/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.handler.codec.http.websocketx.extensions.compression;
import static io.netty.handler.codec.http.websocketx.extensions.compression.PerMessageDeflateDecoder.*;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.CompositeByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.CodecException;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.compression.ZlibWrapper;
import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
import io.netty.handler.codec.http.websocketx.ContinuationWebSocketFrame;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionEncoder;
import io.netty.util.ReferenceCountUtil;
import java.util.List;
/**
* Deflate implementation of a payload compressor for
* <tt>io.netty.handler.codec.http.websocketx.WebSocketFrame</tt>.
*/
abstract class DeflateEncoder extends WebSocketExtensionEncoder {
private final int compressionLevel;
private final int windowSize;
private final boolean noContext;
private EmbeddedChannel encoder;
/**
* Constructor
* @param compressionLevel compression level of the compressor.
* @param windowSize maximum size of the window compressor buffer.
* @param noContext true to disable context takeover.
*/
public DeflateEncoder(int compressionLevel, int windowSize, boolean noContext) {
this.compressionLevel = compressionLevel;
this.windowSize = windowSize;
this.noContext = noContext;
}
/**
* @param msg the current frame.
* @return the rsv bits to set in the compressed frame.
*/
protected abstract int rsv(WebSocketFrame msg);
/**
* @param msg the current frame.
* @return true if compressed payload tail needs to be removed.
*/
protected abstract boolean removeFrameTail(WebSocketFrame msg);
@Override
protected void encode(ChannelHandlerContext ctx, WebSocketFrame msg,
List<Object> out) throws Exception {
if (encoder == null) {
encoder = new EmbeddedChannel(ZlibCodecFactory.newZlibEncoder(
ZlibWrapper.NONE, compressionLevel, windowSize, 8));
}
encoder.writeOutbound(msg.content().retain());
CompositeByteBuf fullCompressedContent = ctx.alloc().compositeBuffer();
for (;;) {
ByteBuf partCompressedContent = encoder.readOutbound();
if (partCompressedContent == null) {
break;
}
if (!partCompressedContent.isReadable()) {
partCompressedContent.release();
continue;
}
fullCompressedContent.addComponent(partCompressedContent);
fullCompressedContent.writerIndex(fullCompressedContent.writerIndex() +
partCompressedContent.readableBytes());
}
if (fullCompressedContent.numComponents() <= 0) {
fullCompressedContent.release();
throw new CodecException("cannot read compressed buffer");
}
if (msg.isFinalFragment() && noContext) {
cleanup();
}
ByteBuf compressedContent;
if (removeFrameTail(msg)) {
int realLength = fullCompressedContent.readableBytes() - FRAME_TAIL.length;
compressedContent = fullCompressedContent.slice(0, realLength);
} else {
compressedContent = fullCompressedContent;
}
WebSocketFrame outMsg;
if (msg instanceof TextWebSocketFrame) {
outMsg = new TextWebSocketFrame(msg.isFinalFragment(), rsv(msg), compressedContent);
} else if (msg instanceof BinaryWebSocketFrame) {
outMsg = new BinaryWebSocketFrame(msg.isFinalFragment(), rsv(msg), compressedContent);
} else if (msg instanceof ContinuationWebSocketFrame) {
outMsg = new ContinuationWebSocketFrame(msg.isFinalFragment(), rsv(msg), compressedContent);
} else {
throw new CodecException("unexpected frame type: " + msg.getClass().getName());
}
out.add(outMsg);
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
cleanup();
super.handlerRemoved(ctx);
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
cleanup();
super.channelInactive(ctx);
}
private void cleanup() {
if (encoder != null) {
// Clean-up the previous encoder if not cleaned up correctly.
if (encoder.finish()) {
for (;;) {
ByteBuf buf = encoder.readOutbound();
if (buf == null) {
break;
}
// Release the buffer
buf.release();
}
}
encoder = null;
}
}
}