fix: Better error messages

package.json

@@ -23,6 +23,7 @@
 		"@stripe/stripe-js": "^1.52.0",
 		"@supabase/supabase-js": "^1.35.7",
 		"@types/amqplib": "^0.10.4",
+		"@types/async-retry": "^1.4.8",
 		"@types/cors": "^2.8.17",
 		"@types/mailgun-js": "^0.22.18",
 		"@types/markdown-pdf": "^9.0.5",
@@ -32,6 +33,7 @@
 		"@types/request-ip": "^0.0.41",
 		"@types/uuid": "^9.0.7",
 		"amqplib": "^0.10.3",
+		"async-retry": "^1.3.3",
 		"axios": "^1.6.2",
 		"cors": "^2.8.5",
 		"date-fns": "^2.30.0",

src/components/Demo.tsx

@@ -8,7 +8,10 @@ import { useUser } from "@/util/useUser";
 
 function alertError(email: string, e: string) {
 	alert(
-		`An unexpected error happened. Can you email [email protected] with this message (or a screenshot)?\n\nEmail: ${email}\n${e}`
+		`An unexpected error happened. Can you email [email protected] with this message (or a screenshot)?
+		
+Email: ${email}
+Error: ${e}`
 	);
 }
 
@@ -39,6 +42,7 @@ export function Demo({ onVerified }: DemoProps): React.ReactElement {
 		}
 
 		setLoading(true);
+		console.log("[/dashboard] Verifying email", email);
 		postData<CheckEmailOutput>({
 			url: `/api/v0/check_email`,
 			token: userDetails?.api_token,
@@ -51,6 +55,16 @@ export function Demo({ onVerified }: DemoProps): React.ReactElement {
 				setLoading(false);
 				return onVerified && onVerified(r);
 			})
+			.catch((err: Error) => {
+				if (err.message.includes("The result contains 0 rows")) {
+					throw new Error(
+						`The email ${email} can't be verified within 1 minute. This is because the email provider imposes obstacles to prevent real-time email verification, such as greylisting.
+Please try again later.`
+					);
+				}
+
+				throw err;
+			})
 			.catch((err: Error) => {
 				sentryException(err);
 				alertError(email, err.message);

src/pages/api/v0/check_email.ts

@@ -13,7 +13,7 @@ import { SupabaseCall } from "@/util/supabaseClient";
 import { supabaseAdmin } from "@/util/supabaseServer";
 import { WebhookExtra } from "../calls/webhook";
 
-const TIMEOUT = 60000;
+const TIMEOUT = 50000;
 const MAX_PRIORITY = 5; // Higher is faster, 5 is max.
 
 const POST = async (
@@ -37,10 +37,23 @@ const POST = async (
 	try {
 		const verificationId = v4();
 
-		const conn = await amqplib.connect(
-			process.env.RCH_AMQP_ADDR || "amqp://localhost"
-		);
-		const ch1 = await conn.createChannel();
+		const conn = await amqplib
+			.connect(process.env.RCH_AMQP_ADDR || "amqp://localhost")
+			.catch((err) => {
+				const message = `Error connecting to RabbitMQ: ${
+					(err as AggregateError).errors
+						? (err as AggregateError).errors
+								.map((e) => e.message)
+								.join(", ")
+						: err.message
+				}`;
+
+				throw new Error(message);
+			});
+
+		const ch1 = await conn.createChannel().catch((err) => {
+			throw new Error(`Error creating RabbitMQ channel: ${err.message}`);
+		});
 		const verifMethod = await getVerifMethod(req.body as CheckEmailInput);
 		const queueName = `check_email.${
 			// If the verifMethod is "Api", we use the "Headless" queue instead,
@@ -135,28 +148,32 @@ export default POST;
 // getVerifMethod returns the verifMethod that is best used to verify the
 // input's email address.
 async function getVerifMethod(input: CheckEmailInput): Promise<string> {
-	const domain = input.to_email.split("@")[1];
-	if (!domain) {
-		return "Smtp";
-	}
+	try {
+		const domain = input.to_email.split("@")[1];
+		if (!domain) {
+			return "Smtp";
+		}
 
-	const records = await dns.resolveMx(domain);
-	if (
-		input.yahoo_verif_method !== "Smtp" &&
-		records.some((r) => r.exchange.endsWith(".yahoodns.net")) // Note: there's no "." at the end of the domain.
-	) {
-		return "Headless";
-	} else if (
-		input.hotmail_verif_method !== "Smtp" &&
-		records.some((r) => r.exchange.endsWith(".protection.outlook.com")) // Note: there's no "." at the end of the domain.
-	) {
-		return "Headless";
-	} else if (
-		input.gmail_verif_method !== "Smtp" &&
-		records.some((r) => r.exchange.endsWith(".google.com")) // Note: there's no "." at the end of the domain.
-	) {
-		return "Api";
-	} else {
+		const records = await dns.resolveMx(domain);
+		if (
+			input.yahoo_verif_method !== "Smtp" &&
+			records.some((r) => r.exchange.endsWith(".yahoodns.net")) // Note: there's no "." at the end of the domain.
+		) {
+			return "Headless";
+		} else if (
+			input.hotmail_verif_method !== "Smtp" &&
+			records.some((r) => r.exchange.endsWith(".protection.outlook.com")) // Note: there's no "." at the end of the domain.
+		) {
+			return "Headless";
+		} else if (
+			input.gmail_verif_method !== "Smtp" &&
+			records.some((r) => r.exchange.endsWith(".google.com")) // Note: there's no "." at the end of the domain.
+		) {
+			return "Api";
+		} else {
+			return "Smtp";
+		}
+	} catch (err) {
 		return "Smtp";
 	}
 }

src/util/api.ts

@@ -4,7 +4,6 @@ import { addMonths, differenceInMilliseconds, parseISO } from "date-fns";
 import { NextApiRequest, NextApiResponse } from "next";
 import { RateLimiterRes } from "rate-limiter-flexible";
 
-import { setRateLimitHeaders } from "./helpers";
 import { subApiMaxCalls } from "./subs";
 import { SupabaseUser } from "./supabaseClient";
 import {
@@ -112,3 +111,32 @@ export async function checkUserInDB(
 
 	return { user, sentResponse: false };
 }
+
+/**
+ * Sets the Rate Limit headers on the response.
+ *
+ * @param res - The NextJS API response.
+ * @param rateLimiterRes - The response object from rate-limiter-flexible.
+ * @param limit - The limit per interval.
+ */
+function setRateLimitHeaders(
+	res: NextApiResponse,
+	rateLimiterRes: RateLimiterRes,
+	limit: number
+): void {
+	const headers = {
+		"Retry-After": rateLimiterRes.msBeforeNext / 1000,
+		"X-RateLimit-Limit": limit,
+		// When I first introduced rate limiting, some users had used for than
+		// 10k emails per month. Their remaining showed e.g. -8270. We decide
+		// to show 0 in these cases, hence the Math.max.
+		"X-RateLimit-Remaining": Math.max(0, rateLimiterRes.remainingPoints),
+		"X-RateLimit-Reset": new Date(
+			Date.now() + rateLimiterRes.msBeforeNext
+		).toISOString(),
+	};
+
+	Object.keys(headers).forEach((k) =>
+		res.setHeader(k, headers[k as keyof typeof headers])
+	);
+}

src/util/helpers.ts

@@ -1,6 +1,7 @@
 import axios, { AxiosError, AxiosResponse } from "axios";
 import { NextApiResponse } from "next";
 import { RateLimiterRes } from "rate-limiter-flexible";
+import retry from "async-retry";
 
 // Gets the currently depoloyed URL.
 export const getWebappURL = (): string => {
@@ -28,21 +29,33 @@ export const postData = async <T = unknown>({
 	data?: unknown;
 }): Promise<T> => {
 	try {
-		const { data: res } = await axios.post<T, AxiosResponse<T>>(url, data, {
-			headers: {
-				"Content-Type": "application/json",
-				token,
-				Authorization: token,
-			},
-			withCredentials: true,
-		});
+		return await retry(
+			async () => {
+				const { data: res } = await axios.post<T, AxiosResponse<T>>(
+					url,
+					data,
+					{
+						headers: {
+							"Content-Type": "application/json",
+							token,
+							Authorization: token,
+						},
+						withCredentials: true,
+					}
+				);
 
-		return res;
+				return res;
+			},
+			{
+				retries: 2,
+			}
+		);
 	} catch (err) {
 		throw convertAxiosError(err as AxiosError);
 	}
 };
 
+// Converts an AxiosError to a regular Error with nice formatting.
 export function convertAxiosError(err: AxiosError): Error {
 	if (err instanceof AxiosError) {
 		// Inspired by https://stackoverflow.com/questions/49967779/axios-handling-errors
@@ -87,32 +100,3 @@ export function parseHashComponents(hash: string): Record<string, string> {
 			return acc;
 		}, {} as Record<string, string>);
 }
-
-/**
- * Sets the Rate Limit headers on the response.
- *
- * @param res - The NextJS API response.
- * @param rateLimiterRes - The response object from rate-limiter-flexible.
- * @param limit - The limit per interval.
- */
-export function setRateLimitHeaders(
-	res: NextApiResponse,
-	rateLimiterRes: RateLimiterRes,
-	limit: number
-): void {
-	const headers = {
-		"Retry-After": rateLimiterRes.msBeforeNext / 1000,
-		"X-RateLimit-Limit": limit,
-		// When I first introduced rate limiting, some users had used for than
-		// 10k emails per month. Their remaining showed e.g. -8270. We decide
-		// to show 0 in these cases, hence the Math.max.
-		"X-RateLimit-Remaining": Math.max(0, rateLimiterRes.remainingPoints),
-		"X-RateLimit-Reset": new Date(
-			Date.now() + rateLimiterRes.msBeforeNext
-		).toISOString(),
-	};
-
-	Object.keys(headers).forEach((k) =>
-		res.setHeader(k, headers[k as keyof typeof headers])
-	);
-}

yarn.lock

@@ -1960,6 +1960,13 @@
   dependencies:
     "@types/node" "*"
 
+"@types/async-retry@^1.4.8":
+  version "1.4.8"
+  resolved "https://registry.yarnpkg.com/@types/async-retry/-/async-retry-1.4.8.tgz#eb32df13aceb9ba1a8a80e7fe518ff4e3fe46bb3"
+  integrity sha512-Qup/B5PWLe86yI5I3av6ePGaeQrIHNKCwbsQotD6aHQ6YkHsMUxVZkZsmx/Ry3VZQ6uysHwTjQ7666+k6UjVJA==
+  dependencies:
+    "@types/retry" "*"
+
 "@types/async@^3.2.16":
   version "3.2.18"
   resolved "https://registry.yarnpkg.com/@types/async/-/async-3.2.18.tgz#3d93dde6eab654f7bc23e549d9af5d3fa4a5bdc5"
@@ -2178,6 +2185,11 @@
   dependencies:
     "@types/node" "*"
 
+"@types/retry@*":
+  version "0.12.5"
+  resolved "https://registry.yarnpkg.com/@types/retry/-/retry-0.12.5.tgz#f090ff4bd8d2e5b940ff270ab39fd5ca1834a07e"
+  integrity sha512-3xSjTp3v03X/lSQLkczaN9UIEwJMoMCA1+Nb5HfbJEQWogdeQIyVtTvxPXDQjZ5zws8rFQfVfRdz03ARihPJgw==
+
 "@types/scheduler@*":
   version "0.16.2"
   resolved "https://registry.yarnpkg.com/@types/scheduler/-/scheduler-0.16.2.tgz#1a62f89525723dde24ba1b01b092bf5df8ad4d39"
@@ -2729,6 +2741,13 @@ astring@^1.6.0:
   resolved "https://registry.yarnpkg.com/astring/-/astring-1.8.4.tgz#6d4c5d8de7be2ead9e4a3cc0e2efb8d759378904"
   integrity sha512-97a+l2LBU3Op3bBQEff79i/E4jMD2ZLFD8rHx9B6mXyB2uQwhJQYfiDqUwtfjF4QA1F2qs//N6Cw8LetMbQjcw==
 
+async-retry@^1.3.3:
+  version "1.3.3"
+  resolved "https://registry.yarnpkg.com/async-retry/-/async-retry-1.3.3.tgz#0e7f36c04d8478e7a58bdbed80cedf977785f280"
+  integrity sha512-wfr/jstw9xNi/0teMHrRW7dsz3Lt5ARhYNZ2ewpadnhaIp5mbALhOAP+EAdsC7t4Z6wqsDVv9+W6gm1Dk9mEyw==
+  dependencies:
+    retry "0.13.1"
+
 async-sema@^3.1.1:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/async-sema/-/async-sema-3.1.1.tgz#e527c08758a0f8f6f9f15f799a173ff3c40ea808"
@@ -7682,6 +7701,11 @@ restore-cursor@^3.1.0:
     onetime "^5.1.0"
     signal-exit "^3.0.2"
 
+[email protected]:
+  version "0.13.1"
+  resolved "https://registry.yarnpkg.com/retry/-/retry-0.13.1.tgz#185b1587acf67919d63b357349e03537b2484658"
+  integrity sha512-XQBQ3I8W1Cge0Seh+6gjj03LbmRFWuoszgK9ooCpwYIrhhoO80pfq4cUkU5DkknwfOfFteRwlZ56PYOGYyFWdg==
+
 reusify@^1.0.4:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/reusify/-/reusify-1.0.4.tgz#90da382b1e126efc02146e90845a88db12925d76"