/*
* $Id$
*
* 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.LinkedList;
import org.apache.log4j.Logger;
import org.jnode.net.SocketBuffer;
import org.jnode.net.ipv4.IPv4Header;
/**
* @author Ewout Prangsma (epr@users.sourceforge.net)
*/
public class TCPInChannel {
/**
* My logger
*/
private static final Logger log = Logger.getLogger(TCPInChannel.class);
/**
* Segments that have been received, but are out of order
*/
private final LinkedList<TCPInSegment> futureSegments = new LinkedList<TCPInSegment>();
/**
* The next expected sequence number
*/
private int rcv_next;
/**
* The input data buffer
*/
private final TCPDataBuffer dataBuffer;
/**
* The control block I belong to
*/
private final TCPControlBlock controlBlock;
/**
* Has a FIN been received?
*/
private boolean finReceived;
/**
* Create a new instance
*/
public TCPInChannel(TCPControlBlock controlBlock) {
this.controlBlock = controlBlock;
this.dataBuffer = new TCPDataBuffer(TCPConstants.TCP_BUFFER_SIZE);
this.finReceived = false;
}
/**
* Initialize the initial sequence nr from the foreign side.
*
* @param hdr
*/
public void initISN(TCPHeader hdr) {
this.rcv_next = hdr.getSequenceNr() + 1;
}
/**
* Process received data
*
* @param ipHdr
* @param hdr
* @param skbuf
*/
public void processData(IPv4Header ipHdr, TCPHeader hdr, SocketBuffer skbuf) throws SocketException {
final int seqNr = hdr.getSequenceNr();
// Check the seq-nr
if (TCPUtils.SEQ_LT(seqNr, rcv_next)) {
// Ignore segment, we've already got it
log.debug("Ignoring segment because we already got it");
return;
}
if (hdr.isFlagFinishedSet()) {
finReceived = true;
}
if (seqNr == rcv_next) {
// This segment is the first expected segment
if (processNextSegment(hdr, skbuf)) {
// See if we have the next segment already in the list
TCPInSegment seg;
while ((seg = findNextSegment()) != null) {
// Next segment was in the list
if (processNextSegment(seg.hdr, seg.skbuf)) {
// Segment fully processed, remove it from the list
futureSegments.remove(seg);
} else {
// No space left, stop sending data to application
break;
}
}
}
}
}
/**
* Process the given segment (that must be the next expected segment). The data will be send to
* the input data buffer, if there is enough space left in the buffer.
*
* @param hdr
* @param skbuf
* @return True if the segment has been fully processed, false otherwise.
* @throws SocketException
*/
private synchronized boolean processNextSegment(TCPHeader hdr, SocketBuffer skbuf) throws SocketException {
final int seqNr = hdr.getSequenceNr();
if (seqNr != rcv_next) {
throw new IllegalArgumentException("hdr.seqNr != rcv_next");
}
// This segment is the first expected segment
// Sent it to the application if there is enough space
final int dataLength = hdr.getDataLength();
if (dataLength > dataBuffer.getFreeSize()) {
// Not enough free space, ignore this segment, it will be retransmitted.
log.debug("nextSegment dropped due to lack of space");
return false;
} else {
// Enough space, save
if (dataLength > 0) {
dataBuffer.add(skbuf, 0, dataLength);
// Update rcv_next
rcv_next += dataLength;
}
final boolean fin = hdr.isFlagFinishedSet();
final boolean syn = hdr.isFlagSynchronizeSet();
if (syn || fin) {
// SYN & FIN take up 1 seq-nr
rcv_next++;
}
if ((dataLength > 0) || fin) {
// And ACK it
controlBlock.sendACK(0, rcv_next);
}
// Notify threads blocked in read
notifyAll();
// We've processed it fully
return true;
}
}
/**
* Find the segment that has sequnce-nr equal to rcv_next.
*
* @return The segment or null if not found
*/
private TCPInSegment findNextSegment() {
for (TCPInSegment seg : futureSegments) {
if (seg.getSeqNr() == rcv_next) {
return seg;
}
}
return null;
}
/**
* Return the number of available bytes in the input buffer.
*/
public int available() {
return dataBuffer.getUsed();
}
public int getBufferSize() {
return dataBuffer.getLength();
}
/**
* Read data from the input buffer up to len bytes long. Block until there is data available.
*
* @param dst
* @param off
* @param len
* @return The number of bytes read
*/
public synchronized int read(byte[] dst, int off, int len) throws SocketException {
while ((dataBuffer.getUsed() == 0) && !controlBlock.isReset() && !isEOF()) {
try {
wait();
} catch (InterruptedException ex) {
// Ignore
}
}
if (controlBlock.isReset()) {
throw new SocketException("Connection reset");
} else if (isEOF()) {
return -1;
} else {
return dataBuffer.read(dst, off, len);
}
}
/**
* Notify a connection reset
*/
public synchronized void notifyConnectionReset() {
notifyAll();
}
/**
* @return Returns the rcv_next.
*/
public final int getRcvNext() {
return this.rcv_next;
}
/**
* Has the End of the InputChannel been reached?
*
* @return True if EOF has been reached, false otherwise
*/
protected final boolean isEOF() {
if (!finReceived) {
// Other site has not closed
return false;
}
if (dataBuffer.getUsed() > 0) {
// Still data in databuffer
return false;
}
if (!futureSegments.isEmpty()) {
// Still future segments
return false;
}
// TODO No other requirements here?????
return true;
}
}