#if MYSQL_6_10

// Copyright ?2012, 2018, Oracle and/or its affiliates. All rights reserved.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
// MySQL Connectors. There are special exceptions to the terms and 
// conditions of the GPLv2 as it is applied to this software, see the 
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published 
// by the Free Software Foundation; version 2 of the License.
//
// 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 
// 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

using System;
using System.Security.Cryptography;

namespace Externals.MySql.Data.MySqlClient.Authentication
{
    /// <summary>
    /// Allows connections to a user account set with the mysql_native_password authentication plugin.
    /// </summary>
    internal class MySqlNativePasswordPlugin : MySqlAuthenticationPlugin
    {
        public override string PluginName => "mysql_native_password";

        protected override void SetAuthData(byte[] data)
        {
            // if the data given to us is a null terminated string, we need to trim off the trailing zero
            if (data[data.Length - 1] == 0)
            {
                byte[] b = new byte[data.Length - 1];
                Buffer.BlockCopy(data, 0, b, 0, data.Length - 1);
                base.SetAuthData(b);
            }
            else
                base.SetAuthData(data);
        }

        protected override byte[] MoreData(byte[] data)
        {
            byte[] passBytes = (GetPassword() ?? new byte[1]) as byte[];
            byte[] buffer = new byte[passBytes.Length - 1];
            Array.Copy(passBytes, 1, buffer, 0, passBytes.Length - 1);
            return buffer;
        }

        public override object GetPassword()
        {
            byte[] bytes = Get411Password(Settings.Password, AuthenticationData);
            if (bytes != null && bytes.Length == 1 && bytes[0] == 0) return null;
            return bytes;
        }

        /// <summary>
        /// Returns a byte array containing the proper encryption of the 
        /// given password/seed according to the new 4.1.1 authentication scheme.
        /// </summary>
        /// <param name="password"></param>
        /// <param name="seedBytes"></param>
        /// <returns></returns>
        protected byte[] Get411Password(string password, byte[] seedBytes)
        {
            // if we have no password, then we just return 1 zero byte
            if (password.Length == 0) return new byte[1];
            //SHA1 sha = new SHA1CryptoServiceProvider();
            SHA1 sha = SHA1.Create();

            byte[] firstHash = sha.ComputeHash(this.Encoding.GetBytes(password));
            byte[] secondHash = sha.ComputeHash(firstHash);

            byte[] input = new byte[seedBytes.Length + secondHash.Length];
            Array.Copy(seedBytes, 0, input, 0, seedBytes.Length);
            Array.Copy(secondHash, 0, input, seedBytes.Length, secondHash.Length);
            byte[] thirdHash = sha.ComputeHash(input);

            byte[] finalHash = new byte[thirdHash.Length + 1];
            finalHash[0] = 0x14;
            Array.Copy(thirdHash, 0, finalHash, 1, thirdHash.Length);

            for (int i = 1; i < finalHash.Length; i++)
                finalHash[i] = (byte)(finalHash[i] ^ firstHash[i - 1]);
            return finalHash;
        }
    }
}

#endif