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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.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import org.traccar.BaseFrameDecoder;
public class OmnicommFrameDecoder extends BaseFrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
if (buf.readableBytes() < 6) {
return null;
}
int endIndex = buf.getUnsignedShortLE(buf.readerIndex() + 2) + buf.readerIndex() + 6;
if (buf.writerIndex() < endIndex) {
return null;
}
ByteBuf result = Unpooled.buffer();
result.writeByte(buf.readUnsignedByte());
while (buf.readerIndex() < endIndex) {
int b = buf.readUnsignedByte();
if (b == 0xDB) {
int ext = buf.readUnsignedByte();
if (ext == 0xDC) {
result.writeByte(0xC0);
} else if (ext == 0xDD) {
result.writeByte(0xDB);
}
endIndex += 1;
} else {
result.writeByte(b);
}
}
return result;
}
}
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