base64.h

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/******************************************************************************
The MIT License(MIT)
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
Copyright(c) 2024 John Wellbelove
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#ifndef ETL_BASE64_INCLUDED
#define ETL_BASE64_INCLUDED
 
#include "platform.h"
#include "static_assert.h"
#include "exception.h"
#include "error_handler.h"
#include "type_traits.h"
#include "enum_type.h"
#include "integral_limits.h"
 
#include <stdint.h>
 
/**************************************************************************************************************************************************************************
* See https://en.wikipedia.org/wiki/Base64
* 
* Encoding                                                  Encoding characters      Separate encoding of lines                           Decoding non-encoding characters
*                                                           62nd    63rd    Pad          Separators Length                          Checksum
* RFC 1421 : Base64 for Privacy - Enhanced Mail(deprecated)   +    /    = mandatory     CR + LF     64, or lower for the last line  No      No
* RFC 2045 : Base64 transfer encoding for MIME                +    /    = mandatory     CR + LF     At most 76  No                          Discarded
* RFC 2152 : Base64 for UTF - 7                               +    /    No           No                                                   No
* RFC 3501 : Base64 encoding for IMAP mailbox names           +    ,    No           No                                                   No
* RFC 4648 : base64(standard)[a]                              +    /    = optional   No                                                   No
* RFC 4648 : base64url(URL - and filename - safe standard)    -    _    = optional   No                                                   No
**************************************************************************************************************************************************************************/
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class base64_exception : public etl::exception
  {
  public:
 
    base64_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class base64_overflow : public base64_exception
  {
  public:
 
    base64_overflow(string_type file_name_, numeric_type line_number_)
      : base64_exception(ETL_ERROR_TEXT("base64:overflow", ETL_BASE64_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class base64_invalid_data : public base64_exception
  {
  public:
 
    base64_invalid_data(string_type file_name_, numeric_type line_number_)
      : base64_exception(ETL_ERROR_TEXT("base64:invalid data", ETL_BASE64_FILE_ID"B"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class base64_invalid_decode_input_length : public base64_exception
  {
  public:
 
    base64_invalid_decode_input_length(string_type file_name_, numeric_type line_number_)
      : base64_exception(ETL_ERROR_TEXT("base64:invalid decode input length", ETL_BASE64_FILE_ID"C"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class base64
  {
  public:
 
    struct Encoding
    {
      enum enum_type
      {
        //RFC_1421, // Not implemented
        //RFC_2045, // Not implemented
        RFC_2152,
        RFC_3501,
        RFC_4648,
        RFC_4648_PADDING,
        RFC_4648_URL,
        RFC_4648_URL_PADDING,
      };
 
      ETL_DECLARE_ENUM_TYPE(Encoding, int)
      //ETL_ENUM_TYPE(RFC_1421, "RFC_1421") // Not implemented
      //ETL_ENUM_TYPE(RFC_2045, "RFC_2045") // Not implemented
      ETL_ENUM_TYPE(RFC_2152,             "RFC_2152")
      ETL_ENUM_TYPE(RFC_3501,             "RFC_3501")
      ETL_ENUM_TYPE(RFC_4648,             "RFC_4648")
      ETL_ENUM_TYPE(RFC_4648_PADDING,     "RFC_4648_PADDING")
      ETL_ENUM_TYPE(RFC_4648_URL,         "RFC_4648_URL")
      ETL_ENUM_TYPE(RFC_4648_URL_PADDING, "RFC_4648_URL_PADDING")
      ETL_END_ENUM_TYPE
    };
 
    struct Padding
    {
      enum enum_type
      {
        No_Padding  = 0,
        Use_Padding = 1
      };
 
      ETL_DECLARE_ENUM_TYPE(Padding, bool)
      ETL_ENUM_TYPE(No_Padding,  "No_Padding")
      ETL_ENUM_TYPE(Use_Padding, "Use_Padding")
      ETL_END_ENUM_TYPE
    };
 
    struct Non_Coding_Characters
    {
      enum enum_type
      {
        Ignore = 0,
        Reject = 1
      };
 
      ETL_DECLARE_ENUM_TYPE(Non_Coding_Characters, bool)
      ETL_ENUM_TYPE(Ignore, "Ignore")
      ETL_ENUM_TYPE(Reject, "Reject")
      ETL_END_ENUM_TYPE
    };
 
    enum
    {
      Invalid_Data = etl::integral_limits<int>::max,
      Min_Encode_Buffer_Size = 4,
      Min_Decode_Buffer_Size = 3
    };
 
  protected:
 
    ETL_CONSTEXPR14
    base64(const char* encoder_table_,
           bool        use_padding_)
      : encoder_table(encoder_table_)
      , use_padding(use_padding_)
    {
    }
 
    //*************************************************************************
    // Character set for RFC-1421, RFC-2045, RFC-2152 and RFC-4648
    //*************************************************************************
    static
    ETL_CONSTEXPR14
    const char* character_set_1()
    {
      return "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    }
 
    //*************************************************************************
    // Character set for RFC-4648-URL
    //*************************************************************************
    static
    ETL_CONSTEXPR14
    const char* character_set_2()
    {
      return "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
    }
 
    //*************************************************************************
    // Character set for RFC-3501-URL
    //*************************************************************************
    static
    ETL_CONSTEXPR14
    const char* character_set_3()
    {
      return "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
    }
 
    const char* encoder_table;
    const bool  use_padding;
  };
}
#endif