"""

rfc868

Network Working Group					     J. Postel - ISI
Request for Comments: 868				K. Harrenstien - SRI
								    May 1983


Time Protocol


This RFC specifies a standard for the ARPA Internet community. Hosts on the
ARPA Internet that choose to implement a Time Protocol are expected to adopt
and implement this standard.

This protocol provides a site-independent, machine readable date and time.
The Time service sends back to the originating source the time in seconds
since midnight on January first 1900.

One motivation arises from the fact that not all systems have a date/time
clock, and all are subject to occasional human or machine error. The use
of time-servers makes it possible to quickly confirm or correct a system's
idea of the time, by making a brief poll of several independent sites on
the network.

This protocol may be used either above the Transmission Control Protocol (TCP)
or above the User Datagram Protocol (UDP).

When used via TCP the time service works as follows:

	S: Listen on port 37 (45 octal).
	U: Connect to port 37.
	S: Send the time as a 32 bit binary number.
	U: Receive the time.
	U: Close the connection.
	S: Close the connection.

The server listens for a connection on port 37. When the connection is
established, the server returns a 32-bit time value and closes the
connection. If the server is unable to determine the time at its site,
it should either refuse the connection or close it without sending anything.

When used via UDP the time service works as follows:

	S: Listen on port 37 (45 octal).
	U: Send an empty datagram to port 37.
	S: Receive the empty datagram.
	S: Send a datagram containing the time as a 32 bit binary number.
	U: Receive the time datagram.

The server listens for a datagram on port 37.  When a datagram arrives,
the server returns a datagram containing the 32-bit time value.  If the server
is unable to determine the time at its site, it should discard the arriving
datagram and make no reply.

The Time

The time is the number of seconds since 00:00 (midnight) 1 January 1900 UTC,
such that the time 1 is 12:00:01 am on 1 January 1900 GMT; this base will
serve until the year 2036.

For example:

the time

	2,208,988,800 corresponds to 00:00  1 Jan 1970 GMT,

	2,398,291,200 corresponds to 00:00  1 Jan 1976 GMT,

	2,524,521,600 corresponds to 00:00  1 Jan 1980 GMT,

	2,629,584,000 corresponds to 00:00  1 May 1983 GMT,

	-1,297,728,000 corresponds to 00:00 17 Nov 1858 GMT.

"""

import time

from SocketServer import *

TIME_PORT = 37


def bin2asc(bin, len = 4):
	s = ''
	for i in range(len):
		bin, c = divmod(bin, 256)
		s = chr(c) + s		# network byte order!
	return s


class TimeHandler:
	def getTime(self):
		t = long(time.time()) + 2208988800L	# seconds from 1900-01-01 to 1970-01-01
		if t > 0xFFFFFFFFL:			# too long to fit in 4 bytes
			return ''
		return bin2asc(t)

	def handle(self):
		self.wfile.write(self.getTime())
		print self.client_address, 'Done'

class TCPTimeHandler(TimeHandler, StreamRequestHandler):
	pass

class UDPTimeHandler(TimeHandler, DatagramRequestHandler):
	pass


################################################################

def server():
	server_address = ('', TIME_PORT)

	timed_tcp = TCPServer(server_address, TCPTimeHandler)
	timed_udp = UDPServer(server_address, UDPTimeHandler)

	print "Serving TIME on port", TIME_PORT, "..."
	try:
		timed_tcp.serve_forever()
		timed_udp.serve_forever()
	except:
		timed_tcp.socket.close()
		del timed_tcp

def test():
	print bin2asc(0x41526374)

if 1 or __name__ == '__main__':
	server()