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 +
131 X25_MAX_CUD_LEN;
132 break;
133 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
134 if(x25->facilities.reverse & 0x80) {
135 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
136 } else {
137 len += 1 + X25_MAX_FAC_LEN;
138 }
139 break;
140 case X25_CLEAR_REQUEST:
141 case X25_RESET_REQUEST:
142 len += 2;
143 break;
144 case X25_RR:
145 case X25_RNR:
146 case X25_REJ:
147 case X25_CLEAR_CONFIRMATION:
148 case X25_INTERRUPT_CONFIRMATION:
149 case X25_RESET_CONFIRMATION:
150 break;
151 default:
152 printk(KERN_ERR "X.25: invalid frame type %02X\n",
153 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 */
x25_decode(struct sock * sk,struct sk_buff * skb,int * ns,int * nr,int * q,int * d,int * m)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 = skb->data;
275
276 *ns = *nr = *q = *d = *m = 0;
277
278 switch (frame[2]) {
279 case X25_CALL_REQUEST:
280 case X25_CALL_ACCEPTED:
281 case X25_CLEAR_REQUEST:
282 case X25_CLEAR_CONFIRMATION:
283 case X25_INTERRUPT:
284 case X25_INTERRUPT_CONFIRMATION:
285 case X25_RESET_REQUEST:
286 case X25_RESET_CONFIRMATION:
287 case X25_RESTART_REQUEST:
288 case X25_RESTART_CONFIRMATION:
289 case X25_REGISTRATION_REQUEST:
290 case X25_REGISTRATION_CONFIRMATION:
291 case X25_DIAGNOSTIC:
292 return frame[2];
293 }
294
295 if (x25->neighbour->extended) {
296 if (frame[2] == X25_RR ||
297 frame[2] == X25_RNR ||
298 frame[2] == X25_REJ) {
299 *nr = (frame[3] >> 1) & 0x7F;
300 return frame[2];
301 }
302 } else {
303 if ((frame[2] & 0x1F) == X25_RR ||
304 (frame[2] & 0x1F) == X25_RNR ||
305 (frame[2] & 0x1F) == X25_REJ) {
306 *nr = (frame[2] >> 5) & 0x07;
307 return frame[2] & 0x1F;
308 }
309 }
310
311 if (x25->neighbour->extended) {
312 if ((frame[2] & 0x01) == X25_DATA) {
313 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
314 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
315 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
316 *nr = (frame[3] >> 1) & 0x7F;
317 *ns = (frame[2] >> 1) & 0x7F;
318 return X25_DATA;
319 }
320 } else {
321 if ((frame[2] & 0x01) == X25_DATA) {
322 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
323 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
324 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
325 *nr = (frame[2] >> 5) & 0x07;
326 *ns = (frame[2] >> 1) & 0x07;
327 return X25_DATA;
328 }
329 }
330
331 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
332 frame[0], frame[1], frame[2]);
333
334 return X25_ILLEGAL;
335 }
336
x25_disconnect(struct sock * sk,int reason,unsigned char cause,unsigned char diagnostic)337 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
338 unsigned char diagnostic)
339 {
340 struct x25_sock *x25 = x25_sk(sk);
341
342 x25_clear_queues(sk);
343 x25_stop_timer(sk);
344
345 x25->lci = 0;
346 x25->state = X25_STATE_0;
347
348 x25->causediag.cause = cause;
349 x25->causediag.diagnostic = diagnostic;
350
351 sk->sk_state = TCP_CLOSE;
352 sk->sk_err = reason;
353 sk->sk_shutdown |= SEND_SHUTDOWN;
354
355 if (!sock_flag(sk, SOCK_DEAD)) {
356 sk->sk_state_change(sk);
357 sock_set_flag(sk, SOCK_DEAD);
358 }
359 }
360
361 /*
362 * Clear an own-rx-busy condition and tell the peer about this, provided
363 * that there is a significant amount of free receive buffer space available.
364 */
x25_check_rbuf(struct sock * sk)365 void x25_check_rbuf(struct sock *sk)
366 {
367 struct x25_sock *x25 = x25_sk(sk);
368
369 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
370 (x25->condition & X25_COND_OWN_RX_BUSY)) {
371 x25->condition &= ~X25_COND_OWN_RX_BUSY;
372 x25->condition &= ~X25_COND_ACK_PENDING;
373 x25->vl = x25->vr;
374 x25_write_internal(sk, X25_RR);
375 x25_stop_timer(sk);
376 }
377 }
378
379