server: parse quote tag syntax

Ref: FEP-e232

packages/backend/src/remote/activitypub/models/note.ts

@@ -24,7 +24,7 @@ import { DbResolver } from '../db-resolver.js';
 import { apLogger } from '../logger.js';
 import { resolvePerson } from './person.js';
 import { resolveImage } from './image.js';
-import { extractApHashtags } from './tag.js';
+import { extractApHashtags, extractQuoteUrl } from './tag.js';
 import { extractPollFromQuestion } from './question.js';
 import { extractApMentions } from './mention.js';
 
@@ -154,10 +154,10 @@ export async function createNote(value: string | IObject, resolver: Resolver, si
 		})
 		: null;
 
-	// 引用
 	let quote: Note | undefined | null;
+	const quoteUrl = extractQuoteUrl(note.tag);
 
-	if (note._misskey_quote || note.quoteUri) {
+	if (quoteUrl || note._misskey_quote || note.quoteUri) {
 		const tryResolveNote = async (uri: string): Promise<{
 			status: 'ok';
 			res: Note | null;
@@ -184,10 +184,16 @@ export async function createNote(value: string | IObject, resolver: Resolver, si
 			}
 		};
 
-		const uris = unique([note._misskey_quote, note.quoteUri].filter((x): x is string => typeof x === 'string'));
-		const results = await Promise.all(uris.map(uri => tryResolveNote(uri)));
-
-		quote = results.filter((x): x is { status: 'ok', res: Note | null } => x.status === 'ok').map(x => x.res).find(x => x);
+		const uris = unique([quoteUrl, note._misskey_quote, note.quoteUri].filter((x): x is string => typeof x === 'string'));
+		// check the urls sequentially and abort early to not do unnecessary HTTP requests
+		// picks the first one that works
+		for (const uri in uris) {
+			const res = await tryResolveNote(uri);
+			if (res.status === 'ok') {
+				quote = res.res;
+				break;
+			}
+		}
 		if (!quote) {
 			if (results.some(x => x.status === 'temperror')) {
 				throw new Error('quote resolve failed');

packages/backend/src/remote/activitypub/models/tag.ts

@@ -1,5 +1,5 @@
 import { toArray } from '@/prelude/array.js';
-import { IObject, isHashtag, IApHashtag } from '../type.js';
+import { IObject, isHashtag, IApHashtag, isLink, ILink } from '../type.js';
 
 export function extractApHashtags(tags: IObject | IObject[] | null | undefined) {
 	if (tags == null) return [];
@@ -16,3 +16,39 @@ export function extractApHashtagObjects(tags: IObject | IObject[] | null | undef
 	if (tags == null) return [];
 	return toArray(tags).filter(isHashtag);
 }
+
+// implements FEP-e232: Object Links (2022-12-23 version)
+export function extractQuoteUrl(tags: IObject | IObject[] | null | undefined): string | null {
+	if (tags == null) return null;
+
+	// filter out correct links
+	let quotes: ILink[] = toArray(tags)
+		.filter(isLink)
+		.filter(link =>
+			[
+				'application/ld+json; profile="https://www.w3.org/ns/activitystreams"',
+				'application/activity+json'
+			].includes(link.mediaType?.toLowerCase())
+		);
+
+	// sort quotes with the right rel first
+	function hasRel(link: ILink): boolean {
+		link.rel != null
+		&&
+		toArray(link.rel)
+			.includes('https://misskey-hub.net/ns#_misskey_quote')
+	}
+	quotes.sort((a, b) => {
+		return hasRel(b) - hasRel(a);
+	});
+
+	// deduplicate by href
+	quotes = quotes.filter((x, i, arr) => arr.findIndex(y => x.href === y.href) === i);
+
+	if (quotes.length === 0) return null;
+
+	// If there is more than one quote, we just pick the first/a random one.
+	// Note that links with the correct `rel` were sorted to the front above
+	// so they will be preferred.
+	return quotes[0];
+}

packages/backend/src/remote/activitypub/type.ts

@@ -279,6 +279,13 @@ export interface IFlag extends IActivity {
 	type: 'Flag';
 }
 
+export interface ILink extends IObject {
+	type: 'Link';
+	href: string;
+	rel?: string | string[];
+	mediaType?: string;
+}
+
 export const isCreate = (object: IObject): object is ICreate => getApType(object) === 'Create';
 export const isDelete = (object: IObject): object is IDelete => getApType(object) === 'Delete';
 export const isUpdate = (object: IObject): object is IUpdate => getApType(object) === 'Update';
@@ -293,3 +300,11 @@ export const isLike = (object: IObject): object is ILike => getApType(object) ==
 export const isAnnounce = (object: IObject): object is IAnnounce => getApType(object) === 'Announce';
 export const isBlock = (object: IObject): object is IBlock => getApType(object) === 'Block';
 export const isFlag = (object: IObject): object is IFlag => getApType(object) === 'Flag';
+export const isLink = (object: IObject): object is ILink => getApType(object) === 'Link'
+	&& typeof object.href === 'string'
+	&& (
+		object.rel == undefined
+		|| typeof object.rel === 'string'
+		|| (Array.isArray(object.rel) && object.rel.every(x => typeof x === 'string'))
+	)
+	&& (object.mediaType == undefined || typeof object.mediaType === 'string');