get correct unix timestamp from ntp server

ntptime.py

"""
Original source:
https://www.mattcrampton.com/blog/query_an_ntp_server_from_python/
"""

from socket import AF_INET, SOCK_DGRAM
import socket
import struct


def get_unixtime(host="in.pool.ntp.org"):
    port = 123
    buf = 1024
    address = (host, port)
    msg = '\x1b' + 47 * '\0'
    
    # reference time (in seconds since 1900-01-01 00:00:00)
    TIME1970 = 2208988800  # 1970-01-01 00:00:00
    
    # connect to server
    client = socket.socket(AF_INET, SOCK_DGRAM)
    client.sendto(msg.encode('utf-8'), address)
    msg, address = client.recvfrom(buf)
    
    t = struct.unpack("!12I", msg)[10]
    t -= TIME1970
    return t


def test_get_unixtime():
    import datetime as dt
    ntptime = get_unixtime()
    localtime = dt.datetime.timestamp(dt.datetime.now())
    print(ntptime, localtime, localtime-ntptime)


if __name__ == "__main__":
    test_get_unixtime()