//
   //  ========================================================================
   //  Copyright (c) 1995-2015 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.server;
  
  import java.net.InetSocketAddress;
  
  import javax.servlet.ServletRequest;
  
  import org.eclipse.jetty.http.HostPortHttpField;
  import org.eclipse.jetty.http.HttpFields;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpScheme;
  import org.eclipse.jetty.server.HttpConfiguration.Customizer;
  
  
  /* ------------------------------------------------------------ */
  /** Customize Requests for Proxy Forwarding.
   * <p>
   * This customizer looks at at HTTP request for headers that indicate
   * it has been forwarded by one or more proxies.  Specifically handled are:
   * <ul>
   * <li>X-Forwarded-Host</li>
   * <li>X-Forwarded-Server</li>
   * <li>X-Forwarded-For</li>
   * <li>X-Forwarded-Proto</li>
   * </ul>
   * <p>If these headers are present, then the {@link Request} object is updated
   * so that the proxy is not seen as the other end point of the connection on which
   * the request came</p>
   * <p>Headers can also be defined so that forwarded SSL Session IDs and Cipher
   * suites may be customised</p> 
   * @see <a href="http://en.wikipedia.org/wiki/X-Forwarded-For">Wikipedia: X-Forwarded-For</a>
   */
  public class ForwardedRequestCustomizer implements Customizer
  {
      private HostPortHttpField _hostHeader;
      private String _forwardedHostHeader = HttpHeader.X_FORWARDED_HOST.toString();
      private String _forwardedServerHeader = HttpHeader.X_FORWARDED_SERVER.toString();
      private String _forwardedForHeader = HttpHeader.X_FORWARDED_FOR.toString();
      private String _forwardedProtoHeader = HttpHeader.X_FORWARDED_PROTO.toString();
      private String _forwardedCipherSuiteHeader;
      private String _forwardedSslSessionIdHeader;
      
  
      /* ------------------------------------------------------------ */
      public String getHostHeader()
      {
          return _hostHeader.getValue();
      }
  
      /* ------------------------------------------------------------ */
      /**
       * Set a forced valued for the host header to control what is returned by {@link ServletRequest#getServerName()} and {@link ServletRequest#getServerPort()}.
       *
       * @param hostHeader
       *            The value of the host header to force.
       */
      public void setHostHeader(String hostHeader)
      {
          _hostHeader = new HostPortHttpField(hostHeader);
      }
  
      /* ------------------------------------------------------------ */
      /*
       *
       * @see #setForwarded(boolean)
       */
      public String getForwardedHostHeader()
      {
          return _forwardedHostHeader;
      }
  
      /* ------------------------------------------------------------ */
      /**
       * @param forwardedHostHeader
       *            The header name for forwarded hosts (default x-forwarded-host)
       */
      public void setForwardedHostHeader(String forwardedHostHeader)
      {
          _forwardedHostHeader = forwardedHostHeader;
      }
  
      /* ------------------------------------------------------------ */
     /**
      * @return the header name for forwarded server.
      */
     public String getForwardedServerHeader()
     {
         return _forwardedServerHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param forwardedServerHeader
      *            The header name for forwarded server (default x-forwarded-server)
      */
     public void setForwardedServerHeader(String forwardedServerHeader)
     {
         _forwardedServerHeader = forwardedServerHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return the forwarded for header
      */
     public String getForwardedForHeader()
     {
         return _forwardedForHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param forwardedRemoteAddressHeader
      *            The header name for forwarded for (default x-forwarded-for)
      */
     public void setForwardedForHeader(String forwardedRemoteAddressHeader)
     {
         _forwardedForHeader = forwardedRemoteAddressHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Get the forwardedProtoHeader.
      *
      * @return the forwardedProtoHeader (default X-Forwarded-For)
      */
     public String getForwardedProtoHeader()
     {
         return _forwardedProtoHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the forwardedProtoHeader.
      *
      * @param forwardedProtoHeader
      *            the forwardedProtoHeader to set (default X-Forwarded-For)
      */
     public void setForwardedProtoHeader(String forwardedProtoHeader)
     {
         _forwardedProtoHeader = forwardedProtoHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return The header name holding a forwarded cipher suite (default null)
      */
     public String getForwardedCipherSuiteHeader()
     {
         return _forwardedCipherSuiteHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param forwardedCipherSuite
      *            The header name holding a forwarded cipher suite (default null)
      */
     public void setForwardedCipherSuiteHeader(String forwardedCipherSuite)
     {
         _forwardedCipherSuiteHeader = forwardedCipherSuite;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return The header name holding a forwarded SSL Session ID (default null)
      */
     public String getForwardedSslSessionIdHeader()
     {
         return _forwardedSslSessionIdHeader;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param forwardedSslSessionId
      *            The header name holding a forwarded SSL Session ID (default null)
      */
     public void setForwardedSslSessionIdHeader(String forwardedSslSessionId)
     {
         _forwardedSslSessionIdHeader = forwardedSslSessionId;
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public void customize(Connector connector, HttpConfiguration config, Request request)
     {
         HttpFields httpFields = request.getHttpFields();
 
         // Do SSL first
         if (getForwardedCipherSuiteHeader()!=null)
         {
             String cipher_suite=httpFields.get(getForwardedCipherSuiteHeader());
             if (cipher_suite!=null)
                 request.setAttribute("javax.servlet.request.cipher_suite",cipher_suite);
         }
         if (getForwardedSslSessionIdHeader()!=null)
         {
             String ssl_session_id=httpFields.get(getForwardedSslSessionIdHeader());
             if(ssl_session_id!=null)
             {
                 request.setAttribute("javax.servlet.request.ssl_session_id", ssl_session_id);
                 request.setScheme(HttpScheme.HTTPS.asString());
             }
         }
 
         // Retrieving headers from the request
         String forwardedHost = getLeftMostFieldValue(httpFields,getForwardedHostHeader());
         String forwardedServer = getLeftMostFieldValue(httpFields,getForwardedServerHeader());
         String forwardedFor = getLeftMostFieldValue(httpFields,getForwardedForHeader());
         String forwardedProto = getLeftMostFieldValue(httpFields,getForwardedProtoHeader());
 
         if (_hostHeader != null)
         {
             // Update host header
             httpFields.put(_hostHeader);
             request.setAuthority(_hostHeader.getHost(),_hostHeader.getPort());
         }
         else if (forwardedHost != null)
         {
             // Update host header
             HostPortHttpField auth = new HostPortHttpField(forwardedHost);
             httpFields.put(auth);
             request.setAuthority(auth.getHost(),auth.getPort());
         }
         else if (forwardedServer != null)
         {
             // Use provided server name
             request.setAuthority(forwardedServer,request.getServerPort());
         }
 
         if (forwardedFor != null)
         {
             request.setRemoteAddr(InetSocketAddress.createUnresolved(forwardedFor,request.getRemotePort()));
         }
 
         if (forwardedProto != null)
         {
             request.setScheme(forwardedProto);
             if (forwardedProto.equals(config.getSecureScheme()))
                 request.setSecure(true);
         }
     }
 
     /* ------------------------------------------------------------ */
     protected String getLeftMostFieldValue(HttpFields fields, String header)
     {
         if (header == null)
             return null;
 
         String headerValue = fields.get(header);
 
         if (headerValue == null)
             return null;
 
         int commaIndex = headerValue.indexOf(',');
 
         if (commaIndex == -1)
         {
             // Single value
             return headerValue;
         }
 
         // The left-most value is the farthest downstream client
         return headerValue.substring(0,commaIndex);
     }
 
 
     /* ------------------------------------------------------------ */
     @Override
     public String toString()
     {
         return String.format("%s@%x",this.getClass().getSimpleName(),hashCode());
     }
 }