5170d52bfd96e1e045422ae8e3cb607af2d2f843
[linux-2.6.git] / net / x25 / x25_subr.c
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