Intranet2 SSO

sso.py

"""
A wrapper for Intranet2's single sign-on system.

Here's a brief overview of how Iodine SSO works:
    - you make a request token (with generate_token)
    - you redirect the user to a URL containing that request token
    - when the user allows access, they are redirected back to your application
      with an access token in the "sso" parameter
    - you verify the access token (with check_access_token_validity)
    - if you need to, you can start a session to access the API and such
      (with start_intranet_session)

Based on Tim Cyrus' documentation and James Woglom's intranet work.
"""

import base64
import collections
import json
import requests
import time
import urllib

ROOT = "https://iodine.tjhsst.edu/"

def generate_token(service, callback, exp=120, method="get"):
    """
    Generate a single sign-on request URL. You can redirect the user to this in
    order to get an access token.

    Parameters:
    - service: a name for your application, shown to the user
    - callback: a callback URL, the user's browser will redirect here with a
                parameter containing an access token
    - exp: your request's expiration time in seconds (default 2 minutes)
    - method: callback request method, GET recommended

    Returns: a URL to redirect the user of your app to
    """
    data = {
        "title": service,
        "return": callback,
        "time": int(time.time()),
        "exp": int(time.time() + exp),
        "method": method.upper()
    }
    print(data)
    token = base64.b64encode(urllib.parse.urlencode(data).encode()).decode()
    return "{}sso?req={}".format(ROOT, token)

def check_access_token_validity(token):
    """
    Check the validity of a returned access token.

    Parameters:
    - token: the access token

    Returns: the validity of the access token, a boolean
    """
    return sso_info(token)["valid_key"]

def sso_info(token):
    """
    Get some information about an access token.

    Parameters:
    - token: the access token

    Returns: a dict with keys including but not limited to "username"
    """
    data = requests.get("{}/ajax/sso/valid_key".format(ROOT),
                        params=dict(sso=token)).text
    data = json.loads(data)
    return data["sso"]

def start_intranet_session(token):
    """
    Start a logged-in Intranet session using an access token.

    Parameters:
    - token: the access token

    Returns: a requests.Session object, or False if the access token is invalid
    """
    if not check_access_token_validity(token):
        return False

    session = requests.Session()
    session.get("https://iodine.tjhsst.edu/?&login_sso={}".format(token))
    return session