From b595ec1bede3e30447b49bb7340f88c9b3a3f97f Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Sat, 13 Apr 2019 22:25:50 -0700
Subject: Support ITS binary checksum

---
 .../java/org/traccar/protocol/ItsFrameDecoder.java | 48 ++++++++++++++++++++++
 .../java/org/traccar/protocol/ItsProtocol.java     |  3 +-
 2 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/org/traccar/protocol/ItsFrameDecoder.java

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

diff --git a/src/main/java/org/traccar/protocol/ItsFrameDecoder.java b/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
new file mode 100644
index 000000000..79b341760
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
@@ -0,0 +1,48 @@
+/*
+ * 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.channel.Channel;
+import io.netty.channel.ChannelHandlerContext;
+import org.traccar.BaseFrameDecoder;
+
+public class ItsFrameDecoder extends BaseFrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        int delimiterIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*');
+
+        if (buf.writerIndex() > delimiterIndex + 1 && buf.getByte(delimiterIndex + 1) == '*') {
+            delimiterIndex += 1;
+        }
+
+        ByteBuf frame;
+        if (buf.getByte(delimiterIndex - 2) == ',') {
+            frame = buf.readRetainedSlice(delimiterIndex - 1 - buf.readerIndex());
+            buf.skipBytes(1); // binary checksum
+        } else {
+            frame = buf.readRetainedSlice(delimiterIndex - buf.readerIndex());
+        }
+
+        buf.skipBytes(1); // delimiter
+
+        return frame;
+    }
+
+}
diff --git a/src/main/java/org/traccar/protocol/ItsProtocol.java b/src/main/java/org/traccar/protocol/ItsProtocol.java
index f53600dc9..e074f9277 100644
--- a/src/main/java/org/traccar/protocol/ItsProtocol.java
+++ b/src/main/java/org/traccar/protocol/ItsProtocol.java
@@ -18,7 +18,6 @@ package org.traccar.protocol;
 import io.netty.handler.codec.string.StringDecoder;
 import io.netty.handler.codec.string.StringEncoder;
 import org.traccar.BaseProtocol;
-import org.traccar.CharacterDelimiterFrameDecoder;
 import org.traccar.PipelineBuilder;
 import org.traccar.TrackerServer;
 
@@ -28,7 +27,7 @@ public class ItsProtocol extends BaseProtocol {
         addServer(new TrackerServer(false, getName()) {
             @Override
             protected void addProtocolHandlers(PipelineBuilder pipeline) {
-                pipeline.addLast(new CharacterDelimiterFrameDecoder(1024, '*'));
+                pipeline.addLast(new ItsFrameDecoder());
                 pipeline.addLast(new StringEncoder());
                 pipeline.addLast(new StringDecoder());
                 pipeline.addLast(new ItsProtocolDecoder(ItsProtocol.this));
-- 
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