code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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.openqa.selenium.net;
  
  import java.net.InetAddress;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.List;
  import org.openqa.selenium.Platform;
  import org.openqa.selenium.WebDriverException;
  
  public class DefaultNetworkInterfaceProvider implements NetworkInterfaceProvider {
    // Cache the list of interfaces between instances. This is mostly used
    // to get the loopback interface, so it's ok even though interfaces may go
    // up and down during the test.
    // Caching the result of getNetworkInterfaces saves 2 seconds, which is
    // significant when running the tests.
    private final List<NetworkInterface> cachedInterfaces;
  
    @Override
    public Iterable<NetworkInterface> getNetworkInterfaces() {
      return cachedInterfaces;
    }
  
    public DefaultNetworkInterfaceProvider() {
      Enumeration<java.net.NetworkInterface> interfaces;
      try {
        interfaces = java.net.NetworkInterface.getNetworkInterfaces();
      } catch (SocketException e) {
        throw new WebDriverException(e);
      }
  
      // If we can find the default network interface, use that. We want to avoid using
      // InetAddress.getLocalHost() since that does a reverse DNS lookup, which may be slow.
      InetAddress defaultAddress = null;
      if (!"Unknown".equals(HostIdentifier.getHostAddress())) {
        try {
          defaultAddress = InetAddress.getByName(HostIdentifier.getHostAddress());
        } catch (UnknownHostException e) {
          // OK. Fall through.
        }
      }
  
      List<NetworkInterface> result = new ArrayList<>();
      boolean defaultFound = false;
      while (interfaces.hasMoreElements()) {
        java.net.NetworkInterface jvmNic = interfaces.nextElement();
  
        try {
          // If the NIC isn't a loopback device and also lacks a hardware
          // address, it's likely to be impossible to connect to. We see
          // this with `utun` NICS on macOS. Skip these from the list of
          // cached NICs.
          if (!jvmNic.isLoopback() && jvmNic.getHardwareAddress() == null) {
            continue;
          }
        } catch (SocketException e) {
          continue;
        }
  
        NetworkInterface nic = new NetworkInterface(jvmNic);
        result.add(nic);
  
        if (defaultAddress == null || defaultFound) {
          continue;
        }
  
        Enumeration<InetAddress> inetAddresses = jvmNic.getInetAddresses();
        while (inetAddresses.hasMoreElements() && !defaultFound) {
          InetAddress address = inetAddresses.nextElement();
          if (defaultAddress.equals(address)) {
            result.add(0, nic);
            defaultFound = true;
          }
        }
      }
      this.cachedInterfaces = Collections.unmodifiableList(result);
    }
  
    private String getLocalInterfaceName() {
      if (Platform.getCurrent().is(Platform.MAC)) {
        return "lo0";
      }
  
      return "lo";
    }
  
    @Override
    public NetworkInterface getLoInterface() {
      final String localIF = getLocalInterfaceName();
      try {
        final java.net.NetworkInterface byName = java.net.NetworkInterface.getByName(localIF);
        return (byName != null) ? new NetworkInterface(byName) : null;
      } catch (SocketException e) {
        throw new WebDriverException(e);
      }
    }
  }
  