feat: Add support for agentGroup ACL rules

Co-Authored-By: Ludovico Granata <Ludogranata@gmail.com>

config/ldp/authorization/authorizers/access-checkers/agent-group.json

@@ -0,0 +1,11 @@
+{
+  "@context": "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^1.0.0/components/context.jsonld",
+  "@graph": [
+    {
+      "comment": "Checks if the agent belongs to a group that has access.",
+      "@id": "urn:solid-server:default:AgentGroupAccessChecker",
+      "@type": "AgentGroupAccessChecker",
+      "converter": { "@id": "urn:solid-server:default:RepresentationConverter" }
+    }
+  ]
+}

config/ldp/authorization/authorizers/acl.json

@@ -2,7 +2,8 @@
   "@context": "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^1.0.0/components/context.jsonld",
   "import": [
     "files-scs:config/ldp/authorization/authorizers/access-checkers/agent.json",
-    "files-scs:config/ldp/authorization/authorizers/access-checkers/agent-class.json"
+    "files-scs:config/ldp/authorization/authorizers/access-checkers/agent-class.json",
+    "files-scs:config/ldp/authorization/authorizers/access-checkers/agent-group.json"
   ],
   "@graph": [
     {
@@ -21,7 +22,8 @@
         "@type": "BooleanHandler",
         "handlers": [
           { "@id": "urn:solid-server:default:AgentAccessChecker" },
-          { "@id": "urn:solid-server:default:AgentClassAccessChecker" }
+          { "@id": "urn:solid-server:default:AgentClassAccessChecker" },
+          { "@id": "urn:solid-server:default:AgentGroupAccessChecker" }
         ]
       }
     }

src/authorization/access-checkers/AgentGroupAccessChecker.ts

@@ -0,0 +1,50 @@
+import type { Term } from 'n3';
+import type { ResourceIdentifier } from '../../ldp/representation/ResourceIdentifier';
+import type { RepresentationConverter } from '../../storage/conversion/RepresentationConverter';
+import { fetchDataset } from '../../util/FetchUtil';
+import { promiseSome } from '../../util/PromiseUtil';
+import { readableToQuads } from '../../util/StreamUtil';
+import { ACL, VCARD } from '../../util/Vocabularies';
+import type { AccessCheckerArgs } from './AccessChecker';
+import { AccessChecker } from './AccessChecker';
+
+/**
+ * Checks if the given WebID belongs to a group that has access.
+ * Implements the behaviour of groups from the WAC specification.
+ */
+export class AgentGroupAccessChecker extends AccessChecker {
+  private readonly converter: RepresentationConverter;
+
+  public constructor(converter: RepresentationConverter) {
+    super();
+    this.converter = converter;
+  }
+
+  public async handle({ acl, rule, credentials }: AccessCheckerArgs): Promise<boolean> {
+    if (typeof credentials.webId === 'string') {
+      const { webId } = credentials;
+      const groups = acl.getObjects(rule, ACL.terms.agentGroup, null);
+
+      return await promiseSome(groups.map(async(group: Term): Promise<boolean> =>
+        this.isMemberOfGroup(webId, group)));
+    }
+    return false;
+  }
+
+  /**
+   * Checks if the given agent is member of a given vCard group.
+   * @param webId - WebID of the agent that needs access.
+   * @param group - URL of the vCard group that needs to be checked.
+   *
+   * @returns If the agent is member of the given vCard group.
+   */
+  private async isMemberOfGroup(webId: string, group: Term): Promise<boolean> {
+    const groupDocument: ResourceIdentifier = { path: /^[^#]*/u.exec(group.value)![0] };
+
+    // Fetch the required vCard group file
+    const dataset = await fetchDataset(groupDocument.path, this.converter);
+
+    const quads = await readableToQuads(dataset.data);
+    return quads.countQuads(group, VCARD.terms.hasMember, webId, null) !== 0;
+  }
+}

src/index.ts

@@ -21,6 +21,7 @@ export * from './authorization/WebAclAuthorizer';
 export * from './authorization/access-checkers/AccessChecker';
 export * from './authorization/access-checkers/AgentAccessChecker';
 export * from './authorization/access-checkers/AgentClassAccessChecker';
+export * from './authorization/access-checkers/AgentGroupAccessChecker';
 
 // Identity/Configuration
 export * from './identity/configuration/IdentityProviderFactory';

src/util/Vocabularies.ts

@@ -59,6 +59,7 @@ export const ACL = createUriAndTermNamespace('http://www.w3.org/ns/auth/acl#',
   'accessTo',
   'agent',
   'agentClass',
+  'agentGroup',
   'AuthenticatedAgent',
   'Authorization',
   'default',
@@ -144,6 +145,10 @@ export const VANN = createUriAndTermNamespace('http://purl.org/vocab/vann/',
   'preferredNamespacePrefix',
 );
 
+export const VCARD = createUriAndTermNamespace('http://www.w3.org/2006/vcard/ns#',
+  'hasMember',
+);
+
 export const XSD = createUriAndTermNamespace('http://www.w3.org/2001/XMLSchema#',
   'dateTime',
   'integer',

test/unit/authorization/access-checkers/AgentGroupAccessChecker.test.ts

@@ -0,0 +1,50 @@
+import { DataFactory, Store } from 'n3';
+import type { AccessCheckerArgs } from '../../../../src/authorization/access-checkers/AccessChecker';
+import { AgentGroupAccessChecker } from '../../../../src/authorization/access-checkers/AgentGroupAccessChecker';
+import { BasicRepresentation } from '../../../../src/ldp/representation/BasicRepresentation';
+import type { Representation } from '../../../../src/ldp/representation/Representation';
+import type { RepresentationConverter } from '../../../../src/storage/conversion/RepresentationConverter';
+import { INTERNAL_QUADS } from '../../../../src/util/ContentTypes';
+import * as fetchUtil from '../../../../src/util/FetchUtil';
+import { ACL, VCARD } from '../../../../src/util/Vocabularies';
+const { namedNode, quad } = DataFactory;
+
+describe('An AgentGroupAccessChecker', (): void => {
+  const webId = 'http://test.com/alice/profile/card#me';
+  const groupId = 'http://test.com/group';
+  const acl = new Store();
+  acl.addQuad(namedNode('groupMatch'), ACL.terms.agentGroup, namedNode(groupId));
+  acl.addQuad(namedNode('noMatch'), ACL.terms.agentGroup, namedNode('badGroup'));
+  let fetchMock: jest.SpyInstance;
+  let representation: Representation;
+  const converter: RepresentationConverter = {} as any;
+  let checker: AgentGroupAccessChecker;
+
+  beforeEach(async(): Promise<void> => {
+    const groupQuads = [ quad(namedNode(groupId), VCARD.terms.hasMember, namedNode(webId)) ];
+    representation = new BasicRepresentation(groupQuads, INTERNAL_QUADS, false);
+    fetchMock = jest.spyOn(fetchUtil, 'fetchDataset');
+    fetchMock.mockResolvedValue(representation);
+
+    checker = new AgentGroupAccessChecker(converter);
+  });
+
+  it('can handle all requests.', async(): Promise<void> => {
+    await expect(checker.canHandle(null as any)).resolves.toBeUndefined();
+  });
+
+  it('returns true if the WebID is a valid group member.', async(): Promise<void> => {
+    const input: AccessCheckerArgs = { acl, rule: namedNode('groupMatch'), credentials: { webId }};
+    await expect(checker.handle(input)).resolves.toBe(true);
+  });
+
+  it('returns false if the WebID is not a valid group member.', async(): Promise<void> => {
+    const input: AccessCheckerArgs = { acl, rule: namedNode('noMatch'), credentials: { webId }};
+    await expect(checker.handle(input)).resolves.toBe(false);
+  });
+
+  it('returns false if there are no WebID credentials.', async(): Promise<void> => {
+    const input: AccessCheckerArgs = { acl, rule: namedNode('groupMatch'), credentials: {}};
+    await expect(checker.handle(input)).resolves.toBe(false);
+  });
+});