enricobuehler
b53710da1a
On-glass testing (Test 2, KWin .116) surfaced that a reconnect within the QUIC idle-timeout window (~8s) lands on a fresh SECOND display instead of reusing the kept one: the old session was still Active (not yet Lingering), so the registry's keep-alive reuse (which only matches Lingering) skipped it and the old session kept streaming to nobody. Three fixes: #3 Same-client reconnect preempt (the real fix): admission::preempt_same_identity() lists a reconnecting client's OWN still-live session(s) (same cert fingerprint); serve_session signals their stop + waits the release grace BEFORE acquiring, so the zombie tears down → its display lingers → the reconnect REUSES it instead of making a second. Implements the "preempts downstream" the admission docs already promised. Independent of the mode_conflict policy; the pure core (same_identity_stops) is unit-tested. #2 Deliberate quit skips linger: a client that deliberately disconnects closes the QUIC connection with QUIT_CLOSE_CODE (0x51, shared in core::quic); the host reads the ApplicationClosed reason and tears the display down immediately (registry release() gained force_immediate → Linger::Immediate; multi-session-safe via the pure lifecycle machine), while a bare disconnect still lingers for reconnect. Threaded via a session quit flag → the DisplayLease. NativeClient::disconnect_quit() + punktfunk-probe --quit drive it; GameStream (Quit App / h_cancel) is a documented follow-up. #1 Configurable disconnect-detection latency: the QUIC control-connection idle timeout (stream_transport, 8s default) is host-tunable via --idle-timeout-ms / PUNKTFUNK_IDLE_TIMEOUT_MS, clamped >=1s with a keep-alive that scales to it so a live session never false-closes. Default unchanged (8s stays load-bearing for the Windows IDD-push reconnect flow). Workspace check + 63 core / 215 host / 47 vdisplay tests green; clippy clean. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
punktfunk-core
The shared protocol core — the one place where punktfunk's transport, forward error correction, and crypto live. It's linked into the host and every native client, so there's exactly one implementation of the wire format everywhere.
Written in Rust with no async on the per-frame path (native threads only). It exposes both a normal Rust API and a stable, versioned C ABI, so the Swift and Kotlin clients — and any C embedder — link the same code as the Rust ones.
What's in here
- Transport & session (
session.rs,transport/,packet.rs) — thepunktfunk/1data plane over raw UDP: packetization, reassembly (with attacker-bounded limits), pacing, and socket tuning. - FEC (
fec/) — the wall-breaker. Two codes:- GF(2⁸) classic Reed–Solomon with the Cauchy generator matrix — byte-identical to the
nanorslibrary Moonlight uses, so our parity is decodable by a stock Moonlight client. - GF(2¹⁶) Leopard-RS (SIMD, O(n log n)) — up to 65535 shards/block, which removes the ~1 Gbps
FEC ceiling.
punktfunk/1negotiates this one.
- GF(2⁸) classic Reed–Solomon with the Cauchy generator matrix — byte-identical to the
- Crypto (
crypto.rs) — AES-128-GCM session encryption with per-direction nonce salts and sequence-as-AAD; SPAKE2 PIN pairing lives behind thequicfeature. - QUIC control plane (
quic.rs,client.rs, featurequic) — the Hello/Welcome/Start handshake, cert pinning/TOFU, reverse audio, and the embeddableNativeClientconnector. This is the only placetokio/quinnare allowed; the feature is off by default so the core stays runtime-free. - C ABI (
abi.rs) — the versioned surface (punktfunk_abi_version(),PunktfunkConfigcarrying its ownstruct_size) that generatesinclude/punktfunk_core.hvia cbindgen at build time.
Build outputs
The crate builds three ways at once (crate-type = ["lib", "cdylib", "staticlib"]):
| Output | Used by |
|---|---|
lib (rlib) |
the host, probe, and tools link it as a normal Rust crate |
cdylib (.so/.dylib) |
the Swift / Kotlin clients via the C ABI |
staticlib (.a) |
the C test harness and static embedding |
Test
cargo test -p punktfunk-core # unit + proptest + loopback
cargo run -p loss-harness # FEC loss-resilience sweep (no network needed)
bash crates/punktfunk-core/tests/c/run.sh # standalone C-ABI link + round-trip proof
Design invariants (do not regress)
- One core, linked everywhere — protocol/FEC/crypto live only here, behind the stable C ABI.
- No async on the hot path — the per-frame pipeline is native threads only;
quic(tokio/quinn) is control-plane only, feature-gated, off by default. - Security hardening stays intact — the reassembler bounds attacker-controlled fields before
allocating; AES-GCM keeps per-direction nonce salts + seq-as-AAD; the ABI checks
struct_size. Regression tests exist — keep them green.
Related
punktfunk-host— the streaming host built on this core- Clients — the apps that link this core over the C ABI (or directly, in Rust)
design/implementation-plan.md— why GF(2¹⁶) FEC, the latency budget, and the architecture thesis