import usocket as socket
import ustruct as struct

# (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60
NTP_DELTA = 3155673600
NTP_PKT_LEN = 48
NTP_QUERY = '\x1b' + (NTP_PKT_LEN-1) * '\0'

def get_ntp_time(host = "pool.ntp.org"):
    addr = socket.getaddrinfo(host, 123)[0][-1]
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.SO_REUSEADDR)
    s.settimeout(2)
    # sending twice - it appears the first packet after connecting to the network does not get sent
    s.sendto(NTP_QUERY, addr)
    s.sendto(NTP_QUERY, addr)
    msg = s.recv(NTP_PKT_LEN)
    del s
    val = struct.unpack("!I", msg[40:44])[0]
    return val - NTP_DELTA