From d19aa4924e2018772474752c1244d9965ce2a514 Mon Sep 17 00:00:00 2001
From: Trustin Lee <trustin@gmail.com>
Date: Thu, 13 May 2010 13:40:36 +0000
Subject: [PATCH] Simplified and hardened ObjectDecoder by extending
 LengthFieldBasedFrameDecoder

---
 .../codec/serialization/ObjectDecoder.java    | 31 +++++--------------
 1 file changed, 7 insertions(+), 24 deletions(-)

diff --git a/src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoder.java b/src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoder.java
index 089a33d8ea..cc2e167b63 100644
--- a/src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoder.java
+++ b/src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoder.java
@@ -22,7 +22,7 @@ import org.jboss.netty.buffer.ChannelBuffer;
 import org.jboss.netty.buffer.ChannelBufferInputStream;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelHandlerContext;
-import org.jboss.netty.handler.codec.frame.FrameDecoder;
+import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
 
 /**
  * A decoder which deserializes the received {@link ChannelBuffer}s into Java
@@ -41,9 +41,8 @@ import org.jboss.netty.handler.codec.frame.FrameDecoder;
  * @apiviz.landmark
  * @apiviz.has org.jboss.netty.handler.codec.serialization.ObjectDecoderInputStream - - - compatible with
  */
-public class ObjectDecoder extends FrameDecoder {
+public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
 
-    private final int maxObjectSize;
     private final ClassLoader classLoader;
 
     /**
@@ -79,36 +78,20 @@ public class ObjectDecoder extends FrameDecoder {
      *                       of the serialized object
      */
     public ObjectDecoder(int maxObjectSize, ClassLoader classLoader) {
-        if (maxObjectSize <= 0) {
-            throw new IllegalArgumentException("maxObjectSize: " + maxObjectSize);
-        }
-
-        this.maxObjectSize = maxObjectSize;
+        super(maxObjectSize, 0, 4, 0, 4);
         this.classLoader = classLoader;
     }
 
     @Override
     protected Object decode(
             ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
-        if (buffer.readableBytes() < 4) {
+
+        ChannelBuffer frame = (ChannelBuffer) super.decode(ctx, channel, buffer);
+        if (frame == null) {
             return null;
         }
 
-        int dataLen = buffer.getInt(buffer.readerIndex());
-        if (dataLen <= 0) {
-            throw new StreamCorruptedException("invalid data length: " + dataLen);
-        }
-        if (dataLen > maxObjectSize) {
-            throw new StreamCorruptedException(
-                    "data length too big: " + dataLen + " (max: " + maxObjectSize + ')');
-        }
-
-        if (buffer.readableBytes() < dataLen + 4) {
-            return null;
-        }
-
-        buffer.skipBytes(4);
         return new CompactObjectInputStream(
-                new ChannelBufferInputStream(buffer, dataLen), classLoader).readObject();
+                new ChannelBufferInputStream(frame), classLoader).readObject();
     }
 }