92 lines
6.2 KiB
Markdown
92 lines
6.2 KiB
Markdown
---
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id: steam-networking
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title: "Steam networking — the BT_STEAM wire (transport + lobby)"
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status: living
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source_sections: "docs/GLASS_COCKPIT.md §4; docs/STEAM_TEST.md; commits e79e8fa/48ede2f/f703bb1"
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related_topics: [glass-cockpit, multiplayer]
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key_terms: [PadRIO, miniconsole]
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open_questions: ["live 2-account cross-machine session (docs/STEAM_TEST.md) — the step-4 exit criterion"]
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---
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# Steam networking — the BT_STEAM wire
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Internet MP for the glass cockpit (dev tooling; gate `BT_STEAM`, requires `BT_GLASS`).
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**Status: CODE COMPLETE 2026-07-18; single-machine verified; live 2-machine test pending.**
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## The three layers
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1. **The wire seam** (`L4NET.CPP`, always compiled): file-local `BTNetSend/Recv/Accept/Close`
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wrappers around the 9 raw Winsock sites — pure code motion when OFF; under `BT_STEAM` each
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offers the op to the transport first. Est. delegates: `CheckSocket` (peer address),
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`OpenConnection` TCP_OPEN head, `GetMyAddress` (self token).
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2. **The transport** (`engine/MUNGA_L4/L4STEAMNET.*`, gated): `ISteamNetworkingSockets`
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pseudo-SOCKETs (`0x5EA0xxxx`); engine TCP byte stream over reliable-NoNagle messages with
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per-connection reassembly rings (recv: empty→`WSAEWOULDBLOCK`, closed→0); listen channels
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console=0 / game=1 (`CreateListenSocketP2P`); install on env `BT_STEAM_NET=1`; degrades to
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Winsock at every failure. Pump = `SteamAPI_RunCallbacks` AND sockets `RunCallbacks` (the
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general dispatch carries the async results — sockets-only pumping stalls).
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3. **The lobby** (`game/glass/btl4lobby.*`, gated): ISteamMatchmaking room (`btl4=1` list
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filter); pilots publish name/mech/color; the host's GO mints the roster and signals.
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## THE TOKEN MODEL (the FakeIP lesson) [T2]
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FakeIP does NOT survive the per-mission process relaunch (live-disproven prior-art assumption:
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menu and mission processes got different FakeIPs; the pod timed out dialing its own stale
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address). Roster addresses are therefore **opaque ipv4-shaped tokens** — `169.254.77.N`, port
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1501=console / 1502=game — minted by the HOST at GO and mapped to **Steam identities**;
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connections ride `ConnectP2P(identity, channel)`. Handoff to mission processes via env:
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`BT_FE_MYFAKE` (own token → `GetMyAddress` self-match) + `BT_FE_STEAMMAP`
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(`ip=steamid64;...`). The engine's roster matching, Waterloo swap logic, and self-identification
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all run UNCHANGED on tokens.
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## Testing
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Single-machine (verified): lobby-of-1 GO → token map → egg roster token → mission runs over the
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stock console ladder. Live 2-machine procedure + checklist: `docs/STEAM_TEST.md`. AppID 480
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(Spacewar) via auto-written gitignored `content/steam_appid.txt`.
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## FIRST REAL MULTI-PLAYER VERIFICATION — playtest night 4 (2026-07-27, 4.11.584) [T2 live]
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Players ran **three back-to-back Steam lobbies, host-and-join, 3+ players**, with no operator
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console involved — the first genuine field exercise of this path. **What worked:** hosting and
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joining (Draco, SAURON, somebodee, RajelAran all succeeded; "steam works for self-hosting? neat"),
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mission launch, **damage application** (previously suspected dead over Steam — "panels were
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changing color", "I was damaged"), **2 kills in one round**, clean round end, and the next mission
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launching after it. SAURON: "3 missions ran smooth ... felt smooth and normal". Load after LAUNCH
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felt "a bit long" (unquantified).
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**Found, and filed:** #68 (a failed JOIN/HOST exits the process silently — the FE returns on any
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`BTLobby_JoinAndWait` failure, so "Steam not running" and a real crash look identical to a player).
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Everything else the night surfaced was NOT Steam-specific and is tracked in the general issues:
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#67 (replicant torso twist / muzzle placement), #70 (twist after respawn), #55 (heat readout not
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reset on death), #69 (Sunder V1 → Denkou naming).
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**Lesson for triage:** a bug found in a Steam lobby is a Steam bug only if it lives in the lobby /
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token / transport layer. Everything above the seam is the same arcade mesh — the three replication
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symptoms this night produced would all reproduce on the relay.
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## THE EXIT CONTRACT (#163 -> #170, settled 2026-08-12) [T2 field-proven]
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Process-exit topology for every glass/steam process: **flush -> quiesce -> TerminateProcess.**
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`BTSteamNet_ShutdownAll` (L4STEAMNET.cpp) is a QUIESCE: gate `steamActive` FIRST (stops
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marshal/game-thread seam re-entry), `CloseConnection(..., linger=true)` on every connection
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("round over", not a peer-side timeout), close listeners, one `sockets->RunCallbacks()` drain,
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`Sleep(60)` grace. **It deliberately never calls `SteamAPI_Shutdown()`, and no exit path may
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return through the CRT** (menu-quit included -- it dies via `BTOrderlyDie`, btl4console.cpp).
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The two-failure history, because each fix's reason constrains the other:
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- **883 (no teardown at all):** bare `ExitProcess` ran DLL_PROCESS_DETACH with live SNS threads
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-> intermittent loader-lock deadlock -> "frozen view of how the game ended" + the menu child
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hung in `SteamAPI_Init` against the wedged half-dead sibling (#163, night15).
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- **913 (full `SteamAPI_Shutdown` before TerminateProcess):** at round end every peer closes
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simultaneously, so status events are ALWAYS in flight; Shutdown tears client state down while
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steamclient's own service thread dispatches them -> that thread calls literal NULL
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(0xc0000005 access=8 target=0x0, BaseThreadInitThunk root, ZERO btl4 frames) in the window
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before TerminateProcess (#170, night16: 7 hits / 3 machines / one module-relative stack).
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- **The stable point:** TerminateProcess kills all threads atomically with every pointer still
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valid (no detach, no dispatch window); the Steam client GCs the session on IPC pipe break --
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the standard crashed-game path (883 relaunched all night with no Shutdown ever called). The
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child-hang needed a WEDGED sibling, which TerminateProcess makes structurally impossible.
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Forensics rider: the crash filter (btl4main.cpp `BTCrashFilter`) now prints foreign frames as
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`<module.dll>+0xOFFSET` (VirtualQuery AllocationBase + GetModuleFileName), so a future
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foreign-thread crash names its DLL instead of an unresolvable ASLR address.
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## Key Relationships
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- Rides: [[glass-cockpit]] miniconsole (marshal has a Steam-wire branch) · Extends:
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[[multiplayer]] (the arcade mesh, unchanged above the seam)
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