Added custom webfinger handler

src/app.ts

@@ -115,6 +115,7 @@ import {
     handleWebhookSiteChanged,
 } from './http/api';
 import { AccountFollowsView } from './http/api/views/account.follows.view';
+import { createWebFingerHandler } from './http/handler/webfinger';
 import { spanWrapper } from './instrumentation';
 import { KnexKvStore } from './knex.kvstore';
 import { scopeKvStore } from './kv-helpers';
@@ -247,7 +248,7 @@ if (process.env.MANUALLY_START_QUEUE === 'true') {
     });
 }
 
-const flagService = new FlagService([]);
+const flagService = new FlagService(['custom-webfinger']);
 
 const events = new AsyncEvents();
 const fedifyContextFactory = new FedifyContextFactory();
@@ -902,6 +903,13 @@ function requireRole(...roles: GhostRole[]) {
     };
 }
 
+app.get(
+    '/.well-known/webfinger',
+    spanWrapper(
+        createWebFingerHandler(accountRepository, siteService, flagService),
+    ),
+);
+
 app.get(
     '/.ghost/activitypub/inbox/:handle',
     requireRole(GhostRole.Owner, GhostRole.Administrator),

src/flag/flag.service.ts

@@ -41,6 +41,10 @@ export class FlagService {
         return store.has(flag);
     }
 
+    public isDisabled(flag: string) {
+        return !this.isEnabled(flag);
+    }
+
     public getRegistered() {
         return Array.from(this.flags);
     }

src/flag/flag.service.unit.test.ts

@@ -58,4 +58,17 @@ describe('FlagService', () => {
             expect(flagService.isEnabled('bar')).toBe(true);
         });
     });
+
+    it('should be able to check if a flag is disabled', () => {
+        const flagService = new FlagService(['foo', 'bar']);
+
+        flagService.runInContext(async () => {
+            expect(flagService.isDisabled('foo')).toBe(true); // registered but not enabled
+
+            expect(flagService.isDisabled('baz')).toBe(true); // not registered
+
+            flagService.enable('bar');
+            expect(flagService.isDisabled('bar')).toBe(false);
+        });
+    });
 });

src/http/handler/webfinger.ts

@@ -0,0 +1,88 @@
+import type { Context as HonoContext, Next } from 'hono';
+
+import type { Account } from 'account/account.entity';
+import type { KnexAccountRepository } from 'account/account.repository.knex';
+import type { FlagService } from 'flag/flag.service';
+import type { SiteService } from 'site/site.service';
+
+const ACCOUNT_RESOURCE_PREFIX = 'acct:';
+const HOST_REGEX = /^([a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.[a-zA-Z0-9]+)$/;
+
+export function createWebFingerHandler(
+    accountRepository: KnexAccountRepository,
+    siteService: SiteService,
+    flagService: FlagService,
+) {
+    /**
+     * Custom webfinger implementation to allow resources hosted on the www
+     * version of a host to resolve to the non-www version of the host
+     *
+     * @see https://github.com/fedify-dev/fedify/blob/main/src/webfinger/handler.ts
+     */
+    return async function handleWebFinger(ctx: HonoContext, next: Next) {
+        if (flagService.isDisabled('custom-webfinger')) {
+            return next();
+        }
+
+        const resource = ctx.req.query('resource');
+
+        // We only support custom handling of `acct:` resources - If the
+        // resource is not an `acct:` resource, fallback to the default
+        // webfinger implementation
+        if (!resource || !resource.startsWith(ACCOUNT_RESOURCE_PREFIX)) {
+            return next();
+        }
+
+        const [_, resourceHost] = resource
+            .slice(ACCOUNT_RESOURCE_PREFIX.length)
+            .split('@');
+        if (!resourceHost || !HOST_REGEX.test(resourceHost)) {
+            return new Response(null, {
+                status: 400,
+            });
+        }
+
+        const site =
+            (await siteService.getSiteByHost(resourceHost)) ||
+            (await siteService.getSiteByHost(`www.${resourceHost}`));
+
+        if (!site) {
+            return new Response(null, {
+                status: 404,
+            });
+        }
+
+        let account: Account;
+
+        try {
+            account = await accountRepository.getBySite(site);
+        } catch (error) {
+            return new Response(null, {
+                status: 404,
+            });
+        }
+
+        const webfingerData = {
+            subject: `acct:${account.username}@${site.host.replace('www.', '')}`,
+            aliases: [account.apId.toString()],
+            links: [
+                {
+                    rel: 'self',
+                    href: account.apId.toString(),
+                    type: 'application/activity+json',
+                },
+                {
+                    rel: 'http://webfinger.net/rel/profile-page',
+                    href: account.url.toString(),
+                },
+            ],
+        };
+
+        return new Response(JSON.stringify(webfingerData), {
+            status: 200,
+            headers: {
+                'Content-Type': 'application/jrd+json',
+            },
+        });
+    };
+}