LXR linux/net/rose/rose

   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 <asm/system.h>
  25#include <linux/fcntl.h>
  26#include <linux/mm.h>
  27#include <linux/interrupt.h>
  28#include <net/rose.h>
  29
  30/*
  31 *      This procedure is passed a buffer descriptor for an iframe. It builds
  32 *      the rest of the control part of the frame and then writes it out.
  33 */
  34static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
  35{
  36        struct rose_sock *rose = rose_sk(sk);
  37
  38        if (skb == NULL)
  39                return;
  40
  41        skb->data[2] |= (rose->vr << 5) & 0xE0;
  42        skb->data[2] |= (rose->vs << 1) & 0x0E;
  43
  44        rose_start_idletimer(sk);
  45
  46        rose_transmit_link(skb, rose->neighbour);
  47}
  48
  49void rose_kick(struct sock *sk)
  50{
  51        struct rose_sock *rose = rose_sk(sk);
  52        struct sk_buff *skb, *skbn;
  53        unsigned short start, end;
  54
  55        if (rose->state != ROSE_STATE_3)
  56                return;
  57
  58        if (rose->condition & ROSE_COND_PEER_RX_BUSY)
  59                return;
  60
  61        if (!skb_peek(&sk->sk_write_queue))
  62                return;
  63
  64        start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
  65        end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
  66
  67        if (start == end)
  68                return;
  69
  70        rose->vs = start;
  71
  72        /*
  73         * Transmit data until either we're out of data to send or
  74         * the window is full.
  75         */
  76
  77        skb  = skb_dequeue(&sk->sk_write_queue);
  78
  79        do {
  80                if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  81                        skb_queue_head(&sk->sk_write_queue, skb);
  82                        break;
  83                }
  84
  85                skb_set_owner_w(skbn, sk);
  86
  87                /*
  88                 * Transmit the frame copy.
  89                 */
  90                rose_send_iframe(sk, skbn);
  91
  92                rose->vs = (rose->vs + 1) % ROSE_MODULUS;
  93
  94                /*
  95                 * Requeue the original data frame.
  96                 */
  97                skb_queue_tail(&rose->ack_queue, skb);
  98
  99        } while (rose->vs != end &&
 100                 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
 101
 102        rose->vl         = rose->vr;
 103        rose->condition &= ~ROSE_COND_ACK_PENDING;
 104
 105        rose_stop_timer(sk);
 106}
 107
 108/*
 109 * The following routines are taken from page 170 of the 7th ARRL Computer
 110 * Networking Conference paper, as is the whole state machine.
 111 */
 112
 113void rose_enquiry_response(struct sock *sk)
 114{
 115        struct rose_sock *rose = rose_sk(sk);
 116
 117        if (rose->condition & ROSE_COND_OWN_RX_BUSY)
 118                rose_write_internal(sk, ROSE_RNR);
 119        else
 120                rose_write_internal(sk, ROSE_RR);
 121
 122        rose->vl         = rose->vr;
 123        rose->condition &= ~ROSE_COND_ACK_PENDING;
 124
 125        rose_stop_timer(sk);
 126}
 127