xref: /openbmc/linux/net/rose/rose_in.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8  *
9  * Most of this code is based on the SDL diagrams published in the 7th ARRL
10  * Computer Networking Conference papers. The diagrams have mistakes in them,
11  * but are mostly correct. Before you modify the code could you read the SDL
12  * diagrams as the code is not obvious and probably very easy to break.
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/sched.h>
20 #include <linux/timer.h>
21 #include <linux/string.h>
22 #include <linux/sockios.h>
23 #include <linux/net.h>
24 #include <net/ax25.h>
25 #include <linux/inet.h>
26 #include <linux/netdevice.h>
27 #include <linux/skbuff.h>
28 #include <net/sock.h>
29 #include <net/tcp_states.h>
30 #include <asm/system.h>
31 #include <linux/fcntl.h>
32 #include <linux/mm.h>
33 #include <linux/interrupt.h>
34 #include <net/rose.h>
35 
36 /*
37  * State machine for state 1, Awaiting Call Accepted State.
38  * The handling of the timer(s) is in file rose_timer.c.
39  * Handling of state 0 and connection release is in af_rose.c.
40  */
41 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
42 {
43 	struct rose_sock *rose = rose_sk(sk);
44 
45 	switch (frametype) {
46 	case ROSE_CALL_ACCEPTED:
47 		rose_stop_timer(sk);
48 		rose_start_idletimer(sk);
49 		rose->condition = 0x00;
50 		rose->vs        = 0;
51 		rose->va        = 0;
52 		rose->vr        = 0;
53 		rose->vl        = 0;
54 		rose->state     = ROSE_STATE_3;
55 		sk->sk_state	= TCP_ESTABLISHED;
56 		if (!sock_flag(sk, SOCK_DEAD))
57 			sk->sk_state_change(sk);
58 		break;
59 
60 	case ROSE_CLEAR_REQUEST:
61 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
62 		rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
63 		rose->neighbour->use--;
64 		break;
65 
66 	default:
67 		break;
68 	}
69 
70 	return 0;
71 }
72 
73 /*
74  * State machine for state 2, Awaiting Clear Confirmation State.
75  * The handling of the timer(s) is in file rose_timer.c
76  * Handling of state 0 and connection release is in af_rose.c.
77  */
78 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
79 {
80 	struct rose_sock *rose = rose_sk(sk);
81 
82 	switch (frametype) {
83 	case ROSE_CLEAR_REQUEST:
84 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
85 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
86 		rose->neighbour->use--;
87 		break;
88 
89 	case ROSE_CLEAR_CONFIRMATION:
90 		rose_disconnect(sk, 0, -1, -1);
91 		rose->neighbour->use--;
92 		break;
93 
94 	default:
95 		break;
96 	}
97 
98 	return 0;
99 }
100 
101 /*
102  * State machine for state 3, Connected State.
103  * The handling of the timer(s) is in file rose_timer.c
104  * Handling of state 0 and connection release is in af_rose.c.
105  */
106 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
107 {
108 	struct rose_sock *rose = rose_sk(sk);
109 	int queued = 0;
110 
111 	switch (frametype) {
112 	case ROSE_RESET_REQUEST:
113 		rose_stop_timer(sk);
114 		rose_start_idletimer(sk);
115 		rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
116 		rose->condition = 0x00;
117 		rose->vs        = 0;
118 		rose->vr        = 0;
119 		rose->va        = 0;
120 		rose->vl        = 0;
121 		rose_requeue_frames(sk);
122 		break;
123 
124 	case ROSE_CLEAR_REQUEST:
125 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
126 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
127 		rose->neighbour->use--;
128 		break;
129 
130 	case ROSE_RR:
131 	case ROSE_RNR:
132 		if (!rose_validate_nr(sk, nr)) {
133 			rose_write_internal(sk, ROSE_RESET_REQUEST);
134 			rose->condition = 0x00;
135 			rose->vs        = 0;
136 			rose->vr        = 0;
137 			rose->va        = 0;
138 			rose->vl        = 0;
139 			rose->state     = ROSE_STATE_4;
140 			rose_start_t2timer(sk);
141 			rose_stop_idletimer(sk);
142 		} else {
143 			rose_frames_acked(sk, nr);
144 			if (frametype == ROSE_RNR) {
145 				rose->condition |= ROSE_COND_PEER_RX_BUSY;
146 			} else {
147 				rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
148 			}
149 		}
150 		break;
151 
152 	case ROSE_DATA:	/* XXX */
153 		rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
154 		if (!rose_validate_nr(sk, nr)) {
155 			rose_write_internal(sk, ROSE_RESET_REQUEST);
156 			rose->condition = 0x00;
157 			rose->vs        = 0;
158 			rose->vr        = 0;
159 			rose->va        = 0;
160 			rose->vl        = 0;
161 			rose->state     = ROSE_STATE_4;
162 			rose_start_t2timer(sk);
163 			rose_stop_idletimer(sk);
164 			break;
165 		}
166 		rose_frames_acked(sk, nr);
167 		if (ns == rose->vr) {
168 			rose_start_idletimer(sk);
169 			if (sock_queue_rcv_skb(sk, skb) == 0) {
170 				rose->vr = (rose->vr + 1) % ROSE_MODULUS;
171 				queued = 1;
172 			} else {
173 				/* Should never happen ! */
174 				rose_write_internal(sk, ROSE_RESET_REQUEST);
175 				rose->condition = 0x00;
176 				rose->vs        = 0;
177 				rose->vr        = 0;
178 				rose->va        = 0;
179 				rose->vl        = 0;
180 				rose->state     = ROSE_STATE_4;
181 				rose_start_t2timer(sk);
182 				rose_stop_idletimer(sk);
183 				break;
184 			}
185 			if (atomic_read(&sk->sk_rmem_alloc) >
186 			    (sk->sk_rcvbuf / 2))
187 				rose->condition |= ROSE_COND_OWN_RX_BUSY;
188 		}
189 		/*
190 		 * If the window is full, ack the frame, else start the
191 		 * acknowledge hold back timer.
192 		 */
193 		if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
194 			rose->condition &= ~ROSE_COND_ACK_PENDING;
195 			rose_stop_timer(sk);
196 			rose_enquiry_response(sk);
197 		} else {
198 			rose->condition |= ROSE_COND_ACK_PENDING;
199 			rose_start_hbtimer(sk);
200 		}
201 		break;
202 
203 	default:
204 		printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
205 		break;
206 	}
207 
208 	return queued;
209 }
210 
211 /*
212  * State machine for state 4, Awaiting Reset Confirmation State.
213  * The handling of the timer(s) is in file rose_timer.c
214  * Handling of state 0 and connection release is in af_rose.c.
215  */
216 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
217 {
218 	struct rose_sock *rose = rose_sk(sk);
219 
220 	switch (frametype) {
221 	case ROSE_RESET_REQUEST:
222 		rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
223 	case ROSE_RESET_CONFIRMATION:
224 		rose_stop_timer(sk);
225 		rose_start_idletimer(sk);
226 		rose->condition = 0x00;
227 		rose->va        = 0;
228 		rose->vr        = 0;
229 		rose->vs        = 0;
230 		rose->vl        = 0;
231 		rose->state     = ROSE_STATE_3;
232 		rose_requeue_frames(sk);
233 		break;
234 
235 	case ROSE_CLEAR_REQUEST:
236 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
237 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
238 		rose->neighbour->use--;
239 		break;
240 
241 	default:
242 		break;
243 	}
244 
245 	return 0;
246 }
247 
248 /*
249  * State machine for state 5, Awaiting Call Acceptance State.
250  * The handling of the timer(s) is in file rose_timer.c
251  * Handling of state 0 and connection release is in af_rose.c.
252  */
253 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
254 {
255 	if (frametype == ROSE_CLEAR_REQUEST) {
256 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
257 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
258 		rose_sk(sk)->neighbour->use--;
259 	}
260 
261 	return 0;
262 }
263 
264 /* Higher level upcall for a LAPB frame */
265 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
266 {
267 	struct rose_sock *rose = rose_sk(sk);
268 	int queued = 0, frametype, ns, nr, q, d, m;
269 
270 	if (rose->state == ROSE_STATE_0)
271 		return 0;
272 
273 	frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
274 
275 	switch (rose->state) {
276 	case ROSE_STATE_1:
277 		queued = rose_state1_machine(sk, skb, frametype);
278 		break;
279 	case ROSE_STATE_2:
280 		queued = rose_state2_machine(sk, skb, frametype);
281 		break;
282 	case ROSE_STATE_3:
283 		queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
284 		break;
285 	case ROSE_STATE_4:
286 		queued = rose_state4_machine(sk, skb, frametype);
287 		break;
288 	case ROSE_STATE_5:
289 		queued = rose_state5_machine(sk, skb, frametype);
290 		break;
291 	}
292 
293 	rose_kick(sk);
294 
295 	return queued;
296 }
297