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