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.
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)
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.
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/socket.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>
28 #include <linux/inet.h>
29 #include <linux/netdevice.h>
30 #include <linux/skbuff.h>
32 #include <net/ip.h> /* For ip_rcv */
34 #include <asm/uaccess.h>
35 #include <asm/system.h>
36 #include <linux/fcntl.h>
38 #include <linux/interrupt.h>
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.
45 static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
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);
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);
61 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
66 ax25_calculate_rtt(ax25);
67 ax25_stop_t1timer(ax25);
68 ax25_start_t3timer(ax25);
69 ax25_start_idletimer(ax25);
73 ax25->state = AX25_STATE_3;
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);
88 if (ax25->modulus == AX25_MODULUS) {
89 ax25_disconnect(ax25, ECONNREFUSED);
91 ax25->modulus = AX25_MODULUS;
92 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
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.
109 static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
114 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
118 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
119 ax25_disconnect(ax25, 0);
125 ax25_disconnect(ax25, 0);
132 if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
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.
147 static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
154 if (frametype == AX25_SABM) {
155 ax25->modulus = AX25_MODULUS;
156 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
158 ax25->modulus = AX25_EMODULUS;
159 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
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;
170 ax25_requeue_frames(ax25);
174 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
175 ax25_disconnect(ax25, 0);
179 ax25_disconnect(ax25, ECONNRESET);
184 if (frametype == AX25_RR)
185 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
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);
193 ax25_std_nr_error_recovery(ax25);
194 ax25->state = AX25_STATE_1;
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);
209 ax25_std_nr_error_recovery(ax25);
210 ax25->state = AX25_STATE_1;
215 if (!ax25_validate_nr(ax25, nr)) {
216 ax25_std_nr_error_recovery(ax25);
217 ax25->state = AX25_STATE_1;
220 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
221 ax25_frames_acked(ax25, nr);
223 ax25_check_iframes_acked(ax25, nr);
225 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
226 if (pf) ax25_std_enquiry_response(ax25);
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;
236 ax25_std_enquiry_response(ax25);
238 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
239 ax25->condition |= AX25_COND_ACK_PENDING;
240 ax25_start_t2timer(ax25);
244 if (ax25->condition & AX25_COND_REJECT) {
245 if (pf) ax25_std_enquiry_response(ax25);
247 ax25->condition |= AX25_COND_REJECT;
248 ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
249 ax25->condition &= ~AX25_COND_ACK_PENDING;
256 ax25_std_establish_data_link(ax25);
257 ax25->state = AX25_STATE_1;
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.
272 static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
279 if (frametype == AX25_SABM) {
280 ax25->modulus = AX25_MODULUS;
281 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
283 ax25->modulus = AX25_EMODULUS;
284 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
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;
295 ax25->state = AX25_STATE_3;
297 ax25_requeue_frames(ax25);
301 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
302 ax25_disconnect(ax25, 0);
306 ax25_disconnect(ax25, ECONNRESET);
311 if (frametype == AX25_RR)
312 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
314 ax25->condition |= AX25_COND_PEER_RX_BUSY;
315 if (type == AX25_RESPONSE && pf) {
316 ax25_stop_t1timer(ax25);
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;
324 ax25_requeue_frames(ax25);
327 ax25_std_nr_error_recovery(ax25);
328 ax25->state = AX25_STATE_1;
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);
337 ax25_std_nr_error_recovery(ax25);
338 ax25->state = AX25_STATE_1;
343 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
344 if (pf && type == AX25_RESPONSE) {
345 ax25_stop_t1timer(ax25);
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;
353 ax25_requeue_frames(ax25);
356 ax25_std_nr_error_recovery(ax25);
357 ax25->state = AX25_STATE_1;
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);
367 ax25_std_nr_error_recovery(ax25);
368 ax25->state = AX25_STATE_1;
373 if (!ax25_validate_nr(ax25, nr)) {
374 ax25_std_nr_error_recovery(ax25);
375 ax25->state = AX25_STATE_1;
378 ax25_frames_acked(ax25, nr);
379 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
381 ax25_std_enquiry_response(ax25);
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;
391 ax25_std_enquiry_response(ax25);
393 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
394 ax25->condition |= AX25_COND_ACK_PENDING;
395 ax25_start_t2timer(ax25);
399 if (ax25->condition & AX25_COND_REJECT) {
400 if (pf) ax25_std_enquiry_response(ax25);
402 ax25->condition |= AX25_COND_REJECT;
403 ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
404 ax25->condition &= ~AX25_COND_ACK_PENDING;
411 ax25_std_establish_data_link(ax25);
412 ax25->state = AX25_STATE_1;
423 * Higher level upcall for a LAPB frame
425 int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
427 int queued = 0, frametype, ns, nr, pf;
429 frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
431 switch (ax25->state) {
433 queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
436 queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
439 queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
442 queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);