The server code learns to distrust strangers: a 64KB WebSocket payload
cap (the ws default is 100MB — an easy OOM on a 1GB droplet), a
per-connection token-bucket rate limit, caps on concurrent sockets,
total rooms, rooms per connection, pending transfer codes, and seats
per myGames query. Player names are stripped of control characters
and bounded at 24 chars, room codes at 8, serialized commands at
16KB before they touch the append-only log. Catch-up replays — a
full game rebuild per request — get a 3-second cooldown. Unexpected
exceptions now log server-side and send strangers a bare "internal
error" instead of the exception text.
One real bug found by the sweep: myGames compared the client's raw
seat token against the stored hash, so the lobby ledger silently
matched nothing since tokens were hashed at rest — and the comparison
wasn't timing-safe either. It now goes through the same timingSafeEqual
path as every other seat check, via a new exported seatTokenValid.
The droplet tightens too: the game server binds loopback (HOST env)
so port 8787 no longer answers the internet — it was reachable
directly, plaintext, bypassing Caddy — and ufw now allows only ssh,
80, and 443. The systemd unit gains a sandbox (ProtectSystem=strict,
ProtectHome, NoNewPrivileges, PrivateTmp, MemoryMax=700M so a runaway
process is killed and restarted before it takes the box down) and
execs tsx directly instead of through npx. Caddy adds HSTS, nosniff,
frame-denial, and no-referrer headers; setup-droplet.sh records all
of it for future rebuilds.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Eric WagonerandClaude Fable 5
f0a264147f