import socket
import struct, sys, time

# default server
host = "localhost"
port = 8037

# reference time (in seconds since 1900-01-01 00:00:00)
TIME1970 = 2208988800L # 1970-01-01 00:00:00

def gettime(host, port):
    # fetch time buffer from stream server
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((host, port))
    t = s.recv(4)
    s.close()
    t = struct.unpack("!I", t)[0]
    return int(t - TIME1970)

if __name__ == "__main__":
    # command line utility
    if sys.argv[1:]:
        host = sys.argv[1]
        if sys.argv[2:]:
            port = int(sys.argv[2])
        else:
            port = 37 # default for public servers

    t = gettime(host, port)
    print "server time is", time.ctime(t)
    print "local clock is", int(time.time()) - t, "seconds off"

## server time is Sat Oct 09 16:58:50 1999
## local clock is 0 seconds off