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.grid.security;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import java.net.HttpURLConnection;
  import java.util.Base64;
  import java.util.logging.Logger;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.http.Filter;
  import org.openqa.selenium.remote.http.HttpHandler;
  import org.openqa.selenium.remote.http.HttpResponse;
  
  public class BasicAuthenticationFilter implements Filter {
  
    private static final Logger LOG = Logger.getLogger(BasicAuthenticationFilter.class.getName());
    private final String passphrase;
  
    public BasicAuthenticationFilter(String user, String password) {
      passphrase = Base64.getEncoder().encodeToString((user + ":" + password).getBytes(UTF_8));
    }
  
    @Override
    public HttpHandler apply(HttpHandler next) {
      return req -> {
        Require.nonNull("Request", req);
  
        String auth = req.getHeader("Authorization");
        if (!isAuthorized(auth)) {
          if (auth != null) {
            LOG.info("Unauthorized request to " + req);
          }
          return new HttpResponse()
              .setStatus(HttpURLConnection.HTTP_UNAUTHORIZED)
              .addHeader("WWW-Authenticate", "Basic realm=\"selenium-server\"");
        }
  
        return next.execute(req);
      };
    }
  
    private boolean isAuthorized(String auth) {
      if (auth != null) {
        final int index = auth.indexOf(' ') + 1;
  
        if (index > 0) {
          return passphrase.equals(auth.substring(index));
        }
      }
  
      return false;
    }
  }
  