Linux Kernel  3.7.1
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ax25_ds_subr.c
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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 ([email protected])
8  * Copyright (C) Joerg Reuter DL1BKE ([email protected])
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 
32 {
34 }
35 
36 /*
37  * dl1bke 960114: transmit I frames on DAMA poll
38  */
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 
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);
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 
112 {
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 
200 {
201  ax25_dev_dama_on(ax25->ax25_dev);
203 }
204 
206 {
207  ax25->condition &= ~AX25_COND_DAMA_MODE;
209 }
210