2008-12-17 12:39:45 +01:00
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/*
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* JBoss, Home of Professional Open Source
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*
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* Copyright 2008, Red Hat Middleware LLC, and individual contributors
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* by the @author tags. See the COPYRIGHT.txt in the distribution for a
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* full listing of individual contributors.
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this software; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
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*/
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package org.jboss.netty.handler.codec.frame;
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import org.jboss.netty.buffer.ChannelBuffer;
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import org.jboss.netty.channel.Channel;
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import org.jboss.netty.channel.ChannelHandlerContext;
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/**
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* TODO Documentation
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*
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* @author The Netty Project (netty-dev@lists.jboss.org)
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* @author Trustin Lee (tlee@redhat.com)
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*
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* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
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*
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* @apiviz.landmark
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*/
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public class LengthFieldBasedFrameDecoder extends FrameDecoder {
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private final int maxFrameLength;
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private final int lengthFieldOffset;
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private final int lengthFieldLength;
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private final int lengthFieldEndOffset;
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private final int lengthAdjustment;
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2009-01-06 06:31:59 +01:00
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private volatile boolean discardingTooLongFrame;
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private volatile long tooLongFrameLength;
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private volatile long bytesToDiscard;
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2008-12-17 12:39:45 +01:00
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/**
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* Creates a new instance.
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*/
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public LengthFieldBasedFrameDecoder(
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int maxFrameLength,
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int lengthFieldOffset, int lengthFieldLength) {
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this(maxFrameLength, lengthFieldOffset, lengthFieldLength, 0);
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}
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/**
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* Creates a new instance.
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*/
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public LengthFieldBasedFrameDecoder(
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int maxFrameLength,
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int lengthFieldOffset, int lengthFieldLength, int lengthAdjustment) {
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if (maxFrameLength <= 0) {
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throw new IllegalArgumentException(
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"maxFrameLength must be a positive integer: " +
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maxFrameLength);
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}
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if (lengthFieldOffset < 0) {
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throw new IllegalArgumentException(
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"lengthFieldOffset must be a non-negative integer: " +
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lengthFieldOffset);
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}
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if (lengthFieldLength != 1 && lengthFieldLength != 2 &&
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lengthFieldLength != 3 && lengthFieldLength != 4 &&
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lengthFieldLength != 8) {
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throw new IllegalArgumentException(
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"lengthFieldLength must be either 1, 2, 3, 4, or 8: " +
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lengthFieldLength);
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}
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if (lengthFieldOffset > maxFrameLength - lengthFieldLength) {
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throw new IllegalArgumentException(
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"maxFrameLength (" + maxFrameLength + ") " +
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"must be equal to or greater than " +
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"lengthFieldOffset (" + lengthFieldOffset + ") + " +
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"lengthFieldLength (" + lengthFieldLength + ").");
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}
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this.maxFrameLength = maxFrameLength;
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this.lengthFieldOffset = lengthFieldOffset;
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this.lengthFieldLength = lengthFieldLength;
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this.lengthAdjustment = lengthAdjustment;
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lengthFieldEndOffset = lengthFieldOffset + lengthFieldLength;
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}
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@Override
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protected Object decode(
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ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
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2009-01-06 06:31:59 +01:00
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if (discardingTooLongFrame) {
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long bytesToDiscard = this.bytesToDiscard;
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int localBytesToDiscard = (int) Math.min(bytesToDiscard, buffer.readableBytes());
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buffer.skipBytes(localBytesToDiscard);
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bytesToDiscard -= localBytesToDiscard;
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this.bytesToDiscard = bytesToDiscard;
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if (bytesToDiscard == 0) {
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// Reset to the initial state and tell the handlers that
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// the frame was too large.
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discardingTooLongFrame = false;
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long tooLongFrameLength = this.tooLongFrameLength;
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this.tooLongFrameLength = 0;
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throw new TooLongFrameException(
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"Adjusted frame length exceeds " + maxFrameLength +
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": " + tooLongFrameLength);
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} else {
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// Keep discarding.
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return null;
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}
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}
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2008-12-17 12:39:45 +01:00
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if (buffer.readableBytes() < lengthFieldEndOffset) {
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return null;
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}
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int actualLengthFieldOffset = buffer.readerIndex() + lengthFieldOffset;
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long frameLength;
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switch (lengthFieldLength) {
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case 1:
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frameLength = buffer.getUnsignedByte(actualLengthFieldOffset);
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break;
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case 2:
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frameLength = buffer.getUnsignedShort(actualLengthFieldOffset);
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break;
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case 3:
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frameLength = buffer.getUnsignedMedium(actualLengthFieldOffset);
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break;
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case 4:
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frameLength = buffer.getUnsignedInt(actualLengthFieldOffset);
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break;
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case 8:
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frameLength = buffer.getLong(actualLengthFieldOffset);
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break;
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default:
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throw new Error("should not reach here");
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}
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if (frameLength < 0) {
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2009-01-06 06:31:59 +01:00
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buffer.skipBytes(lengthFieldEndOffset);
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2008-12-17 12:39:45 +01:00
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throw new CorruptedFrameException(
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"negative pre-adjustment length field: " + frameLength);
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}
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frameLength += lengthAdjustment + lengthFieldEndOffset;
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if (frameLength < lengthFieldEndOffset) {
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2009-01-06 06:31:59 +01:00
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buffer.skipBytes(lengthFieldEndOffset);
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2008-12-17 12:39:45 +01:00
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throw new CorruptedFrameException(
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"Adjusted length (" + frameLength + ") is less than " +
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lengthFieldEndOffset);
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} else if (frameLength > maxFrameLength) {
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2009-01-06 06:31:59 +01:00
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// Enter the discard mode and discard everything received so far.
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discardingTooLongFrame = true;
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tooLongFrameLength = frameLength;
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bytesToDiscard = frameLength - buffer.readableBytes();
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buffer.skipBytes(buffer.readableBytes());
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return null;
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2008-12-17 12:39:45 +01:00
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}
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// never overflows because it's less than maxFrameLength
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int frameLengthInt = (int) frameLength;
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if (buffer.readableBytes() < frameLengthInt) {
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return null;
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} else {
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return buffer.readBytes(frameLengthInt);
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}
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}
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}
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