/*
 * 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.hadoop.hbase.security;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.Locale;
import java.util.Map;
import java.util.function.Consumer;

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.AuthorizeCallback;
import javax.security.sasl.RealmCallback;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.security.SaslUtil.QualityOfProtection;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.SecretManager;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.TokenIdentifier;

/**
 * A utility class for dealing with SASL on RPC server
 */
@InterfaceAudience.Private
public class HBaseSaslRpcServer {
  private static final Log LOG = LogFactory.getLog(HBaseSaslRpcServer.class);

  private static Map<String, String> saslProps = null;

  public static void init(Configuration conf) {
    saslProps = SaslUtil.initSaslProperties(conf.get("hbase.rpc.protection",
          QualityOfProtection.AUTHENTICATION.name().toLowerCase(Locale.ROOT)));
  }

  public static Map<String, String> getSaslProps() {
    return saslProps;
  }

  public static <T extends TokenIdentifier> T getIdentifier(String id,
      SecretManager<T> secretManager) throws InvalidToken {
    byte[] tokenId = SaslUtil.decodeIdentifier(id);
    T tokenIdentifier = secretManager.createIdentifier();
    try {
      tokenIdentifier.readFields(new DataInputStream(new ByteArrayInputStream(
          tokenId)));
    } catch (IOException e) {
      throw (InvalidToken) new InvalidToken(
          "Can't de-serialize tokenIdentifier").initCause(e);
    }
    return tokenIdentifier;
  }


  /** CallbackHandler for SASL DIGEST-MD5 mechanism */
  public static class SaslDigestCallbackHandler implements CallbackHandler {
    private SecretManager<TokenIdentifier> secretManager;
    private Consumer<UserGroupInformation> attemptingUserConsumer;

    public SaslDigestCallbackHandler(SecretManager<TokenIdentifier> secretManager,
        Consumer<UserGroupInformation> attemptingUserConsumer) {
      this.secretManager = secretManager;
      this.attemptingUserConsumer = attemptingUserConsumer;
    }

    private char[] getPassword(TokenIdentifier tokenid) throws InvalidToken {
      return SaslUtil.encodePassword(secretManager.retrievePassword(tokenid));
    }

    /** {@inheritDoc} */
    @Override
    public void handle(Callback[] callbacks) throws InvalidToken,
        UnsupportedCallbackException {
      NameCallback nc = null;
      PasswordCallback pc = null;
      AuthorizeCallback ac = null;
      for (Callback callback : callbacks) {
        if (callback instanceof AuthorizeCallback) {
          ac = (AuthorizeCallback) callback;
        } else if (callback instanceof NameCallback) {
          nc = (NameCallback) callback;
        } else if (callback instanceof PasswordCallback) {
          pc = (PasswordCallback) callback;
        } else if (callback instanceof RealmCallback) {
          continue; // realm is ignored
        } else {
          throw new UnsupportedCallbackException(callback,
              "Unrecognized SASL DIGEST-MD5 Callback");
        }
      }
      if (pc != null) {
        TokenIdentifier tokenIdentifier = getIdentifier(nc.getDefaultName(), secretManager);
        char[] password = getPassword(tokenIdentifier);
        UserGroupInformation user = tokenIdentifier.getUser(); // may throw exception
        attemptingUserConsumer.accept(user);
        if (LOG.isTraceEnabled()) {
          LOG.trace("SASL server DIGEST-MD5 callback: setting password " + "for client: " +
              tokenIdentifier.getUser());
        }
        pc.setPassword(password);
      }
      if (ac != null) {
        String authid = ac.getAuthenticationID();
        String authzid = ac.getAuthorizationID();
        if (authid.equals(authzid)) {
          ac.setAuthorized(true);
        } else {
          ac.setAuthorized(false);
        }
        if (ac.isAuthorized()) {
          if (LOG.isTraceEnabled()) {
            String username =
              getIdentifier(authzid, secretManager).getUser().getUserName();
            LOG.trace("SASL server DIGEST-MD5 callback: setting "
                + "canonicalized client ID: " + username);
          }
          ac.setAuthorizedID(authzid);
        }
      }
    }
  }

  /** CallbackHandler for SASL GSSAPI Kerberos mechanism */
  public static class SaslGssCallbackHandler implements CallbackHandler {

    /** {@inheritDoc} */
    @Override
    public void handle(Callback[] callbacks) throws
        UnsupportedCallbackException {
      AuthorizeCallback ac = null;
      for (Callback callback : callbacks) {
        if (callback instanceof AuthorizeCallback) {
          ac = (AuthorizeCallback) callback;
        } else {
          throw new UnsupportedCallbackException(callback,
              "Unrecognized SASL GSSAPI Callback");
        }
      }
      if (ac != null) {
        String authid = ac.getAuthenticationID();
        String authzid = ac.getAuthorizationID();
        if (authid.equals(authzid)) {
          ac.setAuthorized(true);
        } else {
          ac.setAuthorized(false);
        }
        if (ac.isAuthorized()) {
          if (LOG.isDebugEnabled())
            LOG.debug("SASL server GSSAPI callback: setting "
                + "canonicalized client ID: " + authzid);
          ac.setAuthorizedID(authzid);
        }
      }
    }
  }
}