MatchSim._recv_input now validates before decoding (§3.1 steps 2-3):
per-peer rolling-1s rate limiting (packet count AND byte budget, dropping
over-budget packets and disconnecting after 3 consecutive over-budget
seconds), and framing validation (redundancy count and payload size
checked against NetCodec's own layout before unpack_input ever runs,
disconnecting after 20 malformed packets). Framing has to be validated
explicitly rather than relying on decode failure: StreamPeerBuffer
silently zero-fills past EOF instead of erroring, a finding from Phase
2's adversarial review.
networked_match.gd's _on_input_received now rejects any seq claiming to
be more than 20 ticks ahead of the current server tick (§3.1 step 4) and
counts (rather than silently ignoring) input from a peer with no slot,
for observability.
Verified with two new permanent regression tests (networked_match_smoke.gd
--role=client-abuse-malformed / client-abuse-flood) that call
MatchSim._recv_input directly with garbage bytes and a legitimate-but-
too-frequent flood, respectively, bypassing the honest client encoder
entirely - the same thing a hostile custom client sending raw ENet
packets would look like. Both confirm real disconnection, not just that
the server tolerates the abuse.
Two bugs surfaced by getting these tests to actually pass cleanly: a
GDScript lambda-capture-by-value mistake in the tests themselves (a
plain `var disconnected := false` mutated inside a signal-handler lambda
never became visible to the enclosing function - fixed by capturing a
single-element Array instead, which is captured by reference); and a
narrow real race where NetworkManager's own ping/pong reply could target
a peer that a concurrent abuse-triggered disconnect had just removed
from the same poll() batch, now guarded. (Passing disconnect_peer's
`force` parameter as an attempted fix for a related one-off benign error
was tried and reverted - it made Godot's own peer-list bookkeeping
inconsistent, producing hundreds of errors instead of one; verified
empirically rather than assumed.)
Full regression suite, including the net-sim-latency milestone gate,
re-run clean.
New NetSim autoload: seeded, CLI-driven (--net-sim-latency/-jitter/-loss/-dup)
latency/jitter/loss/duplicate decorator, a true no-op passthrough unless a
flag is set. Wraps MatchSim.send_input/send_snapshot per the design doc's
scope, plus NetworkManager's ping/pong so the already-tested RTT/clock
measurement becomes the acceptance signal for "raises observed RTT" without
waiting on Phase 3's per-peer snapshot echo.
Two real bugs found while building and verifying this against Phase 2's own
milestone gate (a real match under --net-sim-latency 80 --net-sim-jitter
20, not just LAN): a timestamp captured inside a delayed RPC closure
silently ate that side's own added delay out of the round-trip
measurement instead of adding to it; and a delayed send whose target
disconnected (or whose own process had already shut down) during the hold
threw RPC errors, since the existing get_peers() filtering only checked
validity at schedule time. Fixed by capturing timestamps before handing
off to NetSim, and by having NetSim re-validate the target at fire time.
Phase 2's milestone gate now passes for real: a full 1v1 under simulated
80ms latency / 20ms jitter still shows clean server-authoritative
movement and zero RPC errors. Full Phase 1 + Phase 2 regression suite
re-verified clean with NetSim present but inactive.
Lands tasks 1.0-1.8 of multiplayer-todo.md: the pure-function test runner,
net_codec (wire format quantizers/pack-unpack), NetworkManager (ENet
transport, manual polling, min-RTT clock sync), MatchNet (handshake,
protocol/tick-rate gating, roster with team+ready state), lobby.tscn (team
columns, switch team, ready toggle), server_boot.tscn (headless dedicated
server with structured logging and an overrun watchdog), and main_menu.gd's
Host/Join-by-IP UI (connecting overlay, cancel, bounded failure path).
Followed by an adversarial review (Opus subagent) that found and fixed two
real bugs - an unvalidated player_name broadcast that let one client's
oversized name head-of-line-block the reliable channel for everyone, and a
server-side roster leak across a host/re-host cycle - plus three gaps in
the test suite itself where a claim of "verified" wasn't actually backed
by what the test checked. All five two-process smoke tests plus the
pure-function suite are green with the strengthened assertions in place.
Josh Creek