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Linux/net/x25/x25_in.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 code.
 19  *                                        New timer architecture.
 20  *      2000-03-20      Daniela Squassoni Disabling/enabling of facilities
 21  *                                        negotiation.
 22  *      2000-11-10      Henner Eisen      Check and reset for out-of-sequence
 23  *                                        i-frames.
 24  */
 25 
 26 #define pr_fmt(fmt) "X25: " fmt
 27 
 28 #include <linux/slab.h>
 29 #include <linux/errno.h>
 30 #include <linux/kernel.h>
 31 #include <linux/string.h>
 32 #include <linux/skbuff.h>
 33 #include <net/sock.h>
 34 #include <net/tcp_states.h>
 35 #include <net/x25.h>
 36 
 37 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
 38 {
 39         struct sk_buff *skbo, *skbn = skb;
 40         struct x25_sock *x25 = x25_sk(sk);
 41 
 42         if (more) {
 43                 x25->fraglen += skb->len;
 44                 skb_queue_tail(&x25->fragment_queue, skb);
 45                 skb_set_owner_r(skb, sk);
 46                 return 0;
 47         }
 48 
 49         if (!more && x25->fraglen > 0) {        /* End of fragment */
 50                 int len = x25->fraglen + skb->len;
 51 
 52                 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
 53                         kfree_skb(skb);
 54                         return 1;
 55                 }
 56 
 57                 skb_queue_tail(&x25->fragment_queue, skb);
 58 
 59                 skb_reset_transport_header(skbn);
 60 
 61                 skbo = skb_dequeue(&x25->fragment_queue);
 62                 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
 63                                           skbo->len);
 64                 kfree_skb(skbo);
 65 
 66                 while ((skbo =
 67                         skb_dequeue(&x25->fragment_queue)) != NULL) {
 68                         skb_pull(skbo, (x25->neighbour->extended) ?
 69                                         X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
 70                         skb_copy_from_linear_data(skbo,
 71                                                   skb_put(skbn, skbo->len),
 72                                                   skbo->len);
 73                         kfree_skb(skbo);
 74                 }
 75 
 76                 x25->fraglen = 0;
 77         }
 78 
 79         skb_set_owner_r(skbn, sk);
 80         skb_queue_tail(&sk->sk_receive_queue, skbn);
 81         if (!sock_flag(sk, SOCK_DEAD))
 82                 sk->sk_data_ready(sk);
 83 
 84         return 0;
 85 }
 86 
 87 /*
 88  * State machine for state 1, Awaiting Call Accepted State.
 89  * The handling of the timer(s) is in file x25_timer.c.
 90  * Handling of state 0 and connection release is in af_x25.c.
 91  */
 92 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 93 {
 94         struct x25_address source_addr, dest_addr;
 95         int len;
 96         struct x25_sock *x25 = x25_sk(sk);
 97 
 98         switch (frametype) {
 99         case X25_CALL_ACCEPTED: {
100 
101                 x25_stop_timer(sk);
102                 x25->condition = 0x00;
103                 x25->vs        = 0;
104                 x25->va        = 0;
105                 x25->vr        = 0;
106                 x25->vl        = 0;
107                 x25->state     = X25_STATE_3;
108                 sk->sk_state   = TCP_ESTABLISHED;
109                 /*
110                  *      Parse the data in the frame.
111                  */
112                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
113                         goto out_clear;
114                 skb_pull(skb, X25_STD_MIN_LEN);
115 
116                 len = x25_parse_address_block(skb, &source_addr,
117                                               &dest_addr);
118                 if (len > 0)
119                         skb_pull(skb, len);
120                 else if (len < 0)
121                         goto out_clear;
122 
123                 len = x25_parse_facilities(skb, &x25->facilities,
124                                            &x25->dte_facilities,
125                                            &x25->vc_facil_mask);
126                 if (len > 0)
127                         skb_pull(skb, len);
128                 else if (len < 0)
129                         goto out_clear;
130                 /*
131                  *      Copy any Call User Data.
132                  */
133                 if (skb->len > 0) {
134                         if (skb->len > X25_MAX_CUD_LEN)
135                                 goto out_clear;
136 
137                         skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
138                                 skb->len);
139                         x25->calluserdata.cudlength = skb->len;
140                 }
141                 if (!sock_flag(sk, SOCK_DEAD))
142                         sk->sk_state_change(sk);
143                 break;
144         }
145         case X25_CALL_REQUEST:
146                 /* call collision */
147                 x25->causediag.cause      = 0x01;
148                 x25->causediag.diagnostic = 0x48;
149 
150                 x25_write_internal(sk, X25_CLEAR_REQUEST);
151                 x25_disconnect(sk, EISCONN, 0x01, 0x48);
152                 break;
153 
154         case X25_CLEAR_REQUEST:
155                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
156                         goto out_clear;
157 
158                 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
159                 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
160                 break;
161 
162         default:
163                 break;
164         }
165 
166         return 0;
167 
168 out_clear:
169         x25_write_internal(sk, X25_CLEAR_REQUEST);
170         x25->state = X25_STATE_2;
171         x25_start_t23timer(sk);
172         return 0;
173 }
174 
175 /*
176  * State machine for state 2, Awaiting Clear Confirmation State.
177  * The handling of the timer(s) is in file x25_timer.c
178  * Handling of state 0 and connection release is in af_x25.c.
179  */
180 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
181 {
182         switch (frametype) {
183 
184                 case X25_CLEAR_REQUEST:
185                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
186                                 goto out_clear;
187 
188                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
189                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
190                         break;
191 
192                 case X25_CLEAR_CONFIRMATION:
193                         x25_disconnect(sk, 0, 0, 0);
194                         break;
195 
196                 default:
197                         break;
198         }
199 
200         return 0;
201 
202 out_clear:
203         x25_write_internal(sk, X25_CLEAR_REQUEST);
204         x25_start_t23timer(sk);
205         return 0;
206 }
207 
208 /*
209  * State machine for state 3, Connected State.
210  * The handling of the timer(s) is in file x25_timer.c
211  * Handling of state 0 and connection release is in af_x25.c.
212  */
213 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
214 {
215         int queued = 0;
216         int modulus;
217         struct x25_sock *x25 = x25_sk(sk);
218 
219         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
220 
221         switch (frametype) {
222 
223                 case X25_RESET_REQUEST:
224                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
225                         x25_stop_timer(sk);
226                         x25->condition = 0x00;
227                         x25->vs        = 0;
228                         x25->vr        = 0;
229                         x25->va        = 0;
230                         x25->vl        = 0;
231                         x25_requeue_frames(sk);
232                         break;
233 
234                 case X25_CLEAR_REQUEST:
235                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
236                                 goto out_clear;
237 
238                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
239                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
240                         break;
241 
242                 case X25_RR:
243                 case X25_RNR:
244                         if (!x25_validate_nr(sk, nr)) {
245                                 x25_clear_queues(sk);
246                                 x25_write_internal(sk, X25_RESET_REQUEST);
247                                 x25_start_t22timer(sk);
248                                 x25->condition = 0x00;
249                                 x25->vs        = 0;
250                                 x25->vr        = 0;
251                                 x25->va        = 0;
252                                 x25->vl        = 0;
253                                 x25->state     = X25_STATE_4;
254                         } else {
255                                 x25_frames_acked(sk, nr);
256                                 if (frametype == X25_RNR) {
257                                         x25->condition |= X25_COND_PEER_RX_BUSY;
258                                 } else {
259                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
260                                 }
261                         }
262                         break;
263 
264                 case X25_DATA:  /* XXX */
265                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
266                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
267                                 x25_clear_queues(sk);
268                                 x25_write_internal(sk, X25_RESET_REQUEST);
269                                 x25_start_t22timer(sk);
270                                 x25->condition = 0x00;
271                                 x25->vs        = 0;
272                                 x25->vr        = 0;
273                                 x25->va        = 0;
274                                 x25->vl        = 0;
275                                 x25->state     = X25_STATE_4;
276                                 break;
277                         }
278                         x25_frames_acked(sk, nr);
279                         if (ns == x25->vr) {
280                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
281                                         x25->vr = (x25->vr + 1) % modulus;
282                                         queued = 1;
283                                 } else {
284                                         /* Should never happen */
285                                         x25_clear_queues(sk);
286                                         x25_write_internal(sk, X25_RESET_REQUEST);
287                                         x25_start_t22timer(sk);
288                                         x25->condition = 0x00;
289                                         x25->vs        = 0;
290                                         x25->vr        = 0;
291                                         x25->va        = 0;
292                                         x25->vl        = 0;
293                                         x25->state     = X25_STATE_4;
294                                         break;
295                                 }
296                                 if (atomic_read(&sk->sk_rmem_alloc) >
297                                     (sk->sk_rcvbuf >> 1))
298                                         x25->condition |= X25_COND_OWN_RX_BUSY;
299                         }
300                         /*
301                          *      If the window is full Ack it immediately, else
302                          *      start the holdback timer.
303                          */
304                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
305                                 x25->condition &= ~X25_COND_ACK_PENDING;
306                                 x25_stop_timer(sk);
307                                 x25_enquiry_response(sk);
308                         } else {
309                                 x25->condition |= X25_COND_ACK_PENDING;
310                                 x25_start_t2timer(sk);
311                         }
312                         break;
313 
314                 case X25_INTERRUPT_CONFIRMATION:
315                         clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
316                         break;
317 
318                 case X25_INTERRUPT:
319                         if (sock_flag(sk, SOCK_URGINLINE))
320                                 queued = !sock_queue_rcv_skb(sk, skb);
321                         else {
322                                 skb_set_owner_r(skb, sk);
323                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
324                                 queued = 1;
325                         }
326                         sk_send_sigurg(sk);
327                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
328                         break;
329 
330                 default:
331                         pr_warn("unknown %02X in state 3\n", frametype);
332                         break;
333         }
334 
335         return queued;
336 
337 out_clear:
338         x25_write_internal(sk, X25_CLEAR_REQUEST);
339         x25->state = X25_STATE_2;
340         x25_start_t23timer(sk);
341         return 0;
342 }
343 
344 /*
345  * State machine for state 4, Awaiting Reset Confirmation State.
346  * The handling of the timer(s) is in file x25_timer.c
347  * Handling of state 0 and connection release is in af_x25.c.
348  */
349 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
350 {
351         struct x25_sock *x25 = x25_sk(sk);
352 
353         switch (frametype) {
354 
355                 case X25_RESET_REQUEST:
356                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
357                         /* fall through */
358                 case X25_RESET_CONFIRMATION: {
359                         x25_stop_timer(sk);
360                         x25->condition = 0x00;
361                         x25->va        = 0;
362                         x25->vr        = 0;
363                         x25->vs        = 0;
364                         x25->vl        = 0;
365                         x25->state     = X25_STATE_3;
366                         x25_requeue_frames(sk);
367                         break;
368                 }
369                 case X25_CLEAR_REQUEST:
370                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
371                                 goto out_clear;
372 
373                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
374                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
375                         break;
376 
377                 default:
378                         break;
379         }
380 
381         return 0;
382 
383 out_clear:
384         x25_write_internal(sk, X25_CLEAR_REQUEST);
385         x25->state = X25_STATE_2;
386         x25_start_t23timer(sk);
387         return 0;
388 }
389 
390 /* Higher level upcall for a LAPB frame */
391 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
392 {
393         struct x25_sock *x25 = x25_sk(sk);
394         int queued = 0, frametype, ns, nr, q, d, m;
395 
396         if (x25->state == X25_STATE_0)
397                 return 0;
398 
399         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
400 
401         switch (x25->state) {
402         case X25_STATE_1:
403                 queued = x25_state1_machine(sk, skb, frametype);
404                 break;
405         case X25_STATE_2:
406                 queued = x25_state2_machine(sk, skb, frametype);
407                 break;
408         case X25_STATE_3:
409                 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
410                 break;
411         case X25_STATE_4:
412                 queued = x25_state4_machine(sk, skb, frametype);
413                 break;
414         }
415 
416         x25_kick(sk);
417 
418         return queued;
419 }
420 
421 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
422 {
423         int queued = x25_process_rx_frame(sk, skb);
424 
425         if (!queued)
426                 kfree_skb(skb);
427 
428         return 0;
429 }
430 

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