summaryrefslogtreecommitdiffstats
path: root/net/netrom/nr_in.c
blob: c13e92666174e6679aaa59d0afc23c60d9206296 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
/*
 *	NET/ROM release 006
 *
 *	This code REQUIRES 2.1.15 or higher/ NET3.038
 *
 *	This module:
 *		This module is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 *	Most of this code is based on the SDL diagrams published in the 7th
 *	ARRL Computer Networking Conference papers. The diagrams have mistakes
 *	in them, but are mostly correct. Before you modify the code could you
 *	read the SDL diagrams as the code is not obvious and probably very
 *	easy to break;
 *
 *	History
 *	NET/ROM 001	Jonathan(G4KLX)	Cloned from ax25_in.c
 *	NET/ROM 003	Jonathan(G4KLX)	Added NET/ROM fragment reception.
 *			Darryl(G7LED)	Added missing INFO with NAK case, optimized
 *					INFOACK handling, removed reconnect on error.
 *	NET/ROM 006	Jonathan(G4KLX)	Hdrincl removal changes.
 */

#include <linux/config.h>
#if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/ip.h>			/* For ip_rcv */
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/netrom.h>

static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
{
	struct sk_buff *skbo, *skbn = skb;

	skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);

	if (more) {
		sk->protinfo.nr->fraglen += skb->len;
		skb_queue_tail(&sk->protinfo.nr->frag_queue, skb);
		return 0;
	}

	if (!more && sk->protinfo.nr->fraglen > 0) {	/* End of fragment */
		sk->protinfo.nr->fraglen += skb->len;
		skb_queue_tail(&sk->protinfo.nr->frag_queue, skb);

		if ((skbn = alloc_skb(sk->protinfo.nr->fraglen, GFP_ATOMIC)) == NULL)
			return 1;

		skbn->h.raw = skbn->data;

		while ((skbo = skb_dequeue(&sk->protinfo.nr->frag_queue)) != NULL) {
			memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
			kfree_skb(skbo, FREE_READ);
		}

		sk->protinfo.nr->fraglen = 0;		
	}

	return sock_queue_rcv_skb(sk, skbn);
}

/*
 * State machine for state 1, Awaiting Connection State.
 * The handling of the timer(s) is in file nr_timer.c.
 * Handling of state 0 and connection release is in netrom.c.
 */
static int nr_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	switch (frametype) {

		case NR_CONNACK:
			sk->protinfo.nr->your_index = skb->data[17];
			sk->protinfo.nr->your_id    = skb->data[18];
			sk->protinfo.nr->t1timer    = 0;
			sk->protinfo.nr->t2timer    = 0;
			sk->protinfo.nr->t4timer    = 0;
			sk->protinfo.nr->vs         = 0;
			sk->protinfo.nr->va         = 0;
			sk->protinfo.nr->vr         = 0;
			sk->protinfo.nr->vl	    = 0;
			sk->protinfo.nr->state      = NR_STATE_3;
			sk->protinfo.nr->n2count    = 0;
			sk->protinfo.nr->window     = skb->data[20];
			sk->state                   = TCP_ESTABLISHED;
			/* For WAIT_SABM connections we will produce an accept ready socket here */
			if (!sk->dead)
				sk->state_change(sk);
			break;

		case NR_CONNACK | NR_CHOKE_FLAG:
			nr_clear_queues(sk);
			sk->protinfo.nr->state = NR_STATE_0;
			sk->state              = TCP_CLOSE;
			sk->err                = ECONNREFUSED;
			sk->shutdown          |= SEND_SHUTDOWN;
			if (!sk->dead)
				sk->state_change(sk);
			sk->dead               = 1;
			break;

		default:
			break;
	}

	return 0;
}

/*
 * State machine for state 2, Awaiting Release State.
 * The handling of the timer(s) is in file nr_timer.c
 * Handling of state 0 and connection release is in netrom.c.
 */
static int nr_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	switch (frametype) {

		case NR_DISCREQ:
			nr_write_internal(sk, NR_DISCACK);

		case NR_DISCACK:
			sk->protinfo.nr->state = NR_STATE_0;
			sk->state              = TCP_CLOSE;
			sk->err                = 0;
			sk->shutdown          |= SEND_SHUTDOWN;
			if (!sk->dead)
				sk->state_change(sk);
			sk->dead               = 1;
			break;

		default:
			break;
	}

	return 0;
}

/*
 * State machine for state 3, Connected State.
 * The handling of the timer(s) is in file nr_timer.c
 * Handling of state 0 and connection release is in netrom.c.
 */
static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	struct sk_buff_head temp_queue;
	struct sk_buff *skbn;
	unsigned short save_vr;
	unsigned short nr, ns;
	int queued = 0;

	nr = skb->data[18];
	ns = skb->data[17];

	switch (frametype) {

		case NR_CONNREQ:
			nr_write_internal(sk, NR_CONNACK);
			break;

		case NR_DISCREQ:
			nr_clear_queues(sk);
			nr_write_internal(sk, NR_DISCACK);
			sk->protinfo.nr->state = NR_STATE_0;
			sk->state              = TCP_CLOSE;
			sk->err                = 0;
			sk->shutdown          |= SEND_SHUTDOWN;
			if (!sk->dead)
				sk->state_change(sk);
			sk->dead               = 1;
			break;

		case NR_DISCACK:
			nr_clear_queues(sk);
			sk->protinfo.nr->state = NR_STATE_0;
			sk->state              = TCP_CLOSE;
			sk->err                = ECONNRESET;
			sk->shutdown          |= SEND_SHUTDOWN;
			if (!sk->dead)
				sk->state_change(sk);
			sk->dead               = 1;
			break;

		case NR_INFOACK:
		case NR_INFOACK | NR_CHOKE_FLAG:
		case NR_INFOACK | NR_NAK_FLAG:
		case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
			if (frametype & NR_CHOKE_FLAG) {
				sk->protinfo.nr->condition |= NR_COND_PEER_RX_BUSY;
				sk->protinfo.nr->t4timer = sk->protinfo.nr->t4;
			} else {
				sk->protinfo.nr->condition &= ~NR_COND_PEER_RX_BUSY;
				sk->protinfo.nr->t4timer = 0;
			}
			if (!nr_validate_nr(sk, nr)) {
				break;
			}
			if (frametype & NR_NAK_FLAG) {
				nr_frames_acked(sk, nr);
				nr_send_nak_frame(sk);
			} else {
				if (sk->protinfo.nr->condition & NR_COND_PEER_RX_BUSY) {
					nr_frames_acked(sk, nr);
				} else {
					nr_check_iframes_acked(sk, nr);
				}
			}
			break;

		case NR_INFO:
		case NR_INFO | NR_NAK_FLAG:
		case NR_INFO | NR_CHOKE_FLAG:
		case NR_INFO | NR_MORE_FLAG:
		case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
		case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
		case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
		case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
			if (frametype & NR_CHOKE_FLAG) {
				sk->protinfo.nr->condition |= NR_COND_PEER_RX_BUSY;
				sk->protinfo.nr->t4timer = sk->protinfo.nr->t4;
			} else {
				sk->protinfo.nr->condition &= ~NR_COND_PEER_RX_BUSY;
				sk->protinfo.nr->t4timer = 0;
			}
			if (nr_validate_nr(sk, nr)) {
				if (frametype & NR_NAK_FLAG) {
					nr_frames_acked(sk, nr);
					nr_send_nak_frame(sk);
				} else {
					if (sk->protinfo.nr->condition & NR_COND_PEER_RX_BUSY) {
						nr_frames_acked(sk, nr);
					} else {
						nr_check_iframes_acked(sk, nr);
					}
				}
			}
			queued = 1;
			skb_queue_head(&sk->protinfo.nr->reseq_queue, skb);
			if (sk->protinfo.nr->condition & NR_COND_OWN_RX_BUSY)
				break;
			skb_queue_head_init(&temp_queue);
			do {
				save_vr = sk->protinfo.nr->vr;
				while ((skbn = skb_dequeue(&sk->protinfo.nr->reseq_queue)) != NULL) {
					ns = skbn->data[17];
					if (ns == sk->protinfo.nr->vr) {
						if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
							sk->protinfo.nr->vr = (sk->protinfo.nr->vr + 1) % NR_MODULUS;
						} else {
							sk->protinfo.nr->condition |= NR_COND_OWN_RX_BUSY;
							skb_queue_tail(&temp_queue, skbn);
						}
					} else if (nr_in_rx_window(sk, ns)) {
						skb_queue_tail(&temp_queue, skbn);
					} else {
						kfree_skb(skbn, FREE_READ);
					}
				}
				while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
					skb_queue_tail(&sk->protinfo.nr->reseq_queue, skbn);
				}
			} while (save_vr != sk->protinfo.nr->vr);
			/*
			 * Window is full, ack it immediately.
			 */
			if (((sk->protinfo.nr->vl + sk->protinfo.nr->window) % NR_MODULUS) == sk->protinfo.nr->vr) {
				nr_enquiry_response(sk);
			} else {
				if (!(sk->protinfo.nr->condition & NR_COND_ACK_PENDING)) {
					sk->protinfo.nr->t2timer = sk->protinfo.nr->t2;
					sk->protinfo.nr->condition |= NR_COND_ACK_PENDING;
				}
			}
			break;

		default:
			break;
	}

	return queued;
}

/* Higher level upcall for a LAPB frame */
int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
{
	int queued = 0, frametype;

	if (sk->protinfo.nr->state == NR_STATE_0)
		return 0;

	del_timer(&sk->timer);

	frametype = skb->data[19];

	switch (sk->protinfo.nr->state) {
		case NR_STATE_1:
			queued = nr_state1_machine(sk, skb, frametype);
			break;
		case NR_STATE_2:
			queued = nr_state2_machine(sk, skb, frametype);
			break;
		case NR_STATE_3:
			queued = nr_state3_machine(sk, skb, frametype);
			break;
	}

	nr_set_timer(sk);

	return queued;
}

#endif