From bbda7485f6439938d5f5933f5a07fd09a922be18 Mon Sep 17 00:00:00 2001
From: benjdlambert <ben@blam.sh>
Date: Thu, 3 Jul 2025 10:24:53 +0200
Subject: [PATCH] feat: adding client register Signed-off-by: benjdlambert
 <ben@blam.sh>

Signed-off-by: benjdlambert <ben@blam.sh>
---
 .../src/service/OidcRouter.test.ts            |  2 ++
 .../auth-backend/src/service/OidcRouter.ts    | 28 ++++++++++++++++++-
 .../auth-backend/src/service/OidcService.ts   | 28 +++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/plugins/auth-backend/src/service/OidcRouter.test.ts b/plugins/auth-backend/src/service/OidcRouter.test.ts
index dbc6c88f93..8e53abbcaf 100644
--- a/plugins/auth-backend/src/service/OidcRouter.test.ts
+++ b/plugins/auth-backend/src/service/OidcRouter.test.ts
@@ -37,6 +37,8 @@ describe('OidcRouter', () => {
         }),
       } as unknown as UserInfoDatabase;
 
+      const mockOidc = {};
+
       const { server } = await startTestBackend({
         features: [
           createBackendPlugin({
diff --git a/plugins/auth-backend/src/service/OidcRouter.ts b/plugins/auth-backend/src/service/OidcRouter.ts
index 6ada071c44..219e026a53 100644
--- a/plugins/auth-backend/src/service/OidcRouter.ts
+++ b/plugins/auth-backend/src/service/OidcRouter.ts
@@ -15,10 +15,12 @@
  */
 import Router from 'express-promise-router';
 import { OidcService } from './OidcService';
-import { AuthenticationError } from '@backstage/errors';
+import { AuthenticationError, isError } from '@backstage/errors';
 import { AuthService } from '@backstage/backend-plugin-api';
 import { TokenIssuer } from '../identity/types';
 import { UserInfoDatabase } from '../database/UserInfoDatabase';
+import { rest } from 'lodash';
+import { OidcDatabase } from '../database/OidcDatabase';
 
 export class OidcRouter {
   private constructor(private readonly oidc: OidcService) {}
@@ -28,6 +30,7 @@ export class OidcRouter {
     tokenIssuer: TokenIssuer;
     baseUrl: string;
     userInfo: UserInfoDatabase;
+    oidc: OidcDatabase;
   }) {
     return new OidcRouter(OidcService.create(options));
   }
@@ -68,6 +71,29 @@ export class OidcRouter {
       res.json(userInfo);
     });
 
+    router.get('/v1/register', async (req, res) => {
+      // todo(blam): maybe add zod types for validating input
+      const registrationRequest = req.body;
+      if (!registrationRequest.redirect_uris?.length) {
+        res.status(400).json({
+          error: 'invalid_request',
+          error_description: 'redirect_uris is required',
+        });
+        return;
+      }
+
+      try {
+        res.json(await this.oidc.registerClient(registrationRequest));
+      } catch (e) {
+        res.status(500).json({
+          error: 'server_error',
+          error_description: `Failed to register client: ${
+            isError(e) ? e.message : 'Unknown error'
+          }`,
+        });
+      }
+    });
+
     return router;
   }
 }
diff --git a/plugins/auth-backend/src/service/OidcService.ts b/plugins/auth-backend/src/service/OidcService.ts
index 5024b2cc8c..919c0dac64 100644
--- a/plugins/auth-backend/src/service/OidcService.ts
+++ b/plugins/auth-backend/src/service/OidcService.ts
@@ -18,6 +18,8 @@ import { TokenIssuer } from '../identity/types';
 import { UserInfoDatabase } from '../database/UserInfoDatabase';
 import { InputError } from '@backstage/errors';
 import { decodeJwt } from 'jose';
+import crypto from 'crypto';
+import { OidcDatabase } from '../database/OidcDatabase';
 
 export class OidcService {
   private constructor(
@@ -25,6 +27,7 @@ export class OidcService {
     private readonly tokenIssuer: TokenIssuer,
     private readonly baseUrl: string,
     private readonly userInfo: UserInfoDatabase,
+    private readonly oidc: OidcDatabase,
   ) {}
 
   static create(options: {
@@ -32,12 +35,14 @@ export class OidcService {
     tokenIssuer: TokenIssuer;
     baseUrl: string;
     userInfo: UserInfoDatabase;
+    oidc: OidcDatabase;
   }) {
     return new OidcService(
       options.auth,
       options.tokenIssuer,
       options.baseUrl,
       options.userInfo,
+      options.oidc,
     );
   }
 
@@ -65,6 +70,8 @@ export class OidcService {
       token_endpoint_auth_methods_supported: [],
       claims_supported: ['sub', 'ent'],
       grant_types_supported: [],
+      authorization_endpoint: `${this.baseUrl}/v1/authorize`,
+      registration_endpoint: `${this.baseUrl}/v1/register`,
     };
   }
 
@@ -89,4 +96,25 @@ export class OidcService {
     }
     return await this.userInfo.getUserInfo(userEntityRef);
   }
+
+  public async registerClient(opts: {
+    responseTypes?: string[];
+    grantTypes?: string[];
+    clientName: string;
+    redirectUris?: string[];
+    scope?: string;
+  }) {
+    const generatedClientId = crypto.randomUUID();
+    const generatedClientSecret = crypto.randomUUID();
+
+    return await this.oidc.createClient({
+      clientId: generatedClientId,
+      clientName: opts.clientName,
+      clientSecret: generatedClientSecret,
+      redirectUris: opts.redirectUris ?? [],
+      responseTypes: opts.responseTypes ?? ['code'],
+      grantTypes: opts.grantTypes ?? ['authorization_code'],
+      scope: opts.scope,
+    });
+  }
 }