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.scram.internals;
  
  import org.apache.kafka.common.security.auth.AuthenticateCallbackHandler;
  import org.apache.kafka.common.security.authenticator.CredentialCache;
  import org.apache.kafka.common.security.scram.ScramCredential;
  import org.apache.kafka.common.security.scram.ScramCredentialCallback;
  import org.apache.kafka.common.security.token.delegation.TokenInformation;
  import org.apache.kafka.common.security.token.delegation.internals.DelegationTokenCache;
  import org.apache.kafka.common.security.token.delegation.internals.DelegationTokenCredentialCallback;
  
  import java.util.List;
  import java.util.Map;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.auth.login.AppConfigurationEntry;
  
  public class ScramServerCallbackHandler implements AuthenticateCallbackHandler {
  
      private final CredentialCache.Cache<ScramCredential> credentialCache;
      private final DelegationTokenCache tokenCache;
      private String saslMechanism;
  
      public ScramServerCallbackHandler(CredentialCache.Cache<ScramCredential> credentialCache,
                                        DelegationTokenCache tokenCache) {
          this.credentialCache = credentialCache;
          this.tokenCache = tokenCache;
      }
  
      @Override
      public void configure(Map<String, ?> configs, String mechanism, List<AppConfigurationEntry> jaasConfigEntries) {
          this.saslMechanism = mechanism;
      }
  
      @Override
      public void handle(Callback[] callbacks) throws UnsupportedCallbackException {
          String username = null;
          for (Callback callback : callbacks) {
              if (callback instanceof NameCallback)
                  username = ((NameCallback) callback).getDefaultName();
              else if (callback instanceof DelegationTokenCredentialCallback) {
                  DelegationTokenCredentialCallback tokenCallback = (DelegationTokenCredentialCallback) callback;
                  tokenCallback.scramCredential(tokenCache.credential(saslMechanism, username));
                  tokenCallback.tokenOwner(tokenCache.owner(username));
                  TokenInformation tokenInfo = tokenCache.token(username);
                  if (tokenInfo != null)
                      tokenCallback.tokenExpiryTimestamp(tokenInfo.expiryTimestamp());
              } else if (callback instanceof ScramCredentialCallback) {
                  ScramCredentialCallback sc = (ScramCredentialCallback) callback;
                  sc.scramCredential(credentialCache.get(username));
              } else
                  throw new UnsupportedCallbackException(callback);
          }
      }
  
      @Override
      public void close() {
      }
  }
  