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Resolved issue: NETTY-95 Length-prefixed frame decoder

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* Added LengthFieldBasedFrameDecoder
* Added CorruptedFrameException
This commit is contained in:
Trustin Lee 2008-12-17 11:39:45 +00:00
parent 2cc2124653
commit afcd2b8315
2 changed files with 217 additions and 0 deletions
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67
src/main/java/org/jboss/netty/handler/codec/frame/CorruptedFrameException.java Normal file
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/*
* JBoss, Home of Professional Open Source
*
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.netty.handler.codec.frame;
/**
* An {@link Exception} which is thrown when the received frame data can not
* be decoded by a {@link FrameDecoder} implementation.
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*
* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
*
* @apiviz.hidden
*/
public class CorruptedFrameException extends Exception {
private static final long serialVersionUID = 3918052232492988408L;
/**
* Creates a new instance.
*/
public CorruptedFrameException() {
super();
}
/**
* Creates a new instance.
*/
public CorruptedFrameException(String message, Throwable cause) {
super(message, cause);
}
/**
* Creates a new instance.
*/
public CorruptedFrameException(String message) {
super(message);
}
/**
* Creates a new instance.
*/
public CorruptedFrameException(Throwable cause) {
super(cause);
}
}

150
src/main/java/org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.java Normal file
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/*
* JBoss, Home of Professional Open Source
*
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.netty.handler.codec.frame;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
/**
* TODO Documentation
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*
* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
*
* @apiviz.landmark
*/
public class LengthFieldBasedFrameDecoder extends FrameDecoder {
private final int maxFrameLength;
private final int lengthFieldOffset;
private final int lengthFieldLength;
private final int lengthFieldEndOffset;
private final int lengthAdjustment;
/**
* Creates a new instance.
*/
public LengthFieldBasedFrameDecoder(
int maxFrameLength,
int lengthFieldOffset, int lengthFieldLength) {
this(maxFrameLength, lengthFieldOffset, lengthFieldLength, 0);
}
/**
* Creates a new instance.
*/
public LengthFieldBasedFrameDecoder(
int maxFrameLength,
int lengthFieldOffset, int lengthFieldLength, int lengthAdjustment) {
if (maxFrameLength <= 0) {
throw new IllegalArgumentException(
"maxFrameLength must be a positive integer: " +
maxFrameLength);
}
if (lengthFieldOffset < 0) {
throw new IllegalArgumentException(
"lengthFieldOffset must be a non-negative integer: " +
lengthFieldOffset);
}
if (lengthFieldLength != 1 && lengthFieldLength != 2 &&
lengthFieldLength != 3 && lengthFieldLength != 4 &&
lengthFieldLength != 8) {
throw new IllegalArgumentException(
"lengthFieldLength must be either 1, 2, 3, 4, or 8: " +
lengthFieldLength);
}
if (lengthFieldOffset > maxFrameLength - lengthFieldLength) {
throw new IllegalArgumentException(
"maxFrameLength (" + maxFrameLength + ") " +
"must be equal to or greater than " +
"lengthFieldOffset (" + lengthFieldOffset + ") + " +
"lengthFieldLength (" + lengthFieldLength + ").");
}
this.maxFrameLength = maxFrameLength;
this.lengthFieldOffset = lengthFieldOffset;
this.lengthFieldLength = lengthFieldLength;
this.lengthAdjustment = lengthAdjustment;
lengthFieldEndOffset = lengthFieldOffset + lengthFieldLength;
}
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
if (buffer.readableBytes() < lengthFieldEndOffset) {
return null;
}
int actualLengthFieldOffset = buffer.readerIndex() + lengthFieldOffset;
long frameLength;
switch (lengthFieldLength) {
case 1:
frameLength = buffer.getUnsignedByte(actualLengthFieldOffset);
break;
case 2:
frameLength = buffer.getUnsignedShort(actualLengthFieldOffset);
break;
case 3:
frameLength = buffer.getUnsignedMedium(actualLengthFieldOffset);
break;
case 4:
frameLength = buffer.getUnsignedInt(actualLengthFieldOffset);
break;
case 8:
frameLength = buffer.getLong(actualLengthFieldOffset);
break;
default:
throw new Error("should not reach here");
}
if (frameLength < 0) {
throw new CorruptedFrameException(
"negative pre-adjustment length field: " + frameLength);
}
frameLength += lengthAdjustment + lengthFieldEndOffset;
if (frameLength < lengthFieldEndOffset) {
throw new CorruptedFrameException(
"Adjusted length (" + frameLength + ") is less than " +
lengthFieldEndOffset);
} else if (frameLength > maxFrameLength) {
throw new TooLongFrameException(
"Adjusted length exceeds " + maxFrameLength + ": " +
frameLength);
}
// never overflows because it's less than maxFrameLength
int frameLengthInt = (int) frameLength;
if (buffer.readableBytes() < frameLengthInt) {
return null;
} else {
return buffer.readBytes(frameLengthInt);
}
}
}