enricobuehler
449a67ce8d
The unified-stats equation's host+network stage was one opaque number because the wire carried nothing but pts_ns. Now the host reports its own share per frame: when the client's Hello sets VIDEO_CAP_HOST_TIMING (0x08), the send thread emits a 13-byte 0xCF datagram — [tag][pts_ns u64][host_us u32] — right after the AU's last packet leaves the socket, so host_us = capture→fully-sent (capture read/convert, encode, FEC+seal, paced send) against the same anchor the wire pts carries. Clients correlate by pts_ns and derive network = (received + clock_offset − pts) − host_us; the two terms tile per frame by construction. Back-compat is free in all four combinations: old clients ignore unknown datagram tags, old hosts ignore unknown cap bits (client keeps the combined stage). The hardened data-plane format is untouched — this rides the established QUIC side-plane pattern (0xC8…0xCE). NativeClient ORs the bit in unconditionally and exposes next_host_timing(); the C ABI gains PunktfunkHostTiming + punktfunk_connection_next_host_timing (additive). The synthetic host emits 0xCF too, so pure-loopback protocol tests cover the plane. The probe reports the split (host_p50/p95_us · net_p50/p95_us) and is our direct analogue of Sunshine's "host processing latency" — ours additionally includes the paced send. Validated on loopback (synthetic host + probe, debug build): 240/240 AUs matched, host_p50 6.5 ms + net_p50 6.4 ms ≈ capture→received p50 13.0 ms. Core suite + new 0xCF roundtrip/truncation test green; host+core+probe clippy clean. 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)
design/implementation-plan.md— why GF(2¹⁶) FEC, the latency budget, and the architecture thesis