//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.websocket.server;
  
  import java.io.IOException;
  
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.common.AcceptHash;
  import org.eclipse.jetty.websocket.servlet.ServletUpgradeRequest;
  import org.eclipse.jetty.websocket.servlet.ServletUpgradeResponse;
  
  /**
   * WebSocket Handshake for <a href="https://tools.ietf.org/html/rfc6455">RFC 6455</a>.
   */
  public class HandshakeRFC6455 implements WebSocketHandshake
  {
      /** RFC 6455 - Sec-WebSocket-Version */
      public static final int VERSION = 13;
  
      @Override
      public void doHandshakeResponse(ServletUpgradeRequest request, ServletUpgradeResponse response) throws IOException
      {
          String key = request.getHeader("Sec-WebSocket-Key");
  
          if (key == null)
          {
              throw new IllegalStateException("Missing request header 'Sec-WebSocket-Key'");
          }
  
          // build response
          response.setHeader("Upgrade","WebSocket");
          response.addHeader("Connection","Upgrade");
          response.addHeader("Sec-WebSocket-Accept",AcceptHash.hashKey(key));
  
          if (response.getExtensions() != null)
          {
              String value = ExtensionConfig.toHeaderValue(response.getExtensions());
              if (value != null)
              {
                  response.addHeader("Sec-WebSocket-Extensions",value);
              }
          }
  
          request.complete();
  
          response.setStatus(HttpServletResponse.SC_SWITCHING_PROTOCOLS);
          response.complete();
      }
  }