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/*
* 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 java.nio.charset.StandardCharsets;
import org.traccar.BaseFrameDecoder;
import org.traccar.BasePipelineFactory;
public class NavisFrameDecoder extends BaseFrameDecoder {
private static final int NTCB_HEADER_LENGTH = 16;
private static final int NTCB_LENGTH_OFFSET = 12;
private static final int FLEX_HEADER_LENGTH = 2;
private int flexDataSize;
public void setFlexDataSize(int flexDataSize) {
this.flexDataSize = flexDataSize;
}
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
if (buf.getByte(buf.readerIndex()) == 0x7F) {
return buf.readRetainedSlice(1); // keep alive
}
if (ctx != null && flexDataSize == 0) {
NavisProtocolDecoder protocolDecoder =
BasePipelineFactory.getHandler(ctx.pipeline(), NavisProtocolDecoder.class);
if (protocolDecoder != null) {
flexDataSize = protocolDecoder.getFlexDataSize();
}
}
if (flexDataSize > 0) {
if (buf.readableBytes() > FLEX_HEADER_LENGTH) {
int length = 0;
String type = buf.toString(buf.readerIndex(), 2, StandardCharsets.US_ASCII);
switch (type) {
// FLEX 1.0
case "~A" -> length = flexDataSize * buf.getByte(buf.readerIndex() + FLEX_HEADER_LENGTH) + 1 + 1;
case "~T" -> length = flexDataSize + 4 + 1;
case "~C" -> length = flexDataSize + 1;
// FLEX 2.0 (Extra packages)
case "~E" -> {
length++;
for (int i = 0; i < buf.getByte(buf.readerIndex() + FLEX_HEADER_LENGTH); i++) {
if (buf.readableBytes() > FLEX_HEADER_LENGTH + length + 1) {
length += buf.getUnsignedShort(length + FLEX_HEADER_LENGTH) + 2;
} else {
return null;
}
}
length++;
}
case "~X" -> length = buf.getUnsignedShortLE(buf.readerIndex() + FLEX_HEADER_LENGTH) + 4 + 1;
default -> {
return null;
}
}
if (buf.readableBytes() >= FLEX_HEADER_LENGTH + length) {
return buf.readRetainedSlice(buf.readableBytes());
}
}
} else {
if (buf.readableBytes() < NTCB_HEADER_LENGTH) {
return null;
}
int length = NTCB_HEADER_LENGTH + buf.getUnsignedShortLE(buf.readerIndex() + NTCB_LENGTH_OFFSET);
if (buf.readableBytes() >= length) {
return buf.readRetainedSlice(length);
}
}
return null;
}
}
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