zeppelin-interpreter/src/main/java/org/apache/zeppelin/interpreter/remote/RemoteInterpreterUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.zeppelin.interpreter.remote;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.ConnectException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;

/**
 *
 */
public class RemoteInterpreterUtils {
  static Logger LOGGER = LoggerFactory.getLogger(RemoteInterpreterUtils.class);
  public static int findRandomAvailablePortOnAllLocalInterfaces() throws IOException {
    int port;
    try (ServerSocket socket = new ServerSocket(0);) {
      port = socket.getLocalPort();
      socket.close();
    }
    return port;
  }

  /**
   * start:end
   *
   * @param portRange
   * @return
   * @throws IOException
   */
  public static int findRandomAvailablePortOnAllLocalInterfaces(String portRange)
      throws IOException {

    // ':' is the default value which means no constraints on the portRange
    if (StringUtils.isBlank(portRange) || portRange.equals(":")) {
      int port;
      try (ServerSocket socket = new ServerSocket(0);) {
        port = socket.getLocalPort();
        socket.close();
      }
      return port;
    }
    // valid user registered port https://en.wikipedia.org/wiki/Registered_port
    int start = 1024;
    int end = 65535;
    String[] ports = portRange.split(":", -1);
    if (!ports[0].isEmpty()) {
      start = Integer.parseInt(ports[0]);
    }
    if (!ports[1].isEmpty()) {
      end = Integer.parseInt(ports[1]);
    }
    for (int i = start; i <= end; ++i) {
      try {
        ServerSocket socket = new ServerSocket(i);
        socket.close();
        return socket.getLocalPort();
      } catch (Exception e) {
        // ignore this
      }
    }
    throw new IOException("No available port in the portRange: " + portRange);
  }

  public static boolean checkIfRemoteEndpointAccessible(String host, int port) {
    try {
      Socket discover = new Socket();
      discover.setSoTimeout(1000);
      discover.connect(new InetSocketAddress(host, port), 1000);
      discover.close();
      return true;
    } catch (ConnectException cne) {
      // end point is not accessible
      if (LOGGER.isDebugEnabled()) {
        LOGGER.debug("Remote endpoint '" + host + ":" + port + "' is not accessible " +
                "(might be initializing): " + cne.getMessage());
      }
      return false;
    } catch (IOException ioe) {
      // end point is not accessible
      if (LOGGER.isDebugEnabled()) {
        LOGGER.debug("Remote endpoint '" + host + ":" + port + "' is not accessible " +
                "(might be initializing): " + ioe.getMessage());
      }
      return false;
    }
  }
}