/*
 * Created on Jun 11, 2009
 * Created by Paul Gardner
 * 
 * Copyright 2009 Vuze, Inc.  All rights reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License only.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */


package com.aelitis.azureus.core.util;

import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;

import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

public class 
DNSUtils 
{
	private static String
	getFactory()
	{
		return( System.getProperty( "azureus.dns.context.factory", "com.sun.jndi.dns.DnsContextFactory" ));
	}
	
	public static DirContext
	getInitialDirContext()
	
		throws NamingException
	{
		Hashtable env = new Hashtable();
		
		env.put ("java.naming.factory.initial", getFactory());
		
		return( new InitialDirContext( env ));

	}
	
	public static Inet6Address
	getIPV6ByName(
		String		host )
	
		throws UnknownHostException
	{
		List<Inet6Address>	all = getAllIPV6ByName( host );
	
		return( all.get(0));
	}
	
	public static List<Inet6Address>
	getAllIPV6ByName(
		String		host )
		
		throws UnknownHostException
	{
		List<Inet6Address>	result = new ArrayList<Inet6Address>();

		try{			
			DirContext context = getInitialDirContext();
			
			Attributes attrs = context.getAttributes( host, new String[]{ "AAAA" });
			
			if ( attrs != null ){
			
				Attribute attr = attrs.get( "aaaa" );
			
				if ( attr != null ){
					
					NamingEnumeration values = attr.getAll();
			
					while( values.hasMore()){
					
						Object value = values.next();
						
						if ( value instanceof String ){
							
							try{
								result.add( (Inet6Address)InetAddress.getByName((String)value));
								
							}catch( Throwable e ){
							}
						}
					}
				}
			}
		}catch( Throwable e ){
		}
		
		if ( result.size() > 0 ){
		
			return( result );
		}
		
		throw( new UnknownHostException( host ));
	}
}