content: /**
   * 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.activemq.transport.http;
  
  import java.io.*;
  import java.util.HashMap;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.TimeUnit;
  import java.util.zip.GZIPInputStream;
  import jakarta.jms.JMSException;
  import jakarta.servlet.ServletException;
  import jakarta.servlet.http.HttpServlet;
  import jakarta.servlet.http.HttpServletRequest;
  import jakarta.servlet.http.HttpServletResponse;
  
  import org.apache.activemq.Service;
  import org.apache.activemq.command.Command;
  import org.apache.activemq.command.ConnectionInfo;
  import org.apache.activemq.command.ShutdownInfo;
  import org.apache.activemq.command.WireFormatInfo;
  import org.apache.activemq.transport.Transport;
  import org.apache.activemq.transport.TransportAcceptListener;
  import org.apache.activemq.transport.util.TextWireFormat;
  import org.apache.activemq.transport.xstream.XStreamWireFormat;
  import org.apache.activemq.util.IOExceptionSupport;
  import org.apache.activemq.util.ServiceListener;
  import org.apache.http.HttpStatus;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A servlet which handles server side HTTP transport, delegating to the
   * ActiveMQ broker. This servlet is designed for being embedded inside an
   * ActiveMQ Broker using an embedded Jetty or Tomcat instance.
   */
  public class HttpTunnelServlet extends HttpServlet {
      private static final long serialVersionUID = -3826714430767484333L;
      private static final Logger LOG = LoggerFactory.getLogger(HttpTunnelServlet.class);
  
      private TransportAcceptListener listener;
      private HttpTransportFactory transportFactory;
      private TextWireFormat wireFormat;
      private ConcurrentMap<String, BlockingQueueTransport> clients = new ConcurrentHashMap<String, BlockingQueueTransport>();
      private final long requestTimeout = 30000L;
      private HashMap<String, Object> transportOptions;
      private HashMap<String, Object> wireFormatOptions;
  
      @SuppressWarnings("unchecked")
      @Override
      public void init() throws ServletException {
          super.init();
          listener = (TransportAcceptListener)getServletContext().getAttribute("acceptListener");
          if (listener == null) {
              throw new ServletException("No such attribute 'acceptListener' available in the ServletContext");
          }
          transportFactory = (HttpTransportFactory)getServletContext().getAttribute("transportFactory");
          if (transportFactory == null) {
              throw new ServletException("No such attribute 'transportFactory' available in the ServletContext");
          }
          transportOptions = (HashMap<String, Object>)getServletContext().getAttribute("transportOptions");
          wireFormatOptions = (HashMap<String, Object>)getServletContext().getAttribute("wireFormatOptions");
          wireFormat = (TextWireFormat)getServletContext().getAttribute("wireFormat");
          if (wireFormat == null) {
              wireFormat = createWireFormat();
          }
      }
  
      @Override
      protected void doOptions(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          response.addHeader("Accepts-Encoding", "gzip");
          super.doOptions(request, response);
      }
  
      @Override
      protected void doHead(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          createTransportChannel(request, response);
      }
  
      @Override
      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          // lets return the next response
          Command packet = null;
          int count = 0;
          try {
              BlockingQueueTransport transportChannel = getTransportChannel(request, response);
              if (transportChannel == null) {
                  return;
              }
  
              packet = (Command)transportChannel.getQueue().poll(requestTimeout, TimeUnit.MILLISECONDS);
  
              // If the packet is ShutDownInfo then we are shutting down so return.
              if (packet instanceof ShutdownInfo) {
                  return;
              }
  
              DataOutputStream stream = new DataOutputStream(response.getOutputStream());
              wireFormat.marshal(packet, stream);
              count++;
          } catch (InterruptedException ignore) {
          }
  
          if (count == 0) {
              response.setStatus(HttpServletResponse.SC_REQUEST_TIMEOUT);
          }
      }
  
      @Override
      protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          try {
              if (wireFormatOptions.get("maxFrameSize") != null && request.getContentLength() > Integer.parseInt(wireFormatOptions.get("maxFrameSize").toString())) {
                  response.setStatus(405);
                  response.setContentType("plain/text");
                  PrintWriter writer = response.getWriter();
                  writer.println("maxFrameSize exceeded");
                  writer.flush();
                  writer.close();
                  return;
              }
  
              InputStream stream = request.getInputStream();
              String contentType = request.getContentType();
              if (contentType != null && contentType.equals("application/x-gzip")) {
                  stream = new GZIPInputStream(stream);
              }
  
              // Read the command directly from the reader, assuming UTF8 encoding
              Command command = (Command) wireFormat.unmarshalText(new InputStreamReader(stream, "UTF-8"));
  
              if (command instanceof WireFormatInfo) {
                  WireFormatInfo info = (WireFormatInfo) command;
                  if (!canProcessWireFormatVersion(info.getVersion())) {
                      response.sendError(HttpServletResponse.SC_NOT_FOUND, "Cannot process wire format of version: "
                              + info.getVersion());
                  }
  
              } else {
  
                  BlockingQueueTransport transport = getTransportChannel(request, response);
                  if (transport == null) {
                      return;
                  }
  
                  if (command instanceof ConnectionInfo) {
                      ((ConnectionInfo) command).setTransportContext(request.getAttribute("jakarta.servlet.request.X509Certificate"));
                  }
                  transport.doConsume(command);
              }
          } catch (Exception e) {
              // no stack trace
              if (wireFormatOptions.get("sendStackTrace") != null && Boolean.parseBoolean(wireFormatOptions.get("sendStackTrace").toString()) == false) {
                  LOG.warn(e.getMessage(), e);
                  response.sendError(HttpStatus.SC_INTERNAL_SERVER_ERROR);
              } else {
                  throw e;
              }
          }
      }
  
      private boolean canProcessWireFormatVersion(int version) {
          return true;
      }
  
      protected BlockingQueueTransport getTransportChannel(HttpServletRequest request, HttpServletResponse response) throws IOException {
          String clientID = request.getHeader("clientID");
          if (clientID == null) {
              response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No clientID header specified");
              LOG.warn("No clientID header specified");
              return null;
          }
          BlockingQueueTransport answer = clients.get(clientID);
          if (answer == null) {
              LOG.warn("The clientID header specified is invalid. Client session has not yet been established for it: " + clientID);
              return null;
          }
          return answer;
      }
  
      protected BlockingQueueTransport createTransportChannel(HttpServletRequest request, HttpServletResponse response) throws IOException {
          final String clientID = request.getHeader("clientID");
  
          if (clientID == null) {
              response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No clientID header specified");
              LOG.warn("No clientID header specified");
              return null;
          }
  
          // Optimistically create the client's transport; this transport may be thrown away if the client has already registered.
          BlockingQueueTransport answer = createTransportChannel();
  
          // Record the client's transport and ensure that it has not already registered; this is thread-safe and only allows one
          // thread to register the client
          if (clients.putIfAbsent(clientID, answer) != null) {
              response.sendError(HttpServletResponse.SC_BAD_REQUEST, "A session for the given clientID has already been established");
              LOG.warn("A session for clientID '" + clientID + "' has already been established");
              return null;
          }
  
          // Ensure that the client's transport is cleaned up when no longer
          // needed.
          answer.addServiceListener(new ServiceListener() {
              public void started(Service service) {
                  // Nothing to do.
              }
  
              public void stopped(Service service) {
                  final BlockingQueueTransport removed = clients.remove(clientID);
                  if (removed != null) {
                      try {
                          // Send a ShutdownInfo() packet on stop so that we unblock any calls
                          // to transportChannel.getQueue().poll()
                          removed.getQueue().add(new ShutdownInfo());
                      } catch (Exception e) {
                          LOG.debug("Could not send ShutdownInfo() packet to BlockingQueueTransport "
                              + "on shutdown for client {}", clientID);
                      }
                  }
              }
          });
  
          // Configure the transport with any additional properties or filters.  Although the returned transport is not explicitly
          // persisted, if it is a filter (e.g., InactivityMonitor) it will be linked to the client's transport as a TransportListener
          // and not GC'd until the client's transport is disposed.
          Transport transport = answer;
          try {
              // Preserve the transportOptions for future use by making a copy before applying (they are removed when applied).
              HashMap<String, Object> options = new HashMap<String, Object>(transportOptions);
              transport = transportFactory.serverConfigure(answer, null, options);
          } catch (Exception e) {
              throw IOExceptionSupport.create(e);
          }
  
          // Wait for the transport to be connected or disposed.
          listener.onAccept(transport);
          while (!transport.isConnected() && !transport.isDisposed()) {
              try {
                  Thread.sleep(100);
              } catch (InterruptedException ignore) {
              }
          }
  
          // Ensure that the transport was not prematurely disposed.
          if (transport.isDisposed()) {
              response.sendError(HttpServletResponse.SC_BAD_REQUEST, "The session for the given clientID was prematurely disposed");
              LOG.warn("The session for clientID '" + clientID + "' was prematurely disposed");
              return null;
          }
  
          return answer;
      }
  
      protected BlockingQueueTransport createTransportChannel() {
         return new BlockingQueueTransport(new LinkedBlockingQueue<Object>());
      }
  
      protected TextWireFormat createWireFormat() {
          return new XStreamWireFormat();
      }
  }
  