File: /usr/src/linux/net/x25/x25_subr.c
1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine, randomly fail to work with new
5 * releases, misbehave and/or generally screw up. It might even work.
6 *
7 * This code REQUIRES 2.1.15 or higher
8 *
9 * This module:
10 * This module is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * History
16 * X.25 001 Jonathan Naylor Started coding.
17 * X.25 002 Jonathan Naylor Centralised disconnection processing.
18 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
19 * negotiation.
20 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
21 */
22
23 #include <linux/errno.h>
24 #include <linux/types.h>
25 #include <linux/socket.h>
26 #include <linux/in.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/timer.h>
30 #include <linux/string.h>
31 #include <linux/sockios.h>
32 #include <linux/net.h>
33 #include <linux/inet.h>
34 #include <linux/netdevice.h>
35 #include <linux/skbuff.h>
36 #include <net/sock.h>
37 #include <asm/segment.h>
38 #include <asm/system.h>
39 #include <linux/fcntl.h>
40 #include <linux/mm.h>
41 #include <linux/interrupt.h>
42 #include <net/x25.h>
43
44 /*
45 * This routine purges all of the queues of frames.
46 */
47 void x25_clear_queues(struct sock *sk)
48 {
49 skb_queue_purge(&sk->write_queue);
50 skb_queue_purge(&sk->protinfo.x25->ack_queue);
51 skb_queue_purge(&sk->protinfo.x25->interrupt_in_queue);
52 skb_queue_purge(&sk->protinfo.x25->interrupt_out_queue);
53 skb_queue_purge(&sk->protinfo.x25->fragment_queue);
54 }
55
56
57 /*
58 * This routine purges the input queue of those frames that have been
59 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
60 * SDL diagram.
61 */
62 void x25_frames_acked(struct sock *sk, unsigned short nr)
63 {
64 struct sk_buff *skb;
65 int modulus = sk->protinfo.x25->neighbour->extended ? X25_EMODULUS :
66 X25_SMODULUS;
67
68 /*
69 * Remove all the ack-ed frames from the ack queue.
70 */
71 if (sk->protinfo.x25->va != nr)
72 while (skb_peek(&sk->protinfo.x25->ack_queue) != NULL &&
73 sk->protinfo.x25->va != nr) {
74 skb = skb_dequeue(&sk->protinfo.x25->ack_queue);
75 kfree_skb(skb);
76 sk->protinfo.x25->va = (sk->protinfo.x25->va + 1) %
77 modulus;
78 }
79 }
80
81 void x25_requeue_frames(struct sock *sk)
82 {
83 struct sk_buff *skb, *skb_prev = NULL;
84
85 /*
86 * Requeue all the un-ack-ed frames on the output queue to be picked
87 * up by x25_kick. This arrangement handles the possibility of an empty
88 * output queue.
89 */
90 while ((skb = skb_dequeue(&sk->protinfo.x25->ack_queue)) != NULL) {
91 if (skb_prev == NULL)
92 skb_queue_head(&sk->write_queue, skb);
93 else
94 skb_append(skb_prev, skb);
95 skb_prev = skb;
96 }
97 }
98
99 /*
100 * Validate that the value of nr is between va and vs. Return true or
101 * false for testing.
102 */
103 int x25_validate_nr(struct sock *sk, unsigned short nr)
104 {
105 unsigned short vc = sk->protinfo.x25->va;
106 int modulus = sk->protinfo.x25->neighbour->extended ? X25_EMODULUS :
107 X25_SMODULUS;
108
109 while (vc != sk->protinfo.x25->vs) {
110 if (nr == vc) return 1;
111 vc = (vc + 1) % modulus;
112 }
113
114 return nr == sk->protinfo.x25->vs ? 1 : 0;
115 }
116
117 /*
118 * This routine is called when the packet layer internally generates a
119 * control frame.
120 */
121 void x25_write_internal(struct sock *sk, int frametype)
122 {
123 struct sk_buff *skb;
124 unsigned char *dptr;
125 unsigned char facilities[X25_MAX_FAC_LEN];
126 unsigned char addresses[1 + X25_ADDR_LEN];
127 unsigned char lci1, lci2;
128 int len;
129
130 /*
131 * Default safe frame size.
132 */
133 len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
134
135 /*
136 * Adjust frame size.
137 */
138 switch (frametype) {
139 case X25_CALL_REQUEST:
140 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
141 X25_MAX_CUD_LEN;
142 break;
143 case X25_CALL_ACCEPTED:
144 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
145 break;
146 case X25_CLEAR_REQUEST:
147 case X25_RESET_REQUEST:
148 len += 2;
149 break;
150 case X25_RR:
151 case X25_RNR:
152 case X25_REJ:
153 case X25_CLEAR_CONFIRMATION:
154 case X25_INTERRUPT_CONFIRMATION:
155 case X25_RESET_CONFIRMATION:
156 break;
157 default:
158 printk(KERN_ERR "X.25: invalid frame type %02X\n",
159 frametype);
160 return;
161 }
162
163 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
164 return;
165
166 /*
167 * Space for Ethernet and 802.2 LLC headers.
168 */
169 skb_reserve(skb, X25_MAX_L2_LEN);
170
171 /*
172 * Make space for the GFI and LCI, and fill them in.
173 */
174 dptr = skb_put(skb, 2);
175
176 lci1 = (sk->protinfo.x25->lci >> 8) & 0x0F;
177 lci2 = (sk->protinfo.x25->lci >> 0) & 0xFF;
178
179 if (sk->protinfo.x25->neighbour->extended) {
180 *dptr++ = lci1 | X25_GFI_EXTSEQ;
181 *dptr++ = lci2;
182 } else {
183 *dptr++ = lci1 | X25_GFI_STDSEQ;
184 *dptr++ = lci2;
185 }
186
187 /*
188 * Now fill in the frame type specific information.
189 */
190 switch (frametype) {
191
192 case X25_CALL_REQUEST:
193 dptr = skb_put(skb, 1);
194 *dptr++ = X25_CALL_REQUEST;
195 len = x25_addr_aton(addresses, &sk->protinfo.x25->dest_addr, &sk->protinfo.x25->source_addr);
196 dptr = skb_put(skb, len);
197 memcpy(dptr, addresses, len);
198 len = x25_create_facilities(facilities, &sk->protinfo.x25->facilities, sk->protinfo.x25->neighbour->global_facil_mask);
199 dptr = skb_put(skb, len);
200 memcpy(dptr, facilities, len);
201 dptr = skb_put(skb, sk->protinfo.x25->calluserdata.cudlength);
202 memcpy(dptr, sk->protinfo.x25->calluserdata.cuddata, sk->protinfo.x25->calluserdata.cudlength);
203 sk->protinfo.x25->calluserdata.cudlength = 0;
204 break;
205
206 case X25_CALL_ACCEPTED:
207 dptr = skb_put(skb, 2);
208 *dptr++ = X25_CALL_ACCEPTED;
209 *dptr++ = 0x00; /* Address lengths */
210 len = x25_create_facilities(facilities, &sk->protinfo.x25->facilities, sk->protinfo.x25->vc_facil_mask);
211 dptr = skb_put(skb, len);
212 memcpy(dptr, facilities, len);
213 dptr = skb_put(skb, sk->protinfo.x25->calluserdata.cudlength);
214 memcpy(dptr, sk->protinfo.x25->calluserdata.cuddata, sk->protinfo.x25->calluserdata.cudlength);
215 sk->protinfo.x25->calluserdata.cudlength = 0;
216 break;
217
218 case X25_CLEAR_REQUEST:
219 case X25_RESET_REQUEST:
220 dptr = skb_put(skb, 3);
221 *dptr++ = frametype;
222 *dptr++ = 0x00; /* XXX */
223 *dptr++ = 0x00; /* XXX */
224 break;
225
226 case X25_RR:
227 case X25_RNR:
228 case X25_REJ:
229 if (sk->protinfo.x25->neighbour->extended) {
230 dptr = skb_put(skb, 2);
231 *dptr++ = frametype;
232 *dptr++ = (sk->protinfo.x25->vr << 1) & 0xFE;
233 } else {
234 dptr = skb_put(skb, 1);
235 *dptr = frametype;
236 *dptr++ |= (sk->protinfo.x25->vr << 5) & 0xE0;
237 }
238 break;
239
240 case X25_CLEAR_CONFIRMATION:
241 case X25_INTERRUPT_CONFIRMATION:
242 case X25_RESET_CONFIRMATION:
243 dptr = skb_put(skb, 1);
244 *dptr = frametype;
245 break;
246 }
247
248 x25_transmit_link(skb, sk->protinfo.x25->neighbour);
249 }
250
251 /*
252 * Unpick the contents of the passed X.25 Packet Layer frame.
253 */
254 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
255 int *d, int *m)
256 {
257 unsigned char *frame = skb->data;
258
259 *ns = *nr = *q = *d = *m = 0;
260
261 switch (frame[2]) {
262 case X25_CALL_REQUEST:
263 case X25_CALL_ACCEPTED:
264 case X25_CLEAR_REQUEST:
265 case X25_CLEAR_CONFIRMATION:
266 case X25_INTERRUPT:
267 case X25_INTERRUPT_CONFIRMATION:
268 case X25_RESET_REQUEST:
269 case X25_RESET_CONFIRMATION:
270 case X25_RESTART_REQUEST:
271 case X25_RESTART_CONFIRMATION:
272 case X25_REGISTRATION_REQUEST:
273 case X25_REGISTRATION_CONFIRMATION:
274 case X25_DIAGNOSTIC:
275 return frame[2];
276 }
277
278 if (sk->protinfo.x25->neighbour->extended) {
279 if (frame[2] == X25_RR ||
280 frame[2] == X25_RNR ||
281 frame[2] == X25_REJ) {
282 *nr = (frame[3] >> 1) & 0x7F;
283 return frame[2];
284 }
285 } else {
286 if ((frame[2] & 0x1F) == X25_RR ||
287 (frame[2] & 0x1F) == X25_RNR ||
288 (frame[2] & 0x1F) == X25_REJ) {
289 *nr = (frame[2] >> 5) & 0x07;
290 return frame[2] & 0x1F;
291 }
292 }
293
294 if (sk->protinfo.x25->neighbour->extended) {
295 if ((frame[2] & 0x01) == X25_DATA) {
296 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
297 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
298 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
299 *nr = (frame[3] >> 1) & 0x7F;
300 *ns = (frame[2] >> 1) & 0x7F;
301 return X25_DATA;
302 }
303 } else {
304 if ((frame[2] & 0x01) == X25_DATA) {
305 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
306 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
307 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
308 *nr = (frame[2] >> 5) & 0x07;
309 *ns = (frame[2] >> 1) & 0x07;
310 return X25_DATA;
311 }
312 }
313
314 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
315 frame[0], frame[1], frame[2]);
316
317 return X25_ILLEGAL;
318 }
319
320 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
321 unsigned char diagnostic)
322 {
323 x25_clear_queues(sk);
324 x25_stop_timer(sk);
325
326 sk->protinfo.x25->lci = 0;
327 sk->protinfo.x25->state = X25_STATE_0;
328
329 sk->protinfo.x25->causediag.cause = cause;
330 sk->protinfo.x25->causediag.diagnostic = diagnostic;
331
332 sk->state = TCP_CLOSE;
333 sk->err = reason;
334 sk->shutdown |= SEND_SHUTDOWN;
335
336 if (!sk->dead)
337 sk->state_change(sk);
338
339 sk->dead = 1;
340 }
341
342 /*
343 * Clear an own-rx-busy condition and tell the peer about this, provided
344 * that there is a significant amount of free receive buffer space available.
345 */
346 void x25_check_rbuf(struct sock *sk)
347 {
348 if (atomic_read(&sk->rmem_alloc) < (sk->rcvbuf / 2) &&
349 (sk->protinfo.x25->condition & X25_COND_OWN_RX_BUSY)) {
350 sk->protinfo.x25->condition &= ~X25_COND_OWN_RX_BUSY;
351 sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
352 sk->protinfo.x25->vl = sk->protinfo.x25->vr;
353 x25_write_internal(sk, X25_RR);
354 x25_stop_timer(sk);
355 }
356 }
357