skip resolving preview when a link is known to be recursive

packages/frontend/src/components/MkNote.vue

@@ -236,6 +236,7 @@ import { useRouter } from '@/router.js';
 import SkMutedNote from '@/components/SkMutedNote.vue';
 import SkNoteTranslation from '@/components/SkNoteTranslation.vue';
 import { getSelfNoteIds } from '@/utility/get-self-note-ids.js';
+import { extractPreviewUrls } from '@/utility/extract-preview-urls.js';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
@@ -303,7 +304,7 @@ const galleryEl = useTemplateRef('galleryEl');
 const isMyRenote = $i && ($i.id === note.value.userId);
 const showContent = ref(prefer.s.uncollapseCW);
 const parsed = computed(() => appearNote.value.text ? mfm.parse(appearNote.value.text) : null);
-const urls = computed(() => parsed.value ? extractUrlFromMfm(parsed.value).filter((url) => appearNote.value.renote?.url !== url && appearNote.value.renote?.uri !== url) : null);
+const urls = computed(() => parsed.value ? extractPreviewUrls(props.note, parsed.value) : null);
 const selfNoteIds = computed(() => getSelfNoteIds(props.note));
 const isLong = shouldCollapsed(appearNote.value, urls.value ?? []);
 const collapsed = ref(prefer.s.expandLongNote && appearNote.value.cw == null && isLong ? false : appearNote.value.cw == null && isLong);

packages/frontend/src/components/MkNoteDetailed.vue

@@ -286,6 +286,7 @@ import { DI } from '@/di.js';
 import SkMutedNote from '@/components/SkMutedNote.vue';
 import SkNoteTranslation from '@/components/SkNoteTranslation.vue';
 import { getSelfNoteIds } from '@/utility/get-self-note-ids.js';
+import { extractPreviewUrls } from '@/utility/extract-preview-urls.js';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
@@ -338,10 +339,10 @@ const isDeleted = ref(false);
 const renoted = ref(false);
 const translation = ref<Misskey.entities.NotesTranslateResponse | false | null>(null);
 const translating = ref(false);
-const parsed = appearNote.value.text ? mfm.parse(appearNote.value.text) : null;
+const parsed = computed(() => appearNote.value.text ? mfm.parse(appearNote.value.text) : null);
-const urls = parsed ? extractUrlFromMfm(parsed).filter((url) => appearNote.value.renote?.url !== url && appearNote.value.renote?.uri !== url) : null;
+const urls = computed(() => parsed.value ? extractPreviewUrls(props.note, parsed.value) : null);
 const selfNoteIds = computed(() => getSelfNoteIds(props.note));
-const animated = computed(() => parsed ? checkAnimationFromMfm(parsed) : null);
+const animated = computed(() => parsed.value ? checkAnimationFromMfm(parsed.value) : null);
 const allowAnim = ref(prefer.s.advancedMfm && prefer.s.animatedMfm);
 const showTicker = (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.value.user.instance);
 const conversation = ref<Misskey.entities.Note[]>([]);

packages/frontend/src/components/SkNote.vue

@@ -236,6 +236,7 @@ import { useRouter } from '@/router.js';
 import SkMutedNote from '@/components/SkMutedNote.vue';
 import SkNoteTranslation from '@/components/SkNoteTranslation.vue';
 import { getSelfNoteIds } from '@/utility/get-self-note-ids.js';
+import { extractPreviewUrls } from '@/utility/extract-preview-urls.js';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
@@ -303,7 +304,7 @@ const galleryEl = useTemplateRef('galleryEl');
 const isMyRenote = $i && ($i.id === note.value.userId);
 const showContent = ref(prefer.s.uncollapseCW);
 const parsed = computed(() => appearNote.value.text ? mfm.parse(appearNote.value.text) : null);
-const urls = computed(() => parsed.value ? extractUrlFromMfm(parsed.value).filter((url) => appearNote.value.renote?.url !== url && appearNote.value.renote?.uri !== url) : null);
+const urls = computed(() => parsed.value ? extractPreviewUrls(props.note, parsed.value) : null);
 const selfNoteIds = computed(() => getSelfNoteIds(props.note));
 const isLong = shouldCollapsed(appearNote.value, urls.value ?? []);
 const collapsed = ref(prefer.s.expandLongNote && appearNote.value.cw == null && isLong ? false : appearNote.value.cw == null && isLong);

packages/frontend/src/components/SkNoteDetailed.vue

@@ -291,6 +291,7 @@ import { DI } from '@/di.js';
 import SkMutedNote from '@/components/SkMutedNote.vue';
 import SkNoteTranslation from '@/components/SkNoteTranslation.vue';
 import { getSelfNoteIds } from '@/utility/get-self-note-ids.js';
+import { extractPreviewUrls } from '@/utility/extract-preview-urls';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
@@ -344,10 +345,10 @@ const isDeleted = ref(false);
 const renoted = ref(false);
 const translation = ref<Misskey.entities.NotesTranslateResponse | false | null>(null);
 const translating = ref(false);
-const parsed = appearNote.value.text ? mfm.parse(appearNote.value.text) : null;
+const parsed = computed(() => appearNote.value.text ? mfm.parse(appearNote.value.text) : null);
-const urls = parsed ? extractUrlFromMfm(parsed).filter((url) => appearNote.value.renote?.url !== url && appearNote.value.renote?.uri !== url) : null;
+const urls = computed(() => parsed.value ? extractPreviewUrls(props.note, parsed.value) : null);
 const selfNoteIds = computed(() => getSelfNoteIds(props.note));
-const animated = computed(() => parsed ? checkAnimationFromMfm(parsed) : null);
+const animated = computed(() => parsed.value ? checkAnimationFromMfm(parsed.value) : null);
 const allowAnim = ref(prefer.s.advancedMfm && prefer.s.animatedMfm ? true : false);
 const showTicker = (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.value.user.instance);
 const conversation = ref<Misskey.entities.Note[]>([]);

packages/frontend/src/components/SkOldNoteWindow.vue

@@ -86,7 +86,6 @@ import MkPoll from '@/components/MkPoll.vue';
 import MkUrlPreview from '@/components/MkUrlPreview.vue';
 import MkInstanceTicker from '@/components/MkInstanceTicker.vue';
 import { userPage } from '@/filters/user.js';
-import { extractUrlFromMfm } from '@/utility/extract-url-from-mfm.js';
 import { i18n } from '@/i18n.js';
 import { deepClone } from '@/utility/clone.js';
 import { dateTimeFormat } from '@/utility/intl-const.js';
@@ -94,6 +93,7 @@ import { prefer } from '@/preferences';
 import { getPluginHandlers } from '@/plugin.js';
 import SkNoteTranslation from '@/components/SkNoteTranslation.vue';
 import { getSelfNoteIds } from '@/utility/get-self-note-ids';
+import { extractPreviewUrls } from '@/utility/extract-preview-urls.js';
 
 const props = defineProps<{
 	note: Misskey.entities.Note;
@@ -142,14 +142,13 @@ const isRenote = (
 );
 
 const el = shallowRef<HTMLElement>();
-let appearNote = computed(() => isRenote ? note.value.renote as Misskey.entities.Note : note.value);
+const appearNote = computed(() => isRenote ? note.value.renote as Misskey.entities.Note : note.value);
-const renoteUrl = appearNote.value.renote ? appearNote.value.renote.url : null;
+const parsed = computed(() => appearNote.value.text ? mfm.parse(appearNote.value.text) : null);
-const renoteUri = appearNote.value.renote ? appearNote.value.renote.uri : null;
 
 const showContent = ref(false);
 const translation = ref<Misskey.entities.NotesTranslateResponse | false | null>(null);
 const translating = ref(false);
-const urls = appearNote.value.text ? extractUrlFromMfm(mfm.parse(appearNote.value.text)).filter(u => u !== renoteUrl && u !== renoteUri) : null;
+const urls = computed(() => parsed.value ? extractPreviewUrls(props.note, parsed.value) : null);
 const selfNoteIds = computed(() => getSelfNoteIds(props.note));
 const showTicker = (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.value.user.instance);
 

packages/frontend/src/utility/extract-preview-urls.ts

@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { host } from '@@/js/config.js';
+import type * as Misskey from 'misskey-js';
+import type * as mfm from '@transfem-org/sfm-js';
+import { extractUrlFromMfm } from '@/utility/extract-url-from-mfm.js';
+
+/**
+ * Extracts all previewable URLs from a note.
+ */
+export function extractPreviewUrls(note: Misskey.entities.Note, contents: mfm.MfmNode[]): string[] {
+	const links = extractUrlFromMfm(contents);
+	return links.filter(url =>
+		// Remote note
+		url !== note.url &&
+		url !== note.uri &&
+		// Local note
+		url !== `https://${host}/notes/${note.id}` &&
+		// Remote renote or quote
+		url !== note.renote?.url &&
+		url !== note.renote?.uri &&
+		// Local renote or quote
+		url !== `https://${host}/notes/${note.renote?.id}` &&
+		// Remote renote *of* a quote
+		url !== note.renote?.renote?.url &&
+		url !== note.renote?.renote?.uri &&
+		// Local renote *of* a quote
+		url !== `https://${host}/notes/${note.renote?.renote?.id}`);
+}

packages/frontend/src/utility/extract-url-from-mfm.ts

@@ -10,6 +10,7 @@ import { unique } from '@/utility/array.js';
 // [ http://a/#1, http://a/#2, http://b/#3 ] => [ http://a/#1, http://b/#3 ]
 const removeHash = (x: string) => x.replace(/#[^#]*$/, '');
 
+// TODO this is O(n^2) which could introduce a frontend DoS with a large enough character limit
 export function extractUrlFromMfm(nodes: mfm.MfmNode[], respectSilentFlag = true): string[] {
 	const urlNodes = mfm.extract(nodes, (node) => {
 		return (node.type === 'url') || (node.type === 'link' && (!respectSilentFlag || !node.props.silent));