xref: /openbmc/linux/net/x25/x25_subr.c (revision 4800cd83)
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  */
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 */
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 
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  */
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  */
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  */
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 
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  */
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