C++ POCO库中文编程参考指南（9） Poco::Net::DNS

1 Poco::Net::DNS

namespace Poco {   
namespace Net {   
class Net_API DNS {   
public:   
    static HostEntry hostByName(const std::string& hostname);   
    static HostEntry hostByAddress(const IPAddress& address);   
    static HostEntry resolve(const std::string& address);   
    static IPAddress resolveOne(const std::string& address);   
    static HostEntry thisHost();   
    static std::string hostName();   
};   
}   
}

HostEntry 中存储 host primary name（canonical name）、alias name list、IP address list。

2 相关 API

获得一个 HostEntry 实 例：

const HostEntry& entry = DNS::hostByName ("google.com");

输出域名：

std::cout << entry.name() << std::endl;

Address 和 Alias：

const HostEntry::AliasList& aliases = entry.aliases();

const HostEntry::AddressList& addrs = entry.addresses();

3 Source code

POCO 的官方文档中的 Sample 有错误，以下提供一个正确的示例， 个中域名是通过参数传入的。

#include "Poco/Net/DNS.h"   
#include <iostream>   
using Poco::Net::DNS;   
using Poco::Net::IPAddress;   
using Poco::Net::HostEntry;   
int main(int argc, char** argv)   
{   
    if (argc != 2) {   
        std::cout << "Invalid argument number." << 

std::endl;   
    }   
    const HostEntry& entry = DNS::hostByName(argv[1]);   
    std::cout << "Canonical Name: " << entry.name() 

<< std::endl;   

    const HostEntry::AliasList& aliases = entry.aliases();   
    for (HostEntry::AliasList::const_iterator it = aliases.begin();   
        it !=   aliases.end(); ++it)   
        std::cout << "Alias: " << *it << std::endl;  

    const HostEntry::AddressList& addrs = entry.addresses();   
    for (HostEntry::AddressList::const_iterator it = addrs.begin();   
        it !=   addrs.end(); ++it)   
        std::cout << "Address: " << it->toString() 

<< std::endl;   

    return 0;   
}

编译：

$ g++ name_solver.cpp -o name_solver \

-I/usr/local/include -I/usr/local/lib -lPocoNet

运行：

$ ./name_solver baidu.com   
Canonical Name: baidu.com   
Address: 123.125.114.144   
Address: 123.125.114.144   
Address: 220.181.111.85   
Address: 220.181.111.85   
Address: 220.181.111.86   
Address: 220.181.111.86   

$ ./name_solver www.ustc.edu.cn   
Canonical Name: ustc.edu.cn   
Address: 202.38.64.246   
Address: 202.38.64.246

来自柳大的CSDN博客： Blog.CSDN.net/Poechant

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