Copyright (c) 2000, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.launching;


import java.io.IOException;
import java.net.ConnectException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Random;

Utility class to find a port to debug on.
@noinstantiate
This class is not intended to be instantiated by clients.
@noextend
This class is not intended to be subclassed by clients./**
 * Utility class to find a port to debug on.
 * @noinstantiate This class is not intended to be instantiated by clients.
 * @noextend This class is not intended to be subclassed by clients.
 */
public class SocketUtil {
	private static final Random fgRandom= new Random(System.currentTimeMillis());

	
Returns a free port number on the specified host within the given range,
or -1 if none found.
Params:
host – name or IP address of host on which to find a free port
searchFrom – the port number from which to start searching
searchTo – the port number at which to stop searching
Returns:
a free port in the specified range, or -1 of none found
Deprecated:
Use findFreePort() instead. It is possible that this
	 method can return a port that is already in use since the implementation does
  not bind to the given port to ensure that it is free./**
	 * Returns a free port number on the specified host within the given range,
	 * or -1 if none found.
	 *
	 * @param host name or IP address of host on which to find a free port
	 * @param searchFrom the port number from which to start searching
	 * @param searchTo the port number at which to stop searching
	 * @return a free port in the specified range, or -1 of none found
	 * @deprecated Use <code>findFreePort()</code> instead. It is possible that this
	 * 	 method can return a port that is already in use since the implementation does
	 *   not bind to the given port to ensure that it is free.
	 */
	@Deprecated
	public static int findUnusedLocalPort(String host, int searchFrom, int searchTo) {

		for (int i= 0; i < 10; i++) {
			int port= getRandomPort(searchFrom, searchTo);
			try (Socket s= new Socket(host, port)){
			} catch (ConnectException e) {
				return port;
			} catch (IOException e) {
			}
		}
		return -1;
	}

	private static int getRandomPort(int low, int high) {
		return (int)(fgRandom.nextFloat() * (high-low)) + low;
	}

	
Returns a free port number on localhost, or -1 if unable to find a free port.
Returns:
a free port number on localhost, or -1 if unable to find a free port
Since:
3.0/**
	 * Returns a free port number on localhost, or -1 if unable to find a free port.
	 *
	 * @return a free port number on localhost, or -1 if unable to find a free port
	 * @since 3.0
	 */
	public static int findFreePort() {
		try (ServerSocket socket = new ServerSocket(0)) {
			return socket.getLocalPort();
		} catch (IOException e) {
		}
		return -1;
	}
}