NTP

NTP_sync

#include <cstdio>
#include <cstring>
#include <winsock2.h>
#include <ctime>

#include <iostream>
#include <string>
#pragma comment(lib, "ws2_32.lib")
using namespace std;
#define Years70 2208988800

class NTP
{
private:
	struct NTP_Packet 
	{
		int Control_Word;
		int root_delay;
		int root_dispersion;
		int reference_identifier;
		long long int reference_timestamp;
		long long int originate_timestamp;
		long long int receive_timestamp;
		int transmit_timestamp_seconds;
		int transmit_timestamp_fractions;
	};
	unsigned short server_port; // サーバのポート番号
	unsigned short get_port; // 受信するポート番号              
	WORD wSocketVersion;
	SOCKET udp_sock;
	struct sockaddr_in addr_udp;
	struct sockaddr_in addrServer;
	struct hostent* ser_hostent;
	struct NTP_Packet SendNtp;
	struct NTP_Packet recvNtpTime;
	struct timeval wait_time;
	fd_set rdps;
	int addr_size;
	int nError;
	int socks_ret;
	unsigned long ServerIP;
	time_t ntpTime;

public:
	string server_name;

	NTP();
	time_t getTime();
};

NTP::NTP() :server_port(123), get_port(1017), addr_udp({ 0 }), addrServer({ 0 }),
SendNtp({ htonl(0x0B000000) }), recvNtpTime({ 0 }), wait_time({ 0 })
{
	
}

time_t NTP::getTime()
{	
	WSADATA wsaData;
	if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0) return -1;

	{/* 初期化類 */
		addr_udp.sin_family = AF_INET;
		addr_udp.sin_port = htons(get_port);
		addr_udp.sin_addr.s_addr = INADDR_ANY;
		addr_size = sizeof(addrServer);

		ser_hostent = gethostbyname(server_name.c_str());
		ServerIP = *(unsigned long *)ser_hostent->h_addr_list[0];

		wait_time.tv_sec = 5; // タイムアウト時間
	}

	udp_sock = socket(PF_INET, SOCK_DGRAM, 0);
	if (udp_sock == INVALID_SOCKET) return -1;  
                 
	bind(udp_sock, (sockaddr *)&addr_udp, sizeof(addr_udp));

	addrServer.sin_family = AF_INET;								
	addrServer.sin_port = htons((unsigned short)server_port);       
	addrServer.sin_addr.s_addr = ServerIP;                          

	// サーバを指定して NTP パケットを送信する
	socks_ret = sendto(udp_sock, (const char *)&SendNtp, sizeof(SendNtp), 0, (struct sockaddr *)&addrServer, sizeof(addrServer));
	if (socks_ret == SOCKET_ERROR)
	{
		closesocket(udp_sock); return -1;          
	}
	FD_ZERO(&rdps); FD_SET(udp_sock, &rdps);
	socks_ret = select(FD_SETSIZE, &rdps, 0, 0, &wait_time);
	if (socks_ret == SOCKET_ERROR)
	{
		closesocket(udp_sock); return -1;        
	}
	if (socks_ret == 0)
	{
		closesocket(udp_sock); return -1;
	}
	if (FD_ISSET(udp_sock, &rdps) == FALSE)
	{
		closesocket(udp_sock); return -1;
	}

	socks_ret = recvfrom(udp_sock, (char *)&recvNtpTime, sizeof(recvNtpTime), 0, (struct sockaddr *)&addrServer, &addr_size);
	if (socks_ret == SOCKET_ERROR)
	{
		closesocket(udp_sock); return -1;
	}
	closesocket(udp_sock);
	WSACleanup();

	// UNIX 時間に変換
	ntpTime = ntohl(recvNtpTime.transmit_timestamp_seconds) - Years70;

	return ntpTime;
}

int main(void)
{
	time_t ntpTime = 0, localTime = 0;
	long diff = 0;
	tm *now;
	NTP ntp;
	char str[128] = { 0 };

	ntp.server_name = "ntp.nict.jp";

	for (int i = 0; i<3; i++)
	{
		memset(str, 0, sizeof(str));
		ntpTime = ntp.getTime(); 
			if (ntpTime == -1) return -1;
		now = localtime(&ntpTime);
		sprintf(str, "time %u:%u:%u", now->tm_hour, now->tm_min, now->tm_sec);
		system(str);
		Sleep(1000);
	}

	/*
		ntpTime = ntp.getTime();
		now = localtime(&ntpTime);
		memset(str, 0, sizeof(str));
		sprintf(str, "time %u:%u:%u", now->tm_hour, now->tm_min, now->tm_sec);
		system(str);
		Sleep(100);
	*/

	return 0;
}// Copyright (C) 2015 MAEKAWA TOSHIKI