MacAddressResolver.java

/*
 *      Copyright (C) 2005-2009 Team XBMC
 *      http://xbmc.org
 *
 *  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; either version 2, or (at your option)
 *  any later version.
 *
 *  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 XBMC Remote; see the file license.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *  http://www.gnu.org/copyleft/gpl.html
 *
 */

package org.xbmc.android.util;

import java.io.BufferedReader;
import java.io.FileReader;
import java.net.InetAddress;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;

/**
 * Resolve IP addresses to corresponding MAC addresses if possible
 * 
 * @author Team XBMC
 */
public class MacAddressResolver implements Runnable{
	
	private String mHost = null;
	private String mMac = null;
	private Handler mHandler;
	
	public static final String MESSAGE_MAC_ADDRESS = "MAC_ADDRESS";
	
	public MacAddressResolver(String ipString, Handler handler){
		mHost = ipString;
		mHandler = handler;
	}
	
	public void run(){
		mMac = arpResolve(mHost);
		Bundle bundle = new Bundle();
		bundle.putString(MESSAGE_MAC_ADDRESS, mMac);
		Message message = new Message();
		message.setData(bundle);
		mHandler.sendMessage(message);
	}
	
	private String arpResolve(String host){
		System.out.println("ARPRESOLVE HOST: " + host);
		try{
			//Parse it as a proper InetAddress - it might be a hostname. We don't know yet.
			InetAddress inet = InetAddress.getByName(host);
			
			//initiate some sort of traffic to ensure we get an arp entry (if we're on same subnet, that is...)
			inet.isReachable(500); //timeout of 500ms. just to trigger the arp resolution process
			
			//Get the official string representation of the resolved ip address
			String ipString = inet.getHostAddress();
			BufferedReader br = new BufferedReader(new FileReader("/proc/net/arp"));
			String line = "";
			while(true){
				line = br.readLine();
				if (line == null)
					break;
				if(line.startsWith(ipString)){
					br.close();
					System.out.println("ARPRESOLVE MAC:\n" + line);
					return line.split("\\s+")[3]; // 4th word, separated by "whitespace"
				}
			}
			br.close();
			return "";
	
		}catch(Exception e){
			return "";
		}

	}

}