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 <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
  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
  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
 110 void 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  */
 127 static 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  */
 157 static 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
 173 static 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
 185 void 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
 197 void ax25_dama_on(ax25_cb *ax25)
 198 {
 199         ax25_dev_dama_on(ax25->ax25_dev);
 200         ax25->condition |= AX25_COND_DAMA_MODE;
 201 }
 202
 203 void ax25_dama_off(ax25_cb *ax25)
 204 {
 205         ax25->condition &= ~AX25_COND_DAMA_MODE;
 206         ax25_dev_dama_off(ax25->ax25_dev);
 207 }
 208