From: Colin Bartlett <colinb2r@...>
Date: 2010-01-24T00:11:58+09:00
Subject: Re: Get time object from the web?

On Sat, Jan 23, 2010 at 12:34 AM, Jose Wong <josevemon7@gmail.com> wrote:
> Great! It seems to work, but, can someone help me for making a class
> with that code, that will return that time object? Like this:
>   @now = ServerTime.get_time
> @now is now the time object returned by that server...

The following seems to work, but it *isn't* "production code"
because it doesn't deal with timeouts or other failures,
which should perhaps return nil or raise an exception.

# based on code at
http://juretta.com/log/2006/08/26/ruby_contacting_a_timeserver/
require "net/telnet"

class ServerTime
  attr_reader :host
  TIME_SERVER = 'ntp2.fau.de'
   # 25567 = 70 * 365 + 70.div(4); this is *not* a general formula
   # for converting periods of years to seconds: leap years need
   # careful handling; also this ignores leap seconds.
  SECONDS_1900_01_01_TO_1970_01_01 = 25567 * 24 * 60 * 60

  def initialize( host_v = nil )
    @host = host_v || TIME_SERVER
    @options = {
                 "Host" => @host,
                 "Telnetmode" => false,
                 "Timeout" => 30,
                 "Port" => "time"
               }
  end

   # Note that this does *not* deal with what happens if there is a timeout
   # or other failure to get the time from the time server.
  def time()
     # The time is the number of seconds since 00:00 (midnight) 1 January 1900
     # GMT, such that the time 1 is 12:00:01 am on 1 January 1900 GMT; this
     # base will serve until the year 2036.
    seconds = Net::Telnet.new(@options).recv(4).unpack('N').first
    Time.at( seconds - SECONDS_1900_01_01_TO_1970_01_01 )
  end
end

st = ServerTime.new
t = st.time
puts "Time from #{st.host} -> #{t}"
sleep 3
puts "Time from #{st.host} -> #{st.time}"