/*
    * MIT License
    *
    * Copyright (c) 2010-2024 The Waffle Project Contributors: https://github.com/Waffle/waffle/graphs/contributors
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy
    * of this software and associated documentation files (the "Software"), to deal
    * in the Software without restriction, including without limitation the rights
    * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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   * SOFTWARE.
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  package waffle.shiro.negotiate;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Base64;
  import java.util.List;
  import java.util.Locale;
  
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.shiro.authc.AuthenticationException;
  import org.apache.shiro.authc.AuthenticationToken;
  import org.apache.shiro.subject.Subject;
  import org.apache.shiro.web.filter.authc.AuthenticatingFilter;
  import org.apache.shiro.web.filter.authc.FormAuthenticationFilter;
  import org.apache.shiro.web.util.WebUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import waffle.util.AuthorizationHeader;
  import waffle.util.NtlmServletRequest;
  
  /**
   * A authentication filter that implements the HTTP Negotiate mechanism. The current user is authenticated, providing
   * single-sign-on. Derived from net.skorgenes.security.jsecurity.negotiate.NegotiateAuthenticationFilter. see:
   * https://bitbucket.org/lothor
   * /shiro-negotiate/src/7b25efde130b9cbcacf579b3f926c532d919aa23/src/main/java/net/skorgenes/
   * security/jsecurity/negotiate/NegotiateAuthenticationFilter.java?at=default
   *
   * @since 1.0.0
   */
  public class NegotiateAuthenticationFilter extends AuthenticatingFilter {
  
      /**
       * This class's private logger.
       */
      private static final Logger LOGGER = LoggerFactory.getLogger(NegotiateAuthenticationFilter.class);
  
      // TODO things (sometimes) break, depending on what user account is running tomcat:
      // related to setSPN and running tomcat server as NT Service account vs. as normal user account.
      // https://waffle.codeplex.com/discussions/254748
      // setspn -A HTTP/<server-fqdn> <user_tomcat_running_under>
      /** The Constant PROTOCOLS. */
      private static final List<String> PROTOCOLS = new ArrayList<>();
  
      /** The failure key attribute. */
      private String failureKeyAttribute = FormAuthenticationFilter.DEFAULT_ERROR_KEY_ATTRIBUTE_NAME;
  
      /** The remember me param. */
      private String rememberMeParam = FormAuthenticationFilter.DEFAULT_REMEMBER_ME_PARAM;
  
      /**
       * Instantiates a new negotiate authentication filter.
       */
      public NegotiateAuthenticationFilter() {
          NegotiateAuthenticationFilter.PROTOCOLS.add("Negotiate");
          NegotiateAuthenticationFilter.PROTOCOLS.add("NTLM");
      }
  
      /**
       * Gets the remember me param.
       *
       * @return the remember me param
       */
      public String getRememberMeParam() {
          return this.rememberMeParam;
      }
  
      /**
       * Sets the request parameter name to look for when acquiring the rememberMe boolean value. Unless overridden by
       * calling this method, the default is <code>rememberMe</code>. <br>
       * <br>
       * RememberMe will be <code>true</code> if the parameter value equals any of those supported by
      * {@link org.apache.shiro.web.util.WebUtils#isTrue(javax.servlet.ServletRequest, String)
      * WebUtils.isTrue(request,value)}, <code>false</code> otherwise.
      *
      * @param value
      *            the name of the request param to check for acquiring the rememberMe boolean value.
      */
     public void setRememberMeParam(final String value) {
         this.rememberMeParam = value;
     }
 
     @Override
     protected boolean isRememberMe(final ServletRequest request) {
         return WebUtils.isTrue(request, this.getRememberMeParam());
     }
 
     @Override
     protected AuthenticationToken createToken(final ServletRequest request, final ServletResponse response) {
         final String authorization = this.getAuthzHeader(request);
         final String[] elements = authorization.split(" ", -1);
         final byte[] inToken = Base64.getDecoder().decode(elements[1]);
 
         // maintain a connection-based session for NTLM tokens
         // TODO see about changing this parameter to ServletRequest in waffle
         final String connectionId = NtlmServletRequest.getConnectionId((HttpServletRequest) request);
         final String securityPackage = elements[0];
 
         // TODO see about changing this parameter to ServletRequest in waffle
         final AuthorizationHeader authorizationHeader = new AuthorizationHeader((HttpServletRequest) request);
         final boolean ntlmPost = authorizationHeader.isNtlmType1PostAuthorizationHeader();
 
         NegotiateAuthenticationFilter.LOGGER.debug("security package: {}, connection id: {}, ntlmPost: {}",
                 securityPackage, connectionId, Boolean.valueOf(ntlmPost));
 
         final boolean rememberMe = this.isRememberMe(request);
         final String host = this.getHost(request);
 
         return new NegotiateToken(inToken, new byte[0], connectionId, securityPackage, ntlmPost, rememberMe, host);
     }
 
     @Override
     protected boolean onLoginSuccess(final AuthenticationToken token, final Subject subject,
             final ServletRequest request, final ServletResponse response) throws Exception {
         request.setAttribute("MY_SUBJECT", ((NegotiateToken) token).getSubject());
         return true;
     }
 
     @Override
     protected boolean onLoginFailure(final AuthenticationToken token, final AuthenticationException e,
             final ServletRequest request, final ServletResponse response) {
         if (e instanceof AuthenticationInProgressException) {
             // negotiate is processing
             final String protocol = this.getAuthzHeaderProtocol(request);
             NegotiateAuthenticationFilter.LOGGER.debug("Negotiation in progress for protocol: {}", protocol);
             this.sendChallengeDuringNegotiate(protocol, response, ((NegotiateToken) token).getOut());
             return false;
         }
         NegotiateAuthenticationFilter.LOGGER.warn("login exception: {}", e.getMessage());
 
         // do not send token.out bytes, this was a login failure.
         this.sendChallengeOnFailure(response);
 
         this.setFailureAttribute(request, e);
         return true;
     }
 
     /**
      * Sets the failure attribute.
      *
      * @param request
      *            the request
      * @param ae
      *            the ae
      */
     protected void setFailureAttribute(final ServletRequest request, final AuthenticationException ae) {
         final String className = ae.getClass().getName();
         request.setAttribute(this.getFailureKeyAttribute(), className);
     }
 
     /**
      * Gets the failure key attribute.
      *
      * @return the failure key attribute
      */
     public String getFailureKeyAttribute() {
         return this.failureKeyAttribute;
     }
 
     /**
      * Sets the failure key attribute.
      *
      * @param value
      *            the new failure key attribute
      */
     public void setFailureKeyAttribute(final String value) {
         this.failureKeyAttribute = value;
     }
 
     @Override
     protected boolean onAccessDenied(final ServletRequest request, final ServletResponse response) throws Exception {
         // false by default or we wouldn't be in
         boolean loggedIn = false;
         // this method
         if (this.isLoginAttempt(request)) {
             loggedIn = this.executeLogin(request, response);
         } else {
             NegotiateAuthenticationFilter.LOGGER.debug("authorization required, supported protocols: {}",
                     NegotiateAuthenticationFilter.PROTOCOLS);
             this.sendChallengeInitiateNegotiate(response);
         }
         return loggedIn;
     }
 
     /**
      * Returns the {@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter#AUTHORIZATION_HEADER
      * AUTHORIZATION_HEADER} from the specified ServletRequest.
      * <p/>
      * This implementation merely casts the request to an <code>HttpServletRequest</code> and returns the header:
      * <p/>
      * <code>HttpServletRequest httpRequest = {@link WebUtils#toHttp(javax.servlet.ServletRequest) toHttp(reaquest)};<br/>
      * return httpRequest.getHeader({@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter#AUTHORIZATION_HEADER AUTHORIZATION_HEADER});</code>
      *
      * @param request
      *            the incoming <code>ServletRequest</code>
      *
      * @return the <code>Authorization</code> header's value.
      */
     private String getAuthzHeader(final ServletRequest request) {
         final HttpServletRequest httpRequest = WebUtils.toHttp(request);
         return httpRequest.getHeader("Authorization");
     }
 
     /**
      * Gets the authz header protocol.
      *
      * @param request
      *            the request
      *
      * @return the authz header protocol
      */
     private String getAuthzHeaderProtocol(final ServletRequest request) {
         final String authzHeader = this.getAuthzHeader(request);
         return authzHeader.substring(0, authzHeader.indexOf(' '));
     }
 
     /**
      * Determines whether the incoming request is an attempt to log in.
      * <p/>
      * The default implementation obtains the value of the request's
      * {@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter#AUTHORIZATION_HEADER AUTHORIZATION_HEADER}
      * , and if it is not <code>null</code>, delegates to
      * {@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter#isLoginAttempt(String)
      * isLoginAttempt(authzHeaderValue)}. If the header is <code>null</code>, <code>false</code> is returned.
      *
      * @param request
      *            incoming ServletRequest
      *
      * @return true if the incoming request is an attempt to log in based, false otherwise
      */
     private boolean isLoginAttempt(final ServletRequest request) {
         final String authzHeader = this.getAuthzHeader(request);
         return authzHeader != null && this.isLoginAttempt(authzHeader);
     }
 
     /**
      * Default implementation that returns <code>true</code> if the specified <code>authzHeader</code> starts with the
      * same (case-insensitive) characters specified by any of the configured protocols (Negotiate or NTLM),
      * <code>false</code> otherwise.
      *
      * @param authzHeader
      *            the 'Authorization' header value (guaranteed to be non-null if the
      *            {@link #isLoginAttempt(javax.servlet.ServletRequest)} method is not overriden).
      *
      * @return <code>true</code> if the authzHeader value matches any of the configured protocols (Negotiate or NTLM).
      */
     boolean isLoginAttempt(final String authzHeader) {
         for (final String protocol : NegotiateAuthenticationFilter.PROTOCOLS) {
             if (authzHeader.toLowerCase(Locale.ENGLISH).startsWith(protocol.toLowerCase(Locale.ENGLISH))) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Builds the challenge for authorization by setting a HTTP <code>401</code> (Unauthorized) status as well as the
      * response's {@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter#AUTHENTICATE_HEADER
      * AUTHENTICATE_HEADER}.
      *
      * @param protocols
      *            protocols for which to send a challenge. In initial cases, will be all supported protocols. In the
      *            midst of negotiation, will be only the protocol being negotiated.
      * @param response
      *            outgoing ServletResponse
      * @param out
      *            token.out or null
      */
     private void sendChallenge(final List<String> protocols, final ServletResponse response, final byte[] out) {
         final HttpServletResponse httpResponse = WebUtils.toHttp(response);
         this.sendAuthenticateHeader(protocols, out, httpResponse);
         httpResponse.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
     }
 
     /**
      * Send challenge initiate negotiate.
      *
      * @param response
      *            the response
      */
     void sendChallengeInitiateNegotiate(final ServletResponse response) {
         this.sendChallenge(NegotiateAuthenticationFilter.PROTOCOLS, response, null);
     }
 
     /**
      * Send challenge during negotiate.
      *
      * @param protocol
      *            the protocol
      * @param response
      *            the response
      * @param out
      *            the out
      */
     void sendChallengeDuringNegotiate(final String protocol, final ServletResponse response, final byte[] out) {
         final List<String> protocolsList = new ArrayList<>();
         protocolsList.add(protocol);
         this.sendChallenge(protocolsList, response, out);
     }
 
     /**
      * Send challenge on failure.
      *
      * @param response
      *            the response
      */
     void sendChallengeOnFailure(final ServletResponse response) {
         final HttpServletResponse httpResponse = WebUtils.toHttp(response);
         this.sendUnauthorized(NegotiateAuthenticationFilter.PROTOCOLS, null, httpResponse);
         httpResponse.setHeader("Connection", "close");
         try {
             httpResponse.sendError(HttpServletResponse.SC_UNAUTHORIZED);
             httpResponse.flushBuffer();
         } catch (final IOException e) {
             throw new RuntimeException(e);
         }
     }
 
     /**
      * Send authenticate header.
      *
      * @param protocolsList
      *            the protocols list
      * @param out
      *            the out
      * @param httpResponse
      *            the http response
      */
     private void sendAuthenticateHeader(final List<String> protocolsList, final byte[] out,
             final HttpServletResponse httpResponse) {
         this.sendUnauthorized(protocolsList, out, httpResponse);
         httpResponse.setHeader("Connection", "keep-alive");
     }
 
     /**
      * Send unauthorized.
      *
      * @param protocols
      *            the protocols
      * @param out
      *            the out
      * @param response
      *            the response
      */
     private void sendUnauthorized(final List<String> protocols, final byte[] out, final HttpServletResponse response) {
         for (final String protocol : protocols) {
             if (out == null || out.length == 0) {
                 response.addHeader("WWW-Authenticate", protocol);
             } else {
                 response.setHeader("WWW-Authenticate", protocol + " " + Base64.getEncoder().encodeToString(out));
             }
         }
     }
 
 }