使用boost解析域名服务

下面的源码给出了使用boost::asio进行域名解析的方法.

//g++ -g resolver_demo.cpp -o resolver_demo -lboost_system -lpthread
//

#include <iostream>
#include <boost/asio.hpp>
#include <boost/system/error_code.hpp>
#include <boost/lexical_cast.hpp>

using namespace std;
using namespace boost::asio;

void resolv_connect(io_service& ios, ip::tcp::socket& sock, const char* host, int port){
    ip::tcp::resolver rslv(ios);
    ip::tcp::resolver::query qry(host, boost::lexical_cast<string>(port));
    cout << "host_name: " << qry.host_name() << ", service_name: " << qry.service_name() << endl;

    ip::tcp::resolver::iterator iter = rslv.resolve(qry);
    ip::tcp::resolver::iterator end;
    boost::system::error_code ec = error::host_not_found;

    for( ; ec&&iter!=end; ++iter){
        sock.close();
        sock.connect(*iter, ec);
    }

    if(ec){
        cout << "cannot connect" << endl;
        throw boost::system::system_error(ec);
    }
    else if(iter != end){
        ip::tcp::endpoint endpoint = iter->endpoint();
        cout << "query success!" << endl;
        cout << "host_ip: " << endpoint.address() << ", port: " << endpoint.port() << endl;
    }
    else
        return;
}

int main(){
    try{
        io_service ios;
        ip::tcp::socket sock(ios);
        resolv_connect(ios, sock, "news.sohu.com", 80);
    }
    catch(exception& e){
        cerr << e.what() << endl;
        return 1;
    }

    return 0;
}

下面是运行截图