Use heuristics for H02 message length

2 files changed, 14 insertions, 4 deletions

diff --git a/src/org/traccar/protocol/H02FrameDecoder.java b/src/org/traccar/protocol/H02FrameDecoder.java
index feba8033d..2a005e760 100644
--- a/src/org/traccar/protocol/H02FrameDecoder.java
+++ b/src/org/traccar/protocol/H02FrameDecoder.java
@@ -22,6 +22,9 @@ import org.jboss.netty.handler.codec.frame.FrameDecoder;
 
 public class H02FrameDecoder extends FrameDecoder {
 
+    private static final int MESSAGE_SHORT = 32;
+    private static final int MESSAGE_LONG = 45;
+
     private int messageLength;
 
     public H02FrameDecoder(int messageLength) {
@@ -49,10 +52,17 @@ public class H02FrameDecoder extends FrameDecoder {
                 return buf.readBytes(index + 1 - buf.readerIndex());
             }
 
-        } else if (marker == '$' && buf.readableBytes() >= messageLength) {
+        } else if (marker == '$') {
 
-            // Return binary message
-            return buf.readBytes(messageLength);
+            if (messageLength > 0 && buf.readableBytes() >= messageLength) {
+                return buf.readBytes(messageLength);
+            } else if (buf.readableBytes() >= MESSAGE_SHORT) {
+                if (buf.getUnsignedByte(buf.readerIndex() + MESSAGE_SHORT - 1) == 0) {
+                    return buf.readBytes(MESSAGE_SHORT);
+                } else if (buf.readableBytes() >= MESSAGE_LONG) {
+                    return buf.readBytes(MESSAGE_LONG);
+                }
+            }
 
         }
 
diff --git a/src/org/traccar/protocol/H02Protocol.java b/src/org/traccar/protocol/H02Protocol.java
index 06ac2a6fa..089721aed 100644
--- a/src/org/traccar/protocol/H02Protocol.java
+++ b/src/org/traccar/protocol/H02Protocol.java
@@ -43,7 +43,7 @@ public class H02Protocol extends BaseProtocol {
         serverList.add(new TrackerServer(new ServerBootstrap(), getName()) {
             @Override
             protected void addSpecificHandlers(ChannelPipeline pipeline) {
-                int messageLength = Context.getConfig().getInteger(getName() + ".messageLength", 32);
+                int messageLength = Context.getConfig().getInteger(getName() + ".messageLength");
                 pipeline.addLast("frameDecoder", new H02FrameDecoder(messageLength));
                 pipeline.addLast("stringEncoder", new StringEncoder());
                 pipeline.addLast("objectEncoder", new H02ProtocolEncoder());