Rewrite session behavior for public instances

This introduces a new approach to handling user sessions.

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. There was also some janky logic for determining on the
backend whether or not a user had cookies disabled, which lead to some
issues with out of control session 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.

Sessions are also now (semi)permanent and have a lifetime of 1 year.

app/__init__.py

@@ -21,9 +21,9 @@ if os.getenv("WHOOGLE_DOTENV", ''):
                              dotenv_path))
 
 app.default_key = generate_user_key()
-app.no_cookie_ips = []
 app.config['SECRET_KEY'] = os.urandom(32)
 app.config['SESSION_TYPE'] = 'filesystem'
+app.config['SESSION_COOKIE_SAMESITE'] = 'strict'
 app.config['VERSION_NUMBER'] = '0.6.0'
 app.config['APP_ROOT'] = os.getenv(
     'APP_ROOT',

app/models/config.py

@@ -18,7 +18,7 @@ class Config:
         self.block_title = os.getenv('WHOOGLE_CONFIG_BLOCK_TITLE', '')
         self.block_url = os.getenv('WHOOGLE_CONFIG_BLOCK_URL', '')
         self.ctry = os.getenv('WHOOGLE_CONFIG_COUNTRY', '')
-        self.theme = os.getenv('WHOOGLE_CONFIG_THEME', '')
+        self.theme = os.getenv('WHOOGLE_CONFIG_THEME', 'system')
         self.safe = read_config_bool('WHOOGLE_CONFIG_SAFE')
         self.dark = read_config_bool('WHOOGLE_CONFIG_DARK')  # deprecated
         self.alts = read_config_bool('WHOOGLE_CONFIG_ALTS')

app/routes.py

@@ -5,6 +5,7 @@ import json
 import pickle
 import urllib.parse as urlparse
 import uuid
+from datetime import timedelta
 from functools import wraps
 
 import waitress
@@ -20,6 +21,7 @@ from bs4 import BeautifulSoup as bsoup
 from flask import jsonify, make_response, request, redirect, render_template, \
     send_file, session, url_for
 from requests import exceptions
+from requests.models import PreparedRequest
 
 # Load DDG bang json files only on init
 bang_json = json.load(open(app.config['BANG_FILE']))
@@ -45,23 +47,67 @@ def auth_required(f):
     return decorated
 
 
+def session_required(f):
+    @wraps(f)
+    def decorated(*args, **kwargs):
+        if (valid_user_session(session) and
+                'cookies_disabled' not in request.args):
+            g.session_key = session['key']
+        else:
+            invalid_sessions = []
+            session.pop('_permanent', None)
+            for user_session in os.listdir(app.config['SESSION_FILE_DIR']):
+                session_path = os.path.join(
+                        app.config['SESSION_FILE_DIR'],
+                        user_session)
+                with open(session_path, 'rb') as session_file:
+                    _ = pickle.load(session_file)
+                    data = pickle.load(session_file)
+                    if type(data) == 'dict' and 'valid' in data:
+                        continue
+                    invalid_sessions.append(session_path)
+
+            for invalid_session in invalid_sessions:
+                os.remove(invalid_session)
+            g.session_key = app.default_key
+
+        return f(*args, **kwargs)
+
+    return decorated
+
+
 @app.before_request
 def before_request_func():
     g.request_params = (
         request.args if request.method == 'GET' else request.form
     )
-    g.cookies_disabled = False
+
+    # Skip pre-request actions if verifying session
+    if '/session' in request.path and not valid_user_session(session):
+        return
+
+    default_config = json.load(open(app.config['DEFAULT_CONFIG'])) \
+        if os.path.exists(app.config['DEFAULT_CONFIG']) else {}
 
     # Generate session values for user if unavailable
-    if not valid_user_session(session):
+    if (not valid_user_session(session) and
-        session['config'] = json.load(open(app.config['DEFAULT_CONFIG'])) \
+            'cookies_disabled' not in request.args):
-            if os.path.exists(app.config['DEFAULT_CONFIG']) else {}
+        session['config'] = default_config
         session['uuid'] = str(uuid.uuid4())
-        session['key'] = generate_user_key(True)
+        session['key'] = generate_user_key()
-
+        return redirect(url_for(
-        # Flag cookies as possibly disabled in order to prevent against
+            'session_check',
-        # unnecessary session directory expansion
+            session_id=session['uuid'],
-        g.cookies_disabled = True
+            follow=request.url), code=307)
+    elif 'cookies_disabled' not in request.args:
+        # Set session as permanent
+        session.permanent = True
+        app.permanent_session_lifetime = timedelta(days=365)
+        g.user_config = Config(**session['config'])
+    else:
+        # User has cookies disabled, fall back to immutable default config
+        session.pop('_permanent', None)
+        g.user_config = Config(**default_config)
 
     # Handle https upgrade
     if needs_https(request.url):
@@ -69,8 +115,6 @@ def before_request_func():
             request.url.replace('http://', 'https://', 1),
             code=308)
 
-    g.user_config = Config(**session['config'])
-
     if not g.user_config.url:
         g.user_config.url = request.url_root.replace(
             'http://',
@@ -86,19 +130,6 @@ def before_request_func():
 
 @app.after_request
 def after_request_func(resp):
-    # Check if address consistently has cookies blocked,
-    # in which case start removing session files after creation.
-    #
-    # Note: This is primarily done to prevent overpopulation of session
-    # directories, since browsers that block cookies will still trigger
-    # Flask's session creation routine with every request.
-    if g.cookies_disabled and request.remote_addr not in app.no_cookie_ips:
-        app.no_cookie_ips.append(request.remote_addr)
-    elif g.cookies_disabled and request.remote_addr in app.no_cookie_ips:
-        session_list = list(session.keys())
-        for key in session_list:
-            session.pop(key)
-
     resp.headers['Content-Security-Policy'] = app.config['CSP']
     if os.environ.get('HTTPS_ONLY', False):
         resp.headers['Content-Security-Policy'] += 'upgrade-insecure-requests'
@@ -122,12 +153,22 @@ def home():
     return redirect(url_for('.index'))
 
 
+@app.route('/session/<session_id>', methods=['GET', 'PUT', 'POST'])
+def session_check(session_id):
+    if 'uuid' in session and session['uuid'] == session_id:
+        session['valid'] = True
+        return redirect(request.args.get('follow'))
+    else:
+        follow_url = request.args.get('follow')
+        req = PreparedRequest()
+        req.prepare_url(follow_url, {'cookies_disabled': 1})
+        session.pop('_permanent', None)
+        return redirect(req.url, code=307)
+
+
 @app.route('/', methods=['GET'])
 @auth_required
 def index():
-    # Reset keys
-    session['key'] = generate_user_key(g.cookies_disabled)
-
     # Redirect if an error was raised
     if 'error_message' in session and session['error_message']:
         error_message = session['error_message']
@@ -144,7 +185,10 @@ def index():
                            logo=render_template(
                                'logo.html',
                                dark=g.user_config.dark),
-                           config_disabled=app.config['CONFIG_DISABLE'],
+                           config_disabled=(
+                               app.config['CONFIG_DISABLE'] or
+                               not valid_user_session(session) or
+                               'cookies_disabled' in request.args),
                            config=g.user_config,
                            tor_available=int(os.environ.get('TOR_AVAILABLE')),
                            version_number=app.config['VERSION_NUMBER'])
@@ -179,6 +223,7 @@ def search_html():
 
 
 @app.route('/autocomplete', methods=['GET', 'POST'])
+@session_required
 def autocomplete():
     ac_var = 'WHOOGLE_AUTOCOMPLETE'
     if os.getenv(ac_var) and not read_config_bool(ac_var):
@@ -212,13 +257,13 @@ def autocomplete():
 
 
 @app.route('/search', methods=['GET', 'POST'])
+@session_required
 @auth_required
 def search():
     # Update user config if specified in search args
     g.user_config = g.user_config.from_params(g.request_params)
 
-    search_util = Search(request, g.user_config, session,
+    search_util = Search(request, g.user_config, g.session_key)
-                         cookies_disabled=g.cookies_disabled)
     query = search_util.new_search_query()
 
     bang = resolve_bang(query=query, bangs_dict=bang_json)
@@ -286,9 +331,12 @@ def search():
 
 
 @app.route('/config', methods=['GET', 'POST', 'PUT'])
+@session_required
 @auth_required
 def config():
-    config_disabled = app.config['CONFIG_DISABLE']
+    config_disabled = (
+            app.config['CONFIG_DISABLE'] or
+            not valid_user_session(session))
     if request.method == 'GET':
         return json.dumps(g.user_config.__dict__)
     elif request.method == 'PUT' and not config_disabled:
@@ -315,11 +363,6 @@ def config():
                     app.config['CONFIG_PATH'],
                     request.args.get('name')), 'wb'))
 
-        # Overwrite default config if user has cookies disabled
-        if g.cookies_disabled:
-            open(app.config['DEFAULT_CONFIG'], 'w').write(
-                json.dumps(config_data, indent=4))
-
         session['config'] = config_data
         return redirect(config_data['url'])
     else:
@@ -327,6 +370,7 @@ def config():
 
 
 @app.route('/url', methods=['GET'])
+@session_required
 @auth_required
 def url():
     if 'url' in request.args:
@@ -342,15 +386,17 @@ def url():
 
 
 @app.route('/imgres')
+@session_required
 @auth_required
 def imgres():
     return redirect(request.args.get('imgurl'))
 
 
 @app.route('/element')
+@session_required
 @auth_required
 def element():
-    cipher_suite = Fernet(session['key'])
+    cipher_suite = Fernet(g.session_key)
     src_url = cipher_suite.decrypt(request.args.get('url').encode()).decode()
     src_type = request.args.get('type')
 

app/utils/search.py

@@ -52,16 +52,15 @@ class Search:
     Attributes:
         request: the incoming flask request
         config: the current user config settings
-        session: the flask user session
+        session_key: the flask user fernet key
     """
-
+    def __init__(self, request, config, session_key, cookies_disabled=False):
-    def __init__(self, request, config, session, cookies_disabled=False):
         method = request.method
         self.request_params = request.args if method == 'GET' else request.form
         self.user_agent = request.headers.get('User-Agent')
         self.feeling_lucky = False
         self.config = config
-        self.session = session
+        self.session_key = session_key
         self.query = ''
         self.cookies_disabled = cookies_disabled
         self.search_type = self.request_params.get(
@@ -96,7 +95,7 @@ class Search:
         else:
             # Attempt to decrypt if this is an internal link
             try:
-                q = Fernet(self.session['key']).decrypt(q.encode()).decode()
+                q = Fernet(self.session_key).decrypt(q.encode()).decode()
             except InvalidToken:
                 pass
 
@@ -115,7 +114,7 @@ class Search:
         """
         mobile = 'Android' in self.user_agent or 'iPhone' in self.user_agent
 
-        content_filter = Filter(self.session['key'],
+        content_filter = Filter(self.session_key,
                                 mobile=mobile,
                                 config=self.config)
         full_query = gen_query(self.query,

app/utils/session.py

@@ -4,7 +4,7 @@ from flask import current_app as app
 REQUIRED_SESSION_VALUES = ['uuid', 'config', 'key']
 
 
-def generate_user_key(cookies_disabled=False) -> bytes:
+def generate_user_key() -> bytes:
     """Generates a key for encrypting searches and element URLs
 
     Args:
@@ -16,9 +16,6 @@ def generate_user_key(cookies_disabled=False) -> bytes:
         str: A unique Fernet key
 
     """
-    if cookies_disabled:
-        return app.default_key
-
     # Generate/regenerate unique key per user
     return Fernet.generate_key()
 

requirements.txt

@@ -7,7 +7,7 @@ chardet==3.0.4
 click==8.0.3
 cryptography==3.3.2
 Flask==1.1.1
-Flask-Session==0.3.2
+Flask-Session==0.4.0
 idna==2.9
 itsdangerous==1.1.0
 Jinja2==2.11.3