enricobuehler
23d0452157
The user direction after WP0: ENet exists only for Moonlight, so the native
plane must be provably safe and the compat planes a deliberate choice.
Opt-in, everywhere. Windows already was (unchecked installer task). The three
opt-out surfaces are flipped: the shipped systemd user unit (deb/RPM/Arch/
sysext) no longer bakes --gamestream into ExecStart — a new
PUNKTFUNK_GAMESTREAM=1 host.env knob (pf-host-config, OR-ed with the CLI
flag) is the packaged opt-in; the NixOS module default goes true→false, with
a module-check assertion that unset = native-only; the Deck installer takes
--gamestream to opt in (--no-gamestream kept as explicit-off). Docs
(quickstart, running-as-a-service, moonlight, ubuntu/fedora/arch firewall
sections, gnome/sway, how-it-works) rewritten to the opt-in shape; the
CHANGELOG carries the upgrade note.
Enforced-safe. punktfunk-core is #![deny(unsafe_code)] crate-wide — every
module that parses network bytes is safe Rust as a compile error, not a
census result. Carve-outs are exactly two documented classes, neither of
which interprets attacker bytes: the client surface (abi, client) and the
transport syscall-batching shims (udp/{apple,linux,windows}, qos_windows).
In punktfunk-host, the modules a secure-default host exposes — native
(cfg-not-test: its tests exercise the client C ABI on purpose),
native_pairing, mgmt, mgmt_token, discovery, wol — are #[forbid(unsafe_code)].
Gates: Linux amd64 container clippy --all-targets -D warnings clean over
core+host-config+host; core 204 tests green under the deny; mgmt 46/46,
control 6/6. .133 Windows clippy (shipped features, clean-first,
sentinel-checked) clean — covers the qos_windows/udp-windows carve-outs.
macOS + iOS cargo check green (the apple.rs carve-out compiles for real).
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