fix: also recognize "shortcut icon" favicon (#8220)

* also recognize "shortcut icon" favicon

Not using querySelector for this because it uses jsdom which might be slower.
Reversing the order because WHATWG says the last appropriate link should be used.

* also fetchIconUrl

* br

* improve readability

* fix

* フォールバックにhrefの評価を含める

* fix val name

* 将来的な拡張を考えたコードにした

Co-authored-by: tamaina <tamaina@hotmail.co.jp>
Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/backend/src/services/fetch-instance-metadata.ts

@@ -156,7 +156,8 @@ async function fetchFaviconUrl(instance: Instance, doc: DOMWindow['document'] |
 	const url = 'https://' + instance.host;
 
 	if (doc) {
-		const href = doc.querySelector('link[rel="icon"]')?.getAttribute('href');
+		// https://github.com/misskey-dev/misskey/pull/8220#issuecomment-1025104043
+		const href = Array.from(doc.getElementsByTagName('link')).reverse().find(link => link.relList.contains('icon'))?.href;
 
 		if (href) {
 			return (new URL(href, url)).href;
@@ -186,11 +187,16 @@ async function fetchIconUrl(instance: Instance, doc: DOMWindow['document'] | nul
 	if (doc) {
 		const url = 'https://' + instance.host;
 
-		const hrefAppleTouchIconPrecomposed = doc.querySelector('link[rel="apple-touch-icon-precomposed"]')?.getAttribute('href');
-		const hrefAppleTouchIcon = doc.querySelector('link[rel="apple-touch-icon"]')?.getAttribute('href');
-		const hrefIcon = doc.querySelector('link[rel="icon"]')?.getAttribute('href');
-
-		const href = hrefAppleTouchIconPrecomposed || hrefAppleTouchIcon || hrefIcon;
+		// https://github.com/misskey-dev/misskey/pull/8220#issuecomment-1025104043
+		const links = Array.from(doc.getElementsByTagName('link')).reverse();
+		// https://github.com/misskey-dev/misskey/pull/8220/files/0ec4eba22a914e31b86874f12448f88b3e58dd5a#r796487559
+		const href = 
+			[
+				links.find(link => link.relList.contains('apple-touch-icon-precomposed'))?.href,
+				links.find(link => link.relList.contains('apple-touch-icon'))?.href,
+				links.find(link => link.relList.contains('icon'))?.href,
+			]
+			.find(href => href);
 
 		if (href) {
 			return (new URL(href, url)).href;