From b5eb588704b76a4535e656253f3d50df1b046c68 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Fri, 13 Mar 2015 15:18:57 +1300
Subject: Reimplement BCE frame decoder

---
 src/org/traccar/protocol/BceFrameDecoder.java | 31 ++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 8 deletions(-)

(limited to 'src/org/traccar')

diff --git a/src/org/traccar/protocol/BceFrameDecoder.java b/src/org/traccar/protocol/BceFrameDecoder.java
index 2bb249348..8accc02d8 100644
--- a/src/org/traccar/protocol/BceFrameDecoder.java
+++ b/src/org/traccar/protocol/BceFrameDecoder.java
@@ -18,30 +18,45 @@ package org.traccar.protocol;
 import org.jboss.netty.buffer.ChannelBuffer;
 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;
 
-public class BceFrameDecoder extends LengthFieldBasedFrameDecoder {
+public class BceFrameDecoder extends FrameDecoder {
 
     private static final int HANDSHAKE_LENGTH = 7; // "#BCE#\r\n"
-    
+
     private boolean header = true;
-    
-    public BceFrameDecoder() {
-        super(1024, 8, 2, 8 + 2 + 1, 0);
+
+    private static byte checksum(ChannelBuffer buf, int end) {
+        byte result = 0;
+        for (int i = 0; i < end; i++) {
+            result += buf.getByte(buf.readerIndex() + i);
+        }
+        return result;
     }
-    
+
     @Override
     protected Object decode(
             ChannelHandlerContext ctx,
             Channel channel,
             ChannelBuffer buf) throws Exception {
-        
+
         if (header && buf.readableBytes() >= HANDSHAKE_LENGTH) {
             buf.skipBytes(HANDSHAKE_LENGTH);
             header = false;
         }
 
-        return super.decode(ctx, channel, buf);
+        int end = 8; // IMEI
+
+        while (buf.readableBytes() >= end + 2 + 1 + 1 + 1) {
+            end += buf.getUnsignedShort(buf.readerIndex() + end) + 2;
+
+            if (buf.readableBytes() > end && checksum(buf, end) == buf.getByte(buf.readerIndex() + end)) {
+                return buf.readBytes(end + 1);
+            }
+        }
+
+        return null;
     }
 
 }
-- 
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