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/*
* Copyright 2013 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;
public class AplicomFrameDecoder extends BaseFrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
// Skip Alive message
while (buf.isReadable() && Character.isDigit(buf.getByte(buf.readerIndex()))) {
buf.readByte();
}
// Check minimum length
if (buf.readableBytes() < 11) {
return null;
}
// Read flags
int version = buf.getUnsignedByte(buf.readerIndex() + 1);
int offset = 1 + 1 + 3;
if ((version & 0x80) != 0) {
offset += 4;
}
// Get data length
int length = buf.getUnsignedShort(buf.readerIndex() + offset);
offset += 2;
if ((version & 0x40) != 0) {
offset += 3;
}
length += offset; // add header
// Return buffer
if (buf.readableBytes() >= length) {
return buf.readRetainedSlice(length);
}
return null;
}
}
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