forked from unom/punktfunk
enricobuehler
5219107177
`packaging/windows/drivers/*` has run `deny(unsafe_op_in_unsafe_fn)` +
`deny(clippy::undocumented_unsafe_blocks)` for a while, with `forbid(unsafe_code)`
on the modules that need no unsafe at all. The main workspace had no lint config
whatsoever, so nothing stopped a clean crate from quietly growing an `unsafe`, and
nothing distinguished the handful of genuinely-unsafe lines inside a 600-line
`unsafe fn` from the safe ones surrounding them.
Three things, all mechanical:
* `#![forbid(unsafe_code)]` on the eight crates that already contain zero unsafe
(`pf-driver-proto`, `pf-host-config`, `pf-paths`, the three clean clients, both
tools). These were clean by accident, not by contract; now they are clean by
contract.
* `unsafe_op_in_unsafe_fn = "warn"` workspace-wide. `unsafe fn` states a contract
the CALLER must uphold — it was never meant to switch off checking for the whole
body. Measured fallout is 300 sites on Linux, and they are concentrated: six
files carry all of them, while `punktfunk-core`, `pf-frame`, `pf-clipboard` and
`pf-vdisplay` are already at zero. `warn` (not `deny`) so the build stays green
while those six are worked down; it flips to `deny` once they are. This is also
the Rust 2024 default, so it pays off the edition migration early.
* `proc::current_uid()` replaces eight `unsafe { libc::getuid() }` blocks. Each
site had copied out the same SAFETY note verbatim, which is the tell: `getuid()`
is parameterless, always succeeds and touches no memory, so there is no contract
for a caller to uphold and no reason for the unsafe to be visible eight times.
One `unsafe` behind a safe wrapper, none at the call sites.
Verified: `pf-vdisplay` builds clean on Linux (Nobara) at zero E0133; the
macOS-buildable crates build clean locally. No behaviour change.
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