self.__logout_response is not bytes that make lxml error

[linnil1]

Hi,
I run the code just almost same as demo-flask.
And when it run to this line
redirect(auth.logout(name_id=name_id, session_index=session_index)).
This is error output:

[2018-05-04 22:26:48,887] ERROR in app: Exception on / [GET]
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/app/LoginWeb/tzfserver/start.py", line 88, in Login
    url = auth.process_slo(delete_session_cb=dscb)
  File "/usr/local/lib/python3.6/site-packages/onelogin/saml2/auth.py", line 144, in process_slo
    logout_response = OneLogin_Saml2_Logout_Response(self.__settings, get_data['SAMLResponse'])
  File "/usr/local/lib/python3.6/site-packages/onelogin/saml2/logout_response.py", line 42, in __init__
    self.document = OneLogin_Saml2_XML.to_etree(self.__logout_response)
  File "/usr/local/lib/python3.6/site-packages/onelogin/saml2/xml_utils.py", line 65, in to_etree
    return OneLogin_Saml2_XML._parse_etree(xml)
  File "/usr/local/lib/python3.6/site-packages/defusedxml/lxml.py", line 143, in fromstring
    rootelement = _etree.fromstring(text, parser, base_url=base_url)
  File "src/lxml/etree.pyx", line 3213, in lxml.etree.fromstring
  File "src/lxml/parser.pxi", line 1871, in lxml.etree._parseMemoryDocument
ValueError: Unicode strings with encoding declaration are not supported. Please use bytes input or XML fragments without declaration.

with

• python 3.6.4
• Flask (1.0.2)
• gunicorn (19.8.1)
• lxml (4.2.1)
• python3-saml (1.4.1)
• xmlsec (1.3.3)

I solve it by modifying logout_response.py
to this self.document = OneLogin_Saml2_XML.to_etree(self.__logout_response.encode())

Do I have wrong configuration that makes this error?

[pitbulk]

what value had the nameid?

[linnil1]

Just same as demo code
After login,
auth.get_nameid() is store in session.
session['samlNameId'] = auth.get_nameid()
And before logout,
name_id is restore from session['samlNameId']

name_id = session['samlNameId']
return redirect(auth.logout(name_id=name_id, session_index=session_index))

[omardlhz]

@linnil1 Was this issue ever resolved?