1 files changed, 56 insertions, 0 deletions
diff --git a/src/main/java/org/traccar/protocol/Gt06FrameDecoder.java b/src/main/java/org/traccar/protocol/Gt06FrameDecoder.java
new file mode 100644
index 000000000..cc934be42
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/Gt06FrameDecoder.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2014 - 2018 Anton Tananaev (anton@traccar.org)
+ *
+ * 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 io.netty.buffer.ByteBuf;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandlerContext;
+import org.traccar.BaseFrameDecoder;
+
+public class Gt06FrameDecoder extends BaseFrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        if (buf.readableBytes() < 5) {
+            return null;
+        }
+
+        int length = 2 + 2; // head and tail
+
+        if (buf.getByte(buf.readerIndex()) == 0x78) {
+            length += 1 + buf.getUnsignedByte(buf.readerIndex() + 2);
+        } else {
+            length += 2 + buf.getUnsignedShort(buf.readerIndex() + 2);
+        }
+
+        if (buf.readableBytes() >= length && buf.getUnsignedShort(buf.readerIndex() + length - 2) == 0x0d0a) {
+            return buf.readRetainedSlice(length);
+        }
+
+        int endIndex = buf.readerIndex() - 1;
+        do {
+            endIndex = buf.indexOf(endIndex + 1, buf.writerIndex(), (byte) 0x0d);
+            if (endIndex > 0 && buf.writerIndex() > endIndex + 1 && buf.getByte(endIndex + 1) == 0x0a) {
+                return buf.readRetainedSlice(endIndex + 2 - buf.readerIndex());
+            }
+        } while (endIndex > 0);
+
+        return null;
+    }
+
+}