/*
* $Id$
*
* Copyright (C) 2003-2015 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.net.ipv4.tcp;
import java.net.SocketException;
import java.util.Iterator;
import java.util.LinkedList;
import org.apache.log4j.Logger;
import org.jnode.net.ipv4.IPv4Header;
/**
* @author Ewout Prangsma (epr@users.sourceforge.net)
*/
public class TCPOutChannel {
private static final boolean DEBUG = false;
/**
* My logger
*/
private static final Logger log = Logger.getLogger(TCPOutChannel.class);
/**
* The protocol
*/
private final TCPProtocol tcp;
/**
* All unacked segments
*/
private final LinkedList<TCPOutSegment> unackedSegments = new LinkedList<TCPOutSegment>();
/**
* The outgoing databuffer
*/
private final TCPDataBuffer dataBuffer;
/**
* Send unacknowledged
*/
private int snd_unack;
/**
* Send next seq-nr
*/
private int snd_next;
/**
* Highest seq-nr sent; used to recognize retransmits
*/
private int snd_max;
/**
* Maximum segment size (determined by the foreign part of the connection
*/
private int mss;
/**
* The control block I belong to
*/
private final TCPControlBlock controlBlock;
/**
* Number of ticks before a retransmit timeout
*/
private int timeoutTicks = 6;
/**
* Create a new instance
*/
public TCPOutChannel(TCPProtocol tcp, TCPControlBlock controlBlock, int isn) {
this.tcp = tcp;
this.controlBlock = controlBlock;
this.dataBuffer = new TCPDataBuffer(TCPConstants.TCP_BUFFER_SIZE);
this.snd_unack = isn;
this.snd_next = isn;
this.snd_max = isn;
this.mss = TCPConstants.TCP_DEFAULT_MSS;
}
/**
* Process an ack-nr.
* Remove all segments that have been acknowledged and remove
* the occupied data from the databuffer.
*
* @param ackNr
*/
public synchronized void processAck(int ackNr) {
// Is the ack valid?
if (snd_unack == ackNr) {
// Not a new ack, ignore it
return;
} else if (!TCPUtils.SEQ_LT(snd_unack, ackNr)) {
// snd_unack < ackNr violated
log.debug("snd_unack < ackNr violated");
return;
}
if (!TCPUtils.SEQ_LE(ackNr, snd_max)) {
// ackNr <= snd_max violated
log.debug("ackNr <= snd_max violated");
return;
}
// The ackNr is valid
final int diff = ackNr - snd_unack;
snd_unack = ackNr;
// Remove data from the databuffer
dataBuffer.pull(diff);
for (Iterator<TCPOutSegment> i = unackedSegments.iterator(); i.hasNext();) {
final TCPOutSegment seg = (TCPOutSegment) i.next();
final int seqNr = seg.getSeqNr();
if (TCPUtils.SEQ_LT(seqNr, ackNr)) {
// Remove the segment
i.remove();
} else {
// Adjust the dataOffset
seg.adjustDataOffset(diff);
}
}
// Notify any blocked threads
notifyAll();
}
/**
* Process timeout handling
*/
public void timeout() throws SocketException {
//allocation free looping
for (TCPOutSegment seg : unackedSegments) {
seg.timeout(tcp);
}
}
public int getBufferSize() {
return dataBuffer.getLength();
}
/**
* Send a TCP segment containing no data
*
* @param ipHdr
* @param hdr
*/
public void send(IPv4Header ipHdr, TCPHeader hdr) throws SocketException {
// Check the datalength
if (hdr.getDataLength() != 0) {
throw new IllegalArgumentException("dataLength must be 0");
}
// Do the actual send
sendHelper(ipHdr, hdr, 0);
}
/**
* Send a TCP segment containing the given data.
* This method blocks until there is enough space in the output buffer
* to hold the data.
*
* @param ipHdr
* @param hdr
* @param data
* @param offset
* @param length Must be smaller or equal to mss.
*/
public synchronized void send(IPv4Header ipHdr, TCPHeader hdr, byte[] data, int offset,
int length) throws SocketException {
if (DEBUG) {
log.debug("outChannel.send(ipHdr,hdr,data," + offset + ", " + length + ')');
}
// Check for maximum datalength
if (length > mss) {
throw new IllegalArgumentException("dataLength must be <= mss");
}
// Wait until there is space in the output buffer
while ((length > dataBuffer.getFreeSize()) && !controlBlock.isReset()) {
try {
wait();
} catch (InterruptedException ex) {
// Ignore
}
}
if (controlBlock.isReset()) {
throw new SocketException("Connection reset");
}
// Add to databuffer
final int bufOfs = dataBuffer.add(data, offset, length);
// Update tcp header
hdr.setDataLength(length);
// Do the actual send
sendHelper(ipHdr, hdr, bufOfs);
}
/**
* Do the actual sending and adjusting of sequence number.
*
* @param ipHdr
* @param hdr
* @param dataOffset
*/
private void sendHelper(IPv4Header ipHdr, TCPHeader hdr, int dataOffset)
throws SocketException {
// Adjust the sequence numbers
hdr.setSequenceNr(snd_next);
if (hdr.isFlagSynchronizeSet() || hdr.isFlagFinishedSet()) {
snd_next++;
//snd_unack++;
} else {
snd_next += hdr.getDataLength();
}
snd_max = snd_next;
// Create & send the segment
final TCPOutSegment seg =
new TCPOutSegment(ipHdr, hdr, dataBuffer, dataOffset, timeoutTicks);
seg.send(tcp);
if (!seg.isAckOnly() && !hdr.isFlagSynchronizeSet()) {
if (DEBUG) {
log.debug("Adding segment " + seg.getSeqNr() + " to unacklist");
}
unackedSegments.add(seg);
}
}
/**
* Notify a connection reset
*/
public synchronized void notifyConnectionReset() {
notifyAll();
}
/**
* @return Returns the mss.
*/
public final int getMss() {
return this.mss;
}
/**
* @param mss The mss to set.
*/
public final void setMss(int mss) {
this.mss = mss;
}
}