content: /*
   * Copyright (c) 2020, Oracle and/or its affiliates.
   *
   * This program is free software; you can redistribute it and/or modify it under
   * the terms of the GNU General Public License, version 2.0, as published by the
   * Free Software Foundation.
   *
   * This program is also distributed with certain software (including but not
   * limited to OpenSSL) that is licensed under separate terms, as designated in a
   * particular file or component or in included license documentation. The
   * authors of MySQL hereby grant you an additional permission to link the
   * program and your derivative works with the separately licensed software that
   * they have included with MySQL.
   *
   * Without limiting anything contained in the foregoing, this file, which is
   * part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
   * version 1.0, a copy of which can be found at
   * http://oss.oracle.com/licenses/universal-foss-exception.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
   * FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
   * for more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc.,
   * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
   */
  
  package com.mysql.cj.sasl;
  
  import java.io.IOException;
  import java.util.Map;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.PasswordCallback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.sasl.SaslClient;
  import javax.security.sasl.SaslClientFactory;
  import javax.security.sasl.SaslException;
  
  import com.mysql.cj.util.StringUtils;
  
  /**
   * A {@link SaslClientFactory} for {@link ScramSha1SaslClient} and {@link ScramSha256SaslClient} instances.
   */
  public class ScramShaSaslClientFactory implements SaslClientFactory {
      private static final String[] SUPPORTED_MECHANISMS = { ScramSha1SaslClient.MECHANISM_NAME, ScramSha256SaslClient.MECHANISM_NAME };
  
      @Override
      public SaslClient createSaslClient(String[] mechanisms, String authorizationId, String protocol, String serverName, Map<String, ?> props,
              CallbackHandler cbh) throws SaslException {
          for (String mech : mechanisms) {
              if (mech.equals(ScramSha1SaslClient.MECHANISM_NAME)) {
                  return new ScramSha1SaslClient(authorizationId, getUsername(mech, authorizationId, cbh), getPassword(mech, cbh));
              }
              if (mech.equals(ScramSha256SaslClient.MECHANISM_NAME)) {
                  return new ScramSha256SaslClient(authorizationId, getUsername(mech, authorizationId, cbh), getPassword(mech, cbh));
              }
          }
          return null;
      }
  
      @Override
      public String[] getMechanismNames(Map<String, ?> props) {
          return SUPPORTED_MECHANISMS.clone();
      }
  
      /**
       * Gets the authentication id, which is provided by a {@link CallbackHandler} to be implemented by the requester of this service.
       * 
       * @param prefix
       *            the prefix to use in the prompt.
       * @param authorizationId
       *            the authorization id that can be used as default authentication id if none is provided.
       * @param cbh
       *            the callback handler to use.
       * @return
       *         an authentication id
       * @throws SaslException
       *             if the callback handler is null or not supported by the callback handler implementer.
       */
      private String getUsername(String prefix, String authorizationId, CallbackHandler cbh) throws SaslException {
          if (cbh == null) {
              throw new SaslException("Callback handler required to get username.");
          }
  
          try {
              String prompt = prefix + " authentication id:";
              NameCallback ncb = StringUtils.isNullOrEmpty(authorizationId) ? new NameCallback(prompt) : new NameCallback(prompt, authorizationId);
              cbh.handle(new Callback[] { ncb });
  
              String userName = ncb.getName();
              return userName;
          } catch (IOException | UnsupportedCallbackException e) {
              throw new SaslException("Cannot get username", e);
          }
      }
  
      /**
       * Gets the password, which is provided by a {@link CallbackHandler} to be implemented by the requester of this service.
       * 
       * @param prefix
       *            the prefix to use in the prompt.
       * @param cbh
       *            the callback handler to use.
       * @return
       *         a password
       * @throws SaslException
       *             if the callback handler is null or not supported by the callback handler implementer.
       */
      private String getPassword(String prefix, CallbackHandler cbh) throws SaslException {
          if (cbh == null) {
              throw new SaslException("Callback handler required to get password.");
          }
  
          try {
              String prompt = prefix + " password:";
              PasswordCallback pcb = new PasswordCallback(prompt, false);
              cbh.handle(new Callback[] { pcb });
  
              String password = new String(pcb.getPassword());
              pcb.clearPassword();
              return password;
          } catch (IOException | UnsupportedCallbackException e) {
              throw new SaslException("Cannot get password", e);
          }
      }
  }
  