[InstaZDLL]

Summary

RFC-023 and its implementation in one pull request. It closes the three findings RFC-019 left open, closes what a disabled account had handed out, and bounds four client inputs that only the request body limited.

1. Every answer from another host is read under a ceiling. outbound::read_bounded_body(response, limit) is a reusable reader that refuses an announced giant unread and cuts off anything that outgrows the limit. It is used by Last.fm, Maloja and the portrait fetcher. The two Last.fm authorisation calls, which nothing bounded in time, now run under WAVEFLOW_SCROBBLE_REQUEST_TIMEOUT_SECS.
2. FFmpeg and ffprobe open local files and nothing else. Every input goes through media::file_input, which passes -protocol_whitelist file -i <path>: transcode, quality probe/measure/spectrogram, canvas probe and remux.
3. /reference is served from the binary. It embeds @scalar/api-reference 1.73.1, gzip-compressed and held to its published SHA-256 by a test, with the MIT licence alongside. It is served at a versioned path under a CSP of its own (scripts and connections from this origin only), and Scalar's fonts, telemetry, agent, MCP and toolbar are switched off. utoipa-scalar is dropped.
4. A disabled account shares and plays nothing. The share page, the share JSON and the share stream answer 404 like a missing share, and a refused opening counts no visit. Stream and canvas tickets stop at the next request instead of at their expiry. API tokens, sessions, refresh tokens and OAuth codes were already refused, but untested; each now has a test.
5. Other inputs of the same kind:
   • LRC timestamp expansion has an 8 MiB budget. Before, a 1 MiB upload could expand to tens of GB.
   • A playlist import stops at the first entry past 10,000.
   • The sync socket closes on a message over 4 KiB instead of buffering up to 64 MiB.
   • A search reads its first 256 characters and 16 terms.

Decisions

These are numbered as in docs/rfcs/RFC-023-hardening.md. In short:

• Oversized answers. If the body only refines a verdict (a Last.fm or Maloja scrobble), the status line decides, as it does for an unparseable body. Ambiguous was rejected because it turns into one decision a person must make per listen. If the body is the answer (the Last.fm session key or request token), the call fails as Unavailable. Failures are logged by verdict only, never with a URL or a body.
• The FFmpeg list is file. Measured on FFmpeg 8.0, a top-level http:// or concat: input used to be opened as asked; it is now refused. FFmpeg 8's own default already refused an HLS segment over http nested in a local file; the list makes that hold on builds with a wider default.
• /reference styles admit 'unsafe-inline'. This was measured: under a nonce, Chromium refused six of the <style> elements Scalar injects and the page rendered unstyled. Scripts stay 'self' only, with no eval.
• Reference DoS fix, raised by an automated security review before this PR was opened. Each request copied the 1.3 MB gzip bundle, and each request without gzip decompressed 4.4 MB again. Now the gzip body is Bytes::from_static over the embedded file, the decompressed body is made once per process in a OnceLock<Option<Bytes>> and shared by reference, and the page is shared the same way.
  • The uncompressed path is kept rather than always sending gzip. A body in an encoding the request did not admit is a wrong HTTP answer, and a script fetching the file would store compressed bytes under a .js name. The cost is 4.4 MB resident once such a client has asked, and nothing per request.
  • A test serves the bundle five times without Accept-Encoding and counts one decompression.
• The search bound narrows the query and never refuses it. It is the only observable change under /rest, recorded in docs/subsonic-compatibility.md.
• No migration.

Test plan

• cargo fmt --all --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-features (full suite, -j 2, own target dir)
• /reference checked in a browser against the built binary on port 4591:
  • the page renders;
  • every resource comes from 127.0.0.1:4591;
  • no CSP violation is reported;
  • the "try it" client reached /health on the same origin.
• New tests:
  • outbound: within the ceiling, endless body, unannounced oversized body, announced giant.
  • Last.fm: session and token answers over the ceiling, a scrobble answer over the ceiling. Maloja: an answer over the ceiling.
  • media::ffmpeg_opens_files_and_nothing_else and quality::the_analysis_opens_files_and_nothing_else. A loopback listener counts connections: a URL input, an HLS playlist naming the listener, and a concat: input, plus a real file as the control.
  • reference: pinned digest, gzip negotiation, document escaping, decompressed once. service::the_api_reference_is_served_from_the_binary.
  • Disabled account: auth::a_disabled_account_s_tokens_and_grants_all_stop_working, media::a_disabled_account_plays_nothing_it_handed_out, canvas::a_disabled_account_s_canvas_ticket_opens_nothing. Each re-enables the account at the end.
  • lyrics, playlist_file, catalog (search bound), and sync::the_sync_socket_closes_on_an_oversized_message.
• The test accounts are inserted as rows and reach HTTP through server-minted API tokens. Passwords, verifiers and keys are drawn at run time. No test uses a literal password.

Inversions

Each fix was reverted with the tests still in place, and the tests were run to confirm they fail for the right reason. The files were then restored from full-path backups, and git status came back clean.

Fix reverted	Test	Failure
Both checks in read_bounded_body	outbound announced/unannounced, Last.fm ×3, Maloja	Ok([...]) instead of TooLarge; the session key was read; the verdicts were AuthBroken / PermanentReject
-protocol_whitelist file	media, quality	concat: decoded; 2 connections to the listener
LRC budget	lyrics	the sheet was read as synced
Import ceiling in parse	playlist_file	None instead of Some(TooManyEntries)
Term and character bounds	catalog	39 ANDs instead of 15
Socket message and frame caps	sync	the socket answered the ping
Script src back to jsDelivr	service	assertion on our script tag
a.disabled in stream_track_for_user	media	the ticket played (200)
a.disabled in canvas_for_track	canvas	the canvas ticket opened (200)
a.disabled in the share_is_open macro	media	the share page answered 200
a.disabled in the API token, access and refresh lookups (one at a time)	auth	200 instead of 401 at each
account.disabled in issue_session_for_account	auth	the code granted before the account was disabled was cashed in
OnceLock around the decompression	reference	5 decompressions instead of 1

Not distinguishable by inversion, stated rather than claimed:

• The disabled check added to shared_track_owner. The share stream also goes through stream_track_for_user as its owner, so it stays closed with either one reverted.
• The HLS-over-http case in the FFmpeg test. FFmpeg 8 already refuses it by default; the URL and concat: cases are what tell the whitelist apart from its absence.
• The endless-body test in outbound. Reverting it would read until memory runs out; the finite oversized tests carry the inversion instead.

Deferred

These are listed in RFC-023 under What is still open:

• a demuxer whitelist for FFmpeg;
• a ceiling on the number of Subsonic parameters;
• lengths for free-text fields (playlist and bookmark comments, share descriptions, changed_by, library name at creation, track corrections, OAuth client_id/redirect_uri/state);
• a password ceiling;
• checking API token scopes;
• a request-body read timeout;
• sync_event retention;
• TOTP.

Notes for reviewers

• assets/scalar/api-reference-1.73.1.js.gz is a 1.3 MB binary: the npm package's dist/browser/standalone.js compressed with gzip -9n. .gitattributes now marks *.gz as binary.
• Expected merge overlap with the parallel PRs: docs/privacy.md (local edits), tests/support/mod.rs (two helpers appended at the end), and src/services/shares.rs (the share_is_open macro). No change was made to src/public_share.rs, src/config.rs or docs/operations.md.

Summary by CodeRabbit

• Nouvelles fonctionnalités
  • La référence API est intégrée à l’application et servie sans recours à un CDN.
• Améliorations
  • Les recherches sont limitées à 256 caractères et 16 termes ; les requêtes dépassant ces limites sont tronquées.
  • Des plafonds s’appliquent aux messages WebSocket, aux réponses externes, aux images, aux playlists importées et à l’expansion des paroles synchronisées. Les paroles trop volumineuses sont traitées comme du texte brut.
  • Les appels à Last.fm disposent d’un délai maximal.
• Sécurité
  • FFmpeg et ffprobe n’accèdent qu’aux fichiers locaux. Les ressources associées à un compte désactivé ne sont plus accessibles.
• Documentation
  • Les règles de confidentialité et les limites de recherche sont documentées.

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Walkthrough

La PR limite les réponses externes et plusieurs entrées. Elle restreint les protocoles des outils média à file, intègre Scalar au serveur et bloque certains accès associés aux comptes désactivés.

Changes: Limites et contrôles d’accès

Layer / File(s)	Summary
Réponses externes bornées src/outbound.rs, src/portrait.rs, src/podcast.rs, src/scrobblers/*, src/lib.rs, docs/privacy.md, docs/rfcs/RFC-023-hardening.md	Un lecteur partagé plafonne les corps reçus à 2 Mio. Les réponses de portrait, podcast, Last.fm et Maloja utilisent des limites. Last.fm applique aussi un délai aux appels d’autorisation.
Entrées média limitées au protocole file src/media.rs, src/quality/mod.rs, src/services/canvas.rs, docs/privacy.md, docs/rfcs/RFC-023-hardening.md	Les commandes FFmpeg et ffprobe fournissent leurs entrées via file_input, qui limite les protocoles à file. Les tests couvrent les fichiers locaux et le refus d’entrées HTTP et concat:.
Référence Scalar intégrée src/reference.rs, src/security_headers.rs, src/lib.rs, assets/scalar/*, Cargo.toml, .gitattributes, tests/service.rs, docs/privacy.md, docs/rfcs/RFC-023-hardening.md	Le serveur construit la page à partir du document OpenAPI et sert le bundle Scalar intégré. Le script est servi en gzip ou décompressé selon Accept-Encoding, avec des en-têtes de sécurité dédiés.
Accès des comptes désactivés src/catalog.rs, src/services/canvas.rs, src/services/shares.rs, tests/auth.rs, tests/canvas.rs, tests/media.rs, tests/support/mod.rs, docs/rfcs/RFC-023-hardening.md	Les requêtes de lecture de pistes, canvas et partages excluent les comptes désactivés. Les tests vérifient aussi le refus des jetons et sessions, puis le rétablissement des accès après réactivation.
Autres entrées bornées src/lyrics.rs, src/playlist_file.rs, src/services/playlists.rs, src/catalog.rs, src/api/sync.rs, tests/sync.rs, docs/subsonic-compatibility.md, docs/rfcs/RFC-023-hardening.md	La PR plafonne l’expansion LRC à 8 Mio, les entrées de playlist à 10 000, les recherches à 256 caractères et 16 termes, et les messages WebSocket à 4 Kio. Les recherches excédentaires sont tronquées plutôt que refusées.

Priority: Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Navigateur
  participant RouteurReference
  participant DocumentOpenAPI
  participant BundleScalar
  Navigateur->>RouteurReference: Demander /reference
  RouteurReference->>DocumentOpenAPI: Sérialiser le document OpenAPI
  RouteurReference-->>Navigateur: Renvoyer la page HTML
  Navigateur->>RouteurReference: Demander le script avec Accept-Encoding
  RouteurReference->>BundleScalar: Lire le bundle intégré ou décompressé
  RouteurReference-->>Navigateur: Renvoyer le script selon Accept-Encoding

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Merge Risk: Minimal · up to c5cde

This change clarifies and verifies existing Subsonic search behavior without introducing an actionable merge risk.

Security architecture risk: Low · up to c5cde

The inspected changes strengthen access checks and resource limits without revealing a newly introduced access bypass. Risk remains low rather than minimal because the changes span several security-sensitive paths and coverage is incomplete.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• observed — Public share authorization is scoped to the token hash, share identity, requested track, expiry, and active owner. Stream-track and canvas queries additionally retain user-to-library membership checks, so the new active-account condition supplements rather than replaces resource scoping.

Trust Boundaries and Controls

• observed — The routed test sends authenticated requests through the existing Subsonic route. Both search variants continue through the existing principal-scoped handler and catalogue service; inspection found no new endpoint or weakened visibility boundary associated with this signal.
• observed — The reference page permits scripts and connections only from its own origin, disables Scalar telemetry and agent/MCP options in configuration, and escapes opening angle brackets in embedded OpenAPI JSON. Inline styles and blob workers remain permitted; the policy is not a blanket prohibition on browser-side execution.

Resilience and Maintainability Implications

• observed — The active-owner predicate participates in the existing single-statement guarded visit increment. Disabled-owner refusal therefore does not consume a visit, and concurrent openings still test the cap at the write. Page eligibility and subsequent shared-track resolution remain read-only. Response assembly follows the committed increment, so the operation is not an end-to-end transaction; that ordering predates this PR.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 73.12% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 93 functions across 24 files. (1 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		Le titre résume clairement les principaux changements : durcissement, lectures bornées, protocoles FFmpeg, référence API intégrée et comptes désactivés. Il est précis et directement lié à la demande.
Description check		La description couvre le résumé, les changements, les décisions, le plan de test, les vérifications par inversion, les éléments différés et les notes pour les reviewers. Elle est complète et directeme…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

La description couvre le résumé, les changements, les décisions, le plan de test, les vérifications par inversion, les éléments différés et les notes pour les reviewers. Elle est complète et directement liée à la demande, même si elle n’utilise pas explicitement la section « Changes » du modèle.

Full details: Docstring Coverage

Explanation

Docstring coverage is 73.12% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 93 functions across 24 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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Review comments at @src/reference.rs:
- Around line 195-205: Modifiez le traitement de `Accept-Encoding` utilisé par
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• src/api/sync.rs
• src/catalog.rs
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• src/lyrics.rs
• src/media.rs
• src/outbound.rs
• src/playlist_file.rs
• src/portrait.rs
• src/quality/mod.rs
• src/reference.rs
• src/scrobblers/lastfm.rs
• src/scrobblers/maloja.rs
• src/security_headers.rs
• src/services/canvas.rs
• src/services/playlists.rs
• src/services/shares.rs
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• tests/canvas.rs
• tests/media.rs
• tests/service.rs
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- Line 265: Dans la documentation sur `search3` de Symfonium, remplacez « the
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