def format_output_url(cls, url, **kw):
"""
Helper method used during redirect to ensure that the redirect
url (assisted by frame busting code or javasctipt) will point
to the correct domain and not have any extra dangling get
parameters. The extensions are also made to match and the
resulting url is utf8 encoded.
Node: for development purposes, also checks that the port
matches the request port
"""
u = UrlParser(url)
if u.is_sciteit_url():
# make sure to pass the port along if not 80
if not kw.has_key('port'):
kw['port'] = request.port
# disentagle the cname (for urls that would have
# cnameframe=1 in them)
u.mk_cname(**kw)
# make sure the extensions agree with the current page
if c.extension:
u.set_extension(c.extension)
# unparse and encode it un utf8
rv = _force_unicode(u.unparse()).encode('utf8')
if any(ch.isspace() for ch in rv):
raise ValueError("Space characters in redirect URL: [%r]" % rv)
return rv
