From d72e113570cc64566052d6c3cf064b9476a99fb5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=BCseyin=20Berke=20B=C3=BCt=C3=BCn?=
 <8071263+Zamion101@users.noreply.github.com>
Date: Sat, 24 Dec 2022 23:36:58 +0100
Subject: [PATCH] feat: Patch Router#handle to catch Promise Rejection

In order to catch Promise rejections inside and outside of middlewares
as well as in route logic we need to patch `Router#handle` and add
.catch() to the function. With that addition it is possible to
catch rejections and handle inside `requestErrorHandler` middleware.
---
 backend/src/app.ts                    |  6 ++-
 backend/src/config/index.ts           |  2 +-
 backend/src/utils/patchAsyncRoutes.js | 65 +++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 3 deletions(-)
 create mode 100644 backend/src/utils/patchAsyncRoutes.js

diff --git a/backend/src/app.ts b/backend/src/app.ts
index af88105fdc..e49551a912 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -1,4 +1,5 @@
 
+import { patchRouterParam } from './utils/patchAsyncRoutes';
 import express from 'express';
 import helmet from 'helmet';
 import cors from 'cors';
@@ -30,9 +31,11 @@ import {
 } from './routes';
 import { getLogger } from './utils/logger';
 import { RouteNotFoundError } from './utils/errors';
-import { errorHandler } from '@sentry/node/types/handlers';
 import { requestErrorHandler } from './middleware/requestErrorHandler';
 
+//* Patch Async route params to handle Promise Rejections
+patchRouterParam()
+
 export const app = express();
 
 app.enable('trust proxy');
@@ -53,7 +56,6 @@ if (NODE_ENV === 'production') {
   app.use(helmet());
 }
 
-
 // routers
 app.use('/api/v1/signup', signupRouter);
 app.use('/api/v1/auth', authRouter);
diff --git a/backend/src/config/index.ts b/backend/src/config/index.ts
index 121a0aad01..8d621c67fc 100644
--- a/backend/src/config/index.ts
+++ b/backend/src/config/index.ts
@@ -10,7 +10,7 @@ const JWT_SIGNUP_LIFETIME = process.env.JWT_SIGNUP_LIFETIME! || '15m';
 const JWT_SIGNUP_SECRET = process.env.JWT_SIGNUP_SECRET!;
 const MONGO_URL = process.env.MONGO_URL!;
 const NODE_ENV = process.env.NODE_ENV! || 'production';
-const VERBOSE_ERROR_OUTPUT = process.env.VERBOSE_ERROR_OUTPUT! !== 'true' && true;
+const VERBOSE_ERROR_OUTPUT = process.env.VERBOSE_ERROR_OUTPUT! === 'true' && true;
 const LOKI_HOST = process.env.LOKI_HOST || undefined;
 const CLIENT_SECRET_HEROKU = process.env.CLIENT_SECRET_HEROKU!;
 const CLIENT_ID_HEROKU = process.env.CLIENT_ID_HEROKU!;
diff --git a/backend/src/utils/patchAsyncRoutes.js b/backend/src/utils/patchAsyncRoutes.js
new file mode 100644
index 0000000000..6f6d2367f7
--- /dev/null
+++ b/backend/src/utils/patchAsyncRoutes.js
@@ -0,0 +1,65 @@
+/*
+Original work Copyright (c) 2016, Nikolay Nemshilov <nemshilov@gmail.com>
+Modified work Copyright (c) 2016, David Banham <david@banham.id.au>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+
+*/
+
+/* eslint-disable @typescript-eslint/no-var-requires */
+/* eslint-env node */
+const Layer = require('express/lib/router/layer');
+const Router = require('express/lib/router');
+
+const last = (arr = []) => arr[arr.length - 1];
+const noop = Function.prototype;
+
+function copyFnProps(oldFn, newFn) {
+  Object.keys(oldFn).forEach((key) => {
+    newFn[key] = oldFn[key];
+  });
+  return newFn;
+}
+
+function wrap(fn) {
+  const newFn = function newFn(...args) {
+    const ret = fn.apply(this, args);
+    const next = (args.length === 5 ? args[2] : last(args)) || noop;
+    if (ret && ret.catch) ret.catch(err => next(err));
+    return ret;
+  };
+  Object.defineProperty(newFn, 'length', {
+    value: fn.length,
+    writable: false,
+  });
+  return copyFnProps(fn, newFn);
+}
+
+export function patchRouterParam() {
+  const originalParam = Router.prototype.constructor.param;
+  Router.prototype.constructor.param = function param(name, fn) {
+    fn = wrap(fn);
+    return originalParam.call(this, name, fn);
+  };
+}
+
+Object.defineProperty(Layer.prototype, 'handle', {
+  enumerable: true,
+  get() {
+    return this.__handle;
+  },
+  set(fn) {
+    fn = wrap(fn);
+    this.__handle = fn;
+  },
+});
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