Cache token for thundering hurd

server/private/lib/cache.ts

@@ -1,3 +1,16 @@
+/*
+ * This file is part of a proprietary work.
+ *
+ * Copyright (c) 2025 Fossorial, Inc.
+ * All rights reserved.
+ *
+ * This file is licensed under the Fossorial Commercial License.
+ * You may not use this file except in compliance with the License.
+ * Unauthorized use, copying, modification, or distribution is strictly prohibited.
+ *
+ * This file is not licensed under the AGPLv3.
+ */
+
 import NodeCache from "node-cache";
 import logger from "@server/logger";
 import { redisManager } from "@server/private/lib/redis";

server/private/lib/tokenCache.ts

@@ -0,0 +1,77 @@
+/*
+ * This file is part of a proprietary work.
+ *
+ * Copyright (c) 2025 Fossorial, Inc.
+ * All rights reserved.
+ *
+ * This file is licensed under the Fossorial Commercial License.
+ * You may not use this file except in compliance with the License.
+ * Unauthorized use, copying, modification, or distribution is strictly prohibited.
+ *
+ * This file is not licensed under the AGPLv3.
+ */
+
+import redisManager from "#dynamic/lib/redis";
+import { encrypt, decrypt } from "@server/lib/crypto";
+import logger from "@server/logger";
+
+/**
+ * Returns a cached plaintext token from Redis if one exists and decrypts
+ * cleanly, otherwise calls `createSession` to mint a fresh token, stores the
+ * encrypted value in Redis with the given TTL, and returns it.
+ *
+ * Failures at the Redis layer are non-fatal – the function always falls
+ * through to session creation so the caller is never blocked by a Redis outage.
+ *
+ * @param cacheKey   Unique Redis key, e.g. `"newt:token_cache:abc123"`
+ * @param secret     Server secret used for AES encryption/decryption
+ * @param ttlSeconds Cache TTL in seconds (should match session expiry)
+ * @param createSession Factory that mints a new session and returns its raw token
+ */
+export async function getOrCreateCachedToken(
+    cacheKey: string,
+    secret: string,
+    ttlSeconds: number,
+    createSession: () => Promise<string>
+): Promise<string> {
+    if (redisManager.isRedisEnabled()) {
+        try {
+            const cached = await redisManager.get(cacheKey);
+            if (cached) {
+                const token = decrypt(cached, secret);
+                if (token) {
+                    logger.debug(`Token cache hit for key: ${cacheKey}`);
+                    return token;
+                }
+                // Decryption produced an empty string – treat as a miss
+                logger.warn(
+                    `Token cache decryption returned empty string for key: ${cacheKey}, treating as miss`
+                );
+            }
+        } catch (e) {
+            logger.warn(
+                `Token cache read/decrypt failed for key ${cacheKey}, falling through to session creation:`,
+                e
+            );
+        }
+    }
+
+    const token = await createSession();
+
+    if (redisManager.isRedisEnabled()) {
+        try {
+            const encrypted = encrypt(token, secret);
+            await redisManager.set(cacheKey, encrypted, ttlSeconds);
+            logger.debug(
+                `Token cached in Redis for key: ${cacheKey} (TTL ${ttlSeconds}s)`
+            );
+        } catch (e) {
+            logger.warn(
+                `Token cache write failed for key ${cacheKey} (session was still created):`,
+                e
+            );
+        }
+    }
+
+    return token;
+}