linux/net/rose/rose_out.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 */
   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 */
  33static 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
  48void 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
 112void 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}
 126
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