/*
 * 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 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 javax.security.sasl.Sasl;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.ipc.RpcServer;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.SecretManager;
import org.apache.hadoop.security.token.TokenIdentifier;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;

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

  public static enum QualityOfProtection {
    AUTHENTICATION("auth"),
    INTEGRITY("auth-int"),
    PRIVACY("auth-conf");

    public final String saslQop;

    private QualityOfProtection(String saslQop) {
      this.saslQop = saslQop;
    }

    public String getSaslQop() {
      return saslQop;
    }
  }

  public static void init(Configuration conf) {
    QualityOfProtection saslQOP = QualityOfProtection.AUTHENTICATION;
    String rpcProtection = conf.get("hbase.rpc.protection",
        QualityOfProtection.AUTHENTICATION.name().toLowerCase());
    if (QualityOfProtection.INTEGRITY.name().toLowerCase()
        .equals(rpcProtection)) {
      saslQOP = QualityOfProtection.INTEGRITY;
    } else if (QualityOfProtection.PRIVACY.name().toLowerCase().equals(
        rpcProtection)) {
      saslQOP = QualityOfProtection.PRIVACY;
    }

    SaslUtil.SASL_PROPS.put(Sasl.QOP, saslQOP.getSaslQop());
    SaslUtil.SASL_PROPS.put(Sasl.SERVER_AUTH, "true");
  }

  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 RpcServer.Connection connection;

    public SaslDigestCallbackHandler(
        SecretManager<TokenIdentifier> secretManager,
        RpcServer.Connection connection) {
      this.secretManager = secretManager;
      this.connection = connection;
    }

    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 = null;
        user = tokenIdentifier.getUser(); // may throw exception
        connection.attemptingUser = user;
        if (LOG.isDebugEnabled()) {
          LOG.debug("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.isDebugEnabled()) {
            String username =
              getIdentifier(authzid, secretManager).getUser().getUserName();
            LOG.debug("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);
        }
      }
    }
  }
}
