feat: Let InteractionCompleter return redirect URL

src/identity/IdentityProviderHttpHandler.ts

@@ -1,6 +1,7 @@
 import urljoin from 'url-join';
 import type { ErrorHandler } from '../ldp/http/ErrorHandler';
 import type { RequestParser } from '../ldp/http/RequestParser';
+import { RedirectResponseDescription } from '../ldp/http/response/RedirectResponseDescription';
 import type { ResponseWriter } from '../ldp/http/ResponseWriter';
 import type { Operation } from '../ldp/operations/Operation';
 import type { RepresentationPreferences } from '../ldp/representation/RepresentationPreferences';
@@ -15,11 +16,9 @@ import { assertError, createErrorMessage } from '../util/errors/ErrorUtil';
 import { InternalServerError } from '../util/errors/InternalServerError';
 import { trimTrailingSlashes } from '../util/PathUtil';
 import type { ProviderFactory } from './configuration/ProviderFactory';
-import type {
-  Interaction,
+import type { Interaction,
   InteractionHandler,
-  InteractionHandlerResult,
-} from './interaction/email-password/handler/InteractionHandler';
+  InteractionHandlerResult } from './interaction/email-password/handler/InteractionHandler';
 import { IdpInteractionError } from './interaction/util/IdpInteractionError';
 import type { InteractionCompleter } from './interaction/util/InteractionCompleter';
 
@@ -159,7 +158,8 @@ export class IdentityProviderHttpHandler extends HttpHandler {
         );
       }
       // We need the original request object for the OIDC library
-      return await this.interactionCompleter.handleSafe({ ...result.details, request, response });
+      const location = await this.interactionCompleter.handleSafe({ ...result.details, request });
+      return await this.responseWriter.handleSafe({ response, result: new RedirectResponseDescription(location) });
     }
     if (result.type === 'response' && templateFile) {
       return await this.handleTemplateResponse(response, templateFile, result.details, oidcInteraction);

src/identity/interaction/util/InteractionCompleter.ts

@@ -1,19 +1,26 @@
+import { ServerResponse } from 'http';
 import type { InteractionResults } from 'oidc-provider';
-import type { HttpHandlerInput } from '../../../server/HttpHandler';
+import type { HttpRequest } from '../../../server/HttpRequest';
 import { AsyncHandler } from '../../../util/handlers/AsyncHandler';
 import type { ProviderFactory } from '../../configuration/ProviderFactory';
 
+/**
+ * Parameters required to specify how the interaction should be completed.
+ */
 export interface InteractionCompleterParams {
   webId: string;
   shouldRemember?: boolean;
 }
 
-export type InteractionCompleterInput = HttpHandlerInput & InteractionCompleterParams;
+export interface InteractionCompleterInput extends InteractionCompleterParams {
+  request: HttpRequest;
+}
 
 /**
  * Completes an IDP interaction, logging the user in.
+ * Returns the URL the request should be redirected to.
  */
-export class InteractionCompleter extends AsyncHandler<InteractionCompleterInput> {
+export class InteractionCompleter extends AsyncHandler<InteractionCompleterInput, string> {
   private readonly providerFactory: ProviderFactory;
 
   public constructor(providerFactory: ProviderFactory) {
@@ -21,7 +28,7 @@ export class InteractionCompleter extends AsyncHandler<InteractionCompleterInput
     this.providerFactory = providerFactory;
   }
 
-  public async handle(input: InteractionCompleterInput): Promise<void> {
+  public async handle(input: InteractionCompleterInput): Promise<string> {
     const provider = await this.providerFactory.getProvider();
     const result: InteractionResults = {
       login: {
@@ -34,6 +41,9 @@ export class InteractionCompleter extends AsyncHandler<InteractionCompleterInput
       },
     };
 
-    return provider.interactionFinished(input.request, input.response, result);
+    // Response object is not actually needed here so we can just mock it like this
+    // to bypass the OIDC library checks.
+    // See https://github.com/panva/node-oidc-provider/discussions/1078
+    return provider.interactionResult(input.request, Object.create(ServerResponse.prototype), result);
   }
 }

src/ldp/http/response/CreatedResponseDescription.ts

@@ -5,7 +5,7 @@ import type { ResourceIdentifier } from '../../representation/ResourceIdentifier
 import { ResponseDescription } from './ResponseDescription';
 
 /**
- * Corresponds to a 201 response, containing the relevant link metadata.
+ * Corresponds to a 201 response, containing the relevant location metadata.
  */
 export class CreatedResponseDescription extends ResponseDescription {
   public constructor(location: ResourceIdentifier) {

src/ldp/http/response/RedirectResponseDescription.ts

@@ -0,0 +1,14 @@
+import { DataFactory } from 'n3';
+import { SOLID_HTTP } from '../../../util/Vocabularies';
+import { RepresentationMetadata } from '../../representation/RepresentationMetadata';
+import { ResponseDescription } from './ResponseDescription';
+
+/**
+ * Corresponds to a 301/302 response, containing the relevant location metadata.
+ */
+export class RedirectResponseDescription extends ResponseDescription {
+  public constructor(location: string, permanently = false) {
+    const metadata = new RepresentationMetadata({ [SOLID_HTTP.location]: DataFactory.namedNode(location) });
+    super(permanently ? 301 : 302, metadata);
+  }
+}