001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *  
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *  
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License. 
018 *  
019 */
020
021package org.apache.directory.server.ntp.io;
022
023
024import java.nio.ByteBuffer;
025
026import org.apache.directory.server.ntp.messages.LeapIndicatorType;
027import org.apache.directory.server.ntp.messages.ModeType;
028import org.apache.directory.server.ntp.messages.NtpMessage;
029import org.apache.directory.server.ntp.messages.ReferenceIdentifier;
030
031
032/**
033 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
034 */
035public class NtpMessageEncoder
036{
037    /**
038     * Encodes the {@link NtpMessage} into the {@link ByteBuffer}.
039     *
040     * @param byteBuffer
041     * @param message
042     */
043    public void encode( ByteBuffer byteBuffer, NtpMessage message )
044    {
045        byte header = 0x00;
046        header = encodeLeapIndicator( message.getLeapIndicator(), header );
047        header = encodeVersionNumber( message.getVersionNumber(), header );
048        header = encodeMode( message.getMode(), header );
049        byteBuffer.put( header );
050
051        byteBuffer.put( ( byte ) ( message.getStratum().getOrdinal() & 0xFF ) );
052        byteBuffer.put( ( byte ) ( message.getPollInterval() & 0xFF ) );
053        byteBuffer.put( ( byte ) ( message.getPrecision() & 0xFF ) );
054
055        byteBuffer.putInt( message.getRootDelay() );
056        byteBuffer.putInt( message.getRootDispersion() );
057
058        encodeReferenceIdentifier( message.getReferenceIdentifier(), byteBuffer );
059
060        message.getReferenceTimestamp().writeTo( byteBuffer );
061        message.getOriginateTimestamp().writeTo( byteBuffer );
062        message.getReceiveTimestamp().writeTo( byteBuffer );
063        message.getTransmitTimestamp().writeTo( byteBuffer );
064    }
065
066
067    private byte encodeLeapIndicator( LeapIndicatorType leapIndicator, byte header )
068    {
069        byte twoBits = ( byte ) ( leapIndicator.getOrdinal() & 0x03 );
070        return ( byte ) ( ( twoBits << 6 ) | header );
071    }
072
073
074    private byte encodeVersionNumber( int versionNumber, byte header )
075    {
076        byte threeBits = ( byte ) ( versionNumber & 0x07 );
077        return ( byte ) ( ( threeBits << 3 ) | header );
078    }
079
080
081    private byte encodeMode( ModeType mode, byte header )
082    {
083        byte threeBits = ( byte ) ( mode.getOrdinal() & 0x07 );
084        return ( byte ) ( threeBits | header );
085    }
086
087
088    private void encodeReferenceIdentifier( ReferenceIdentifier identifier, ByteBuffer byteBuffer )
089    {
090        char[] characters = identifier.getCode().toCharArray();
091
092        for ( int ii = 0; ii < characters.length; ii++ )
093        {
094            byteBuffer.put( ( byte ) characters[ii] );
095        }
096    }
097}