feat: Message Rate Limiters, Violation Logging, & Ban System 🔨 (#903)

* refactor: require Auth middleware in route index files

* feat: concurrent message limiter

* feat: complete concurrent message limiter with caching

* refactor: SSE response methods separated from handleText

* fix(abortMiddleware): fix req and res order to standard, use endpointOption in req.body

* chore: minor name changes

* refactor: add isUUID condition to saveMessage

* fix(concurrentLimiter): logic correctly handles the max number of concurrent messages and res closing/finalization

* chore: bump keyv and remove console.log from Message

* fix(concurrentLimiter): ensure messages are only saved in later message children

* refactor(concurrentLimiter): use KeyvFile instead, could make other stores configurable in the future

* feat: add denyRequest function for error responses

* feat(utils): add isStringTruthy function

Introduce the isStringTruthy function to the utilities module to check if a string value is a case-insensitive match for 'true'

* feat: add optional message rate limiters by IP and userId

* feat: add optional message rate limiters by IP and userId to edit route

* refactor: rename isStringTruthy to isTrue for brevity

* refactor(getError): use map to make code cleaner

* refactor: use memory for concurrent rate limiter to prevent clearing on startup/exit, add multiple log files, fix error message for concurrent violation

* feat: check if errorMessage is object, stringify if so

* chore: send object to denyRequest which will stringify it

* feat: log excessive requests

* fix(getError): correctly pluralize messages

* refactor(limiters): make type consistent between logs and errorMessage

* refactor(cache): move files out of lib/db into separate cache dir
>> feat: add getLogStores function so Keyv instance is not redundantly created on every violation
feat: separate violation logging to own function with logViolation

* fix: cache/index.js export, properly record userViolations

* refactor(messageLimiters): use new logging method, add logging to registrations

* refactor(logViolation): make userLogs an array of logs per user

* feat: add logging to login limiter

* refactor: pass req as first param to logViolation and record offending IP

* refactor: rename isTrue helper fn to isEnabled

* feat: add simple non_browser check and log violation

* fix: open handles in unit tests, remove KeyvMongo as not used and properly mock global fetch

* chore: adjust nodemon ignore paths to properly ignore logs

* feat: add math helper function for safe use of eval

* refactor(api/convos): use middleware at top of file to avoid redundancy

* feat: add delete all static method for Sessions

* fix: redirect to login on refresh if user is not found, or the session is not found but hasn't expired (ban case)

* refactor(getLogStores): adjust return type

* feat: add ban violation and check ban logic
refactor(logViolation): pass both req and res objects

* feat: add removePorts helper function

* refactor: rename getError to getMessageError and add getLoginError for displaying different login errors

* fix(AuthContext): fix type issue and remove unused code

* refactor(bans): ban by ip and user id, send response based on origin

* chore: add frontend ban messages

* refactor(routes/oauth): add ban check to handler, also consolidate logic to avoid redundancy

* feat: add ban check to AI messaging routes

* feat: add ban check to login/registration

* fix(ci/api): mock KeyvMongo to avoid tests hanging

* docs: update .env.example
> refactor(banViolation): calculate interval rate crossover, early return if duration is invalid
ci(banViolation): add tests to ensure users are only banned when expected

* docs: improve wording for mod system

* feat: add configurable env variables for violation scores

* chore: add jsdoc for uaParser.js

* chore: improve ban text log

* chore: update bun test scripts

* refactor(math.js): add fallback values

* fix(KeyvMongo/banLogs): refactor keyv instances to top of files to avoid memory leaks, refactor ban logic to use getLogStores instead
refactor(getLogStores): get a single log store by type

* fix(ci): refactor tests due to banLogs changes, also make sure to clear and revoke sessions even if ban duration is 0

* fix(banViolation.js): getLogStores import

* feat: handle 500 code error at login

* fix(middleware): handle case where user.id is _id and not just id

* ci: add ban secrets for backend unit tests

* refactor: logout user upon ban

* chore: log session delete message only if deletedCount > 0

* refactor: change default ban duration (2h) and make logic more clear in JSDOC

* fix: login and registration limiters will now return rate limiting error

* fix: userId not parsable as non ObjectId string

* feat: add useTimeout hook to properly clear timeouts when invoking functions within them
refactor(AuthContext): cleanup code by using new hook and defining types in ~/common

* fix: login error message for rate limits

* docs: add info for automated mod system and rate limiters, update other docs accordingly

* chore: bump data-provider version

api/server/middleware/concurrentLimiter.js

@@ -0,0 +1,81 @@
+const Keyv = require('keyv');
+const { logViolation } = require('../../cache');
+
+const denyRequest = require('./denyRequest');
+
+// Serve cache from memory so no need to clear it on startup/exit
+const pendingReqCache = new Keyv({ namespace: 'pendingRequests' });
+
+/**
+ * Middleware to limit concurrent requests for a user.
+ *
+ * This middleware checks if a user has exceeded a specified concurrent request limit.
+ * If the user exceeds the limit, an error is returned. If the user is within the limit,
+ * their request count is incremented. After the request is processed, the count is decremented.
+ * If the `pendingReqCache` store is not available, the middleware will skip its logic.
+ *
+ * @function
+ * @param {Object} req - Express request object containing user information.
+ * @param {Object} res - Express response object.
+ * @param {function} next - Express next middleware function.
+ * @throws {Error} Throws an error if the user exceeds the concurrent request limit.
+ */
+const concurrentLimiter = async (req, res, next) => {
+  if (!pendingReqCache) {
+    return next();
+  }
+
+  if (Object.keys(req?.body ?? {}).length === 1 && req?.body?.abortKey) {
+    return next();
+  }
+
+  const { CONCURRENT_MESSAGE_MAX = 1, CONCURRENT_VIOLATION_SCORE: score } = process.env;
+  const limit = Math.max(CONCURRENT_MESSAGE_MAX, 1);
+  const type = 'concurrent';
+
+  const userId = req.user?.id ?? req.user?._id ?? null;
+  const pendingRequests = (await pendingReqCache.get(userId)) ?? 0;
+
+  if (pendingRequests >= limit) {
+    const errorMessage = {
+      type,
+      limit,
+      pendingRequests,
+    };
+
+    await logViolation(req, res, type, errorMessage, score);
+    return await denyRequest(req, res, errorMessage);
+  } else {
+    await pendingReqCache.set(userId, pendingRequests + 1);
+  }
+
+  // Ensure the requests are removed from the store once the request is done
+  const cleanUp = async () => {
+    if (!pendingReqCache) {
+      return;
+    }
+
+    const currentRequests = await pendingReqCache.get(userId);
+
+    if (currentRequests && currentRequests >= 1) {
+      await pendingReqCache.set(userId, currentRequests - 1);
+    } else {
+      await pendingReqCache.delete(userId);
+    }
+  };
+
+  if (pendingRequests < limit) {
+    res.on('finish', cleanUp);
+    res.on('close', cleanUp);
+  }
+
+  next();
+};
+
+// if cache is not served from memory, clear it on exit
+// process.on('exit', async () => {
+//   console.log('Clearing all pending requests before exiting...');
+//   await pendingReqCache.clear();
+// });
+
+module.exports = concurrentLimiter;