From 04982b2acfa6e79c7ebccb814457ab0eaab86f9f Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Tue, 13 Jan 2015 15:53:05 +1300
Subject: Add frame decoder for Ulbotech

---
 src/org/traccar/ServerManager.java                 |  5 +-
 src/org/traccar/protocol/UlbotechFrameDecoder.java | 61 ++++++++++++++++++++++
 2 files changed, 62 insertions(+), 4 deletions(-)
 create mode 100644 src/org/traccar/protocol/UlbotechFrameDecoder.java

diff --git a/src/org/traccar/ServerManager.java b/src/org/traccar/ServerManager.java
index ca698f977..95c1d1f71 100644
--- a/src/org/traccar/ServerManager.java
+++ b/src/org/traccar/ServerManager.java
@@ -1274,14 +1274,11 @@ public class ServerManager {
     }
 
     private void initUlbotechServer(final String protocol) throws SQLException {
-
-        // TODO: Waiting for feedback from manufacturer
-
         if (isProtocolEnabled(properties, protocol)) {
             serverList.add(new TrackerServer(this, new ServerBootstrap(), protocol) {
                 @Override
                 protected void addSpecificHandlers(ChannelPipeline pipeline) {
-                    pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(1024, 2, 1, 2, 0));
+                    pipeline.addLast("frameDecoder", new UlbotechFrameDecoder());
                     pipeline.addLast("objectDecoder", new UlbotechProtocolDecoder(dataManager, protocol, properties));
                 }
             });
diff --git a/src/org/traccar/protocol/UlbotechFrameDecoder.java b/src/org/traccar/protocol/UlbotechFrameDecoder.java
new file mode 100644
index 000000000..3466118b0
--- /dev/null
+++ b/src/org/traccar/protocol/UlbotechFrameDecoder.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2014 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.buffer.ChannelBuffers;
+import org.jboss.netty.channel.Channel;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.jboss.netty.handler.codec.frame.FrameDecoder;
+import org.traccar.helper.ChannelBufferTools;
+
+public class UlbotechFrameDecoder extends FrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx,
+            Channel channel,
+            ChannelBuffer buf) throws Exception {
+        
+        if (buf.readableBytes() < 2) {
+            return null;
+        }
+
+        int index = buf.indexOf(buf.readerIndex() + 1, buf.writerIndex(), (byte) 0xF8);
+        if (index != -1) {
+            ChannelBuffer result = ChannelBuffers.buffer(index - buf.readerIndex());
+
+            while (buf.readerIndex() < index) {
+                int b = buf.readUnsignedByte();
+                if (b == 0xF7) {
+                    int ext = buf.readUnsignedByte();
+                    if (ext == 0x00) {
+                        result.writeByte(0xF7);
+                    } else if (ext == 0x0F) {
+                        result.writeByte(0xF8);
+                    }
+                } else {
+                    result.writeByte(b);
+                }
+            }
+
+            return result;
+        }
+
+        return null;
+    }
+
+}
-- 
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