jellyfin/Emby.Common.Implementations/IO/SharpCifs/Util/Base64.cs

// This code is derived from jcifs smb client library <jcifs at samba dot org>
// Ported by J. Arturo <webmaster at komodosoft dot net>
//  
// 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 the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
using System;
using System.Text;

namespace SharpCifs.Util
{
    public class Base64
    {
        private static readonly string Alphabet 
            = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

        /// <summary>Base-64 encodes the supplied block of data.</summary>
        /// <remarks>
        /// Base-64 encodes the supplied block of data.  Line wrapping is not
        /// applied on output.
        /// </remarks>
        /// <param name="bytes">The block of data that is to be Base-64 encoded.</param>
        /// <returns>A <code>String</code> containing the encoded data.</returns>
        public static string Encode(byte[] bytes)
        {
            int length = bytes.Length;
            if (length == 0)
            {
                return string.Empty;
            }
            StringBuilder buffer = new StringBuilder((int)Math.Ceiling(length / 3d) * 4);
            int remainder = length % 3;
            length -= remainder;
            int block;
            int i = 0;
            while (i < length)
            {
                block = ((bytes[i++] & unchecked(0xff)) << 16) | ((bytes[i++] & unchecked(
                    0xff)) << 8) | (bytes[i++] & unchecked(0xff));
                buffer.Append(Alphabet[(int)(((uint)block) >> 18)]);
                buffer.Append(Alphabet[((int)(((uint)block) >> 12)) & unchecked(0x3f)]);
                buffer.Append(Alphabet[((int)(((uint)block) >> 6)) & unchecked(0x3f)]);
                buffer.Append(Alphabet[block & unchecked(0x3f)]);
            }
            if (remainder == 0)
            {
                return buffer.ToString();
            }
            if (remainder == 1)
            {
                block = (bytes[i] & unchecked(0xff)) << 4;
                buffer.Append(Alphabet[(int)(((uint)block) >> 6)]);
                buffer.Append(Alphabet[block & unchecked(0x3f)]);
                buffer.Append("==");
                return buffer.ToString();
            }
            block = (((bytes[i++] & unchecked(0xff)) << 8) | ((bytes[i]) & unchecked(0xff))) << 2;
            buffer.Append(Alphabet[(int)(((uint)block) >> 12)]);
            buffer.Append(Alphabet[((int)(((uint)block) >> 6)) & unchecked(0x3f)]);
            buffer.Append(Alphabet[block & unchecked(0x3f)]);
            buffer.Append("=");
            return buffer.ToString();
        }

        /// <summary>Decodes the supplied Base-64 encoded string.</summary>
        /// <remarks>Decodes the supplied Base-64 encoded string.</remarks>
        /// <param name="string">The Base-64 encoded string that is to be decoded.</param>
        /// <returns>A <code>byte[]</code> containing the decoded data block.</returns>
        public static byte[] Decode(string @string)
        {
            int length = @string.Length;
            if (length == 0)
            {
                return new byte[0];
            }
            int pad = (@string[length - 2] == '=') ? 2 : (@string[length - 1] == '=') ? 1 : 0;
            int size = length * 3 / 4 - pad;
            byte[] buffer = new byte[size];
            int block;
            int i = 0;
            int index = 0;
            while (i < length)
            {
                block = (Alphabet.IndexOf(@string[i++]) & unchecked(0xff)) << 18 
                        | (Alphabet.IndexOf(@string[i++]) & unchecked(0xff)) << 12 
                        | (Alphabet.IndexOf(@string[i++]) & unchecked(0xff)) << 6 
                        | (Alphabet.IndexOf(@string[i++]) & unchecked(0xff));
                buffer[index++] = unchecked((byte)((int)(((uint)block) >> 16)));
                if (index < size)
                {
                    buffer[index++] = unchecked(
                        (byte)(
                            ((int)(((uint)block) >> 8)) & unchecked(0xff))
                        );
                }
                if (index < size)
                {
                    buffer[index++] = unchecked((byte)(block & unchecked(0xff)));
                }
            }
            return buffer;
        }
    }
}