2 files changed, 47 insertions, 1 deletions
diff --git a/src/org/traccar/ServerManager.java b/src/org/traccar/ServerManager.java
index 25ef3177a..897642551 100644
--- a/src/org/traccar/ServerManager.java
+++ b/src/org/traccar/ServerManager.java
@@ -849,7 +849,7 @@ public class ServerManager {
             serverList.add(new TrackerServer(this, new ServerBootstrap(), protocol) {
                 @Override
                 protected void addSpecificHandlers(ChannelPipeline pipeline) {
-                    pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(1024, 4, 2, 6, 0));
+                    pipeline.addLast("frameDecoder", new AtrackFrameDecoder());
                     pipeline.addLast("objectDecoder", new AtrackProtocolDecoder(ServerManager.this));
                 }
             });
diff --git a/src/org/traccar/protocol/AtrackFrameDecoder.java b/src/org/traccar/protocol/AtrackFrameDecoder.java
new file mode 100644
index 000000000..970ddc66b
--- /dev/null
+++ b/src/org/traccar/protocol/AtrackFrameDecoder.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2013 Anton Tananaev (anton.tananaev@gmail.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+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.LengthFieldBasedFrameDecoder;
+
+public class AtrackFrameDecoder extends LengthFieldBasedFrameDecoder {
+
+    private static final int KEEPALIVE_LENGTH = 12;
+    
+    public AtrackFrameDecoder() {
+        super(1024, 4, 2, 6, 0);
+    }
+    
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx,
+            Channel channel,
+            ChannelBuffer buf) throws Exception {
+        
+        // Keep alive message
+        if (buf.readableBytes() >= KEEPALIVE_LENGTH ||
+            buf.getUnsignedShort(buf.readerIndex()) == 0xfe02) {
+            channel.write(buf.readBytes(KEEPALIVE_LENGTH));
+        }
+
+        return super.decode(ctx, channel, buf);
+    }
+
+}