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Linux/net/x25/x25_subr.c

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  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 #define pr_fmt(fmt) "X25: " fmt
 27 
 28 #include <linux/slab.h>
 29 #include <linux/kernel.h>
 30 #include <linux/string.h>
 31 #include <linux/skbuff.h>
 32 #include <net/sock.h>
 33 #include <net/tcp_states.h>
 34 #include <net/x25.h>
 35 
 36 /*
 37  *      This routine purges all of the queues of frames.
 38  */
 39 void x25_clear_queues(struct sock *sk)
 40 {
 41         struct x25_sock *x25 = x25_sk(sk);
 42 
 43         skb_queue_purge(&sk->sk_write_queue);
 44         skb_queue_purge(&x25->ack_queue);
 45         skb_queue_purge(&x25->interrupt_in_queue);
 46         skb_queue_purge(&x25->interrupt_out_queue);
 47         skb_queue_purge(&x25->fragment_queue);
 48 }
 49 
 50 
 51 /*
 52  * This routine purges the input queue of those frames that have been
 53  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
 54  * SDL diagram.
 55 */
 56 void x25_frames_acked(struct sock *sk, unsigned short nr)
 57 {
 58         struct sk_buff *skb;
 59         struct x25_sock *x25 = x25_sk(sk);
 60         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
 61 
 62         /*
 63          * Remove all the ack-ed frames from the ack queue.
 64          */
 65         if (x25->va != nr)
 66                 while (skb_peek(&x25->ack_queue) && x25->va != nr) {
 67                         skb = skb_dequeue(&x25->ack_queue);
 68                         kfree_skb(skb);
 69                         x25->va = (x25->va + 1) % modulus;
 70                 }
 71 }
 72 
 73 void x25_requeue_frames(struct sock *sk)
 74 {
 75         struct sk_buff *skb, *skb_prev = NULL;
 76 
 77         /*
 78          * Requeue all the un-ack-ed frames on the output queue to be picked
 79          * up by x25_kick. This arrangement handles the possibility of an empty
 80          * output queue.
 81          */
 82         while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
 83                 if (!skb_prev)
 84                         skb_queue_head(&sk->sk_write_queue, skb);
 85                 else
 86                         skb_append(skb_prev, skb, &sk->sk_write_queue);
 87                 skb_prev = skb;
 88         }
 89 }
 90 
 91 /*
 92  *      Validate that the value of nr is between va and vs. Return true or
 93  *      false for testing.
 94  */
 95 int x25_validate_nr(struct sock *sk, unsigned short nr)
 96 {
 97         struct x25_sock *x25 = x25_sk(sk);
 98         unsigned short vc = x25->va;
 99         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
100 
101         while (vc != x25->vs) {
102                 if (nr == vc)
103                         return 1;
104                 vc = (vc + 1) % modulus;
105         }
106 
107         return nr == x25->vs ? 1 : 0;
108 }
109 
110 /*
111  *  This routine is called when the packet layer internally generates a
112  *  control frame.
113  */
114 void x25_write_internal(struct sock *sk, int frametype)
115 {
116         struct x25_sock *x25 = x25_sk(sk);
117         struct sk_buff *skb;
118         unsigned char  *dptr;
119         unsigned char  facilities[X25_MAX_FAC_LEN];
120         unsigned char  addresses[1 + X25_ADDR_LEN];
121         unsigned char  lci1, lci2;
122         /*
123          *      Default safe frame size.
124          */
125         int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
126 
127         /*
128          *      Adjust frame size.
129          */
130         switch (frametype) {
131         case X25_CALL_REQUEST:
132                 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
133                 break;
134         case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
135                 if (x25->facilities.reverse & 0x80) {
136                         len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
137                 } else {
138                         len += 1 + X25_MAX_FAC_LEN;
139                 }
140                 break;
141         case X25_CLEAR_REQUEST:
142         case X25_RESET_REQUEST:
143                 len += 2;
144                 break;
145         case X25_RR:
146         case X25_RNR:
147         case X25_REJ:
148         case X25_CLEAR_CONFIRMATION:
149         case X25_INTERRUPT_CONFIRMATION:
150         case X25_RESET_CONFIRMATION:
151                 break;
152         default:
153                 pr_err("invalid frame type %02X\n", frametype);
154                 return;
155         }
156 
157         if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
158                 return;
159 
160         /*
161          *      Space for Ethernet and 802.2 LLC headers.
162          */
163         skb_reserve(skb, X25_MAX_L2_LEN);
164 
165         /*
166          *      Make space for the GFI and LCI, and fill them in.
167          */
168         dptr = skb_put(skb, 2);
169 
170         lci1 = (x25->lci >> 8) & 0x0F;
171         lci2 = (x25->lci >> 0) & 0xFF;
172 
173         if (x25->neighbour->extended) {
174                 *dptr++ = lci1 | X25_GFI_EXTSEQ;
175                 *dptr++ = lci2;
176         } else {
177                 *dptr++ = lci1 | X25_GFI_STDSEQ;
178                 *dptr++ = lci2;
179         }
180 
181         /*
182          *      Now fill in the frame type specific information.
183          */
184         switch (frametype) {
185 
186                 case X25_CALL_REQUEST:
187                         dptr    = skb_put(skb, 1);
188                         *dptr++ = X25_CALL_REQUEST;
189                         len     = x25_addr_aton(addresses, &x25->dest_addr,
190                                                 &x25->source_addr);
191                         dptr    = skb_put(skb, len);
192                         memcpy(dptr, addresses, len);
193                         len     = x25_create_facilities(facilities,
194                                         &x25->facilities,
195                                         &x25->dte_facilities,
196                                         x25->neighbour->global_facil_mask);
197                         dptr    = skb_put(skb, len);
198                         memcpy(dptr, facilities, len);
199                         dptr = skb_put(skb, x25->calluserdata.cudlength);
200                         memcpy(dptr, x25->calluserdata.cuddata,
201                                x25->calluserdata.cudlength);
202                         x25->calluserdata.cudlength = 0;
203                         break;
204 
205                 case X25_CALL_ACCEPTED:
206                         dptr    = skb_put(skb, 2);
207                         *dptr++ = X25_CALL_ACCEPTED;
208                         *dptr++ = 0x00;         /* Address lengths */
209                         len     = x25_create_facilities(facilities,
210                                                         &x25->facilities,
211                                                         &x25->dte_facilities,
212                                                         x25->vc_facil_mask);
213                         dptr    = skb_put(skb, len);
214                         memcpy(dptr, facilities, len);
215 
216                         /* fast select with no restriction on response
217                                 allows call user data. Userland must
218                                 ensure it is ours and not theirs */
219                         if(x25->facilities.reverse & 0x80) {
220                                 dptr = skb_put(skb,
221                                         x25->calluserdata.cudlength);
222                                 memcpy(dptr, x25->calluserdata.cuddata,
223                                        x25->calluserdata.cudlength);
224                         }
225                         x25->calluserdata.cudlength = 0;
226                         break;
227 
228                 case X25_CLEAR_REQUEST:
229                         dptr    = skb_put(skb, 3);
230                         *dptr++ = frametype;
231                         *dptr++ = x25->causediag.cause;
232                         *dptr++ = x25->causediag.diagnostic;
233                         break;
234 
235                 case X25_RESET_REQUEST:
236                         dptr    = skb_put(skb, 3);
237                         *dptr++ = frametype;
238                         *dptr++ = 0x00;         /* XXX */
239                         *dptr++ = 0x00;         /* XXX */
240                         break;
241 
242                 case X25_RR:
243                 case X25_RNR:
244                 case X25_REJ:
245                         if (x25->neighbour->extended) {
246                                 dptr     = skb_put(skb, 2);
247                                 *dptr++  = frametype;
248                                 *dptr++  = (x25->vr << 1) & 0xFE;
249                         } else {
250                                 dptr     = skb_put(skb, 1);
251                                 *dptr    = frametype;
252                                 *dptr++ |= (x25->vr << 5) & 0xE0;
253                         }
254                         break;
255 
256                 case X25_CLEAR_CONFIRMATION:
257                 case X25_INTERRUPT_CONFIRMATION:
258                 case X25_RESET_CONFIRMATION:
259                         dptr  = skb_put(skb, 1);
260                         *dptr = frametype;
261                         break;
262         }
263 
264         x25_transmit_link(skb, x25->neighbour);
265 }
266 
267 /*
268  *      Unpick the contents of the passed X.25 Packet Layer frame.
269  */
270 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
271                int *d, int *m)
272 {
273         struct x25_sock *x25 = x25_sk(sk);
274         unsigned char *frame;
275 
276         if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
277                 return X25_ILLEGAL;
278         frame = skb->data;
279 
280         *ns = *nr = *q = *d = *m = 0;
281 
282         switch (frame[2]) {
283         case X25_CALL_REQUEST:
284         case X25_CALL_ACCEPTED:
285         case X25_CLEAR_REQUEST:
286         case X25_CLEAR_CONFIRMATION:
287         case X25_INTERRUPT:
288         case X25_INTERRUPT_CONFIRMATION:
289         case X25_RESET_REQUEST:
290         case X25_RESET_CONFIRMATION:
291         case X25_RESTART_REQUEST:
292         case X25_RESTART_CONFIRMATION:
293         case X25_REGISTRATION_REQUEST:
294         case X25_REGISTRATION_CONFIRMATION:
295         case X25_DIAGNOSTIC:
296                 return frame[2];
297         }
298 
299         if (x25->neighbour->extended) {
300                 if (frame[2] == X25_RR  ||
301                     frame[2] == X25_RNR ||
302                     frame[2] == X25_REJ) {
303                         if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
304                                 return X25_ILLEGAL;
305                         frame = skb->data;
306 
307                         *nr = (frame[3] >> 1) & 0x7F;
308                         return frame[2];
309                 }
310         } else {
311                 if ((frame[2] & 0x1F) == X25_RR  ||
312                     (frame[2] & 0x1F) == X25_RNR ||
313                     (frame[2] & 0x1F) == X25_REJ) {
314                         *nr = (frame[2] >> 5) & 0x07;
315                         return frame[2] & 0x1F;
316                 }
317         }
318 
319         if (x25->neighbour->extended) {
320                 if ((frame[2] & 0x01) == X25_DATA) {
321                         if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
322                                 return X25_ILLEGAL;
323                         frame = skb->data;
324 
325                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
326                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
327                         *m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
328                         *nr = (frame[3] >> 1) & 0x7F;
329                         *ns = (frame[2] >> 1) & 0x7F;
330                         return X25_DATA;
331                 }
332         } else {
333                 if ((frame[2] & 0x01) == X25_DATA) {
334                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
335                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
336                         *m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
337                         *nr = (frame[2] >> 5) & 0x07;
338                         *ns = (frame[2] >> 1) & 0x07;
339                         return X25_DATA;
340                 }
341         }
342 
343         pr_debug("invalid PLP frame %02X %02X %02X\n",
344                frame[0], frame[1], frame[2]);
345 
346         return X25_ILLEGAL;
347 }
348 
349 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
350                     unsigned char diagnostic)
351 {
352         struct x25_sock *x25 = x25_sk(sk);
353 
354         x25_clear_queues(sk);
355         x25_stop_timer(sk);
356 
357         x25->lci   = 0;
358         x25->state = X25_STATE_0;
359 
360         x25->causediag.cause      = cause;
361         x25->causediag.diagnostic = diagnostic;
362 
363         sk->sk_state     = TCP_CLOSE;
364         sk->sk_err       = reason;
365         sk->sk_shutdown |= SEND_SHUTDOWN;
366 
367         if (!sock_flag(sk, SOCK_DEAD)) {
368                 sk->sk_state_change(sk);
369                 sock_set_flag(sk, SOCK_DEAD);
370         }
371 }
372 
373 /*
374  * Clear an own-rx-busy condition and tell the peer about this, provided
375  * that there is a significant amount of free receive buffer space available.
376  */
377 void x25_check_rbuf(struct sock *sk)
378 {
379         struct x25_sock *x25 = x25_sk(sk);
380 
381         if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
382             (x25->condition & X25_COND_OWN_RX_BUSY)) {
383                 x25->condition &= ~X25_COND_OWN_RX_BUSY;
384                 x25->condition &= ~X25_COND_ACK_PENDING;
385                 x25->vl         = x25->vr;
386                 x25_write_internal(sk, X25_RR);
387                 x25_stop_timer(sk);
388         }
389 }
390 
391 

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