235 lines
6.3 KiB
C++
235 lines
6.3 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include "td/utils/base64.h"
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#include "td/utils/common.h"
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#include "td/utils/Slice.h"
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#include "td/utils/Status.h"
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#include <algorithm>
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#include <iterator>
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namespace td {
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template <bool is_url>
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static const char *get_characters() {
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return is_url ? "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
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: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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}
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template <bool is_url>
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static const unsigned char *get_character_table() {
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static unsigned char char_to_value[256];
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static bool is_inited = [] {
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auto characters = get_characters<is_url>();
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std::fill(std::begin(char_to_value), std::end(char_to_value), static_cast<unsigned char>(64));
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for (unsigned char i = 0; i < 64; i++) {
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char_to_value[static_cast<size_t>(characters[i])] = i;
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}
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return true;
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}();
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CHECK(is_inited);
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return char_to_value;
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}
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template <bool is_url>
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string base64_encode_impl(Slice input) {
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auto characters = get_characters<is_url>();
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string base64;
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base64.reserve((input.size() + 2) / 3 * 4);
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for (size_t i = 0; i < input.size();) {
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size_t left = min(input.size() - i, static_cast<size_t>(3));
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int c = input.ubegin()[i++] << 16;
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base64 += characters[c >> 18];
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if (left != 1) {
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c |= input.ubegin()[i++] << 8;
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}
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base64 += characters[(c >> 12) & 63];
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if (left == 3) {
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c |= input.ubegin()[i++];
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}
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if (left != 1) {
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base64 += characters[(c >> 6) & 63];
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} else if (!is_url) {
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base64 += '=';
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}
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if (left == 3) {
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base64 += characters[c & 63];
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} else if (!is_url) {
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base64 += '=';
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}
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}
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return base64;
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}
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template <bool is_url>
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Result<Slice> base64_drop_padding(Slice base64) {
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size_t padding_length = 0;
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while (!base64.empty() && base64.back() == '=') {
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base64.remove_suffix(1);
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padding_length++;
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}
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if (padding_length >= 3) {
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return Status::Error("Wrong string padding");
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}
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if ((!is_url || padding_length > 0) && ((base64.size() + padding_length) & 3) != 0) {
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return Status::Error("Wrong padding length");
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}
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if (is_url && (base64.size() & 3) == 1) {
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return Status::Error("Wrong string length");
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}
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return base64;
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}
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template <bool is_url, class F>
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Status base64_do_decode(Slice base64, F &&append) {
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auto table = get_character_table<is_url>();
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for (size_t i = 0; i < base64.size();) {
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size_t left = min(base64.size() - i, static_cast<size_t>(4));
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int c = 0;
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for (size_t t = 0; t < left; t++) {
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auto value = table[base64.ubegin()[i++]];
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if (value == 64) {
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return Status::Error("Wrong character in the string");
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}
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c |= value << ((3 - t) * 6);
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}
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append(static_cast<char>(static_cast<unsigned char>(c >> 16))); // implementation-defined
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if (left == 2) {
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if ((c & ((1 << 16) - 1)) != 0) {
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return Status::Error("Wrong padding in the string");
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}
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} else {
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append(static_cast<char>(static_cast<unsigned char>(c >> 8))); // implementation-defined
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if (left == 3) {
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if ((c & ((1 << 8) - 1)) != 0) {
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return Status::Error("Wrong padding in the string");
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}
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} else {
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append(static_cast<char>(static_cast<unsigned char>(c))); // implementation-defined
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}
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}
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}
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return Status::OK();
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}
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Result<string> base64_decode(Slice base64) {
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TRY_RESULT_ASSIGN(base64, base64_drop_padding<false>(base64));
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string output;
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output.reserve((base64.size() >> 2) * 3 + (((base64.size() & 3) + 1) >> 1));
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TRY_STATUS(base64_do_decode<false>(base64, [&output](char c) { output += c; }));
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return output;
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}
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Result<SecureString> base64_decode_secure(Slice base64) {
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TRY_RESULT_ASSIGN(base64, base64_drop_padding<false>(base64));
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SecureString output((base64.size() >> 2) * 3 + (((base64.size() & 3) + 1) >> 1));
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char *ptr = output.as_mutable_slice().begin();
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TRY_STATUS(base64_do_decode<false>(base64, [&ptr](char c) { *ptr++ = c; }));
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return std::move(output);
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}
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string base64_encode(Slice input) {
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return base64_encode_impl<false>(input);
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}
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string base64url_encode(Slice input) {
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return base64_encode_impl<true>(input);
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}
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Result<string> base64url_decode(Slice base64) {
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TRY_RESULT_ASSIGN(base64, base64_drop_padding<true>(base64));
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string output;
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output.reserve((base64.size() >> 2) * 3 + (((base64.size() & 3) + 1) >> 1));
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TRY_STATUS(base64_do_decode<true>(base64, [&output](char c) { output += c; }));
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return output;
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}
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template <bool is_url>
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static bool is_base64_impl(Slice input) {
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size_t padding_length = 0;
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while (!input.empty() && input.back() == '=') {
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input.remove_suffix(1);
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padding_length++;
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}
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if (padding_length >= 3) {
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return false;
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}
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if ((!is_url || padding_length > 0) && ((input.size() + padding_length) & 3) != 0) {
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return false;
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}
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if (is_url && (input.size() & 3) == 1) {
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return false;
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}
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auto table = get_character_table<is_url>();
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for (auto c : input) {
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if (table[static_cast<unsigned char>(c)] == 64) {
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return false;
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}
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}
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if ((input.size() & 3) == 2) {
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auto value = table[static_cast<int>(input.back())];
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if ((value & 15) != 0) {
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return false;
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}
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}
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if ((input.size() & 3) == 3) {
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auto value = table[static_cast<int>(input.back())];
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if ((value & 3) != 0) {
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return false;
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}
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}
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return true;
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}
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bool is_base64(Slice input) {
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return is_base64_impl<false>(input);
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}
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bool is_base64url(Slice input) {
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return is_base64_impl<true>(input);
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}
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template <bool is_url>
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static bool is_base64_characters_impl(Slice input) {
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auto table = get_character_table<is_url>();
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for (auto c : input) {
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if (table[static_cast<unsigned char>(c)] == 64) {
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return false;
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}
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}
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return true;
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}
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bool is_base64_characters(Slice input) {
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return is_base64_characters_impl<false>(input);
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}
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bool is_base64url_characters(Slice input) {
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return is_base64_characters_impl<true>(input);
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}
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string base64_filter(Slice input) {
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auto table = get_character_table<false>();
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string res;
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res.reserve(input.size());
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for (auto c : input) {
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if (table[static_cast<unsigned char>(c)] != 64 || c == '=') {
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res += c;
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}
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}
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return res;
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}
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} // namespace td
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