com.heliosapm.streams.onramp.GZipDetector.java Source code

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Here is the source code for com.heliosapm.streams.onramp.GZipDetector.java

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/*
 * Copyright 2015 the original author or authors.
 *
 * Licensed 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 com.heliosapm.streams.onramp;

import java.util.List;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.compression.ZlibWrapper;

/**
 * <p>Title: GZipDetector</p>
 * <p>Description: Detects GZip content and adds a decompressor if detected</p> 
 * <p>Company: Helios Development Group LLC</p>
 * @author Whitehead (nwhitehead AT heliosdev DOT org)
 * <p><code>com.heliosapm.streams.onramp.GZipDetector</code></p>
 */

//@ChannelHandler.Sharable
public class GZipDetector extends ByteToMessageDecoder {
    /** Instance logger */
    private final Logger log = LogManager.getLogger(getClass());

    /**
     * Creates a new GZipDetector
     */
    public GZipDetector() {

    }

    /**
     * {@inheritDoc}
     * @see io.netty.handler.codec.ByteToMessageDecoder#decode(io.netty.channel.ChannelHandlerContext, io.netty.buffer.ByteBuf, java.util.List)
     */
    @Override
    protected void decode(final ChannelHandlerContext ctx, final ByteBuf buff, final List<Object> out)
            throws Exception {
        if (buff.readableBytes() > 4) {
            final int magic1 = buff.getUnsignedByte(buff.readerIndex());
            final int magic2 = buff.getUnsignedByte(buff.readerIndex() + 1);
            if (isGzip(magic1, magic2)) {
                enableGzip(ctx);
            } else {
                ctx.pipeline().remove(this);
            }
            out.add(buff.retain());
        }
    }

    private void enableGzip(final ChannelHandlerContext ctx) {
        final ChannelPipeline p = ctx.pipeline();
        try {
            //         p.addAfter("connmgr", "gzipdeflater", new JZlibEncoder(ZlibWrapper.GZIP){
            //            // TODO
            //         });            
            p.addAfter("gzipdetector", "gzipinflater", ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
            p.remove(this);
        } catch (Exception ex) {
            log.error("Failed to add gzip handlers", ex);
        }
    }

    private static boolean isGzip(final int magic1, final int magic2) {
        return magic1 == 31 && magic2 == 139;
    }
}