net/ax25/ax25_std_subr.c

   1 /*
   2  *      AX.25 release 037
   3  *
   4  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      Most of this code is based on the SDL diagrams published in the 7th
  13  *      ARRL Computer Networking Conference papers. The diagrams have mistakes
  14  *      in them, but are mostly correct. Before you modify the code could you
  15  *      read the SDL diagrams as the code is not obvious and probably very
  16  *      easy to break;
  17  *
  18  *      History
  19  *      AX.25 036       Jonathan(G4KLX) Split from ax25_out.c.
  20  *      AX.25 037       Jonathan(G4KLX) New timer architecture.
  21  */
  22
  23 #include <linux/config.h>
  24 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
  25 #include <linux/errno.h>
  26 #include <linux/types.h>
  27 #include <linux/socket.h>
  28 #include <linux/in.h>
  29 #include <linux/kernel.h>
  30 #include <linux/sched.h>
  31 #include <linux/timer.h>
  32 #include <linux/string.h>
  33 #include <linux/sockios.h>
  34 #include <linux/net.h>
  35 #include <net/ax25.h>
  36 #include <linux/inet.h>
  37 #include <linux/netdevice.h>
  38 #include <linux/skbuff.h>
  39 #include <net/sock.h>
  40 #include <asm/uaccess.h>
  41 #include <asm/system.h>
  42 #include <linux/fcntl.h>
  43 #include <linux/mm.h>
  44 #include <linux/interrupt.h>
  45
  46 /*
  47  * The following routines are taken from page 170 of the 7th ARRL Computer
  48  * Networking Conference paper, as is the whole state machine.
  49  */
  50
  51 void ax25_std_nr_error_recovery(ax25_cb *ax25)
  52 {
  53         ax25_std_establish_data_link(ax25);
  54 }
  55
  56 void ax25_std_establish_data_link(ax25_cb *ax25)
  57 {
  58         ax25->condition = 0x00;
  59         ax25->n2count   = 0;
  60
  61         if (ax25->modulus == AX25_MODULUS)
  62                 ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
  63         else
  64                 ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND);
  65
  66         ax25_calculate_t1(ax25);
  67         ax25_stop_idletimer(ax25);
  68         ax25_stop_t3timer(ax25);
  69         ax25_stop_t2timer(ax25);
  70         ax25_start_t1timer(ax25);
  71 }
  72
  73 void ax25_std_transmit_enquiry(ax25_cb *ax25)
  74 {
  75         if (ax25->condition & AX25_COND_OWN_RX_BUSY)
  76                 ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_COMMAND);
  77         else
  78                 ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_COMMAND);
  79
  80         ax25->condition &= ~AX25_COND_ACK_PENDING;
  81
  82         ax25_calculate_t1(ax25);
  83         ax25_start_t1timer(ax25);
  84 }
  85
  86 void ax25_std_enquiry_response(ax25_cb *ax25)
  87 {
  88         if (ax25->condition & AX25_COND_OWN_RX_BUSY)
  89                 ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_RESPONSE);
  90         else
  91                 ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_RESPONSE);
  92
  93         ax25->condition &= ~AX25_COND_ACK_PENDING;
  94 }
  95
  96 void ax25_std_timeout_response(ax25_cb *ax25)
  97 {
  98         if (ax25->condition & AX25_COND_OWN_RX_BUSY)
  99                 ax25_send_control(ax25, AX25_RNR, AX25_POLLOFF, AX25_RESPONSE);
 100         else
 101                 ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE);
 102
 103         ax25->condition &= ~AX25_COND_ACK_PENDING;
 104 }
 105
 106 #endif