Implement Webfinger

src/app.ts

@@ -28,6 +28,7 @@ import {
 import { streamingController } from './controllers/api/streaming.ts';
 import { indexController } from './controllers/site.ts';
 import { nostrController } from './controllers/well-known/nostr.ts';
+import { hostMetaController, webfingerController } from './controllers/well-known/webfinger.ts';
 import { auth19, requireAuth } from './middleware/auth19.ts';
 import { auth98 } from './middleware/auth98.ts';
 
@@ -57,6 +58,8 @@ app.get('/api/v1/streaming/', streamingController);
 
 app.use('*', cors({ origin: '*', exposeHeaders: ['link'] }), auth19, auth98());
 
+app.get('/.well-known/webfinger', webfingerController);
+app.get('/.well-known/host-meta', hostMetaController);
 app.get('/.well-known/nostr.json', nostrController);
 
 app.get('/api/v1/instance', instanceController);

src/controllers/well-known/nostr.ts

@@ -1,8 +1,8 @@
+import { Conf } from '@/config.ts';
 import { db } from '@/db.ts';
 import { z } from '@/deps.ts';
 
 import type { AppController } from '@/app.ts';
-import { Conf } from '../../config.ts';
 
 const nameSchema = z.string().min(1).regex(/^\w+$/);
 

src/controllers/well-known/webfinger.ts

@@ -0,0 +1,75 @@
+import { Conf } from '@/config.ts';
+import { db } from '@/db.ts';
+import { nip19, z } from '@/deps.ts';
+import { urlTransformSchema } from '@/schema.ts';
+
+import type { AppController } from '@/app.ts';
+import type { Webfinger } from '@/schemas/webfinger.ts';
+
+const webfingerController: AppController = async (c) => {
+  const { hostname } = new URL(Conf.localDomain);
+
+  /** Transforms the resource URI into a `[username, domain]` tuple. */
+  const acctSchema = urlTransformSchema
+    .refine((uri) => uri.protocol === 'acct:', 'Protocol must be `acct:`')
+    .refine((uri) => z.string().email().safeParse(uri.pathname).success, 'Invalid acct')
+    .transform((uri) => uri.pathname.split('@') as [username: string, host: string])
+    .refine(([_username, host]) => host === hostname, 'Host must be local');
+
+  const result = acctSchema.safeParse(c.req.query('resource'));
+  if (!result.success) {
+    return c.json({ error: 'Bad request', schema: result.error }, 400);
+  }
+
+  try {
+    const user = await db.users.findFirst({ where: { username: result.data[0] } });
+    c.header('content-type', 'application/jrd+json');
+    return c.body(JSON.stringify(renderWebfinger(user)));
+  } catch (_e) {
+    return c.json({ error: 'Not found' }, 404);
+  }
+};
+
+const hostMetaController: AppController = (c) => {
+  const template = Conf.url('/.well-known/webfinger?resource={uri}');
+
+  c.header('content-type', 'application/xrd+xml');
+  return c.body(
+    `<?xml version="1.0" encoding="UTF-8"?><XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0"><Link rel="lrdd" template="${template}" type="application/xrd+xml" /></XRD>`,
+  );
+};
+
+interface RenderWebfingerOpts {
+  pubkey: string;
+  username: string;
+}
+
+/** Present Nostr user on Webfinger. */
+function renderWebfinger({ pubkey, username }: RenderWebfingerOpts): Webfinger {
+  const { host } = new URL(Conf.localDomain);
+  const apId = Conf.url(`/users/${username}`);
+
+  return {
+    subject: `acct:${username}@${host}`,
+    aliases: [apId],
+    links: [
+      {
+        rel: 'self',
+        type: 'application/activity+json',
+        href: apId,
+      },
+      {
+        rel: 'self',
+        type: 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"',
+        href: apId,
+      },
+      {
+        rel: 'self',
+        type: 'application/nostr+json',
+        href: `nostr:${nip19.npubEncode(pubkey)}`,
+      },
+    ],
+  };
+}
+
+export { hostMetaController, webfingerController };

src/schema.ts

@@ -95,6 +95,20 @@ const decode64Schema = z.string().transform((value, ctx) => {
   }
 });
 
+/** Transforms a string into a `URL` object. */
+const urlTransformSchema = z.string().transform((val, ctx) => {
+  try {
+    return new URL(val);
+  } catch (_e) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Invalid URI',
+      fatal: true,
+    });
+    return z.NEVER;
+  }
+});
+
 export {
   decode64Schema,
   emojiTagSchema,
@@ -106,4 +120,5 @@ export {
   parseRelay,
   relaySchema,
   signedEventSchema,
+  urlTransformSchema,
 };

src/schemas/webfinger.ts

@@ -0,0 +1,19 @@
+import { z } from '@/deps.ts';
+
+const linkSchema = z.object({
+  rel: z.string().optional(),
+  type: z.string().optional(),
+  href: z.string().optional(),
+  template: z.string().optional(),
+});
+
+const webfingerSchema = z.object({
+  subject: z.string(),
+  aliases: z.array(z.string()).catch([]),
+  links: z.array(linkSchema),
+});
+
+type Webfinger = z.infer<typeof webfingerSchema>;
+
+export { webfingerSchema };
+export type { Webfinger };