All Downloads are FREE. Search and download functionalities are using the official Maven repository.

io.netty.handler.codec.compression.FastLzFrameDecoder Maven / Gradle / Ivy

Go to download

This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 34.0.0.Final
Show newest version
/*
 * 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:
 *
 *   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 java.util.zip.Adler32;
import java.util.zip.Checksum;

import static io.netty.handler.codec.compression.FastLz.BLOCK_TYPE_COMPRESSED;
import static io.netty.handler.codec.compression.FastLz.BLOCK_WITH_CHECKSUM;
import static io.netty.handler.codec.compression.FastLz.MAGIC_NUMBER;
import static io.netty.handler.codec.compression.FastLz.decompress;

/**
 * Uncompresses a {@link ByteBuf} encoded by {@link FastLzFrameEncoder} using the FastLZ algorithm.
 *
 * See FastLZ format.
 */
public class FastLzFrameDecoder extends ByteToMessageDecoder {
    /**
     * Current state of decompression.
     */
    private enum State {
        INIT_BLOCK,
        INIT_BLOCK_PARAMS,
        DECOMPRESS_DATA,
        CORRUPTED
    }

    private State currentState = State.INIT_BLOCK;

    /**
     * Underlying checksum calculator in use.
     */
    private final ByteBufChecksum checksum;

    /**
     * Length of current received chunk of data.
     */
    private int chunkLength;

    /**
     * Original of current received chunk of data.
     * It is equal to {@link #chunkLength} for non compressed chunks.
     */
    private int originalLength;

    /**
     * Indicates is this chunk compressed or not.
     */
    private boolean isCompressed;

    /**
     * Indicates is this chunk has checksum or not.
     */
    private boolean hasChecksum;

    /**
     * Checksum value of current received chunk of data which has checksum.
     */
    private int currentChecksum;

    /**
     * Creates the fastest FastLZ decoder without checksum calculation.
     */
    public FastLzFrameDecoder() {
        this(false);
    }

    /**
     * Creates a FastLZ decoder with calculation of checksums as specified.
     *
     * @param validateChecksums
     *        If true, the checksum field will be validated against the actual
     *        uncompressed data, and if the checksums do not match, a suitable
     *        {@link DecompressionException} will be thrown.
     *        Note, that in this case decoder will use {@link java.util.zip.Adler32}
     *        as a default checksum calculator.
     */
    public FastLzFrameDecoder(boolean validateChecksums) {
        this(validateChecksums ? new Adler32() : null);
    }

    /**
     * Creates a FastLZ decoder with specified checksum calculator.
     *
     * @param checksum
     *        the {@link Checksum} instance to use to check data for integrity.
     *        You may set {@code null} if you do not want to validate checksum of each block.
     */
    public FastLzFrameDecoder(Checksum checksum) {
        this.checksum = checksum == null ? null : ByteBufChecksum.wrapChecksum(checksum);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception {
        try {
            switch (currentState) {
            case INIT_BLOCK:
                if (in.readableBytes() < 4) {
                    break;
                }

                final int magic = in.readUnsignedMedium();
                if (magic != MAGIC_NUMBER) {
                    throw new DecompressionException("unexpected block identifier");
                }

                final byte options = in.readByte();
                isCompressed = (options & 0x01) == BLOCK_TYPE_COMPRESSED;
                hasChecksum = (options & 0x10) == BLOCK_WITH_CHECKSUM;

                currentState = State.INIT_BLOCK_PARAMS;
                // fall through
            case INIT_BLOCK_PARAMS:
                if (in.readableBytes() < 2 + (isCompressed ? 2 : 0) + (hasChecksum ? 4 : 0)) {
                    break;
                }
                currentChecksum = hasChecksum ? in.readInt() : 0;
                chunkLength = in.readUnsignedShort();
                originalLength = isCompressed ? in.readUnsignedShort() : chunkLength;

                currentState = State.DECOMPRESS_DATA;
                // fall through
            case DECOMPRESS_DATA:
                final int chunkLength = this.chunkLength;
                if (in.readableBytes() < chunkLength) {
                    break;
                }

                final int idx = in.readerIndex();
                final int originalLength = this.originalLength;

                ByteBuf output = null;

                try {
                    if (isCompressed) {

                        output = ctx.alloc().buffer(originalLength);
                        int outputOffset = output.writerIndex();
                        final int decompressedBytes = decompress(in, idx, chunkLength,
                                output, outputOffset, originalLength);
                        if (originalLength != decompressedBytes) {
                            throw new DecompressionException(String.format(
                                    "stream corrupted: originalLength(%d) and actual length(%d) mismatch",
                                    originalLength, decompressedBytes));
                        }
                        output.writerIndex(output.writerIndex() + decompressedBytes);
                    } else {
                        output = in.retainedSlice(idx, chunkLength);
                    }

                    final ByteBufChecksum checksum = this.checksum;
                    if (hasChecksum && checksum != null) {
                        checksum.reset();
                        checksum.update(output, output.readerIndex(), output.readableBytes());
                        final int checksumResult = (int) checksum.getValue();
                        if (checksumResult != currentChecksum) {
                            throw new DecompressionException(String.format(
                                    "stream corrupted: mismatching checksum: %d (expected: %d)",
                                    checksumResult, currentChecksum));
                        }
                    }

                    if (output.readableBytes() > 0) {
                        out.add(output);
                    } else {
                        output.release();
                    }
                    output = null;
                    in.skipBytes(chunkLength);

                    currentState = State.INIT_BLOCK;
                } finally {
                    if (output != null) {
                        output.release();
                    }
                }
                break;
            case CORRUPTED:
                in.skipBytes(in.readableBytes());
                break;
            default:
                throw new IllegalStateException();
            }
        } catch (Exception e) {
            currentState = State.CORRUPTED;
            throw e;
        }
    }
}
    

    

    

            

    

            



    
    






    
© 2015 - 2024 Weber Informatics LLC | Privacy Policy