tdlight/tdutils/td/utils/base64.cpp

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/base64.h"
#include "td/utils/common.h"
#include "td/utils/Slice.h"
#include "td/utils/Status.h"
#include <algorithm>
#include <iterator>
namespace td {
template <bool is_url>
static const char *get_characters() {
return is_url ? "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
}
template <bool is_url>
static const unsigned char *get_character_table() {
static unsigned char char_to_value[256];
static bool is_inited = [] {
auto characters = get_characters<is_url>();
std::fill(std::begin(char_to_value), std::end(char_to_value), static_cast<unsigned char>(64));
for (unsigned char i = 0; i < 64; i++) {
char_to_value[static_cast<size_t>(characters[i])] = i;
}
return true;
}();
CHECK(is_inited);
return char_to_value;
}
template <bool is_url>
string base64_encode_impl(Slice input) {
auto characters = get_characters<is_url>();
string base64;
base64.reserve((input.size() + 2) / 3 * 4);
for (size_t i = 0; i < input.size();) {
size_t left = min(input.size() - i, static_cast<size_t>(3));
int c = input.ubegin()[i++] << 16;
base64 += characters[c >> 18];
if (left != 1) {
c |= input.ubegin()[i++] << 8;
}
base64 += characters[(c >> 12) & 63];
if (left == 3) {
c |= input.ubegin()[i++];
}
if (left != 1) {
base64 += characters[(c >> 6) & 63];
} else if (!is_url) {
base64 += '=';
}
if (left == 3) {
base64 += characters[c & 63];
} else if (!is_url) {
base64 += '=';
}
}
return base64;
}
string base64_encode(Slice input) {
return base64_encode_impl<false>(input);
}
string base64url_encode(Slice input) {
return base64_encode_impl<true>(input);
}
template <bool is_url>
Result<Slice> base64_drop_padding(Slice base64) {
size_t padding_length = 0;
while (!base64.empty() && base64.back() == '=') {
base64.remove_suffix(1);
padding_length++;
}
if (padding_length >= 3) {
return Status::Error("Wrong string padding");
}
if ((!is_url || padding_length > 0) && ((base64.size() + padding_length) & 3) != 0) {
return Status::Error("Wrong padding length");
}
if (is_url && (base64.size() & 3) == 1) {
return Status::Error("Wrong string length");
}
return base64;
}
static Status do_base64_decode_impl(Slice base64, const unsigned char *table, char *ptr) {
for (size_t i = 0; i < base64.size();) {
size_t left = min(base64.size() - i, static_cast<size_t>(4));
int c = 0;
for (size_t t = 0; t < left; t++) {
auto value = table[base64.ubegin()[i++]];
if (value == 64) {
return Status::Error("Wrong character in the string");
}
c |= value << ((3 - t) * 6);
}
*ptr++ = static_cast<char>(static_cast<unsigned char>(c >> 16)); // implementation-defined
if (left == 2) {
if ((c & ((1 << 16) - 1)) != 0) {
return Status::Error("Wrong padding in the string");
}
} else {
*ptr++ = static_cast<char>(static_cast<unsigned char>(c >> 8)); // implementation-defined
if (left == 3) {
if ((c & ((1 << 8) - 1)) != 0) {
return Status::Error("Wrong padding in the string");
}
} else {
*ptr++ = static_cast<char>(static_cast<unsigned char>(c)); // implementation-defined
}
}
}
return Status::OK();
}
template <class T>
static T create_empty(size_t size);
template <>
string create_empty<string>(size_t size) {
return string(size, '\0');
}
template <>
SecureString create_empty<SecureString>(size_t size) {
return SecureString{size};
}
template <bool is_url, class T>
static Result<T> base64_decode_impl(Slice base64) {
TRY_RESULT_ASSIGN(base64, base64_drop_padding<is_url>(base64));
T result = create_empty<T>(base64.size() / 4 * 3 + ((base64.size() & 3) + 1) / 2);
TRY_STATUS(do_base64_decode_impl(base64, get_character_table<is_url>(), as_mutable_slice(result).begin()));
return std::move(result);
}
Result<string> base64_decode(Slice base64) {
return base64_decode_impl<false, string>(base64);
}
Result<SecureString> base64_decode_secure(Slice base64) {
return base64_decode_impl<false, SecureString>(base64);
}
Result<string> base64url_decode(Slice base64) {
return base64_decode_impl<true, string>(base64);
}
template <bool is_url>
static bool is_base64_impl(Slice input) {
size_t padding_length = 0;
while (!input.empty() && input.back() == '=') {
input.remove_suffix(1);
padding_length++;
}
if (padding_length >= 3) {
return false;
}
if ((!is_url || padding_length > 0) && ((input.size() + padding_length) & 3) != 0) {
return false;
}
if (is_url && (input.size() & 3) == 1) {
return false;
}
auto table = get_character_table<is_url>();
for (auto c : input) {
if (table[static_cast<unsigned char>(c)] == 64) {
return false;
}
}
if ((input.size() & 3) == 2) {
auto value = table[static_cast<int>(input.back())];
if ((value & 15) != 0) {
return false;
}
}
if ((input.size() & 3) == 3) {
auto value = table[static_cast<int>(input.back())];
if ((value & 3) != 0) {
return false;
}
}
return true;
}
bool is_base64(Slice input) {
return is_base64_impl<false>(input);
}
bool is_base64url(Slice input) {
return is_base64_impl<true>(input);
}
template <bool is_url>
static bool is_base64_characters_impl(Slice input) {
auto table = get_character_table<is_url>();
for (auto c : input) {
if (table[static_cast<unsigned char>(c)] == 64) {
return false;
}
}
return true;
}
bool is_base64_characters(Slice input) {
return is_base64_characters_impl<false>(input);
}
bool is_base64url_characters(Slice input) {
return is_base64_characters_impl<true>(input);
}
string base64_filter(Slice input) {
auto table = get_character_table<false>();
string res;
res.reserve(input.size());
for (auto c : input) {
if (table[static_cast<unsigned char>(c)] != 64 || c == '=') {
res += c;
}
}
return res;
}
} // namespace td