feat: Add RedirectingHttpHandler

* feat: redirect handler

Signed-off-by: Wouter Termont <woutermont@gmail.com>

* chore: rewrite reduction as loop

Signed-off-by: Wouter Termont <woutermont@gmail.com>

* chore: remove example import

Signed-off-by: Wouter Termont <woutermont@gmail.com>

* feat: add more redirect flavours

Signed-off-by: Wouter Termont <woutermont@gmail.com>

* chore: RedirectingHttpHandler with RedirectAllHttpHandler

Signed-off-by: Wouter Termont <woutermont@gmail.com>

* chore: replace RedirectAllHttpHandler with RedirectingHttpHandler

* chore: revert 5956385 (chore: replace RedirectAllHttpHandler with RedirectingHttpHandler)

This reverts commit 5956385c4180e8e8914b9199c4ed6ca8ae7d39fb.

* docs: complete constructor params

Signed-off-by: Wouter Termont <woutermont@gmail.com>

config/http/handler/handlers/redirect.json

@@ -0,0 +1,20 @@
+{
+  "@context": "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^3.0.0/components/context.jsonld",
+  "@graph": [
+    {
+      "comment": "Example handler to configure redirect patterns.",
+      "@id": "urn:solid-server:default:RedirectHandler",
+      "@type": "RedirectingHttpHandler",
+      "redirects": [
+        {
+          "RedirectingHttpHandler:_redirects_key": "/from/(.*)",
+          "RedirectingHttpHandler:_redirects_value": "/to/$1"
+        }
+      ],
+      "baseUrl": { "@id": "urn:solid-server:default:variable:baseUrl" },
+      "targetExtractor": { "@id": "urn:solid-server:default:TargetExtractor" },
+      "responseWriter": { "@id": "urn:solid-server:default:ResponseWriter" },
+      "statusCode": "303"
+    }
+  ]
+}

src/index.ts

@@ -258,6 +258,7 @@ export * from './server/HttpResponse';
 export * from './server/HttpServerFactory';
 export * from './server/OperationHttpHandler';
 export * from './server/ParsingHttpHandler';
+export * from './server/RedirectingHttpHandler';
 export * from './server/WebSocketHandler';
 export * from './server/WebSocketServerFactory';
 

src/server/RedirectingHttpHandler.ts

@@ -0,0 +1,109 @@
+import type { TargetExtractor } from '../http/input/identifier/TargetExtractor';
+import { RedirectResponseDescription } from '../http/output/response/RedirectResponseDescription';
+import type { ResponseWriter } from '../http/output/ResponseWriter';
+import { getLoggerFor } from '../logging/LogUtil';
+import { FoundHttpError } from '../util/errors/FoundHttpError';
+import { MovedPermanentlyHttpError } from '../util/errors/MovedPermanentlyHttpError';
+import { NotImplementedHttpError } from '../util/errors/NotImplementedHttpError';
+import { PermanentRedirectHttpError } from '../util/errors/PermanentRedirectHttpError';
+import type { RedirectHttpError } from '../util/errors/RedirectHttpError';
+import { SeeOtherHttpError } from '../util/errors/SeeOtherHttpError';
+import { TemporaryRedirectHttpError } from '../util/errors/TemporaryRedirectHttpError';
+import { getRelativeUrl, joinUrl } from '../util/PathUtil';
+import type { HttpHandlerInput } from './HttpHandler';
+import { HttpHandler } from './HttpHandler';
+import type { HttpRequest } from './HttpRequest';
+
+const redirectErrorFactories: Record<301 | 302 | 303 | 307 | 308, (location: string) => RedirectHttpError> = {
+  301: (location: string): RedirectHttpError => new MovedPermanentlyHttpError(location),
+  302: (location: string): RedirectHttpError => new FoundHttpError(location),
+  303: (location: string): RedirectHttpError => new SeeOtherHttpError(location),
+  307: (location: string): RedirectHttpError => new TemporaryRedirectHttpError(location),
+  308: (location: string): RedirectHttpError => new PermanentRedirectHttpError(location),
+};
+
+/**
+ * Handler that redirects paths matching given patterns
+ * to their corresponding URL, substituting selected groups.
+ */
+export class RedirectingHttpHandler extends HttpHandler {
+  private readonly logger = getLoggerFor(this);
+  private readonly redirects: {
+    regex: RegExp;
+    redirectPattern: string;
+  }[];
+
+  /**
+   * Creates a handler for the provided redirects.
+   * @param redirects - A mapping between URL patterns.
+   * @param targetExtractor - To extract the target from the request.
+   * @param responseWriter - To write the redirect to the response.
+   * @param statusCode - Desired 30x redirection code (defaults to 308).
+   */
+  public constructor(
+    redirects: Record<string, string>,
+    private readonly baseUrl: string,
+    private readonly targetExtractor: TargetExtractor,
+    private readonly responseWriter: ResponseWriter,
+    private readonly statusCode: 301 | 302 | 303 | 307 | 308 = 308,
+  ) {
+    super();
+
+    // Create an array of (regexp, redirect) pairs
+    this.redirects = Object.keys(redirects).map(
+      (pattern): { regex: RegExp; redirectPattern: string } => ({
+        regex: new RegExp(pattern, 'u'),
+        redirectPattern: redirects[pattern],
+      }),
+    );
+  }
+
+  public async canHandle({ request }: HttpHandlerInput): Promise<void> {
+    // Try to find redirect for target URL
+    await this.findRedirect(request);
+  }
+
+  public async handle({ request, response }: HttpHandlerInput): Promise<void> {
+    // Try to find redirect for target URL
+    const redirect = await this.findRedirect(request);
+
+    // Send redirect response
+    this.logger.info(`Redirecting ${request.url} to ${redirect}`);
+    const result = new RedirectResponseDescription(redirectErrorFactories[this.statusCode](redirect));
+    await this.responseWriter.handleSafe({ response, result });
+  }
+
+  private async findRedirect(request: HttpRequest): Promise<string> {
+    // Retrieve target relative to base URL
+    const target = await getRelativeUrl(this.baseUrl, request, this.targetExtractor);
+
+    // Get groups and redirect of first matching pattern
+    let result;
+    for (const { regex, redirectPattern } of this.redirects) {
+      const match = regex.exec(target);
+      if (match) {
+        result = { match, redirectPattern };
+        break;
+      }
+    }
+
+    // Only return if a redirect is configured for the requested URL
+    if (!result) {
+      throw new NotImplementedHttpError(`No redirect configured for ${target}`);
+    }
+
+    // Build redirect URL from regexp result
+    const { match, redirectPattern } = result;
+    const redirect = match.reduce(
+      (prev, param, index): string => prev.replace(`$${index}`, param),
+      redirectPattern,
+    );
+
+    // Don't redirect if target is already correct
+    if (redirect === target) {
+      throw new NotImplementedHttpError('Target is already correct.');
+    }
+
+    return /^(?:[a-z]+:)?\/\//ui.test(redirect) ? redirect : joinUrl(this.baseUrl, redirect);
+  }
+}

src/util/errors/FoundHttpError.ts

@@ -3,6 +3,7 @@ import { RedirectHttpError } from './RedirectHttpError';
 
 /**
  * Error used for resources that have been moved temporarily.
+ * Methods other than GET may or may not be changed to GET in subsequent requests.
  */
 export class FoundHttpError extends RedirectHttpError {
   public constructor(location: string, message?: string, options?: HttpErrorOptions) {

src/util/errors/MovedPermanentlyHttpError.ts

@@ -3,6 +3,7 @@ import { RedirectHttpError } from './RedirectHttpError';
 
 /**
  * Error used for resources that have been moved permanently.
+ * Methods other than GET may or may not be changed to GET in subsequent requests.
  */
 export class MovedPermanentlyHttpError extends RedirectHttpError {
   public constructor(location: string, message?: string, options?: HttpErrorOptions) {

src/util/errors/PermanentRedirectHttpError.ts

@@ -0,0 +1,16 @@
+import type { HttpErrorOptions } from './HttpError';
+import { RedirectHttpError } from './RedirectHttpError';
+
+/**
+ * Error used for resources that have been moved permanently.
+ * Method and body should not be changed in subsequent requests.
+ */
+export class PermanentRedirectHttpError extends RedirectHttpError {
+  public constructor(location: string, message?: string, options?: HttpErrorOptions) {
+    super(308, location, 'PermanentRedirectHttpError', message, options);
+  }
+
+  public static isInstance(error: any): error is PermanentRedirectHttpError {
+    return RedirectHttpError.isInstance(error) && error.statusCode === 308;
+  }
+}

src/util/errors/SeeOtherHttpError.ts

@@ -0,0 +1,17 @@
+import type { HttpErrorOptions } from './HttpError';
+import { RedirectHttpError } from './RedirectHttpError';
+
+/**
+ * Error used to redirect not to the requested resource itself, but to another page,
+ * for example a representation of a real-world object.
+ * The method used to display this redirected page is always GET.
+ */
+export class SeeOtherHttpError extends RedirectHttpError {
+  public constructor(location: string, message?: string, options?: HttpErrorOptions) {
+    super(303, location, 'SeeOtherHttpError', message, options);
+  }
+
+  public static isInstance(error: any): error is SeeOtherHttpError {
+    return RedirectHttpError.isInstance(error) && error.statusCode === 303;
+  }
+}

src/util/errors/TemporaryRedirectHttpError.ts

@@ -0,0 +1,16 @@
+import type { HttpErrorOptions } from './HttpError';
+import { RedirectHttpError } from './RedirectHttpError';
+
+/**
+ * Error used for resources that have been moved temporarily.
+ * Method and body should not be changed in subsequent requests.
+ */
+export class TemporaryRedirectHttpError extends RedirectHttpError {
+  public constructor(location: string, message?: string, options?: HttpErrorOptions) {
+    super(307, location, 'TemporaryRedirectHttpError', message, options);
+  }
+
+  public static isInstance(error: any): error is TemporaryRedirectHttpError {
+    return RedirectHttpError.isInstance(error) && error.statusCode === 307;
+  }
+}

test/unit/server/RedirectingHttpHandler.test.ts

@@ -0,0 +1,97 @@
+import type { TargetExtractor } from '../../../src/http/input/identifier/TargetExtractor';
+import type { ResponseWriter } from '../../../src/http/output/ResponseWriter';
+import type { ResourceIdentifier } from '../../../src/http/representation/ResourceIdentifier';
+import type { HttpRequest } from '../../../src/server/HttpRequest';
+import type { HttpResponse } from '../../../src/server/HttpResponse';
+import { RedirectingHttpHandler } from '../../../src/server/RedirectingHttpHandler';
+import { joinUrl } from '../../../src/util/PathUtil';
+import { SOLID_HTTP } from '../../../src/util/Vocabularies';
+
+describe('A RedirectingHttpHandler', (): void => {
+  const baseUrl = 'http://test.com/';
+  const request = { method: 'GET' } as HttpRequest;
+  const response = {} as HttpResponse;
+  let targetExtractor: jest.Mocked<TargetExtractor>;
+  let responseWriter: jest.Mocked<ResponseWriter>;
+  let handler: RedirectingHttpHandler;
+
+  beforeEach(async(): Promise<void> => {
+    targetExtractor = {
+      handleSafe: jest.fn(({ request: req }): ResourceIdentifier => ({ path: joinUrl(baseUrl, req.url!) })),
+    } as any;
+
+    responseWriter = { handleSafe: jest.fn() } as any;
+
+    handler = new RedirectingHttpHandler({
+      '/one': '/two',
+      '/from/(.*)': 'http://to/t$1',
+      '/f([aeiou]+)/b([aeiou]+)r': '/f$2/b$1r',
+      '/s(.)me': '/s$1me',
+    }, baseUrl, targetExtractor, responseWriter);
+  });
+
+  afterEach(jest.clearAllMocks);
+
+  it('does not handle requests without URL.', async(): Promise<void> => {
+    await expect(handler.canHandle({ request, response }))
+      .rejects.toThrow('Url must be a string. Received undefined');
+    await expect(handler.handle({ request, response }))
+      .rejects.toThrow('Url must be a string. Received undefined');
+  });
+
+  it('does not handle requests with unconfigured URLs.', async(): Promise<void> => {
+    request.url = '/other';
+    await expect(handler.canHandle({ request, response }))
+      .rejects.toThrow('No redirect configured for /other');
+    await expect(handler.handle({ request, response }))
+      .rejects.toThrow('No redirect configured for /other');
+  });
+
+  it('does not handle requests redirecting to their own target URL.', async(): Promise<void> => {
+    request.url = '/same';
+    await expect(handler.canHandle({ request, response }))
+      .rejects.toThrow('Target is already correct.');
+    await expect(handler.handle({ request, response }))
+      .rejects.toThrow('Target is already correct.');
+  });
+
+  it('handles requests to a known URL.', async(): Promise<void> => {
+    request.url = '/one';
+
+    await expect(handler.handle({ request, response })).resolves.toBeUndefined();
+    expect(responseWriter.handleSafe).toHaveBeenCalledTimes(1);
+    expect(responseWriter.handleSafe).toHaveBeenLastCalledWith({
+      response,
+      result: expect.objectContaining({ statusCode: 308 }),
+    });
+    const { metadata } = responseWriter.handleSafe.mock.calls[0][0].result;
+    expect(metadata?.get(SOLID_HTTP.terms.location)?.value).toBe(joinUrl(baseUrl, '/two'));
+  });
+
+  it('handles correctly substitutes group patterns.', async(): Promise<void> => {
+    request.url = '/fa/boor';
+
+    await handler.handle({ request, response });
+    const { metadata } = responseWriter.handleSafe.mock.calls[0][0].result;
+    expect(metadata?.get(SOLID_HTTP.terms.location)?.value).toBe(joinUrl(baseUrl, '/foo/bar'));
+  });
+
+  it('redirects to an absolute url if provided.', async(): Promise<void> => {
+    request.url = '/from/here';
+
+    await handler.handle({ request, response });
+    const { metadata } = responseWriter.handleSafe.mock.calls[0][0].result;
+    expect(metadata?.get(SOLID_HTTP.terms.location)?.value).toBe('http://to/there');
+  });
+
+  it.each([ 301, 302, 303, 307, 308 ])('redirects with the provided status code: %i.', async(code): Promise<void> => {
+    request.url = '/one';
+    (handler as any).statusCode = code;
+
+    await handler.handle({ request, response });
+    expect(responseWriter.handleSafe).toHaveBeenLastCalledWith({
+      response,
+      result: expect.objectContaining({ statusCode: code }),
+    });
+  });
+});

test/unit/util/errors/RedirectHttpError.test.ts

@@ -1,7 +1,10 @@
 import { FoundHttpError } from '../../../../src/util/errors/FoundHttpError';
 import type { HttpErrorOptions } from '../../../../src/util/errors/HttpError';
 import { MovedPermanentlyHttpError } from '../../../../src/util/errors/MovedPermanentlyHttpError';
+import { PermanentRedirectHttpError } from '../../../../src/util/errors/PermanentRedirectHttpError';
 import { RedirectHttpError } from '../../../../src/util/errors/RedirectHttpError';
+import { SeeOtherHttpError } from '../../../../src/util/errors/SeeOtherHttpError';
+import { TemporaryRedirectHttpError } from '../../../../src/util/errors/TemporaryRedirectHttpError';
 
 class FixedRedirectHttpError extends RedirectHttpError {
   public constructor(location: string, message?: string, options?: HttpErrorOptions) {
@@ -13,6 +16,9 @@ describe('RedirectHttpError', (): void => {
   const errors: [string, number, typeof FixedRedirectHttpError][] = [
     [ 'MovedPermanentlyHttpError', 301, MovedPermanentlyHttpError ],
     [ 'FoundHttpError', 302, FoundHttpError ],
+    [ 'SeeOtherHttpError', 303, SeeOtherHttpError ],
+    [ 'TemporaryRedirectHttpError', 307, TemporaryRedirectHttpError ],
+    [ 'PermanentRedirectHttpError', 308, PermanentRedirectHttpError ],
   ];
 
   describe.each(errors)('%s', (name, statusCode, constructor): void => {