1 /*
2 * AX.25 release 037
3 *
4 * This code REQUIRES 2.1.15 or higher/ NET3.038
5 *
6 * This module:
7 * This module is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 * Most of this code is based on the SDL diagrams published in the 7th
13 * ARRL Computer Networking Conference papers. The diagrams have mistakes
14 * in them, but are mostly correct. Before you modify the code could you
15 * read the SDL diagrams as the code is not obvious and probably very
16 * easy to break;
17 *
18 * History
19 * AX.25 036 Jonathan(G4KLX) Cloned from ax25_in.c
20 * Joerg(DL1BKE) Fixed it.
21 * AX.25 037 Jonathan(G4KLX) New timer architecture.
22 * Joerg(DL1BKE) ax25->n2count never got reset
23 */
24
25 #include <linux/errno.h>
26 #include <linux/types.h>
27 #include <linux/socket.h>
28 #include <linux/in.h>
29 #include <linux/kernel.h>
30 #include <linux/sched.h>
31 #include <linux/timer.h>
32 #include <linux/string.h>
33 #include <linux/sockios.h>
34 #include <linux/net.h>
35 #include <net/ax25.h>
36 #include <linux/inet.h>
37 #include <linux/netdevice.h>
38 #include <linux/skbuff.h>
39 #include <net/sock.h>
40 #include <net/ip.h> /* For ip_rcv */
41 #include <asm/uaccess.h>
42 #include <asm/system.h>
43 #include <linux/fcntl.h>
44 #include <linux/mm.h>
45 #include <linux/interrupt.h>
46
47 /*
48 * State machine for state 1, Awaiting Connection State.
49 * The handling of the timer(s) is in file ax25_ds_timer.c.
50 * Handling of state 0 and connection release is in ax25.c.
51 */
ax25_ds_state1_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int pf,int type)52 static int ax25_ds_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
53 {
54 switch (frametype) {
55 case AX25_SABM:
56 ax25->modulus = AX25_MODULUS;
57 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
58 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
59 break;
60
61 case AX25_SABME:
62 ax25->modulus = AX25_EMODULUS;
63 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
64 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
65 break;
66
67 case AX25_DISC:
68 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
69 break;
70
71 case AX25_UA:
72 ax25_calculate_rtt(ax25);
73 ax25_stop_t1timer(ax25);
74 ax25_start_t3timer(ax25);
75 ax25_start_idletimer(ax25);
76 ax25->vs = 0;
77 ax25->va = 0;
78 ax25->vr = 0;
79 ax25->state = AX25_STATE_3;
80 ax25->n2count = 0;
81 if (ax25->sk != NULL) {
82 ax25->sk->state = TCP_ESTABLISHED;
83 /* For WAIT_SABM connections we will produce an accept ready socket here */
84 if (!ax25->sk->dead)
85 ax25->sk->state_change(ax25->sk);
86 }
87 ax25_dama_on(ax25);
88
89 /* according to DK4EG�s spec we are required to
90 * send a RR RESPONSE FINAL NR=0.
91 */
92
93 ax25_std_enquiry_response(ax25);
94 break;
95
96 case AX25_DM:
97 if (pf) ax25_disconnect(ax25, ECONNREFUSED);
98 break;
99
100 default:
101 if (pf) ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
102 break;
103 }
104
105 return 0;
106 }
107
108 /*
109 * State machine for state 2, Awaiting Release State.
110 * The handling of the timer(s) is in file ax25_ds_timer.c
111 * Handling of state 0 and connection release is in ax25.c.
112 */
ax25_ds_state2_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int pf,int type)113 static int ax25_ds_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
114 {
115 switch (frametype) {
116 case AX25_SABM:
117 case AX25_SABME:
118 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
119 ax25_dama_off(ax25);
120 break;
121
122 case AX25_DISC:
123 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
124 ax25_dama_off(ax25);
125 ax25_disconnect(ax25, 0);
126 break;
127
128 case AX25_DM:
129 case AX25_UA:
130 if (pf) {
131 ax25_dama_off(ax25);
132 ax25_disconnect(ax25, 0);
133 }
134 break;
135
136 case AX25_I:
137 case AX25_REJ:
138 case AX25_RNR:
139 case AX25_RR:
140 if (pf) {
141 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
142 ax25_dama_off(ax25);
143 }
144 break;
145
146 default:
147 break;
148 }
149
150 return 0;
151 }
152
153 /*
154 * State machine for state 3, Connected State.
155 * The handling of the timer(s) is in file ax25_timer.c
156 * Handling of state 0 and connection release is in ax25.c.
157 */
ax25_ds_state3_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int ns,int nr,int pf,int type)158 static int ax25_ds_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
159 {
160 int queued = 0;
161
162 switch (frametype) {
163 case AX25_SABM:
164 case AX25_SABME:
165 if (frametype == AX25_SABM) {
166 ax25->modulus = AX25_MODULUS;
167 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
168 } else {
169 ax25->modulus = AX25_EMODULUS;
170 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
171 }
172 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
173 ax25_stop_t1timer(ax25);
174 ax25_start_t3timer(ax25);
175 ax25_start_idletimer(ax25);
176 ax25->condition = 0x00;
177 ax25->vs = 0;
178 ax25->va = 0;
179 ax25->vr = 0;
180 ax25_requeue_frames(ax25);
181 ax25_dama_on(ax25);
182 break;
183
184 case AX25_DISC:
185 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
186 ax25_dama_off(ax25);
187 ax25_disconnect(ax25, 0);
188 break;
189
190 case AX25_DM:
191 ax25_dama_off(ax25);
192 ax25_disconnect(ax25, ECONNRESET);
193 break;
194
195 case AX25_RR:
196 case AX25_RNR:
197 if (frametype == AX25_RR)
198 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
199 else
200 ax25->condition |= AX25_COND_PEER_RX_BUSY;
201
202 if (ax25_validate_nr(ax25, nr)) {
203 if (ax25_check_iframes_acked(ax25, nr))
204 ax25->n2count=0;
205 if (type == AX25_COMMAND && pf)
206 ax25_ds_enquiry_response(ax25);
207 } else {
208 ax25_ds_nr_error_recovery(ax25);
209 ax25->state = AX25_STATE_1;
210 }
211 break;
212
213 case AX25_REJ:
214 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
215
216 if (ax25_validate_nr(ax25, nr)) {
217 if (ax25->va != nr)
218 ax25->n2count=0;
219
220 ax25_frames_acked(ax25, nr);
221 ax25_calculate_rtt(ax25);
222 ax25_stop_t1timer(ax25);
223 ax25_start_t3timer(ax25);
224 ax25_requeue_frames(ax25);
225
226 if (type == AX25_COMMAND && pf)
227 ax25_ds_enquiry_response(ax25);
228 } else {
229 ax25_ds_nr_error_recovery(ax25);
230 ax25->state = AX25_STATE_1;
231 }
232 break;
233
234 case AX25_I:
235 if (!ax25_validate_nr(ax25, nr)) {
236 ax25_ds_nr_error_recovery(ax25);
237 ax25->state = AX25_STATE_1;
238 break;
239 }
240 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
241 ax25_frames_acked(ax25, nr);
242 ax25->n2count = 0;
243 } else {
244 if (ax25_check_iframes_acked(ax25, nr))
245 ax25->n2count = 0;
246 }
247 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
248 if (pf) ax25_ds_enquiry_response(ax25);
249 break;
250 }
251 if (ns == ax25->vr) {
252 ax25->vr = (ax25->vr + 1) % ax25->modulus;
253 queued = ax25_rx_iframe(ax25, skb);
254 if (ax25->condition & AX25_COND_OWN_RX_BUSY)
255 ax25->vr = ns; /* ax25->vr - 1 */
256 ax25->condition &= ~AX25_COND_REJECT;
257 if (pf) {
258 ax25_ds_enquiry_response(ax25);
259 } else {
260 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
261 ax25->condition |= AX25_COND_ACK_PENDING;
262 ax25_start_t2timer(ax25);
263 }
264 }
265 } else {
266 if (ax25->condition & AX25_COND_REJECT) {
267 if (pf) ax25_ds_enquiry_response(ax25);
268 } else {
269 ax25->condition |= AX25_COND_REJECT;
270 ax25_ds_enquiry_response(ax25);
271 ax25->condition &= ~AX25_COND_ACK_PENDING;
272 }
273 }
274 break;
275
276 case AX25_FRMR:
277 case AX25_ILLEGAL:
278 ax25_ds_establish_data_link(ax25);
279 ax25->state = AX25_STATE_1;
280 break;
281
282 default:
283 break;
284 }
285
286 return queued;
287 }
288
289 /*
290 * Higher level upcall for a LAPB frame
291 */
ax25_ds_frame_in(ax25_cb * ax25,struct sk_buff * skb,int type)292 int ax25_ds_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
293 {
294 int queued = 0, frametype, ns, nr, pf;
295
296 frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
297
298 switch (ax25->state) {
299 case AX25_STATE_1:
300 queued = ax25_ds_state1_machine(ax25, skb, frametype, pf, type);
301 break;
302 case AX25_STATE_2:
303 queued = ax25_ds_state2_machine(ax25, skb, frametype, pf, type);
304 break;
305 case AX25_STATE_3:
306 queued = ax25_ds_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
307 break;
308 }
309
310 return queued;
311 }
312
313