Add custom frame decoder

1 files changed, 75 insertions, 0 deletions

diff --git a/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java b/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java
new file mode 100644
index 000000000..0fb82528b
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java
@@ -0,0 +1,75 @@
+/*
+ * 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;
+import org.traccar.BasePipelineFactory;
+
+import java.nio.charset.StandardCharsets;
+import java.util.BitSet;
+
+public class NavtelecomFrameDecoder extends BaseFrameDecoder {
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
+
+        if (buf.getByte(buf.readerIndex()) == '@') {
+
+            int length = buf.getUnsignedShortLE(12) + 12 + 2 + 2;
+            if (buf.readableBytes() >= length) {
+                return buf.readRetainedSlice(length);
+            }
+
+        } else {
+
+            NavtelecomProtocolDecoder protocolDecoder =
+                    BasePipelineFactory.getHandler(ctx.pipeline(), NavtelecomProtocolDecoder.class);
+            if (protocolDecoder == null) {
+                throw new RuntimeException("Decoder not found");
+            }
+
+            String type = buf.getCharSequence(buf.readerIndex(), 2, StandardCharsets.US_ASCII).toString();
+            BitSet bits = protocolDecoder.getBits();
+
+            if (type.equals("~A")) {
+                int count = buf.getUnsignedByte(buf.readerIndex() + 2);
+                int length = 2 + 1 + 1;
+
+                for (int i = 0; i < count; i++) {
+                    for (int j = 0; j < bits.length(); j++) {
+                        if (bits.get(j)) {
+                            length += NavtelecomProtocolDecoder.getItemLength(j + 1);
+                        }
+                    }
+                }
+
+                if (buf.readableBytes() >= length) {
+                    return buf.readRetainedSlice(length);
+                }
+            } else {
+                throw new UnsupportedOperationException("Unsupported message type: " + type);
+            }
+
+        }
+
+        return null;
+    }
+
+}