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More robust exception handling for incorrect length and too large frames

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This commit is contained in:
Trustin Lee 2009-01-06 05:31:59 +00:00
parent 7fa20dcb07
commit 247251420a
1 changed files with 33 additions and 5 deletions
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38
src/main/java/org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.java
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@ -43,6 +43,9 @@ public class LengthFieldBasedFrameDecoder extends FrameDecoder {
private final int lengthFieldLength; private final int lengthFieldLength;
private final int lengthFieldEndOffset; private final int lengthFieldEndOffset;
private final int lengthAdjustment; private final int lengthAdjustment;
private volatile boolean discardingTooLongFrame;
private volatile long tooLongFrameLength;
private volatile long bytesToDiscard;
/** /**
* Creates a new instance. * Creates a new instance.
@ -97,6 +100,28 @@ public class LengthFieldBasedFrameDecoder extends FrameDecoder {
@Override @Override
protected Object decode( protected Object decode(
ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception { ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
if (discardingTooLongFrame) {
long bytesToDiscard = this.bytesToDiscard;
int localBytesToDiscard = (int) Math.min(bytesToDiscard, buffer.readableBytes());
buffer.skipBytes(localBytesToDiscard);
bytesToDiscard -= localBytesToDiscard;
this.bytesToDiscard = bytesToDiscard;
if (bytesToDiscard == 0) {
// Reset to the initial state and tell the handlers that
// the frame was too large.
discardingTooLongFrame = false;
long tooLongFrameLength = this.tooLongFrameLength;
this.tooLongFrameLength = 0;
throw new TooLongFrameException(
"Adjusted frame length exceeds " + maxFrameLength +
": " + tooLongFrameLength);
} else {
// Keep discarding.
return null;
}
}
if (buffer.readableBytes() < lengthFieldEndOffset) { if (buffer.readableBytes() < lengthFieldEndOffset) {
return null; return null;
} }
@ -124,21 +149,24 @@ public class LengthFieldBasedFrameDecoder extends FrameDecoder {
} }
if (frameLength < 0) { if (frameLength < 0) {
buffer.skipBytes(actualLengthFieldOffset + lengthFieldLength); buffer.skipBytes(lengthFieldEndOffset);
throw new CorruptedFrameException( throw new CorruptedFrameException(
"negative pre-adjustment length field: " + frameLength); "negative pre-adjustment length field: " + frameLength);
} }
frameLength += lengthAdjustment + lengthFieldEndOffset; frameLength += lengthAdjustment + lengthFieldEndOffset;
if (frameLength < lengthFieldEndOffset) { if (frameLength < lengthFieldEndOffset) {
buffer.skipBytes(actualLengthFieldOffset + lengthFieldLength); buffer.skipBytes(lengthFieldEndOffset);
throw new CorruptedFrameException( throw new CorruptedFrameException(
"Adjusted length (" + frameLength + ") is less than " + "Adjusted length (" + frameLength + ") is less than " +
lengthFieldEndOffset); lengthFieldEndOffset);
} else if (frameLength > maxFrameLength) { } else if (frameLength > maxFrameLength) {
throw new TooLongFrameException( // Enter the discard mode and discard everything received so far.
"Adjusted length exceeds " + maxFrameLength + ": " + discardingTooLongFrame = true;
frameLength); tooLongFrameLength = frameLength;
bytesToDiscard = frameLength - buffer.readableBytes();
buffer.skipBytes(buffer.readableBytes());
return null;
} }
// never overflows because it's less than maxFrameLength // never overflows because it's less than maxFrameLength