Add ability to prevent window content being captured by other apps (Desktop) (element-hq#30098)

t3chguy · Dileep Bandla · commit 8743eaa196c8 · 2025-10-07T11:24:37.000+04:00
* Add ability to prevent window content being captured by other apps (Desktop)

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

* Iterate

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

* Increase coverage

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

* Increase coverage

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

* Improve coverage

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

* Delint

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;

---------

Signed-off-by: Michael Telatynski &lt;7t3chguy@gmail.com&gt;
diff --git a/src/@types/global.d.ts b/src/@types/global.d.ts
@@ -128,13 +128,19 @@ declare global {
     }
 
     interface Electron {
+        // Legacy
         on(channel: ElectronChannel, listener: (event: Event, ...args: any[]) => void): void;
         send(channel: ElectronChannel, ...args: any[]): void;
+        // Initialisation
         initialise(): Promise<{
             protocol: string;
             sessionId: string;
             config: IConfigOptions;
+            supportedSettings: Record<string, boolean>;
         }>;
+        // Settings
+        setSettingValue(settingName: string, value: any): Promise<void>;
+        getSettingValue(settingName: string): Promise<any>;
     }
 
     interface DesktopCapturerSource {
diff --git a/src/components/views/settings/tabs/user/PreferencesUserSettingsTab.tsx b/src/components/views/settings/tabs/user/PreferencesUserSettingsTab.tsx
@@ -357,6 +357,12 @@ export default class PreferencesUserSettingsTab extends React.Component<IProps,
                                 appName: SdkConfig.get().brand,
                             })}
                         />
+                        <SettingsFlag
+                            name="Electron.enableContentProtection"
+                            level={SettingLevel.PLATFORM}
+                            hideIfCannotSet
+                            label={_t("settings|preferences|Electron.enableContentProtection")}
+                        />
                         <SettingsFlag name="Electron.alwaysShowMenuBar" level={SettingLevel.PLATFORM} hideIfCannotSet />
                         <SettingsFlag name="Electron.autoLaunch" level={SettingLevel.PLATFORM} hideIfCannotSet />
                         <SettingsFlag name="Electron.warnBeforeExit" level={SettingLevel.PLATFORM} hideIfCannotSet />
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
@@ -2808,6 +2808,7 @@
             "voip": "Audio and Video calls"
         },
         "preferences": {
+            "Electron.enableContentProtection": "Prevent the window contents from being captured by other apps",
             "Electron.enableHardwareAcceleration": "Enable hardware acceleration (restart %(appName)s to take effect)",
             "always_show_menu_bar": "Always show the window menu bar",
             "autocomplete_delay": "Autocomplete delay (ms)",
diff --git a/src/settings/Settings.tsx b/src/settings/Settings.tsx
@@ -349,6 +349,7 @@ export interface Settings {
     "Electron.alwaysShowMenuBar": IBaseSetting<boolean>;
     "Electron.showTrayIcon": IBaseSetting<boolean>;
     "Electron.enableHardwareAcceleration": IBaseSetting<boolean>;
+    "Electron.enableContentProtection": IBaseSetting<boolean>;
     "mediaPreviewConfig": IBaseSetting<MediaPreviewConfig>;
     "Developer.elementCallUrl": IBaseSetting<string>;
 }
@@ -1383,6 +1384,11 @@ export const SETTINGS: Settings = {
         displayName: _td("settings|preferences|enable_hardware_acceleration"),
         default: true,
     },
+    "Electron.enableContentProtection": {
+        supportedLevels: [SettingLevel.PLATFORM],
+        displayName: _td("settings|preferences|enable_hardware_acceleration"),
+        default: false,
+    },
     "Developer.elementCallUrl": {
         supportedLevels: [SettingLevel.DEVICE],
         displayName: _td("devtools|settings|elementCallUrl"),
diff --git a/src/vector/platform/ElectronPlatform.tsx b/src/vector/platform/ElectronPlatform.tsx
@@ -52,8 +52,6 @@ interface SquirrelUpdate {
 
 const SSO_ID_KEY = "element-desktop-ssoid";
 
-const isMac = navigator.platform.toUpperCase().includes("MAC");
-
 function platformFriendlyName(): string {
     // used to use window.process but the same info is available here
     if (navigator.userAgent.includes("Macintosh")) {
@@ -73,13 +71,6 @@ function platformFriendlyName(): string {
     }
 }
 
-function onAction(payload: ActionPayload): void {
-    // Whitelist payload actions, no point sending most across
-    if (["call_state"].includes(payload.action)) {
-        window.electron!.send("app_onAction", payload);
-    }
-}
-
 function getUpdateCheckStatus(status: boolean | string): UpdateStatus {
     if (status === true) {
         return { status: UpdateCheckStatus.Downloading };
@@ -97,25 +88,27 @@ export default class ElectronPlatform extends BasePlatform {
     private readonly ipc = new IPCManager("ipcCall", "ipcReply");
     private readonly eventIndexManager: BaseEventIndexManager = new SeshatIndexManager();
     private readonly initialised: Promise<void>;
+    private readonly electron: Electron;
     private protocol!: string;
     private sessionId!: string;
     private config!: IConfigOptions;
+    private supportedSettings?: Record<string, boolean>;
 
     public constructor() {
         super();
 
         if (!window.electron) {
             throw new Error("Cannot instantiate ElectronPlatform, window.electron is not set");
         }
+        this.electron = window.electron;
 
-        dis.register(onAction);
         /*
             IPC Call `check_updates` returns:
             true if there is an update available
             false if there is not
             or the error if one is encountered
          */
-        window.electron.on("check_updates", (event, status) => {
+        this.electron.on("check_updates", (event, status) => {
             dis.dispatch<CheckUpdatesPayload>({
                 action: Action.CheckUpdates,
                 ...getUpdateCheckStatus(status),
@@ -124,44 +117,44 @@ export default class ElectronPlatform extends BasePlatform {
 
         // `userAccessToken` (IPC) is requested by the main process when appending authentication
         // to media downloads. A reply is sent over the same channel.
-        window.electron.on("userAccessToken", () => {
-            window.electron!.send("userAccessToken", MatrixClientPeg.get()?.getAccessToken());
+        this.electron.on("userAccessToken", () => {
+            this.electron.send("userAccessToken", MatrixClientPeg.get()?.getAccessToken());
         });
 
         // `homeserverUrl` (IPC) is requested by the main process. A reply is sent over the same channel.
-        window.electron.on("homeserverUrl", () => {
-            window.electron!.send("homeserverUrl", MatrixClientPeg.get()?.getHomeserverUrl());
+        this.electron.on("homeserverUrl", () => {
+            this.electron.send("homeserverUrl", MatrixClientPeg.get()?.getHomeserverUrl());
         });
 
         // `serverSupportedVersions` is requested by the main process when it needs to know if the
         // server supports a particular version. This is primarily used to detect authenticated media
         // support. A reply is sent over the same channel.
-        window.electron.on("serverSupportedVersions", async () => {
-            window.electron!.send("serverSupportedVersions", await MatrixClientPeg.get()?.getVersions());
+        this.electron.on("serverSupportedVersions", async () => {
+            this.electron.send("serverSupportedVersions", await MatrixClientPeg.get()?.getVersions());
         });
 
         // try to flush the rageshake logs to indexeddb before quit.
-        window.electron.on("before-quit", function () {
+        this.electron.on("before-quit", function () {
             logger.log("element-desktop closing");
             rageshake.flush();
         });
 
-        window.electron.on("update-downloaded", this.onUpdateDownloaded);
+        this.electron.on("update-downloaded", this.onUpdateDownloaded);
 
-        window.electron.on("preferences", () => {
+        this.electron.on("preferences", () => {
             dis.fire(Action.ViewUserSettings);
         });
 
-        window.electron.on("userDownloadCompleted", (ev, { id, name }) => {
+        this.electron.on("userDownloadCompleted", (ev, { id, name }) => {
             const key = `DOWNLOAD_TOAST_${id}`;
 
             const onAccept = (): void => {
-                window.electron!.send("userDownloadAction", { id, open: true });
+                this.electron.send("userDownloadAction", { id, open: true });
                 ToastStore.sharedInstance().dismissToast(key);
             };
 
             const onDismiss = (): void => {
-                window.electron!.send("userDownloadAction", { id });
+                this.electron.send("userDownloadAction", { id });
             };
 
             ToastStore.sharedInstance().addOrReplaceToast({
@@ -180,7 +173,7 @@ export default class ElectronPlatform extends BasePlatform {
             });
         });
 
-        window.electron.on("openDesktopCapturerSourcePicker", async () => {
+        this.electron.on("openDesktopCapturerSourcePicker", async () => {
             const { finished } = Modal.createDialog(DesktopCapturerSourcePicker);
             const [source] = await finished;
             // getDisplayMedia promise does not return if no dummy is passed here as source
@@ -192,11 +185,20 @@ export default class ElectronPlatform extends BasePlatform {
         this.initialised = this.initialise();
     }
 
+    protected onAction(payload: ActionPayload): void {
+        super.onAction(payload);
+        // Whitelist payload actions, no point sending most across
+        if (["call_state"].includes(payload.action)) {
+            this.electron.send("app_onAction", payload);
+        }
+    }
+
     private async initialise(): Promise<void> {
-        const { protocol, sessionId, config } = await window.electron!.initialise();
+        const { protocol, sessionId, config, supportedSettings } = await this.electron.initialise();
         this.protocol = protocol;
         this.sessionId = sessionId;
         this.config = config;
+        this.supportedSettings = supportedSettings;
     }
 
     public async getConfig(): Promise<IConfigOptions | undefined> {
@@ -248,7 +250,7 @@ export default class ElectronPlatform extends BasePlatform {
         if (this.notificationCount === count) return;
         super.setNotificationCount(count);
 
-        window.electron!.send("setBadgeCount", count);
+        this.electron.send("setBadgeCount", count);
     }
 
     public supportsNotifications(): boolean {
@@ -288,7 +290,7 @@ export default class ElectronPlatform extends BasePlatform {
     }
 
     public loudNotification(ev: MatrixEvent, room: Room): void {
-        window.electron!.send("loudNotification");
+        this.electron.send("loudNotification");
     }
 
     public needsUrlTooltips(): boolean {
@@ -300,21 +302,16 @@ export default class ElectronPlatform extends BasePlatform {
     }
 
     public supportsSetting(settingName?: string): boolean {
-        switch (settingName) {
-            case "Electron.showTrayIcon": // Things other than Mac support tray icons
-            case "Electron.alwaysShowMenuBar": // This isn't relevant on Mac as Menu bars don't live in the app window
-                return !isMac;
-            default:
-                return true;
-        }
+        if (settingName === undefined) return true;
+        return this.supportedSettings?.[settingName] === true;
     }
 
     public getSettingValue(settingName: string): Promise<any> {
-        return this.ipc.call("getSettingValue", settingName);
+        return this.electron.getSettingValue(settingName);
     }
 
     public setSettingValue(settingName: string, value: any): Promise<void> {
-        return this.ipc.call("setSettingValue", settingName, value);
+        return this.electron.setSettingValue(settingName, value);
     }
 
     public async canSelfUpdate(): Promise<boolean> {
@@ -324,14 +321,14 @@ export default class ElectronPlatform extends BasePlatform {
 
     public startUpdateCheck(): void {
         super.startUpdateCheck();
-        window.electron!.send("check_updates");
+        this.electron.send("check_updates");
     }
 
     public installUpdate(): void {
         // IPC to the main process to install the update, since quitAndInstall
         // doesn't fire the before-quit event so the main process needs to know
         // it should exit.
-        window.electron!.send("install_update");
+        this.electron.send("install_update");
     }
 
     public getDefaultDeviceDisplayName(): string {
diff --git a/test/test-utils/test-utils.ts b/test/test-utils/test-utils.ts
@@ -99,6 +99,7 @@ export function createTestClient(): MatrixClient {
         getDevices: jest.fn().mockResolvedValue({ devices: [{ device_id: "ABCDEFGHI" }] }),
         getSessionId: jest.fn().mockReturnValue("iaszphgvfku"),
         credentials: { userId: "@userId:matrix.org" },
+        getAccessToken: jest.fn(),
 
         secretStorage: {
             get: jest.fn(),
diff --git a/test/unit-tests/vector/platform/ElectronPlatform-test.ts b/test/unit-tests/vector/platform/ElectronPlatform-test.ts
@@ -8,7 +8,7 @@ Please see LICENSE files in the repository root for full details.
 
 import { logger } from "matrix-js-sdk/src/logger";
 import { MatrixEvent, Room } from "matrix-js-sdk/src/matrix";
-import { mocked } from "jest-mock";
+import { mocked, type MockedObject } from "jest-mock";
 
 import { UpdateCheckStatus } from "../../../../src/BasePlatform";
 import { Action } from "../../../../src/dispatcher/actions";
@@ -19,6 +19,7 @@ import Modal from "../../../../src/Modal";
 import DesktopCapturerSourcePicker from "../../../../src/components/views/elements/DesktopCapturerSourcePicker";
 import ElectronPlatform from "../../../../src/vector/platform/ElectronPlatform";
 import { setupLanguageMock } from "../../../setup/setupLanguage";
+import { stubClient } from "../../../test-utils";
 
 jest.mock("../../../../src/rageshake/rageshake", () => ({
     flush: jest.fn(),
@@ -35,8 +36,11 @@ describe("ElectronPlatform", () => {
             protocol: "io.element.desktop",
             sessionId: "session-id",
             config: { _config: true },
+            supportedSettings: { setting1: false, setting2: true },
         }),
-    };
+        setSettingValue: jest.fn().mockResolvedValue(undefined),
+        getSettingValue: jest.fn().mockResolvedValue(undefined),
+    } as unknown as MockedObject<Electron>;
 
     const dispatchSpy = jest.spyOn(dispatcher, "dispatch");
     const dispatchFireSpy = jest.spyOn(dispatcher, "fire");
@@ -318,4 +322,87 @@ describe("ElectronPlatform", () => {
             );
         });
     });
+
+    describe("authenticated media", () => {
+        it("should respond to relevant ipc requests", async () => {
+            const cli = stubClient();
+            mocked(cli.getAccessToken).mockReturnValue("access_token");
+            mocked(cli.getHomeserverUrl).mockReturnValue("homeserver_url");
+            mocked(cli.getVersions).mockResolvedValue({
+                versions: ["v1.1"],
+                unstable_features: {},
+            });
+
+            new ElectronPlatform();
+
+            const userAccessTokenCall = mockElectron.on.mock.calls.find((call) => call[0] === "userAccessToken");
+            userAccessTokenCall![1]({} as any);
+            const userAccessTokenResponse = mockElectron.send.mock.calls.find((call) => call[0] === "userAccessToken");
+            expect(userAccessTokenResponse![1]).toBe("access_token");
+
+            const homeserverUrlCall = mockElectron.on.mock.calls.find((call) => call[0] === "homeserverUrl");
+            homeserverUrlCall![1]({} as any);
+            const homeserverUrlResponse = mockElectron.send.mock.calls.find((call) => call[0] === "homeserverUrl");
+            expect(homeserverUrlResponse![1]).toBe("homeserver_url");
+
+            const serverSupportedVersionsCall = mockElectron.on.mock.calls.find(
+                (call) => call[0] === "serverSupportedVersions",
+            );
+            await (serverSupportedVersionsCall![1]({} as any) as unknown as Promise<unknown>);
+            const serverSupportedVersionsResponse = mockElectron.send.mock.calls.find(
+                (call) => call[0] === "serverSupportedVersions",
+            );
+            expect(serverSupportedVersionsResponse![1]).toEqual({ versions: ["v1.1"], unstable_features: {} });
+        });
+    });
+
+    describe("settings", () => {
+        let platform: ElectronPlatform;
+        beforeAll(async () => {
+            window.electron = mockElectron;
+            platform = new ElectronPlatform();
+            await platform.getConfig(); // await init
+        });
+
+        it("supportsSetting should return true for the platform", () => {
+            expect(platform.supportsSetting()).toBe(true);
+        });
+
+        it("supportsSetting should return true for available settings", () => {
+            expect(platform.supportsSetting("setting2")).toBe(true);
+        });
+
+        it("supportsSetting should return false for unavailable settings", () => {
+            expect(platform.supportsSetting("setting1")).toBe(false);
+        });
+
+        it("should read setting value over ipc", async () => {
+            mockElectron.getSettingValue.mockResolvedValue("value");
+            await expect(platform.getSettingValue("setting2")).resolves.toEqual("value");
+            expect(mockElectron.getSettingValue).toHaveBeenCalledWith("setting2");
+        });
+
+        it("should write setting value over ipc", async () => {
+            await platform.setSettingValue("setting2", "newValue");
+            expect(mockElectron.setSettingValue).toHaveBeenCalledWith("setting2", "newValue");
+        });
+    });
+
+    it("should forward call_state dispatcher events via ipc", async () => {
+        new ElectronPlatform();
+
+        dispatcher.dispatch(
+            {
+                action: "call_state",
+                state: "connected",
+            },
+            true,
+        );
+
+        const ipcMessage = mockElectron.send.mock.calls.find((call) => call[0] === "app_onAction");
+        expect(ipcMessage![1]).toEqual({
+            action: "call_state",
+            state: "connected",
+        });
+    });
 });
