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sec(server): restrict custom names for guest players and validate lobby ID endpoints (#1636) #4018

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sec(server): restrict custom names for guest players and validate lobby ID endpoints (#1636) #4018

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dd8b705
sec(server): restrict custom names for guest players and validate lob…
berkelmali May 26, 2026
6d3e4ae
fix(server): resolve TS compilation error in rejoin union type matching
berkelmali May 26, 2026
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27 changes: 24 additions & 3 deletions src/server/Worker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ import { GameEnv } from "../core/configuration/Config";
import { GameType } from "../core/game/Game";
import {
ClientMessageSchema,
GAME_ID_REGEX,
GameID,
PartialGameRecordSchema,
ServerErrorMessage,
Expand Down Expand Up @@ -140,6 +141,9 @@ export async function startWorker() {

app.post("/api/create_game/:id", async (req, res) => {
const id = req.params.id;
if (!GAME_ID_REGEX.test(id)) {
return res.status(400).json({ error: "Invalid game ID format" });
}

// Extract persistentID from Authorization header token
// Never accept persistentID directly from client
Expand Down Expand Up @@ -209,15 +213,22 @@ export async function startWorker() {

app.get("/api/game/:id/exists", async (req, res) => {
const lobbyId = req.params.id;
if (!GAME_ID_REGEX.test(lobbyId)) {
return res.status(400).json({ error: "Invalid game ID format" });
}
res.json({
exists: gm.game(lobbyId) !== null,
});
});

app.get("/api/game/:id", async (req, res) => {
const game = gm.game(req.params.id);
const id = req.params.id;
if (!GAME_ID_REGEX.test(id)) {
return res.status(400).json({ error: "Invalid game ID format" });
}
const game = gm.game(id);
if (game === null) {
log.info(`lobby ${req.params.id} not found`);
log.info(`lobby ${id} not found`);
return res.status(404).json({ error: "Game not found" });
}
res.json(game.gameInfo());
Expand Down Expand Up @@ -359,11 +370,21 @@ export async function startWorker() {
// Normalize username and clan tag before any rejoin/join handling.
// If this connection maps to an existing lobby client, we still want
// the latest pre-join identity to be reflected.
const { clanTag: censoredClanTag, username: censoredUsername } =
let { clanTag: censoredClanTag, username: censoredUsername } =
privilegeRefresher
.get()
.censor(clientMsg.username, clientMsg.clanTag ?? null);

if (claims === null) {
// If the user is unauthenticated (anonymous guest), generate a deterministic guest name.
// Clan tag is cleared for guests to prevent impersonation.
const cleanUuid = persistentId.replace(/-/g, "").toLowerCase();
const decimal = BigInt(`0x${cleanUuid}`);
const threeDigits = decimal % 1000n;
censoredUsername = "Anon" + threeDigits.toString().padStart(3, "0");
censoredClanTag = null;
}

// Try to reconnect an existing client (e.g., page refresh)
// If successful, skip all authorization
if (
Expand Down
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