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/timer.h>
20 #include <linux/string.h>
21 #include <linux/sockios.h>
22 #include <linux/net.h>
23 #include <net/ax25.h>
24 #include <linux/inet.h>
25 #include <linux/netdevice.h>
26 #include <linux/skbuff.h>
27 #include <net/sock.h>
28 #include <net/tcp_states.h>
29 #include <asm/system.h>
30 #include <linux/fcntl.h>
31 #include <linux/mm.h>
32 #include <linux/interrupt.h>
33 #include <net/rose.h>
34
35 /*
36 * State machine for state 1, Awaiting Call Accepted State.
37 * The handling of the timer(s) is in file rose_timer.c.
38 * Handling of state 0 and connection release is in af_rose.c.
39 */
rose_state1_machine(struct sock * sk,struct sk_buff * skb,int frametype)40 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
41 {
42 struct rose_sock *rose = rose_sk(sk);
43
44 switch (frametype) {
45 case ROSE_CALL_ACCEPTED:
46 rose_stop_timer(sk);
47 rose_start_idletimer(sk);
48 rose->condition = 0x00;
49 rose->vs = 0;
50 rose->va = 0;
51 rose->vr = 0;
52 rose->vl = 0;
53 rose->state = ROSE_STATE_3;
54 sk->sk_state = TCP_ESTABLISHED;
55 if (!sock_flag(sk, SOCK_DEAD))
56 sk->sk_state_change(sk);
57 break;
58
59 case ROSE_CLEAR_REQUEST:
60 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
61 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
62 rose->neighbour->use--;
63 break;
64
65 default:
66 break;
67 }
68
69 return 0;
70 }
71
72 /*
73 * State machine for state 2, Awaiting Clear Confirmation State.
74 * The handling of the timer(s) is in file rose_timer.c
75 * Handling of state 0 and connection release is in af_rose.c.
76 */
rose_state2_machine(struct sock * sk,struct sk_buff * skb,int frametype)77 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
78 {
79 struct rose_sock *rose = rose_sk(sk);
80
81 switch (frametype) {
82 case ROSE_CLEAR_REQUEST:
83 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
84 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
85 rose->neighbour->use--;
86 break;
87
88 case ROSE_CLEAR_CONFIRMATION:
89 rose_disconnect(sk, 0, -1, -1);
90 rose->neighbour->use--;
91 break;
92
93 default:
94 break;
95 }
96
97 return 0;
98 }
99
100 /*
101 * State machine for state 3, Connected State.
102 * The handling of the timer(s) is in file rose_timer.c
103 * Handling of state 0 and connection release is in af_rose.c.
104 */
rose_state3_machine(struct sock * sk,struct sk_buff * skb,int frametype,int ns,int nr,int q,int d,int m)105 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
106 {
107 struct rose_sock *rose = rose_sk(sk);
108 int queued = 0;
109
110 switch (frametype) {
111 case ROSE_RESET_REQUEST:
112 rose_stop_timer(sk);
113 rose_start_idletimer(sk);
114 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
115 rose->condition = 0x00;
116 rose->vs = 0;
117 rose->vr = 0;
118 rose->va = 0;
119 rose->vl = 0;
120 rose_requeue_frames(sk);
121 break;
122
123 case ROSE_CLEAR_REQUEST:
124 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
125 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
126 rose->neighbour->use--;
127 break;
128
129 case ROSE_RR:
130 case ROSE_RNR:
131 if (!rose_validate_nr(sk, nr)) {
132 rose_write_internal(sk, ROSE_RESET_REQUEST);
133 rose->condition = 0x00;
134 rose->vs = 0;
135 rose->vr = 0;
136 rose->va = 0;
137 rose->vl = 0;
138 rose->state = ROSE_STATE_4;
139 rose_start_t2timer(sk);
140 rose_stop_idletimer(sk);
141 } else {
142 rose_frames_acked(sk, nr);
143 if (frametype == ROSE_RNR) {
144 rose->condition |= ROSE_COND_PEER_RX_BUSY;
145 } else {
146 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
147 }
148 }
149 break;
150
151 case ROSE_DATA: /* XXX */
152 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
153 if (!rose_validate_nr(sk, nr)) {
154 rose_write_internal(sk, ROSE_RESET_REQUEST);
155 rose->condition = 0x00;
156 rose->vs = 0;
157 rose->vr = 0;
158 rose->va = 0;
159 rose->vl = 0;
160 rose->state = ROSE_STATE_4;
161 rose_start_t2timer(sk);
162 rose_stop_idletimer(sk);
163 break;
164 }
165 rose_frames_acked(sk, nr);
166 if (ns == rose->vr) {
167 rose_start_idletimer(sk);
168 if (sock_queue_rcv_skb(sk, skb) == 0) {
169 rose->vr = (rose->vr + 1) % ROSE_MODULUS;
170 queued = 1;
171 } else {
172 /* Should never happen ! */
173 rose_write_internal(sk, ROSE_RESET_REQUEST);
174 rose->condition = 0x00;
175 rose->vs = 0;
176 rose->vr = 0;
177 rose->va = 0;
178 rose->vl = 0;
179 rose->state = ROSE_STATE_4;
180 rose_start_t2timer(sk);
181 rose_stop_idletimer(sk);
182 break;
183 }
184 if (atomic_read(&sk->sk_rmem_alloc) >
185 (sk->sk_rcvbuf >> 1))
186 rose->condition |= ROSE_COND_OWN_RX_BUSY;
187 }
188 /*
189 * If the window is full, ack the frame, else start the
190 * acknowledge hold back timer.
191 */
192 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
193 rose->condition &= ~ROSE_COND_ACK_PENDING;
194 rose_stop_timer(sk);
195 rose_enquiry_response(sk);
196 } else {
197 rose->condition |= ROSE_COND_ACK_PENDING;
198 rose_start_hbtimer(sk);
199 }
200 break;
201
202 default:
203 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
204 break;
205 }
206
207 return queued;
208 }
209
210 /*
211 * State machine for state 4, Awaiting Reset Confirmation State.
212 * The handling of the timer(s) is in file rose_timer.c
213 * Handling of state 0 and connection release is in af_rose.c.
214 */
rose_state4_machine(struct sock * sk,struct sk_buff * skb,int frametype)215 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
216 {
217 struct rose_sock *rose = rose_sk(sk);
218
219 switch (frametype) {
220 case ROSE_RESET_REQUEST:
221 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
222 case ROSE_RESET_CONFIRMATION:
223 rose_stop_timer(sk);
224 rose_start_idletimer(sk);
225 rose->condition = 0x00;
226 rose->va = 0;
227 rose->vr = 0;
228 rose->vs = 0;
229 rose->vl = 0;
230 rose->state = ROSE_STATE_3;
231 rose_requeue_frames(sk);
232 break;
233
234 case ROSE_CLEAR_REQUEST:
235 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
236 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
237 rose->neighbour->use--;
238 break;
239
240 default:
241 break;
242 }
243
244 return 0;
245 }
246
247 /*
248 * State machine for state 5, Awaiting Call Acceptance State.
249 * The handling of the timer(s) is in file rose_timer.c
250 * Handling of state 0 and connection release is in af_rose.c.
251 */
rose_state5_machine(struct sock * sk,struct sk_buff * skb,int frametype)252 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
253 {
254 if (frametype == ROSE_CLEAR_REQUEST) {
255 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
256 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
257 rose_sk(sk)->neighbour->use--;
258 }
259
260 return 0;
261 }
262
263 /* Higher level upcall for a LAPB frame */
rose_process_rx_frame(struct sock * sk,struct sk_buff * skb)264 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
265 {
266 struct rose_sock *rose = rose_sk(sk);
267 int queued = 0, frametype, ns, nr, q, d, m;
268
269 if (rose->state == ROSE_STATE_0)
270 return 0;
271
272 frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
273
274 switch (rose->state) {
275 case ROSE_STATE_1:
276 queued = rose_state1_machine(sk, skb, frametype);
277 break;
278 case ROSE_STATE_2:
279 queued = rose_state2_machine(sk, skb, frametype);
280 break;
281 case ROSE_STATE_3:
282 queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
283 break;
284 case ROSE_STATE_4:
285 queued = rose_state4_machine(sk, skb, frametype);
286 break;
287 case ROSE_STATE_5:
288 queued = rose_state5_machine(sk, skb, frametype);
289 break;
290 }
291
292 rose_kick(sk);
293
294 return queued;
295 }
296