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 <asm/system.h>
  28 #include <linux/fcntl.h>
  29 #include <linux/mm.h>
  30 #include <linux/interrupt.h>
  31
  32 void ax25_ds_nr_error_recovery(ax25_cb *ax25)
  33 {
  34         ax25_ds_establish_data_link(ax25);
  35 }
  36
  37 /*
  38  *      dl1bke 960114: transmit I frames on DAMA poll
  39  */
  40 void ax25_ds_enquiry_response(ax25_cb *ax25)
  41 {
  42         ax25_cb *ax25o;
  43         struct hlist_node *node;
  44
  45         /* Please note that neither DK4EG's nor DG2FEF's
  46          * DAMA spec mention the following behaviour as seen
  47          * with TheFirmware:
  48          *
  49          *      DB0ACH->DL1BKE <RR C P R0> [DAMA]
  50          *      DL1BKE->DB0ACH <I NR=0 NS=0>
  51          *      DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
  52          *      DL1BKE->DB0ACH <RR R F R0>
  53          *
  54          * The Flexnet DAMA Master implementation apparently
  55          * insists on the "proper" AX.25 behaviour:
  56          *
  57          *      DB0ACH->DL1BKE <RR C P R0> [DAMA]
  58          *      DL1BKE->DB0ACH <RR R F R0>
  59          *      DL1BKE->DB0ACH <I NR=0 NS=0>
  60          *      DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5>
  61          *
  62          * Flexnet refuses to send us *any* I frame if we send
  63          * a REJ in case AX25_COND_REJECT is set. It is superfluous in
  64          * this mode anyway (a RR or RNR invokes the retransmission).
  65          * Is this a Flexnet bug?
  66          */
  67
  68         ax25_std_enquiry_response(ax25);
  69
  70         if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) {
  71                 ax25_requeue_frames(ax25);
  72                 ax25_kick(ax25);
  73         }
  74
  75         if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL)
  76                 ax25_ds_t1_timeout(ax25);
  77         else
  78                 ax25->n2count = 0;
  79
  80         ax25_start_t3timer(ax25);
  81         ax25_ds_set_timer(ax25->ax25_dev);
  82
  83         spin_lock(&ax25_list_lock);
  84         ax25_for_each(ax25o, node, &ax25_list) {
  85                 if (ax25o == ax25)
  86                         continue;
  87
  88                 if (ax25o->ax25_dev != ax25->ax25_dev)
  89                         continue;
  90
  91                 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) {
  92                         ax25_ds_t1_timeout(ax25o);
  93                         continue;
  94                 }
  95
  96                 if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) {
  97                         ax25_requeue_frames(ax25o);
  98                         ax25_kick(ax25o);
  99                 }
 100
 101                 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL)
 102                         ax25_ds_t1_timeout(ax25o);
 103
 104                 /* do not start T3 for listening sockets (tnx DD8NE) */
 105
 106                 if (ax25o->state != AX25_STATE_0)
 107                         ax25_start_t3timer(ax25o);
 108         }
 109         spin_unlock(&ax25_list_lock);
 110 }
 111
 112 void ax25_ds_establish_data_link(ax25_cb *ax25)
 113 {
 114         ax25->condition &= AX25_COND_DAMA_MODE;
 115         ax25->n2count    = 0;
 116         ax25_calculate_t1(ax25);
 117         ax25_start_t1timer(ax25);
 118         ax25_stop_t2timer(ax25);
 119         ax25_start_t3timer(ax25);
 120 }
 121
 122 /*
 123  *      :::FIXME:::
 124  *      This is a kludge. Not all drivers recognize kiss commands.
 125  *      We need a driver level  request to switch duplex mode, that does
 126  *      either SCC changing, PI config or KISS as required. Currently
 127  *      this request isn't reliable.
 128  */
 129 static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param)
 130 {
 131         struct sk_buff *skb;
 132         unsigned char *p;
 133
 134         if (ax25_dev->dev == NULL)
 135                 return;
 136
 137         if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL)
 138                 return;
 139
 140         skb_reset_network_header(skb);
 141         p = skb_put(skb, 2);
 142
 143         *p++ = cmd;
 144         *p++ = param;
 145
 146         skb->protocol = ax25_type_trans(skb, ax25_dev->dev);
 147
 148         dev_queue_xmit(skb);
 149 }
 150
 151 /*
 152  *      A nasty problem arises if we count the number of DAMA connections
 153  *      wrong, especially when connections on the device already existed
 154  *      and our network node (or the sysop) decides to turn on DAMA Master
 155  *      mode. We thus flag the 'real' slave connections with
 156  *      ax25->dama_slave=1 and look on every disconnect if still slave
 157  *      connections exist.
 158  */
 159 static int ax25_check_dama_slave(ax25_dev *ax25_dev)
 160 {
 161         ax25_cb *ax25;
 162         int res = 0;
 163         struct hlist_node *node;
 164
 165         spin_lock(&ax25_list_lock);
 166         ax25_for_each(ax25, node, &ax25_list)
 167                 if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) {
 168                         res = 1;
 169                         break;
 170                 }
 171         spin_unlock(&ax25_list_lock);
 172
 173         return res;
 174 }
 175
 176 static void ax25_dev_dama_on(ax25_dev *ax25_dev)
 177 {
 178         if (ax25_dev == NULL)
 179                 return;
 180
 181         if (ax25_dev->dama.slave == 0)
 182                 ax25_kiss_cmd(ax25_dev, 5, 1);
 183
 184         ax25_dev->dama.slave = 1;
 185         ax25_ds_set_timer(ax25_dev);
 186 }
 187
 188 void ax25_dev_dama_off(ax25_dev *ax25_dev)
 189 {
 190         if (ax25_dev == NULL)
 191                 return;
 192
 193         if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) {
 194                 ax25_kiss_cmd(ax25_dev, 5, 0);
 195                 ax25_dev->dama.slave = 0;
 196                 ax25_ds_del_timer(ax25_dev);
 197         }
 198 }
 199
 200 void ax25_dama_on(ax25_cb *ax25)
 201 {
 202         ax25_dev_dama_on(ax25->ax25_dev);
 203         ax25->condition |= AX25_COND_DAMA_MODE;
 204 }
 205
 206 void ax25_dama_off(ax25_cb *ax25)
 207 {
 208         ax25->condition &= ~AX25_COND_DAMA_MODE;
 209         ax25_dev_dama_off(ax25->ax25_dev);
 210 }
 211