1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
9 */
10#include <linux/errno.h>
11#include <linux/types.h>
12#include <linux/socket.h>
13#include <linux/in.h>
14#include <linux/kernel.h>
15#include <linux/timer.h>
16#include <linux/string.h>
17#include <linux/sockios.h>
18#include <linux/spinlock.h>
19#include <linux/net.h>
20#include <linux/gfp.h>
21#include <net/ax25.h>
22#include <linux/inet.h>
23#include <linux/netdevice.h>
24#include <linux/skbuff.h>
25#include <net/sock.h>
26#include <asm/uaccess.h>
27#include <linux/fcntl.h>
28#include <linux/mm.h>
29#include <linux/interrupt.h>
30
31void ax25_ds_nr_error_recovery(ax25_cb *ax25)
32{
33	ax25_ds_establish_data_link(ax25);
34}
35
36/*
37 *	dl1bke 960114: transmit I frames on DAMA poll
38 */
39void ax25_ds_enquiry_response(ax25_cb *ax25)
40{
41	ax25_cb *ax25o;
42
43	/* Please note that neither DK4EG's nor DG2FEF's
44	 * DAMA spec mention the following behaviour as seen
45	 * with TheFirmware:
46	 *
47	 * 	DB0ACH->DL1BKE <RR C P R0> [DAMA]
48	 *	DL1BKE->DB0ACH <I NR=0 NS=0>
49	 *	DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
50	 *	DL1BKE->DB0ACH <RR R F R0>
51	 *
52	 * The Flexnet DAMA Master implementation apparently
53	 * insists on the "proper" AX.25 behaviour:
54	 *
55	 * 	DB0ACH->DL1BKE <RR C P R0> [DAMA]
56	 *	DL1BKE->DB0ACH <RR R F R0>
57	 *	DL1BKE->DB0ACH <I NR=0 NS=0>
58	 *	DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
59	 *
60	 * Flexnet refuses to send us *any* I frame if we send
61	 * a REJ in case AX25_COND_REJECT is set. It is superfluous in
62	 * this mode anyway (a RR or RNR invokes the retransmission).
63	 * Is this a Flexnet bug?
64	 */
65
66	ax25_std_enquiry_response(ax25);
67
68	if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) {
69		ax25_requeue_frames(ax25);
70		ax25_kick(ax25);
71	}
72
73	if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL)
74		ax25_ds_t1_timeout(ax25);
75	else
76		ax25->n2count = 0;
77
78	ax25_start_t3timer(ax25);
79	ax25_ds_set_timer(ax25->ax25_dev);
80
81	spin_lock(&ax25_list_lock);
82	ax25_for_each(ax25o, &ax25_list) {
83		if (ax25o == ax25)
84			continue;
85
86		if (ax25o->ax25_dev != ax25->ax25_dev)
87			continue;
88
89		if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) {
90			ax25_ds_t1_timeout(ax25o);
91			continue;
92		}
93
94		if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) {
95			ax25_requeue_frames(ax25o);
96			ax25_kick(ax25o);
97		}
98
99		if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL)
100			ax25_ds_t1_timeout(ax25o);
101
102		/* do not start T3 for listening sockets (tnx DD8NE) */
103
104		if (ax25o->state != AX25_STATE_0)
105			ax25_start_t3timer(ax25o);
106	}
107	spin_unlock(&ax25_list_lock);
108}
109
110void ax25_ds_establish_data_link(ax25_cb *ax25)
111{
112	ax25->condition &= AX25_COND_DAMA_MODE;
113	ax25->n2count    = 0;
114	ax25_calculate_t1(ax25);
115	ax25_start_t1timer(ax25);
116	ax25_stop_t2timer(ax25);
117	ax25_start_t3timer(ax25);
118}
119
120/*
121 *	:::FIXME:::
122 *	This is a kludge. Not all drivers recognize kiss commands.
123 *	We need a driver level  request to switch duplex mode, that does
124 *	either SCC changing, PI config or KISS as required. Currently
125 *	this request isn't reliable.
126 */
127static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param)
128{
129	struct sk_buff *skb;
130	unsigned char *p;
131
132	if (ax25_dev->dev == NULL)
133		return;
134
135	if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL)
136		return;
137
138	skb_reset_network_header(skb);
139	p = skb_put(skb, 2);
140
141	*p++ = cmd;
142	*p++ = param;
143
144	skb->protocol = ax25_type_trans(skb, ax25_dev->dev);
145
146	dev_queue_xmit(skb);
147}
148
149/*
150 *	A nasty problem arises if we count the number of DAMA connections
151 *	wrong, especially when connections on the device already existed
152 *	and our network node (or the sysop) decides to turn on DAMA Master
153 *	mode. We thus flag the 'real' slave connections with
154 *	ax25->dama_slave=1 and look on every disconnect if still slave
155 *	connections exist.
156 */
157static int ax25_check_dama_slave(ax25_dev *ax25_dev)
158{
159	ax25_cb *ax25;
160	int res = 0;
161
162	spin_lock(&ax25_list_lock);
163	ax25_for_each(ax25, &ax25_list)
164		if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) {
165			res = 1;
166			break;
167		}
168	spin_unlock(&ax25_list_lock);
169
170	return res;
171}
172
173static void ax25_dev_dama_on(ax25_dev *ax25_dev)
174{
175	if (ax25_dev == NULL)
176		return;
177
178	if (ax25_dev->dama.slave == 0)
179		ax25_kiss_cmd(ax25_dev, 5, 1);
180
181	ax25_dev->dama.slave = 1;
182	ax25_ds_set_timer(ax25_dev);
183}
184
185void ax25_dev_dama_off(ax25_dev *ax25_dev)
186{
187	if (ax25_dev == NULL)
188		return;
189
190	if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) {
191		ax25_kiss_cmd(ax25_dev, 5, 0);
192		ax25_dev->dama.slave = 0;
193		ax25_ds_del_timer(ax25_dev);
194	}
195}
196
197void ax25_dama_on(ax25_cb *ax25)
198{
199	ax25_dev_dama_on(ax25->ax25_dev);
200	ax25->condition |= AX25_COND_DAMA_MODE;
201}
202
203void ax25_dama_off(ax25_cb *ax25)
204{
205	ax25->condition &= ~AX25_COND_DAMA_MODE;
206	ax25_dev_dama_off(ax25->ax25_dev);
207}
208
209