Telnetlib help. I need a case function.

[higgeldy Piggeldy]

Hi,
I wrote this script a while ago to renew my library books for me.
Our library here has a telnet interface where you can renew your
books.
So I tried to automate that for myself, now I need to upgrade it
because there are cases where it hangs on the read_until because the
server is sending something unexpected, and I am wondering if anyone
could help me get it to react to different input.
here is the script:

#!/usr/bin/python
import telnetlib
import sys
import string
import re
import regsub
import regex
import smtplib
succeed = re.compile("( *Successful renewal for title '.*'\.)")
maynot = re.compile("( *You may not renew '.*\.)")
noneleft = re.compile(" *No items were renewed .*")
due = re.compile ("( *Due Date = \d\d \w\w\w \d\d\d\d)")
tn = telnetlib.Telnet("dyna.multnomah.lib.or.us")
tn.read_until("login: ")
print "logging in!\n"
tn.write("fastcat\n")
tn.read_until(">>")
tn.write("\n")
#tn.read_until("<<VT100>> ")
tn.write("\n")
tn.read_until("N")
tn.write("\n")
tn.read_until("DYNA -")
tn.write("\n")
tn.read_until("<Enter> :")
def renew(thiscard,thispin,thisemail):
        fileout = open ('temp.txt','w')
        tn.write("17\n")
        tn.read_until("barcode")
        tn.write(thiscard+"\n")
        print "\n\nrenewing ",
        print "for ",thisemail
        tn.read_until("PHONE")
        tn.write(thispin+"\n")
        tn.read_until("below")
        tn.write("1\n")
        i=1
        for i in range(24):
                tmp = open('dyna.tmp','w')
                i=i+1
                tn.read_until("below")
                tn.write("r\n")
                (tn.read_until('renew'))
                tn.write(`i` + "\n")
                tmp.write (tn.read_until("Enter"))
                tn.write("\n")
                tmp.close()
                file = open('dyna.tmp','r')
                while 1:
                        line = file.readline()
                        if not line: break
                        successobj = succeed.search(line)
                        maynotobj = maynot.search(line)
                        dueobj = due.search(line)
                        if successobj:
                                fileout.write
(repr(successobj.groups())+"\n")
                        if maynotobj:
                                fileout.write
("ATTENTION"+"\n"+repr(maynotobj.groups())+"\nATTENTION\n")
                        if dueobj:
                                fileout.write
(repr(dueobj.groups())+"\n")
                file.close()
                # tn.read_until("below")
        tn.write("so\n")
        fileout.close()
        filein = open ("temp.txt","r")
        fileout = open ("temp2.txt","w")
        msg = "Subject:Automatic Library Renewal Notice
For:"+thisuser+".\r\n\r\nThank You for using my service.\nPlease feel
free to send any donations or suggestions to me at
sweetfamily at qwest.net\n\n"
        while 1:
                line = filein.readline()
                if not line: break
                matchobj = string.replace (line,"(","")
                matchobj = string.replace (matchobj,")","")
                matchobj = string.replace (matchobj,'"','')
                matchobj = string.replace (matchobj,"'","")
                matchobj = string.replace (matchobj,",","")
                matchobj = string.replace (matchobj,"/","")
                print matchobj,
                msg = msg+matchobj
                fileout.write(matchobj)
        filein.close()
        fileout.close()
        fromaddr = "From:andys at collegenet.com"
        toaddr = "To: "
        toaddr = toaddr + thisemail
        print toaddr
        sending = smtplib.SMTP('mail.collegenet.com')
        sending.set_debuglevel(0)
        sending.sendmail(fromaddr,toaddr,msg)
        sending.quit()
cardpatt = regex.compile ('^card:\(\w*\)')
pinpatt = regex.compile ('^pin:\(\w*\)')
emailpatt = regex.compile ("email:\(.*\)")
userpatt = regex.compile ("user:\(.*\)")
config = open("telnetter.cfg")
status =0
while 1:
        line = config.readline()
        if not line:break
        card = cardpatt.match(line)
        pin = pinpatt.match(line)
        email = emailpatt.match(line)
        user = userpatt.match(line)
        if card>=0:
                thiscard = str(cardpatt.group(1))
                status = status +1
        if pin>=0:
                thispin = str(pinpatt.group(1))
                status = status +1
        if email>=0:
                thisemail = str(emailpatt.group(1))
                status = status +1
        if user>=0:
                thisuser = str(userpatt.group(1))
                status = status+1
        if status == 4:
                status =0
                renew(thiscard,thispin,thisemail)
#renew("21168013143409","6422")
#renew("21168018228841","6422")
tn.read_until("Enter>")
tn.write("19\n")
tn.close()
print "DONE!!"


It trips up on the tn.read_until("below") because the server is
sending something else since there are no books to renew.

Thanks 
--Andrew