DevTools: Add Bridge protocol version backend/frontend (facebook#21331)

Add an explicit Bridge protocol version to the frontend and backend components as well as a check during initialization to ensure that both are compatible. If not, the frontend will display either upgrade or downgrade instructions.

Note that only the `react-devtools-core` (React Native) and `react-devtools-inline` (Code Sandbox) packages implement this check. Browser extensions inject their own backend and so the check is unnecessary. (Arguably the `react-devtools-inline` check is also unlikely to be necessary _but_ has been added as an extra guard for use cases such as Replay.io.)

packages/react-devtools-core/src/standalone.js

@@ -217,7 +217,10 @@ function initialize(socket: WebSocket) {
     socket.close();
   });
 
-  store = new Store(bridge, {supportsNativeInspection: false});
+  store = new Store(bridge, {
+    checkBridgeProtocolCompatibility: true,
+    supportsNativeInspection: false,
+  });
 
   log('Connected');
   reload();

packages/react-devtools-inline/src/frontend.js

@@ -21,7 +21,10 @@ import type {FrontendBridge} from 'react-devtools-shared/src/bridge';
 import type {Props} from 'react-devtools-shared/src/devtools/views/DevTools';
 
 export function createStore(bridge: FrontendBridge): Store {
-  return new Store(bridge, {supportsTraceUpdates: true});
+  return new Store(bridge, {
+    checkBridgeProtocolCompatibility: true,
+    supportsTraceUpdates: true,
+  });
 }
 
 export function createBridge(

packages/react-devtools-shared/src/backend/agent.js

@@ -26,6 +26,7 @@ import {
   toggleEnabled as setTraceUpdatesEnabled,
 } from './views/TraceUpdates';
 import {patch as patchConsole, unpatch as unpatchConsole} from './console';
+import {currentBridgeProtocol} from 'react-devtools-shared/src/bridge';
 
 import type {BackendBridge} from 'react-devtools-shared/src/bridge';
 import type {
@@ -176,6 +177,7 @@ export default class Agent extends EventEmitter<{|
     bridge.addListener('clearWarningsForFiberID', this.clearWarningsForFiberID);
     bridge.addListener('copyElementPath', this.copyElementPath);
     bridge.addListener('deletePath', this.deletePath);
+    bridge.addListener('getBridgeProtocol', this.getBridgeProtocol);
     bridge.addListener('getProfilingData', this.getProfilingData);
     bridge.addListener('getProfilingStatus', this.getProfilingStatus);
     bridge.addListener('getOwnersList', this.getOwnersList);
@@ -308,6 +310,10 @@ export default class Agent extends EventEmitter<{|
     return null;
   }
 
+  getBridgeProtocol = () => {
+    this._bridge.send('bridgeProtocol', currentBridgeProtocol);
+  };
+
   getProfilingData = ({rendererID}: {|rendererID: RendererID|}) => {
     const renderer = this._rendererInterfaces[rendererID];
     if (renderer == null) {

packages/react-devtools-shared/src/bridge.js

@@ -20,6 +20,49 @@ import type {StyleAndLayout as StyleAndLayoutPayload} from 'react-devtools-share
 
 const BATCH_DURATION = 100;
 
+// This message specifies the version of the DevTools protocol currently supported by the backend,
+// as well as the earliest NPM version (e.g. "4.13.0") that protocol is supported by on the frontend.
+// This enables an older frontend to display an upgrade message to users for a newer, unsupported backend.
+export type BridgeProtocol = {|
+  // Version supported by the current frontend/backend.
+  version: number,
+
+  // NPM version range that also supports this version.
+  // Note that 'maxNpmVersion' is only set when the version is bumped.
+  minNpmVersion: string,
+  maxNpmVersion: string | null,
+|};
+
+// Bump protocol version whenever a backwards breaking change is made
+// in the messages sent between BackendBridge and FrontendBridge.
+// This mapping is embedded in both frontend and backend builds.
+//
+// The backend protocol will always be the latest entry in the BRIDGE_PROTOCOL array.
+//
+// When an older frontend connects to a newer backend,
+// the backend can send the minNpmVersion and the frontend can display an NPM upgrade prompt.
+//
+// When a newer frontend connects with an older protocol version,
+// the frontend can use the embedded minNpmVersion/maxNpmVersion values to display a downgrade prompt.
+export const BRIDGE_PROTOCOL: Array<BridgeProtocol> = [
+  // This version technically never existed,
+  // but a backwards breaking change was added in 4.11,
+  // so the safest guess to downgrade the frontend would be to version 4.10.
+  {
+    version: 0,
+    minNpmVersion: '<4.11.0',
+    maxNpmVersion: '<4.11.0',
+  },
+  {
+    version: 1,
+    minNpmVersion: '4.13.0',
+    maxNpmVersion: null,
+  },
+];
+
+export const currentBridgeProtocol: BridgeProtocol =
+  BRIDGE_PROTOCOL[BRIDGE_PROTOCOL.length - 1];
+
 type ElementAndRendererID = {|id: number, rendererID: RendererID|};
 
 type Message = {|
@@ -119,6 +162,7 @@ type UpdateConsolePatchSettingsParams = {|
 |};
 
 export type BackendEvents = {|
+  bridgeProtocol: [BridgeProtocol],
   extensionBackendInitialized: [],
   inspectedElement: [InspectedElementPayload],
   isBackendStorageAPISupported: [boolean],
@@ -150,6 +194,7 @@ type FrontendEvents = {|
   clearWarningsForFiberID: [ElementAndRendererID],
   copyElementPath: [CopyElementPathParams],
   deletePath: [DeletePath],
+  getBridgeProtocol: [],
   getOwnersList: [ElementAndRendererID],
   getProfilingData: [{|rendererID: RendererID|}],
   getProfilingStatus: [],

packages/react-devtools-shared/src/devtools/store.js

@@ -29,10 +29,17 @@ import {localStorageGetItem, localStorageSetItem} from '../storage';
 import {__DEBUG__} from '../constants';
 import {printStore} from './utils';
 import ProfilerStore from './ProfilerStore';
+import {
+  BRIDGE_PROTOCOL,
+  currentBridgeProtocol,
+} from 'react-devtools-shared/src/bridge';
 
 import type {Element} from './views/Components/types';
 import type {ComponentFilter, ElementType} from '../types';
-import type {FrontendBridge} from 'react-devtools-shared/src/bridge';
+import type {
+  FrontendBridge,
+  BridgeProtocol,
+} from 'react-devtools-shared/src/bridge';
 
 const debug = (methodName, ...args) => {
   if (__DEBUG__) {
@@ -51,6 +58,7 @@ const LOCAL_STORAGE_RECORD_CHANGE_DESCRIPTIONS_KEY =
   'React::DevTools::recordChangeDescriptions';
 
 type Config = {|
+  checkBridgeProtocolCompatibility?: boolean,
   isProfiling?: boolean,
   supportsNativeInspection?: boolean,
   supportsReloadAndProfile?: boolean,
@@ -76,6 +84,7 @@ export default class Store extends EventEmitter<{|
   supportsNativeStyleEditor: [],
   supportsProfiling: [],
   supportsReloadAndProfile: [],
+  unsupportedBridgeProtocolDetected: [],
   unsupportedRendererVersionDetected: [],
 |}> {
   _bridge: FrontendBridge;
@@ -119,6 +128,10 @@ export default class Store extends EventEmitter<{|
 
   _nativeStyleEditorValidAttributes: $ReadOnlyArray<string> | null = null;
 
+  // Older backends don't support an explicit bridge protocol,
+  // so we should timeout eventually and show a downgrade message.
+  _onBridgeProtocolTimeoutID: TimeoutID | null = null;
+
   // Map of element (id) to the set of elements (ids) it owns.
   // This map enables getOwnersListForElement() to avoid traversing the entire tree.
   _ownersMap: Map<number, Set<number>> = new Map();
@@ -147,6 +160,7 @@ export default class Store extends EventEmitter<{|
   _supportsReloadAndProfile: boolean = false;
   _supportsTraceUpdates: boolean = false;
 
+  _unsupportedBridgeProtocol: BridgeProtocol | null = null;
   _unsupportedRendererVersionDetected: boolean = false;
 
   // Total number of visible elements (within all roots).
@@ -217,6 +231,20 @@ export default class Store extends EventEmitter<{|
     );
 
     this._profilerStore = new ProfilerStore(bridge, this, isProfiling);
+
+    // Verify that the frontend version is compatible with the connected backend.
+    // See github.com/facebook/react/issues/21326
+    if (config != null && config.checkBridgeProtocolCompatibility) {
+      // Older backends don't support an explicit bridge protocol,
+      // so we should timeout eventually and show a downgrade message.
+      this._onBridgeProtocolTimeoutID = setTimeout(
+        this.onBridgeProtocolTimeout,
+        10000,
+      );
+
+      bridge.addListener('bridgeProtocol', this.onBridgeProtocol);
+      bridge.send('getBridgeProtocol');
+    }
   }
 
   // This is only used in tests to avoid memory leaks.
@@ -385,6 +413,10 @@ export default class Store extends EventEmitter<{|
     return this._supportsTraceUpdates;
   }
 
+  get unsupportedBridgeProtocol(): BridgeProtocol | null {
+    return this._unsupportedBridgeProtocol;
+  }
+
   get unsupportedRendererVersionDetected(): boolean {
     return this._unsupportedRendererVersionDetected;
   }
@@ -1168,6 +1200,12 @@ export default class Store extends EventEmitter<{|
       'unsupportedRendererVersion',
       this.onBridgeUnsupportedRendererVersion,
     );
+    bridge.removeListener('bridgeProtocol', this.onBridgeProtocol);
+
+    if (this._onBridgeProtocolTimeoutID !== null) {
+      clearTimeout(this._onBridgeProtocolTimeoutID);
+      this._onBridgeProtocolTimeoutID = null;
+    }
   };
 
   onBackendStorageAPISupported = (isBackendStorageAPISupported: boolean) => {
@@ -1187,4 +1225,30 @@ export default class Store extends EventEmitter<{|
 
     this.emit('unsupportedRendererVersionDetected');
   };
+
+  onBridgeProtocol = (bridgeProtocol: BridgeProtocol) => {
+    if (this._onBridgeProtocolTimeoutID !== null) {
+      clearTimeout(this._onBridgeProtocolTimeoutID);
+      this._onBridgeProtocolTimeoutID = null;
+    }
+
+    if (bridgeProtocol.version !== currentBridgeProtocol.version) {
+      this._unsupportedBridgeProtocol = bridgeProtocol;
+    } else {
+      // If we should happen to get a response after timing out...
+      this._unsupportedBridgeProtocol = null;
+    }
+
+    this.emit('unsupportedBridgeProtocolDetected');
+  };
+
+  onBridgeProtocolTimeout = () => {
+    this._onBridgeProtocolTimeoutID = null;
+
+    // If we timed out, that indicates the backend predates the bridge protocol,
+    // so we can set a fake version (0) to trigger the downgrade message.
+    this._unsupportedBridgeProtocol = BRIDGE_PROTOCOL[0];
+
+    this.emit('unsupportedBridgeProtocolDetected');
+  };
 }

packages/react-devtools-shared/src/devtools/views/DevTools.js

@@ -25,6 +25,7 @@ import ViewElementSourceContext from './Components/ViewElementSourceContext';
 import {ProfilerContextController} from './Profiler/ProfilerContext';
 import {ModalDialogContextController} from './ModalDialog';
 import ReactLogo from './ReactLogo';
+import UnsupportedBridgeProtocolDialog from './UnsupportedBridgeProtocolDialog';
 import UnsupportedVersionDialog from './UnsupportedVersionDialog';
 import WarnIfLegacyBackendDetected from './WarnIfLegacyBackendDetected';
 import {useLocalStorage} from './hooks';
@@ -226,6 +227,7 @@ export default function DevTools({
                 </TreeContextController>
               </ViewElementSourceContext.Provider>
             </SettingsContextController>
+            <UnsupportedBridgeProtocolDialog />
             {warnIfLegacyBackendDetected && <WarnIfLegacyBackendDetected />}
             {warnIfUnsupportedVersionDetected && <UnsupportedVersionDialog />}
           </ModalDialogContextController>

packages/react-devtools-shared/src/devtools/views/Settings/SettingsContext.js

@@ -383,6 +383,13 @@ export function updateThemeVariables(
   updateStyleHelper(theme, 'color-expand-collapse-toggle', documentElements);
   updateStyleHelper(theme, 'color-link', documentElements);
   updateStyleHelper(theme, 'color-modal-background', documentElements);
+  updateStyleHelper(
+    theme,
+    'color-bridge-version-npm-background',
+    documentElements,
+  );
+  updateStyleHelper(theme, 'color-bridge-version-npm-text', documentElements);
+  updateStyleHelper(theme, 'color-bridge-version-number', documentElements);
   updateStyleHelper(
     theme,
     'color-primitive-hook-badge-background',

packages/react-devtools-shared/src/devtools/views/UnsupportedBridgeProtocolDialog.css

@@ -0,0 +1,37 @@
+.Column { 
+  display: flex;  
+  flex-direction: column; 
+} 
+
+.Title {  
+  font-size: var(--font-size-sans-large); 
+  margin-bottom: 0.5rem;  
+} 
+
+.ReleaseNotesLink { 
+  color: var(--color-button-active);  
+}
+
+.Version {
+  color: var(--color-bridge-version-number);
+  font-weight: bold;
+}
+
+.NpmCommand {
+  display: flex;
+  justify-content: space-between;
+  padding: 0.25rem 0.25rem 0.25rem 0.5rem;
+  background-color: var(--color-bridge-version-npm-background);
+  color: var(--color-bridge-version-npm-text);
+  margin: 0;
+  font-family: var(--font-family-monospace);
+  font-size: var(--font-size-monospace-large);
+}
+
+.Paragraph {
+  margin: 0.5rem 0;
+}
+
+.Link {
+  color: var(--color-link);
+}