linux/net/ax25/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 (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
  31void 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 */
  39void 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
 111void 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 */
 128static 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 */
 158static 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
 175static 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
 187void 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
 199void ax25_dama_on(ax25_cb *ax25)
 200{
 201        ax25_dev_dama_on(ax25->ax25_dev);
 202        ax25->condition |= AX25_COND_DAMA_MODE;
 203}
 204
 205void 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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