content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.cassandra.auth;
  
  import java.security.cert.Certificate;
  import java.security.cert.CertificateException;
  import java.security.cert.X509Certificate;
  import java.util.Collection;
  import java.util.List;
  
  import org.apache.cassandra.exceptions.AuthenticationException;
  
  import static org.apache.cassandra.auth.MutualTlsUtil.castCertsToX509;
  
  /**
   * This class assumes that the identity of a certificate is SPIFFE which is a URI that is present as part of the SAN
   * of the client certificate. It has logic to extract identity (Spiffe) out of a certificate & knows how to validate
   * the client certificates.
   *
   * <p>Example:
   * <pre>
   * internode_authenticator:
   *   class_name: org.apache.cassandra.auth.MutualTlsAuthenticator
   *   parameters:
   *     validator_class_name: org.apache.cassandra.auth.SpiffeCertificateValidator
   * </pre>
   *
   * <pre>
   * authenticator:
   *   class_name: org.apache.cassandra.auth.MutualTlsInternodeAuthenticator
   *   parameters:
   *     validator_class_name: org.apache.cassandra.auth.SpiffeCertificateValidator
   * </pre>
   */
  public class SpiffeCertificateValidator implements MutualTlsCertificateValidator
  {
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean isValidCertificate(Certificate[] clientCertificateChain)
      {
          return true;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public String identity(Certificate[] clientCertificateChain) throws AuthenticationException
      {
          // returns spiffe
          try
          {
              return getSANSpiffe(clientCertificateChain);
          }
          catch (CertificateException e)
          {
              throw new AuthenticationException(e.getMessage(), e);
          }
      }
  
      private static String getSANSpiffe(final Certificate[] clientCertificates) throws CertificateException
      {
          int URI_TYPE = 6;
          X509Certificate[] castedCerts = castCertsToX509(clientCertificates);
          Collection<List<?>> subjectAltNames = castedCerts[0].getSubjectAlternativeNames();
  
          if (subjectAltNames != null)
          {
              for (List<?> item : subjectAltNames)
              {
                  Integer type = (Integer) item.get(0);
                  String spiffe = (String) item.get(1);
                  if (type == URI_TYPE && spiffe.startsWith("spiffe://"))
                  {  // Spiffe is a URI
                      return spiffe;
                  }
              }
          }
          throw new CertificateException("Unable to extract Spiffe from the certificate");
      }
  }
  