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https://github.com/dgtlmoon/changedetection.io.git
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Dennis Gaidaanddgtlmoon
b91082b38a
* Set Cache-Control: no-store on dynamic responses by default Pages with per-session content (settings, CSRF-token-bearing forms, watch data) had no Cache-Control header, so a misconfigured CDN or reverse proxy sitting in front of the app could cache and replay them across requests/sessions — most commonly surfacing as "CSRF tokens do not match" after the edge served a stale cached page. Routes that already set their own Cache-Control (static assets, screenshots, favicons) are left untouched. * Adding tests and moving function --------- Co-authored-by: dgtlmoon <dgtlmoon@gmail.com>
52 lines
2.3 KiB
Python
52 lines
2.3 KiB
Python
#!/usr/bin/env python3
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"""
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PR #4319: dynamic pages went out with no Cache-Control at all.
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Flask does send "Vary: Cookie" on any response that touched the session, so a
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spec-compliant shared cache would already key these per-session. An edge cache
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configured to key purely on URL ignores that, and one reporter's Cloudflare
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Worker did exactly that: it cached /settings, including the csrf_token embedded
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in the form, and every later save failed with "The CSRF tokens do not match" -
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or, worse, could hand one session's authenticated page to another visitor.
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An app-wide after_request fills in Cache-Control when the route didn't set one,
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so the explicit headers on assets/screenshots/favicons still win.
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"""
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def test_dynamic_pages_are_not_storable(client, live_server):
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# Any page carrying session state or a CSRF token - the cached copy is what
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# breaks form submits and leaks across sessions.
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for path in ['/', '/settings', '/login']:
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response = client.get(path)
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cache_control = response.headers.get('Cache-Control')
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assert cache_control is not None, (
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f"{path} sent no Cache-Control - a URL-keyed edge cache is free to store and "
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f"replay it, stale CSRF token and all"
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)
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assert 'no-store' in cache_control, (
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f"{path} must not be storable by an intermediary, got {cache_control!r}"
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)
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def test_routes_keep_their_own_cache_control(client, live_server):
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# The hook only fills in a missing header, so routes that deliberately
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# allow caching must come through untouched.
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# send_from_directory() always sets Cache-Control itself, so static files
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# never reach the hook at all.
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response = client.get('/static/styles/styles.css')
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assert response.status_code == 200
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assert 'no-store' not in response.headers.get('Cache-Control', ''), (
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f"static assets should keep werkzeug's own header, got "
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f"{response.headers.get('Cache-Control')!r}"
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)
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# And a route with an explicit long-lived, publicly cacheable header.
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response = client.get('/static/flags/4x3/ad.svg')
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assert response.status_code == 200
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assert response.headers.get('Cache-Control') == 'max-age=86400, public', (
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f"flag SVGs set their own 24h public cache header, got "
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f"{response.headers.get('Cache-Control')!r}"
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)
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