1 files changed, 49 insertions, 0 deletions
diff --git a/src/main/java/org/traccar/protocol/DualcamFrameDecoder.java b/src/main/java/org/traccar/protocol/DualcamFrameDecoder.java
new file mode 100644
index 000000000..312d43f19
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/DualcamFrameDecoder.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2021 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 DualcamFrameDecoder extends BaseFrameDecoder {
+
+    private static final int MESSAGE_MINIMUM_LENGTH = 4;
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        if (buf.readableBytes() < MESSAGE_MINIMUM_LENGTH) {
+            return null;
+        }
+
+        int length;
+        if (buf.getUnsignedShort(buf.readerIndex()) == 0) {
+            length = 16;
+        } else {
+            length = 4 + buf.getUnsignedShort(buf.readerIndex() + 2);
+        }
+
+        if (buf.readableBytes() >= length) {
+            return buf.readRetainedSlice(length);
+        }
+
+        return null;
+    }
+
+}