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rose_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  *
9  * Most of this code is based on the SDL diagrams published in the 7th ARRL
10  * Computer Networking Conference papers. The diagrams have mistakes in them,
11  * but are mostly correct. Before you modify the code could you read the SDL
12  * diagrams as the code is not obvious and probably very easy to break.
13  */
14 #include <linux/errno.h>
15 #include <linux/types.h>
16 #include <linux/socket.h>
17 #include <linux/in.h>
18 #include <linux/kernel.h>
19 #include <linux/timer.h>
20 #include <linux/string.h>
21 #include <linux/sockios.h>
22 #include <linux/net.h>
23 #include <net/ax25.h>
24 #include <linux/inet.h>
25 #include <linux/netdevice.h>
26 #include <linux/skbuff.h>
27 #include <net/sock.h>
28 #include <net/tcp_states.h>
29 #include <linux/fcntl.h>
30 #include <linux/mm.h>
31 #include <linux/interrupt.h>
32 #include <net/rose.h>
33 
34 /*
35  * State machine for state 1, Awaiting Call Accepted State.
36  * The handling of the timer(s) is in file rose_timer.c.
37  * Handling of state 0 and connection release is in af_rose.c.
38  */
39 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
40 {
41  struct rose_sock *rose = rose_sk(sk);
42 
43  switch (frametype) {
44  case ROSE_CALL_ACCEPTED:
45  rose_stop_timer(sk);
46  rose_start_idletimer(sk);
47  rose->condition = 0x00;
48  rose->vs = 0;
49  rose->va = 0;
50  rose->vr = 0;
51  rose->vl = 0;
52  rose->state = ROSE_STATE_3;
53  sk->sk_state = TCP_ESTABLISHED;
54  if (!sock_flag(sk, SOCK_DEAD))
55  sk->sk_state_change(sk);
56  break;
57 
58  case ROSE_CLEAR_REQUEST:
59  rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
60  rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
61  rose->neighbour->use--;
62  break;
63 
64  default:
65  break;
66  }
67 
68  return 0;
69 }
70 
71 /*
72  * State machine for state 2, Awaiting Clear Confirmation State.
73  * The handling of the timer(s) is in file rose_timer.c
74  * Handling of state 0 and connection release is in af_rose.c.
75  */
76 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
77 {
78  struct rose_sock *rose = rose_sk(sk);
79 
80  switch (frametype) {
81  case ROSE_CLEAR_REQUEST:
82  rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
83  rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
84  rose->neighbour->use--;
85  break;
86 
87  case ROSE_CLEAR_CONFIRMATION:
88  rose_disconnect(sk, 0, -1, -1);
89  rose->neighbour->use--;
90  break;
91 
92  default:
93  break;
94  }
95 
96  return 0;
97 }
98 
99 /*
100  * State machine for state 3, Connected State.
101  * The handling of the timer(s) is in file rose_timer.c
102  * Handling of state 0 and connection release is in af_rose.c.
103  */
104 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
105 {
106  struct rose_sock *rose = rose_sk(sk);
107  int queued = 0;
108 
109  switch (frametype) {
110  case ROSE_RESET_REQUEST:
111  rose_stop_timer(sk);
112  rose_start_idletimer(sk);
113  rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
114  rose->condition = 0x00;
115  rose->vs = 0;
116  rose->vr = 0;
117  rose->va = 0;
118  rose->vl = 0;
119  rose_requeue_frames(sk);
120  break;
121 
122  case ROSE_CLEAR_REQUEST:
123  rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
124  rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
125  rose->neighbour->use--;
126  break;
127 
128  case ROSE_RR:
129  case ROSE_RNR:
130  if (!rose_validate_nr(sk, nr)) {
131  rose_write_internal(sk, ROSE_RESET_REQUEST);
132  rose->condition = 0x00;
133  rose->vs = 0;
134  rose->vr = 0;
135  rose->va = 0;
136  rose->vl = 0;
137  rose->state = ROSE_STATE_4;
138  rose_start_t2timer(sk);
139  rose_stop_idletimer(sk);
140  } else {
141  rose_frames_acked(sk, nr);
142  if (frametype == ROSE_RNR) {
143  rose->condition |= ROSE_COND_PEER_RX_BUSY;
144  } else {
145  rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
146  }
147  }
148  break;
149 
150  case ROSE_DATA: /* XXX */
151  rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
152  if (!rose_validate_nr(sk, nr)) {
153  rose_write_internal(sk, ROSE_RESET_REQUEST);
154  rose->condition = 0x00;
155  rose->vs = 0;
156  rose->vr = 0;
157  rose->va = 0;
158  rose->vl = 0;
159  rose->state = ROSE_STATE_4;
160  rose_start_t2timer(sk);
161  rose_stop_idletimer(sk);
162  break;
163  }
164  rose_frames_acked(sk, nr);
165  if (ns == rose->vr) {
166  rose_start_idletimer(sk);
167  if (sock_queue_rcv_skb(sk, skb) == 0) {
168  rose->vr = (rose->vr + 1) % ROSE_MODULUS;
169  queued = 1;
170  } else {
171  /* Should never happen ! */
172  rose_write_internal(sk, ROSE_RESET_REQUEST);
173  rose->condition = 0x00;
174  rose->vs = 0;
175  rose->vr = 0;
176  rose->va = 0;
177  rose->vl = 0;
178  rose->state = ROSE_STATE_4;
179  rose_start_t2timer(sk);
180  rose_stop_idletimer(sk);
181  break;
182  }
183  if (atomic_read(&sk->sk_rmem_alloc) >
184  (sk->sk_rcvbuf >> 1))
185  rose->condition |= ROSE_COND_OWN_RX_BUSY;
186  }
187  /*
188  * If the window is full, ack the frame, else start the
189  * acknowledge hold back timer.
190  */
191  if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
192  rose->condition &= ~ROSE_COND_ACK_PENDING;
193  rose_stop_timer(sk);
194  rose_enquiry_response(sk);
195  } else {
196  rose->condition |= ROSE_COND_ACK_PENDING;
197  rose_start_hbtimer(sk);
198  }
199  break;
200 
201  default:
202  printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
203  break;
204  }
205 
206  return queued;
207 }
208 
209 /*
210  * State machine for state 4, Awaiting Reset Confirmation State.
211  * The handling of the timer(s) is in file rose_timer.c
212  * Handling of state 0 and connection release is in af_rose.c.
213  */
214 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
215 {
216  struct rose_sock *rose = rose_sk(sk);
217 
218  switch (frametype) {
219  case ROSE_RESET_REQUEST:
220  rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
221  case ROSE_RESET_CONFIRMATION:
222  rose_stop_timer(sk);
223  rose_start_idletimer(sk);
224  rose->condition = 0x00;
225  rose->va = 0;
226  rose->vr = 0;
227  rose->vs = 0;
228  rose->vl = 0;
229  rose->state = ROSE_STATE_3;
230  rose_requeue_frames(sk);
231  break;
232 
233  case ROSE_CLEAR_REQUEST:
234  rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
235  rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
236  rose->neighbour->use--;
237  break;
238 
239  default:
240  break;
241  }
242 
243  return 0;
244 }
245 
246 /*
247  * State machine for state 5, Awaiting Call Acceptance State.
248  * The handling of the timer(s) is in file rose_timer.c
249  * Handling of state 0 and connection release is in af_rose.c.
250  */
251 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
252 {
253  if (frametype == ROSE_CLEAR_REQUEST) {
254  rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
255  rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
256  rose_sk(sk)->neighbour->use--;
257  }
258 
259  return 0;
260 }
261 
262 /* Higher level upcall for a LAPB frame */
263 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
264 {
265  struct rose_sock *rose = rose_sk(sk);
266  int queued = 0, frametype, ns, nr, q, d, m;
267 
268  if (rose->state == ROSE_STATE_0)
269  return 0;
270 
271  frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
272 
273  switch (rose->state) {
274  case ROSE_STATE_1:
275  queued = rose_state1_machine(sk, skb, frametype);
276  break;
277  case ROSE_STATE_2:
278  queued = rose_state2_machine(sk, skb, frametype);
279  break;
280  case ROSE_STATE_3:
281  queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
282  break;
283  case ROSE_STATE_4:
284  queued = rose_state4_machine(sk, skb, frametype);
285  break;
286  case ROSE_STATE_5:
287  queued = rose_state5_machine(sk, skb, frametype);
288  break;
289  }
290 
291  rose_kick(sk);
292 
293  return queued;
294 }
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