fix(email): respect hosts file for SMTP connections

Author: 0xSysR3ll

next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/dev/types/routes.d.ts";
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/pages/api-reference/config/typescript for more information.

server/lib/email/index.ts

@@ -1,10 +1,44 @@
 import type { NotificationAgentEmail } from '@server/lib/settings';
 import { getSettings } from '@server/lib/settings';
 import Email from 'email-templates';
+import net from 'node:net';
 import nodemailer from 'nodemailer';
+import type SMTPTransport from 'nodemailer/lib/smtp-transport';
 import { URL } from 'url';
 import { openpgpEncrypt } from './openpgpEncrypt';
 
+const getSocket: SMTPTransport.Options['getSocket'] = (options, callback) => {
+  const socket = net.connect({
+    host: options.host ?? 'localhost',
+    port: options.port ?? 587,
+    localAddress: options.localAddress,
+  });
+  const cleanup = () => {
+    socket.setTimeout(0);
+    socket.removeListener('error', onError);
+    socket.removeListener('connect', onConnect);
+    socket.removeListener('timeout', onTimeout);
+  };
+  const onError = (error: Error) => {
+    cleanup();
+    callback(error, undefined);
+  };
+  const onConnect = () => {
+    cleanup();
+    callback(null, { connection: socket });
+  };
+  const onTimeout = () => {
+    cleanup();
+    socket.destroy();
+    callback(new Error('SMTP connection timed out'), undefined);
+  };
+
+  socket.once('error', onError);
+  socket.once('connect', onConnect);
+  socket.once('timeout', onTimeout);
+  socket.setTimeout(10000);
+};
+
 class PreparedEmail extends Email {
   public constructor(settings: NotificationAgentEmail, pgpKey?: string) {
     const { applicationUrl } = getSettings().main;
@@ -28,6 +62,7 @@ class PreparedEmail extends Email {
               pass: settings.options.authPass,
             }
           : undefined,
+      getSocket: net.isIP(settings.options.smtpHost) ? undefined : getSocket,
     });
 
     if (pgpKey) {