//
// ========================================================================
// Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.websocket.common.extensions.compress;
import java.nio.ByteBuffer;
import java.util.Queue;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
import java.util.zip.ZipException;
import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.ConcurrentArrayQueue;
import org.eclipse.jetty.util.IteratingCallback;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
import org.eclipse.jetty.websocket.api.BadPayloadException;
import org.eclipse.jetty.websocket.api.BatchMode;
import org.eclipse.jetty.websocket.api.WriteCallback;
import org.eclipse.jetty.websocket.api.extensions.Frame;
import org.eclipse.jetty.websocket.common.OpCode;
import org.eclipse.jetty.websocket.common.extensions.AbstractExtension;
import org.eclipse.jetty.websocket.common.frames.DataFrame;
public abstract class CompressExtension extends AbstractExtension
{
protected static final byte[] TAIL_BYTES = new byte[]{0x00, 0x00, (byte)0xFF, (byte)0xFF};
private static final Logger LOG = Log.getLogger(CompressExtension.class);
/** Never drop tail bytes 0000FFFF, from any frame type */
protected static final int TAIL_DROP_NEVER = 0;
/** Always drop tail bytes 0000FFFF, from all frame types */
protected static final int TAIL_DROP_ALWAYS = 1;
/** Only drop tail bytes 0000FFFF, from fin==true frames */
protected static final int TAIL_DROP_FIN_ONLY = 2;
/** Always set RSV flag, on all frame types */
protected static final int RSV_USE_ALWAYS = 0;
/**
* Only set RSV flag on first frame in multi-frame messages.
* <p>
* Note: this automatically means no-continuation frames have
* the RSV bit set
*/
protected static final int RSV_USE_ONLY_FIRST = 1;
private final Queue<FrameEntry> entries = new ConcurrentArrayQueue<>();
private final IteratingCallback flusher = new Flusher();
private final Deflater compressor;
private final Inflater decompressor;
private int tailDrop = TAIL_DROP_NEVER;
private int rsvUse = RSV_USE_ALWAYS;
protected CompressExtension()
{
compressor = new Deflater(Deflater.BEST_COMPRESSION, true);
decompressor = new Inflater(true);
tailDrop = getTailDropMode();
rsvUse = getRsvUseMode();
}
public Deflater getDeflater()
{
return compressor;
}
public Inflater getInflater()
{
return decompressor;
}
/**
* Indicates use of RSV1 flag for indicating deflation is in use.
*/
@Override
public boolean isRsv1User()
{
return true;
}
/**
* Return the mode of operation for dropping (or keeping) tail bytes in frames generated by compress (outgoing)
*
* @return either {@link #TAIL_DROP_ALWAYS}, {@link #TAIL_DROP_FIN_ONLY}, or {@link #TAIL_DROP_NEVER}
*/
abstract int getTailDropMode();
/**
* Return the mode of operation for RSV flag use in frames generate by compress (outgoing)
*
* @return either {@link #RSV_USE_ALWAYS} or {@link #RSV_USE_ONLY_FIRST}
*/
abstract int getRsvUseMode();
protected void forwardIncoming(Frame frame, ByteAccumulator accumulator)
{
DataFrame newFrame = new DataFrame(frame);
// Unset RSV1 since it's not compressed anymore.
newFrame.setRsv1(false);
ByteBuffer buffer = getBufferPool().acquire(accumulator.getLength(), false);
try
{
BufferUtil.flipToFill(buffer);
accumulator.transferTo(buffer);
newFrame.setPayload(buffer);
nextIncomingFrame(newFrame);
}
finally
{
getBufferPool().release(buffer);
}
}
protected ByteAccumulator decompress(byte[] input)
{
// Since we don't track text vs binary vs continuation state, just grab whatever is the greater value.
int maxSize = Math.max(getPolicy().getMaxTextMessageSize(), getPolicy().getMaxBinaryMessageBufferSize());
ByteAccumulator accumulator = new ByteAccumulator(maxSize);
decompressor.setInput(input, 0, input.length);
if (LOG.isDebugEnabled())
LOG.debug("Decompressing {} bytes", input.length);
try
{
// It is allowed to send DEFLATE blocks with BFINAL=1.
// For such blocks, getRemaining() will be > 0 but finished()
// will be true, so we need to check for both.
// When BFINAL=0, finished() will always be false and we only
// check the remaining bytes.
while (decompressor.getRemaining() > 0 && !decompressor.finished())
{
byte[] output = new byte[Math.min(input.length * 2, 32 * 1024)];
int decompressed = decompressor.inflate(output);
if (decompressed == 0)
{
if (decompressor.needsInput())
{
throw new BadPayloadException("Unable to inflate frame, not enough input on frame");
}
if (decompressor.needsDictionary())
{
throw new BadPayloadException("Unable to inflate frame, frame erroneously says it needs a dictionary");
}
}
else
{
accumulator.addChunk(output, 0, decompressed);
}
}
if (LOG.isDebugEnabled())
LOG.debug("Decompressed {}->{} bytes", input.length, accumulator.getLength());
return accumulator;
}
catch (DataFormatException x)
{
throw new BadPayloadException(x);
}
}
@Override
public void outgoingFrame(Frame frame, WriteCallback callback, BatchMode batchMode)
{
// We use a queue and an IteratingCallback to handle concurrency.
// We must compress and write atomically, otherwise the compression
// context on the other end gets confused.
if (flusher.isFailed())
{
notifyCallbackFailure(callback, new ZipException());
return;
}
FrameEntry entry = new FrameEntry(frame, callback, batchMode);
if (LOG.isDebugEnabled())
LOG.debug("Queuing {}", entry);
entries.offer(entry);
flusher.iterate();
}
protected void notifyCallbackSuccess(WriteCallback callback)
{
try
{
if (callback != null)
callback.writeSuccess();
}
catch (Throwable x)
{
if (LOG.isDebugEnabled())
LOG.debug("Exception while notifying success of callback " + callback, x);
}
}
protected void notifyCallbackFailure(WriteCallback callback, Throwable failure)
{
try
{
if (callback != null)
callback.writeFailed(failure);
}
catch (Throwable x)
{
if (LOG.isDebugEnabled())
LOG.debug("Exception while notifying failure of callback " + callback, x);
}
}
@Override
public String toString()
{
return getClass().getSimpleName();
}
private static class FrameEntry
{
private final Frame frame;
private final WriteCallback callback;
private final BatchMode batchMode;
private FrameEntry(Frame frame, WriteCallback callback, BatchMode batchMode)
{
this.frame = frame;
this.callback = callback;
this.batchMode = batchMode;
}
@Override
public String toString()
{
return frame.toString();
}
}
private class Flusher extends IteratingCallback implements WriteCallback
{
private static final int INPUT_BUFSIZE = 32 * 1024;
private FrameEntry current;
private ByteBuffer payload;
private boolean finished = true;
@Override
protected Action process() throws Exception
{
if (finished)
{
current = entries.poll();
LOG.debug("Processing {}", current);
if (current == null)
return Action.IDLE;
deflate(current);
}
else
{
compress(current, false);
}
return Action.SCHEDULED;
}
private void deflate(FrameEntry entry)
{
Frame frame = entry.frame;
BatchMode batchMode = entry.batchMode;
if (OpCode.isControlFrame(frame.getOpCode()) || !frame.hasPayload())
{
nextOutgoingFrame(frame, this, batchMode);
return;
}
compress(entry, true);
}
private void compress(FrameEntry entry, boolean first)
{
// Get a chunk of the payload to avoid to blow
// the heap if the payload is a huge mapped file.
Frame frame = entry.frame;
ByteBuffer data = frame.getPayload();
int remaining = data.remaining();
int inputLength = Math.min(remaining, INPUT_BUFSIZE);
if (LOG.isDebugEnabled())
LOG.debug("Compressing {}: {} bytes in {} bytes chunk", entry, remaining, inputLength);
// Avoid to copy the bytes if the ByteBuffer
// is backed by an array.
int inputOffset;
byte[] input;
if (data.hasArray())
{
input = data.array();
int position = data.position();
inputOffset = position + data.arrayOffset();
data.position(position + inputLength);
}
else
{
input = new byte[inputLength];
inputOffset = 0;
data.get(input, 0, inputLength);
}
finished = inputLength == remaining;
compressor.setInput(input, inputOffset, inputLength);
// Use an additional space in case the content is not compressible.
byte[] output = new byte[inputLength + 64];
int outputOffset = 0;
int outputLength = 0;
while (true)
{
int space = output.length - outputOffset;
int compressed = compressor.deflate(output, outputOffset, space, Deflater.SYNC_FLUSH);
outputLength += compressed;
if (compressed < space)
{
// Everything was compressed.
break;
}
else
{
// The compressed output is bigger than the uncompressed input.
byte[] newOutput = new byte[output.length * 2];
System.arraycopy(output, 0, newOutput, 0, output.length);
outputOffset += output.length;
output = newOutput;
}
}
boolean fin = frame.isFin() && finished;
// Handle tail bytes generated by SYNC_FLUSH.
if(tailDrop == TAIL_DROP_ALWAYS) {
payload = ByteBuffer.wrap(output, 0, outputLength - TAIL_BYTES.length);
} else if(tailDrop == TAIL_DROP_FIN_ONLY) {
payload = ByteBuffer.wrap(output, 0, outputLength - (fin?TAIL_BYTES.length:0));
} else {
// always include
payload = ByteBuffer.wrap(output, 0, outputLength);
}
if (LOG.isDebugEnabled())
{
LOG.debug("Compressed {}: {}->{} chunk bytes",entry,inputLength,outputLength);
}
boolean continuation = frame.getType().isContinuation() || !first;
DataFrame chunk = new DataFrame(frame, continuation);
if(rsvUse == RSV_USE_ONLY_FIRST) {
chunk.setRsv1(!continuation);
} else {
// always set
chunk.setRsv1(true);
}
chunk.setPayload(payload);
chunk.setFin(fin);
nextOutgoingFrame(chunk, this, entry.batchMode);
}
@Override
protected void onCompleteSuccess()
{
// This IteratingCallback never completes.
}
@Override
protected void onCompleteFailure(Throwable x)
{
// Fail all the frames in the queue.
FrameEntry entry;
while ((entry = entries.poll()) != null)
notifyCallbackFailure(entry.callback, x);
}
@Override
public void writeSuccess()
{
if (finished)
notifyCallbackSuccess(current.callback);
succeeded();
}
@Override
public void writeFailed(Throwable x)
{
notifyCallbackFailure(current.callback, x);
// If something went wrong, very likely the compression context
// will be invalid, so we need to fail this IteratingCallback.
failed(x);
}
}
}