org.eclipse.neoscada.protocol.iec60870.apci.APDUEncoder.java Source code

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Here is the source code for org.eclipse.neoscada.protocol.iec60870.apci.APDUEncoder.java

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/*******************************************************************************
 * Copyright (c) 2014 IBH SYSTEMS GmbH and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBH SYSTEMS GmbH - initial API and implementation
 *******************************************************************************/
package org.eclipse.neoscada.protocol.iec60870.apci;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.EncoderException;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.ReferenceCountUtil;

import java.nio.ByteOrder;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class APDUEncoder extends MessageToByteEncoder<APCIBase> {
    private final static Logger logger = LoggerFactory.getLogger(APDUEncoder.class);

    public APDUEncoder() {
        super(APCIBase.class);
    }

    @Override
    protected void encode(final ChannelHandlerContext ctx, final APCIBase msg, final ByteBuf out) throws Exception {
        logger.trace("encode - ctx: {}, msg: {}", ctx, msg);

        if (msg instanceof UnnumberedControl) {
            handleUFormat((UnnumberedControl) msg, out);
        } else if (msg instanceof Supervisory) {
            handleSFormat((Supervisory) msg, out);
        } else if (msg instanceof InformationTransfer) {
            handleIFormat((InformationTransfer) msg, out);
        }
    }

    private void handleIFormat(final InformationTransfer msg, ByteBuf out) {
        final ByteBuf data = msg.getData();
        try {
            out = out.order(ByteOrder.LITTLE_ENDIAN);

            final int len = data.readableBytes();

            if (len > Constants.APCI_MAX_DATA_LENGTH) {
                throw new EncoderException(String.format("Packet too big - %s bytes", len));
            }

            out.ensureWritable(6 + len);
            out.writeByte(Constants.START_BYTE);
            out.writeByte(4 + len);
            out.writeShort(msg.getSendSequenceNumber() << 1);
            out.writeShort(msg.getReceiveSequenceNumber() << 1);
            out.writeBytes(data);
        } finally {
            ReferenceCountUtil.release(msg.getData());
        }
    }

    private void handleSFormat(final Supervisory msg, ByteBuf out) {
        out = out.order(ByteOrder.LITTLE_ENDIAN);

        out.ensureWritable(6);
        out.writeByte(Constants.START_BYTE);
        out.writeByte(4);
        out.writeBytes(new byte[] { 0x01, 0x00 });
        out.writeShort(msg.getReceiveSequenceNumber() << 1);
    }

    private void handleUFormat(final UnnumberedControl msg, final ByteBuf out) {
        out.ensureWritable(6);
        out.writeByte(Constants.START_BYTE);
        out.writeByte(4);
        out.writeByte(msg.getFunction().getNumericValue() | 0x03 /* bits 1 and 2*/);
        out.writeZero(3);
    }
}