feat: added more DNS error handling

Author: niftylettuce

README.md

@@ -199,7 +199,7 @@ function middleware(ctx) {
 
 If you specify `app.context.api = true` or set `ctx.api = true`, and if a Mongoose validation error message occurs that has more than one message (e.g. multiple fields were invalid) – then `err.message` will be joined by a comma instead of by `<li>`.
 
-Therefore if you _DO_ want your API error messages to return HTML formatted error lists for Mongoose validation, then set `app.context.api = false`, `ctx.api = false`, or simply make sure to not set them before using this error handler.
+Therefore if you *DO* want your API error messages to return HTML formatted error lists for Mongoose validation, then set `app.context.api = false`, `ctx.api = false`, or simply make sure to not set them before using this error handler.
 
 ```js
 try {
@@ -244,7 +244,7 @@ You can also specify a base URI in the environment variable for rendering as `pr
 [MIT](LICENSE) © [Nick Baugh](http://niftylettuce.com/)
 
 
-## 
+##
 
 [boom]: https://github.com/hapijs/boom
 

examples/api.js

@@ -20,8 +20,8 @@ app.use(koa404Handler);
 const router = new Router();
 
 // throw an error anywhere you want!
-router.get('/404', ctx => ctx.throw(404));
-router.get('/500', ctx => ctx.throw(500));
+router.get('/404', (ctx) => ctx.throw(404));
+router.get('/500', (ctx) => ctx.throw(500));
 
 // initialize routes on the app
 app.use(router.routes());

examples/web-app.js

@@ -18,7 +18,7 @@ app.keys = ['foo', 'bar'];
 // initialize redis store
 const redisClient = redis.createClient();
 redisClient.on('connect', () => app.emit('log', 'info', 'redis connected'));
-redisClient.on('error', err => app.emit('error', err));
+redisClient.on('error', (err) => app.emit('error', err));
 
 // define our storage
 const redisStore = new RedisStore({
@@ -47,8 +47,8 @@ app.use(koa404Handler);
 const router = new Router();
 
 // throw an error anywhere you want!
-router.get('/404', ctx => ctx.throw(404));
-router.get('/500', ctx => ctx.throw(500));
+router.get('/404', (ctx) => ctx.throw(404));
+router.get('/500', (ctx) => ctx.throw(500));
 
 // initialize routes on the app
 app.use(router.routes());

index.js

@@ -12,14 +12,41 @@ const statuses = require('statuses');
 const toIdentifier = require('toidentifier');
 
 // lodash
+const _isError = require('lodash.iserror');
+const _isFunction = require('lodash.isfunction');
 const _isNumber = require('lodash.isnumber');
-const _isString = require('lodash.isstring');
 const _isObject = require('lodash.isobject');
-const _isFunction = require('lodash.isfunction');
-const _isError = require('lodash.iserror');
+const _isString = require('lodash.isstring');
 const _map = require('lodash.map');
 const _values = require('lodash.values');
 
+// NOTE: if you change this, be sure to sync in `forward-email`
+// <https://github.com/nodejs/node/blob/08dd4b1723b20d56fbedf37d52e736fe09715f80/lib/dns.js#L296-L320>
+const CODES_TO_RESPONSE_CODES = {
+  EADDRGETNETWORKPARAMS: 421,
+  EADDRINUSE: 421,
+  EAI_AGAIN: 421,
+  EBADFLAGS: 421,
+  EBADHINTS: 421,
+  ECANCELLED: 421,
+  ECONNREFUSED: 421,
+  ECONNRESET: 442,
+  EDESTRUCTION: 421,
+  EFORMERR: 421,
+  ELOADIPHLPAPI: 421,
+  ENETUNREACH: 421,
+  ENODATA: 421,
+  ENOMEM: 421,
+  ENOTFOUND: 421,
+  ENOTINITIALIZED: 421,
+  EPIPE: 421,
+  EREFUSED: 421,
+  ESERVFAIL: 421,
+  ETIMEOUT: 420
+};
+
+const RETRY_CODES = Object.keys(CODES_TO_RESPONSE_CODES);
+
 const opts = {
   encoding: 'utf8'
 };
@@ -81,8 +108,13 @@ function errorHandler(
 
     // check if we have a boom error that specified
     // a status code already for us (and then use it)
-    if (_isObject(err.output) && _isNumber(err.output.statusCode))
+    if (_isObject(err.output) && _isNumber(err.output.statusCode)) {
       err.status = err.output.statusCode;
+    } else if (_isString(err.code) && RETRY_CODES.includes(err.code)) {
+      // check if this was a DNS error and if so
+      // then set status code for retries appropriately
+      err.status = CODES_TO_RESPONSE_CODES[err.code];
+    }
 
     if (!_isNumber(err.status)) err.status = 500;
 
@@ -186,7 +218,6 @@ function errorHandler(
               this.cookies.set(cookiesKey, this.sessionId, this.session.cookie);
             } catch (err) {
               logger.error(err);
-              // eslint-disable-next-line max-depth
               if (err.code === 'ERR_HTTP_HEADERS_SENT') return;
             }
           }

package.json

@@ -36,12 +36,13 @@
     }
   ],
   "dependencies": {
-    "@hapi/boom": "^9.1.0",
-    "camelcase": "^6.0.0",
+    "@hapi/boom": "^9.1.1",
+    "ava": "3.11.1",
+    "camelcase": "^6.2.0",
     "capitalize": "^2.0.3",
     "co": "^4.6.0",
     "fast-safe-stringify": "^2.0.7",
-    "html-to-text": "^5.1.1",
+    "html-to-text": "5",
     "humanize-string": "^2.1.0",
     "lodash.iserror": "^3.1.1",
     "lodash.isfunction": "^3.0.9",
@@ -50,35 +51,34 @@
     "lodash.isstring": "^4.0.1",
     "lodash.map": "^4.6.0",
     "lodash.values": "^4.3.0",
-    "statuses": "^2.0.0",
+    "statuses": "^2.0.1",
     "toidentifier": "^1.0.0"
   },
   "devDependencies": {
-    "@commitlint/cli": "^9.1.2",
-    "@commitlint/config-conventional": "^9.1.2",
-    "@koa/router": "^9.4.0",
-    "ava": "3.11.1",
-    "codecov": "^3.7.2",
-    "cross-env": "^7.0.2",
-    "eslint-config-xo-lass": "^1.0.3",
-    "fixpack": "^3.0.6",
-    "husky": "^4.2.5",
-    "koa": "^2.13.0",
+    "@commitlint/cli": "^11.0.0",
+    "@commitlint/config-conventional": "^11.0.0",
+    "@koa/router": "^10.0.0",
+    "codecov": "^3.8.1",
+    "cross-env": "^7.0.3",
+    "eslint-config-xo-lass": "^1.0.5",
+    "fixpack": "^4.0.0",
+    "husky": "^5.0.9",
+    "koa": "^2.13.1",
     "koa-404-handler": "^0.0.2",
     "koa-basic-auth": "^4.0.0",
     "koa-connect-flash": "^0.1.2",
-    "koa-convert": "^1.2.0",
-    "koa-generic-session": "^2.0.4",
+    "koa-convert": "^2.0.0",
+    "koa-generic-session": "^2.1.1",
     "koa-redis": "^4.0.1",
-    "lint-staged": "^10.2.11",
+    "lint-staged": "^10.5.4",
     "lodash": "^4.17.20",
     "nyc": "^15.1.0",
     "redis": "^3.0.2",
-    "remark-cli": "^8.0.1",
-    "remark-preset-github": "^3.0.0",
+    "remark-cli": "^9.0.0",
+    "remark-preset-github": "^4.0.1",
     "rimraf": "^3.0.2",
-    "supertest": "^4.0.2",
-    "xo": "^0.33.0"
+    "supertest": "^6.1.3",
+    "xo": "^0.37.1"
   },
   "engines": {
     "node": ">= 10.14"