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.kafka.common.security.kerberos;
  
  import org.apache.kafka.common.KafkaException;
  import org.apache.kafka.common.security.authenticator.SaslClientAuthenticator;
  import org.apache.kafka.common.utils.Java;
  
  import org.ietf.jgss.GSSException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.lang.reflect.Method;
  
  import javax.security.sasl.SaslClient;
  
  /**
   * Kerberos exceptions that may require special handling. The standard Kerberos error codes
   * for these errors are retrieved using KrbException#errorCode() from the underlying Kerberos
   * exception thrown during {@link SaslClient#evaluateChallenge(byte[])}.
   */
  public enum KerberosError {
      // (Mechanism level: Server not found in Kerberos database (7) - UNKNOWN_SERVER)
      // This is retriable, but included here to add extra logging for this case.
      SERVER_NOT_FOUND(7, false),
      // (Mechanism level: Client not yet valid - try again later (21))
      CLIENT_NOT_YET_VALID(21, true),
      // (Mechanism level: Ticket not yet valid (33) - Ticket not yet valid)])
      // This could be a small timing window.
      TICKET_NOT_YET_VALID(33, true),
      // (Mechanism level: Request is a replay (34) - Request is a replay)
      // Replay detection used to prevent DoS attacks can result in false positives, so retry on error.
      REPLAY(34, true);
  
      private static final Logger log = LoggerFactory.getLogger(SaslClientAuthenticator.class);
      private static final Class<?> KRB_EXCEPTION_CLASS;
      private static final Method KRB_EXCEPTION_RETURN_CODE_METHOD;
  
      static {
          try {
              // different IBM JDKs versions include different security implementations
              if (Java.isIbmJdk() && canLoad("com.ibm.security.krb5.KrbException")) {
                  KRB_EXCEPTION_CLASS = Class.forName("com.ibm.security.krb5.KrbException");
              } else if (Java.isIbmJdk() && canLoad("com.ibm.security.krb5.internal.KrbException")) {
                  KRB_EXCEPTION_CLASS = Class.forName("com.ibm.security.krb5.internal.KrbException");
              } else {
                  KRB_EXCEPTION_CLASS = Class.forName("sun.security.krb5.KrbException");
              }
              KRB_EXCEPTION_RETURN_CODE_METHOD = KRB_EXCEPTION_CLASS.getMethod("returnCode");
          } catch (Exception e) {
              throw new KafkaException("Kerberos exceptions could not be initialized", e);
          }
      }
  
      private static boolean canLoad(String clazz) {
          try {
              Class.forName(clazz);
              return true;
          } catch (Exception e) {
              return false;
          }
      }
  
      private final int errorCode;
      private final boolean retriable;
  
      KerberosError(int errorCode, boolean retriable) {
          this.errorCode = errorCode;
          this.retriable = retriable;
      }
  
      public boolean retriable() {
          return retriable;
      }
  
      public static KerberosError fromException(Exception exception) {
          Throwable cause = exception.getCause();
          while (cause != null && !KRB_EXCEPTION_CLASS.isInstance(cause)) {
              cause = cause.getCause();
          }
          if (cause == null)
              return null;
          else {
              try {
                  Integer errorCode = (Integer) KRB_EXCEPTION_RETURN_CODE_METHOD.invoke(cause);
                  return fromErrorCode(errorCode);
              } catch (Exception e) {
                  log.trace("Kerberos return code could not be determined from {}", exception, e);
                  return null;
              }
          }
      }
  
      private static KerberosError fromErrorCode(int errorCode) {
          for (KerberosError error : values()) {
              if (error.errorCode == errorCode)
                  return error;
          }
          return null;
      }
  
      /**
       * Returns true if the exception should be handled as a transient failure on clients.
       * We handle GSSException.NO_CRED as retriable on the client-side since this may
       * occur during re-login if a clients attempts to authentication after logout, but
       * before the subsequent login.
       */
      public static boolean isRetriableClientGssException(Exception exception) {
          Throwable cause = exception.getCause();
          while (cause != null && !(cause instanceof GSSException)) {
              cause = cause.getCause();
          }
          if (cause != null) {
              GSSException gssException = (GSSException) cause;
              return gssException.getMajor() == GSSException.NO_CRED;
          }
          return false;
      }
  }
  