
56 }
57 
lapb_stop_t1timer(struct lapb_cb * lapb)58 void lapb_stop_t1timer(struct lapb_cb *lapb)
59 {
60 	lapb->t1timer_running = false;
61 	del_timer(&lapb->t1timer);
62 }
63 
lapb_stop_t2timer(struct lapb_cb * lapb)64 void lapb_stop_t2timer(struct lapb_cb *lapb)
65 {
66 	lapb->t2timer_running = false;
67 	del_timer(&lapb->t2timer);
68 }
69 
lapb_t1timer_running(struct lapb_cb * lapb)70 int lapb_t1timer_running(struct lapb_cb *lapb)
71 {
72 	return lapb->t1timer_running;
73 }
74 
lapb_t2timer_expiry(struct timer_list * t)75 static void lapb_t2timer_expiry(struct timer_list *t)
76 {
77 	struct lapb_cb *lapb = from_timer(lapb, t, t2timer);
78 
79 	spin_lock_bh(&lapb->lock);
80 	if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */
81 		goto out;
82 	if (!lapb->t2timer_running) /* The timer has been stopped */
83 		goto out;
84 
85 	if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
86 		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
87 		lapb_timeout_response(lapb);
88 	}
89 	lapb->t2timer_running = false;
90 
91 out:
92 	spin_unlock_bh(&lapb->lock);
93 }
94 
lapb_t1timer_expiry(struct timer_list * t)95 static void lapb_t1timer_expiry(struct timer_list *t)
96 {
97 	struct lapb_cb *lapb = from_timer(lapb, t, t1timer);
98 
99 	spin_lock_bh(&lapb->lock);
100 	if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */
101 		goto out;
102 	if (!lapb->t1timer_running) /* The timer has been stopped */
103 		goto out;
104 
105 	switch (lapb->state) {
106 
107 		/*
108 		 *	If we are a DCE, send DM up to N2 times, then switch to
109 		 *	STATE_1 and send SABM(E).
110 		 */
111 		case LAPB_STATE_0:
112 			if (lapb->mode & LAPB_DCE &&
113 			    lapb->n2count != lapb->n2) {
114 				lapb->n2count++;
115 				lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
116 			} else {
117 				lapb->state = LAPB_STATE_1;
118 				lapb_establish_data_link(lapb);
119 			}
120 			break;
121 
122 		/*
123 		 *	Awaiting connection state, send SABM(E), up to N2 times.
124 		 */
125 		case LAPB_STATE_1:
126 			if (lapb->n2count == lapb->n2) {
127 				lapb_clear_queues(lapb);
128 				lapb->state = LAPB_STATE_0;
129 				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
130 				lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
131 				lapb->t1timer_running = false;
132 				goto out;
133 			} else {
134 				lapb->n2count++;
135 				if (lapb->mode & LAPB_EXTENDED) {
136 					lapb_dbg(1, "(%p) S1 TX SABME(1)\n",
137 						 lapb->dev);
138 					lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
139 				} else {
140 					lapb_dbg(1, "(%p) S1 TX SABM(1)\n",
141 						 lapb->dev);
142 					lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
143 				}
144 			}
145 			break;
146 
147 		/*
148 		 *	Awaiting disconnection state, send DISC, up to N2 times.
149 		 */
150 		case LAPB_STATE_2:
151 			if (lapb->n2count == lapb->n2) {
152 				lapb_clear_queues(lapb);
153 				lapb->state = LAPB_STATE_0;
154 				lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT);
155 				lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
156 				lapb->t1timer_running = false;
157 				goto out;
158 			} else {
159 				lapb->n2count++;
160 				lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev);
161 				lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
162 			}
163 			break;
164 
165 		/*
166 		 *	Data transfer state, restransmit I frames, up to N2 times.
167 		 */
168 		case LAPB_STATE_3:
169 			if (lapb->n2count == lapb->n2) {
170 				lapb_clear_queues(lapb);
171 				lapb->state = LAPB_STATE_0;
172 				lapb_stop_t2timer(lapb);
173 				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
174 				lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
175 				lapb->t1timer_running = false;
176 				goto out;
177 			} else {
178 				lapb->n2count++;
179 				lapb_requeue_frames(lapb);
180 				lapb_kick(lapb);
181 			}
182 			break;
183 
184 		/*
185 		 *	Frame reject state, restransmit FRMR frames, up to N2 times.
186 		 */
187 		case LAPB_STATE_4:
188 			if (lapb->n2count == lapb->n2) {
189 				lapb_clear_queues(lapb);
190 				lapb->state = LAPB_STATE_0;
191 				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
192 				lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev);
193 				lapb->t1timer_running = false;
194 				goto out;
195 			} else {
196 				lapb->n2count++;
197 				lapb_transmit_frmr(lapb);
198 			}
199 			break;
200 	}
201 
202 	lapb_start_t1timer(lapb);
203 
204 out:
205 	spin_unlock_bh(&lapb->lock);
206 }
207