1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
6 */
7 #include <linux/errno.h>
8 #include <linux/types.h>
9 #include <linux/socket.h>
10 #include <linux/in.h>
11 #include <linux/kernel.h>
12 #include <linux/timer.h>
13 #include <linux/string.h>
14 #include <linux/sockios.h>
15 #include <linux/net.h>
16 #include <net/ax25.h>
17 #include <linux/inet.h>
18 #include <linux/netdevice.h>
19 #include <linux/skbuff.h>
20 #include <net/sock.h>
21 #include <net/tcp_states.h>
22 #include <linux/uaccess.h>
23 #include <linux/fcntl.h>
24 #include <linux/mm.h>
25 #include <linux/interrupt.h>
26
27 /*
28 * State machine for state 1, Awaiting Connection State.
29 * The handling of the timer(s) is in file ax25_ds_timer.c.
30 * Handling of state 0 and connection release is in ax25.c.
31 */
ax25_ds_state1_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int pf,int type)32 static int ax25_ds_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
33 {
34 switch (frametype) {
35 case AX25_SABM:
36 ax25->modulus = AX25_MODULUS;
37 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
38 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
39 break;
40
41 case AX25_SABME:
42 ax25->modulus = AX25_EMODULUS;
43 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
44 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
45 break;
46
47 case AX25_DISC:
48 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
49 break;
50
51 case AX25_UA:
52 ax25_calculate_rtt(ax25);
53 ax25_stop_t1timer(ax25);
54 ax25_start_t3timer(ax25);
55 ax25_start_idletimer(ax25);
56 ax25->vs = 0;
57 ax25->va = 0;
58 ax25->vr = 0;
59 ax25->state = AX25_STATE_3;
60 ax25->n2count = 0;
61 if (ax25->sk != NULL) {
62 bh_lock_sock(ax25->sk);
63 ax25->sk->sk_state = TCP_ESTABLISHED;
64 /*
65 * For WAIT_SABM connections we will produce an accept
66 * ready socket here
67 */
68 if (!sock_flag(ax25->sk, SOCK_DEAD))
69 ax25->sk->sk_state_change(ax25->sk);
70 bh_unlock_sock(ax25->sk);
71 }
72 ax25_dama_on(ax25);
73
74 /* according to DK4EG's spec we are required to
75 * send a RR RESPONSE FINAL NR=0.
76 */
77
78 ax25_std_enquiry_response(ax25);
79 break;
80
81 case AX25_DM:
82 if (pf)
83 ax25_disconnect(ax25, ECONNREFUSED);
84 break;
85
86 default:
87 if (pf)
88 ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
89 break;
90 }
91
92 return 0;
93 }
94
95 /*
96 * State machine for state 2, Awaiting Release State.
97 * The handling of the timer(s) is in file ax25_ds_timer.c
98 * Handling of state 0 and connection release is in ax25.c.
99 */
ax25_ds_state2_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int pf,int type)100 static int ax25_ds_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
101 {
102 switch (frametype) {
103 case AX25_SABM:
104 case AX25_SABME:
105 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
106 ax25_dama_off(ax25);
107 break;
108
109 case AX25_DISC:
110 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
111 ax25_dama_off(ax25);
112 ax25_disconnect(ax25, 0);
113 break;
114
115 case AX25_DM:
116 case AX25_UA:
117 if (pf) {
118 ax25_dama_off(ax25);
119 ax25_disconnect(ax25, 0);
120 }
121 break;
122
123 case AX25_I:
124 case AX25_REJ:
125 case AX25_RNR:
126 case AX25_RR:
127 if (pf) {
128 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
129 ax25_dama_off(ax25);
130 }
131 break;
132
133 default:
134 break;
135 }
136
137 return 0;
138 }
139
140 /*
141 * State machine for state 3, Connected State.
142 * The handling of the timer(s) is in file ax25_timer.c
143 * Handling of state 0 and connection release is in ax25.c.
144 */
ax25_ds_state3_machine(ax25_cb * ax25,struct sk_buff * skb,int frametype,int ns,int nr,int pf,int type)145 static int ax25_ds_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
146 {
147 int queued = 0;
148
149 switch (frametype) {
150 case AX25_SABM:
151 case AX25_SABME:
152 if (frametype == AX25_SABM) {
153 ax25->modulus = AX25_MODULUS;
154 ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
155 } else {
156 ax25->modulus = AX25_EMODULUS;
157 ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
158 }
159 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
160 ax25_stop_t1timer(ax25);
161 ax25_start_t3timer(ax25);
162 ax25_start_idletimer(ax25);
163 ax25->condition = 0x00;
164 ax25->vs = 0;
165 ax25->va = 0;
166 ax25->vr = 0;
167 ax25_requeue_frames(ax25);
168 ax25_dama_on(ax25);
169 break;
170
171 case AX25_DISC:
172 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
173 ax25_dama_off(ax25);
174 ax25_disconnect(ax25, 0);
175 break;
176
177 case AX25_DM:
178 ax25_dama_off(ax25);
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
189 if (ax25_validate_nr(ax25, nr)) {
190 if (ax25_check_iframes_acked(ax25, nr))
191 ax25->n2count=0;
192 if (type == AX25_COMMAND && pf)
193 ax25_ds_enquiry_response(ax25);
194 } else {
195 ax25_ds_nr_error_recovery(ax25);
196 ax25->state = AX25_STATE_1;
197 }
198 break;
199
200 case AX25_REJ:
201 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
202
203 if (ax25_validate_nr(ax25, nr)) {
204 if (ax25->va != nr)
205 ax25->n2count=0;
206
207 ax25_frames_acked(ax25, nr);
208 ax25_calculate_rtt(ax25);
209 ax25_stop_t1timer(ax25);
210 ax25_start_t3timer(ax25);
211 ax25_requeue_frames(ax25);
212
213 if (type == AX25_COMMAND && pf)
214 ax25_ds_enquiry_response(ax25);
215 } else {
216 ax25_ds_nr_error_recovery(ax25);
217 ax25->state = AX25_STATE_1;
218 }
219 break;
220
221 case AX25_I:
222 if (!ax25_validate_nr(ax25, nr)) {
223 ax25_ds_nr_error_recovery(ax25);
224 ax25->state = AX25_STATE_1;
225 break;
226 }
227 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
228 ax25_frames_acked(ax25, nr);
229 ax25->n2count = 0;
230 } else {
231 if (ax25_check_iframes_acked(ax25, nr))
232 ax25->n2count = 0;
233 }
234 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
235 if (pf) ax25_ds_enquiry_response(ax25);
236 break;
237 }
238 if (ns == ax25->vr) {
239 ax25->vr = (ax25->vr + 1) % ax25->modulus;
240 queued = ax25_rx_iframe(ax25, skb);
241 if (ax25->condition & AX25_COND_OWN_RX_BUSY)
242 ax25->vr = ns; /* ax25->vr - 1 */
243 ax25->condition &= ~AX25_COND_REJECT;
244 if (pf) {
245 ax25_ds_enquiry_response(ax25);
246 } else {
247 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
248 ax25->condition |= AX25_COND_ACK_PENDING;
249 ax25_start_t2timer(ax25);
250 }
251 }
252 } else {
253 if (ax25->condition & AX25_COND_REJECT) {
254 if (pf) ax25_ds_enquiry_response(ax25);
255 } else {
256 ax25->condition |= AX25_COND_REJECT;
257 ax25_ds_enquiry_response(ax25);
258 ax25->condition &= ~AX25_COND_ACK_PENDING;
259 }
260 }
261 break;
262
263 case AX25_FRMR:
264 case AX25_ILLEGAL:
265 ax25_ds_establish_data_link(ax25);
266 ax25->state = AX25_STATE_1;
267 break;
268
269 default:
270 break;
271 }
272
273 return queued;
274 }
275
276 /*
277 * Higher level upcall for a LAPB frame
278 */
ax25_ds_frame_in(ax25_cb * ax25,struct sk_buff * skb,int type)279 int ax25_ds_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
280 {
281 int queued = 0, frametype, ns, nr, pf;
282
283 frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
284
285 switch (ax25->state) {
286 case AX25_STATE_1:
287 queued = ax25_ds_state1_machine(ax25, skb, frametype, pf, type);
288 break;
289 case AX25_STATE_2:
290 queued = ax25_ds_state2_machine(ax25, skb, frametype, pf, type);
291 break;
292 case AX25_STATE_3:
293 queued = ax25_ds_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
294 break;
295 }
296
297 return queued;
298 }
299
