From 511520f9ac393735ec2c9fc5a18b2d4be8d071c5 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Sat, 30 Nov 2019 12:22:58 -0800
Subject: Implement Omnicomm protocol

---
 .../org/traccar/protocol/OmnicommFrameDecoder.java | 57 ++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 src/main/java/org/traccar/protocol/OmnicommFrameDecoder.java

(limited to 'src/main/java/org/traccar/protocol/OmnicommFrameDecoder.java')

diff --git a/src/main/java/org/traccar/protocol/OmnicommFrameDecoder.java b/src/main/java/org/traccar/protocol/OmnicommFrameDecoder.java
new file mode 100644
index 000000000..d6fedc40e
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/OmnicommFrameDecoder.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2019 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.buffer.Unpooled;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandlerContext;
+import org.traccar.BaseFrameDecoder;
+
+public class OmnicommFrameDecoder extends BaseFrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        if (buf.readableBytes() < 10) {
+            return null;
+        }
+
+        int endIndex = buf.getUnsignedShortLE(2) + buf.readerIndex() + 5;
+        if (buf.writerIndex() < endIndex) {
+            return null;
+        }
+
+        ByteBuf result = Unpooled.buffer();
+        result.writeByte(buf.readUnsignedByte());
+        while (buf.readerIndex() <= endIndex) {
+            int b = buf.readUnsignedByte();
+            if (b == 0xDB) {
+                int ext = buf.readUnsignedByte();
+                if (ext == 0xDC) {
+                    result.writeByte(0xC0);
+                } else if (ext == 0xDD) {
+                    result.writeByte(0xDB);
+                }
+            } else {
+                result.writeByte(b);
+            }
+        }
+        return  result;
+    }
+
+}
-- 
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