C++从NTP服务器取时间、转本地时间(Windows)

#include <iostream>
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#define WIN32_MEAN_AND_LEAN

#include <winsock2.h>
#include <windows.h>

#include <time.h>
#pragma comment(lib,"ws2_32.lib")    //Winsock Library

using namespace std;

class HRException{
public:
    HRException() :
        m_pMessage("") {}
    virtual ~HRException() {}
    HRException(const char *pMessage) :
        m_pMessage(pMessage) {}
    const char * what() { return m_pMessage; }
private:
    const char *m_pMessage;
};

const int  REQ_WINSOCK_VER   = 2; // Minimum winsock version required
const char DEF_SERVER_NAME[] = "0.pl.pool.ntp.org";
const int  SERVER_PORT       = 123;
const int  REC_BUFFER_SIZE   = 128;

const char msg[48] = { 010,0,0,0,0,0,0,0,0 };

// IP number typedef for IPv4
typedef unsigned long IPNumber;

IPNumber FindHostIP(const char *pServerName){
    HOSTENT *pHostent;

    // Get hostent structure for hostname:
    if (!(pHostent = gethostbyname(pServerName)))
        throw HRException("could not resolve hostname.");

    // Extract primary IP address from hostent structure:
    if (pHostent->h_addr_list && pHostent->h_addr_list[0])
        return *reinterpret_cast<IPNumber*>(pHostent->h_addr_list[0]);

    return 0;
}

void FillSockAddr(sockaddr_in *pSockAddr, const char *pServerName, int portNumber){
    // Set family, port and find IP
    pSockAddr->sin_family = AF_INET;
    pSockAddr->sin_port = htons(portNumber);
    pSockAddr->sin_addr.S_un.S_addr = FindHostIP(pServerName);
}

bool RequestHeaders(const char *pServername){
    int slen=0;
    time_t timeRecv; struct tm *tim;
    SOCKET      hSocket = INVALID_SOCKET;
    char        recvBuf[REC_BUFFER_SIZE];
    sockaddr_in sockAddr = { 0 };
    bool        bSuccess = true;

    try{
        // Lookup hostname and fill sockaddr_in structure:
        FillSockAddr(&sockAddr, pServername, SERVER_PORT);

        // Create socket
        if ((hSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == INVALID_SOCKET)
            throw HRException("could not create socket.");

        // Connect to server
        if (connect(hSocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr)) != 0)
            throw HRException("could not connect.");
        cout << "connected " << inet_ntoa(sockAddr.sin_addr) << ":" << SERVER_PORT << endl;

        // send request part 1
        if (send(hSocket, msg, sizeof(msg) , 0) == SOCKET_ERROR)
            throw HRException("failed to send data.");

        cout << "Dumping received data...\n\n";
        // Loop to print all data
        slen=recv(hSocket, recvBuf, REC_BUFFER_SIZE, 0); 
        //part where we take time out of recvBuf       
        timeRecv = ntohl(((time_t*)recvBuf)[4]);
        if(timeRecv>0)timeRecv-= 2208988800U;
        tim=localtime(&timeRecv);
        printf("%lld -> %d-%02d-%02d %02d:%02d:%02d\r\n",
            timeRecv, tim->tm_year+1900, tim->tm_mon+1, tim->tm_mday, tim->tm_hour, tim->tm_min, tim->tm_sec);
    }catch (HRException e){
        cerr << "\nError: " << e.what() << endl;
        bSuccess = false;
    }

    if (hSocket != INVALID_SOCKET){
        closesocket(hSocket);
    }
    return bSuccess;
}

int main(int argc, char* argv[]){
    int iRet = 1;
    WSADATA wsaData;

    if (WSAStartup(MAKEWORD(REQ_WINSOCK_VER, 0), &wsaData) != 0){
        cerr << "startup failed!\n";
        return iRet;
    }
    // Check if major version is at least REQ_WINSOCK_VER
    if (LOBYTE(wsaData.wVersion) >= REQ_WINSOCK_VER){

        // Set default hostname:
        const char *pHostname = DEF_SERVER_NAME;
        // Set custom hostname if given on the commandline:
        if (argc > 1){
            pHostname = argv[1];
        }

        iRet = !RequestHeaders(pHostname);
    }else{
        cerr << "required winsocket version not supported!";
    }

    // Cleanup winsock
    if (WSACleanup() != 0){
        cerr << "cleanup failed!\n";
        iRet = 1;
    }

    return iRet;
}

---FROM stackoverflow, changed, add convert to localtime