Authenticate with ASP using Python

aspx.py

import BeautifulSoup
import cookielib
import urllib
import urllib2

username,password = 'SomeUser','$ecret'
controller = 'http://example.com/SomeLameLoginPage.aspx'

post = {
  '__EVENTVALIDATION' : None, # These "__" will be present for every *.aspx page
  '__VIEWSTATE' : None,
  'btnLogin': 'Login', # These fields are application dependent
  'tbLogin' : username,
  'tbPassword' : password
}
      
cookiejar = cookielib.CookieJar()
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cookiejar))
urllib2.install_opener(opener)
    
# Snag ASP fields so we can properly POST our login information and get
# out authentication cookie
    
f = opener.open(controller)
soup = BeautifulSoup.BeautifulSoup(f)
for i in [k for k,v in post.iteritems() if v is None]
  post[i] = soup.find('input', {'id':i})['value']
opener.open(controller, urllib.urlencode(post))

# Now that we're logged in and have our cookie, we can get some content

f = opener.open(contentController)