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 */
x25_clear_queues(struct sock * sk)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 */
x25_frames_acked(struct sock * sk,unsigned short nr)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
x25_requeue_frames(struct sock * sk)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 */
x25_validate_nr(struct sock * sk,unsigned short nr)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 */
x25_write_internal(struct sock * sk,int frametype)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 */
x25_decode(struct sock * sk,struct sk_buff * skb,int * ns,int * nr,int * q,int * d,int * m)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
x25_disconnect(struct sock * sk,int reason,unsigned char cause,unsigned char diagnostic)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 */
x25_check_rbuf(struct sock * sk)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
389