Fallback to dns.resolve4/6 on getaddrinfo failure

ts/textsecure/WebAPI.ts

@@ -28,6 +28,7 @@ import { formatAcceptLanguageHeader } from '../util/userLanguages';
 import { toWebSafeBase64, fromWebSafeBase64 } from '../util/webSafeBase64';
 import { getBasicAuth } from '../util/getBasicAuth';
 import { isPnpEnabled } from '../util/isPnpEnabled';
+import { lookupWithFallback } from '../util/dns';
 import type { SocketStatus } from '../types/SocketStatus';
 import { toLogFormat } from '../types/errors';
 import { isPackIdValid, redactPackId } from '../types/Stickers';
@@ -243,6 +244,7 @@ async function _promiseAjax(
       agent: proxyUrl
         ? new ProxyAgent(proxyUrl)
         : new Agent({
+            lookup: lookupWithFallback,
             keepAlive: !options.disableSessionResumption,
             maxCachedSessions: options.disableSessionResumption ? 0 : undefined,
           }),

ts/textsecure/WebSocket.ts

@@ -10,6 +10,7 @@ import { strictAssert } from '../util/assert';
 import { explodePromise } from '../util/explodePromise';
 import { getUserAgent } from '../util/getUserAgent';
 import * as durations from '../util/durations';
+import { lookupWithFallback } from '../util/dns';
 import * as log from '../logging/log';
 import * as Timers from '../Timers';
 import { ConnectTimeoutError, HTTPError } from './Errors';
@@ -55,6 +56,7 @@ export function connect<Resource extends IResource>({
     tlsOptions: {
       ca: certificateAuthority,
       agent: proxyAgent,
+      lookup: lookupWithFallback,
     },
     maxReceivedFrameSize: 0x210000,
   });

ts/updater/got.ts

@@ -8,6 +8,7 @@ import ProxyAgent from 'proxy-agent';
 import * as packageJson from '../../package.json';
 import { getUserAgent } from '../util/getUserAgent';
 import * as durations from '../util/durations';
+import { lookupWithFallback } from '../util/dns';
 
 export const GOT_CONNECT_TIMEOUT = durations.MINUTE;
 export const GOT_LOOKUP_TIMEOUT = durations.MINUTE;
@@ -37,6 +38,7 @@ export function getGotOptions(): GotOptions {
     https: {
       certificateAuthority,
     },
+    lookup: lookupWithFallback as GotOptions['lookup'],
     headers: {
       'Cache-Control': 'no-cache',
       'User-Agent': getUserAgent(packageJson.version),

ts/util/dns.ts

@@ -0,0 +1,62 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { lookup as nativeLookup, resolve4, resolve6 } from 'dns';
+import type { LookupOneOptions } from 'dns';
+
+import * as log from '../logging/log';
+import * as Errors from '../types/errors';
+import { strictAssert } from './assert';
+
+export function lookupWithFallback(
+  hostname: string,
+  opts: LookupOneOptions,
+  callback: (
+    err: NodeJS.ErrnoException | null,
+    address: string,
+    family: number
+  ) => void
+): void {
+  // Node.js support various signatures, but we only support one.
+  strictAssert(typeof opts === 'object', 'missing options');
+  strictAssert(Boolean(opts.all) !== true, 'options.all is not supported');
+  strictAssert(typeof callback === 'function', 'missing callback');
+
+  nativeLookup(hostname, opts, (err, ...nativeArgs) => {
+    if (!err) {
+      return callback(err, ...nativeArgs);
+    }
+
+    const family = opts.family === 6 ? 6 : 4;
+
+    log.error(
+      `lookup: failed for ${hostname}, error: ${Errors.toLogFormat(err)}. ` +
+        `Retrying with c-ares (IPv${family})`
+    );
+    const onRecords = (
+      fallbackErr: NodeJS.ErrnoException | null,
+      records: Array<string>
+    ): void => {
+      if (fallbackErr) {
+        return callback(fallbackErr, '', 0);
+      }
+
+      if (!Array.isArray(records) || records.length === 0) {
+        return callback(
+          new Error(`No DNS records returned for: ${hostname}`),
+          '',
+          0
+        );
+      }
+
+      const index = Math.floor(Math.random() * records.length);
+      callback(null, records[index], family);
+    };
+
+    if (family === 4) {
+      resolve4(hostname, onRecords);
+    } else {
+      resolve6(hostname, onRecords);
+    }
+  });
+}