141 lines
4.0 KiB
C++
141 lines
4.0 KiB
C++
/* SPDX-License-Identifier: BSL-1.0 OR BSD-3-Clause */
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#ifndef MPT_BINARY_BASE64URL_HPP
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#define MPT_BINARY_BASE64URL_HPP
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#include "mpt/base/integer.hpp"
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#include "mpt/base/memory.hpp"
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#include "mpt/base/namespace.hpp"
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#include "mpt/string/types.hpp"
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#include <array>
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#include <stdexcept>
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#include <vector>
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#include <cstddef>
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namespace mpt {
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inline namespace MPT_INLINE_NS {
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class base64url_parse_error : public std::runtime_error {
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public:
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base64url_parse_error()
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: std::runtime_error("invalid Base64URL encoding") {
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}
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};
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inline constexpr std::array<mpt::uchar, 64> base64url = {
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{MPT_UCHAR('A'), MPT_UCHAR('B'), MPT_UCHAR('C'), MPT_UCHAR('D'), MPT_UCHAR('E'), MPT_UCHAR('F'), MPT_UCHAR('G'), MPT_UCHAR('H'), MPT_UCHAR('I'), MPT_UCHAR('J'), MPT_UCHAR('K'), MPT_UCHAR('L'), MPT_UCHAR('M'), MPT_UCHAR('N'), MPT_UCHAR('O'), MPT_UCHAR('P'),
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MPT_UCHAR('Q'), MPT_UCHAR('R'), MPT_UCHAR('S'), MPT_UCHAR('T'), MPT_UCHAR('U'), MPT_UCHAR('V'), MPT_UCHAR('W'), MPT_UCHAR('X'), MPT_UCHAR('Y'), MPT_UCHAR('Z'), MPT_UCHAR('a'), MPT_UCHAR('b'), MPT_UCHAR('c'), MPT_UCHAR('d'), MPT_UCHAR('e'), MPT_UCHAR('f'),
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MPT_UCHAR('g'), MPT_UCHAR('h'), MPT_UCHAR('i'), MPT_UCHAR('j'), MPT_UCHAR('k'), MPT_UCHAR('l'), MPT_UCHAR('m'), MPT_UCHAR('n'), MPT_UCHAR('o'), MPT_UCHAR('p'), MPT_UCHAR('q'), MPT_UCHAR('r'), MPT_UCHAR('s'), MPT_UCHAR('t'), MPT_UCHAR('u'), MPT_UCHAR('v'),
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MPT_UCHAR('w'), MPT_UCHAR('x'), MPT_UCHAR('y'), MPT_UCHAR('z'), MPT_UCHAR('0'), MPT_UCHAR('1'), MPT_UCHAR('2'), MPT_UCHAR('3'), MPT_UCHAR('4'), MPT_UCHAR('5'), MPT_UCHAR('6'), MPT_UCHAR('7'), MPT_UCHAR('8'), MPT_UCHAR('9'), MPT_UCHAR('-'), MPT_UCHAR('_')}
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};
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template <typename Tbyte>
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inline mpt::ustring encode_base64url(mpt::span<Tbyte> src_) {
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mpt::const_byte_span src = mpt::byte_cast<mpt::const_byte_span>(src_);
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mpt::ustring result;
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result.reserve(4 * ((src.size() + 2) / 3));
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uint32 bits = 0;
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std::size_t bytes = 0;
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for (std::byte byte : src) {
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bits <<= 8;
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bits |= mpt::byte_cast<uint8>(byte);
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bytes++;
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if (bytes == 3) {
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result.push_back(base64url[(bits >> 18) & 0x3f]);
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result.push_back(base64url[(bits >> 12) & 0x3f]);
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result.push_back(base64url[(bits >> 6) & 0x3f]);
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result.push_back(base64url[(bits >> 0) & 0x3f]);
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bits = 0;
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bytes = 0;
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}
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}
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std::size_t padding = 0;
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while (bytes != 0) {
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bits <<= 8;
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padding++;
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bytes++;
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if (bytes == 3) {
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result.push_back(base64url[(bits >> 18) & 0x3f]);
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result.push_back(base64url[(bits >> 12) & 0x3f]);
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if (padding <= 1) {
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result.push_back(base64url[(bits >> 6) & 0x3f]);
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}
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if (padding <= 0) {
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result.push_back(base64url[(bits >> 0) & 0x3f]);
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}
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bits = 0;
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bytes = 0;
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}
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}
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return result;
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}
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inline uint8 decode_base64url_bits(mpt::uchar c) {
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for (uint8 i = 0; i < 64; ++i)
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{
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if (base64url[i] == c)
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{
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return i;
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}
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}
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throw base64url_parse_error();
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}
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inline std::vector<std::byte> decode_base64url(const mpt::ustring & src) {
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std::vector<std::byte> result;
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result.reserve(3 * ((src.length() + 2) / 4));
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uint32 bits = 0;
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std::size_t chars = 0;
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for (mpt::uchar c : src) {
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bits <<= 6;
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bits |= decode_base64url_bits(c);
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chars++;
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if (chars == 4) {
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 16) & 0xff)));
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 8) & 0xff)));
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 0) & 0xff)));
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bits = 0;
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chars = 0;
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}
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}
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uint32 padding = 0;
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if (chars != 0 && chars < 2) {
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throw base64url_parse_error();
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}
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while (chars != 0) {
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bits <<= 6;
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padding++;
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chars++;
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if (chars == 4) {
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 16) & 0xff)));
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if (padding < 2) {
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 8) & 0xff)));
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}
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if (padding < 1) {
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result.push_back(mpt::byte_cast<std::byte>(static_cast<uint8>((bits >> 0) & 0xff)));
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}
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bits = 0;
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chars = 0;
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padding = 0;
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}
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}
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return result;
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}
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} // namespace MPT_INLINE_NS
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} // namespace mpt
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#endif // MPT_BINARY_BASE64URL_HPP
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