/**
    * Waffle (https://github.com/dblock/waffle)
    *
    * Copyright (c) 2010 - 2015 Application Security, Inc.
    *
    * All rights reserved. This program and the accompanying materials
    * are made available under the terms of the Eclipse Public License v1.0
    * which accompanies this distribution, and is available at
    * http://www.eclipse.org/legal/epl-v10.html
   *
   * Contributors:
   *     Application Security, Inc.
   */
  package waffle.apache;
  
  import java.io.IOException;
  import java.security.Principal;
  
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  
  import org.apache.catalina.LifecycleException;
  import org.apache.catalina.connector.Request;
  import org.slf4j.LoggerFactory;
  
  import com.google.common.io.BaseEncoding;
  import com.sun.jna.platform.win32.Win32Exception;
  
  import waffle.util.AuthorizationHeader;
  import waffle.util.NtlmServletRequest;
  import waffle.windows.auth.IWindowsIdentity;
  import waffle.windows.auth.IWindowsSecurityContext;
  
  /**
   * An Apache Negotiate (NTLM, Kerberos) Authenticator.
   * 
   * @author dblock[at]dblock[dot]org
   */
  public class NegotiateAuthenticator extends WaffleAuthenticatorBase {
  
      /**
       * Instantiates a new negotiate authenticator.
       */
      public NegotiateAuthenticator() {
          super();
          this.log = LoggerFactory.getLogger(NegotiateAuthenticator.class);
          this.info = "waffle.apache.NegotiateAuthenticator/1.0";
          this.log.debug("[waffle.apache.NegotiateAuthenticator] loaded");
      }
  
      /* (non-Javadoc)
       * @see org.apache.catalina.authenticator.AuthenticatorBase#startInternal()
       */
      @Override
      public synchronized void startInternal() throws LifecycleException {
          this.log.info("[waffle.apache.NegotiateAuthenticator] started");
          super.startInternal();
      }
  
      /* (non-Javadoc)
       * @see org.apache.catalina.authenticator.AuthenticatorBase#stopInternal()
       */
      @Override
      public synchronized void stopInternal() throws LifecycleException {
          super.stopInternal();
          this.log.info("[waffle.apache.NegotiateAuthenticator] stopped");
      }
  
      /* (non-Javadoc)
       * @see org.apache.catalina.authenticator.AuthenticatorBase#authenticate(org.apache.catalina.connector.Request, javax.servlet.http.HttpServletResponse)
       */
      @Override
      public boolean authenticate(final Request request, final HttpServletResponse response) {
  
          Principal principal = request.getUserPrincipal();
          final AuthorizationHeader authorizationHeader = new AuthorizationHeader(request);
          final boolean ntlmPost = authorizationHeader.isNtlmType1PostAuthorizationHeader();
  
          this.log.debug("{} {}, contentlength: {}", request.getMethod(), request.getRequestURI(),
                  Integer.valueOf(request.getContentLength()));
          this.log.debug("authorization: {}, ntlm post: {}", authorizationHeader, Boolean.valueOf(ntlmPost));
  
          if (principal != null && !ntlmPost) {
              // user already authenticated
              this.log.debug("previously authenticated user: {}", principal.getName());
              return true;
          }
  
          // authenticate user
          if (!authorizationHeader.isNull()) {
  
              final String securityPackage = authorizationHeader.getSecurityPackage();
              // maintain a connection-based session for NTLM tokens
              final String connectionId = NtlmServletRequest.getConnectionId(request);
  
              this.log.debug("security package: {}, connection id: {}", securityPackage, connectionId);
  
              if (ntlmPost) {
                  // type 1 NTLM authentication message received
                 this.auth.resetSecurityToken(connectionId);
             }
 
             // log the user in using the token
             IWindowsSecurityContext securityContext;
 
             try {
                 final byte[] tokenBuffer = authorizationHeader.getTokenBytes();
                 this.log.debug("token buffer: {} byte(s)", Integer.valueOf(tokenBuffer.length));
                 try {
                     securityContext = this.auth.acceptSecurityToken(connectionId, tokenBuffer, securityPackage);
                 } catch (final Win32Exception e) {
                     this.log.warn("error logging in user: {}", e.getMessage());
                     this.log.trace("{}", e);
                     this.sendUnauthorized(response);
                     return false;
                 }
                 this.log.debug("continue required: {}", Boolean.valueOf(securityContext.isContinue()));
 
                 final byte[] continueTokenBytes = securityContext.getToken();
                 if (continueTokenBytes != null && continueTokenBytes.length > 0) {
                     final String continueToken = BaseEncoding.base64().encode(continueTokenBytes);
                     this.log.debug("continue token: {}", continueToken);
                     response.addHeader("WWW-Authenticate", securityPackage + " " + continueToken);
                 }
 
                 if (securityContext.isContinue() || ntlmPost) {
                     response.setHeader("Connection", "keep-alive");
                     response.sendError(HttpServletResponse.SC_UNAUTHORIZED);
                     response.flushBuffer();
                     return false;
                 }
 
             } catch (final IOException e) {
                 this.log.warn("error logging in user: {}", e.getMessage());
                 this.log.trace("{}", e);
                 this.sendUnauthorized(response);
                 return false;
             }
 
             // realm: fail if no realm is configured
             if (this.context == null || this.context.getRealm() == null) {
                 this.log.warn("missing context/realm");
                 this.sendError(response, HttpServletResponse.SC_SERVICE_UNAVAILABLE);
                 return false;
             }
 
             // create and register the user principal with the session
             final IWindowsIdentity windowsIdentity = securityContext.getIdentity();
 
             // disable guest login
             if (!this.allowGuestLogin && windowsIdentity.isGuest()) {
                 this.log.warn("guest login disabled: {}", windowsIdentity.getFqn());
                 this.sendUnauthorized(response);
                 return false;
             }
 
             try {
                 this.log.debug("logged in user: {} ({})", windowsIdentity.getFqn(), windowsIdentity.getSidString());
 
                 final GenericWindowsPrincipal windowsPrincipal = new GenericWindowsPrincipal(windowsIdentity,
                         this.principalFormat, this.roleFormat);
 
                 this.log.debug("roles: {}", windowsPrincipal.getRolesString());
 
                 principal = windowsPrincipal;
 
                 // create a session associated with this request if there's none
                 final HttpSession session = request.getSession(true);
                 this.log.debug("session id: {}", session == null ? "null" : session.getId());
 
                 // register the authenticated principal
                 this.register(request, response, principal, securityPackage, principal.getName(), null);
                 this.log.info("successfully logged in user: {}", principal.getName());
 
             } finally {
                 windowsIdentity.dispose();
             }
 
             return true;
         }
 
         this.log.debug("authorization required");
         this.sendUnauthorized(response);
         return false;
     }
 }