127 строки
2.8 KiB
C
127 строки
2.8 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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*/
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <asm/system.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <net/rose.h>
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/*
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* This procedure is passed a buffer descriptor for an iframe. It builds
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* the rest of the control part of the frame and then writes it out.
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*/
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static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
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{
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struct rose_sock *rose = rose_sk(sk);
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if (skb == NULL)
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return;
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skb->data[2] |= (rose->vr << 5) & 0xE0;
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skb->data[2] |= (rose->vs << 1) & 0x0E;
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rose_start_idletimer(sk);
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rose_transmit_link(skb, rose->neighbour);
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}
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void rose_kick(struct sock *sk)
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{
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struct rose_sock *rose = rose_sk(sk);
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struct sk_buff *skb, *skbn;
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unsigned short start, end;
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if (rose->state != ROSE_STATE_3)
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return;
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if (rose->condition & ROSE_COND_PEER_RX_BUSY)
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return;
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if (!skb_peek(&sk->sk_write_queue))
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return;
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start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
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end = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
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if (start == end)
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return;
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rose->vs = start;
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/*
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* Transmit data until either we're out of data to send or
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* the window is full.
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*/
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skb = skb_dequeue(&sk->sk_write_queue);
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do {
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if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
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skb_queue_head(&sk->sk_write_queue, skb);
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break;
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}
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skb_set_owner_w(skbn, sk);
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/*
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* Transmit the frame copy.
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*/
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rose_send_iframe(sk, skbn);
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rose->vs = (rose->vs + 1) % ROSE_MODULUS;
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/*
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* Requeue the original data frame.
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*/
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skb_queue_tail(&rose->ack_queue, skb);
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} while (rose->vs != end &&
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(skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
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rose->vl = rose->vr;
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rose->condition &= ~ROSE_COND_ACK_PENDING;
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rose_stop_timer(sk);
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}
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/*
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* The following routines are taken from page 170 of the 7th ARRL Computer
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* Networking Conference paper, as is the whole state machine.
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*/
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void rose_enquiry_response(struct sock *sk)
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{
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struct rose_sock *rose = rose_sk(sk);
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if (rose->condition & ROSE_COND_OWN_RX_BUSY)
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rose_write_internal(sk, ROSE_RNR);
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else
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rose_write_internal(sk, ROSE_RR);
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rose->vl = rose->vr;
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rose->condition &= ~ROSE_COND_ACK_PENDING;
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rose_stop_timer(sk);
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}
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