/net/ax25/ax25_ds_in.c
C | 303 lines | 235 code | 34 blank | 34 comment | 45 complexity | a2fc73ad978ff3fb3df5a78612f983d2 MD5 | raw file
Possible License(s): CC-BY-SA-3.0, GPL-2.0, LGPL-2.0, AGPL-1.0
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) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
9 */
10#include <linux/errno.h>
11#include <linux/types.h>
12#include <linux/socket.h>
13#include <linux/in.h>
14#include <linux/kernel.h>
15#include <linux/timer.h>
16#include <linux/string.h>
17#include <linux/sockios.h>
18#include <linux/net.h>
19#include <net/ax25.h>
20#include <linux/inet.h>
21#include <linux/netdevice.h>
22#include <linux/skbuff.h>
23#include <net/sock.h>
24#include <net/tcp_states.h>
25#include <asm/uaccess.h>
26#include <asm/system.h>
27#include <linux/fcntl.h>
28#include <linux/mm.h>
29#include <linux/interrupt.h>
30
31/*
32 * State machine for state 1, Awaiting Connection State.
33 * The handling of the timer(s) is in file ax25_ds_timer.c.
34 * Handling of state 0 and connection release is in ax25.c.
35 */
36static int ax25_ds_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
37{
38 switch (frametype) {
39 case AX25_SABM:
40 ax25->modulus = AX25_MODULUS;
41 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
42 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
43 break;
44
45 case AX25_SABME:
46 ax25->modulus = AX25_EMODULUS;
47 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
48 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
49 break;
50
51 case AX25_DISC:
52 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
53 break;
54
55 case AX25_UA:
56 ax25_calculate_rtt(ax25);
57 ax25_stop_t1timer(ax25);
58 ax25_start_t3timer(ax25);
59 ax25_start_idletimer(ax25);
60 ax25->vs = 0;
61 ax25->va = 0;
62 ax25->vr = 0;
63 ax25->state = AX25_STATE_3;
64 ax25->n2count = 0;
65 if (ax25->sk != NULL) {
66 bh_lock_sock(ax25->sk);
67 ax25->sk->sk_state = TCP_ESTABLISHED;
68 /*
69 * For WAIT_SABM connections we will produce an accept
70 * ready socket here
71 */
72 if (!sock_flag(ax25->sk, SOCK_DEAD))
73 ax25->sk->sk_state_change(ax25->sk);
74 bh_unlock_sock(ax25->sk);
75 }
76 ax25_dama_on(ax25);
77
78 /* according to DK4EG's spec we are required to
79 * send a RR RESPONSE FINAL NR=0.
80 */
81
82 ax25_std_enquiry_response(ax25);
83 break;
84
85 case AX25_DM:
86 if (pf)
87 ax25_disconnect(ax25, ECONNREFUSED);
88 break;
89
90 default:
91 if (pf)
92 ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
93 break;
94 }
95
96 return 0;
97}
98
99/*
100 * State machine for state 2, Awaiting Release State.
101 * The handling of the timer(s) is in file ax25_ds_timer.c
102 * Handling of state 0 and connection release is in ax25.c.
103 */
104static int ax25_ds_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
105{
106 switch (frametype) {
107 case AX25_SABM:
108 case AX25_SABME:
109 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
110 ax25_dama_off(ax25);
111 break;
112
113 case AX25_DISC:
114 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
115 ax25_dama_off(ax25);
116 ax25_disconnect(ax25, 0);
117 break;
118
119 case AX25_DM:
120 case AX25_UA:
121 if (pf) {
122 ax25_dama_off(ax25);
123 ax25_disconnect(ax25, 0);
124 }
125 break;
126
127 case AX25_I:
128 case AX25_REJ:
129 case AX25_RNR:
130 case AX25_RR:
131 if (pf) {
132 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
133 ax25_dama_off(ax25);
134 }
135 break;
136
137 default:
138 break;
139 }
140
141 return 0;
142}
143
144/*
145 * State machine for state 3, Connected State.
146 * The handling of the timer(s) is in file ax25_timer.c
147 * Handling of state 0 and connection release is in ax25.c.
148 */
149static int ax25_ds_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
150{
151 int queued = 0;
152
153 switch (frametype) {
154 case AX25_SABM:
155 case AX25_SABME:
156 if (frametype == AX25_SABM) {
157 ax25->modulus = AX25_MODULUS;
158 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
159 } else {
160 ax25->modulus = AX25_EMODULUS;
161 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
162 }
163 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
164 ax25_stop_t1timer(ax25);
165 ax25_start_t3timer(ax25);
166 ax25_start_idletimer(ax25);
167 ax25->condition = 0x00;
168 ax25->vs = 0;
169 ax25->va = 0;
170 ax25->vr = 0;
171 ax25_requeue_frames(ax25);
172 ax25_dama_on(ax25);
173 break;
174
175 case AX25_DISC:
176 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
177 ax25_dama_off(ax25);
178 ax25_disconnect(ax25, 0);
179 break;
180
181 case AX25_DM:
182 ax25_dama_off(ax25);
183 ax25_disconnect(ax25, ECONNRESET);
184 break;
185
186 case AX25_RR:
187 case AX25_RNR:
188 if (frametype == AX25_RR)
189 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
190 else
191 ax25->condition |= AX25_COND_PEER_RX_BUSY;
192
193 if (ax25_validate_nr(ax25, nr)) {
194 if (ax25_check_iframes_acked(ax25, nr))
195 ax25->n2count=0;
196 if (type == AX25_COMMAND && pf)
197 ax25_ds_enquiry_response(ax25);
198 } else {
199 ax25_ds_nr_error_recovery(ax25);
200 ax25->state = AX25_STATE_1;
201 }
202 break;
203
204 case AX25_REJ:
205 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
206
207 if (ax25_validate_nr(ax25, nr)) {
208 if (ax25->va != nr)
209 ax25->n2count=0;
210
211 ax25_frames_acked(ax25, nr);
212 ax25_calculate_rtt(ax25);
213 ax25_stop_t1timer(ax25);
214 ax25_start_t3timer(ax25);
215 ax25_requeue_frames(ax25);
216
217 if (type == AX25_COMMAND && pf)
218 ax25_ds_enquiry_response(ax25);
219 } else {
220 ax25_ds_nr_error_recovery(ax25);
221 ax25->state = AX25_STATE_1;
222 }
223 break;
224
225 case AX25_I:
226 if (!ax25_validate_nr(ax25, nr)) {
227 ax25_ds_nr_error_recovery(ax25);
228 ax25->state = AX25_STATE_1;
229 break;
230 }
231 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
232 ax25_frames_acked(ax25, nr);
233 ax25->n2count = 0;
234 } else {
235 if (ax25_check_iframes_acked(ax25, nr))
236 ax25->n2count = 0;
237 }
238 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
239 if (pf) ax25_ds_enquiry_response(ax25);
240 break;
241 }
242 if (ns == ax25->vr) {
243 ax25->vr = (ax25->vr + 1) % ax25->modulus;
244 queued = ax25_rx_iframe(ax25, skb);
245 if (ax25->condition & AX25_COND_OWN_RX_BUSY)
246 ax25->vr = ns; /* ax25->vr - 1 */
247 ax25->condition &= ~AX25_COND_REJECT;
248 if (pf) {
249 ax25_ds_enquiry_response(ax25);
250 } else {
251 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
252 ax25->condition |= AX25_COND_ACK_PENDING;
253 ax25_start_t2timer(ax25);
254 }
255 }
256 } else {
257 if (ax25->condition & AX25_COND_REJECT) {
258 if (pf) ax25_ds_enquiry_response(ax25);
259 } else {
260 ax25->condition |= AX25_COND_REJECT;
261 ax25_ds_enquiry_response(ax25);
262 ax25->condition &= ~AX25_COND_ACK_PENDING;
263 }
264 }
265 break;
266
267 case AX25_FRMR:
268 case AX25_ILLEGAL:
269 ax25_ds_establish_data_link(ax25);
270 ax25->state = AX25_STATE_1;
271 break;
272
273 default:
274 break;
275 }
276
277 return queued;
278}
279
280/*
281 * Higher level upcall for a LAPB frame
282 */
283int ax25_ds_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
284{
285 int queued = 0, frametype, ns, nr, pf;
286
287 frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
288
289 switch (ax25->state) {
290 case AX25_STATE_1:
291 queued = ax25_ds_state1_machine(ax25, skb, frametype, pf, type);
292 break;
293 case AX25_STATE_2:
294 queued = ax25_ds_state2_machine(ax25, skb, frametype, pf, type);
295 break;
296 case AX25_STATE_3:
297 queued = ax25_ds_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
298 break;
299 }
300
301 return queued;
302}
303