xref: /linux/net/x25/x25_in.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15)
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 code.
19  *					  New timer architecture.
20  *	2000-03-20	Daniela Squassoni Disabling/enabling of facilities
21  *					  negotiation.
22  *	2000-11-10	Henner Eisen	  Check and reset for out-of-sequence
23  *					  i-frames.
24  */
25 
26 #include <linux/errno.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 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
35 {
36 	struct sk_buff *skbo, *skbn = skb;
37 	struct x25_sock *x25 = x25_sk(sk);
38 
39 	if (more) {
40 		x25->fraglen += skb->len;
41 		skb_queue_tail(&x25->fragment_queue, skb);
42 		skb_set_owner_r(skb, sk);
43 		return 0;
44 	}
45 
46 	if (!more && x25->fraglen > 0) {	/* End of fragment */
47 		int len = x25->fraglen + skb->len;
48 
49 		if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
50 			kfree_skb(skb);
51 			return 1;
52 		}
53 
54 		skb_queue_tail(&x25->fragment_queue, skb);
55 
56 		skbn->h.raw = skbn->data;
57 
58 		skbo = skb_dequeue(&x25->fragment_queue);
59 		memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
60 		kfree_skb(skbo);
61 
62 		while ((skbo =
63 			skb_dequeue(&x25->fragment_queue)) != NULL) {
64 			skb_pull(skbo, (x25->neighbour->extended) ?
65 					X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
66 			memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
67 			kfree_skb(skbo);
68 		}
69 
70 		x25->fraglen = 0;
71 	}
72 
73 	skb_set_owner_r(skbn, sk);
74 	skb_queue_tail(&sk->sk_receive_queue, skbn);
75 	if (!sock_flag(sk, SOCK_DEAD))
76 		sk->sk_data_ready(sk, skbn->len);
77 
78 	return 0;
79 }
80 
81 /*
82  * State machine for state 1, Awaiting Call Accepted State.
83  * The handling of the timer(s) is in file x25_timer.c.
84  * Handling of state 0 and connection release is in af_x25.c.
85  */
86 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
87 {
88 	struct x25_address source_addr, dest_addr;
89 
90 	switch (frametype) {
91 		case X25_CALL_ACCEPTED: {
92 			struct x25_sock *x25 = x25_sk(sk);
93 
94 			x25_stop_timer(sk);
95 			x25->condition = 0x00;
96 			x25->vs        = 0;
97 			x25->va        = 0;
98 			x25->vr        = 0;
99 			x25->vl        = 0;
100 			x25->state     = X25_STATE_3;
101 			sk->sk_state   = TCP_ESTABLISHED;
102 			/*
103 			 *	Parse the data in the frame.
104 			 */
105 			skb_pull(skb, X25_STD_MIN_LEN);
106 			skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
107 			skb_pull(skb,
108 				 x25_parse_facilities(skb, &x25->facilities,
109 						&x25->dte_facilities,
110 						&x25->vc_facil_mask));
111 			/*
112 			 *	Copy any Call User Data.
113 			 */
114 			if (skb->len >= 0) {
115 				memcpy(x25->calluserdata.cuddata, skb->data,
116 				       skb->len);
117 				x25->calluserdata.cudlength = skb->len;
118 			}
119 			if (!sock_flag(sk, SOCK_DEAD))
120 				sk->sk_state_change(sk);
121 			break;
122 		}
123 		case X25_CLEAR_REQUEST:
124 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
125 			x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
126 			break;
127 
128 		default:
129 			break;
130 	}
131 
132 	return 0;
133 }
134 
135 /*
136  * State machine for state 2, Awaiting Clear Confirmation State.
137  * The handling of the timer(s) is in file x25_timer.c
138  * Handling of state 0 and connection release is in af_x25.c.
139  */
140 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
141 {
142 	switch (frametype) {
143 
144 		case X25_CLEAR_REQUEST:
145 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
146 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
147 			break;
148 
149 		case X25_CLEAR_CONFIRMATION:
150 			x25_disconnect(sk, 0, 0, 0);
151 			break;
152 
153 		default:
154 			break;
155 	}
156 
157 	return 0;
158 }
159 
160 /*
161  * State machine for state 3, Connected State.
162  * The handling of the timer(s) is in file x25_timer.c
163  * Handling of state 0 and connection release is in af_x25.c.
164  */
165 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
166 {
167 	int queued = 0;
168 	int modulus;
169 	struct x25_sock *x25 = x25_sk(sk);
170 
171 	modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
172 
173 	switch (frametype) {
174 
175 		case X25_RESET_REQUEST:
176 			x25_write_internal(sk, X25_RESET_CONFIRMATION);
177 			x25_stop_timer(sk);
178 			x25->condition = 0x00;
179 			x25->vs        = 0;
180 			x25->vr        = 0;
181 			x25->va        = 0;
182 			x25->vl        = 0;
183 			x25_requeue_frames(sk);
184 			break;
185 
186 		case X25_CLEAR_REQUEST:
187 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
188 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
189 			break;
190 
191 		case X25_RR:
192 		case X25_RNR:
193 			if (!x25_validate_nr(sk, nr)) {
194 				x25_clear_queues(sk);
195 				x25_write_internal(sk, X25_RESET_REQUEST);
196 				x25_start_t22timer(sk);
197 				x25->condition = 0x00;
198 				x25->vs        = 0;
199 				x25->vr        = 0;
200 				x25->va        = 0;
201 				x25->vl        = 0;
202 				x25->state     = X25_STATE_4;
203 			} else {
204 				x25_frames_acked(sk, nr);
205 				if (frametype == X25_RNR) {
206 					x25->condition |= X25_COND_PEER_RX_BUSY;
207 				} else {
208 					x25->condition &= ~X25_COND_PEER_RX_BUSY;
209 				}
210 			}
211 			break;
212 
213 		case X25_DATA:	/* XXX */
214 			x25->condition &= ~X25_COND_PEER_RX_BUSY;
215 			if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
216 				x25_clear_queues(sk);
217 				x25_write_internal(sk, X25_RESET_REQUEST);
218 				x25_start_t22timer(sk);
219 				x25->condition = 0x00;
220 				x25->vs        = 0;
221 				x25->vr        = 0;
222 				x25->va        = 0;
223 				x25->vl        = 0;
224 				x25->state     = X25_STATE_4;
225 				break;
226 			}
227 			x25_frames_acked(sk, nr);
228 			if (ns == x25->vr) {
229 				if (x25_queue_rx_frame(sk, skb, m) == 0) {
230 					x25->vr = (x25->vr + 1) % modulus;
231 					queued = 1;
232 				} else {
233 					/* Should never happen */
234 					x25_clear_queues(sk);
235 					x25_write_internal(sk, X25_RESET_REQUEST);
236 					x25_start_t22timer(sk);
237 					x25->condition = 0x00;
238 					x25->vs        = 0;
239 					x25->vr        = 0;
240 					x25->va        = 0;
241 					x25->vl        = 0;
242 					x25->state     = X25_STATE_4;
243 					break;
244 				}
245 				if (atomic_read(&sk->sk_rmem_alloc) >
246 				    (sk->sk_rcvbuf / 2))
247 					x25->condition |= X25_COND_OWN_RX_BUSY;
248 			}
249 			/*
250 			 *	If the window is full Ack it immediately, else
251 			 *	start the holdback timer.
252 			 */
253 			if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
254 				x25->condition &= ~X25_COND_ACK_PENDING;
255 				x25_stop_timer(sk);
256 				x25_enquiry_response(sk);
257 			} else {
258 				x25->condition |= X25_COND_ACK_PENDING;
259 				x25_start_t2timer(sk);
260 			}
261 			break;
262 
263 		case X25_INTERRUPT_CONFIRMATION:
264 			x25->intflag = 0;
265 			break;
266 
267 		case X25_INTERRUPT:
268 			if (sock_flag(sk, SOCK_URGINLINE))
269 				queued = !sock_queue_rcv_skb(sk, skb);
270 			else {
271 				skb_set_owner_r(skb, sk);
272 				skb_queue_tail(&x25->interrupt_in_queue, skb);
273 				queued = 1;
274 			}
275 			sk_send_sigurg(sk);
276 			x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
277 			break;
278 
279 		default:
280 			printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
281 			break;
282 	}
283 
284 	return queued;
285 }
286 
287 /*
288  * State machine for state 4, Awaiting Reset Confirmation State.
289  * The handling of the timer(s) is in file x25_timer.c
290  * Handling of state 0 and connection release is in af_x25.c.
291  */
292 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
293 {
294 	switch (frametype) {
295 
296 		case X25_RESET_REQUEST:
297 			x25_write_internal(sk, X25_RESET_CONFIRMATION);
298 		case X25_RESET_CONFIRMATION: {
299 			struct x25_sock *x25 = x25_sk(sk);
300 
301 			x25_stop_timer(sk);
302 			x25->condition = 0x00;
303 			x25->va        = 0;
304 			x25->vr        = 0;
305 			x25->vs        = 0;
306 			x25->vl        = 0;
307 			x25->state     = X25_STATE_3;
308 			x25_requeue_frames(sk);
309 			break;
310 		}
311 		case X25_CLEAR_REQUEST:
312 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
313 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
314 			break;
315 
316 		default:
317 			break;
318 	}
319 
320 	return 0;
321 }
322 
323 /* Higher level upcall for a LAPB frame */
324 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
325 {
326 	struct x25_sock *x25 = x25_sk(sk);
327 	int queued = 0, frametype, ns, nr, q, d, m;
328 
329 	if (x25->state == X25_STATE_0)
330 		return 0;
331 
332 	frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
333 
334 	switch (x25->state) {
335 		case X25_STATE_1:
336 			queued = x25_state1_machine(sk, skb, frametype);
337 			break;
338 		case X25_STATE_2:
339 			queued = x25_state2_machine(sk, skb, frametype);
340 			break;
341 		case X25_STATE_3:
342 			queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
343 			break;
344 		case X25_STATE_4:
345 			queued = x25_state4_machine(sk, skb, frametype);
346 			break;
347 	}
348 
349 	x25_kick(sk);
350 
351 	return queued;
352 }
353 
354 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
355 {
356 	int queued = x25_process_rx_frame(sk, skb);
357 
358 	if (!queued)
359 		kfree_skb(skb);
360 
361 	return 0;
362 }
363