File syn_base64.c¶

FileList > src > syntropic > util > syn_base64.c

RFC 4648 Base64 and Base64URL codec implementation.

#include "syn_base64.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

Public Static Attributes¶

Type	Name
const char	B64_STD_TABLE = `/* multi line expression /` Standard RFC 4648 Base64 character encoding table.*
const char	B64_URL_TABLE = `/* multi line expression /` URL and filename-safe RFC 4648 Base64URL character encoding table.*

Public Functions¶

Type	Name
bool	syn_base64_decode (const char * src, size_t src_len, uint8_t * dst, size_t dst_size, size_t * out_len) Decode an RFC 4648 standard Base64 string into binary data.
bool	syn_base64_encode (const uint8_t * src, size_t src_len, char * dst, size_t dst_size, size_t * out_len) Encode binary data to standard RFC 4648 Base64 string.
bool	syn_base64url_decode (const char * src, size_t src_len, uint8_t * dst, size_t dst_size, size_t * out_len) Decode an RFC 4648 Base64URL string into binary data.
bool	syn_base64url_encode (const uint8_t * src, size_t src_len, char * dst, size_t dst_size, bool with_padding, size_t * out_len) Encode binary data to RFC 4648 Base64URL string.

Public Static Functions¶

Type	Name
bool	base64_decode_internal (const char * src, size_t src_len, uint8_t * dst, size_t dst_size, size_t * out_len, bool url_mode) Internal shared decoder for standard and URL-safe Base64.
uint8_t	decode_char (char c, bool url_mode) Decode single ASCII character into 6-bit value or control marker.

Macros¶

Type	Name
define	B64_VAL_INVALID `0xFFU` Marker value for non-base64 character.
define	B64_VAL_PAD `0xFEU` Marker value for base64 padding '=' character.
define	B64_VAL_WS `0xFDU` Marker value for whitespace character.

Public Static Attributes Documentation¶

variable B64_STD_TABLE¶

Standard RFC 4648 Base64 character encoding table.

const char B64_STD_TABLE[];

variable B64_URL_TABLE¶

URL and filename-safe RFC 4648 Base64URL character encoding table.

const char B64_URL_TABLE[];

Public Functions Documentation¶

function syn_base64_decode¶

Decode an RFC 4648 standard Base64 string into binary data.

bool syn_base64_decode (
    const char * src,
    size_t src_len,
    uint8_t * dst,
    size_t dst_size,
    size_t * out_len
)

Automatically skips whitespace characters (spaces, tabs, CR, LF). Rejects invalid non-base64 characters and malformed padding.

Parameters:

src Input Base64 string (null-terminated or bounded by src_len).
src_len Length of input string (or 0 to determine via strlen).
dst [out] Output binary buffer.
dst_size Capacity of output buffer in bytes.
out_len [out] Optional pointer to receive actual binary bytes written.

Returns:

true on success, false if input contains invalid characters or destination is too small.

function syn_base64_encode¶

Encode binary data to standard RFC 4648 Base64 string.

bool syn_base64_encode (
    const uint8_t * src,
    size_t src_len,
    char * dst,
    size_t dst_size,
    size_t * out_len
)

Uses alphabet [A-Za-z0-9+/] and adds = padding when needed. Always null-terminates the output if dst_size > 0.

Parameters:

src Input binary data.
src_len Length of input binary data in bytes.
dst [out] Output string buffer.
dst_size Capacity of output buffer in bytes (must be >= syn_base64_calc_encoded_size(src_len)).
out_len [out] Optional pointer to receive character length written (excluding null).

Returns:

true on success, false if parameters are invalid or buffer is too small.

function syn_base64url_decode¶

Decode an RFC 4648 Base64URL string into binary data.

bool syn_base64url_decode (
    const char * src,
    size_t src_len,
    uint8_t * dst,
    size_t dst_size,
    size_t * out_len
)

Supports both padded (=) and unpadded URL-safe strings.

Parameters:

src Input Base64URL string.
src_len Length of input string (or 0 to determine via strlen).
dst [out] Output binary buffer.
dst_size Capacity of output buffer in bytes.
out_len [out] Optional pointer to receive actual binary bytes written.

Returns:

true on success, false on invalid input or insufficient buffer capacity.

function syn_base64url_encode¶

Encode binary data to RFC 4648 Base64URL string.

bool syn_base64url_encode (
    const uint8_t * src,
    size_t src_len,
    char * dst,
    size_t dst_size,
    bool with_padding,
    size_t * out_len
)

Uses URL-safe alphabet [A-Za-z0-9-_].

Parameters:

src Input binary data.
src_len Length of input binary data in bytes.
dst [out] Output string buffer.
dst_size Capacity of output buffer in bytes.
with_padding If true, appends = padding; if false, omits padding (standard JWT format).
out_len [out] Optional pointer to receive character length written (excluding null).

Returns:

true on success, false if buffer is too small or parameters invalid.

Public Static Functions Documentation¶

function base64_decode_internal¶

Internal shared decoder for standard and URL-safe Base64.

static bool base64_decode_internal (
    const char * src,
    size_t src_len,
    uint8_t * dst,
    size_t dst_size,
    size_t * out_len,
    bool url_mode
)

Parameters:

src Input Base64 string buffer.
src_len Length of input string (or 0 for strlen).
dst [out] Output destination binary buffer.
dst_size Capacity of destination buffer in bytes.
out_len [out] Pointer to receive decoded byte count.
url_mode True for URL-safe alphabet, false for standard RFC 4648.

Returns:

True on success, false on decode error or buffer overflow.

function decode_char¶

Decode single ASCII character into 6-bit value or control marker.

static uint8_t decode_char (
    char c,
    bool url_mode
)

Parameters:

c ASCII character to decode.
url_mode True if decoding in URL-safe mode (- and _).

Returns:

6-bit value (0-63) or marker constant (B64_VAL_PAD, B64_VAL_WS, B64_VAL_INVALID).

Macro Definition Documentation¶

define B64_VAL_INVALID¶

Marker value for non-base64 character.

#define B64_VAL_INVALID `0xFFU`

define B64_VAL_PAD¶

Marker value for base64 padding '=' character.

#define B64_VAL_PAD `0xFEU`

define B64_VAL_WS¶

Marker value for whitespace character.

#define B64_VAL_WS `0xFDU`

The documentation for this class was generated from the following file src/syntropic/util/syn_base64.c