/*
 *
 * MariaDB Client for Java
 *
 * Copyright (c) 2012-2014 Monty Program Ab.
 * Copyright (c) 2015-2020 MariaDB Corporation Ab.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with this library; if not, write to Monty Program Ab info@montyprogram.com.
 *
 * This particular MariaDB Client for Java file is work
 * derived from a Drizzle-JDBC. Drizzle-JDBC file which is covered by subject to
 * the following copyright and notice provisions:
 *
 * Copyright (c) 2009-2011, Marcus Eriksson
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or
 * other materials provided with the distribution.
 *
 * Neither the name of the driver nor the names of its contributors may not be
 * used to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS  AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 */

package org.mariadb.jdbc.internal.com.send.authentication.gssapi;

import java.io.*;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.sql.SQLException;
import java.util.concurrent.atomic.AtomicInteger;
import javax.security.auth.Subject;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import org.ietf.jgss.*;
import org.mariadb.jdbc.internal.com.read.Buffer;
import org.mariadb.jdbc.internal.io.input.PacketInputStream;
import org.mariadb.jdbc.internal.io.output.PacketOutputStream;

public class StandardGssapiAuthentication implements GssapiAuth {

  /**
   * Process default GSS plugin authentication.
   *
   * @param out out stream
   * @param in in stream
   * @param sequence packet sequence
   * @param servicePrincipalName service principal name
   * @param mechanisms gssapi mechanism
   * @throws IOException if socket error
   * @throws SQLException in any Exception occur
   */
  public void authenticate(
      final PacketOutputStream out,
      final PacketInputStream in,
      final AtomicInteger sequence,
      final String servicePrincipalName,
      String mechanisms)
      throws SQLException, IOException {

    if ("".equals(servicePrincipalName)) {
      throw new SQLException(
          "No principal name defined on server. "
              + "Please set server variable \"gssapi-principal-name\" or set option \"servicePrincipalName\"",
          "28000");
    }

    if (System.getProperty("java.security.auth.login.config") == null) {
      final File jaasConfFile;
      try {
        jaasConfFile = File.createTempFile("jaas.conf", null);
        try (PrintStream bos = new PrintStream(new FileOutputStream(jaasConfFile))) {
          bos.print(
              "Krb5ConnectorContext {\n"
                  + "com.sun.security.auth.module.Krb5LoginModule required "
                  + "useTicketCache=true "
                  + "debug=true "
                  + "renewTGT=true "
                  + "doNotPrompt=true; };");
        }
        jaasConfFile.deleteOnExit();
      } catch (final IOException ex) {
        throw new UncheckedIOException(ex);
      }

      System.setProperty("java.security.auth.login.config", jaasConfFile.getCanonicalPath());
    }
    try {
      LoginContext loginContext = new LoginContext("Krb5ConnectorContext");
      // attempt authentication
      loginContext.login();
      final Subject mySubject = loginContext.getSubject();
      if (!mySubject.getPrincipals().isEmpty()) {
        try {
          PrivilegedExceptionAction<Void> action =
              () -> {
                try {
                  Oid krb5Mechanism = new Oid("1.2.840.113554.1.2.2");

                  GSSManager manager = GSSManager.getInstance();
                  GSSName peerName = manager.createName(servicePrincipalName, GSSName.NT_USER_NAME);
                  GSSContext context =
                      manager.createContext(
                          peerName, krb5Mechanism, null, GSSContext.DEFAULT_LIFETIME);
                  context.requestMutualAuth(true);

                  byte[] inToken = new byte[0];
                  byte[] outToken;
                  while (true) {

                    outToken = context.initSecContext(inToken, 0, inToken.length);

                    // Send a token to the peer if one was generated by acceptSecContext
                    if (outToken != null && outToken.length > 0) {
                      out.startPacket(sequence.incrementAndGet());
                      out.write(outToken);
                      out.flush();
                    }
                    if (context.isEstablished()) {
                      break;
                    }
                    Buffer buffer = in.getPacket(true);
                    sequence.set(in.getLastPacketSeq());
                    inToken = buffer.readRawBytes(buffer.remaining());
                  }

                } catch (GSSException le) {
                  throw new SQLException("GSS-API authentication exception", "28000", 1045, le);
                }
                return null;
              };
          Subject.doAs(mySubject, action);
        } catch (PrivilegedActionException exception) {
          throw new SQLException("GSS-API authentication exception", "28000", 1045, exception);
        }
      } else {
        throw new SQLException(
            "GSS-API authentication exception : no credential cache not found.", "28000", 1045);
      }

    } catch (LoginException le) {
      throw new SQLException("GSS-API authentication exception", "28000", 1045, le);
    }
  }
}
