Получить дату и время используя NTP

//
// snip from:
// [url]www.mydailyhacks.org/2014/11/14/get-the-ntp-time-in-c-programm-via-a-simple-socket[/url]
//
 
#include <iostream>
#include <winsock2.h>
#include <time.h>
#pragma comment(lib, "ws2_32.lib")
 
void ntpdate();
 
int main() {
 
    WSADATA wsaData;
    if( !WSAStartup(MAKEWORD(2,2),&wsaData) )
        ntpdate();
    return 0;
}
 
void ntpdate() {
 
    // can be any timing server
    // you might have to change the IP if the server is no longer available
    char *hostname=(char *)"200.20.186.76";
    
    // ntp uses port 123
    int portno=123;
    const int maxlen=1024;
    int i;
    // buffer for the socket request
    unsigned char msg[48]={010,0,0,0,0,0,0,0,0};
 
    // buffer for the reply
    unsigned long buf[maxlen];
    //struct in_addr ipaddr;
    struct protoent *proto; //
    struct sockaddr_in server_addr;
    int s; // socket
    long tmit; // the time -- This is a time_t sort of
 
    // open a UDP socket
    proto=getprotobyname("udp");
    s=socket(PF_INET, SOCK_DGRAM, proto->p_proto);
 
    //here you can convert hostname to ipaddress if needed
    //$ipaddr = inet_aton($HOSTNAME);
    
    memset( &server_addr, 0, sizeof( server_addr ));
    server_addr.sin_family=AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(hostname);
    server_addr.sin_port=htons(portno);
    
    /*
    * build a message. Our message is all zeros except for a one in the
    * protocol version field
    * msg[] in binary is 00 001 000 00000000
    * it should be a total of 48 bytes long
    */
    
    // send the data to the timing server
    i=sendto(s,(const char*)msg,sizeof(msg),0,(struct sockaddr *)&server_addr,sizeof(server_addr));
    //if( (sendto( sock, buff, size, 0, (struct sockaddr *)&host, sizeof(host))) != size )
    
    // get the data back
    struct sockaddr saddr;
    int fromlen = sizeof (saddr);
    // here we wait for the reply and fill it into our buffer
    i=recvfrom(s,(char*)buf,48,0,&saddr,&fromlen);
    
    // We get 12 long words back in Network order
    
    /*
    * The high word of transmit time is the 4th word we get back
    * tmit is the time in seconds not accounting for network delays which
    * should be way less than a second if this is a local NTP server
    */
    
    tmit=ntohl((time_t)buf[4]); //# get transmit time
    tmit-= 2208988800U;
    std::cout << "NTP time is " << ctime(&tmit) << std::endl;
    i=time(0);
    std::cout << "System time is " << (i-tmit) << " seconds off" << std::endl;
}