pferd/PFERD/ilias/authenticators.py
Joscha 77a109bb7e Fix ilias shibboleth authenticator
The shibboleth site got a visual overhaul that slightly changed the classes of a
form we need.
2020-07-28 19:13:51 +00:00

132 lines
4.7 KiB
Python

"""
Authenticators that can obtain proper ILIAS session cookies.
"""
import abc
import logging
from typing import Optional
import bs4
import requests
from ..authenticators import TfaAuthenticator, UserPassAuthenticator
from ..utils import soupify
LOGGER = logging.getLogger(__name__)
class IliasAuthenticator(abc.ABC):
# pylint: disable=too-few-public-methods
"""
An authenticator that logs an existing requests session into an ILIAS
account.
"""
@abc.abstractmethod
def authenticate(self, sess: requests.Session) -> None:
"""
Log a requests session into this authenticator's ILIAS account.
"""
class KitShibbolethAuthenticator(IliasAuthenticator):
# pylint: disable=too-few-public-methods
"""
Authenticate via KIT's shibboleth system.
"""
def __init__(self, username: Optional[str] = None, password: Optional[str] = None) -> None:
self._auth = UserPassAuthenticator("KIT ILIAS Shibboleth", username, password)
self._tfa_auth = TfaAuthenticator("KIT ILIAS Shibboleth")
def authenticate(self, sess: requests.Session) -> None:
"""
Performs the ILIAS Shibboleth authentication dance and saves the login
cookies it receieves.
This function should only be called whenever it is detected that you're
not logged in. The cookies obtained should be good for a few minutes,
maybe even an hour or two.
"""
# Equivalent: Click on "Mit KIT-Account anmelden" button in
# https://ilias.studium.kit.edu/login.php
LOGGER.debug("Begin authentication process with ILIAS")
url = "https://ilias.studium.kit.edu/Shibboleth.sso/Login"
data = {
"sendLogin": "1",
"idp_selection": "https://idp.scc.kit.edu/idp/shibboleth",
"target": "/shib_login.php",
"home_organization_selection": "Mit KIT-Account anmelden",
}
soup = soupify(sess.post(url, data=data))
# Attempt to login using credentials, if necessary
while not self._login_successful(soup):
# Searching the form here so that this fails before asking for
# credentials rather than after asking.
form = soup.find("form", {"class": "full content", "method": "post"})
action = form["action"]
# Equivalent: Enter credentials in
# https://idp.scc.kit.edu/idp/profile/SAML2/Redirect/SSO
LOGGER.debug("Attempt to log in to Shibboleth using credentials")
url = "https://idp.scc.kit.edu" + action
data = {
"_eventId_proceed": "",
"j_username": self._auth.username,
"j_password": self._auth.password,
}
soup = soupify(sess.post(url, data=data))
if self._tfa_required(soup):
soup = self._authenticate_tfa(sess, soup)
if not self._login_successful(soup):
print("Incorrect credentials.")
self._auth.invalidate_credentials()
# Equivalent: Being redirected via JS automatically
# (or clicking "Continue" if you have JS disabled)
LOGGER.debug("Redirect back to ILIAS with login information")
relay_state = soup.find("input", {"name": "RelayState"})
saml_response = soup.find("input", {"name": "SAMLResponse"})
url = "https://ilias.studium.kit.edu/Shibboleth.sso/SAML2/POST"
data = { # using the info obtained in the while loop above
"RelayState": relay_state["value"],
"SAMLResponse": saml_response["value"],
}
sess.post(url, data=data)
def _authenticate_tfa(
self,
session: requests.Session,
soup: bs4.BeautifulSoup
) -> bs4.BeautifulSoup:
# Searching the form here so that this fails before asking for
# credentials rather than after asking.
form = soup.find("form", {"method": "post"})
action = form["action"]
# Equivalent: Enter token in
# https://idp.scc.kit.edu/idp/profile/SAML2/Redirect/SSO
LOGGER.debug("Attempt to log in to Shibboleth with TFA token")
url = "https://idp.scc.kit.edu" + action
data = {
"_eventId_proceed": "",
"j_tokenNumber": self._tfa_auth.get_token()
}
return soupify(session.post(url, data=data))
@staticmethod
def _login_successful(soup: bs4.BeautifulSoup) -> bool:
relay_state = soup.find("input", {"name": "RelayState"})
saml_response = soup.find("input", {"name": "SAMLResponse"})
return relay_state is not None and saml_response is not None
@staticmethod
def _tfa_required(soup: bs4.BeautifulSoup) -> bool:
return soup.find(id="j_tokenNumber") is not None