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

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