1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
|
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
* Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
*
* Most of this code is based on the SDL diagrams published in the 7th ARRL
* Computer Networking Conference papers. The diagrams have mistakes in them,
* but are mostly correct. Before you modify the code could you read the SDL
* diagrams as the code is not obvious and probably very easy to break.
*/
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
/*
* State machine for state 1, Awaiting Connection State.
* The handling of the timer(s) is in file ax25_std_timer.c.
* Handling of state 0 and connection release is in ax25.c.
*/
static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
{
switch (frametype) {
case AX25_SABM:
ax25->modulus = AX25_MODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
break;
case AX25_SABME:
ax25->modulus = AX25_EMODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
break;
case AX25_DISC:
ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
break;
case AX25_UA:
if (pf) {
ax25_calculate_rtt(ax25);
ax25_stop_t1timer(ax25);
ax25_start_t3timer(ax25);
ax25_start_idletimer(ax25);
ax25->vs = 0;
ax25->va = 0;
ax25->vr = 0;
ax25->state = AX25_STATE_3;
ax25->n2count = 0;
if (ax25->sk != NULL) {
bh_lock_sock(ax25->sk);
ax25->sk->sk_state = TCP_ESTABLISHED;
/* For WAIT_SABM connections we will produce an accept ready socket here */
if (!sock_flag(ax25->sk, SOCK_DEAD))
ax25->sk->sk_state_change(ax25->sk);
bh_unlock_sock(ax25->sk);
}
}
break;
case AX25_DM:
if (pf) {
if (ax25->modulus == AX25_MODULUS) {
ax25_disconnect(ax25, ECONNREFUSED);
} else {
ax25->modulus = AX25_MODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
}
}
break;
default:
break;
}
return 0;
}
/*
* State machine for state 2, Awaiting Release State.
* The handling of the timer(s) is in file ax25_std_timer.c
* Handling of state 0 and connection release is in ax25.c.
*/
static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
{
switch (frametype) {
case AX25_SABM:
case AX25_SABME:
ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
break;
case AX25_DISC:
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
ax25_disconnect(ax25, 0);
break;
case AX25_DM:
case AX25_UA:
if (pf)
ax25_disconnect(ax25, 0);
break;
case AX25_I:
case AX25_REJ:
case AX25_RNR:
case AX25_RR:
if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
break;
default:
break;
}
return 0;
}
/*
* State machine for state 3, Connected State.
* The handling of the timer(s) is in file ax25_std_timer.c
* Handling of state 0 and connection release is in ax25.c.
*/
static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
{
int queued = 0;
switch (frametype) {
case AX25_SABM:
case AX25_SABME:
if (frametype == AX25_SABM) {
ax25->modulus = AX25_MODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
} else {
ax25->modulus = AX25_EMODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
}
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
ax25_stop_t1timer(ax25);
ax25_stop_t2timer(ax25);
ax25_start_t3timer(ax25);
ax25_start_idletimer(ax25);
ax25->condition = 0x00;
ax25->vs = 0;
ax25->va = 0;
ax25->vr = 0;
ax25_requeue_frames(ax25);
break;
case AX25_DISC:
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
ax25_disconnect(ax25, 0);
break;
case AX25_DM:
ax25_disconnect(ax25, ECONNRESET);
break;
case AX25_RR:
case AX25_RNR:
if (frametype == AX25_RR)
ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
else
ax25->condition |= AX25_COND_PEER_RX_BUSY;
if (type == AX25_COMMAND && pf)
ax25_std_enquiry_response(ax25);
if (ax25_validate_nr(ax25, nr)) {
ax25_check_iframes_acked(ax25, nr);
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
case AX25_REJ:
ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
if (type == AX25_COMMAND && pf)
ax25_std_enquiry_response(ax25);
if (ax25_validate_nr(ax25, nr)) {
ax25_frames_acked(ax25, nr);
ax25_calculate_rtt(ax25);
ax25_stop_t1timer(ax25);
ax25_start_t3timer(ax25);
ax25_requeue_frames(ax25);
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
case AX25_I:
if (!ax25_validate_nr(ax25, nr)) {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
break;
}
if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
ax25_frames_acked(ax25, nr);
} else {
ax25_check_iframes_acked(ax25, nr);
}
if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
if (pf) ax25_std_enquiry_response(ax25);
break;
}
if (ns == ax25->vr) {
ax25->vr = (ax25->vr + 1) % ax25->modulus;
queued = ax25_rx_iframe(ax25, skb);
if (ax25->condition & AX25_COND_OWN_RX_BUSY)
ax25->vr = ns; /* ax25->vr - 1 */
ax25->condition &= ~AX25_COND_REJECT;
if (pf) {
ax25_std_enquiry_response(ax25);
} else {
if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
ax25->condition |= AX25_COND_ACK_PENDING;
ax25_start_t2timer(ax25);
}
}
} else {
if (ax25->condition & AX25_COND_REJECT) {
if (pf) ax25_std_enquiry_response(ax25);
} else {
ax25->condition |= AX25_COND_REJECT;
ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
ax25->condition &= ~AX25_COND_ACK_PENDING;
}
}
break;
case AX25_FRMR:
case AX25_ILLEGAL:
ax25_std_establish_data_link(ax25);
ax25->state = AX25_STATE_1;
break;
default:
break;
}
return queued;
}
/*
* State machine for state 4, Timer Recovery State.
* The handling of the timer(s) is in file ax25_std_timer.c
* Handling of state 0 and connection release is in ax25.c.
*/
static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
{
int queued = 0;
switch (frametype) {
case AX25_SABM:
case AX25_SABME:
if (frametype == AX25_SABM) {
ax25->modulus = AX25_MODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
} else {
ax25->modulus = AX25_EMODULUS;
ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
}
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
ax25_stop_t1timer(ax25);
ax25_stop_t2timer(ax25);
ax25_start_t3timer(ax25);
ax25_start_idletimer(ax25);
ax25->condition = 0x00;
ax25->vs = 0;
ax25->va = 0;
ax25->vr = 0;
ax25->state = AX25_STATE_3;
ax25->n2count = 0;
ax25_requeue_frames(ax25);
break;
case AX25_DISC:
ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
ax25_disconnect(ax25, 0);
break;
case AX25_DM:
ax25_disconnect(ax25, ECONNRESET);
break;
case AX25_RR:
case AX25_RNR:
if (frametype == AX25_RR)
ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
else
ax25->condition |= AX25_COND_PEER_RX_BUSY;
if (type == AX25_RESPONSE && pf) {
ax25_stop_t1timer(ax25);
ax25->n2count = 0;
if (ax25_validate_nr(ax25, nr)) {
ax25_frames_acked(ax25, nr);
if (ax25->vs == ax25->va) {
ax25_start_t3timer(ax25);
ax25->state = AX25_STATE_3;
} else {
ax25_requeue_frames(ax25);
}
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
}
if (type == AX25_COMMAND && pf)
ax25_std_enquiry_response(ax25);
if (ax25_validate_nr(ax25, nr)) {
ax25_frames_acked(ax25, nr);
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
case AX25_REJ:
ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
if (pf && type == AX25_RESPONSE) {
ax25_stop_t1timer(ax25);
ax25->n2count = 0;
if (ax25_validate_nr(ax25, nr)) {
ax25_frames_acked(ax25, nr);
if (ax25->vs == ax25->va) {
ax25_start_t3timer(ax25);
ax25->state = AX25_STATE_3;
} else {
ax25_requeue_frames(ax25);
}
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
}
if (type == AX25_COMMAND && pf)
ax25_std_enquiry_response(ax25);
if (ax25_validate_nr(ax25, nr)) {
ax25_frames_acked(ax25, nr);
ax25_requeue_frames(ax25);
} else {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
}
break;
case AX25_I:
if (!ax25_validate_nr(ax25, nr)) {
ax25_std_nr_error_recovery(ax25);
ax25->state = AX25_STATE_1;
break;
}
ax25_frames_acked(ax25, nr);
if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
if (pf)
ax25_std_enquiry_response(ax25);
break;
}
if (ns == ax25->vr) {
ax25->vr = (ax25->vr + 1) % ax25->modulus;
queued = ax25_rx_iframe(ax25, skb);
if (ax25->condition & AX25_COND_OWN_RX_BUSY)
ax25->vr = ns; /* ax25->vr - 1 */
ax25->condition &= ~AX25_COND_REJECT;
if (pf) {
ax25_std_enquiry_response(ax25);
} else {
if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
ax25->condition |= AX25_COND_ACK_PENDING;
ax25_start_t2timer(ax25);
}
}
} else {
if (ax25->condition & AX25_COND_REJECT) {
if (pf) ax25_std_enquiry_response(ax25);
} else {
ax25->condition |= AX25_COND_REJECT;
ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
ax25->condition &= ~AX25_COND_ACK_PENDING;
}
}
break;
case AX25_FRMR:
case AX25_ILLEGAL:
ax25_std_establish_data_link(ax25);
ax25->state = AX25_STATE_1;
break;
default:
break;
}
return queued;
}
/*
* Higher level upcall for a LAPB frame
*/
int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
{
int queued = 0, frametype, ns, nr, pf;
frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
switch (ax25->state) {
case AX25_STATE_1:
queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
break;
case AX25_STATE_2:
queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
break;
case AX25_STATE_3:
queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
break;
case AX25_STATE_4:
queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);
break;
}
ax25_kick(ax25);
return queued;
}
|
