Add limited token support for functions

Author: ssbushi

common/api-review/functions.api.md

@@ -44,6 +44,7 @@ export function httpsCallableFromURL<RequestData = unknown, ResponseData = unkno
 // @public
 export interface HttpsCallableOptions {
     timeout?: number;
+    useLimitedUseAppCheckToken?: boolean;
 }
 
 // @public

packages/app-check-interop-types/index.d.ts

@@ -20,6 +20,10 @@ export interface FirebaseAppCheckInternal {
   // is present. Returns null if no token is present and no token requests are in-flight.
   getToken(forceRefresh?: boolean): Promise<AppCheckTokenResult>;
 
+  // Gets a limited use Firebase App Check token. This method should be used
+  // only if you need to authorize requests to a non-Firebase backend.
+  getLimitedUseToken(): Promise<AppCheckTokenResult>;
+
   // Registers a listener to changes in the token state. There can be more than one listener
   // registered at the same time for one or more FirebaseAppAttestation instances. The
   // listeners call back on the UI thread whenever the current token associated with this

packages/app-check/src/factory.ts

@@ -20,6 +20,7 @@ import { FirebaseApp, _FirebaseService } from '@firebase/app';
 import { FirebaseAppCheckInternal, ListenerType } from './types';
 import {
   getToken,
+  getLimitedUseToken,
   addTokenListener,
   removeTokenListener
 } from './internal-api';
@@ -55,6 +56,7 @@ export function internalFactory(
 ): FirebaseAppCheckInternal {
   return {
     getToken: forceRefresh => getToken(appCheck, forceRefresh),
+    getLimitedUseToken: () => getLimitedUseToken(appCheck),
     addTokenListener: listener =>
       addTokenListener(appCheck, ListenerType.INTERNAL, listener),
     removeTokenListener: listener => removeTokenListener(appCheck.app, listener)

packages/app-check/src/types.ts

@@ -24,6 +24,10 @@ export interface FirebaseAppCheckInternal {
   // is present. Returns null if no token is present and no token requests are in-flight.
   getToken(forceRefresh?: boolean): Promise<AppCheckTokenResult>;
 
+  // Get a Limited use Firebase App Check token. This method should be used
+  // only if you need to authorize requests to a non-Firebase backend. Returns null if no token is present and no token requests are in-flight.
+  getLimitedUseToken(): Promise<AppCheckTokenResult>;
+
   // Registers a listener to changes in the token state. There can be more than one listener
   // registered at the same time for one or more FirebaseAppAttestation instances. The
   // listeners call back on the UI thread whenever the current token associated with this