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The Mac client now exercises the full cursor channel against capable hosts: desktop-mode sessions advertise CLIENT_CAP_CURSOR, the host stops compositing the pointer, and StreamView draws the forwarded shapes as the real NSCursor — plus the M3 host-driven model flip. - ABI v11: punktfunk_connect_ex9 (adds client_caps; ex7/ex8 pass 0 — Android untouched), PunktfunkCursorShape/State + the two next_cursor_* poll fns (audio-style borrow contract), and PUNKTFUNK_CLIENT_CAP_CURSOR. Fixed in passing: the first insertion split next_host_timing's cfg/no_mangle attributes off the fn, which silently dropped the symbol from the header AND dylib — caught by the Swift build, reattached with its docs. - PunktfunkConnection: clientCaps connect param, hostSupportsCursor, CursorShapeEvent/CursorStateEvent + nextCursorShape/nextCursorState (one cursor thread drains both planes; cursorLock joins the close() ladder). - SessionModel: desktop-mode sessions (DefaultsKey.mouseMode) connect with the cursor cap on macOS. - StreamView: shape cache (serial → NSCursor, straight-alpha RGBA via CGImage), resetCursorRects wears the HOST shape while the desktop model is engaged (hidden host pointer ⇒ invisible), latest-wins state pump, and the M3 auto-flip — edge-triggered on relative_hint, ⌃⌥⇧M sets an override latch cleared by the next host edge, leaving relative warps the pointer to the host position via the inverse letterbox mapping (CGWarpMouseCursorPosition, CursorCapture's coordinate convention). Verified: swift build + full test suites green (xcframework rebuilt at ABI v11, signed); core 218 tests + clippy -D warnings on Linux (.21). Co-Authored-By: Claude Fable 5 <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)
- punktfunk-planning:
implementation-plan.md(internal planning repo) — why GF(2¹⁶) FEC, the latency budget, and the architecture thesis