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.node;
  
  import static org.openqa.selenium.internal.Debug.getDebugLogLevel;
  import static org.openqa.selenium.remote.http.HttpMethod.GET;
  
  import com.google.common.collect.ImmutableSet;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.function.BiFunction;
  import java.util.function.Consumer;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  import java.util.stream.Stream;
  import org.openqa.selenium.Capabilities;
  import org.openqa.selenium.devtools.CdpEndpointFinder;
  import org.openqa.selenium.grid.data.Session;
  import org.openqa.selenium.remote.SessionId;
  import org.openqa.selenium.remote.http.BinaryMessage;
  import org.openqa.selenium.remote.http.ClientConfig;
  import org.openqa.selenium.remote.http.CloseMessage;
  import org.openqa.selenium.remote.http.HttpClient;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.Message;
  import org.openqa.selenium.remote.http.TextMessage;
  import org.openqa.selenium.remote.http.UrlTemplate;
  import org.openqa.selenium.remote.http.WebSocket;
  
  public class ProxyNodeWebsockets
      implements BiFunction<String, Consumer<Message>, Optional<Consumer<Message>>> {
  
    private static final UrlTemplate CDP_TEMPLATE = new UrlTemplate("/session/{sessionId}/se/cdp");
    private static final UrlTemplate BIDI_TEMPLATE = new UrlTemplate("/session/{sessionId}/se/bidi");
    private static final UrlTemplate FWD_TEMPLATE = new UrlTemplate("/session/{sessionId}/se/fwd");
    private static final UrlTemplate VNC_TEMPLATE = new UrlTemplate("/session/{sessionId}/se/vnc");
    private static final Logger LOG = Logger.getLogger(ProxyNodeWebsockets.class.getName());
    private static final ImmutableSet<String> CDP_ENDPOINT_CAPS =
        ImmutableSet.of("goog:chromeOptions", "moz:debuggerAddress", "ms:edgeOptions");
    private final HttpClient.Factory clientFactory;
    private final Node node;
  
    public ProxyNodeWebsockets(HttpClient.Factory clientFactory, Node node) {
      this.clientFactory = Objects.requireNonNull(clientFactory);
      this.node = Objects.requireNonNull(node);
    }
  
    @Override
    public Optional<Consumer<Message>> apply(String uri, Consumer<Message> downstream) {
      UrlTemplate.Match fwdMatch = FWD_TEMPLATE.match(uri);
      UrlTemplate.Match cdpMatch = CDP_TEMPLATE.match(uri);
      UrlTemplate.Match bidiMatch = BIDI_TEMPLATE.match(uri);
      UrlTemplate.Match vncMatch = VNC_TEMPLATE.match(uri);
  
      if (bidiMatch == null && cdpMatch == null && vncMatch == null && fwdMatch == null) {
        return Optional.empty();
      }
  
      String sessionId =
          Stream.of(fwdMatch, cdpMatch, bidiMatch, vncMatch)
              .filter(Objects::nonNull)
              .findFirst()
              .get()
              .getParameters()
              .get("sessionId");
  
      LOG.fine("Matching websockets for session id: " + sessionId);
      SessionId id = new SessionId(sessionId);
  
      if (!node.isSessionOwner(id)) {
        LOG.info("Not owner of " + id);
        return Optional.empty();
      }
  
      Session session = node.getSession(id);
      Capabilities caps = session.getCapabilities();
      LOG.fine("Scanning for endpoint: " + caps);
  
      if (bidiMatch != null) {
        return findBiDiEndpoint(downstream, caps);
      }
  
      if (vncMatch != null) {
        return findVncEndpoint(downstream, caps);
      }
  
      // This match happens when a user wants to do CDP over Dynamic Grid
      if (fwdMatch != null) {
        LOG.info("Matched endpoint where CDP connection is being forwarded");
        return findCdpEndpoint(downstream, caps);
      }
      if (caps.getCapabilityNames().contains("se:forwardCdp")) {
        LOG.info("Found endpoint where CDP connection needs to be forwarded");
        return findForwardCdpEndpoint(downstream, caps);
      }
      return findCdpEndpoint(downstream, caps);
    }
  
    private Optional<Consumer<Message>> findCdpEndpoint(
        Consumer<Message> downstream, Capabilities caps) {
      // Using strings here to avoid Node depending upon specific drivers.
      for (String cdpEndpointCap : CDP_ENDPOINT_CAPS) {
        Optional<URI> reportedUri = CdpEndpointFinder.getReportedUri(cdpEndpointCap, caps);
        Optional<HttpClient> client =
            reportedUri.map(uri -> CdpEndpointFinder.getHttpClient(clientFactory, uri));
        Optional<URI> cdpUri;
  
        try {
          cdpUri = client.flatMap(httpClient -> CdpEndpointFinder.getCdpEndPoint(httpClient));
        } catch (Exception e) {
          try {
            client.ifPresent(HttpClient::close);
          } catch (Exception ex) {
            e.addSuppressed(ex);
          }
          throw e;
        }
  
        if (cdpUri.isPresent()) {
          LOG.log(getDebugLogLevel(), String.format("Endpoint found in %s", cdpEndpointCap));
          return cdpUri.map(cdp -> createWsEndPoint(cdp, downstream));
        } else {
          try {
            client.ifPresent(HttpClient::close);
          } catch (Exception e) {
            LOG.log(
                Level.FINE,
                "failed to close the http client used to check the reported CDP endpoint: "
                    + reportedUri.get(),
                e);
          }
        }
      }
      return Optional.empty();
    }
  
    private Optional<Consumer<Message>> findBiDiEndpoint(
        Consumer<Message> downstream, Capabilities caps) {
      try {
        URI uri = new URI(String.valueOf(caps.getCapability("webSocketUrl")));
        return Optional.of(uri).map(bidi -> createWsEndPoint(bidi, downstream));
      } catch (URISyntaxException e) {
        LOG.warning("Unable to create URI from: " + caps.getCapability("webSocketUrl"));
        return Optional.empty();
      }
    }
  
    private Optional<Consumer<Message>> findForwardCdpEndpoint(
        Consumer<Message> downstream, Capabilities caps) {
      // When using Dynamic Grid, we need to connect to a container before using the debuggerAddress
      try {
        URI uri = new URI(String.valueOf(caps.getCapability("se:forwardCdp")));
        return Optional.of(uri).map(cdp -> createWsEndPoint(cdp, downstream));
      } catch (URISyntaxException e) {
        LOG.warning("Unable to create URI from: " + caps.getCapability("se:forwardCdp"));
        return Optional.empty();
      }
    }
  
    private Optional<Consumer<Message>> findVncEndpoint(
        Consumer<Message> downstream, Capabilities caps) {
      String vncLocalAddress = (String) caps.getCapability("se:vncLocalAddress");
      Optional<URI> vncUri;
      try {
        vncUri = Optional.of(new URI(vncLocalAddress));
      } catch (URISyntaxException e) {
        LOG.warning("Invalid URI for endpoint " + vncLocalAddress);
        return Optional.empty();
      }
      LOG.log(getDebugLogLevel(), String.format("Endpoint found in %s", "se:vncLocalAddress"));
      return vncUri.map(vnc -> createWsEndPoint(vnc, downstream));
    }
  
    private Consumer<Message> createWsEndPoint(URI uri, Consumer<Message> downstream) {
      Objects.requireNonNull(uri);
  
      LOG.info("Establishing connection to " + uri);
  
      HttpClient client = clientFactory.createClient(ClientConfig.defaultConfig().baseUri(uri));
      WebSocket upstream =
          client.openSocket(new HttpRequest(GET, uri.toString()), new ForwardingListener(downstream));
      return upstream::send;
    }
  
    private static class ForwardingListener implements WebSocket.Listener {
      private final Consumer<Message> downstream;
  
      public ForwardingListener(Consumer<Message> downstream) {
        this.downstream = Objects.requireNonNull(downstream);
      }
  
      @Override
      public void onBinary(byte[] data) {
        downstream.accept(new BinaryMessage(data));
      }
  
      @Override
      public void onClose(int code, String reason) {
        downstream.accept(new CloseMessage(code, reason));
      }
  
      @Override
      public void onText(CharSequence data) {
        downstream.accept(new TextMessage(data));
      }
  
      @Override
      public void onError(Throwable cause) {
        LOG.log(Level.WARNING, "Error proxying websocket command", cause);
      }
    }
  }
  