#!/usr/bin/env python
# coding: utf8
# Usage: 指定ntpserver域名到ntpserver_domains变量即可

import socket
import struct
import time
import win32api
import subprocess
import os
import sys



def gettime(ntpserver_ips):
    TIME_1970 = 2208988800L
    client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    client.settimeout(3)
    data = '\x1b' + 47 * '\0'
    Port=123
    
    for server in ntpserver_ips:
        success = False
        count = 1
        '''每个ip尝试3次'''
        while not success and count < 4:
            try:
                client.sendto(data, (server, Port))
                data = client.recvfrom(1024)[0]
                success = True
                print server+' get time success, tried '+str(count)+' times.'
            except socket.timeout:
                print server+' get time failed, tried '+str(count)+' times.'
                count += 1
                
        if success == True:
            break
            
    data_result = struct.unpack('!12I', data)[10]
    data_result -= TIME_1970
    return data_result
    

def settime(nowtime):
    tm_year, tm_mon, tm_mday, tm_hour, tm_min, tm_sec, tm_wday, tm_yday, tm_isdst = time.gmtime(nowtime)
    win32api.SetSystemTime(tm_year, tm_mon, tm_wday, tm_mday, tm_hour, tm_min, tm_sec, 0)
    print u'Set system time success.'


def getip_with_domains(ntpserver_domains):
    ips = []
    for i in ntpserver_domains:
        ip = socket.gethostbyname_ex(i)[2]
        ips.extend(ip)
    return ips

    

if __name__ == '__main__':
    ntpserver_domains = ['cn.pool.ntp.org', 'ntp.sjtu.edu.cn', 'time.windows.com']
    ntpserver_ips = getip_with_domains(ntpserver_domains)
    if not ntpserver_ips or len(ntpserver_ips) != len(set(ntpserver_ips)):
        print u'Some domain can not resolve ip.'
        print os.system('pause')
        sys.exit()
    else:
        nowtime = gettime(ntpserver_ips)
        settime(nowtime)
        print u'Now Time：',time.strftime('%Y-%m-%d %X')
        os.system('pause')