feat(appcheck): Add support for minting limited-use tokens and custom JTI

etc/firebase-admin.app-check.api.md

@@ -24,6 +24,8 @@ export interface AppCheckToken {
 
 // @public
 export interface AppCheckTokenOptions {
+    jti?: string;
+    limitedUse?: boolean;
     ttlMillis?: number;
 }
 

src/app-check/app-check-api-client-internal.ts

@@ -23,7 +23,7 @@ import {
 import { PrefixedFirebaseError } from '../utils/error';
 import * as utils from '../utils/index';
 import * as validator from '../utils/validator';
-import { AppCheckToken } from './app-check-api'
+import { AppCheckToken, AppCheckTokenOptions } from './app-check-api'
 
 // App Check backend constants
 const FIREBASE_APP_CHECK_V1_API_URL_FORMAT = 'https://firebaseappcheck.googleapis.com/v1/projects/{projectId}/apps/{appId}:exchangeCustomToken';
@@ -58,7 +58,11 @@ export class AppCheckApiClient {
    * @param appId - The mobile App ID.
    * @returns A promise that fulfills with a `AppCheckToken`.
    */
-  public exchangeToken(customToken: string, appId: string): Promise<AppCheckToken> {
+  public exchangeToken(
+    customToken: string,
+    appId: string,
+    options?: AppCheckTokenOptions
+  ): Promise<AppCheckToken> {
     if (!validator.isNonEmptyString(appId)) {
       throw new FirebaseAppCheckError(
         'invalid-argument',
@@ -69,13 +73,34 @@ export class AppCheckApiClient {
         'invalid-argument',
         '`customToken` must be a non-empty string.');
     }
+    if (typeof options?.limitedUse !== 'undefined' && !validator.isBoolean(options.limitedUse)) {
+      throw new FirebaseAppCheckError(
+        'invalid-argument',
+        '`limitedUse` must be a boolean value.');
+    }
+    if (typeof options?.jti !== 'undefined') {
+      if (!validator.isString(options.jti)) {
+        throw new FirebaseAppCheckError(
+          'invalid-argument',
+          '`jti` must be a string value.');
+      }
+      if (options.jti !== '' && !options.limitedUse) {
+        throw new FirebaseAppCheckError(
+          'invalid-argument',
+          '`jti` cannot be specified without setting `limitedUse` to `true`.');
+      }
+    }
     return this.getUrl(appId)
       .then((url) => {
         const request: HttpRequestConfig = {
           method: 'POST',
           url,
           headers: FIREBASE_APP_CHECK_CONFIG_HEADERS,
-          data: { customToken }
+          data: {
+            customToken,
+            limitedUse: options?.limitedUse,
+            jti: options?.jti,
+          }
         };
         return this.httpClient.send(request);
       })

src/app-check/app-check-api.ts

@@ -39,6 +39,26 @@ export interface AppCheckTokenOptions {
    * be valid. This value must be between 30 minutes and 7 days, inclusive.
    */
   ttlMillis?: number;
+
+  /**
+   * Specifies whether this token is for a limited use context.
+   * To enable this token to be used with the replay protection feature, set this to `true`.
+   * The default value is `false`.
+   */
+  limitedUse?: boolean;
+
+  /**
+   * Specifies the desired `jti` claim (Section 4.1.7 of RFC 7519) in the returned App
+   * Check token. Limited-use App Check tokens with the same `jti` will be counted as the
+   * same token for the purposes of replay protection.
+   *
+   * If this field is omitted or is empty, a randomly generated `jti` will be used in the
+   * returned App Check token.
+   *
+   * An error is returned if this field is specified without setting `limitedUse` to
+   * `true`.
+   */
+  jti?: string;
 }
 
 /**

src/app-check/app-check.ts

@@ -68,7 +68,7 @@ export class AppCheck {
   public createToken(appId: string, options?: AppCheckTokenOptions): Promise<AppCheckToken> {
     return this.tokenGenerator.createCustomToken(appId, options)
       .then((customToken) => {
-        return this.client.exchangeToken(customToken, appId);
+        return this.client.exchangeToken(customToken, appId, options);
       });
   }
 

test/integration/app-check.spec.ts

@@ -44,7 +44,7 @@ describe('admin.appCheck', () => {
   });
 
   describe('createToken', () => {
-    it('should succeed with a vaild token', function() {
+    it('should succeed with a valid token', function () {
       if (!appId) {
         this.skip();
       }
@@ -53,7 +53,20 @@ describe('admin.appCheck', () => {
           expect(token).to.have.keys(['token', 'ttlMillis']);
           expect(token.token).to.be.a('string').and.to.not.be.empty;
           expect(token.ttlMillis).to.be.a('number');
-          expect(token.ttlMillis).to.equals(3600000);
+          expect(token.ttlMillis).to.equals(3600000); // 1 hour
+        });
+    });
+
+    it('should succeed with a valid limited use token', function () {
+      if (!appId) {
+        this.skip();
+      }
+      return admin.appCheck().createToken(appId as string, { limitedUse: true })
+        .then((token) => {
+          expect(token).to.have.keys(['token', 'ttlMillis']);
+          expect(token.token).to.be.a('string').and.to.not.be.empty;
+          expect(token.ttlMillis).to.be.a('number');
+          expect(token.ttlMillis).to.equals(300000); // 5 minutes
         });
     });
 

test/unit/app-check/app-check-api-client-internal.spec.ts

@@ -210,11 +210,80 @@ describe('AppCheckApiClient', () => {
             method: 'POST',
             url: `https://firebaseappcheck.googleapis.com/v1/projects/test-project/apps/${APP_ID}:exchangeCustomToken`,
             headers: EXPECTED_HEADERS,
-            data: { customToken: TEST_TOKEN_TO_EXCHANGE }
+            data: {
+              customToken: TEST_TOKEN_TO_EXCHANGE,
+              limitedUse: undefined,
+              jti: undefined,
+            }
           });
         });
     });
 
+    it('should resolve with the App Check token on success with limitedUse', () => {
+      const stub = sinon
+        .stub(HttpClient.prototype, 'send')
+        .resolves(utils.responseFrom(TEST_RESPONSE, 200));
+      stubs.push(stub);
+      return apiClient.exchangeToken(TEST_TOKEN_TO_EXCHANGE, APP_ID, { limitedUse: true })
+        .then((resp) => {
+          expect(resp.token).to.deep.equal(TEST_RESPONSE.token);
+          expect(resp.ttlMillis).to.deep.equal(3000);
+          expect(stub).to.have.been.calledOnce.and.calledWith({
+            method: 'POST',
+            url: `https://firebaseappcheck.googleapis.com/v1/projects/test-project/apps/${APP_ID}:exchangeCustomToken`,
+            headers: EXPECTED_HEADERS,
+            data: {
+              customToken: TEST_TOKEN_TO_EXCHANGE,
+              limitedUse: true,
+              jti: undefined,
+            }
+          });
+        });
+    });
+
+    it('should resolve with the App Check token on success with jti', () => {
+      const stub = sinon
+        .stub(HttpClient.prototype, 'send')
+        .resolves(utils.responseFrom(TEST_RESPONSE, 200));
+      stubs.push(stub);
+      return apiClient.exchangeToken(TEST_TOKEN_TO_EXCHANGE, APP_ID, { limitedUse: true, jti: 'test-jti' })
+        .then((resp) => {
+          expect(resp.token).to.deep.equal(TEST_RESPONSE.token);
+          expect(resp.ttlMillis).to.deep.equal(3000);
+          expect(stub).to.have.been.calledOnce.and.calledWith({
+            method: 'POST',
+            url: `https://firebaseappcheck.googleapis.com/v1/projects/test-project/apps/${APP_ID}:exchangeCustomToken`,
+            headers: EXPECTED_HEADERS,
+            data: {
+              customToken: TEST_TOKEN_TO_EXCHANGE,
+              limitedUse: true,
+              jti: 'test-jti',
+            }
+          });
+        });
+    });
+
+    const invalidJtis = [null, NaN, 0, 1, true, false, [], {}, { a: 1 }, _.noop];
+    invalidJtis.forEach((invalidJti) => {
+      it('should throw given a non-string jti: ' + JSON.stringify(invalidJti), () => {
+        expect(() => {
+          apiClient.exchangeToken(TEST_TOKEN_TO_EXCHANGE, APP_ID, { jti: invalidJti as any });
+        }).to.throw('jti` must be a string value.');
+      });
+    });
+
+    it('should throw given jti without limitedUse', () => {
+      expect(() => {
+        apiClient.exchangeToken(TEST_TOKEN_TO_EXCHANGE, APP_ID, { jti: 'test-jti' });
+      }).to.throw('jti` cannot be specified without setting `limitedUse` to `true`.');
+    });
+
+    it('should throw given jti with limitedUse set to false', () => {
+      expect(() => {
+        apiClient.exchangeToken(TEST_TOKEN_TO_EXCHANGE, APP_ID, { jti: 'test-jti', limitedUse: false });
+      }).to.throw('jti` cannot be specified without setting `limitedUse` to `true`.');
+    });
+
     new Map([['3s', 3000], ['4.1s', 4100], ['3.000000001s', 3000], ['3.000001s', 3000]])
       .forEach((ttlMillis, ttlString) => { // value, key, map
         // 3 seconds with 0 nanoseconds expressed as "3s"

test/unit/app-check/app-check.spec.ts

@@ -168,6 +168,35 @@ describe('AppCheck', () => {
           expect(token.ttlMillis).equals(3000);
         });
     });
+
+    it('should resolve with AppCheckToken on success with limitedUse', () => {
+      const response = { token: 'token', ttlMillis: 3000 };
+      const stub = sinon
+        .stub(AppCheckApiClient.prototype, 'exchangeToken')
+        .resolves(response);
+      stubs.push(stub);
+      return appCheck.createToken(APP_ID, { limitedUse: true })
+        .then((token) => {
+          expect(token.token).equals('token');
+          expect(token.ttlMillis).equals(3000);
+          expect(stub).to.have.been.calledOnce.and.calledWith(sinon.match.string, APP_ID, { limitedUse: true });
+        });
+    });
+
+    it('should resolve with AppCheckToken on success with limitedUse and jti', () => {
+      const response = { token: 'token', ttlMillis: 3000 };
+      const stub = sinon
+        .stub(AppCheckApiClient.prototype, 'exchangeToken')
+        .resolves(response);
+      stubs.push(stub);
+      return appCheck.createToken(APP_ID, { limitedUse: true, jti: 'test-jti' })
+        .then((token) => {
+          expect(token.token).equals('token');
+          expect(token.ttlMillis).equals(3000);
+          expect(stub).to.have.been.calledOnce.and.calledWith(
+            sinon.match.string, APP_ID, { limitedUse: true, jti: 'test-jti' });
+        });
+    });
   });
 
   describe('verifyToken', () => {