org.code_house.ebus.netty.codec.SlaveTelegramDecoder.java Source code

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Here is the source code for org.code_house.ebus.netty.codec.SlaveTelegramDecoder.java

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/*
 * (C) Copyright 2017 Code-House, ?ukasz Dywicki.
 *
 * 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.code_house.ebus.netty.codec;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelHandlerContext;
import org.code_house.ebus.api.Constants;
import org.code_house.ebus.netty.codec.struct.Confirmation;
import org.code_house.ebus.netty.codec.struct.Rejection;
import org.code_house.ebus.netty.codec.struct.SlaveData;
import org.code_house.ebus.netty.codec.struct.SlaveHeader;

import java.nio.ByteBuffer;
import java.util.List;

public class SlaveTelegramDecoder extends EBusTelegramDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        if (in.readableBytes() == 0) {
            return;
        }

        int index = in.readerIndex();
        // no master, no slave, no broadcast -> slave reply or ACK
        if (in.readableBytes() >= 3) {
            // we have at least three bytes which should be slave ACK, slave reply len, slave crc.
            byte ack = in.readByte();
            if (ack == Constants.ACK) { // slave confirmed received data
                byte length = in.readByte();
                if (in.readableBytes() >= length + 1 /* crc */) {
                    ByteBuffer exchange = ByteBuffer.allocate(length);
                    in.getBytes(in.readerIndex(), exchange);
                    in.skipBytes(length);
                    byte crc = in.readByte();
                    SlaveData data = new SlaveData(exchange, calculateCrc(length), crc);
                    if (data.isValid()) {
                        // proper slave reply
                        out.add(new Confirmation());
                        out.add(new SlaveHeader(length));
                        out.add(data);
                    } else {
                        System.out.println("Slave CRC fail!!!");
                        in.discardReadBytes();
                    }
                }
            } else if (ack == Constants.NACK) {
                out.add(new Rejection());
            }
        }

        if (out.isEmpty()) {
            System.out.println("slave fail -> \n" + ByteBufUtil.prettyHexDump(in));
            in.readerIndex(index);
        }

        if (in.readableBytes() > 0) {
            out.add(in.readBytes(super.actualReadableBytes()));
        }
    }

}