Fix: IPv4 onlyホストからDualstackホストにAP deliverできない (#4879)

.config/example.yml

@@ -113,3 +113,6 @@ autoAdmin: true
 
 # Clustering
 #clusterLimit: 1
+
+# IP address family used for outgoing request (ipv4, ipv6 or dual)
+#outgoingAddressFamily: ipv4

src/config/types.ts

@@ -42,6 +42,8 @@ export type Source = {
 	accesslog?: string;
 
 	clusterLimit?: number;
+
+	outgoingAddressFamily?: 'ipv4' | 'ipv6' | 'dual';
 };
 
 /**

src/remote/activitypub/request.ts

@@ -96,11 +96,18 @@ export default async (user: ILocalUser, url: string, object: any) => {
  * Resolve host (with cached, asynchrony)
  */
 async function resolveAddr(domain: string) {
+	const af = config.outgoingAddressFamily || 'ipv4';
+	const useV4 = af == 'ipv4' || af == 'dual';
+	const useV6 = af == 'ipv6' || af == 'dual';
+
+	const promises = [];
+
+	if (!useV4 && !useV6) throw 'No usable address family available';
+	if (useV4) promises.push(resolveAddrInner(domain, { family: 4 }));
+	if (useV6) promises.push(resolveAddrInner(domain, { family: 6 }));
+
 	// v4/v6で先に取得できた方を採用する
-	return await promiseAny([
-		resolveAddrInner(domain, { family: 4 }),
-		resolveAddrInner(domain, { family: 6 })
-	]);
+	return await promiseAny(promises);
 }
 
 function resolveAddrInner(domain: string, options: IRunOptions = {}): Promise<string> {