/*
  * Copyright (c) 2002-2004 Mainsoft Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  */

using System;

using java.net;

namespace System.Data.Common
{
	public class DbPortResolver
	{
		public static int getMSSqlPort(String sqlName, String instanceName,int timeout)
		{
			int port = -1;
			try
			{
				DatagramSocket socket = new DatagramSocket();

				// send request
				sbyte[] buf = new sbyte[] {2};
				InetAddress address = InetAddress.getByName(sqlName);
				DatagramPacket packet = new DatagramPacket(buf, buf.Length, address, 1434);
				socket.send(packet);
				sbyte[] recbuf = new sbyte[1024];
				packet = new DatagramPacket(recbuf, recbuf.Length, packet.getAddress(), packet.getPort());

				// try to receive from socket while increasing timeouts in geometric progression
				int iterationTimeout = 1;
				int totalTimeout = 0;
				while (totalTimeout < timeout*1000)
				{
					socket.setSoTimeout(iterationTimeout);
					try
					{
						socket.receive(packet);
						break;
					}
					catch (SocketTimeoutException e)
					{
						totalTimeout += iterationTimeout;
						iterationTimeout *= 2;
					}
				}
				sbyte[] rcvdSbytes = packet.getData();
				char[] rcvdChars = new char[rcvdSbytes.Length];
				for(int i=0; i < rcvdSbytes.Length; i++)
				{
					rcvdChars[i] = (char)rcvdSbytes[i];
				}
				String received = new String(rcvdChars);

				java.util.StringTokenizer st = new java.util.StringTokenizer(received, ";");
				String prev = "";
				bool instanceReached = false;
				while (st.hasMoreTokens())
				{
					if (!instanceReached)
					{
						if (prev.Trim().Equals("InstanceName"))
						{
							if (String.Compare(instanceName,st.nextToken().Trim(),true) == 0)
							{
								instanceReached = true;
							}
						}
					}
					else
					{
						if (prev.Trim().Equals("tcp"))
						{
							port = java.lang.Integer.parseInt(st.nextToken().Trim());
							break;
						}
					}
					prev = st.nextToken();
				}
				socket.close();
				return port;

			}
			catch (java.lang.Exception e)
			{
				return port;
			}
		}
	    
	}
}