implement fetching host-meta before the webfinger endpoint

code ported from iceshrimp: https://iceshrimp.dev/iceshrimp/iceshrimp/src/commit/c3e685a925a89b4abc19684263e87691dd9f0c6d/packages/backend/src/remote/webfinger.ts

packages/backend/package.json

@@ -112,6 +112,7 @@
 		"content-disposition": "0.5.4",
 		"date-fns": "2.30.0",
 		"deep-email-validator": "0.1.21",
+		"fast-xml-parser": "^4.4.0",
 		"fastify": "4.26.2",
 		"fastify-multer": "^2.0.3",
 		"fastify-raw-body": "4.3.0",

packages/backend/src/core/WebfingerService.ts

@@ -5,7 +5,7 @@
 
 import { URL } from 'node:url';
 import { Injectable } from '@nestjs/common';
-import { query as urlQuery } from '@/misc/prelude/url.js';
+import { XMLParser } from 'fast-xml-parser';
 import { HttpRequestService } from '@/core/HttpRequestService.js';
 import { bindThis } from '@/decorators.js';
 
@@ -31,25 +31,76 @@ export class WebfingerService {
 
 	@bindThis
 	public async webfinger(query: string): Promise<IWebFinger> {
-		const url = this.genUrl(query);
+		const hostMetaUrl = this.queryToHostMetaUrl(query);
+		const template = await this.fetchHostMeta(hostMetaUrl) ?? this.queryToWebFingerTemplate(query);
+		const url = this.genUrl(query, template);
 
 		return await this.httpRequestService.getJson<IWebFinger>(url, 'application/jrd+json, application/json');
 	}
 
 	@bindThis
-	private genUrl(query: string): string {
+	private genUrl(query: string, template: string): string {
+		if (template.indexOf('{uri}') < 0) throw new Error(`Invalid webFingerUrl: ${template}`);
+
+		if (query.match(/^https?:\/\//)) {
+			return template.replace('{uri}', encodeURIComponent(query));
+		}
+
+		const m = query.match(/^([^@]+)@(.*)/);
+		if (m) {
+			return template.replace('{uri}', encodeURIComponent(`acct:${query}`));
+		}
+
+		throw new Error(`Invalid query (${query})`);
+	}
+
+	@bindThis
+	private queryToWebFingerTemplate(query: string): string {
+		if (query.match(/^https?:\/\//)) {
+			const u = new URL(query);
+			return `${u.protocol}//${u.hostname}/.well-known/webfinger?resource={uri}`;
+		}
+
+		const m = query.match(/^([^@]+)@(.*)/);
+		if (m) {
+			const hostname = m[2];
+			return `https://${hostname}/.well-known/webfinger?resource={uri}`;
+		}
+
+		throw new Error(`Invalid query (${query})`);
+	}
+
+	@bindThis
+	private queryToHostMetaUrl(query: string): string {
 		if (query.match(urlRegex)) {
 			const u = new URL(query);
-			return `${u.protocol}//${u.hostname}/.well-known/webfinger?` + urlQuery({ resource: query });
+			return `${u.protocol}//${u.hostname}/.well-known/host-meta`;
 		}
 
 		const m = query.match(mRegex);
 		if (m) {
 			const hostname = m[2];
-			const useHttp = process.env.MISSKEY_WEBFINGER_USE_HTTP && process.env.MISSKEY_WEBFINGER_USE_HTTP.toLowerCase() === 'true';
-			return `http${useHttp ? '' : 's'}://${hostname}/.well-known/webfinger?${urlQuery({ resource: `acct:${query}` })}`;
+			return `https://${hostname}/.well-known/host-meta`;
 		}
 
 		throw new Error(`Invalid query (${query})`);
 	}
+
+	@bindThis
+	private async fetchHostMeta(url: string): Promise<string | null> {
+		try {
+			const res = await this.httpRequestService.getHtml(url, 'application/xrd+xml');
+			const options = {
+				ignoreAttributes: false,
+				isArray: (_name: string, jpath: string) => jpath === 'XRD.Link',
+			};
+			const parser = new XMLParser(options);
+			const hostMeta = parser.parse(res);
+			const template = (hostMeta['XRD']['Link'] as Array<any>).filter(p => p['@_rel'] === 'lrdd')[0]['@_template'];
+			return template.indexOf('{uri}') < 0 ? null : template;
+		} catch (err) {
+			console.error(`error while request host-meta for ${url}`);
+			return null;
+		}
+	}
 }

pnpm-lock.yaml

@@ -220,6 +220,9 @@ importers:
       deep-email-validator:
         specifier: 0.1.21
         version: 0.1.21
+      fast-xml-parser:
+        specifier: ^4.4.0
+        version: 4.4.0
       fastify:
         specifier: 4.26.2
         version: 4.26.2
@@ -6821,6 +6824,10 @@ packages:
     resolution: {integrity: sha512-B9/wizE4WngqQftFPmdaMYlXoJlJOYxGQOanC77fq9k8+Z0v5dDSVh+3glErdIROP//s/jgb7ZuxKfB8nVyo0g==}
     hasBin: true
+  fast-xml-parser@4.4.0:
+    resolution: {integrity: sha512-kLY3jFlwIYwBNDojclKsNAC12sfD6NwW74QB2CoNGPvtVxjliYehVunB3HYyNi+n4Tt1dAcgwYvmKF/Z18flqg==}
+    hasBin: true
+
   fastify-multer@2.0.3:
     resolution: {integrity: sha512-QnFqrRgxmUwWHTgX9uyQSu0C/hmVCfcxopqjApZ4uaZD5W9MJ+nHUlW4+9q7Yd3BRxDIuHvgiM5mjrh6XG8cAA==}
     engines: {node: '>=10.17.0'}
@@ -11105,8 +11112,8 @@ packages:
   vue-component-type-helpers@2.0.16:
     resolution: {integrity: sha512-qisL/iAfdO++7w+SsfYQJVPj6QKvxp4i1MMxvsNO41z/8zu3KuAw9LkhKUfP/kcOWGDxESp+pQObWppXusejCA==}
-  vue-component-type-helpers@2.0.19:
-    resolution: {integrity: sha512-cN3f1aTxxKo4lzNeQAkVopswuImUrb5Iurll9Gaw5cqpnbTAxtEMM1mgi6ou4X79OCyqYv1U1mzBHJkzmiK82w==}
+  vue-component-type-helpers@2.0.26:
+    resolution: {integrity: sha512-sO9qQ8oC520SW6kqlls0iqDak53gsTVSrYylajgjmkt1c0vcgjsGSy1KzlDrbEx8pm02IEYhlUkU5hCYf8rwtg==}
   vue-demi@0.14.7:
     resolution: {integrity: sha512-EOG8KXDQNwkJILkx/gPcoL/7vH+hORoBaKgGe+6W7VFMvCYJfmF2dGbvgDroVnI8LU7/kTu8mbjRZGBU1z9NTA==}
@@ -15449,7 +15456,7 @@ snapshots:
       ts-dedent: 2.2.0
       type-fest: 2.19.0
       vue: 3.4.26(typescript@5.4.5)
-      vue-component-type-helpers: 2.0.19
+      vue-component-type-helpers: 2.0.26
     transitivePeerDependencies:
       - encoding
       - supports-color
@@ -18827,6 +18834,10 @@ snapshots:
     dependencies:
       strnum: 1.0.5
+  fast-xml-parser@4.4.0:
+    dependencies:
+      strnum: 1.0.5
+
   fastify-multer@2.0.3:
     dependencies:
       '@fastify/busboy': 1.2.1
@@ -19708,7 +19719,7 @@ snapshots:
   is-svg@5.0.0:
     dependencies:
-      fast-xml-parser: 4.2.5
+      fast-xml-parser: 4.4.0
   is-symbol@1.0.4:
     dependencies:
@@ -23644,7 +23655,7 @@ snapshots:
   vue-component-type-helpers@2.0.16: {}
-  vue-component-type-helpers@2.0.19: {}
+  vue-component-type-helpers@2.0.26: {}
   vue-demi@0.14.7(vue@3.4.26(typescript@5.4.5)):
     dependencies: