base64.h

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#pragma once
/*
 *   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; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   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
 */
 
/** Encode/decode binary data using printable characters (base64 format)
 *
 * @see RFC 4648 <http://www.ietf.org/rfc/rfc4648.txt>.
 *
 * @copyright 2021 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSIDH(base64_h, "$Id: 373ee0eacf8ba73c4f02fd5ebedc966ddc7ff9f5 $")
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include <freeradius-devel/missing.h>
#include <freeradius-devel/util/sbuff.h>
#include <freeradius-devel/util/dbuff.h>
 
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/types.h>
 
/*
 *      This uses that the expression (n+(k-1))/k means the smallest
 *      Integer >= n/k, i.e., the ceiling of n/k.
 */
#define FR_BASE64_ENC_LENGTH(_inlen) ((((_inlen) + 2) / 3) * 4)
#define FR_BASE64_DEC_LENGTH(_inlen) ((3 * ((_inlen) / 4)) + 2)
 
extern char const fr_base64_alphabet_encode[SBUFF_CHAR_CLASS];
extern uint8_t const fr_base64_alphabet_decode[SBUFF_CHAR_CLASS];
extern char const fr_base64_url_alphabet_encode[SBUFF_CHAR_CLASS];
extern uint8_t const fr_base64_url_alphabet_decode[SBUFF_CHAR_CLASS];
 
/** Check if char is in Base64 alphabet
 *
 * Note that '=' is padding and not considered to be part of the alphabet.
 *
 * @param[in] c         char to check.
 * @param[in] alphabet  to use.
 * @return
 *      - true if c is a character from the Base64 alphabet.
 *      - false if character is not in the Base64 alphabet.
 */
static inline bool fr_is_base64_nstd(char c, uint8_t const alphabet[static SBUFF_CHAR_CLASS])
{
        return alphabet[(uint8_t)c] < 64;
}
 
size_t          fr_base64_encode(char * restrict out, size_t outlen, uint8_t const * restrict in, size_t inlen);
#define         fr_is_base64(_c) fr_is_base64_nstd(_c, fr_base64_alphabet_decode)
 
 
ssize_t         fr_base64_encode_nstd(fr_sbuff_t *out, fr_dbuff_t *in,
                                      bool add_padding, char const alphabet[static SBUFF_CHAR_CLASS])
                                      CC_HINT(nonnull);
 
#define         fr_base64_encode(_out, _in, _add_padding) \
                fr_base64_encode_nstd(_out, _in, _add_padding, fr_base64_alphabet_encode)
 
ssize_t         fr_base64_decode_nstd(fr_sbuff_parse_error_t *err, fr_dbuff_t *out, fr_sbuff_t *in,
                                      bool expect_padding, bool no_trailing, uint8_t const alphabet[static SBUFF_CHAR_CLASS])
                                      CC_HINT(nonnull(2,3,6));
 
#define         fr_base64_decode(_out, _in, _expect_padding, _no_trailing) \
                fr_base64_decode_nstd(NULL, _out,  _in, _expect_padding, _no_trailing, fr_base64_alphabet_decode)
 
#ifdef __cplusplus
}
#endif