//
   //  ========================================================================
   //  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.security.authentication;
  
  import java.io.IOException;
  
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.security.ServerAuthException;
  import org.eclipse.jetty.security.UserAuthentication;
  import org.eclipse.jetty.server.Authentication;
  import org.eclipse.jetty.server.Authentication.User;
  import org.eclipse.jetty.server.UserIdentity;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.security.Constraint;
  
  public class SpnegoAuthenticator extends LoginAuthenticator
  {
      private static final Logger LOG = Log.getLogger(SpnegoAuthenticator.class);
      private String _authMethod = Constraint.__SPNEGO_AUTH;
  
      public SpnegoAuthenticator()
      {
      }
  
      /**
       * Allow for a custom authMethod value to be set for instances where SPENGO may not be appropriate
       * @param authMethod the auth method
       */
      public SpnegoAuthenticator( String authMethod )
      {
          _authMethod = authMethod;
      }
  
      @Override
      public String getAuthMethod()
      {
          return _authMethod;
      }
  
      @Override
      public Authentication validateRequest(ServletRequest request, ServletResponse response, boolean mandatory) throws ServerAuthException
      {
          HttpServletRequest req = (HttpServletRequest)request;
          HttpServletResponse res = (HttpServletResponse)response;
  
          String header = req.getHeader(HttpHeader.AUTHORIZATION.asString());
  
          if (!mandatory)
          {
              return new DeferredAuthentication(this);
          }
  
          // check to see if we have authorization headers required to continue
          if ( header == null )
          {
              try
              {
                   if (DeferredAuthentication.isDeferred(res))
                   {
                       return Authentication.UNAUTHENTICATED;
                   }
  
                  LOG.debug("SpengoAuthenticator: sending challenge");
                  res.setHeader(HttpHeader.WWW_AUTHENTICATE.asString(), HttpHeader.NEGOTIATE.asString());
                  res.sendError(HttpServletResponse.SC_UNAUTHORIZED);
                  return Authentication.SEND_CONTINUE;
              }
              catch (IOException ioe)
              {
                  throw new ServerAuthException(ioe);
              }
          }
          else if (header != null && header.startsWith(HttpHeader.NEGOTIATE.asString()))
          {
              String spnegoToken = header.substring(10);
  
              UserIdentity user = login(null,spnegoToken, request);
 
             if ( user != null )
             {
                 return new UserAuthentication(getAuthMethod(),user);
             }
         }
 
         return Authentication.UNAUTHENTICATED;
     }
 
     @Override
     public boolean secureResponse(ServletRequest request, ServletResponse response, boolean mandatory, User validatedUser) throws ServerAuthException
     {
         return true;
     }
 
 }