LXR linux/net/rose/rose

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *
   4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   5 */
   6#include <linux/errno.h>
   7#include <linux/types.h>
   8#include <linux/socket.h>
   9#include <linux/in.h>
  10#include <linux/kernel.h>
  11#include <linux/timer.h>
  12#include <linux/string.h>
  13#include <linux/sockios.h>
  14#include <linux/net.h>
  15#include <linux/gfp.h>
  16#include <net/ax25.h>
  17#include <linux/inet.h>
  18#include <linux/netdevice.h>
  19#include <linux/skbuff.h>
  20#include <net/sock.h>
  21#include <linux/fcntl.h>
  22#include <linux/mm.h>
  23#include <linux/interrupt.h>
  24#include <net/rose.h>
  25
  26/*
  27 *      This procedure is passed a buffer descriptor for an iframe. It builds
  28 *      the rest of the control part of the frame and then writes it out.
  29 */
  30static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
  31{
  32        struct rose_sock *rose = rose_sk(sk);
  33
  34        if (skb == NULL)
  35                return;
  36
  37        skb->data[2] |= (rose->vr << 5) & 0xE0;
  38        skb->data[2] |= (rose->vs << 1) & 0x0E;
  39
  40        rose_start_idletimer(sk);
  41
  42        rose_transmit_link(skb, rose->neighbour);
  43}
  44
  45void rose_kick(struct sock *sk)
  46{
  47        struct rose_sock *rose = rose_sk(sk);
  48        struct sk_buff *skb, *skbn;
  49        unsigned short start, end;
  50
  51        if (rose->state != ROSE_STATE_3)
  52                return;
  53
  54        if (rose->condition & ROSE_COND_PEER_RX_BUSY)
  55                return;
  56
  57        if (!skb_peek(&sk->sk_write_queue))
  58                return;
  59
  60        start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
  61        end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
  62
  63        if (start == end)
  64                return;
  65
  66        rose->vs = start;
  67
  68        /*
  69         * Transmit data until either we're out of data to send or
  70         * the window is full.
  71         */
  72
  73        skb  = skb_dequeue(&sk->sk_write_queue);
  74
  75        do {
  76                if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  77                        skb_queue_head(&sk->sk_write_queue, skb);
  78                        break;
  79                }
  80
  81                skb_set_owner_w(skbn, sk);
  82
  83                /*
  84                 * Transmit the frame copy.
  85                 */
  86                rose_send_iframe(sk, skbn);
  87
  88                rose->vs = (rose->vs + 1) % ROSE_MODULUS;
  89
  90                /*
  91                 * Requeue the original data frame.
  92                 */
  93                skb_queue_tail(&rose->ack_queue, skb);
  94
  95        } while (rose->vs != end &&
  96                 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
  97
  98        rose->vl         = rose->vr;
  99        rose->condition &= ~ROSE_COND_ACK_PENDING;
 100
 101        rose_stop_timer(sk);
 102}
 103
 104/*
 105 * The following routines are taken from page 170 of the 7th ARRL Computer
 106 * Networking Conference paper, as is the whole state machine.
 107 */
 108
 109void rose_enquiry_response(struct sock *sk)
 110{
 111        struct rose_sock *rose = rose_sk(sk);
 112
 113        if (rose->condition & ROSE_COND_OWN_RX_BUSY)
 114                rose_write_internal(sk, ROSE_RNR);
 115        else
 116                rose_write_internal(sk, ROSE_RR);
 117
 118        rose->vl         = rose->vr;
 119        rose->condition &= ~ROSE_COND_ACK_PENDING;
 120
 121        rose_stop_timer(sk);
 122}
 123