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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/ip.h> /* For ip_rcv */
30#include <net/tcp.h>
31#include <asm/system.h>
32#include <linux/fcntl.h>
33#include <linux/mm.h>
34#include <linux/interrupt.h>
35#include <net/rose.h>
36
37/*
38 * State machine for state 1, Awaiting Call Accepted State.
39 * The handling of the timer(s) is in file rose_timer.c.
40 * Handling of state 0 and connection release is in af_rose.c.
41 */
42static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
43{
44 struct rose_sock *rose = rose_sk(sk);
45
46 switch (frametype) {
47 case ROSE_CALL_ACCEPTED:
48 rose_stop_timer(sk);
49 rose_start_idletimer(sk);
50 rose->condition = 0x00;
51 rose->vs = 0;
52 rose->va = 0;
53 rose->vr = 0;
54 rose->vl = 0;
55 rose->state = ROSE_STATE_3;
56 sk->sk_state = TCP_ESTABLISHED;
57 if (!sock_flag(sk, SOCK_DEAD))
58 sk->sk_state_change(sk);
59 break;
60
61 case ROSE_CLEAR_REQUEST:
62 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
63 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
64 rose->neighbour->use--;
65 break;
66
67 default:
68 break;
69 }
70
71 return 0;
72}
73
74/*
75 * State machine for state 2, Awaiting Clear Confirmation State.
76 * The handling of the timer(s) is in file rose_timer.c
77 * Handling of state 0 and connection release is in af_rose.c.
78 */
79static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
80{
81 struct rose_sock *rose = rose_sk(sk);
82
83 switch (frametype) {
84 case ROSE_CLEAR_REQUEST:
85 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
86 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
87 rose->neighbour->use--;
88 break;
89
90 case ROSE_CLEAR_CONFIRMATION:
91 rose_disconnect(sk, 0, -1, -1);
92 rose->neighbour->use--;
93 break;
94
95 default:
96 break;
97 }
98
99 return 0;
100}
101
102/*
103 * State machine for state 3, Connected State.
104 * The handling of the timer(s) is in file rose_timer.c
105 * Handling of state 0 and connection release is in af_rose.c.
106 */
107static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
108{
109 struct rose_sock *rose = rose_sk(sk);
110 int queued = 0;
111
112 switch (frametype) {
113 case ROSE_RESET_REQUEST:
114 rose_stop_timer(sk);
115 rose_start_idletimer(sk);
116 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
117 rose->condition = 0x00;
118 rose->vs = 0;
119 rose->vr = 0;
120 rose->va = 0;
121 rose->vl = 0;
122 rose_requeue_frames(sk);
123 break;
124
125 case ROSE_CLEAR_REQUEST:
126 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
127 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
128 rose->neighbour->use--;
129 break;
130
131 case ROSE_RR:
132 case ROSE_RNR:
133 if (!rose_validate_nr(sk, nr)) {
134 rose_write_internal(sk, ROSE_RESET_REQUEST);
135 rose->condition = 0x00;
136 rose->vs = 0;
137 rose->vr = 0;
138 rose->va = 0;
139 rose->vl = 0;
140 rose->state = ROSE_STATE_4;
141 rose_start_t2timer(sk);
142 rose_stop_idletimer(sk);
143 } else {
144 rose_frames_acked(sk, nr);
145 if (frametype == ROSE_RNR) {
146 rose->condition |= ROSE_COND_PEER_RX_BUSY;
147 } else {
148 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
149 }
150 }
151 break;
152
153 case ROSE_DATA: /* XXX */
154 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
155 if (!rose_validate_nr(sk, nr)) {
156 rose_write_internal(sk, ROSE_RESET_REQUEST);
157 rose->condition = 0x00;
158 rose->vs = 0;
159 rose->vr = 0;
160 rose->va = 0;
161 rose->vl = 0;
162 rose->state = ROSE_STATE_4;
163 rose_start_t2timer(sk);
164 rose_stop_idletimer(sk);
165 break;
166 }
167 rose_frames_acked(sk, nr);
168 if (ns == rose->vr) {
169 rose_start_idletimer(sk);
170 if (sock_queue_rcv_skb(sk, skb) == 0) {
171 rose->vr = (rose->vr + 1) % ROSE_MODULUS;
172 queued = 1;
173 } else {
174 /* Should never happen ! */
175 rose_write_internal(sk, ROSE_RESET_REQUEST);
176 rose->condition = 0x00;
177 rose->vs = 0;
178 rose->vr = 0;
179 rose->va = 0;
180 rose->vl = 0;
181 rose->state = ROSE_STATE_4;
182 rose_start_t2timer(sk);
183 rose_stop_idletimer(sk);
184 break;
185 }
186 if (atomic_read(&sk->sk_rmem_alloc) >
187 (sk->sk_rcvbuf / 2))
188 rose->condition |= ROSE_COND_OWN_RX_BUSY;
189 }
190 /*
191 * If the window is full, ack the frame, else start the
192 * acknowledge hold back timer.
193 */
194 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
195 rose->condition &= ~ROSE_COND_ACK_PENDING;
196 rose_stop_timer(sk);
197 rose_enquiry_response(sk);
198 } else {
199 rose->condition |= ROSE_COND_ACK_PENDING;
200 rose_start_hbtimer(sk);
201 }
202 break;
203
204 default:
205 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
206 break;
207 }
208
209 return queued;
210}
211
212/*
213 * State machine for state 4, Awaiting Reset Confirmation State.
214 * The handling of the timer(s) is in file rose_timer.c
215 * Handling of state 0 and connection release is in af_rose.c.
216 */
217static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
218{
219 struct rose_sock *rose = rose_sk(sk);
220
221 switch (frametype) {
222 case ROSE_RESET_REQUEST:
223 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
224 case ROSE_RESET_CONFIRMATION:
225 rose_stop_timer(sk);
226 rose_start_idletimer(sk);
227 rose->condition = 0x00;
228 rose->va = 0;
229 rose->vr = 0;
230 rose->vs = 0;
231 rose->vl = 0;
232 rose->state = ROSE_STATE_3;
233 rose_requeue_frames(sk);
234 break;
235
236 case ROSE_CLEAR_REQUEST:
237 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
238 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
239 rose->neighbour->use--;
240 break;
241
242 default:
243 break;
244 }
245
246 return 0;
247}
248
249/*
250 * State machine for state 5, Awaiting Call Acceptance State.
251 * The handling of the timer(s) is in file rose_timer.c
252 * Handling of state 0 and connection release is in af_rose.c.
253 */
254static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
255{
256 if (frametype == ROSE_CLEAR_REQUEST) {
257 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
258 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
259 rose_sk(sk)->neighbour->use--;
260 }
261
262 return 0;
263}
264
265/* Higher level upcall for a LAPB frame */
266int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
267{
268 struct rose_sock *rose = rose_sk(sk);
269 int queued = 0, frametype, ns, nr, q, d, m;
270
271 if (rose->state == ROSE_STATE_0)
272 return 0;
273
274 frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
275
276 switch (rose->state) {
277 case ROSE_STATE_1:
278 queued = rose_state1_machine(sk, skb, frametype);
279 break;
280 case ROSE_STATE_2:
281 queued = rose_state2_machine(sk, skb, frametype);
282 break;
283 case ROSE_STATE_3:
284 queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
285 break;
286 case ROSE_STATE_4:
287 queued = rose_state4_machine(sk, skb, frametype);
288 break;
289 case ROSE_STATE_5:
290 queued = rose_state5_machine(sk, skb, frametype);
291 break;
292 }
293
294 rose_kick(sk);
295
296 return queued;
297}
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