Convert binary stream to byte array

        /// <summary>
        ///  Convert binary stream to byte array 
        /// </summary>
        /// <param name="_stream"></param>
        /// <returns></returns>
        private byte[] StreamtoBytes(Stream _stream)
        {
            byte[] buff;
            int rlen;
            MemoryStream _ms;
            if (_stream != null)
            {
                buff = new byte[1024];
                rlen = 0;
                _ms = new MemoryStream();
                while ((rlen = _stream.Read(buff, 0, 1024)) > 0)
                {
                    _ms.Write(buff, 0, rlen);
                }
                buff = _ms.ToArray();
                _ms.Close();
                _ms.Dispose();
                return buff;
            }
            return null;
        }