1 files changed, 67 insertions, 0 deletions
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..cebfdca5f
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
@@ -0,0 +1,67 @@
+/*
+ * 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;
+import org.traccar.helper.BufferUtil;
+
+public class ItsFrameDecoder extends BaseFrameDecoder {
+
+    private static final int MINIMUM_LENGTH = 20;
+
+    private ByteBuf readFrame(ByteBuf buf, int delimiterIndex, int skip) {
+        int headerIndex = buf.indexOf(buf.readerIndex() + 1, buf.writerIndex(), (byte) '$');
+        if (headerIndex > 0 && headerIndex < delimiterIndex) {
+            return buf.readRetainedSlice(headerIndex - buf.readerIndex());
+        } else {
+            ByteBuf frame = buf.readRetainedSlice(delimiterIndex - buf.readerIndex());
+            buf.skipBytes(skip);
+            return frame;
+        }
+    }
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        while (buf.isReadable() && buf.getByte(buf.readerIndex()) != '$') {
+            buf.skipBytes(1);
+        }
+
+        int delimiterIndex = BufferUtil.indexOf("\r\n", buf);
+        if (delimiterIndex > MINIMUM_LENGTH) {
+            return readFrame(buf, delimiterIndex, 2);
+        } else {
+            delimiterIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*');
+            if (delimiterIndex > MINIMUM_LENGTH) {
+                if (buf.writerIndex() > delimiterIndex + 1 && buf.getByte(delimiterIndex + 1) == '*') {
+                    delimiterIndex += 1;
+                }
+                if (buf.getByte(delimiterIndex - 2) == ',') {
+                    return readFrame(buf, delimiterIndex - 1, 2); // skip binary checksum
+                } else {
+                    return readFrame(buf, delimiterIndex, 1);
+                }
+            }
+        }
+
+        return null;
+    }
+
+}