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自写一个DNS解析库：示例和构建

前面的几篇文章已经把DNS解析库的框架、软件设计、类定义和接口实现等都介绍完成了，接下来我们需要更新一下库和代码的项目结构，以及构建编译、示例使用等。

目录更新​

根据前面的设计和实现我们更新目录树如下：

.
├── CMakeLists.txt
├── examples
│   └── dns_example.cpp
├── include
│   ├── async_resolver.h
│   ├── dns_packet.h
│   ├── dns_parser.h
│   └── dns_resolver.h
├── README.md
├── src
│   ├── async_resolver.cpp
│   ├── dns_packet.cpp
│   ├── dns_parser.cpp
│   └── dns_resolver.cpp
├── tests
│   ├── CMakeLists.txt
│   └── dns_test.cpp
├── ZJPDnsConfig.cmake.in
└── zjpdns.pc.in
  • CMakeLists.txt：构建的cmake
  • examples：使用库的示例程序
  • include：包含的头文件
    • async_resolver.h：异步解析器所在头文件
    • dns_packet.h：DNS包管理器所在头文件
    • dns_parser.h：DNS同步和异步解析器基类、创建同步和异步解析器接口所在头文件
    • dns_resolver.h：DNS同步和异步解析器实现类所在头文件
  • src：include对应源文件
  • tests：如果有更多的接口测试，可以放在这里
  • ZJPDnsConfig.cmake.in：是一个 CMake 包配置模板文件，用于支持其他项目通过 find_package() 命令来查找和使用这个DNS解析库
  • zjpdns.pc.in：pkg-config 包配置模板文件，用于支持基于 pkg-config 的依赖管理系统

构建​

我们来看下这个库的cmake该怎么写。

  • 我们希望能支持以静态库和动态库的方式进行编译，所以需要在cmake中设置选项；
  • 我们需要将编译生成的库和头文件支持安装到用户指定的位置；
  • 最好是支持自动传递编译依赖，在其他项目中使用的时候不需要写太多的语句去包含依赖
  • 导出目标，提供命名空间的保护
  • 支持pkg-config的依赖管理系统
  • 支持编译测试程序和示例程序

项目基础设置

cmake_minimum_required(VERSION 3.16)
  • 指定所需的最低CMake版本为3.16，确保使用的CMake功能兼容性
project(ZJPDnsParser VERSION 1.0.0 LANGUAGES CXX)
  • 定义项目名称为ZJPDnsParser，版本号1.0.0，使用C++语言

编译标准设置

set(CMAKE_CXX_STANDARD 17)
  • 设置C++标准为C++17
set(CMAKE_CXX_STANDARD_REQUIRED ON)
  • 强制要求使用指定的C++标准，如果编译器不支持则报错

构建选项

option(BUILD_SHARED_LIBS "Build shared libraries" ON)
option(BUILD_STATIC_LIBS "Build static libraries" ON)
  • 默认开启构建动态库(.so文件)
  • 默认开启构建静态库(.a文件)

文件定义

源文件

set(SOURCES
    src/dns_parser.cpp
    src/dns_packet.cpp
    src/dns_resolver.cpp
    src/async_resolver.cpp
)

头文件

set(HEADERS
    include/dns_parser.h
    include/dns_packet.h
    include/dns_resolver.h
    include/async_resolver.h
)

动态库构建

if(BUILD_SHARED_LIBS)
    add_library(zjpdns_shared SHARED ${SOURCES})
  • 如果启用动态库选项，创建名为zjpdns_shared的动态库目标
    set_target_properties(zjpdns_shared PROPERTIES
        OUTPUT_NAME zjpdns
        VERSION ${PROJECT_VERSION}
        SOVERSION ${PROJECT_VERSION_MAJOR}
    )

  • 设置动态库属性：

    • OUTPUT_NAME: 输出文件名为zjpdns，虽然目标名是 zjpdns_shared，但实际生成的文件名是 libzjpdns.so

    • VERSION: 完整版本号(1.0.0)，支持多版本共存

    • SOVERSION: 主版本号(1)，创建符号链接 libzjpdns.so.1 -> libzjpdns.so.1.0.0，程序运行时链接到 libzjpdns.so.1，在安装后会产生如下文件：

      /usr/local/lib/
      ├── libzjpdns.so -> libzjpdns.so.1        # 开发时链接
      ├── libzjpdns.so.1 -> libzjpdns.so.1.0.0  # 运行时链接  
      └── libzjpdns.so.1.0.0                    # 实际库文件
    target_include_directories(zjpdns_shared PUBLIC 
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> 
        $<INSTALL_INTERFACE:include>)
  • 设置包含目录：
    • 构建时使用${CMAKE_CURRENT_SOURCE_DIR}/include
    • 安装后使用include

静态库构建

同动态库

安装规则

install(TARGETS zjpdns_shared zjpdns_static
    EXPORT ZJPDnsTargets
    LIBRARY DESTINATION lib
    ARCHIVE DESTINATION lib
    RUNTIME DESTINATION bin
    INCLUDES DESTINATION include
)
  • 安装库文件：
    • EXPORT: 导出目标到ZJPDnsTargets
    • LIBRARY: 动态库安装到lib/
    • ARCHIVE: 静态库安装到lib/
    • RUNTIME: 运行时文件安装到bin/
    • INCLUDES: 包含目录设为include/
install(FILES ${HEADERS} DESTINATION include/zjpdns)
  • 安装头文件到include/zjpdns/目录

目标导出

install(EXPORT ZJPDnsTargets
    FILE ZJPDnsTargets.cmake
    NAMESPACE ZJPDns::
    DESTINATION lib/cmake/ZJPDns
)

  • 导出目标配置：

    • 生成ZJPDnsTargets.cmake文件
    • 添加命名空间ZJPDns::
    • 安装到lib/cmake/ZJPDns/

  • 其他项目可以这样使用

    # 其他项目的CMakeLists.txt
    find_package(ZJPDns REQUIRED)

    # 使用导出的目标
    target_link_libraries(my_app ZJPDns::zjpdns_shared)

包配置文件

include(CMakePackageConfigHelpers)
  • 包含CMake包配置助手模块
write_basic_package_version_file(
    ZJPDnsConfigVersion.cmake
    VERSION ${PROJECT_VERSION}
    COMPATIBILITY AnyNewerVersion
)
  • 生成版本兼容性检查文件，允许任何更新版本
configure_package_config_file(
    ZJPDnsConfig.cmake.in
    ZJPDnsConfig.cmake
    INSTALL_DESTINATION lib/cmake/ZJPDns
)
  • 从模板生成包配置文件
install(FILES
    ${CMAKE_CURRENT_BINARY_DIR}/ZJPDnsConfig.cmake
    ${CMAKE_CURRENT_BINARY_DIR}/ZJPDnsConfigVersion.cmake
    DESTINATION lib/cmake/ZJPDns
)
  • 安装生成的配置文件

pkg-config支持

configure_file(zjpdns.pc.in zjpdns.pc @ONLY)
  • 从模板生成pkg-config文件
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/zjpdns.pc DESTINATION lib/pkgconfig)
  • 安装pkg-config文件

示例程序编译

add_executable(dns_example examples/dns_example.cpp)
if(BUILD_SHARED_LIBS)
    target_link_libraries(dns_example zjpdns_shared)
else()
    target_link_libraries(dns_example zjpdns_static)
endif()
  • 链接库：优先使用动态库，否则使用静态库

测试支持

enable_testing()
  • 启用CMake测试功能
add_subdirectory(tests)
  • 添加测试子目录，处理tests/CMakeLists.txt

完整cmake​

cmake_minimum_required(VERSION 3.16)
project(ZJPDnsParser VERSION 1.0.0 LANGUAGES CXX)

# 设置C++标准
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# 编译选项
option(BUILD_SHARED_LIBS "Build shared libraries" ON)
option(BUILD_STATIC_LIBS "Build static libraries" ON)

# 源文件
set(SOURCES
    src/dns_parser.cpp
    src/dns_packet.cpp
    src/dns_resolver.cpp
    src/async_resolver.cpp
)

set(HEADERS
    include/dns_parser.h
    include/dns_packet.h
    include/dns_resolver.h
    include/async_resolver.h
)

# 创建库
if(BUILD_SHARED_LIBS)
    add_library(zjpdns_shared SHARED ${SOURCES})
    set_target_properties(zjpdns_shared PROPERTIES
        OUTPUT_NAME zjpdns
        VERSION ${PROJECT_VERSION}
        SOVERSION ${PROJECT_VERSION_MAJOR}
    )
    target_include_directories(zjpdns_shared PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>)
endif()

if(BUILD_STATIC_LIBS)
    add_library(zjpdns_static STATIC ${SOURCES})
    set_target_properties(zjpdns_static PROPERTIES
        OUTPUT_NAME zjpdns
    )
    target_include_directories(zjpdns_static PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>)
endif()

# 安装规则
install(TARGETS zjpdns_shared zjpdns_static
    EXPORT ZJPDnsTargets
    LIBRARY DESTINATION lib
    ARCHIVE DESTINATION lib
    RUNTIME DESTINATION bin
    INCLUDES DESTINATION include
)

install(FILES ${HEADERS} DESTINATION include/zjpdns)

# 导出目标
install(EXPORT ZJPDnsTargets
    FILE ZJPDnsTargets.cmake
    NAMESPACE ZJPDns::
    DESTINATION lib/cmake/ZJPDns
)

# 创建配置文件
include(CMakePackageConfigHelpers)
write_basic_package_version_file(
    ZJPDnsConfigVersion.cmake
    VERSION ${PROJECT_VERSION}
    COMPATIBILITY AnyNewerVersion
)

configure_package_config_file(
    ZJPDnsConfig.cmake.in
    ZJPDnsConfig.cmake
    INSTALL_DESTINATION lib/cmake/ZJPDns
)

install(FILES
    ${CMAKE_CURRENT_BINARY_DIR}/ZJPDnsConfig.cmake
    ${CMAKE_CURRENT_BINARY_DIR}/ZJPDnsConfigVersion.cmake
    DESTINATION lib/cmake/ZJPDns
)

# 创建pkg-config文件
configure_file(zjpdns.pc.in zjpdns.pc @ONLY)
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/zjpdns.pc DESTINATION lib/pkgconfig)

# 示例程序
add_executable(dns_example examples/dns_example.cpp)
if(BUILD_SHARED_LIBS)
    target_link_libraries(dns_example zjpdns_shared)
else()
    target_link_libraries(dns_example zjpdns_static)
endif()

# 测试
enable_testing()
add_subdirectory(tests)

pkg-config​

zjpdns.pc.in是一个 pkg-config 包配置模板文件，用于支持基于 pkg-config 的依赖管理系统。

主要功能

  1. pkg-config 支持: 允许其他项目通过 pkg-config 工具查找和链接库
  2. 编译参数提供: 自动提供正确的头文件路径和链接参数
  3. 跨平台兼容: 支持 Linux/Unix 系统的标准包管理方式
prefix=@CMAKE_INSTALL_PREFIX@        # 安装前缀路径（CMake变量替换）
exec_prefix=${prefix}                # 可执行文件前缀
includedir=${prefix}/include         # 头文件目录
libdir=${exec_prefix}/lib           # 库文件目录

Name: zjpdns                        # 包名称
Description: ZJP DNS Parser Library # 包描述
Version: @PROJECT_VERSION@          # 版本号（CMake变量替换）
Cflags: -I${includedir}            # 编译标志（头文件路径）
Libs: -L${libdir} -lzjpdns         # 链接标志（库路径和库名）

工作流程

  1. 构建时处理: CMakeLists.txt 中的 configure_file(zjpdns.pc.in zjpdns.pc @ONLY) 将模板转换为实际配置文件
  2. 安装: 生成的 zjpdns.pc 被安装到 lib/pkgconfig/ 目录
  3. 使用: 其他项目可以通过以下方式使用：
# 查询编译参数
pkg-config --cflags zjpdns
# 输出: -I/usr/local/include

# 查询链接参数  
pkg-config --libs zjpdns
# 输出: -L/usr/local/lib -lzjpdns

# 在Makefile中使用
CFLAGS += $(shell pkg-config --cflags zjpdns)
LDFLAGS += $(shell pkg-config --libs zjpdns)

与CMake配置的区别

  • ZJPDnsConfig.cmake.in: 现代CMake项目使用，通过 find_package() 集成
  • zjpdns.pc.in: 传统Unix/Linux项目使用，通过 pkg-config 工具集成

cmake.in​

ZJPDnsConfig.cmake.in 是一个 CMake 包配置模板文件，用于支持其他项目通过 find_package() 命令来查找和使用库。

主要功能

  1. 包配置模板: 这是一个模板文件，CMake 会在构建时将其处理成 ZJPDnsConfig.cmake
  2. 依赖管理: 允许其他项目轻松集成库
  3. 目标导入: 通过 ZJPDnsTargets.cmake 导入库的编译目标
@PACKAGE_INIT@                                    # CMake 宏，初始化包配置
include("${CMAKE_CURRENT_LIST_DIR}/ZJPDnsTargets.cmake")  # 导入库目标定义
check_required_components(ZJPDns)                 # 检查必需组件

工作流程

  1. 构建时处理: CMakeLists.txt 中的 configure_package_config_file() 将模板转换为实际配置文件
  2. 安装: 生成的 ZJPDnsConfig.cmake 被安装到 lib/cmake/ZJPDns/ 目录
  3. 使用: 其他项目可以通过以下方式使用：
find_package(ZJPDns REQUIRED)
target_link_libraries(my_app ZJPDns::zjpdns)

编译安装​

# 创建构建目录
mkdir build && cd build

# 配置编译选项
cmake .. -DCMAKE_BUILD_TYPE=Release

# 编译
make -j$(nproc)

# 安装
sudo make install

示例程序​

在示例程序中，展示了我们这个DNS解析库的各自使用方式：

#include "dns_parser.h"
#include <iostream>
#include <iomanip>
#include <chrono>
#include <thread>

void printResult(const zjpdns::DnsResult& result) {
    std::cout << "query domain: ";
    if (result.domains.empty()) {
        std::cout << "no domain";
    } else {
        for (size_t i = 0; i < result.domains.size(); ++i) {
            if (i > 0) std::cout << ", ";
            std::cout << result.domains[i];
        }
    }
    std::cout << std::endl;
    std::cout << "resolve success: " << (result.success ? "yes" : "no") << std::endl;
    
    if (!result.success) {
        std::cout << "error message: " << result.error_message << std::endl;
        return;
    }
    
    std::cout << "IP addresses:" << std::endl;
    for (const auto& addr : result.addresses) {
        std::cout << "  " << addr << std::endl;
    }
    
    std::cout << "DNS records:" << std::endl;
    for (const auto& record : result.records) {
        std::cout << "  name: " << record.name << std::endl;
        std::cout << "  type: " << static_cast<int>(record.type) << std::endl;
        std::cout << "  class: " << static_cast<int>(record.class_) << std::endl;
        std::cout << "  TTL: " << record.ttl << std::endl;
        std::cout << "  data length: " << record.data.length() << std::endl;
        std::cout << "  ---" << std::endl;
    }
    std::cout << std::endl;
}

int main() {
    std::cout << "=== ZJP DNS parser example ===" << std::endl;
    
    // 创建同步解析器
    auto resolver = zjpdns::createDnsResolver();
    
    // 设置DNS服务器和超时
    resolver->setDnsServer("8.8.8.8", 53);
    resolver->setTimeout(5000);
    
    std::vector<std::string> domains = {
        "www.google.com",
        "www.baidu.com",
        "www.github.com"
    };
    
    // 测试同步解析
    std::cout << "=== sync resolve test ===" << std::endl;
    for (const auto& domain : domains) {
        std::cout << "resolve domain: " << domain << std::endl;
        
        // 使用gethostbyname方式
        auto result1 = resolver->resolve(domain, zjpdns::DnsRecordType::A, 
                                       zjpdns::ResolveMethod::GETHOSTBYNAME);
        std::cout << "gethostbyname method:" << std::endl;
        printResult(result1);
        
        // 使用DNS数据包方式
        auto result2 = resolver->resolve(domain, zjpdns::DnsRecordType::A, 
                                       zjpdns::ResolveMethod::DNS_PACKET);
        std::cout << "DNS packet method:" << std::endl;
        printResult(result2);
    }
    
    // 测试自定义DNS数据包
    std::cout << "=== custom DNS packet test ===" << std::endl;
    zjpdns::DnsPacket custom_packet;
    custom_packet.id = 12345;
    custom_packet.flags = 0x0100; // 标准查询
    custom_packet.qdcount = 1;
    custom_packet.questions.push_back("www.example.com");
    
    auto result3 = resolver->resolveWithPacket(custom_packet);
    std::cout << "custom DNS packet resolve:" << std::endl;
    printResult(result3);
    
    // 测试异步解析
    std::cout << "=== async resolve test ===" << std::endl;
    auto async_resolver = zjpdns::createAsyncDnsResolver();
    async_resolver->setDnsServer("8.8.8.8", 53);
    async_resolver->setTimeout(5000);
    
    std::vector<std::future<zjpdns::DnsResult>> futures;
    
    // 异步解析 使用默认DNS数据包方式
    for (const auto& domain : domains) {
        auto future = async_resolver->resolveAsync(domain, zjpdns::DnsRecordType::A, 
                                                 zjpdns::ResolveMethod::DNS_PACKET);
        futures.push_back(std::move(future));
    }
    
    // 等待所有解析完成
    for (size_t i = 0; i < futures.size(); ++i) {
        auto result = futures[i].get();
        std::cout << "async resolve " << domains[i] << ":" << std::endl;
        printResult(result);
    }

    // 测试gethostbyname异步解析
    std::cout << "=== gethostbyname async resolve test ===" << std::endl;
    auto gethostbyname_future = async_resolver->resolveAsync("www.google.com", zjpdns::DnsRecordType::A,
                                                            zjpdns::ResolveMethod::GETHOSTBYNAME);
    auto gethostbyname_result = gethostbyname_future.get();
    std::cout << "gethostbyname async resolve result:" << std::endl;
    printResult(gethostbyname_result);

    // 测试自定义数据包异步解析
    std::cout << "=== custom DNS packet async resolve test ===" << std::endl;
    auto custom_packet_future = async_resolver->resolveWithPacketAsync(custom_packet);
    auto custom_packet_result = custom_packet_future.get();
    std::cout << "custom DNS packet async resolve result:" << std::endl;
    printResult(custom_packet_result);

    // 测试默认DNS数据包回调式异步解析
    std::cout << "=== callback async resolve test ===" << std::endl;
    std::atomic<int> completed_count{0};
    int total_count = domains.size();
    
    for (const auto& domain : domains) {
        async_resolver->resolveWithCallback(domain, 
            [&completed_count, total_count](const zjpdns::DnsResult& result) {
                std::cout << "callback async resolve completed: ";
                if (!result.domains.empty()) {
                    std::cout << result.domains[0];
                } else {
                    std::cout << "no domain";
                }
                std::cout << std::endl;
                printResult(result);
                completed_count++;
                
                if (completed_count >= total_count) {
                    std::cout << "all callback async resolve completed!" << std::endl;
                }
            },
            zjpdns::DnsRecordType::A,
            zjpdns::ResolveMethod::DNS_PACKET);
    }
    
    // 等待回调完成
    while (completed_count < total_count) {
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }

    // 测试gethostbyname回调式异步解析
    std::cout << "=== gethostbyname callback async resolve test ===" << std::endl;
    completed_count.store(0);
    for (const auto& domain : domains) {
        async_resolver->resolveWithCallback(domain, 
            [&completed_count, total_count](const zjpdns::DnsResult& result) {
                std::cout << "callback async resolve completed: ";
                if (!result.domains.empty()) {
                    std::cout << result.domains[0];
                } else {
                    std::cout << "no domain";
                }
                std::cout << std::endl;
                printResult(result);
                completed_count++;
                
                if (completed_count >= total_count) {
                    std::cout << "all callback async resolve completed!" << std::endl;
                }
            },
            zjpdns::DnsRecordType::A,
            zjpdns::ResolveMethod::GETHOSTBYNAME);
    }

    while (completed_count < total_count) {
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }
    
    // 测试自定义数据包回调式异步解析
    std::cout << "=== test custom DNS packet callback async resolve ===" << std::endl;
    zjpdns::DnsPacket custom_packet2;
    custom_packet2.id = 54321;
    custom_packet2.flags = 0x0100; // 标准查询
    custom_packet2.qdcount = 1;
    custom_packet2.questions.push_back("www.example.com");
    
    std::atomic<bool> packet_callback_called{false};
    async_resolver->resolveWithPacketCallback(custom_packet2,
        [&packet_callback_called](const zjpdns::DnsResult& result) {
            std::cout << "custom DNS packet callback async resolve completed: ";
            if (!result.domains.empty()) {
                std::cout << result.domains[0];
            } else {
                std::cout << "no domain";
            }
            std::cout << std::endl;
            printResult(result);
            packet_callback_called = true;
        });
    
    // 等待自定义数据包回调完成
    while (!packet_callback_called) {
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }
    
    std::cout << "=== test completed ===" << std::endl;
    return 0;
}

同步解析：

  • auto resolver = zjpdns::createDnsResolver();创建DNS同步解析器
  • 设置DNS服务器地址和超时时间
  • domian这个vector包含了我们待解析的域名
  • 调用resolver->resolve(domain, zjpdns::DnsRecordType::A,zjpdns::ResolveMethod::GETHOSTBYNAME);进行同步的gethostbyname解析
  • printResult打印解析结果
  • resolver->resolve(domain, zjpdns::DnsRecordType::A,zjpdns::ResolveMethod::DNS_PACKET);使用默认DNS数据包方式解析
  • 自定义数据包同步解析

异步解析：

  • auto async_resolver = zjpdns::createAsyncDnsResolver();创建异步解析器
  • 设置DNS服务器地址和超时时间
  • ....

在前面cmake编译安装的基础上，我们会在build目录下找到dns_examples，执行它会看到如下输出：

=== ZJP DNS parser example ===
=== sync resolve test ===
resolve domain: www.google.com
gethostbyname method:
query domain: www.google.com
resolve success: yes
IP addresses:
  31.13.73.9
DNS records:
  name: www.google.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

DNS packet method:
query domain: www.google.com.
resolve success: yes
IP addresses:
  31.13.94.10
DNS records:
  name: www.google.com.
  type: 1
  class: 1
  TTL: 101
  data length: 4
  ---

resolve domain: www.baidu.com
gethostbyname method:
query domain: www.baidu.com
resolve success: yes
IP addresses:
  183.240.99.58
  183.240.99.169
DNS records:
  name: www.baidu.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---
  name: www.baidu.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

DNS packet method:
query domain: www.baidu.com.
resolve success: yes
IP addresses:
  103.235.46.102
  103.235.46.115
DNS records:
  name: www.baidu.com.
  type: 5
  class: 1
  TTL: 910
  data length: 15
  ---
  name: www.a.shifen.com.
  type: 5
  class: 1
  TTL: 22
  data length: 14
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 292
  data length: 4
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 292
  data length: 4
  ---

resolve domain: www.github.com
gethostbyname method:
query domain: www.github.com
resolve success: yes
IP addresses:
  20.205.243.166
DNS records:
  name: www.github.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

DNS packet method:
query domain: www.github.com.
resolve success: yes
IP addresses:
  20.205.243.166
DNS records:
  name: www.github.com.
  type: 5
  class: 1
  TTL: 3598
  data length: 2
  ---
  name: github.com.
  type: 1
  class: 1
  TTL: 60
  data length: 4
  ---

=== custom DNS packet test ===
custom DNS packet resolve:
query domain: www.example.com.
resolve success: yes
IP addresses:
  104.84.150.196
  104.84.150.167
DNS records:
  name: www.example.com.
  type: 5
  class: 1
  TTL: 34
  data length: 34
  ---
  name: www.example.com-v4.edgesuite.net.
  type: 5
  class: 1
  TTL: 15233
  data length: 20
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---

=== async resolve test ===
async resolve www.google.com:
query domain: www.google.com.
resolve success: yes
IP addresses:
  31.13.88.169
DNS records:
  name: www.google.com.
  type: 1
  class: 1
  TTL: 97
  data length: 4
  ---

async resolve www.baidu.com:
query domain: www.baidu.com.
resolve success: yes
IP addresses:
  103.235.46.102
  103.235.46.115
DNS records:
  name: www.baidu.com.
  type: 5
  class: 1
  TTL: 910
  data length: 15
  ---
  name: www.a.shifen.com.
  type: 5
  class: 1
  TTL: 22
  data length: 14
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 292
  data length: 4
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 292
  data length: 4
  ---

async resolve www.github.com:
query domain: www.github.com.
resolve success: yes
IP addresses:
  20.205.243.166
DNS records:
  name: www.github.com.
  type: 5
  class: 1
  TTL: 3573
  data length: 2
  ---
  name: github.com.
  type: 1
  class: 1
  TTL: 38
  data length: 4
  ---

=== gethostbyname async resolve test ===
gethostbyname async resolve result:
query domain: www.google.com
resolve success: yes
IP addresses:
  31.13.73.9
DNS records:
  name: www.google.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

=== custom DNS packet async resolve test ===
custom DNS packet async resolve result:
query domain: www.example.com.
resolve success: yes
IP addresses:
  104.84.150.196
  104.84.150.167
DNS records:
  name: www.example.com.
  type: 5
  class: 1
  TTL: 114
  data length: 34
  ---
  name: www.example.com-v4.edgesuite.net.
  type: 5
  class: 1
  TTL: 21104
  data length: 20
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---

=== callback async resolve test ===
callback async resolve completed: www.google.com.
query domain: www.google.com.
resolve success: yes
IP addresses:
  199.16.158.8
DNS records:
  name: www.google.com.
  type: 1
  class: 1
  TTL: 172
  data length: 4
  ---

callback async resolve completed: www.baidu.com.
query domain: www.baidu.com.
resolve success: yes
IP addresses:
  103.235.46.102
  103.235.46.115
DNS records:
  name: www.baidu.com.
  type: 5
  class: 1
  TTL: 1159
  data length: 15
  ---
  name: www.a.shifen.com.
  type: 5
  class: 1
  TTL: 18
  data length: 14
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 104
  data length: 4
  ---
  name: www.wshifen.com.
  type: 1
  class: 1
  TTL: 104
  data length: 4
  ---

callback async resolve completed: www.github.com.
query domain: www.github.com.
resolve success: yes
IP addresses:
  20.205.243.166
DNS records:
  name: www.github.com.
  type: 5
  class: 1
  TTL: 3573
  data length: 2
  ---
  name: github.com.
  type: 1
  class: 1
  TTL: 38
  data length: 4
  ---

all callback async resolve completed!
=== gethostbyname callback async resolve test ===
callback async resolve completed: www.google.com
query domain: www.google.com
resolve success: yes
IP addresses:
  31.13.73.9
DNS records:
  name: www.google.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

callback async resolve completed: www.baidu.com
query domain: www.baidu.com
resolve success: yes
IP addresses:
  183.240.99.169
  183.240.99.58
DNS records:
  name: www.baidu.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---
  name: www.baidu.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

callback async resolve completed: www.github.com
query domain: www.github.com
resolve success: yes
IP addresses:
  20.205.243.166
DNS records:
  name: www.github.com
  type: 1
  class: 1
  TTL: 300
  data length: 4
  ---

all callback async resolve completed!
=== test custom DNS packet callback async resolve ===
custom DNS packet callback async resolve completed: www.example.com.
query domain: www.example.com.
resolve success: yes
IP addresses:
  104.84.150.196
  104.84.150.167
DNS records:
  name: www.example.com.
  type: 5
  class: 1
  TTL: 144
  data length: 34
  ---
  name: www.example.com-v4.edgesuite.net.
  type: 5
  class: 1
  TTL: 17185
  data length: 20
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---
  name: a1422.dscr.akamai.net.
  type: 1
  class: 1
  TTL: 20
  data length: 4
  ---

=== test completed ===

自写DNS解析库系列完结。