net/rose/rose_out.c

   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  */
  30 static 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
  45 void 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
 109 void 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 }