Optimized IP to ISO3166 Country Code Mapping in C#

/*
 * GameWatch - Server Browser for online games
 * Copyright (C) 2003 Rodrigo Reyes <reyes@charabia.net>
 *
 * 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 of the
 * License, 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 */
using System;
using System.IO;

namespace GameWatch.Utils.Net
{
    public class IPToCountry
    {
	private BitVectorTrie m_trie = new BitVectorTrie();
	public static int NetworkCodeCount = 0;

	public void Load(string filename)
	{
	    StreamReader nccin = new StreamReader(filename);
	    Load(nccin);
	}

	public void Load(StreamReader nccin)
	{
	    try {
		string line;
		char[] seps = new char[] { '|' };
		while ( (line = nccin.ReadLine()) != null)
		    {
			string[] data = line.Split(seps);
			
			// Make the following assumption:
			// if 2nd entry is 2 chars, it's a country code.
			// if there is not dot in 4th entry, it's an IP (not an ASN)
			if ((data.Length > 2) && (data[1].Length == 2) && (data[3].IndexOf('.')>=0))
			    {
				//				Console.WriteLine("{0} -> {1}", data[3], data[1]);
				AddIp(data[3], data[1]);
				NetworkCodeCount++;
			    }
		    }
	    } catch (Exception exc)
		{
		    Console.WriteLine("exc: {0}", exc);
		}
	    finally
		{
		    nccin.Close();
		}
 
	}

	public string GetCountry(string ip)
	{
	    BitVector key = IpToBitVector(ip);
	    return (string)m_trie.GetBest(key);
	}

	private void AddIp(string ip, string country)
	{
	    BitVector key = IpToBitVector(ip);
	    m_trie.Add(key, String.Intern(country.ToUpper()));
	}

	private BitVector IpToBitVector(string ip)
	{
	    string[] elements = ip.Split('.');
	    BitVector bv = new BitVector();
	    foreach(string e in elements)
		{
		    int i = Int32.Parse(e);
		    bv.AddData(i, 8);
		}
	    return bv;
	}

	static public void Test()
	{
	    IPToCountry itc = new IPToCountry();
	    itc.Load(@"resources/ripencc.latest");
	    itc.Load(@"resources/arin.20010316");
	    itc.Load(@"resources/apnic-2001-05-01");
	    itc.Load(@"resources/lacnic.20030101");

	    //	    itc.Test();
	    Console.WriteLine("217.224.0.0 = {0}", itc.GetCountry("217.224.0.0"));
	    Console.WriteLine("217.224.133.25 = {0}", itc.GetCountry("217.224.133.25"));

	    Console.WriteLine("217.208.23.45 = {0} (SE)", itc.GetCountry("217.208.23.45"));
	    Console.WriteLine("195.96.96.111 = {0} (NL)", itc.GetCountry("195.96.96.111"));
	    Console.WriteLine("81.16.128.23 = {0} (RU)", itc.GetCountry("81.16.128.23"));
	    Console.WriteLine("62.4.160.87 = {0} (BE)", itc.GetCountry("62.4.160.87"));
	    Console.WriteLine("81.50.140.32 = {0} (ICI)", itc.GetCountry("81.50.140.32"));
	    Console.WriteLine("81.70.12.45 = {0} (NL))", itc.GetCountry("81.70.12.45"));
	    Console.WriteLine("81.88.95.45 = {0} (KZ))", itc.GetCountry("81.88.95.45"));

	    for (int i=0; i<255; i++)
		{
		    string ip = "217.170." + i + ".234";
		    Console.WriteLine("{0} = {1}", ip, itc.GetCountry(ip));
		}
	}

    }
}