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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Shaun Pereiraebc3f642005-06-22 22:16:17 -070022 * apr/04/15 Shaun Pereira Fast select with no
23 * restriction on response.
Linus Torvalds1da177e2005-04-16 15:20:36 -070024 */
25
26#include <linux/kernel.h>
27#include <linux/string.h>
28#include <linux/skbuff.h>
29#include <net/sock.h>
30#include <net/tcp.h>
31#include <net/x25.h>
32
33/*
34 * This routine purges all of the queues of frames.
35 */
36void x25_clear_queues(struct sock *sk)
37{
38 struct x25_sock *x25 = x25_sk(sk);
39
40 skb_queue_purge(&sk->sk_write_queue);
41 skb_queue_purge(&x25->ack_queue);
42 skb_queue_purge(&x25->interrupt_in_queue);
43 skb_queue_purge(&x25->interrupt_out_queue);
44 skb_queue_purge(&x25->fragment_queue);
45}
46
47
48/*
49 * This routine purges the input queue of those frames that have been
50 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
51 * SDL diagram.
52*/
53void x25_frames_acked(struct sock *sk, unsigned short nr)
54{
55 struct sk_buff *skb;
56 struct x25_sock *x25 = x25_sk(sk);
57 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
58
59 /*
60 * Remove all the ack-ed frames from the ack queue.
61 */
62 if (x25->va != nr)
63 while (skb_peek(&x25->ack_queue) && x25->va != nr) {
64 skb = skb_dequeue(&x25->ack_queue);
65 kfree_skb(skb);
66 x25->va = (x25->va + 1) % modulus;
67 }
68}
69
70void x25_requeue_frames(struct sock *sk)
71{
72 struct sk_buff *skb, *skb_prev = NULL;
73
74 /*
75 * Requeue all the un-ack-ed frames on the output queue to be picked
76 * up by x25_kick. This arrangement handles the possibility of an empty
77 * output queue.
78 */
79 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
80 if (!skb_prev)
81 skb_queue_head(&sk->sk_write_queue, skb);
82 else
83 skb_append(skb_prev, skb);
84 skb_prev = skb;
85 }
86}
87
88/*
89 * Validate that the value of nr is between va and vs. Return true or
90 * false for testing.
91 */
92int x25_validate_nr(struct sock *sk, unsigned short nr)
93{
94 struct x25_sock *x25 = x25_sk(sk);
95 unsigned short vc = x25->va;
96 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
97
98 while (vc != x25->vs) {
99 if (nr == vc)
100 return 1;
101 vc = (vc + 1) % modulus;
102 }
103
104 return nr == x25->vs ? 1 : 0;
105}
106
107/*
108 * This routine is called when the packet layer internally generates a
109 * control frame.
110 */
111void x25_write_internal(struct sock *sk, int frametype)
112{
113 struct x25_sock *x25 = x25_sk(sk);
114 struct sk_buff *skb;
115 unsigned char *dptr;
116 unsigned char facilities[X25_MAX_FAC_LEN];
117 unsigned char addresses[1 + X25_ADDR_LEN];
118 unsigned char lci1, lci2;
119 /*
120 * Default safe frame size.
121 */
122 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
123
124 /*
125 * Adjust frame size.
126 */
127 switch (frametype) {
128 case X25_CALL_REQUEST:
129 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
130 X25_MAX_CUD_LEN;
131 break;
Shaun Pereiraebc3f642005-06-22 22:16:17 -0700132 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 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",
152 frametype);
153 return;
154 }
155
156 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
157 return;
158
159 /*
160 * Space for Ethernet and 802.2 LLC headers.
161 */
162 skb_reserve(skb, X25_MAX_L2_LEN);
163
164 /*
165 * Make space for the GFI and LCI, and fill them in.
166 */
167 dptr = skb_put(skb, 2);
168
169 lci1 = (x25->lci >> 8) & 0x0F;
170 lci2 = (x25->lci >> 0) & 0xFF;
171
172 if (x25->neighbour->extended) {
173 *dptr++ = lci1 | X25_GFI_EXTSEQ;
174 *dptr++ = lci2;
175 } else {
176 *dptr++ = lci1 | X25_GFI_STDSEQ;
177 *dptr++ = lci2;
178 }
179
180 /*
181 * Now fill in the frame type specific information.
182 */
183 switch (frametype) {
184
185 case X25_CALL_REQUEST:
186 dptr = skb_put(skb, 1);
187 *dptr++ = X25_CALL_REQUEST;
188 len = x25_addr_aton(addresses, &x25->dest_addr,
189 &x25->source_addr);
190 dptr = skb_put(skb, len);
191 memcpy(dptr, addresses, len);
192 len = x25_create_facilities(facilities,
193 &x25->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->vc_facil_mask);
210 dptr = skb_put(skb, len);
211 memcpy(dptr, facilities, len);
Shaun Pereiraebc3f642005-06-22 22:16:17 -0700212
213 /* fast select with no restriction on response
214 allows call user data. Userland must
215 ensure it is ours and not theirs */
216 if(x25->facilities.reverse & 0x80) {
217 dptr = skb_put(skb,
218 x25->calluserdata.cudlength);
219 memcpy(dptr, x25->calluserdata.cuddata,
220 x25->calluserdata.cudlength);
221 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 x25->calluserdata.cudlength = 0;
223 break;
224
225 case X25_CLEAR_REQUEST:
226 case X25_RESET_REQUEST:
227 dptr = skb_put(skb, 3);
228 *dptr++ = frametype;
229 *dptr++ = 0x00; /* XXX */
230 *dptr++ = 0x00; /* XXX */
231 break;
232
233 case X25_RR:
234 case X25_RNR:
235 case X25_REJ:
236 if (x25->neighbour->extended) {
237 dptr = skb_put(skb, 2);
238 *dptr++ = frametype;
239 *dptr++ = (x25->vr << 1) & 0xFE;
240 } else {
241 dptr = skb_put(skb, 1);
242 *dptr = frametype;
243 *dptr++ |= (x25->vr << 5) & 0xE0;
244 }
245 break;
246
247 case X25_CLEAR_CONFIRMATION:
248 case X25_INTERRUPT_CONFIRMATION:
249 case X25_RESET_CONFIRMATION:
250 dptr = skb_put(skb, 1);
251 *dptr = frametype;
252 break;
253 }
254
255 x25_transmit_link(skb, x25->neighbour);
256}
257
258/*
259 * Unpick the contents of the passed X.25 Packet Layer frame.
260 */
261int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
262 int *d, int *m)
263{
264 struct x25_sock *x25 = x25_sk(sk);
265 unsigned char *frame = skb->data;
266
267 *ns = *nr = *q = *d = *m = 0;
268
269 switch (frame[2]) {
270 case X25_CALL_REQUEST:
271 case X25_CALL_ACCEPTED:
272 case X25_CLEAR_REQUEST:
273 case X25_CLEAR_CONFIRMATION:
274 case X25_INTERRUPT:
275 case X25_INTERRUPT_CONFIRMATION:
276 case X25_RESET_REQUEST:
277 case X25_RESET_CONFIRMATION:
278 case X25_RESTART_REQUEST:
279 case X25_RESTART_CONFIRMATION:
280 case X25_REGISTRATION_REQUEST:
281 case X25_REGISTRATION_CONFIRMATION:
282 case X25_DIAGNOSTIC:
283 return frame[2];
284 }
285
286 if (x25->neighbour->extended) {
287 if (frame[2] == X25_RR ||
288 frame[2] == X25_RNR ||
289 frame[2] == X25_REJ) {
290 *nr = (frame[3] >> 1) & 0x7F;
291 return frame[2];
292 }
293 } else {
294 if ((frame[2] & 0x1F) == X25_RR ||
295 (frame[2] & 0x1F) == X25_RNR ||
296 (frame[2] & 0x1F) == X25_REJ) {
297 *nr = (frame[2] >> 5) & 0x07;
298 return frame[2] & 0x1F;
299 }
300 }
301
302 if (x25->neighbour->extended) {
303 if ((frame[2] & 0x01) == X25_DATA) {
304 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
305 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
306 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
307 *nr = (frame[3] >> 1) & 0x7F;
308 *ns = (frame[2] >> 1) & 0x7F;
309 return X25_DATA;
310 }
311 } else {
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[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
316 *nr = (frame[2] >> 5) & 0x07;
317 *ns = (frame[2] >> 1) & 0x07;
318 return X25_DATA;
319 }
320 }
321
322 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
323 frame[0], frame[1], frame[2]);
324
325 return X25_ILLEGAL;
326}
327
328void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
329 unsigned char diagnostic)
330{
331 struct x25_sock *x25 = x25_sk(sk);
332
333 x25_clear_queues(sk);
334 x25_stop_timer(sk);
335
336 x25->lci = 0;
337 x25->state = X25_STATE_0;
338
339 x25->causediag.cause = cause;
340 x25->causediag.diagnostic = diagnostic;
341
342 sk->sk_state = TCP_CLOSE;
343 sk->sk_err = reason;
344 sk->sk_shutdown |= SEND_SHUTDOWN;
345
346 if (!sock_flag(sk, SOCK_DEAD)) {
347 sk->sk_state_change(sk);
348 sock_set_flag(sk, SOCK_DEAD);
349 }
350}
351
352/*
353 * Clear an own-rx-busy condition and tell the peer about this, provided
354 * that there is a significant amount of free receive buffer space available.
355 */
356void x25_check_rbuf(struct sock *sk)
357{
358 struct x25_sock *x25 = x25_sk(sk);
359
360 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
361 (x25->condition & X25_COND_OWN_RX_BUSY)) {
362 x25->condition &= ~X25_COND_OWN_RX_BUSY;
363 x25->condition &= ~X25_COND_ACK_PENDING;
364 x25->vl = x25->vr;
365 x25_write_internal(sk, X25_RR);
366 x25_stop_timer(sk);
367 }
368}
369