activitypub: hashtags no longer displaying as links

Some hashtags sent from Mastodon were erroneously displayed as links.
This is because Mastodon seems to mangle hashtags containing non-ASCII
codepoints (such as e.g. umlauts). This lead to the previous code which
depended on the list of hashtags to not recognize a hashtag. Instead,
the `rel="tag"` microformat is recognized instead.

This makes the `htmlToMfm` wrapper function unnecessary so it was removed.

Changelog: Fixed

packages/backend/src/mfm/from-html.ts

@@ -7,7 +7,7 @@ const treeAdapter = parse5.defaultTreeAdapter;
 const urlRegex = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+/;
 const urlRegexFull = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+$/;
 
-export function fromHtml(html: string, hashtagNames?: string[], quoteUri?: string | null): string {
+export function fromHtml(html: string, quoteUri?: string | null): string {
 	const dom = parse5.parseFragment(
 		// some AP servers like Pixelfed use br tags as well as newlines
 		html.replace(/<br\s?\/?>\r?\n/gi, '\n'),
@@ -63,7 +63,7 @@ export function fromHtml(html: string, hashtagNames?: string[], quoteUri?: strin
 				const href = node.attrs.find(x => x.name === 'href');
 
 				// hashtags
-				if (hashtagNames && href && hashtagNames.map(x => x.toLowerCase()).includes(txt.toLowerCase())) {
+				if (txt.startsWith('#') && href && /\btag\b/.test(rel?.value)) {
 					text += txt;
 				// mentions
 				} else if (txt.startsWith('@') && !(rel && rel.value.match(/^me /))) {

packages/backend/src/remote/activitypub/misc/html-to-mfm.ts

@@ -1,9 +0,0 @@
-import { IObject } from '../type.js';
-import { extractApHashtagObjects } from '../models/tag.js';
-import { fromHtml } from '@/mfm/from-html.js';
-
-export function htmlToMfm(html: string, tag?: IObject | IObject[], quoteUri?: string | null) {
-	const hashtagNames = extractApHashtagObjects(tag).map(x => x.name).filter((x): x is string => x != null);
-
-	return fromHtml(html, hashtagNames, quoteUri);
-}

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

@@ -16,11 +16,11 @@ import { fetchMeta } from '@/misc/fetch-meta.js';
 import { getApLock } from '@/misc/app-lock.js';
 import { createMessage } from '@/services/messages/create.js';
 import { StatusError } from '@/misc/fetch.js';
+import { fromHtml } from '@/mfm/from-html.js';
 import { parseAudience } from '../audience.js';
 import { IObject, getOneApId, getApId, getOneApHrefNullable, validPost, IPost, isEmoji, getApType } from '../type.js';
 import DbResolver from '../db-resolver.js';
 import Resolver from '../resolver.js';
-import { htmlToMfm } from '../misc/html-to-mfm.js';
 import { apLogger } from '../logger.js';
 import { resolvePerson } from './person.js';
 import { resolveImage } from './image.js';
@@ -199,7 +199,7 @@ export async function createNote(value: string | IObject, resolver?: Resolver =
 	} else if (typeof note._misskey_content !== 'undefined') {
 		text = note._misskey_content;
 	} else if (typeof note.content === 'string') {
-		text = htmlToMfm(note.content, note.tag, quote?.uri);
+		text = fromHtml(note.content, quote?.uri);
 	}
 
 	// vote

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

@@ -24,7 +24,6 @@ import { uriPersonCache } from '@/services/user-cache.js';
 import { publishInternalEvent } from '@/services/stream.js';
 import { db } from '@/db/postgre.js';
 import { apLogger } from '../logger.js';
-import { htmlToMfm } from '../misc/html-to-mfm.js';
 import { fromHtml } from '@/mfm/from-html.js';
 import { isCollectionOrOrderedCollection, isCollection, IActor, getApId, getOneApHrefNullable, IObject, isPropertyValue, IApPropertyValue, getApType, isActor } from '../type.js';
 import Resolver from '../resolver.js';
@@ -185,7 +184,7 @@ export async function createPerson(uri: string, resolver?: Resolver = new Resolv
 
 			await transactionalEntityManager.save(new UserProfile({
 				userId: user.id,
-				description: person.summary ? htmlToMfm(truncate(person.summary, summaryLength), person.tag) : null,
+				description: person.summary ? fromHtml(truncate(person.summary, summaryLength)) : null,
 				url: getOneApHrefNullable(person.url),
 				fields,
 				birthday: bday ? bday[0] : null,
@@ -361,7 +360,7 @@ export async function updatePerson(uri: string, resolver?: Resolver = new Resolv
 	await UserProfiles.update({ userId: exist.id }, {
 		url: getOneApHrefNullable(person.url),
 		fields,
-		description: person.summary ? htmlToMfm(truncate(person.summary, summaryLength), person.tag) : null,
+		description: person.summary ? fromHtml(truncate(person.summary, summaryLength)) : null,
 		birthday: bday ? bday[0] : null,
 		location: person['vcard:Address'] || null,
 	});