mirror of
https://git.rwth-aachen.de/acs/public/villas/node/
synced 2025-03-09 00:00:00 +01:00
121 lines
3.2 KiB
C++
121 lines
3.2 KiB
C++
/* Base64 encoding/decoding.
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*
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* Author: Steffen Vogel <post@steffenvogel.de>
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* SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <cstdint>
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#include <stdexcept>
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#include <string>
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#include <vector>
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#include <villas/utils.hpp>
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namespace villas {
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namespace utils {
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namespace base64 {
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static const char kEncodeLookup[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const char kPadCharacter = '=';
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std::string encode(const std::vector<byte> &input) {
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std::string encoded;
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encoded.reserve(((input.size() / 3) + (input.size() % 3 > 0)) * 4);
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std::uint32_t temp{};
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auto it = input.begin();
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for (std::size_t i = 0; i < input.size() / 3; ++i) {
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temp = (*it++) << 16;
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temp += (*it++) << 8;
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temp += (*it++);
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encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
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encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
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encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6]);
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encoded.append(1, kEncodeLookup[(temp & 0x0000003F)]);
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}
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switch (input.size() % 3) {
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case 1:
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temp = (*it++) << 16;
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encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
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encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
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encoded.append(2, kPadCharacter);
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break;
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case 2:
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temp = (*it++) << 16;
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temp += (*it++) << 8;
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encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
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encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
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encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6]);
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encoded.append(1, kPadCharacter);
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break;
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}
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return encoded;
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}
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std::vector<byte> decode(const std::string &input) {
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if (input.length() % 4)
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throw std::runtime_error("Invalid base64 length!");
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std::size_t padding{};
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if (input.length()) {
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if (input[input.length() - 1] == kPadCharacter)
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padding++;
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if (input[input.length() - 2] == kPadCharacter)
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padding++;
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}
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std::vector<byte> decoded;
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decoded.reserve(((input.length() / 4) * 3) - padding);
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std::uint32_t temp{};
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auto it = input.begin();
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while (it < input.end()) {
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for (std::size_t i = 0; i < 4; ++i) {
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temp <<= 6;
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if (*it >= 0x41 && *it <= 0x5A)
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temp |= *it - 0x41;
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else if (*it >= 0x61 && *it <= 0x7A)
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temp |= *it - 0x47;
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else if (*it >= 0x30 && *it <= 0x39)
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temp |= *it + 0x04;
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else if (*it == 0x2B)
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temp |= 0x3E;
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else if (*it == 0x2F)
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temp |= 0x3F;
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else if (*it == kPadCharacter) {
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switch (input.end() - it) {
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case 1:
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decoded.push_back((temp >> 16) & 0x000000FF);
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decoded.push_back((temp >> 8) & 0x000000FF);
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return decoded;
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case 2:
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decoded.push_back((temp >> 10) & 0x000000FF);
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return decoded;
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default:
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throw std::runtime_error("Invalid padding in base64!");
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}
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} else
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throw std::runtime_error("Invalid character in base64!");
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++it;
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}
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decoded.push_back((temp >> 16) & 0x000000FF);
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decoded.push_back((temp >> 8) & 0x000000FF);
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decoded.push_back((temp)&0x000000FF);
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}
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return decoded;
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}
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} // namespace base64
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} // namespace utils
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} // namespace villas
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