whoogle-search/app/utils/session.py
Ben Busby e06ff85579
Improve public instance session management (#480)
This introduces a new approach to handling user sessions, which should
allow for users to set more reliable config settings on public instances.

Previously, when a user with cookies disabled would update their config,
this would modify the app's default config file, which would in turn
cause new users to inherit these settings when visiting the app for the
first time and cause users to inherit these settings when their current
session cookie expired (which was after 30 days by default I believe).
There was also some half-baked logic for determining on the backend
whether or not a user had cookies disabled, which lead to some issues
with out of control session file creation by Flask.

Now, when a user visits the site, their initial request is forwarded to
a session/<session id> endpoint, and during that subsequent request
their current session id is matched against the one found in the url. If
the ids match, the user has cookies enabled. If not, their original
request is modified with a 'cookies_disabled' query param that tells
Flask not to bother trying to set up a new session for that user, and
instead just use the app's fallback Fernet key for encryption and the
default config.

Since attempting to create a session for a user with cookies disabled
creates a new session file, there is now also a clean-up routine included
in the new session decorator, which will remove all sessions that don't
include a valid key in the dict. NOTE!!! This means that current user
sessions on public instances will be cleared once this update is merged
in. In the long run that's a good thing though, since this will allow session
mgmt to be a lot more reliable overall for users regardless of their cookie
preference.

Individual user sessions still use a unique Fernet key for encrypting queries,
but users with cookies disabled will use the default app key for encryption
and decryption.

Sessions are also now (semi)permanent and have a lifetime of 1 year.
2021-11-17 19:35:30 -07:00

40 lines
1.0 KiB
Python

from cryptography.fernet import Fernet
from flask import current_app as app
REQUIRED_SESSION_VALUES = ['uuid', 'config', 'key']
def generate_user_key() -> bytes:
"""Generates a key for encrypting searches and element URLs
Args:
cookies_disabled: Flag for whether or not cookies are disabled by the
user. If so, the user can only use the default key
generated on app init for queries.
Returns:
str: A unique Fernet key
"""
# Generate/regenerate unique key per user
return Fernet.generate_key()
def valid_user_session(session: dict) -> bool:
"""Validates the current user session
Args:
session: The current Flask user session
Returns:
bool: True/False indicating that all required session values are
available
"""
# Generate secret key for user if unavailable
for value in REQUIRED_SESSION_VALUES:
if value not in session:
return False
return True