net/ax25/ax25_ds_subr.c

   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