net/rose/rose_out.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  */
   9 #include <linux/errno.h>
  10 #include <linux/types.h>
  11 #include <linux/socket.h>
  12 #include <linux/in.h>
  13 #include <linux/kernel.h>
  14 #include <linux/timer.h>
  15 #include <linux/string.h>
  16 #include <linux/sockios.h>
  17 #include <linux/net.h>
  18 #include <linux/gfp.h>
  19 #include <net/ax25.h>
  20 #include <linux/inet.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <net/sock.h>
  24 #include <linux/fcntl.h>
  25 #include <linux/mm.h>
  26 #include <linux/interrupt.h>
  27 #include <net/rose.h>
  28
  29 /*
  30  *      This procedure is passed a buffer descriptor for an iframe. It builds
  31  *      the rest of the control part of the frame and then writes it out.
  32  */
  33 static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
  34 {
  35         struct rose_sock *rose = rose_sk(sk);
  36
  37         if (skb == NULL)
  38                 return;
  39
  40         skb->data[2] |= (rose->vr << 5) & 0xE0;
  41         skb->data[2] |= (rose->vs << 1) & 0x0E;
  42
  43         rose_start_idletimer(sk);
  44
  45         rose_transmit_link(skb, rose->neighbour);
  46 }
  47
  48 void rose_kick(struct sock *sk)
  49 {
  50         struct rose_sock *rose = rose_sk(sk);
  51         struct sk_buff *skb, *skbn;
  52         unsigned short start, end;
  53
  54         if (rose->state != ROSE_STATE_3)
  55                 return;
  56
  57         if (rose->condition & ROSE_COND_PEER_RX_BUSY)
  58                 return;
  59
  60         if (!skb_peek(&sk->sk_write_queue))
  61                 return;
  62
  63         start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
  64         end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
  65
  66         if (start == end)
  67                 return;
  68
  69         rose->vs = start;
  70
  71         /*
  72          * Transmit data until either we're out of data to send or
  73          * the window is full.
  74          */
  75
  76         skb  = skb_dequeue(&sk->sk_write_queue);
  77
  78         do {
  79                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  80                         skb_queue_head(&sk->sk_write_queue, skb);
  81                         break;
  82                 }
  83
  84                 skb_set_owner_w(skbn, sk);
  85
  86                 /*
  87                  * Transmit the frame copy.
  88                  */
  89                 rose_send_iframe(sk, skbn);
  90
  91                 rose->vs = (rose->vs + 1) % ROSE_MODULUS;
  92
  93                 /*
  94                  * Requeue the original data frame.
  95                  */
  96                 skb_queue_tail(&rose->ack_queue, skb);
  97
  98         } while (rose->vs != end &&
  99                  (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
 100
 101         rose->vl         = rose->vr;
 102         rose->condition &= ~ROSE_COND_ACK_PENDING;
 103
 104         rose_stop_timer(sk);
 105 }
 106
 107 /*
 108  * The following routines are taken from page 170 of the 7th ARRL Computer
 109  * Networking Conference paper, as is the whole state machine.
 110  */
 111
 112 void rose_enquiry_response(struct sock *sk)
 113 {
 114         struct rose_sock *rose = rose_sk(sk);
 115
 116         if (rose->condition & ROSE_COND_OWN_RX_BUSY)
 117                 rose_write_internal(sk, ROSE_RNR);
 118         else
 119                 rose_write_internal(sk, ROSE_RR);
 120
 121         rose->vl         = rose->vr;
 122         rose->condition &= ~ROSE_COND_ACK_PENDING;
 123
 124         rose_stop_timer(sk);
 125 }