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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <fmt/format.h>
#include <sstream>
#include <string>
#include "mongo/base/string_data.h"
namespace mongo {
namespace base64_detail {
/**
* Abstract class used to split the translation formats below
* into something resembling namespaced implementations.
*/
template <typename Mode>
class Base64Impl {
private:
Base64Impl() = delete;
public:
/**
* Encode a payload to base64.
*/
static std::string encode(StringData in);
static std::string encode(const void* data, size_t len) {
return encode(StringData(reinterpret_cast<const char*>(data), len));
}
static void encode(std::stringstream& ss, StringData in);
static void encode(fmt::memory_buffer& buffer, StringData in);
/**
* Decode a base64 string to its original payload.
*/
static std::string decode(StringData in);
static void decode(std::stringstream& ss, StringData in);
static void decode(fmt::memory_buffer& buffer, StringData in);
/**
* Determines if a given string appears to be valid base64.
*/
static bool validate(StringData s);
/**
* Calculate how large a given input would expand to.
* Effectively: ceil(inLen * 4 / 3)
*/
static constexpr std::size_t encodedLength(std::size_t inLen) {
return (inLen + 2) / 3 * 4;
}
};
constexpr unsigned char kInvalid = ~0;
constexpr std::size_t search(StringData table, int c) {
for (std::size_t i = 0; i < table.size(); ++i) {
if (table[i] == c) {
return i;
}
}
return kInvalid;
}
template <std::size_t... Cs>
constexpr auto invertTable(StringData table, std::index_sequence<Cs...>) {
return std::array<unsigned char, sizeof...(Cs)>{
{static_cast<unsigned char>(search(table, Cs))...}};
}
struct Standard {
static constexpr auto kEncodeTable =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"_sd;
static constexpr auto kDecodeTable = invertTable(kEncodeTable, std::make_index_sequence<256>{});
static constexpr bool kTerminatorRequired = true;
};
// base64url encoding is a "url safe" variant of base64.
// '+' is replaced with '-'
// '/' is replaced with '_'
// '=' at the end of the string are optional
struct URL {
static constexpr auto kEncodeTable =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"_sd;
static constexpr auto kDecodeTable = invertTable(kEncodeTable, std::make_index_sequence<256>{});
static constexpr bool kTerminatorRequired = false;
};
} // namespace base64_detail
using base64 = typename base64_detail::Base64Impl<base64_detail::Standard>;
using base64url = typename base64_detail::Base64Impl<base64_detail::URL>;
} // namespace mongo
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