Make WebFinger respect host-meta

.pnp.cjs

@@ -3274,7 +3274,7 @@ function $$SETUP_STATE(hydrateRuntimeState, basePath) {
       ],\
       [\
         "fast-xml-parser",\
-        "npm:3.21.1"\
+        "npm:4.2.7"\
       ],\
       [\
         "fastest-levenshtein",\
@@ -15259,6 +15259,7 @@ function $$SETUP_STATE(hydrateRuntimeState, basePath) {
             ["escape-regexp", "npm:0.0.1"],\
             ["eslint", "npm:8.45.0"],\
             ["execa", "npm:6.1.0"],\
+            ["fast-xml-parser", "npm:4.2.7"],\
             ["feed", "npm:4.2.2"],\
             ["file-type", "npm:17.1.6"],\
             ["fluent-ffmpeg", "npm:2.1.2"],\
@@ -20798,6 +20799,14 @@ function $$SETUP_STATE(hydrateRuntimeState, basePath) {
             ["strnum", "npm:1.0.5"]\
           ],\
           "linkType": "HARD"\
+        }],\
+        ["npm:4.2.7", {\
+          "packageLocation": "./.yarn/cache/fast-xml-parser-npm-4.2.7-c57a954c1f-d8b0c9e047.zip/node_modules/fast-xml-parser/",\
+          "packageDependencies": [\
+            ["fast-xml-parser", "npm:4.2.7"],\
+            ["strnum", "npm:1.0.5"]\
+          ],\
+          "linkType": "HARD"\
         }]\
       ]],\
       ["fastest-levenshtein", [\

packages/backend/package.json

@@ -64,6 +64,7 @@
 		"decompress": "^4.2.1",
 		"deep-email-validator": "0.1.21",
 		"escape-regexp": "0.0.1",
+		"fast-xml-parser": "^4.2.7",
 		"feed": "4.2.2",
 		"file-type": "17.1.6",
 		"fluent-ffmpeg": "2.1.2",

packages/backend/src/remote/webfinger.ts

@@ -1,6 +1,8 @@
 import { URL } from "node:url";
-import { getJson } from "@/misc/fetch.js";
+import {getJson, getResponse} from "@/misc/fetch.js";
 import { query as urlQuery } from "@/prelude/url.js";
+import config from "@/config/index.js";
+import { XMLParser } from "fast-xml-parser";
 
 type ILink = {
 	href: string;
@@ -13,7 +15,9 @@ type IWebFinger = {
 };
 
 export default async function (query: string): Promise<IWebFinger> {
-	const url = genUrl(query);
+	const hostMetaUrl = queryToHostMetaUrl(query);
+	const webFingerTemplate = await hostMetaToWebFingerTemplate(hostMetaUrl) ?? queryToWebFingerTemplate(query);
+	const url = genWebFingerUrl(query, webFingerTemplate);
 
 	return (await getJson(
 		url,
@@ -21,20 +25,71 @@ export default async function (query: string): Promise<IWebFinger> {
 	)) as IWebFinger;
 }
 
-function genUrl(query: string) {
+async function hostMetaToWebFingerTemplate(url: string) {
+	try {
+		const res = await getResponse({
+			url,
+			method: "GET",
+			headers: Object.assign(
+				{
+					"User-Agent": config.userAgent,
+					Accept: "application/xml, text/xml, */*",
+				},
+				{},
+			),
+			timeout: 10000,
+		});
+		const parser = new XMLParser({ignoreAttributes: false});
+		const hostMeta = parser.parse(await res.text());
+		const template = hostMeta['XRD']['Link']['@_template'];
+		return template.indexOf('{uri}') < 0 ? null : template;
+	}
+	catch {
+		return null;
+	}
+}
+
+function queryToWebFingerTemplate(query: string) {
 	if (query.match(/^https?:\/\//)) {
 		const u = new URL(query);
-		return `${u.protocol}//${u.hostname}/.well-known/webfinger?${urlQuery({
-			resource: query,
-		})}`;
+		return `${u.protocol}//${u.hostname}/.well-known/webfinger?resource={uri}`;
 	}
 
 	const m = query.match(/^([^@]+)@(.*)/);
 	if (m) {
 		const hostname = m[2];
-		return `https://${hostname}/.well-known/webfinger?${urlQuery({
-			resource: `acct:${query}`,
-		})}`;
+		return `https://${hostname}/.well-known/webfinger?resource={uri}`;
+	}
+
+	throw new Error(`Invalid query (${query})`);
+}
+
+function queryToHostMetaUrl(query: string) {
+	if (query.match(/^https?:\/\//)) {
+		const u = new URL(query);
+		return `${u.protocol}//${u.hostname}/.well-known/host-meta`;
+	}
+
+	const m = query.match(/^([^@]+)@(.*)/);
+	if (m) {
+		const hostname = m[2];
+		return `https://${hostname}/.well-known/host-meta`;
+	}
+
+	throw new Error(`Invalid query (${query})`);
+}
+
+function genWebFingerUrl(query: string, webFingerTemplate: string) {
+	if (webFingerTemplate.indexOf('{uri}') < 0)
+		throw new Error(`Invalid webFingerUrl: ${webFingerTemplate}`);
+
+	if (query.match(/^https?:\/\//)) {
+		return webFingerTemplate.replace('{uri}', encodeURIComponent(query));
+	}
+
+	const m = query.match(/^([^@]+)@(.*)/);
+	if (m) {
+		return webFingerTemplate.replace('{uri}', encodeURIComponent(`acct:${query}`));
 	}
 
 	throw new Error(`Invalid query (${query})`);

yarn.lock

@@ -5917,6 +5917,7 @@ __metadata:
     escape-regexp: 0.0.1
     eslint: ^8.44.0
     execa: 6.1.0
+    fast-xml-parser: ^4.2.7
     feed: 4.2.2
     file-type: 17.1.6
     fluent-ffmpeg: 2.1.2
@@ -10363,6 +10364,17 @@ __metadata:
   languageName: node
   linkType: hard
 
+"fast-xml-parser@npm:^4.2.7":
+  version: 4.2.7
+  resolution: "fast-xml-parser@npm:4.2.7"
+  dependencies:
+    strnum: ^1.0.5
+  bin:
+    fxparser: src/cli/cli.js
+  checksum: d8b0c9e04756f6c43fa0399428f30149acadae21350e42e26e8fe98e24e6afa6b9b00aa554453795036b00e9fee974a1b556fe2ba18be391d51a9bf1ab790e7c
+  languageName: node
+  linkType: hard
+
 "fastest-levenshtein@npm:^1.0.12":
   version: 1.0.16
   resolution: "fastest-levenshtein@npm:1.0.16"
@@ -20888,7 +20900,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"strnum@npm:^1.0.4":
+"strnum@npm:^1.0.4, strnum@npm:^1.0.5":
   version: 1.0.5
   resolution: "strnum@npm:1.0.5"
   checksum: 651b2031db5da1bf4a77fdd2f116a8ac8055157c5420f5569f64879133825915ad461513e7202a16d7fec63c54fd822410d0962f8ca12385c4334891b9ae6dd2