mirror of
https://github.com/ttttupup/wxhelper.git
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282 lines
8.9 KiB
C++
282 lines
8.9 KiB
C++
/*
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base64.cpp and base64.h
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base64 encoding and decoding with C++.
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More information at
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https://renenyffenegger.ch/notes/development/Base64/Encoding-and-decoding-base-64-with-cpp
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Version: 2.rc.09 (release candidate)
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Copyright (C) 2004-2017, 2020-2022 René Nyffenegger
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This source code is provided 'as-is', without any express or implied
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warranty. In no event will the author be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this source code must not be misrepresented; you must not
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claim that you wrote the original source code. If you use this source code
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original source code.
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3. This notice may not be removed or altered from any source distribution.
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René Nyffenegger rene.nyffenegger@adp-gmbh.ch
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*/
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#include "base64.h"
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#include <algorithm>
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#include <stdexcept>
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//
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// Depending on the url parameter in base64_chars, one of
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// two sets of base64 characters needs to be chosen.
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// They differ in their last two characters.
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//
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static const char* base64_chars[2] = {
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789"
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"+/",
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789"
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"-_" };
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static unsigned int pos_of_char(const unsigned char chr) {
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//
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// Return the position of chr within base64_encode()
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//
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if (chr >= 'A' && chr <= 'Z') return chr - 'A';
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else if (chr >= 'a' && chr <= 'z') return chr - 'a' + ('Z' - 'A') + 1;
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else if (chr >= '0' && chr <= '9') return chr - '0' + ('Z' - 'A') + ('z' - 'a') + 2;
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else if (chr == '+' || chr == '-') return 62; // Be liberal with input and accept both url ('-') and non-url ('+') base 64 characters (
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else if (chr == '/' || chr == '_') return 63; // Ditto for '/' and '_'
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else
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//
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// 2020-10-23: Throw std::exception rather than const char*
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//(Pablo Martin-Gomez, https://github.com/Bouska)
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//
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throw std::runtime_error("Input is not valid base64-encoded data.");
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}
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static std::string insert_linebreaks(std::string str, size_t distance) {
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//
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// Provided by https://github.com/JomaCorpFX, adapted by me.
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//
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if (!str.length()) {
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return "";
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}
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size_t pos = distance;
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while (pos < str.size()) {
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str.insert(pos, "\n");
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pos += distance + 1;
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}
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return str;
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}
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template <typename String, unsigned int line_length>
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static std::string encode_with_line_breaks(String s) {
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return insert_linebreaks(base64_encode(s, false), line_length);
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}
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template <typename String>
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static std::string encode_pem(String s) {
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return encode_with_line_breaks<String, 64>(s);
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}
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template <typename String>
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static std::string encode_mime(String s) {
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return encode_with_line_breaks<String, 76>(s);
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}
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template <typename String>
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static std::string encode(String s, bool url) {
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return base64_encode(reinterpret_cast<const unsigned char*>(s.data()), s.length(), url);
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}
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std::string base64_encode(unsigned char const* bytes_to_encode, size_t in_len, bool url) {
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size_t len_encoded = (in_len + 2) / 3 * 4;
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unsigned char trailing_char = url ? '.' : '=';
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//
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// Choose set of base64 characters. They differ
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// for the last two positions, depending on the url
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// parameter.
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// A bool (as is the parameter url) is guaranteed
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// to evaluate to either 0 or 1 in C++ therefore,
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// the correct character set is chosen by subscripting
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// base64_chars with url.
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//
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const char* base64_chars_ = base64_chars[url];
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std::string ret;
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ret.reserve(len_encoded);
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unsigned int pos = 0;
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while (pos < in_len) {
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ret.push_back(base64_chars_[(bytes_to_encode[pos + 0] & 0xfc) >> 2]);
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if (pos + 1 < in_len) {
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ret.push_back(base64_chars_[((bytes_to_encode[pos + 0] & 0x03) << 4) + ((bytes_to_encode[pos + 1] & 0xf0) >> 4)]);
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if (pos + 2 < in_len) {
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ret.push_back(base64_chars_[((bytes_to_encode[pos + 1] & 0x0f) << 2) + ((bytes_to_encode[pos + 2] & 0xc0) >> 6)]);
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ret.push_back(base64_chars_[bytes_to_encode[pos + 2] & 0x3f]);
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}
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else {
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ret.push_back(base64_chars_[(bytes_to_encode[pos + 1] & 0x0f) << 2]);
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ret.push_back(trailing_char);
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}
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}
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else {
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ret.push_back(base64_chars_[(bytes_to_encode[pos + 0] & 0x03) << 4]);
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ret.push_back(trailing_char);
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ret.push_back(trailing_char);
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}
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pos += 3;
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}
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return ret;
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}
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template <typename String>
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static std::string decode(String const& encoded_string, bool remove_linebreaks) {
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//
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// decode(…) is templated so that it can be used with String = const std::string&
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// or std::string_view (requires at least C++17)
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//
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if (encoded_string.empty()) return std::string();
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if (remove_linebreaks) {
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std::string copy(encoded_string);
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copy.erase(std::remove(copy.begin(), copy.end(), '\n'), copy.end());
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return base64_decode(copy, false);
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}
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size_t length_of_string = encoded_string.length();
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size_t pos = 0;
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//
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// The approximate length (bytes) of the decoded string might be one or
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// two bytes smaller, depending on the amount of trailing equal signs
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// in the encoded string. This approximation is needed to reserve
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// enough space in the string to be returned.
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//
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size_t approx_length_of_decoded_string = length_of_string / 4 * 3;
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std::string ret;
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ret.reserve(approx_length_of_decoded_string);
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while (pos < length_of_string) {
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//
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// Iterate over encoded input string in chunks. The size of all
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// chunks except the last one is 4 bytes.
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//
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// The last chunk might be padded with equal signs or dots
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// in order to make it 4 bytes in size as well, but this
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// is not required as per RFC 2045.
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//
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// All chunks except the last one produce three output bytes.
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//
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// The last chunk produces at least one and up to three bytes.
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//
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size_t pos_of_char_1 = pos_of_char(encoded_string.at(pos + 1));
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//
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// Emit the first output byte that is produced in each chunk:
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//
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ret.push_back(static_cast<std::string::value_type>(((pos_of_char(encoded_string.at(pos + 0))) << 2) + ((pos_of_char_1 & 0x30) >> 4)));
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if ((pos + 2 < length_of_string) && // Check for data that is not padded with equal signs (which is allowed by RFC 2045)
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encoded_string.at(pos + 2) != '=' &&
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encoded_string.at(pos + 2) != '.' // accept URL-safe base 64 strings, too, so check for '.' also.
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)
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{
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//
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// Emit a chunk's second byte (which might not be produced in the last chunk).
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//
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unsigned int pos_of_char_2 = pos_of_char(encoded_string.at(pos + 2));
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ret.push_back(static_cast<std::string::value_type>(((pos_of_char_1 & 0x0f) << 4) + ((pos_of_char_2 & 0x3c) >> 2)));
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if ((pos + 3 < length_of_string) &&
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encoded_string.at(pos + 3) != '=' &&
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encoded_string.at(pos + 3) != '.'
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)
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{
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//
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// Emit a chunk's third byte (which might not be produced in the last chunk).
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//
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ret.push_back(static_cast<std::string::value_type>(((pos_of_char_2 & 0x03) << 6) + pos_of_char(encoded_string.at(pos + 3))));
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}
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}
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pos += 4;
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}
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return ret;
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}
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std::string base64_decode(std::string const& s, bool remove_linebreaks) {
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return decode(s, remove_linebreaks);
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}
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std::string base64_encode(std::string const& s, bool url) {
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return encode(s, url);
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}
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std::string base64_encode_pem(std::string const& s) {
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return encode_pem(s);
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}
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std::string base64_encode_mime(std::string const& s) {
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return encode_mime(s);
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}
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#if __cplusplus >= 201703L
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//
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// Interface with std::string_view rather than const std::string&
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// Requires C++17
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// Provided by Yannic Bonenberger (https://github.com/Yannic)
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//
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std::string base64_encode(std::string_view s, bool url) {
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return encode(s, url);
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}
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std::string base64_encode_pem(std::string_view s) {
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return encode_pem(s);
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}
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std::string base64_encode_mime(std::string_view s) {
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return encode_mime(s);
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}
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std::string base64_decode(std::string_view s, bool remove_linebreaks) {
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return decode(s, remove_linebreaks);
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}
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#endif // __cplusplus >= 201703L
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