tornadocas.py

import re
import urllib
from tornado.web import RequestHandler

#CAS setting
CAS_SETTINGS = {
	#replace this with your cas server url
	'cas_server' : 'http://cas_server',
	#replace this with your website url
	'service_url' : 'http://service_url/deal_with_st',
	#CAS protocol version, 1.0 or 2.0? default is 2.0.
	'version' : 2
}

urlpattern = (
	( r'/login/?', tornadocas.LoginHandler ),
	( r'/deal_with_st/?', tornadocas.DealWithSTHandler ),
)


'''
Just redirect to cas server to got the server ticket.
'''
class LoginHandler( RequestHandler ):
	def get( self ):
		#redirect to cas server
		redirect_url = CAS_SETTINGS[ 'cas_server' ] + '/login?service=' + CAS_SETTINGS[ 'service_url' ]
		self.redirect( redirect_url )

'''
	Validate the SERVER TICKET, return None if failed, otherwise userid.
'''
class DealWithSTHandler( RequestHandler ):
	def get( self ):
		#what you finally get
		userid = None
		try:
			server_ticket = self.get_argument( 'ticket' )
		except Exception, e:
			print 'there is not server ticket in request argumets!'
			raise HTTPError( 404 )
		#validate the ST
		validate_suffix = '/validate' if CAS_SETTINGS[ 'version' ] == 1 else '/proxyValidate'
		validate_url = CAS_SETTINGS[ 'cas_server'] + validate_suffix + '?service=' + urllib.quote( CAS_SETTINGS[ 'service_url' ] ) + '&ticket=' + urllib.quote( server_ticket )
		response = urllib.urlopen( validate_url ).read()
		pattern = r'<cas:user>(.*)</cas:user>'
		match = re.search( pattern, response )
		if match:
			userid = match.groups()[ 0 ]
		if not userid:
			print 'validate failed!'
			raise HTTPError( 404 )

		self.deal_with_userid( userid )
	
	def deal_with_userid( self, userid ):
		pass