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-rw-r--r--net/ax25/ax25_std_in.c449
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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) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
8 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
9 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
10 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
11 *
12 * Most of this code is based on the SDL diagrams published in the 7th ARRL
13 * Computer Networking Conference papers. The diagrams have mistakes in them,
14 * but are mostly correct. Before you modify the code could you read the SDL
15 * diagrams as the code is not obvious and probably very easy to break.
16 */
17#include <linux/errno.h>
18#include <linux/types.h>
19#include <linux/socket.h>
20#include <linux/in.h>
21#include <linux/kernel.h>
22#include <linux/sched.h>
23#include <linux/timer.h>
24#include <linux/string.h>
25#include <linux/sockios.h>
26#include <linux/net.h>
27#include <net/ax25.h>
28#include <linux/inet.h>
29#include <linux/netdevice.h>
30#include <linux/skbuff.h>
31#include <net/sock.h>
32#include <net/ip.h> /* For ip_rcv */
33#include <net/tcp.h>
34#include <asm/uaccess.h>
35#include <asm/system.h>
36#include <linux/fcntl.h>
37#include <linux/mm.h>
38#include <linux/interrupt.h>
39
40/*
41 * State machine for state 1, Awaiting Connection State.
42 * The handling of the timer(s) is in file ax25_std_timer.c.
43 * Handling of state 0 and connection release is in ax25.c.
44 */
45static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
46{
47 switch (frametype) {
48 case AX25_SABM:
49 ax25->modulus = AX25_MODULUS;
50 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
51 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
52 break;
53
54 case AX25_SABME:
55 ax25->modulus = AX25_EMODULUS;
56 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
57 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
58 break;
59
60 case AX25_DISC:
61 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
62 break;
63
64 case AX25_UA:
65 if (pf) {
66 ax25_calculate_rtt(ax25);
67 ax25_stop_t1timer(ax25);
68 ax25_start_t3timer(ax25);
69 ax25_start_idletimer(ax25);
70 ax25->vs = 0;
71 ax25->va = 0;
72 ax25->vr = 0;
73 ax25->state = AX25_STATE_3;
74 ax25->n2count = 0;
75 if (ax25->sk != NULL) {
76 bh_lock_sock(ax25->sk);
77 ax25->sk->sk_state = TCP_ESTABLISHED;
78 /* For WAIT_SABM connections we will produce an accept ready socket here */
79 if (!sock_flag(ax25->sk, SOCK_DEAD))
80 ax25->sk->sk_state_change(ax25->sk);
81 bh_unlock_sock(ax25->sk);
82 }
83 }
84 break;
85
86 case AX25_DM:
87 if (pf) {
88 if (ax25->modulus == AX25_MODULUS) {
89 ax25_disconnect(ax25, ECONNREFUSED);
90 } else {
91 ax25->modulus = AX25_MODULUS;
92 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
93 }
94 }
95 break;
96
97 default:
98 break;
99 }
100
101 return 0;
102}
103
104/*
105 * State machine for state 2, Awaiting Release State.
106 * The handling of the timer(s) is in file ax25_std_timer.c
107 * Handling of state 0 and connection release is in ax25.c.
108 */
109static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
110{
111 switch (frametype) {
112 case AX25_SABM:
113 case AX25_SABME:
114 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
115 break;
116
117 case AX25_DISC:
118 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
119 ax25_disconnect(ax25, 0);
120 break;
121
122 case AX25_DM:
123 case AX25_UA:
124 if (pf)
125 ax25_disconnect(ax25, 0);
126 break;
127
128 case AX25_I:
129 case AX25_REJ:
130 case AX25_RNR:
131 case AX25_RR:
132 if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
133 break;
134
135 default:
136 break;
137 }
138
139 return 0;
140}
141
142/*
143 * State machine for state 3, Connected State.
144 * The handling of the timer(s) is in file ax25_std_timer.c
145 * Handling of state 0 and connection release is in ax25.c.
146 */
147static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
148{
149 int queued = 0;
150
151 switch (frametype) {
152 case AX25_SABM:
153 case AX25_SABME:
154 if (frametype == AX25_SABM) {
155 ax25->modulus = AX25_MODULUS;
156 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
157 } else {
158 ax25->modulus = AX25_EMODULUS;
159 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
160 }
161 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
162 ax25_stop_t1timer(ax25);
163 ax25_stop_t2timer(ax25);
164 ax25_start_t3timer(ax25);
165 ax25_start_idletimer(ax25);
166 ax25->condition = 0x00;
167 ax25->vs = 0;
168 ax25->va = 0;
169 ax25->vr = 0;
170 ax25_requeue_frames(ax25);
171 break;
172
173 case AX25_DISC:
174 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
175 ax25_disconnect(ax25, 0);
176 break;
177
178 case AX25_DM:
179 ax25_disconnect(ax25, ECONNRESET);
180 break;
181
182 case AX25_RR:
183 case AX25_RNR:
184 if (frametype == AX25_RR)
185 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
186 else
187 ax25->condition |= AX25_COND_PEER_RX_BUSY;
188 if (type == AX25_COMMAND && pf)
189 ax25_std_enquiry_response(ax25);
190 if (ax25_validate_nr(ax25, nr)) {
191 ax25_check_iframes_acked(ax25, nr);
192 } else {
193 ax25_std_nr_error_recovery(ax25);
194 ax25->state = AX25_STATE_1;
195 }
196 break;
197
198 case AX25_REJ:
199 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
200 if (type == AX25_COMMAND && pf)
201 ax25_std_enquiry_response(ax25);
202 if (ax25_validate_nr(ax25, nr)) {
203 ax25_frames_acked(ax25, nr);
204 ax25_calculate_rtt(ax25);
205 ax25_stop_t1timer(ax25);
206 ax25_start_t3timer(ax25);
207 ax25_requeue_frames(ax25);
208 } else {
209 ax25_std_nr_error_recovery(ax25);
210 ax25->state = AX25_STATE_1;
211 }
212 break;
213
214 case AX25_I:
215 if (!ax25_validate_nr(ax25, nr)) {
216 ax25_std_nr_error_recovery(ax25);
217 ax25->state = AX25_STATE_1;
218 break;
219 }
220 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
221 ax25_frames_acked(ax25, nr);
222 } else {
223 ax25_check_iframes_acked(ax25, nr);
224 }
225 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
226 if (pf) ax25_std_enquiry_response(ax25);
227 break;
228 }
229 if (ns == ax25->vr) {
230 ax25->vr = (ax25->vr + 1) % ax25->modulus;
231 queued = ax25_rx_iframe(ax25, skb);
232 if (ax25->condition & AX25_COND_OWN_RX_BUSY)
233 ax25->vr = ns; /* ax25->vr - 1 */
234 ax25->condition &= ~AX25_COND_REJECT;
235 if (pf) {
236 ax25_std_enquiry_response(ax25);
237 } else {
238 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
239 ax25->condition |= AX25_COND_ACK_PENDING;
240 ax25_start_t2timer(ax25);
241 }
242 }
243 } else {
244 if (ax25->condition & AX25_COND_REJECT) {
245 if (pf) ax25_std_enquiry_response(ax25);
246 } else {
247 ax25->condition |= AX25_COND_REJECT;
248 ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
249 ax25->condition &= ~AX25_COND_ACK_PENDING;
250 }
251 }
252 break;
253
254 case AX25_FRMR:
255 case AX25_ILLEGAL:
256 ax25_std_establish_data_link(ax25);
257 ax25->state = AX25_STATE_1;
258 break;
259
260 default:
261 break;
262 }
263
264 return queued;
265}
266
267/*
268 * State machine for state 4, Timer Recovery State.
269 * The handling of the timer(s) is in file ax25_std_timer.c
270 * Handling of state 0 and connection release is in ax25.c.
271 */
272static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
273{
274 int queued = 0;
275
276 switch (frametype) {
277 case AX25_SABM:
278 case AX25_SABME:
279 if (frametype == AX25_SABM) {
280 ax25->modulus = AX25_MODULUS;
281 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
282 } else {
283 ax25->modulus = AX25_EMODULUS;
284 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
285 }
286 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
287 ax25_stop_t1timer(ax25);
288 ax25_stop_t2timer(ax25);
289 ax25_start_t3timer(ax25);
290 ax25_start_idletimer(ax25);
291 ax25->condition = 0x00;
292 ax25->vs = 0;
293 ax25->va = 0;
294 ax25->vr = 0;
295 ax25->state = AX25_STATE_3;
296 ax25->n2count = 0;
297 ax25_requeue_frames(ax25);
298 break;
299
300 case AX25_DISC:
301 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
302 ax25_disconnect(ax25, 0);
303 break;
304
305 case AX25_DM:
306 ax25_disconnect(ax25, ECONNRESET);
307 break;
308
309 case AX25_RR:
310 case AX25_RNR:
311 if (frametype == AX25_RR)
312 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
313 else
314 ax25->condition |= AX25_COND_PEER_RX_BUSY;
315 if (type == AX25_RESPONSE && pf) {
316 ax25_stop_t1timer(ax25);
317 ax25->n2count = 0;
318 if (ax25_validate_nr(ax25, nr)) {
319 ax25_frames_acked(ax25, nr);
320 if (ax25->vs == ax25->va) {
321 ax25_start_t3timer(ax25);
322 ax25->state = AX25_STATE_3;
323 } else {
324 ax25_requeue_frames(ax25);
325 }
326 } else {
327 ax25_std_nr_error_recovery(ax25);
328 ax25->state = AX25_STATE_1;
329 }
330 break;
331 }
332 if (type == AX25_COMMAND && pf)
333 ax25_std_enquiry_response(ax25);
334 if (ax25_validate_nr(ax25, nr)) {
335 ax25_frames_acked(ax25, nr);
336 } else {
337 ax25_std_nr_error_recovery(ax25);
338 ax25->state = AX25_STATE_1;
339 }
340 break;
341
342 case AX25_REJ:
343 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
344 if (pf && type == AX25_RESPONSE) {
345 ax25_stop_t1timer(ax25);
346 ax25->n2count = 0;
347 if (ax25_validate_nr(ax25, nr)) {
348 ax25_frames_acked(ax25, nr);
349 if (ax25->vs == ax25->va) {
350 ax25_start_t3timer(ax25);
351 ax25->state = AX25_STATE_3;
352 } else {
353 ax25_requeue_frames(ax25);
354 }
355 } else {
356 ax25_std_nr_error_recovery(ax25);
357 ax25->state = AX25_STATE_1;
358 }
359 break;
360 }
361 if (type == AX25_COMMAND && pf)
362 ax25_std_enquiry_response(ax25);
363 if (ax25_validate_nr(ax25, nr)) {
364 ax25_frames_acked(ax25, nr);
365 ax25_requeue_frames(ax25);
366 } else {
367 ax25_std_nr_error_recovery(ax25);
368 ax25->state = AX25_STATE_1;
369 }
370 break;
371
372 case AX25_I:
373 if (!ax25_validate_nr(ax25, nr)) {
374 ax25_std_nr_error_recovery(ax25);
375 ax25->state = AX25_STATE_1;
376 break;
377 }
378 ax25_frames_acked(ax25, nr);
379 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
380 if (pf)
381 ax25_std_enquiry_response(ax25);
382 break;
383 }
384 if (ns == ax25->vr) {
385 ax25->vr = (ax25->vr + 1) % ax25->modulus;
386 queued = ax25_rx_iframe(ax25, skb);
387 if (ax25->condition & AX25_COND_OWN_RX_BUSY)
388 ax25->vr = ns; /* ax25->vr - 1 */
389 ax25->condition &= ~AX25_COND_REJECT;
390 if (pf) {
391 ax25_std_enquiry_response(ax25);
392 } else {
393 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
394 ax25->condition |= AX25_COND_ACK_PENDING;
395 ax25_start_t2timer(ax25);
396 }
397 }
398 } else {
399 if (ax25->condition & AX25_COND_REJECT) {
400 if (pf) ax25_std_enquiry_response(ax25);
401 } else {
402 ax25->condition |= AX25_COND_REJECT;
403 ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
404 ax25->condition &= ~AX25_COND_ACK_PENDING;
405 }
406 }
407 break;
408
409 case AX25_FRMR:
410 case AX25_ILLEGAL:
411 ax25_std_establish_data_link(ax25);
412 ax25->state = AX25_STATE_1;
413 break;
414
415 default:
416 break;
417 }
418
419 return queued;
420}
421
422/*
423 * Higher level upcall for a LAPB frame
424 */
425int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
426{
427 int queued = 0, frametype, ns, nr, pf;
428
429 frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
430
431 switch (ax25->state) {
432 case AX25_STATE_1:
433 queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
434 break;
435 case AX25_STATE_2:
436 queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
437 break;
438 case AX25_STATE_3:
439 queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
440 break;
441 case AX25_STATE_4:
442 queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);
443 break;
444 }
445
446 ax25_kick(ax25);
447
448 return queued;
449}
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