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 <net/ax25.h>
21 #include <linux/inet.h>
22 #include <linux/netdevice.h>
23 #include <linux/skbuff.h>
24 #include <net/sock.h>
25 #include <asm/uaccess.h>
26 #include <asm/system.h>
27 #include <linux/fcntl.h>
28 #include <linux/mm.h>
29 #include <linux/interrupt.h>
30
31 void 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 */
39 void ax25_ds_enquiry_response(ax25_cb *ax25)
40 {
41 ax25_cb *ax25o;
42 struct hlist_node *node;
43
44 /* Please note that neither DK4EG's nor DG2FEF's
45 * DAMA spec mention the following behaviour as seen
46 * with TheFirmware:
47 *
48 * DB0ACH->DL1BKE <RR C P R0> [DAMA]
49 * DL1BKE->DB0ACH <I NR=0 NS=0>
50 * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
51 * DL1BKE->DB0ACH <RR R F R0>
52 *
53 * The Flexnet DAMA Master implementation apparently
54 * insists on the "proper" AX.25 behaviour:
55 *
56 * DB0ACH->DL1BKE <RR C P R0> [DAMA]
57 * DL1BKE->DB0ACH <RR R F R0>
58 * DL1BKE->DB0ACH <I NR=0 NS=0>
59 * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
60 *
61 * Flexnet refuses to send us *any* I frame if we send
62 * a REJ in case AX25_COND_REJECT is set. It is superfluous in
63 * this mode anyway (a RR or RNR invokes the retransmission).
64 * Is this a Flexnet bug?
65 */
66
67 ax25_std_enquiry_response(ax25);
68
69 if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) {
70 ax25_requeue_frames(ax25);
71 ax25_kick(ax25);
72 }
73
74 if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL)
75 ax25_ds_t1_timeout(ax25);
76 else
77 ax25->n2count = 0;
78
79 ax25_start_t3timer(ax25);
80 ax25_ds_set_timer(ax25->ax25_dev);
81
82 spin_lock(&ax25_list_lock);
83 ax25_for_each(ax25o, node, &ax25_list) {
84 if (ax25o == ax25)
85 continue;
86
87 if (ax25o->ax25_dev != ax25->ax25_dev)
88 continue;
89
90 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) {
91 ax25_ds_t1_timeout(ax25o);
92 continue;
93 }
94
95 if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) {
96 ax25_requeue_frames(ax25o);
97 ax25_kick(ax25o);
98 }
99
100 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL)
101 ax25_ds_t1_timeout(ax25o);
102
103 /* do not start T3 for listening sockets (tnx DD8NE) */
104
105 if (ax25o->state != AX25_STATE_0)
106 ax25_start_t3timer(ax25o);
107 }
108 spin_unlock(&ax25_list_lock);
109 }
110
111 void ax25_ds_establish_data_link(ax25_cb *ax25)
112 {
113 ax25->condition &= AX25_COND_DAMA_MODE;
114 ax25->n2count = 0;
115 ax25_calculate_t1(ax25);
116 ax25_start_t1timer(ax25);
117 ax25_stop_t2timer(ax25);
118 ax25_start_t3timer(ax25);
119 }
120
121 /*
122 * :::FIXME:::
123 * This is a kludge. Not all drivers recognize kiss commands.
124 * We need a driver level request to switch duplex mode, that does
125 * either SCC changing, PI config or KISS as required. Currently
126 * this request isn't reliable.
127 */
128 static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param)
129 {
130 struct sk_buff *skb;
131 unsigned char *p;
132
133 if (ax25_dev->dev == NULL)
134 return;
135
136 if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL)
137 return;
138
139 skb_reset_network_header(skb);
140 p = skb_put(skb, 2);
141
142 *p++ = cmd;
143 *p++ = param;
144
145 skb->protocol = ax25_type_trans(skb, ax25_dev->dev);
146
147 dev_queue_xmit(skb);
148 }
149
150 /*
151 * A nasty problem arises if we count the number of DAMA connections
152 * wrong, especially when connections on the device already existed
153 * and our network node (or the sysop) decides to turn on DAMA Master
154 * mode. We thus flag the 'real' slave connections with
155 * ax25->dama_slave=1 and look on every disconnect if still slave
156 * connections exist.
157 */
158 static int ax25_check_dama_slave(ax25_dev *ax25_dev)
159 {
160 ax25_cb *ax25;
161 int res = 0;
162 struct hlist_node *node;
163
164 spin_lock(&ax25_list_lock);
165 ax25_for_each(ax25, node, &ax25_list)
166 if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) {
167 res = 1;
168 break;
169 }
170 spin_unlock(&ax25_list_lock);
171
172 return res;
173 }
174
175 static void ax25_dev_dama_on(ax25_dev *ax25_dev)
176 {
177 if (ax25_dev == NULL)
178 return;
179
180 if (ax25_dev->dama.slave == 0)
181 ax25_kiss_cmd(ax25_dev, 5, 1);
182
183 ax25_dev->dama.slave = 1;
184 ax25_ds_set_timer(ax25_dev);
185 }
186
187 void ax25_dev_dama_off(ax25_dev *ax25_dev)
188 {
189 if (ax25_dev == NULL)
190 return;
191
192 if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) {
193 ax25_kiss_cmd(ax25_dev, 5, 0);
194 ax25_dev->dama.slave = 0;
195 ax25_ds_del_timer(ax25_dev);
196 }
197 }
198
199 void ax25_dama_on(ax25_cb *ax25)
200 {
201 ax25_dev_dama_on(ax25->ax25_dev);
202 ax25->condition |= AX25_COND_DAMA_MODE;
203 }
204
205 void ax25_dama_off(ax25_cb *ax25)
206 {
207 ax25->condition &= ~AX25_COND_DAMA_MODE;
208 ax25_dev_dama_off(ax25->ax25_dev);
209 }
210
211
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