rtems/cpukit/base64/base64-encode.c

/* SPDX-License-Identifier: ISC */

/**
 * @file
 *
 * @ingroup RTEMSImplBase64
 *
 * @brief This source file contains the implementation of
 *   _Base64_Encode() and _Base64url_Encode().
 */

/*
 * Copyright (C) 2020, 2024 embedded brains GmbH & Co. KG
 * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1998-2001, 2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include <rtems/base64.h>

static void _Base64_Put( int c, void *arg, IO_Put_char put_char )
{
  ( *put_char )( c, arg );
}

static int _Base64_Do_encode(
  IO_Put_char    put_char,
  void          *arg,
  const void    *src,
  size_t         srclen,
  const char    *wordbreak,
  int            wordlen,
  const uint8_t *encoding
)
{
  unsigned int         loops = 0;
  const unsigned char *in = src;
  int                  out = 0;

  if ( wordlen < 4 ) {
    wordlen = 4;
  }

  while ( srclen > 2 ) {
    _Base64_Put( encoding[ ( in[ 0 ] >> 2 ) & 0x3f ], arg, put_char );
    _Base64_Put(
      encoding[ ( ( in[ 0 ] << 4 ) & 0x30 ) | ( ( in[ 1 ] >> 4 ) & 0x0f ) ],
      arg,
      put_char
    );
    _Base64_Put(
      encoding[ ( ( in[ 1 ] << 2 ) & 0x3c ) | ( ( in[ 2 ] >> 6 ) & 0x03 ) ],
      arg,
      put_char
    );
    _Base64_Put( encoding[ in[ 2 ] & 0x3f ], arg, put_char );
    in += 3;
    srclen -= 3;
    out += 4;

    loops++;
    if ( srclen != 0 && (int) ( ( loops + 1 ) * 4 ) >= wordlen ) {
      const char *w = wordbreak;
      loops = 0;
      while ( *w != '\0' ) {
        _Base64_Put( *w, arg, put_char );
        ++w;
        ++out;
      }
    }
  }
  if ( srclen == 2 ) {
    _Base64_Put( encoding[ ( in[ 0 ] >> 2 ) & 0x3f ], arg, put_char );
    _Base64_Put(
      encoding[ ( ( in[ 0 ] << 4 ) & 0x30 ) | ( ( in[ 1 ] >> 4 ) & 0x0f ) ],
      arg,
      put_char
    );
    _Base64_Put( encoding[ ( ( in[ 1 ] << 2 ) & 0x3c ) ], arg, put_char );
    _Base64_Put( '=', arg, put_char );
    out += 4;
  } else if ( srclen == 1 ) {
    _Base64_Put( encoding[ ( in[ 0 ] >> 2 ) & 0x3f ], arg, put_char );
    _Base64_Put( encoding[ ( ( in[ 0 ] << 4 ) & 0x30 ) ], arg, put_char );
    _Base64_Put( '=', arg, put_char );
    _Base64_Put( '=', arg, put_char );
    out += 4;
  }
  return out;
}

// clang-format off
const uint8_t _Base64_Encoding[64] = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
    'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
    'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
    't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', '+', '/'
};
// clang-format on

int _Base64_Encode(
  IO_Put_char put_char,
  void       *arg,
  const void *src,
  size_t      srclen,
  const char *wordbreak,
  int         wordlen
)
{
  return _Base64_Do_encode(
    put_char,
    arg,
    src,
    srclen,
    wordbreak,
    wordlen,
    _Base64_Encoding
  );
}

// clang-format off
const uint8_t _Base64url_Encoding[64] = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
    'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
    'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
    't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', '-', '_'
};
// clang-format on

int _Base64url_Encode(
  IO_Put_char put_char,
  void       *arg,
  const void *src,
  size_t      srclen,
  const char *wordbreak,
  int         wordlen
)
{
  return _Base64_Do_encode(
    put_char,
    arg,
    src,
    srclen,
    wordbreak,
    wordlen,
    _Base64url_Encoding
  );
}