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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> | |
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 | */ | |
45 | static 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 | */ | |
109 | static 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 | */ | |
147 | static 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 | */ | |
272 | static 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 | */ | |
425 | int 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 | } |