# stdex: include/stdex/base64.hpp Source File

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base64.hpp
/*
SPDX-License-Identifier: MIT
Copyright © 2016-2023 Amebis
*/
#pragma once
#include "sal.hpp"
#include <assert.h>
#include <cstdint>
#include <string>
#include <vector>
namespace stdex
{
class base64_enc
{
public:
base64_enc() noexcept : num(0)
{
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
}
template<class _Elem, class _Traits, class _Ax>
void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out, _In_bytecount_(size) const void *data, _In_ size_t size, _In_opt_ bool is_last = true)
{
assert(data || !size);
// Preallocate output
out.reserve(out.size() + enc_size(size));
// Convert data character by character.
for (size_t i = 0;; i++) {
if (num >= 3) {
encode(out);
num = 0;
}
if (i >= size)
break;
buf[num++] = reinterpret_cast<const uint8_t*>(data)[i];
}
// If this is the last block, flush the buffer.
if (is_last && num) {
encode(out, num);
num = 0;
}
}
void clear() noexcept
{
num = 0;
}
size_t enc_size(_In_ size_t size) const noexcept
{
return ((num + size + 2)/3)*4;
}
protected:
template<class _Elem, class _Traits, class _Ax>
void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out)
{
out += base64_enc_lookup[ buf[0] >> 2 ];
out += base64_enc_lookup[((buf[0] << 4) | (buf[1] >> 4)) & 0x3f];
out += base64_enc_lookup[((buf[1] << 2) | (buf[2] >> 6)) & 0x3f];
out += base64_enc_lookup[ buf[2] & 0x3f];
}
template<class _Elem, class _Traits, class _Ax>
void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out, _In_ size_t size)
{
if (size > 0) {
out += base64_enc_lookup[buf[0] >> 2];
if (size > 1) {
out += base64_enc_lookup[((buf[0] << 4) | (buf[1] >> 4)) & 0x3f];
if (size > 2) {
out += base64_enc_lookup[((buf[1] << 2) | (buf[2] >> 6)) & 0x3f];
out += base64_enc_lookup[buf[2] & 0x3f];
} else {
out += base64_enc_lookup[(buf[1] << 2) & 0x3f];
out += '=';
}
} else {
out += base64_enc_lookup[(buf[0] << 4) & 0x3f];
out += '=';
out += '=';
}
} else {
out += '=';
out += '=';
out += '=';
out += '=';
}
}
protected:
uint8_t buf[3];
size_t num;
};
static const char base64_enc_lookup[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', '+', '/'
};
class base64_dec
{
public:
base64_dec() noexcept : num(0)
{
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
buf[3] = 0;
}
template<class _Ty, class _Ax, class _Tchr>
void decode(_Inout_ std::vector<_Ty, _Ax> &out, _Out_ bool &is_last, _In_z_count_(size) const _Tchr *data, _In_ size_t size)
{
is_last = false;
// Trim data size to first terminator.
for (size_t k = 0; k < size; k++)
if (!data[k]) { size = k; break; }
// Preallocate output
out.reserve(out.size() + dec_size(size));
for (size_t i = 0;; i++) {
if (num >= 4) {
// Buffer full; decode it.
size_t nibbles = decode(out);
num = 0;
if (nibbles < 3) {
is_last = true;
break;
}
}
if (i >= size)
break;
int x = data[i];
if ((buf[num] = x < _countof(base64_dec_lookup) ? base64_dec_lookup[x] : 255) != 255)
num++;
}
}
void clear() noexcept
{
num = 0;
}
size_t dec_size(_In_ size_t size) const noexcept
{
return ((num + size + 3)/4)*3;
}
protected:
template<class _Ty, class _Ax>
size_t decode(_Inout_ std::vector<_Ty, _Ax> &out)
{
out.push_back((_Ty)(((buf[0] << 2) | (buf[1] >> 4)) & 0xff));
if (buf[2] < 64) {
out.push_back((_Ty)(((buf[1] << 4) | (buf[2] >> 2)) & 0xff));
if (buf[3] < 64) {
out.push_back((_Ty)(((buf[2] << 6) | buf[3]) & 0xff));
return 3;
} else
return 2;
} else
return 1;
}
protected:
uint8_t buf[4];
size_t num;
};
static const uint8_t base64_dec_lookup[256] = {
/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
/* 0 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* 1 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* 2 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
/* 3 */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 64, 255, 255,
/* 4 */ 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
/* 5 */ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
/* 6 */ 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
/* 7 */ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 255, 255, 255, 255, 255,
/* 8 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* 9 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* A */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* B */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* C */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* D */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* E */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
/* F */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255
};
}
stdex::base64_dec
Base64 decoding session.
Definition base64.hpp:158
stdex::base64_dec::num
size_t num
Number of bytes used in buf
Definition base64.hpp:257
stdex::base64_dec::base64_dec
base64_dec() noexcept
Constructs blank decoding session.
Definition base64.hpp:163
stdex::base64_dec::decode
void decode(std::vector< _Ty, _Ax > &out, bool &is_last, const _Tchr *data, size_t size)
Decodes one block of information, and appends it to the output.
Definition base64.hpp:181
stdex::base64_dec::dec_size
size_t dec_size(size_t size) const noexcept
Returns maximum decoded size.
Definition base64.hpp:229
stdex::base64_dec::buf
uint8_t buf[4]
Internal buffer.
Definition base64.hpp:256
stdex::base64_dec::decode
size_t decode(std::vector< _Ty, _Ax > &out)
Decodes one complete internal buffer of data.
Definition base64.hpp:240
stdex::base64_dec::clear
void clear() noexcept
Resets decoding session.
Definition base64.hpp:216
stdex::base64_enc
Base64 encoding session.
Definition base64.hpp:21
stdex::base64_enc::encode
void encode(std::basic_string< _Elem, _Traits, _Ax > &out, const void *data, size_t size, bool is_last=true)
Encodes one block of information, and appends it to the output.
Definition base64.hpp:43
stdex::base64_enc::encode
void encode(std::basic_string< _Elem, _Traits, _Ax > &out)
Encodes one complete internal buffer of data.
Definition base64.hpp:98
stdex::base64_enc::num
size_t num
Number of bytes used in buf
Definition base64.hpp:140
stdex::base64_enc::encode
void encode(std::basic_string< _Elem, _Traits, _Ax > &out, size_t size)
Encodes partial internal buffer of data.
Definition base64.hpp:111
stdex::base64_enc::base64_enc
base64_enc() noexcept
Constructs blank encoding session.
Definition base64.hpp:26
stdex::base64_enc::buf
uint8_t buf[3]
Internal buffer.
Definition base64.hpp:139
stdex::base64_enc::clear
void clear() noexcept
Resets encoding session.
Definition base64.hpp:74
stdex::base64_enc::enc_size
size_t enc_size(size_t size) const noexcept
Returns maximum encoded size.
Definition base64.hpp:87