SnappyFrameDecoder.java — netty Source File

Source Code

/*
 * Copyright 2012 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:
 *
 *   https://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.compression;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

import static io.netty.handler.codec.compression.Snappy.validateChecksum;

/**
 * Uncompresses a {@link ByteBuf} encoded with the Snappy framing format.
 *
 * See <a href="https://github.com/google/snappy/blob/master/framing_format.txt">Snappy framing format</a>.
 *
 * Note that by default, validation of the checksum header in each chunk is
 * DISABLED for performance improvements. If performance is less of an issue,
 * or if you would prefer the safety that checksum validation brings, please
 * use the {@link #SnappyFrameDecoder(boolean)} constructor with the argument
 * set to {@code true}.
 */
public class SnappyFrameDecoder extends ByteToMessageDecoder {

    private enum ChunkType {
        STREAM_IDENTIFIER,
        COMPRESSED_DATA,
        UNCOMPRESSED_DATA,
        RESERVED_UNSKIPPABLE,
        RESERVED_SKIPPABLE
    }

    private static final int SNAPPY_IDENTIFIER_LEN = 6;
    // See https://github.com/google/snappy/blob/1.1.9/framing_format.txt#L95
    private static final int MAX_UNCOMPRESSED_DATA_SIZE = 65536 + 4;
    // See https://github.com/google/snappy/blob/1.1.9/framing_format.txt#L82
    private static final int MAX_DECOMPRESSED_DATA_SIZE = 65536;
    // See https://github.com/google/snappy/blob/1.1.9/framing_format.txt#L82
    private static final int MAX_COMPRESSED_CHUNK_SIZE = 16777216 - 1;

    private final Snappy snappy = new Snappy();
    private final boolean validateChecksums;

    private boolean started;
    private boolean corrupted;
    private int numBytesToSkip;
// ... (200 more lines)