/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.directory.server.dhcp.io;
import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.Iterator;
import org.apache.directory.server.dhcp.messages.DhcpMessage;
import org.apache.directory.server.dhcp.messages.HardwareAddress;
import org.apache.directory.server.dhcp.options.DhcpOption;
import org.apache.directory.server.dhcp.options.OptionsField;
import org.apache.directory.server.dhcp.options.dhcp.DhcpMessageType;
import org.apache.directory.server.i18n.I18n;
/**
* @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
* @version $Rev: 902331 $, $Date: 2010-01-23 02:41:35 +0100 (Sam, 23 jan 2010) $
*/
public class DhcpMessageEncoder
{
/**
* Converts a DhcpMessage object into a byte buffer.
*
* @param byteBuffer ByteBuffer to put DhcpMessage into
* @param message DhcpMessage to encode into ByteBuffer
*/
public void encode( ByteBuffer byteBuffer, DhcpMessage message )
{
byteBuffer.put( message.getOp() );
HardwareAddress hardwareAddress = message.getHardwareAddress();
byteBuffer.put( ( byte ) ( null != hardwareAddress ? hardwareAddress.getType() : 0 ) );
byteBuffer.put( ( byte ) ( null != hardwareAddress ? hardwareAddress.getLength() : 0 ) );
byteBuffer.put( ( byte ) message.getHopCount() );
byteBuffer.putInt( message.getTransactionId() );
byteBuffer.putShort( ( short ) message.getSeconds() );
byteBuffer.putShort( message.getFlags() );
writeAddress( byteBuffer, message.getCurrentClientAddress() );
writeAddress( byteBuffer, message.getAssignedClientAddress() );
writeAddress( byteBuffer, message.getNextServerAddress() );
writeAddress( byteBuffer, message.getRelayAgentAddress() );
writeBytes( byteBuffer, ( null != hardwareAddress ? hardwareAddress.getAddress() : new byte[]
{} ), 16 );
writeString( byteBuffer, message.getServerHostname(), 64 );
writeString( byteBuffer, message.getBootFileName(), 128 );
OptionsField options = message.getOptions();
// update message type option (if set)
if ( null != message.getMessageType() )
options.add( new DhcpMessageType( message.getMessageType() ) );
encodeOptions( options, byteBuffer );
}
/**
* Write a zero-terminated string to a field of len bytes.
*
* @param byteBuffer
* @param serverHostname
* @param i
*/
private void writeString( ByteBuffer byteBuffer, String string, int len )
{
if ( null == string )
string = "";
try
{
byte sbytes[] = string.getBytes( "ASCII" );
// writeBytes will automatically zero-pad and thus terminate the
// string.
writeBytes( byteBuffer, sbytes, len );
}
catch ( UnsupportedEncodingException e )
{
// should not happen
throw new RuntimeException( I18n.err( I18n.ERR_635 ), e );
}
}
/**
* Write an InetAddress to the byte buffer.
*
* @param byteBuffer
* @param currentClientAddress
*/
private void writeAddress( ByteBuffer byteBuffer, InetAddress currentClientAddress )
{
if ( null == currentClientAddress )
{
byte emptyAddress[] =
{ 0, 0, 0, 0 };
byteBuffer.put( emptyAddress );
}
else
{
byte[] addressBytes = currentClientAddress.getAddress();
byteBuffer.put( addressBytes );
}
}
/**
* Write an array of bytes to the buffer. Write exactly len bytes,
* truncating if more than len, padding if less than len bytes are
* available.
*
* @param byteBuffer
* @param currentClientAddress
*/
private void writeBytes( ByteBuffer byteBuffer, byte bytes[], int len )
{
if ( null == bytes )
bytes = new byte[]
{};
byteBuffer.put( bytes, 0, Math.min(len, bytes.length) );
// pad as necessary
int remain = len - bytes.length;
while ( remain-- > 0 )
byteBuffer.put( ( byte ) 0 );
}
private static final byte[] VENDOR_MAGIC_COOKIE =
{ ( byte ) 99, ( byte ) 130, ( byte ) 83, ( byte ) 99 };
public void encodeOptions( OptionsField options, ByteBuffer message )
{
message.put( VENDOR_MAGIC_COOKIE );
for ( Iterator i = options.iterator(); i.hasNext(); )
{
DhcpOption option = ( DhcpOption ) i.next();
option.writeTo( message );
}
// add end option
message.put( ( byte ) 0xff );
}
}