tdlight/tdutils/td/utils/tl_parsers.h

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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)
//
#pragma once
#include "td/utils/buffer.h"
#include "td/utils/common.h"
#include "td/utils/format.h"
#include "td/utils/logging.h"
#include "td/utils/Slice.h"
#include "td/utils/Status.h"
#include "td/utils/UInt.h"
#include "td/utils/utf8.h"
#include <array>
#include <cstring>
#include <limits>
#include <memory>
#include <string>
namespace td {
class TlParser {
const unsigned char *data = nullptr;
size_t data_len = 0;
size_t left_len = 0;
size_t error_pos = std::numeric_limits<size_t>::max();
std::string error;
std::unique_ptr<int32[]> data_buf;
static constexpr size_t SMALL_DATA_ARRAY_SIZE = 6;
std::array<int32, SMALL_DATA_ARRAY_SIZE> small_data_array;
alignas(4) static const unsigned char empty_data[sizeof(UInt256)];
public:
explicit TlParser(Slice slice);
TlParser(const TlParser &other) = delete;
TlParser &operator=(const TlParser &other) = delete;
void set_error(const string &error_message);
const char *get_error() const {
if (error.empty()) {
return nullptr;
}
return error.c_str();
}
size_t get_error_pos() const {
return error_pos;
}
Status get_status() const {
if (error.empty()) {
return Status::OK();
}
return Status::Error(PSLICE() << error << " at " << error_pos);
}
void check_len(const size_t len) {
if (unlikely(left_len < len)) {
set_error("Not enough data to read");
} else {
left_len -= len;
}
}
bool can_prefetch_int() const {
return get_left_len() >= sizeof(int32);
}
int32 prefetch_int_unsafe() const {
int32 result;
std::memcpy(&result, data, sizeof(int32));
return result;
}
int32 fetch_int_unsafe() {
int32 result;
std::memcpy(&result, data, sizeof(int32));
data += sizeof(int32);
return result;
}
int32 fetch_int() {
check_len(sizeof(int32));
return fetch_int_unsafe();
}
int64 fetch_long_unsafe() {
int64 result;
std::memcpy(&result, data, sizeof(int64));
data += sizeof(int64);
return result;
}
int64 fetch_long() {
check_len(sizeof(int64));
return fetch_long_unsafe();
}
double fetch_double_unsafe() {
double result;
std::memcpy(&result, data, sizeof(double));
data += sizeof(double);
return result;
}
double fetch_double() {
check_len(sizeof(double));
return fetch_double_unsafe();
}
template <class T>
T fetch_binary_unsafe() {
T result;
std::memcpy(&result, data, sizeof(T));
data += sizeof(T);
return result;
}
template <class T>
T fetch_binary() {
static_assert(sizeof(T) <= sizeof(empty_data), "too big fetch_binary");
//static_assert(sizeof(T) % sizeof(int32) == 0, "wrong call to fetch_binary");
check_len(sizeof(T));
return fetch_binary_unsafe<T>();
}
template <class T>
T fetch_string() {
check_len(sizeof(int32));
size_t result_len = *data;
const unsigned char *result_begin;
size_t result_aligned_len;
if (result_len < 254) {
result_begin = data + 1;
result_aligned_len = (result_len >> 2) << 2;
data += sizeof(int32);
} else if (result_len == 254) {
result_len = data[1] + (data[2] << 8) + (data[3] << 16);
result_begin = data + 4;
result_aligned_len = ((result_len + 3) >> 2) << 2;
data += sizeof(int32);
} else {
check_len(sizeof(int32));
auto result_len_uint64 = static_cast<uint64>(data[1]) + (static_cast<uint64>(data[2]) << 8) +
(static_cast<uint64>(data[3]) << 16) + (static_cast<uint64>(data[4]) << 24) +
(static_cast<uint64>(data[5]) << 32) + (static_cast<uint64>(data[6]) << 40) +
(static_cast<uint64>(data[7]) << 48);
if (result_len_uint64 > std::numeric_limits<size_t>::max() - 3) {
set_error("Too big string found");
return T();
}
result_len = static_cast<size_t>(result_len_uint64);
result_begin = data + 8;
result_aligned_len = ((result_len + 3) >> 2) << 2;
data += sizeof(int64);
}
check_len(result_aligned_len);
if (!error.empty()) {
return T();
}
data += result_aligned_len;
return T(reinterpret_cast<const char *>(result_begin), result_len);
}
template <class T>
T fetch_string_raw(const size_t size) {
//CHECK(size % sizeof(int32) == 0);
check_len(size);
if (!error.empty()) {
return T();
}
const char *result = reinterpret_cast<const char *>(data);
data += size;
return T(result, size);
}
void fetch_end() {
if (left_len) {
set_error("Too much data to fetch");
}
}
size_t get_left_len() const {
return left_len;
}
};
class TlBufferParser : public TlParser {
public:
explicit TlBufferParser(const BufferSlice *buffer_slice) : TlParser(buffer_slice->as_slice()), parent_(buffer_slice) {
}
template <class T>
T fetch_string() {
auto result = TlParser::fetch_string<T>();
for (auto &c : result) {
if (c == '\0') {
c = ' ';
}
}
if (check_utf8(result)) {
return result;
}
CHECK(!result.empty());
LOG(WARNING) << "Wrong UTF-8 string [[" << result << "]] in " << format::as_hex_dump<4>(parent_->as_slice());
// trying to remove last character
size_t new_size = result.size() - 1;
while (new_size != 0 && !is_utf8_character_first_code_unit(static_cast<unsigned char>(result[new_size]))) {
new_size--;
}
result.resize(new_size);
if (check_utf8(result)) {
return result;
}
return T();
}
template <class T>
T fetch_string_raw(const size_t size) {
return TlParser::fetch_string_raw<T>(size);
}
private:
const BufferSlice *parent_;
BufferSlice as_buffer_slice(Slice slice);
};
template <>
inline BufferSlice TlBufferParser::fetch_string<BufferSlice>() {
return as_buffer_slice(TlParser::fetch_string<Slice>());
}
template <>
inline BufferSlice TlBufferParser::fetch_string_raw<BufferSlice>(const size_t size) {
return as_buffer_slice(TlParser::fetch_string_raw<Slice>(size));
}
} // namespace td