Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
x25_subr.c
Go to the documentation of this file.
1 /*
2  * X.25 Packet Layer release 002
3  *
4  * This is ALPHA test software. This code may break your machine,
5  * randomly fail to work with new releases, misbehave and/or generally
6  * screw up. It might even work.
7  *
8  * This code REQUIRES 2.1.15 or higher
9  *
10  * This module:
11  * This module is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License
13  * as published by the Free Software Foundation; either version
14  * 2 of the License, or (at your option) any later version.
15  *
16  * History
17  * X.25 001 Jonathan Naylor Started coding.
18  * X.25 002 Jonathan Naylor Centralised disconnection processing.
19  * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
20  * negotiation.
21  * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
22  * apr/04/15 Shaun Pereira Fast select with no
23  * restriction on response.
24  */
25 
26 #include <linux/slab.h>
27 #include <linux/kernel.h>
28 #include <linux/string.h>
29 #include <linux/skbuff.h>
30 #include <net/sock.h>
31 #include <net/tcp_states.h>
32 #include <net/x25.h>
33 
34 /*
35  * This routine purges all of the queues of frames.
36  */
37 void x25_clear_queues(struct sock *sk)
38 {
39  struct x25_sock *x25 = x25_sk(sk);
40 
41  skb_queue_purge(&sk->sk_write_queue);
42  skb_queue_purge(&x25->ack_queue);
43  skb_queue_purge(&x25->interrupt_in_queue);
44  skb_queue_purge(&x25->interrupt_out_queue);
45  skb_queue_purge(&x25->fragment_queue);
46 }
47 
48 
49 /*
50  * This routine purges the input queue of those frames that have been
51  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
52  * SDL diagram.
53 */
54 void x25_frames_acked(struct sock *sk, unsigned short nr)
55 {
56  struct sk_buff *skb;
57  struct x25_sock *x25 = x25_sk(sk);
58  int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
59 
60  /*
61  * Remove all the ack-ed frames from the ack queue.
62  */
63  if (x25->va != nr)
64  while (skb_peek(&x25->ack_queue) && x25->va != nr) {
65  skb = skb_dequeue(&x25->ack_queue);
66  kfree_skb(skb);
67  x25->va = (x25->va + 1) % modulus;
68  }
69 }
70 
71 void x25_requeue_frames(struct sock *sk)
72 {
73  struct sk_buff *skb, *skb_prev = NULL;
74 
75  /*
76  * Requeue all the un-ack-ed frames on the output queue to be picked
77  * up by x25_kick. This arrangement handles the possibility of an empty
78  * output queue.
79  */
80  while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
81  if (!skb_prev)
82  skb_queue_head(&sk->sk_write_queue, skb);
83  else
84  skb_append(skb_prev, skb, &sk->sk_write_queue);
85  skb_prev = skb;
86  }
87 }
88 
89 /*
90  * Validate that the value of nr is between va and vs. Return true or
91  * false for testing.
92  */
93 int x25_validate_nr(struct sock *sk, unsigned short nr)
94 {
95  struct x25_sock *x25 = x25_sk(sk);
96  unsigned short vc = x25->va;
97  int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
98 
99  while (vc != x25->vs) {
100  if (nr == vc)
101  return 1;
102  vc = (vc + 1) % modulus;
103  }
104 
105  return nr == x25->vs ? 1 : 0;
106 }
107 
108 /*
109  * This routine is called when the packet layer internally generates a
110  * control frame.
111  */
112 void x25_write_internal(struct sock *sk, int frametype)
113 {
114  struct x25_sock *x25 = x25_sk(sk);
115  struct sk_buff *skb;
116  unsigned char *dptr;
117  unsigned char facilities[X25_MAX_FAC_LEN];
118  unsigned char addresses[1 + X25_ADDR_LEN];
119  unsigned char lci1, lci2;
120  /*
121  * Default safe frame size.
122  */
123  int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
124 
125  /*
126  * Adjust frame size.
127  */
128  switch (frametype) {
129  case X25_CALL_REQUEST:
130  len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
131  break;
132  case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
133  if (x25->facilities.reverse & 0x80) {
134  len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
135  } else {
136  len += 1 + X25_MAX_FAC_LEN;
137  }
138  break;
139  case X25_CLEAR_REQUEST:
140  case X25_RESET_REQUEST:
141  len += 2;
142  break;
143  case X25_RR:
144  case X25_RNR:
145  case X25_REJ:
146  case X25_CLEAR_CONFIRMATION:
147  case X25_INTERRUPT_CONFIRMATION:
148  case X25_RESET_CONFIRMATION:
149  break;
150  default:
151  printk(KERN_ERR "X.25: invalid frame type %02X\n", frametype);
152  return;
153  }
154 
155  if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
156  return;
157 
158  /*
159  * Space for Ethernet and 802.2 LLC headers.
160  */
161  skb_reserve(skb, X25_MAX_L2_LEN);
162 
163  /*
164  * Make space for the GFI and LCI, and fill them in.
165  */
166  dptr = skb_put(skb, 2);
167 
168  lci1 = (x25->lci >> 8) & 0x0F;
169  lci2 = (x25->lci >> 0) & 0xFF;
170 
171  if (x25->neighbour->extended) {
172  *dptr++ = lci1 | X25_GFI_EXTSEQ;
173  *dptr++ = lci2;
174  } else {
175  *dptr++ = lci1 | X25_GFI_STDSEQ;
176  *dptr++ = lci2;
177  }
178 
179  /*
180  * Now fill in the frame type specific information.
181  */
182  switch (frametype) {
183 
184  case X25_CALL_REQUEST:
185  dptr = skb_put(skb, 1);
186  *dptr++ = X25_CALL_REQUEST;
187  len = x25_addr_aton(addresses, &x25->dest_addr,
188  &x25->source_addr);
189  dptr = skb_put(skb, len);
190  memcpy(dptr, addresses, len);
191  len = x25_create_facilities(facilities,
192  &x25->facilities,
193  &x25->dte_facilities,
194  x25->neighbour->global_facil_mask);
195  dptr = skb_put(skb, len);
196  memcpy(dptr, facilities, len);
197  dptr = skb_put(skb, x25->calluserdata.cudlength);
198  memcpy(dptr, x25->calluserdata.cuddata,
199  x25->calluserdata.cudlength);
200  x25->calluserdata.cudlength = 0;
201  break;
202 
203  case X25_CALL_ACCEPTED:
204  dptr = skb_put(skb, 2);
205  *dptr++ = X25_CALL_ACCEPTED;
206  *dptr++ = 0x00; /* Address lengths */
207  len = x25_create_facilities(facilities,
208  &x25->facilities,
209  &x25->dte_facilities,
210  x25->vc_facil_mask);
211  dptr = skb_put(skb, len);
212  memcpy(dptr, facilities, len);
213 
214  /* fast select with no restriction on response
215  allows call user data. Userland must
216  ensure it is ours and not theirs */
217  if(x25->facilities.reverse & 0x80) {
218  dptr = skb_put(skb,
219  x25->calluserdata.cudlength);
220  memcpy(dptr, x25->calluserdata.cuddata,
221  x25->calluserdata.cudlength);
222  }
223  x25->calluserdata.cudlength = 0;
224  break;
225 
226  case X25_CLEAR_REQUEST:
227  dptr = skb_put(skb, 3);
228  *dptr++ = frametype;
229  *dptr++ = x25->causediag.cause;
230  *dptr++ = x25->causediag.diagnostic;
231  break;
232 
233  case X25_RESET_REQUEST:
234  dptr = skb_put(skb, 3);
235  *dptr++ = frametype;
236  *dptr++ = 0x00; /* XXX */
237  *dptr++ = 0x00; /* XXX */
238  break;
239 
240  case X25_RR:
241  case X25_RNR:
242  case X25_REJ:
243  if (x25->neighbour->extended) {
244  dptr = skb_put(skb, 2);
245  *dptr++ = frametype;
246  *dptr++ = (x25->vr << 1) & 0xFE;
247  } else {
248  dptr = skb_put(skb, 1);
249  *dptr = frametype;
250  *dptr++ |= (x25->vr << 5) & 0xE0;
251  }
252  break;
253 
254  case X25_CLEAR_CONFIRMATION:
255  case X25_INTERRUPT_CONFIRMATION:
256  case X25_RESET_CONFIRMATION:
257  dptr = skb_put(skb, 1);
258  *dptr = frametype;
259  break;
260  }
261 
262  x25_transmit_link(skb, x25->neighbour);
263 }
264 
265 /*
266  * Unpick the contents of the passed X.25 Packet Layer frame.
267  */
268 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
269  int *d, int *m)
270 {
271  struct x25_sock *x25 = x25_sk(sk);
272  unsigned char *frame;
273 
274  if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
275  return X25_ILLEGAL;
276  frame = skb->data;
277 
278  *ns = *nr = *q = *d = *m = 0;
279 
280  switch (frame[2]) {
281  case X25_CALL_REQUEST:
282  case X25_CALL_ACCEPTED:
283  case X25_CLEAR_REQUEST:
284  case X25_CLEAR_CONFIRMATION:
285  case X25_INTERRUPT:
286  case X25_INTERRUPT_CONFIRMATION:
287  case X25_RESET_REQUEST:
288  case X25_RESET_CONFIRMATION:
289  case X25_RESTART_REQUEST:
290  case X25_RESTART_CONFIRMATION:
291  case X25_REGISTRATION_REQUEST:
292  case X25_REGISTRATION_CONFIRMATION:
293  case X25_DIAGNOSTIC:
294  return frame[2];
295  }
296 
297  if (x25->neighbour->extended) {
298  if (frame[2] == X25_RR ||
299  frame[2] == X25_RNR ||
300  frame[2] == X25_REJ) {
301  if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
302  return X25_ILLEGAL;
303  frame = skb->data;
304 
305  *nr = (frame[3] >> 1) & 0x7F;
306  return frame[2];
307  }
308  } else {
309  if ((frame[2] & 0x1F) == X25_RR ||
310  (frame[2] & 0x1F) == X25_RNR ||
311  (frame[2] & 0x1F) == X25_REJ) {
312  *nr = (frame[2] >> 5) & 0x07;
313  return frame[2] & 0x1F;
314  }
315  }
316 
317  if (x25->neighbour->extended) {
318  if ((frame[2] & 0x01) == X25_DATA) {
319  if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
320  return X25_ILLEGAL;
321  frame = skb->data;
322 
323  *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
324  *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
325  *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
326  *nr = (frame[3] >> 1) & 0x7F;
327  *ns = (frame[2] >> 1) & 0x7F;
328  return X25_DATA;
329  }
330  } else {
331  if ((frame[2] & 0x01) == X25_DATA) {
332  *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
333  *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
334  *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
335  *nr = (frame[2] >> 5) & 0x07;
336  *ns = (frame[2] >> 1) & 0x07;
337  return X25_DATA;
338  }
339  }
340 
341  printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
342  frame[0], frame[1], frame[2]);
343 
344  return X25_ILLEGAL;
345 }
346 
347 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
348  unsigned char diagnostic)
349 {
350  struct x25_sock *x25 = x25_sk(sk);
351 
352  x25_clear_queues(sk);
353  x25_stop_timer(sk);
354 
355  x25->lci = 0;
356  x25->state = X25_STATE_0;
357 
358  x25->causediag.cause = cause;
359  x25->causediag.diagnostic = diagnostic;
360 
361  sk->sk_state = TCP_CLOSE;
362  sk->sk_err = reason;
363  sk->sk_shutdown |= SEND_SHUTDOWN;
364 
365  if (!sock_flag(sk, SOCK_DEAD)) {
366  sk->sk_state_change(sk);
367  sock_set_flag(sk, SOCK_DEAD);
368  }
369 }
370 
371 /*
372  * Clear an own-rx-busy condition and tell the peer about this, provided
373  * that there is a significant amount of free receive buffer space available.
374  */
375 void x25_check_rbuf(struct sock *sk)
376 {
377  struct x25_sock *x25 = x25_sk(sk);
378 
379  if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
380  (x25->condition & X25_COND_OWN_RX_BUSY)) {
381  x25->condition &= ~X25_COND_OWN_RX_BUSY;
382  x25->condition &= ~X25_COND_ACK_PENDING;
383  x25->vl = x25->vr;
384  x25_write_internal(sk, X25_RR);
385  x25_stop_timer(sk);
386  }
387 }
388 
Generated on Thu Jan 10 2013 15:02:38 for Linux Kernel by   doxygen 1.8.2