108 lines
2.6 KiB
C++
108 lines
2.6 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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#pragma once
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#include <cassert>
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#include <cstdint>
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#include <cstring>
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#include <string>
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namespace td {
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namespace tl {
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class tl_simple_parser {
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const char *data;
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const char *data_begin;
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std::size_t data_len;
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const char *error;
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std::size_t error_pos;
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void set_error(const char *error_message) {
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if (error == NULL) {
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assert(error_message != NULL);
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error = error_message;
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error_pos = static_cast<std::size_t>(data - data_begin);
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data = "\x00\x00\x00\x00\x00\x00\x00\x00";
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data_len = 0;
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} else {
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data = "\x00\x00\x00\x00\x00\x00\x00\x00";
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assert(data_len == 0);
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}
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}
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void check_len(const std::size_t len) {
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if (data_len < len) {
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set_error("Not enough data to read");
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} else {
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data_len -= len;
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}
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}
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tl_simple_parser(const tl_simple_parser &other);
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tl_simple_parser &operator=(const tl_simple_parser &other);
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public:
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tl_simple_parser(const char *data, std::size_t data_len)
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: data(data), data_begin(data), data_len(data_len), error(), error_pos() {
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}
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const char *get_error() const {
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return error;
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}
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std::size_t get_error_pos() const {
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return error_pos;
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}
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std::int32_t fetch_int() {
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check_len(sizeof(std::int32_t));
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std::int32_t result = *reinterpret_cast<const std::int32_t *>(data);
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data += sizeof(std::int32_t);
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return result;
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}
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std::int64_t fetch_long() {
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check_len(sizeof(std::int64_t));
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std::int64_t result;
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std::memcpy(&result, data, sizeof(std::int64_t));
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data += sizeof(std::int64_t);
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return result;
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}
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std::string fetch_string() {
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check_len(4);
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int result_len = static_cast<unsigned char>(data[0]);
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if (result_len < 254) {
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check_len((result_len >> 2) * 4);
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std::string result(data + 1, result_len);
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data += ((result_len >> 2) + 1) * 4;
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return result;
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}
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if (result_len == 254) {
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result_len = static_cast<unsigned char>(data[1]) + (static_cast<unsigned char>(data[2]) << 8) +
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(static_cast<unsigned char>(data[3]) << 16);
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check_len(((result_len + 3) >> 2) * 4);
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std::string result(data + 4, result_len);
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data += ((result_len + 7) >> 2) * 4;
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return result;
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}
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set_error("Can't fetch string, 255 found");
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return std::string();
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}
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void fetch_end() {
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if (data_len) {
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set_error("Too much data to fetch");
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}
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}
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};
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} // namespace tl
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} // namespace td
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