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The Netty project is an effort to provide an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.

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/*
 * Copyright 2013 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 org.jboss.netty.handler.codec.spdy;

import static org.jboss.netty.handler.codec.spdy.SpdyCodecUtil.*;

import java.util.zip.DataFormatException;
import java.util.zip.Inflater;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;

class SpdyHeaderBlockZlibDecoder extends SpdyHeaderBlockRawDecoder {

    private final int version;
    private final byte[] out = new byte[8192];
    private final Inflater decompressor = new Inflater();

    private ChannelBuffer decompressed;

    public SpdyHeaderBlockZlibDecoder(int version, int maxHeaderSize) {
        super(version, maxHeaderSize);
        this.version = version;
    }

    @Override
    void decode(ChannelBuffer encoded, SpdyHeadersFrame frame) throws Exception {
        setInput(encoded);

        int numBytes;
        do {
            numBytes = decompress(frame);
        } while (!decompressed.readable() && numBytes > 0);
    }

    private void setInput(ChannelBuffer compressed) {
        byte[] in = new byte[compressed.readableBytes()];
        compressed.readBytes(in);
        decompressor.setInput(in);
    }

    private int decompress(SpdyHeadersFrame frame) throws Exception {
        if (decompressed == null) {
            decompressed = ChannelBuffers.dynamicBuffer(8192);
        }

        try {
            int numBytes = decompressor.inflate(out);
            if (numBytes == 0 && decompressor.needsDictionary()) {
                if (version < 3) {
                    decompressor.setDictionary(SPDY2_DICT);
                } else {
                    decompressor.setDictionary(SPDY_DICT);
                }
                numBytes = decompressor.inflate(out);
            }
            if (frame != null) {
                decompressed.writeBytes(out, 0, numBytes);
                super.decode(decompressed, frame);
                decompressed.discardReadBytes();
            }
            return numBytes;
        } catch (DataFormatException e) {
            throw new SpdyProtocolException(
                    "Received invalid header block", e);
        }
    }

    @Override
    void reset() {
        decompressed = null;
        super.reset();
    }

    @Override
    public void end() {
        decompressed = null;
        decompressor.end();
        super.end();
    }
}