content: /**
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.aurora.scheduler.http.api.security;
  
  import java.io.IOException;
  import java.util.Optional;
  
  import javax.inject.Inject;
  import javax.inject.Provider;
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.ws.rs.core.HttpHeaders;
  
  import org.apache.aurora.scheduler.http.AbstractFilter;
  import org.apache.shiro.authc.AuthenticationException;
  import org.apache.shiro.subject.Subject;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static java.util.Objects.requireNonNull;
  
  public class ShiroKerberosAuthenticationFilter extends AbstractFilter {
    private static final Logger LOG =
        LoggerFactory.getLogger(ShiroKerberosAuthenticationFilter.class);
  
    /**
     * From http://tools.ietf.org/html/rfc4559.
     */
    public static final String NEGOTIATE = "Negotiate";
  
    private final Provider<Subject> subjectProvider;
  
    @Inject
    ShiroKerberosAuthenticationFilter(Provider<Subject> subjectProvider) {
      this.subjectProvider = requireNonNull(subjectProvider);
    }
  
    @Override
    protected void doFilter(
        HttpServletRequest request,
        HttpServletResponse response,
        FilterChain chain) throws IOException, ServletException {
  
      Optional<String> authorizationHeaderValue =
          Optional.ofNullable(request.getHeader(HttpHeaders.AUTHORIZATION));
      if (authorizationHeaderValue.isPresent()) {
        LOG.debug("Authorization header is present");
        AuthorizeHeaderToken token;
        try {
          token = new AuthorizeHeaderToken(authorizationHeaderValue.get());
        } catch (IllegalArgumentException e) {
          LOG.info("Malformed Authorize header: " + e.getMessage());
          response.sendError(HttpServletResponse.SC_BAD_REQUEST);
          return;
        }
        try {
          subjectProvider.get().login(token);
          chain.doFilter(request, response);
        } catch (AuthenticationException e) {
          LOG.warn("Login failed: " + e.getMessage());
          sendChallenge(response);
        }
      } else {
        handleUnauthenticated(request, response, chain);
      }
    }
  
    protected void handleUnauthenticated(
        HttpServletRequest request,
        HttpServletResponse response,
        FilterChain chain) throws IOException, ServletException {
  
      sendChallenge(response);
    }
  
    private void sendChallenge(HttpServletResponse response) throws IOException {
      response.setHeader(HttpHeaders.WWW_AUTHENTICATE, NEGOTIATE);
      response.sendError(HttpServletResponse.SC_UNAUTHORIZED);
    }
  }
  