XBMC python handle images without content-length

import urlparse                 # http://docs.python.org/2/library/urlparse.html
import httplib                  # http://docs.python.org/2/library/httplib.html
import pickle                   # http://docs.python.org/2/library/pickle.html
import os                       # http://docs.python.org/2/library/os.html


url   = "http://forum.xbmc.org/uploads/avatars/avatar_e0dfbb69981bffe2a1eea03037a30b8d.gif?dateline=1331460338"
state = str(hash("asnormal")) # this could be a hash of sys.argv to avoid loading huge cache files from disk
img_ext = ('png', 'gif', 'jpg')
cache_dir = os.getcwd()
fpath = os.path.join( cache_dir, state )



def get_image_url(url):
    # RFC 3986 - Uniform Resource Identifier (URI): Generic Syntax
    # http://tools.ietf.org/html/rfc3986.html
    netloc = urlparse.urlparse( url ).netloc
    print "Create a HTTP connection to", netloc
    # HTTP1.1 request - http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html
    conn  = httplib.HTTPConnection( netloc, timeout=10 )
                            # nasty way of getting the selector
    conn.putrequest( "GET", url.lstrip("http://").lstrip(netloc) )
    conn.endheaders()
    result = conn.getresponse()

    # Manage the result based on http status. Redirects could also be cached
    if result.status != 200: raise httplib.InvalidURL( "status %i" % result.status )

    # Check for the content-length header field, could also check that content-type
    # field indicates a image
    if "content-lengthd"  in (name.lower() for name, value in result.getheaders()):
        print "Content-Length header field found"
        conn.close()
        return url

    # Need to write the image to disk before handing the image location to XBMC
    new_url = os.path.join( cache_dir, str(hash(url)) )
    print "write image data to", new_url
    fh = open( new_url, "wb" )
    fh.write( result.read() )
    fh.close()
    conn.close()

    return new_url



if not os.path.isfile( fpath ):
    cache = dict()
else:
    fhndl = open( fpath, 'rb' )
    cache = pickle.load( fhndl )
    fhndl.close()

print url

if not hash(url) in cache:
    # is cached version expired?
    # if ( time() - (cache_time * 3600) >= expiration_time )
    print "Not found in cache"
    if ( True not in ( url[-len(x):] == x for x in img_ext ) ):
        print "None of extensions in tuple at the end of the url"
        try:
            url = get_image_url(url)
        except httplib.InvalidURL as e:
            print e
        else:
            cache[hash(url)] = url

print url

fhndl = open(fpath, 'wb')
pickle.dump(cache, fhndl)
fhndl.close()