aboutsummaryrefslogtreecommitdiffstats
path: root/net/ax25/ax25_ds_subr.c
blob: 4d22d4430ec8a85128484685c4886ca4adc73cfa (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
/*
 * This program 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.
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
 */
#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/spinlock.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 <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>

void ax25_ds_nr_error_recovery(ax25_cb *ax25)
{
	ax25_ds_establish_data_link(ax25);
}

/*
 *	dl1bke 960114: transmit I frames on DAMA poll
 */
void ax25_ds_enquiry_response(ax25_cb *ax25)
{
	ax25_cb *ax25o;
	struct hlist_node *node;

	/* Please note that neither DK4EG´s nor DG2FEF´s
	 * DAMA spec mention the following behaviour as seen
	 * with TheFirmware:
	 *
	 * 	DB0ACH->DL1BKE <RR C P R0> [DAMA]
	 *	DL1BKE->DB0ACH <I NR=0 NS=0>
	 *	DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
	 *	DL1BKE->DB0ACH <RR R F R0>
	 *
	 * The Flexnet DAMA Master implementation apparently
	 * insists on the "proper" AX.25 behaviour:
	 *
	 * 	DB0ACH->DL1BKE <RR C P R0> [DAMA]
	 *	DL1BKE->DB0ACH <RR R F R0>
	 *	DL1BKE->DB0ACH <I NR=0 NS=0>
	 *	DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
	 *
	 * Flexnet refuses to send us *any* I frame if we send
	 * a REJ in case AX25_COND_REJECT is set. It is superfluous in
	 * this mode anyway (a RR or RNR invokes the retransmission).
	 * Is this a Flexnet bug?
	 */

	ax25_std_enquiry_response(ax25);

	if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) {
		ax25_requeue_frames(ax25);
		ax25_kick(ax25);
	}

	if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL)
		ax25_ds_t1_timeout(ax25);
	else
		ax25->n2count = 0;

	ax25_start_t3timer(ax25);
	ax25_ds_set_timer(ax25->ax25_dev);

	spin_lock(&ax25_list_lock);
	ax25_for_each(ax25o, node, &ax25_list) {
		if (ax25o == ax25)
			continue;

		if (ax25o->ax25_dev != ax25->ax25_dev)
			continue;

		if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) {
			ax25_ds_t1_timeout(ax25o);
			continue;
		}

		if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) {
			ax25_requeue_frames(ax25o);
			ax25_kick(ax25o);
		}

		if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL)
			ax25_ds_t1_timeout(ax25o);

		/* do not start T3 for listening sockets (tnx DD8NE) */

		if (ax25o->state != AX25_STATE_0)
			ax25_start_t3timer(ax25o);
	}
	spin_unlock(&ax25_list_lock);
}

void ax25_ds_establish_data_link(ax25_cb *ax25)
{
	ax25->condition &= AX25_COND_DAMA_MODE;
	ax25->n2count    = 0;
	ax25_calculate_t1(ax25);
	ax25_start_t1timer(ax25);
	ax25_stop_t2timer(ax25);
	ax25_start_t3timer(ax25);
}

/*
 *	:::FIXME:::
 *	This is a kludge. Not all drivers recognize kiss commands.
 *	We need a driver level  request to switch duplex mode, that does
 *	either SCC changing, PI config or KISS as required. Currently
 *	this request isn't reliable.
 */
static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param)
{
	struct sk_buff *skb;
	unsigned char *p;

	if (ax25_dev->dev == NULL)
		return;

	if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL)
		return;

	skb->nh.raw = skb->data;
	p = skb_put(skb, 2);

	*p++ = cmd;
	*p++ = param;

	skb->protocol = ax25_type_trans(skb, ax25_dev->dev);

	dev_queue_xmit(skb);
}

/*
 *	A nasty problem arises if we count the number of DAMA connections
 *	wrong, especially when connections on the device already existed
 *	and our network node (or the sysop) decides to turn on DAMA Master
 *	mode. We thus flag the 'real' slave connections with
 *	ax25->dama_slave=1 and look on every disconnect if still slave
 *	connections exist.
 */
static int ax25_check_dama_slave(ax25_dev *ax25_dev)
{
	ax25_cb *ax25;
	int res = 0;
	struct hlist_node *node;

	spin_lock(&ax25_list_lock);
	ax25_for_each(ax25, node, &ax25_list)
		if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) {
			res = 1;
			break;
		}
	spin_unlock(&ax25_list_lock);

	return res;
}

static void ax25_dev_dama_on(ax25_dev *ax25_dev)
{
	if (ax25_dev == NULL)
		return;

	if (ax25_dev->dama.slave == 0)
		ax25_kiss_cmd(ax25_dev, 5, 1);

	ax25_dev->dama.slave = 1;
	ax25_ds_set_timer(ax25_dev);
}

void ax25_dev_dama_off(ax25_dev *ax25_dev)
{
	if (ax25_dev == NULL)
		return;

	if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) {
		ax25_kiss_cmd(ax25_dev, 5, 0);
		ax25_dev->dama.slave = 0;
		ax25_ds_del_timer(ax25_dev);
	}
}

void ax25_dama_on(ax25_cb *ax25)
{
	ax25_dev_dama_on(ax25->ax25_dev);
	ax25->condition |= AX25_COND_DAMA_MODE;
}

void ax25_dama_off(ax25_cb *ax25)
{
	ax25->condition &= ~AX25_COND_DAMA_MODE;
	ax25_dev_dama_off(ax25->ax25_dev);
}