Files
punktfunk/crates/punktfunk-host
enricobuehler f23e0df64c fix(host): a compositor pin silently vetoed dedicated game sessions
`PUNKTFUNK_COMPOSITOR` is documented as "which backend to drive", but it also
quietly discarded `game_session=dedicated`: `resolve_compositor` gated the
dedicated route on `!overridden` and logged nothing either way. A host whose pin
was a forgotten validation leftover therefore went on displaying "dedicated" in
the console while every launch landed in the desktop instead — for 30 days on the
box that surfaced this, the only evidence being the ABSENCE of a log line.

The pin still wins, since it is the operator's explicit hand-set knob, but it now
says so and names itself.

Two further holes the same triage turned up:

- The pin put its backend into `available()` unconditionally AND skipped
  `apply_session_env`'s `XDG_CURRENT_DESKTOP` scrub, so `pick_compositor` could
  never return `None` — the one place `try_recover_session()` is called from. A
  pinned host whose gnome-shell had segfaulted therefore spent every connect on 8
  doomed `RemoteDesktop.CreateSession: ServiceUnknown` retries while the
  operator's configured `PUNKTFUNK_RECOVER_SESSION_CMD` sat unreachable behind
  that arm. Liveness is now read on both paths, and a pin aimed at a dead session
  takes the recovery exit with an error naming the pin. `needs_live_session()`
  exempts gamescope, which stands its own session up — pinning it on a headless
  box stays supported.

- A mode switch accepted before the pipeline existed was served the long way
  round: build at the now-stale mode, then immediately rebuild at the new one in
  the stream loop. That burns a display create, capture attach and encoder open
  on every such connect, and because the rebuild is deliberately
  create-before-drop it stands up two Mutter `RecordVirtual` monitors ~400 ms
  apart — which segfaults mutter 50.4 inside `meta_monitor_manager_rebuild` and
  takes down the whole desktop session, along with the game just launched into
  it (so the GAME looks like what crashed). Bring-up now adopts the newest queued
  mode and builds once, carrying over the H2/H3 correction ack that the replaced
  rebuild would have sent.

Verified on a real Linux host (192.168.1.21, x86_64): `cargo clippy --workspace
--all-targets --locked -- -D warnings`, `cargo fmt --all --check` and the
punktfunk-host + pf-vdisplay test suites all clean. The gate was proved
non-vacuous against a planted `compile_error!`.
2026-08-08 17:37:02 +02:00
..

punktfunk-host

The streaming host — the program you run on the machine whose desktop or games you want to stream. For each client that connects, it spins up a virtual display sized to that device, captures it on the GPU, encodes with hardware NVENC/VAAPI/AMF/QSV, and sends it out over a low-latency transport — no physical monitor, no letterboxing, no rearranging your real screens.

It speaks two protocols from one process:

  • GameStream — so any Moonlight / Artemis client works day one.
  • punktfunk/1 — punktfunk's own faster protocol (QUIC control plane, GF(2¹⁶) FEC + AES-GCM data plane) that the native clients use.

Runs on Linux (the primary, most battle-tested path) and Windows (x64). The shared protocol, FEC, and crypto live in punktfunk-core; this crate is everything platform-facing around it.

What it does

  • Per-client virtual displays at the exact WxH@Hz. Linux uses per-compositor backends — KWin, gamescope, Mutter, and Sway/wlroots; Windows uses its own all-Rust IddCx virtual display, even on the secure desktop (UAC / lock screen).
  • GPU zero-copy capture → encode. dmabuf → CUDA/Vulkan → NVENC on Linux; on Windows the host pushes frames straight into its own IDD (sealed IDD-push, no screen-scraping) → GPU encode. Encoders auto-select by GPU vendor: NVENC (NVIDIA), VAAPI (Linux AMD/Intel), AMF/QSV (Windows AMD/Intel), or software H.264 as a floor. HDR/10-bit and HEVC 4:4:4 supported.
  • Input injection. Mouse/keyboard (libei / gamescope EIS / wlr / Windows SendInput) and virtual gamepads — Xbox 360/One, DualSense, DualShock 4 — with rumble and HID feedback back-channels.
  • Audio both ways. Opus audio host→client, plus a virtual microphone the client can talk into.
  • Trust & discovery. A persistent host identity, SPAKE2 PIN pairing (default) or TOFU, and mDNS auto-advertisement so clients find the host without typing an IP.
  • Management API + web console. A REST API (mgmt.rs, OpenAPI at api/openapi.json) drives status, paired devices, and on-demand pairing; the browser UI is in web/.

Run it

punktfunk-host serve runs inside your desktop session. Bare serve is the secure native-only default (punktfunk/1 + the management API); add --gamestream on a trusted LAN to also accept stock Moonlight clients.

# Linux, from the repo root (see the repo README "Running on this box" for the headless recipe):
cargo run -rp punktfunk-host -- serve                 # native-only (secure default)
cargo run -rp punktfunk-host -- serve --gamestream    # + Moonlight compatibility

Then pair from the web console (https://<host-ip>:47992) or the client app.

Most people should install a package rather than run from source — see packaging/ (apt · rpm/COPR/bootc · Arch/sysext · Windows installer) and the per-platform guides at docs.punktfunk.unom.io/docs/install.

Subcommands

Command Purpose
serve The host (native punktfunk/1 + mgmt API; --gamestream adds Moonlight).
punktfunk1-host Standalone native-protocol listener for testing/measurement (--source virtual, --max-sessions).
openapi Print the management-API OpenAPI spec (regenerates api/openapi.json).
library Inspect the multi-store game library.
service · driver · web Windows: SCM service, driver install, bundled web console.
*-test / *-selftest / *-probe Diagnostics (input, zero-copy, HDR, compositor, gamepads).

--help lists them all.

Layout

src/
  main.rs            CLI + subcommand dispatch
  config.rs · session_plan.rs · session_tuning.rs · pipeline.rs   session setup + the frame pipeline
  vdisplay/          per-compositor virtual outputs (kwin · gamescope · mutter · wlroots)
  capture/ · capture.rs    screen/dmabuf capture (+ Windows IDD-push)
  encode/ · encode.rs      per-GPU encoders (nvenc · vaapi · ffmpeg_win (AMF/QSV) · sw)
  linux/zerocopy/    dmabuf → CUDA → NVENC bridges (EGL/GL tiled, Vulkan LINEAR)
  inject/ · inject.rs      input backends (libei · wlr · uinput gamepads · UHID DualSense/DS4)
  audio/ · audio.rs        Opus out + virtual mic (PipeWire / WASAPI)
  gamestream/        Moonlight compat: nvhttp · pairing · rtsp · control · stream · gamepad · apps
  native.rs      the native punktfunk/1 host (QUIC control + native-thread UDP data plane)
  mgmt.rs · native_pairing.rs · stats_recorder.rs   management API, pairing, perf capture
  hdr.rs · library.rs      HDR metadata; multi-store game library
  linux/ · windows/  platform-confined backends
  • punktfunk-core — the shared protocol · FEC · crypto core
  • Clients — the apps that connect (Apple · Linux · Windows · Android · probe)
  • Packaging & docs — install & operate
  • punktfunk-planning (internal planning repo) — architecture rationale and deep-dive plans