Реализация стандартного шлюза DHCP

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Socket;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Pattern;
 
import org.apache.xml.serializer.ToXMLStream;
import org.xml.sax.SAXException;
 
import ru.bitel.bgbilling.common.DefaultSetup;
import bitel.billing.common.module.ipn.IPNContractStatus;
import bitel.billing.server.ipn.bean.Gate;
import bitel.billing.server.ipn.dlink.UserPortStatus;
import bitel.billing.server.ipn.dlink.UserPortStatus.UserPortStatusParser;
import bitel.billing.server.util.Utils;
import bitel.billing.server.ipn.GateWorker;
 
   void parentSync( Gate child, GateWorker childWorker )
    {
        Pattern patternTab = Pattern.compile( "\\t" );
		log.debug( "parentSync" );
 
        String host = gate.getHost();
        int port = gate.getPort();
        int gid = gate.getId();
 
        if( Utils.isEmptyString( host ) || port <= 0 )
        {
            log.error( "Can't get IP/port for BGDHCP for this gate! " );
            gateErrors.append( "Не указан адрес сервера dhcp для данного шлюза!" );
            return;
        }
 
        if( log.isDebugEnabled() )
            log.debug( gid + " gate: " + host + ":" + port );
 
 
        Socket socket = null;
        try
        {
            //if( childWorker instanceof UserPortStatusParser )
            //{
                //List userPortStatusList = childWorker.getUserList( childWorker.statusList );
				List userPortStatusList = childWorker.getUserList( statusList );
 
                socket = new Socket( host, port );
                InputStreamReader isr = new InputStreamReader( socket.getInputStream() );
                BufferedReader in = new BufferedReader( isr );
 
                ToXMLStream stream = new ToXMLStream();
                stream.setOutputStream(  socket.getOutputStream() );
 
                stream.setEncoding( "UTF-8" );
                stream.startDocument();
 
                stream.startElement( "sync" );
                stream.addAttribute( "type", "dhcp" );
 
                Gate gate = child;
                syncGate( gate, stream );
 
                stream.startElement( "list" );
                stream.addAttribute( "gateId", String.valueOf( gate.getId() ) );
                stream.endElement( "list" );
                stream.flushPending();
                stream.getWriter().flush();
 
                Map portStatusMap = new HashMap();
                String line = in.readLine();
 
                while( line != null && !"".equals( line ) )
                {
                    String[] p = patternTab.split( line );
                    if( p.length > 1 )
                    {
                        UserPortStatus st = new UserPortStatus();
                        st.ipAddr = p[1];
                        st.port = Utils.parseIntString( p[0], -1 );
                        portStatusMap.put( st.port, st );
                    }
 
                    line = in.readLine();
                }
 
                String gateId = String.valueOf( gate.getId() );
 
                for( UserPortStatus status : userPortStatusList )
                {
                    UserPortStatus s = portStatusMap.remove( status.port );
 
 
 
                    if(  (s == null || !s.ipAddr.equals( status.ipAddr ) ) && 
                    	status.status.status != IPNContractStatus.STATUS_REMOVED )
                    {
                    	if ( status.macAddr == null)
                    	{
	                    	stream.startElement( "port" );
	                        stream.addAttribute( "gateId", gateId );
	                        stream.addAttribute( "id", String.valueOf( status.port ) );
	                        stream.addAttribute( "ip", status.ipAddr );	                        
	                        stream.endElement( "port" );
                    	}
                    	else
                    	{
	                        stream.startElement( "portMac" );
	                        stream.addAttribute( "gateId", gateId );
	                        stream.addAttribute( "id", String.valueOf( status.port ) );
	                        stream.addAttribute( "ip", status.ipAddr );
	                        stream.addAttribute( "mac", status.macAddr );
	                        stream.endElement( "portMac" );	                    		
                    	}
 
                    }
 
 
                    //удаляем в одном месте
 
                    if( s != null && status.status.status == IPNContractStatus.STATUS_REMOVED )
                    {
                        stream.startElement( "removePort" );
                        stream.addAttribute( "gateId", gateId );
                        stream.addAttribute( "id", String.valueOf( status.port ) );
                        stream.addAttribute( "ip", status.ipAddr );
                        stream.endElement( "removePort" );
                    }
 
 
 
                }
 
                stream.flushPending();
                stream.getWriter().flush();
 
                stream.endElement( "sync" );
                stream.endDocument();
                stream.getWriter().flush();
            //}
        }
 
        finally
        {
            if( socket != null )
            {
                try 
                {
                    socket.close();
                } 
                catch (Exception e) 
                {}
            }
        }
    }
 
    protected void syncGates( Gate gate, ToXMLStream stream )
    {
        try
        {
            if( gate != null )
            {
                stream.startElement( "gate" );
                stream.addAttribute( "id", String.valueOf( gate.getId() ) );
                stream.addAttribute( "host", gate.getHost() );
                DefaultSetup gateSetup = new DefaultSetup( gate.getConfig(), "\n" );
                Map params = gateSetup.getHashValuesWithPrefix( "dhcp." );
                for( Entry e : params.entrySet() )
                {
                    stream.startElement( "param" );
                    stream.addAttribute( "id", "dhcp." + e.getKey() );
                    stream.addAttribute( "value", e.getValue() );
                    stream.endElement( "param" );
                }
 
                if( gate.getChildren() != null )
                    for( Gate g : gate.getChildren() )
                    {
                        syncGates( g, stream );
                    }
 
                stream.endElement( "gate" );
            }
        }
        catch( SAXException e )
        {
            e.printStackTrace();
        }
    }
 
    protected void syncGate( Gate gate, ToXMLStream stream )
    {
        try
        {
            if( gate != null )
            {
                List gateList = new ArrayList();
                gateList.add( gate );
                Gate g = gate;
                while( g != null )
                {
                    gateList.add( g );
                    g = g.getParent();
                }
 
                HashMap params = new HashMap();
                for( int i = gateList.size() - 1; i >= 0; i-- )
                {
                    DefaultSetup gateSetup = new DefaultSetup( gateList.get( i ).getConfig(), "\n" );
                    Map p = gateSetup.getHashValuesWithPrefix( "dhcp." );
                    for( Entry e : p.entrySet() )
                    {
                        params.put( e.getKey(), e.getValue() );
                    }
                }
 
                stream.startElement( "gate" );
                stream.addAttribute( "id", String.valueOf( gate.getId() ) );
                stream.addAttribute( "host", gate.getHost() );
 
                for( Entry e : params.entrySet() )
                {
                    stream.startElement( "param" );
                    stream.addAttribute( "id", "dhcp." + e.getKey() );
                    stream.addAttribute( "value", e.getValue() );
                    stream.endElement( "param" );
                }
 
                stream.endElement( "gate" );
            }
        }
        catch( SAXException e )
        {
            e.printStackTrace();
        }
    }
 
    protected List getGateListFromTree( Gate root )
    {
        List result = new ArrayList();
        getGateListFromTree( result, root );
        return result;
    }
 
    protected void getGateListFromTree( List list, Gate root )
    {
        if( root != null )
            list.add( root );
 
        if( root.getChildren() != null )
            for( Gate gate : root.getChildren() )
            {
                getGateListFromTree( list, gate );
            }
    }