From 10a11e03fbb45506973c85ae49d0fd1443d0f9f1 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Fri, 5 Nov 2021 16:48:27 -0700
Subject: Support new Xexun protocol (fix #4727)

---
 .../org/traccar/protocol/Xexun2FrameDecoder.java   | 69 ++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 src/main/java/org/traccar/protocol/Xexun2FrameDecoder.java

(limited to 'src/main/java/org/traccar/protocol/Xexun2FrameDecoder.java')

diff --git a/src/main/java/org/traccar/protocol/Xexun2FrameDecoder.java b/src/main/java/org/traccar/protocol/Xexun2FrameDecoder.java
new file mode 100644
index 000000000..521d0209c
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/Xexun2FrameDecoder.java
@@ -0,0 +1,69 @@
+/*
+ * 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.buffer.Unpooled;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandlerContext;
+import org.traccar.BaseFrameDecoder;
+import org.traccar.helper.BufferUtil;
+
+public class Xexun2FrameDecoder extends BaseFrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        if (buf.readableBytes() < 5) {
+            return null;
+        }
+
+        ByteBuf flag = Unpooled.wrappedBuffer(new byte[] {(byte) 0xfa, (byte) 0xaf});
+        int index;
+        try {
+            index = BufferUtil.indexOf(flag, buf, buf.readerIndex() + 2, buf.writerIndex());
+        } finally {
+            flag.release();
+        }
+
+        if (index >= 0) {
+            ByteBuf result = Unpooled.buffer(index + 2 - buf.readerIndex());
+
+            while (buf.readerIndex() < index + 2) {
+                int b = buf.readUnsignedByte();
+                if (b == 0xfb && buf.isReadable() && buf.getUnsignedByte(buf.readerIndex()) == 0xbf) {
+                    buf.readUnsignedByte(); // skip
+                    int ext = buf.readUnsignedByte();
+                    if (ext == 0x01) {
+                        result.writeByte(0xfa);
+                        result.writeByte(0xaf);
+                    } else if (ext == 0x02) {
+                        result.writeByte(0xfb);
+                        result.writeByte(0xbf);
+                    }
+                } else {
+                    result.writeByte(b);
+                }
+            }
+
+            return result;
+        }
+
+        return null;
+    }
+
+}
-- 
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