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1da177e4 LT |
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> | |
c752f073 | 32 | #include <net/tcp_states.h> |
1da177e4 LT |
33 | #include <asm/uaccess.h> |
34 | #include <asm/system.h> | |
35 | #include <linux/fcntl.h> | |
36 | #include <linux/mm.h> | |
37 | #include <linux/interrupt.h> | |
38 | ||
39 | /* | |
40 | * State machine for state 1, Awaiting Connection State. | |
41 | * The handling of the timer(s) is in file ax25_std_timer.c. | |
42 | * Handling of state 0 and connection release is in ax25.c. | |
43 | */ | |
44 | static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type) | |
45 | { | |
46 | switch (frametype) { | |
47 | case AX25_SABM: | |
48 | ax25->modulus = AX25_MODULUS; | |
49 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW]; | |
50 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
51 | break; | |
52 | ||
53 | case AX25_SABME: | |
54 | ax25->modulus = AX25_EMODULUS; | |
55 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW]; | |
56 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
57 | break; | |
58 | ||
59 | case AX25_DISC: | |
60 | ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE); | |
61 | break; | |
62 | ||
63 | case AX25_UA: | |
64 | if (pf) { | |
65 | ax25_calculate_rtt(ax25); | |
66 | ax25_stop_t1timer(ax25); | |
67 | ax25_start_t3timer(ax25); | |
68 | ax25_start_idletimer(ax25); | |
69 | ax25->vs = 0; | |
70 | ax25->va = 0; | |
71 | ax25->vr = 0; | |
72 | ax25->state = AX25_STATE_3; | |
73 | ax25->n2count = 0; | |
74 | if (ax25->sk != NULL) { | |
75 | bh_lock_sock(ax25->sk); | |
76 | ax25->sk->sk_state = TCP_ESTABLISHED; | |
77 | /* For WAIT_SABM connections we will produce an accept ready socket here */ | |
78 | if (!sock_flag(ax25->sk, SOCK_DEAD)) | |
79 | ax25->sk->sk_state_change(ax25->sk); | |
80 | bh_unlock_sock(ax25->sk); | |
81 | } | |
82 | } | |
83 | break; | |
84 | ||
85 | case AX25_DM: | |
86 | if (pf) { | |
87 | if (ax25->modulus == AX25_MODULUS) { | |
88 | ax25_disconnect(ax25, ECONNREFUSED); | |
89 | } else { | |
90 | ax25->modulus = AX25_MODULUS; | |
91 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW]; | |
92 | } | |
93 | } | |
94 | break; | |
95 | ||
96 | default: | |
97 | break; | |
98 | } | |
99 | ||
100 | return 0; | |
101 | } | |
102 | ||
103 | /* | |
104 | * State machine for state 2, Awaiting Release State. | |
105 | * The handling of the timer(s) is in file ax25_std_timer.c | |
106 | * Handling of state 0 and connection release is in ax25.c. | |
107 | */ | |
108 | static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type) | |
109 | { | |
110 | switch (frametype) { | |
111 | case AX25_SABM: | |
112 | case AX25_SABME: | |
113 | ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE); | |
114 | break; | |
115 | ||
116 | case AX25_DISC: | |
117 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
118 | ax25_disconnect(ax25, 0); | |
119 | break; | |
120 | ||
121 | case AX25_DM: | |
122 | case AX25_UA: | |
123 | if (pf) | |
124 | ax25_disconnect(ax25, 0); | |
125 | break; | |
126 | ||
127 | case AX25_I: | |
128 | case AX25_REJ: | |
129 | case AX25_RNR: | |
130 | case AX25_RR: | |
131 | if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE); | |
132 | break; | |
133 | ||
134 | default: | |
135 | break; | |
136 | } | |
137 | ||
138 | return 0; | |
139 | } | |
140 | ||
141 | /* | |
142 | * State machine for state 3, Connected State. | |
143 | * The handling of the timer(s) is in file ax25_std_timer.c | |
144 | * Handling of state 0 and connection release is in ax25.c. | |
145 | */ | |
146 | static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type) | |
147 | { | |
148 | int queued = 0; | |
149 | ||
150 | switch (frametype) { | |
151 | case AX25_SABM: | |
152 | case AX25_SABME: | |
153 | if (frametype == AX25_SABM) { | |
154 | ax25->modulus = AX25_MODULUS; | |
155 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW]; | |
156 | } else { | |
157 | ax25->modulus = AX25_EMODULUS; | |
158 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW]; | |
159 | } | |
160 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
161 | ax25_stop_t1timer(ax25); | |
162 | ax25_stop_t2timer(ax25); | |
163 | ax25_start_t3timer(ax25); | |
164 | ax25_start_idletimer(ax25); | |
165 | ax25->condition = 0x00; | |
166 | ax25->vs = 0; | |
167 | ax25->va = 0; | |
168 | ax25->vr = 0; | |
169 | ax25_requeue_frames(ax25); | |
170 | break; | |
171 | ||
172 | case AX25_DISC: | |
173 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
174 | ax25_disconnect(ax25, 0); | |
175 | break; | |
176 | ||
177 | case AX25_DM: | |
178 | ax25_disconnect(ax25, ECONNRESET); | |
179 | break; | |
180 | ||
181 | case AX25_RR: | |
182 | case AX25_RNR: | |
183 | if (frametype == AX25_RR) | |
184 | ax25->condition &= ~AX25_COND_PEER_RX_BUSY; | |
185 | else | |
186 | ax25->condition |= AX25_COND_PEER_RX_BUSY; | |
187 | if (type == AX25_COMMAND && pf) | |
188 | ax25_std_enquiry_response(ax25); | |
189 | if (ax25_validate_nr(ax25, nr)) { | |
190 | ax25_check_iframes_acked(ax25, nr); | |
191 | } else { | |
192 | ax25_std_nr_error_recovery(ax25); | |
193 | ax25->state = AX25_STATE_1; | |
194 | } | |
195 | break; | |
196 | ||
197 | case AX25_REJ: | |
198 | ax25->condition &= ~AX25_COND_PEER_RX_BUSY; | |
199 | if (type == AX25_COMMAND && pf) | |
200 | ax25_std_enquiry_response(ax25); | |
201 | if (ax25_validate_nr(ax25, nr)) { | |
202 | ax25_frames_acked(ax25, nr); | |
203 | ax25_calculate_rtt(ax25); | |
204 | ax25_stop_t1timer(ax25); | |
205 | ax25_start_t3timer(ax25); | |
206 | ax25_requeue_frames(ax25); | |
207 | } else { | |
208 | ax25_std_nr_error_recovery(ax25); | |
209 | ax25->state = AX25_STATE_1; | |
210 | } | |
211 | break; | |
212 | ||
213 | case AX25_I: | |
214 | if (!ax25_validate_nr(ax25, nr)) { | |
215 | ax25_std_nr_error_recovery(ax25); | |
216 | ax25->state = AX25_STATE_1; | |
217 | break; | |
218 | } | |
219 | if (ax25->condition & AX25_COND_PEER_RX_BUSY) { | |
220 | ax25_frames_acked(ax25, nr); | |
221 | } else { | |
222 | ax25_check_iframes_acked(ax25, nr); | |
223 | } | |
224 | if (ax25->condition & AX25_COND_OWN_RX_BUSY) { | |
225 | if (pf) ax25_std_enquiry_response(ax25); | |
226 | break; | |
227 | } | |
228 | if (ns == ax25->vr) { | |
229 | ax25->vr = (ax25->vr + 1) % ax25->modulus; | |
230 | queued = ax25_rx_iframe(ax25, skb); | |
231 | if (ax25->condition & AX25_COND_OWN_RX_BUSY) | |
232 | ax25->vr = ns; /* ax25->vr - 1 */ | |
233 | ax25->condition &= ~AX25_COND_REJECT; | |
234 | if (pf) { | |
235 | ax25_std_enquiry_response(ax25); | |
236 | } else { | |
237 | if (!(ax25->condition & AX25_COND_ACK_PENDING)) { | |
238 | ax25->condition |= AX25_COND_ACK_PENDING; | |
239 | ax25_start_t2timer(ax25); | |
240 | } | |
241 | } | |
242 | } else { | |
243 | if (ax25->condition & AX25_COND_REJECT) { | |
244 | if (pf) ax25_std_enquiry_response(ax25); | |
245 | } else { | |
246 | ax25->condition |= AX25_COND_REJECT; | |
247 | ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE); | |
248 | ax25->condition &= ~AX25_COND_ACK_PENDING; | |
249 | } | |
250 | } | |
251 | break; | |
252 | ||
253 | case AX25_FRMR: | |
254 | case AX25_ILLEGAL: | |
255 | ax25_std_establish_data_link(ax25); | |
256 | ax25->state = AX25_STATE_1; | |
257 | break; | |
258 | ||
259 | default: | |
260 | break; | |
261 | } | |
262 | ||
263 | return queued; | |
264 | } | |
265 | ||
266 | /* | |
267 | * State machine for state 4, Timer Recovery State. | |
268 | * The handling of the timer(s) is in file ax25_std_timer.c | |
269 | * Handling of state 0 and connection release is in ax25.c. | |
270 | */ | |
271 | static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type) | |
272 | { | |
273 | int queued = 0; | |
274 | ||
275 | switch (frametype) { | |
276 | case AX25_SABM: | |
277 | case AX25_SABME: | |
278 | if (frametype == AX25_SABM) { | |
279 | ax25->modulus = AX25_MODULUS; | |
280 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW]; | |
281 | } else { | |
282 | ax25->modulus = AX25_EMODULUS; | |
283 | ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW]; | |
284 | } | |
285 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
286 | ax25_stop_t1timer(ax25); | |
287 | ax25_stop_t2timer(ax25); | |
288 | ax25_start_t3timer(ax25); | |
289 | ax25_start_idletimer(ax25); | |
290 | ax25->condition = 0x00; | |
291 | ax25->vs = 0; | |
292 | ax25->va = 0; | |
293 | ax25->vr = 0; | |
294 | ax25->state = AX25_STATE_3; | |
295 | ax25->n2count = 0; | |
296 | ax25_requeue_frames(ax25); | |
297 | break; | |
298 | ||
299 | case AX25_DISC: | |
300 | ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE); | |
301 | ax25_disconnect(ax25, 0); | |
302 | break; | |
303 | ||
304 | case AX25_DM: | |
305 | ax25_disconnect(ax25, ECONNRESET); | |
306 | break; | |
307 | ||
308 | case AX25_RR: | |
309 | case AX25_RNR: | |
310 | if (frametype == AX25_RR) | |
311 | ax25->condition &= ~AX25_COND_PEER_RX_BUSY; | |
312 | else | |
313 | ax25->condition |= AX25_COND_PEER_RX_BUSY; | |
314 | if (type == AX25_RESPONSE && pf) { | |
315 | ax25_stop_t1timer(ax25); | |
316 | ax25->n2count = 0; | |
317 | if (ax25_validate_nr(ax25, nr)) { | |
318 | ax25_frames_acked(ax25, nr); | |
319 | if (ax25->vs == ax25->va) { | |
320 | ax25_start_t3timer(ax25); | |
321 | ax25->state = AX25_STATE_3; | |
322 | } else { | |
323 | ax25_requeue_frames(ax25); | |
324 | } | |
325 | } else { | |
326 | ax25_std_nr_error_recovery(ax25); | |
327 | ax25->state = AX25_STATE_1; | |
328 | } | |
329 | break; | |
330 | } | |
331 | if (type == AX25_COMMAND && pf) | |
332 | ax25_std_enquiry_response(ax25); | |
333 | if (ax25_validate_nr(ax25, nr)) { | |
334 | ax25_frames_acked(ax25, nr); | |
335 | } else { | |
336 | ax25_std_nr_error_recovery(ax25); | |
337 | ax25->state = AX25_STATE_1; | |
338 | } | |
339 | break; | |
340 | ||
341 | case AX25_REJ: | |
342 | ax25->condition &= ~AX25_COND_PEER_RX_BUSY; | |
343 | if (pf && type == AX25_RESPONSE) { | |
344 | ax25_stop_t1timer(ax25); | |
345 | ax25->n2count = 0; | |
346 | if (ax25_validate_nr(ax25, nr)) { | |
347 | ax25_frames_acked(ax25, nr); | |
348 | if (ax25->vs == ax25->va) { | |
349 | ax25_start_t3timer(ax25); | |
350 | ax25->state = AX25_STATE_3; | |
351 | } else { | |
352 | ax25_requeue_frames(ax25); | |
353 | } | |
354 | } else { | |
355 | ax25_std_nr_error_recovery(ax25); | |
356 | ax25->state = AX25_STATE_1; | |
357 | } | |
358 | break; | |
359 | } | |
360 | if (type == AX25_COMMAND && pf) | |
361 | ax25_std_enquiry_response(ax25); | |
362 | if (ax25_validate_nr(ax25, nr)) { | |
363 | ax25_frames_acked(ax25, nr); | |
364 | ax25_requeue_frames(ax25); | |
365 | } else { | |
366 | ax25_std_nr_error_recovery(ax25); | |
367 | ax25->state = AX25_STATE_1; | |
368 | } | |
369 | break; | |
370 | ||
371 | case AX25_I: | |
372 | if (!ax25_validate_nr(ax25, nr)) { | |
373 | ax25_std_nr_error_recovery(ax25); | |
374 | ax25->state = AX25_STATE_1; | |
375 | break; | |
376 | } | |
377 | ax25_frames_acked(ax25, nr); | |
378 | if (ax25->condition & AX25_COND_OWN_RX_BUSY) { | |
379 | if (pf) | |
380 | ax25_std_enquiry_response(ax25); | |
381 | break; | |
382 | } | |
383 | if (ns == ax25->vr) { | |
384 | ax25->vr = (ax25->vr + 1) % ax25->modulus; | |
385 | queued = ax25_rx_iframe(ax25, skb); | |
386 | if (ax25->condition & AX25_COND_OWN_RX_BUSY) | |
387 | ax25->vr = ns; /* ax25->vr - 1 */ | |
388 | ax25->condition &= ~AX25_COND_REJECT; | |
389 | if (pf) { | |
390 | ax25_std_enquiry_response(ax25); | |
391 | } else { | |
392 | if (!(ax25->condition & AX25_COND_ACK_PENDING)) { | |
393 | ax25->condition |= AX25_COND_ACK_PENDING; | |
394 | ax25_start_t2timer(ax25); | |
395 | } | |
396 | } | |
397 | } else { | |
398 | if (ax25->condition & AX25_COND_REJECT) { | |
399 | if (pf) ax25_std_enquiry_response(ax25); | |
400 | } else { | |
401 | ax25->condition |= AX25_COND_REJECT; | |
402 | ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE); | |
403 | ax25->condition &= ~AX25_COND_ACK_PENDING; | |
404 | } | |
405 | } | |
406 | break; | |
407 | ||
408 | case AX25_FRMR: | |
409 | case AX25_ILLEGAL: | |
410 | ax25_std_establish_data_link(ax25); | |
411 | ax25->state = AX25_STATE_1; | |
412 | break; | |
413 | ||
414 | default: | |
415 | break; | |
416 | } | |
417 | ||
418 | return queued; | |
419 | } | |
420 | ||
421 | /* | |
422 | * Higher level upcall for a LAPB frame | |
423 | */ | |
424 | int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type) | |
425 | { | |
426 | int queued = 0, frametype, ns, nr, pf; | |
427 | ||
428 | frametype = ax25_decode(ax25, skb, &ns, &nr, &pf); | |
429 | ||
430 | switch (ax25->state) { | |
431 | case AX25_STATE_1: | |
432 | queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type); | |
433 | break; | |
434 | case AX25_STATE_2: | |
435 | queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type); | |
436 | break; | |
437 | case AX25_STATE_3: | |
438 | queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type); | |
439 | break; | |
440 | case AX25_STATE_4: | |
441 | queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type); | |
442 | break; | |
443 | } | |
444 | ||
445 | ax25_kick(ax25); | |
446 | ||
447 | return queued; | |
448 | } |