Add CryptoApi.getActiveSessionBackupVersion() (#3555)

* stub backupmanager

* Implement `CryptoApi.getActiveSessionBackupVersion`

* Revert unnecessary change

we can do this later, once we have better test coverage

* more test coverage

---------

Co-authored-by: Richard van der Hoff <richard@matrix.org>

spec/integ/crypto/megolm-backup.spec.ts

@@ -18,7 +18,7 @@ import fetchMock from "fetch-mock-jest";
 import "fake-indexeddb/auto";
 
 import { IKeyBackupSession } from "../../../src/crypto/keybackup";
-import { createClient, ICreateClientOpts, IEvent, MatrixClient } from "../../../src";
+import { createClient, CryptoEvent, ICreateClientOpts, IEvent, MatrixClient } from "../../../src";
 import { SyncResponder } from "../../test-utils/SyncResponder";
 import { E2EKeyReceiver } from "../../test-utils/E2EKeyReceiver";
 import { E2EKeyResponder } from "../../test-utils/E2EKeyResponder";
@@ -151,13 +151,9 @@ describe.each(Object.entries(CRYPTO_BACKENDS))("megolm-keys backup (%s)", (backe
         // start after saving the private key
         await aliceClient.startClient();
 
-        // Persuade alice to fetch the device list. Completing the initial sync will make the device list download
-        // outdated device lists (of which our own user will be one).
-        syncResponder.sendOrQueueSyncResponse({});
-        await jest.advanceTimersByTimeAsync(10); // DeviceList has a sleep(5) which we need to make happen
-
         // tell Alice to trust the dummy device that signed the backup, and re-check the backup.
         // XXX: should we automatically re-check after a device becomes verified?
+        await waitForDeviceList();
         await aliceCrypto.setDeviceVerified(testData.TEST_USER_ID, testData.TEST_DEVICE_ID);
         await aliceClient.checkKeyBackup();
 
@@ -170,4 +166,72 @@ describe.each(Object.entries(CRYPTO_BACKENDS))("megolm-keys backup (%s)", (backe
         await awaitDecryption(event, { waitOnDecryptionFailure: true });
         expect(event.getContent()).toEqual("testytest");
     });
+
+    oldBackendOnly("getActiveSessionBackupVersion() should give correct result", async function () {
+        // 404 means that there is no active backup
+        fetchMock.get("express:/_matrix/client/v3/room_keys/version", 404);
+
+        aliceClient = await initTestClient();
+        const aliceCrypto = aliceClient.getCrypto()!;
+        await aliceClient.startClient();
+
+        // tell Alice to trust the dummy device that signed the backup
+        await waitForDeviceList();
+        await aliceCrypto.setDeviceVerified(testData.TEST_USER_ID, testData.TEST_DEVICE_ID);
+        await aliceClient.checkKeyBackup();
+
+        // At this point there is no backup
+        let backupStatus: string | null;
+        backupStatus = await aliceCrypto.getActiveSessionBackupVersion();
+        expect(backupStatus).toBeNull();
+
+        // Serve a backup with no trusted signature
+        const unsignedBackup = JSON.parse(JSON.stringify(testData.SIGNED_BACKUP_DATA));
+        delete unsignedBackup.auth_data.signatures;
+        fetchMock.get("express:/_matrix/client/v3/room_keys/version", unsignedBackup, {
+            overwriteRoutes: true,
+        });
+
+        const checked = await aliceClient.checkKeyBackup();
+        expect(checked?.backupInfo?.version).toStrictEqual(unsignedBackup.version);
+        expect(checked?.trustInfo?.usable).toBeFalsy();
+
+        backupStatus = await aliceCrypto.getActiveSessionBackupVersion();
+        expect(backupStatus).toBeNull();
+
+        // Add a valid signature to the backup
+        fetchMock.get("express:/_matrix/client/v3/room_keys/version", testData.SIGNED_BACKUP_DATA, {
+            overwriteRoutes: true,
+        });
+
+        // check that signaling is working
+        const backupPromise = new Promise<void>((resolve, reject) => {
+            aliceClient.on(CryptoEvent.KeyBackupStatus, (enabled) => {
+                if (enabled) {
+                    resolve();
+                }
+            });
+        });
+
+        const validCheck = await aliceClient.checkKeyBackup();
+        expect(validCheck?.trustInfo?.usable).toStrictEqual(true);
+
+        await backupPromise;
+
+        backupStatus = await aliceCrypto.getActiveSessionBackupVersion();
+        expect(backupStatus).toStrictEqual(testData.SIGNED_BACKUP_DATA.version);
+    });
+
+    /** make sure that the client knows about the dummy device */
+    async function waitForDeviceList(): Promise<void> {
+        // Completing the initial sync will make the device list download outdated device lists (of which our own
+        // user will be one).
+        syncResponder.sendOrQueueSyncResponse({});
+        // DeviceList has a sleep(5) which we need to make happen
+        await jest.advanceTimersByTimeAsync(10);
+
+        // The client should now know about the dummy device
+        const devices = await aliceClient.getCrypto()!.getUserDeviceInfo([TEST_USER_ID]);
+        expect(devices.get(TEST_USER_ID)!.keys()).toContain(TEST_DEVICE_ID);
+    }
 });

spec/unit/rust-crypto/rust-crypto.spec.ts

@@ -569,6 +569,13 @@ describe("RustCrypto", () => {
             expect(new TextDecoder().decode(fetched!)).toEqual(key);
         });
     });
+
+    describe("getActiveSessionBackupVersion", () => {
+        it("returns null", async () => {
+            const rustCrypto = await makeTestRustCrypto();
+            expect(await rustCrypto.getActiveSessionBackupVersion()).toBeNull();
+        });
+    });
 });
 
 /** build a basic RustCrypto instance for testing

src/client.ts

@@ -3294,6 +3294,12 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns true if the client is configured to back up keys to
      *     the server, otherwise false. If we haven't completed a successful check
      *     of key backup status yet, returns null.
+     *
+     * @deprecated Prefer direct access to {@link CryptoApi.getActiveSessionBackupVersion}:
+     *
+     * ```javascript
+     * let enabled = (await client.getCrypto().getActiveSessionBackupVersion()) !== null;
+     * ```
      */
     public getKeyBackupEnabled(): boolean | null {
         if (!this.crypto) {
@@ -3436,6 +3442,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         // If we're currently backing up to this backup... stop.
         // (We start using it automatically in createKeyBackupVersion
         // so this is symmetrical).
+        // TODO: convert this to use crypto.getActiveSessionBackupVersion. And actually check the version.
         if (this.crypto.backupManager.version) {
             this.crypto.backupManager.disableKeyBackup();
         }

src/crypto-api.ts

@@ -325,6 +325,13 @@ export interface CryptoApi {
      * @param key - the backup decryption key
      */
     storeSessionBackupPrivateKey(key: Uint8Array): Promise<void>;
+
+    /**
+     * Get the current status of key backup.
+     *
+     * @returns If automatic key backups are enabled, the `version` of the active backup. Otherwise, `null`.
+     */
+    getActiveSessionBackupVersion(): Promise<string | null>;
 }
 
 /**

src/crypto/index.ts

@@ -1280,6 +1280,18 @@ export class Crypto extends TypedEventEmitter<CryptoEvent, CryptoEventHandlerMap
         });
     }
 
+    /**
+     * Get the current status of key backup.
+     *
+     * Implementation of {@link CryptoApi.getActiveSessionBackupVersion}.
+     */
+    public async getActiveSessionBackupVersion(): Promise<string | null> {
+        if (this.backupManager.getKeyBackupEnabled()) {
+            return this.backupManager.version ?? null;
+        }
+        return null;
+    }
+
     /**
      * Checks that a given cross-signing private key matches a given public key.
      * This can be used by the getCrossSigningKey callback to verify that the

src/rust-crypto/backup.ts

@@ -0,0 +1,25 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+export class RustBackupManager {
+    /**
+     * Get the backup version we are currently backing up to, if any
+     */
+    public async getActiveBackupVersion(): Promise<string | null> {
+        // TODO stub
+        return null;
+    }
+}

src/rust-crypto/rust-crypto.ts

@@ -56,6 +56,7 @@ import { RustVerificationRequest, verificationMethodIdentifierToMethod } from ".
 import { EventType } from "../@types/event";
 import { CryptoEvent } from "../crypto";
 import { TypedEventEmitter } from "../models/typed-event-emitter";
+import { RustBackupManager } from "./backup";
 
 const ALL_VERIFICATION_METHODS = ["m.sas.v1", "m.qr_code.scan.v1", "m.qr_code.show.v1", "m.reciprocate.v1"];
 
@@ -82,6 +83,8 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
     private outgoingRequestProcessor: OutgoingRequestProcessor;
     private crossSigningIdentity: CrossSigningIdentity;
 
+    public readonly backupManager: RustBackupManager;
+
     public constructor(
         /** The `OlmMachine` from the underlying rust crypto sdk. */
         private readonly olmMachine: RustSdkCryptoJs.OlmMachine,
@@ -109,6 +112,7 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         this.outgoingRequestProcessor = new OutgoingRequestProcessor(olmMachine, http);
         this.keyClaimManager = new KeyClaimManager(olmMachine, this.outgoingRequestProcessor);
         this.eventDecryptor = new EventDecryptor(olmMachine);
+        this.backupManager = new RustBackupManager();
 
         // Fire if the cross signing keys are imported from the secret storage
         const onCrossSigningKeysImport = (): void => {
@@ -780,6 +784,15 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         await this.olmMachine.saveBackupDecryptionKey(RustSdkCryptoJs.BackupDecryptionKey.fromBase64(base64Key), "");
     }
 
+    /**
+     * Get the current status of key backup.
+     *
+     * Implementation of {@link CryptoApi#getActiveSessionBackupVersion}.
+     */
+    public async getActiveSessionBackupVersion(): Promise<string | null> {
+        return await this.backupManager.getActiveBackupVersion();
+    }
+
     ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     //
     // SyncCryptoCallbacks implementation