Harden room discovery and health metrics

server/ops.js

@@ -0,0 +1,76 @@
+import crypto from 'crypto';
+
+export function checkCooldown(cooldowns, key, windowMs, now = Date.now()) {
+    const lastAllowedAt = cooldowns.get(key) || 0;
+    if (now - lastAllowedAt < windowMs) {
+        return false;
+    }
+    cooldowns.set(key, now);
+    return true;
+}
+
+export function isAdminMetricsAuthorized(authHeader, adminToken) {
+    if (!adminToken || typeof adminToken !== 'string') return false;
+    if (!authHeader || typeof authHeader !== 'string') return false;
+
+    const prefix = 'Bearer ';
+    if (!authHeader.startsWith(prefix)) return false;
+
+    const provided = authHeader.slice(prefix.length);
+    if (!provided) return false;
+
+    const expectedBuffer = Buffer.from(adminToken);
+    const providedBuffer = Buffer.from(provided);
+
+    if (expectedBuffer.length !== providedBuffer.length) return false;
+    return crypto.timingSafeEqual(expectedBuffer, providedBuffer);
+}
+
+export function buildHealthPayload({
+    rooms,
+    connections,
+    includeMetrics = false,
+    now = Date.now(),
+    uptime = 0,
+    memoryUsage = () => process.memoryUsage(),
+    rateLimitSizes = {}
+}) {
+    const payload = {
+        status: 'ok',
+        uptime,
+        rooms: rooms.size,
+        connections,
+        timestamp: now
+    };
+
+    if (!includeMetrics) return payload;
+
+    const roomValues = Array.from(rooms.values());
+    const roomSizes = roomValues.map(room => room.peers?.size || 0);
+    const peers = roomSizes.reduce((sum, size) => sum + size, 0);
+    const maxPeersInRoom = roomSizes.length > 0 ? Math.max(...roomSizes) : 0;
+    const avgPeersPerRoom = roomSizes.length > 0
+        ? Math.round((peers / roomSizes.length) * 100) / 100
+        : 0;
+    const mem = memoryUsage();
+
+    return {
+        ...payload,
+        peers,
+        roomsWithLobby: roomValues.filter(room => !!room.activeLobby).length,
+        avgPeersPerRoom,
+        maxPeersInRoom,
+        rateLimitEntries: {
+            connections: rateLimitSizes.connections || 0,
+            events: rateLimitSizes.events || 0,
+            health: rateLimitSizes.health || 0,
+            authFailures: rateLimitSizes.authFailures || 0,
+            roomList: rateLimitSizes.roomList || 0
+        },
+        memory: {
+            rss: mem.rss,
+            heapUsed: mem.heapUsed,
+            heapTotal: mem.heapTotal
+        }
+    };
+}