因为上次那个获取网络时间失效了（使用的是37端口），获取网络时间并刷新本地时间（源码1）

所以网上又找了一份代码，使用的是123端口，虽然没有测试成功，这里也做下记录，估计是本机环境问题，过两天再进行测试一下。

// getNTPTime.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

using namespace std;

  
char *GetHostIP(char *strHost)  
{  
	char *strIP = NULL;
    PHOSTENT hostinfo = gethostbyname(strHost);  
    if(hostinfo != NULL)  
    {  
        strIP = inet_ntoa(*(struct in_addr *)*hostinfo->h_addr_list);  
    }  
    return strIP;  
}  

BOOL SetTimeout(SOCKET s, int nTime, BOOL bRecv)   
{   
    int ret = ::setsockopt(s, SOL_SOCKET, bRecv ? SO_RCVTIMEO : SO_SNDTIMEO, (char *)&nTime, sizeof(nTime));   
    return ret != SOCKET_ERROR;   
}   

  
time_t getSNTPTime()  
{  
	WSADATA wsa; 
	WORD wVersionRequested; 
	wVersionRequested = MAKEWORD(2, 0);  
	if (WSAStartup(wVersionRequested , &wsa)!=0) 
	{ 
		cerr << "--->>> Winsock Initialization failed." << endl;
	}

	time_t t = 0;
    vector<char *> vecTimeSvr;  

	vecTimeSvr.push_back("ntp1.aliyun.com");
	vecTimeSvr.push_back("ntp2.aliyun.com");
	vecTimeSvr.push_back("ntp3.aliyun.com");
	vecTimeSvr.push_back("ntp4.aliyun.com");
	vecTimeSvr.push_back("ntp5.aliyun.com");
	vecTimeSvr.push_back("ntp6.aliyun.com");
	vecTimeSvr.push_back("ntp7.aliyun.com");

	/*
    vecTimeSvr.push_back("cn.pool.ntp.org");  
    vecTimeSvr.push_back("0.cn.pool.ntp.org");  
    vecTimeSvr.push_back("1.cn.pool.ntp.org");  
    vecTimeSvr.push_back("2.cn.pool.ntp.org");  
    vecTimeSvr.push_back("3.cn.pool.ntp.org");  
    vecTimeSvr.push_back("time.windows.com"); 

	/*	//开放本段，可以在列表中添加更多的NTP服务器
    vecTimeSvr.push_back("pool.ntp.org");  
    vecTimeSvr.push_back("north-america.pool.ntp.org");  
    vecTimeSvr.push_back("south-america.pool.ntp.org");  
    vecTimeSvr.push_back("africa.pool.ntp.org");  
    vecTimeSvr.push_back("ca.pool.ntp.org");  
    vecTimeSvr.push_back("uk.pool.ntp.org");  
    vecTimeSvr.push_back("us.pool.ntp.org");  
    vecTimeSvr.push_back("au.pool.ntp.org");  
    vecTimeSvr.push_back("time.nist.gov");  
    vecTimeSvr.push_back("time-nw.nist.gov");  
    vecTimeSvr.push_back("europe.pool.ntp.org");  
    vecTimeSvr.push_back("asia.pool.ntp.org");  
    vecTimeSvr.push_back("oceania.pool.ntp.org");  



	*/
  
	SYSTEMTIME systime;
    for(size_t i = 0; i < vecTimeSvr.size(); ++i)  
    {  
        char *strHostName = vecTimeSvr[i];  
        char *strIP = GetHostIP(strHostName);  
  
        int SIZE_SOCKADDR_IN = sizeof(SOCKADDR_IN);  
        sockaddr_in SvrIp;  
        SvrIp.sin_family        = AF_INET;  
        SvrIp.sin_addr.s_addr   = inet_addr(strIP);  
        SvrIp.sin_port          = htons(37);  
  
        int nLenRcv = 0;  
        char szBuff[48] = {'\0'};  
        szBuff[0] = 3 | (4 << 3);  
        SOCKET sSession = ::socket(AF_INET, SOCK_DGRAM, 0);  
        SetTimeout(sSession, 6000, FALSE);  
        if(SOCKET_ERROR != sendto(sSession, szBuff, 48, 0, (sockaddr*)&SvrIp, SIZE_SOCKADDR_IN))  
        {  
            SetTimeout(sSession, 6000, TRUE);  
            nLenRcv = recvfrom(sSession, szBuff, 48, 0, (sockaddr*)&SvrIp, &SIZE_SOCKADDR_IN);  
        }  
        else  
        {  
			cerr << "--->>> " << strHostName << ": " << strIP <<endl;  
            cerr << "--->>> send SNTP request failed!" << endl;  
        }  
        closesocket(sSession);  
  
        if(nLenRcv == 48)  
        {  
            t = 0;  
            for(int i = 40; i <= 43; i++)  
            {  
                unsigned char c = (unsigned char)szBuff[i];  
                t = (t<<8) | c;  
            }  
  
            tm _t;
            t -= 2208988800L;    // 1970.1.1 0:0:0  - 1900.1.1 0:0:0  
 			localtime_s(&_t, &t);  
            cerr << "--->>> SNTP's Time - " << (_t.tm_year + 1900) << "-" << (_t.tm_mon + 1) << "-" << (_t.tm_mday) << " " << _t.tm_hour << ":" << _t.tm_min << ":" << _t.tm_sec << endl;  
			cerr << "--->>> " << strHostName << ": " << strIP <<endl;  
			cerr << endl;
			systime.wYear = _t.tm_year +1900;
			systime.wMonth = _t.tm_mon + 1;
			systime.wDay = _t.tm_mday;
			systime.wHour = _t.tm_hour;
			systime.wMinute = _t.tm_min;
			systime.wSecond = _t.tm_sec;
			systime.wMilliseconds = 0;
			systime.wDayOfWeek = -1;
			SetLocalTime(&systime);
			break;
        }  
    }  
	if (t == 0)
	{
        cerr << "--->>> recieve all SNTP's time is failed!" << endl;  
	}
    return t;  
}  


int _tmain(int argc, _TCHAR* argv[])
{
	time_t t_1 = getSNTPTime();
	if (t_1 > 0)
	{
		char strTime[50];
		ctime_s(strTime, sizeof(strTime), &t_1);
		cerr << "--->>> now is " << strTime << endl;
	}
	cerr << endl;
	system("pause");
	return 0;
}