Add timeouts after verifying the device owner when linking a new device. (#5970)

* Support for waitingForAuth continuation sender during Link new device

* Stop automatically regenerating new QR codes when they expire.

This reverts part of commit e235e3ba81.

* Add a timeout after the Face/TouchID verification when linking a desktop computer.

---------

Co-authored-by: Hugh Nimmo-Smith <hughns@element.io>

ElementX/Sources/FlowCoordinators/LinkNewDeviceFlowCoordinator.swift

@@ -57,7 +57,7 @@ class LinkNewDeviceFlowCoordinator: FlowCoordinatorProtocol {
                 
                 switch action {
                 case .linkMobileDevice(let progressPublisher):
-                    presentQRCodeScreen(mode: .linkMobile(progressPublisher, flowParameters.userSession.clientProxy))
+                    presentQRCodeScreen(mode: .linkMobile(progressPublisher))
                 case .linkDesktopComputer:
                     presentQRCodeScreen(mode: .linkDesktop(flowParameters.userSession.clientProxy.linkNewDeviceService()))
                 case .verifyWithAppLockPIN(let continuation):

ElementX/Sources/Screens/QRCodeLoginScreen/QRCodeLoginScreenModels.swift

@@ -39,7 +39,7 @@ enum QRCodeLoginScreenMode {
     /// Configures the screen to link another device by scanning a QR code.
     case linkDesktop(LinkNewDeviceServiceProtocol)
     /// Configures the screen to link another device by showing it a QR code.
-    case linkMobile(LinkNewDeviceService.LinkMobileProgressPublisher, ClientProxyProtocol)
+    case linkMobile(LinkNewDeviceService.LinkMobileProgressPublisher)
 }
 
 struct QRCodeLoginScreenViewState: BindableState {
@@ -107,7 +107,7 @@ nonisolated enum QRCodeLoginState: Equatable {
     case displayCode(DisplayCodeState)
     
     /// Initial state where the user can link another device using the shown QR code.
-    case displayQR(DisplayQRState)
+    case displayQR(UIImage)
     /// The user needs to enter the two digit code to confirm the channel is secure
     case confirmCode(CheckCodeState)
     
@@ -171,13 +171,6 @@ nonisolated enum QRCodeLoginState: Equatable {
         }
     }
     
-    nonisolated enum DisplayQRState: Equatable {
-        /// The QR code is available and is being shown.
-        case active(UIImage)
-        /// The QR code being shown has expired. We will need to generate a new one.
-        case expired
-    }
-    
     nonisolated enum DisplayCodeState: Equatable {
         case deviceCode(String)
         case verificationCode(String)

ElementX/Sources/Screens/QRCodeLoginScreen/QRCodeLoginScreenViewModel.swift

@@ -13,6 +13,11 @@ typealias QRCodeLoginScreenViewModelType = StateStoreViewModel<QRCodeLoginScreen
 
 class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScreenViewModelProtocol {
     private let appMediator: AppMediatorProtocol
+    /// The time allowed between verifying the device's owner (on the previous screen), to having
+    /// scanned a QR code and established a secure channel for the `linkDesktopComputer` flow.
+    ///
+    /// The generated QR code handles this automatically when linking a mobile device and QR login doesn't need it.
+    private let linkDesktopTimeout: Duration
     
     private let actionsSubject: PassthroughSubject<QRCodeLoginScreenViewModelAction, Never> = .init()
     var actionsPublisher: AnyPublisher<QRCodeLoginScreenViewModelAction, Never> {
@@ -21,18 +26,21 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
     
     private var currentTask: AnyCancellable?
     private var oAuthResultTask: AnyCancellable?
+    private var expirationTask: AnyCancellable?
     
     init(mode: QRCodeLoginScreenMode,
          canSignInManually: Bool,
-         appMediator: AppMediatorProtocol) {
+         appMediator: AppMediatorProtocol,
+         linkDesktopTimeout: Duration = .seconds(120)) {
         self.appMediator = appMediator
+        self.linkDesktopTimeout = linkDesktopTimeout
         
         let initialViewState: QRCodeLoginState = switch mode {
         case .login: .loginInstructions
         case .linkDesktop: .linkDesktopInstructions
-        case .linkMobile(let progressPublisher, _):
+        case .linkMobile(let progressPublisher):
             switch progressPublisher.value {
-            case .qrReady(let image): .displayQR(.active(image))
+            case .qrReady(let image): .displayQR(image)
             default: .error(.unknown)
             }
         }
@@ -40,8 +48,13 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
         super.init(initialViewState: .init(state: initialViewState, mode: mode, canSignInManually: canSignInManually))
         setupSubscriptions()
         
-        if case .linkMobile(let progressPublisher, _) = mode {
+        switch mode {
+        case .linkDesktop:
+            scheduleLinkDesktopExpiration()
+        case .linkMobile(let progressPublisher):
             listenToDisplayQRProgress(progressPublisher: progressPublisher)
+        case .login:
+            break
         }
     }
     
@@ -180,9 +193,10 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
                 case .starting:
                     break // Nothing to do, the state was set above.
                 case .establishingSecureChannel(let checkCodeString):
+                    expirationTask?.cancel()
                     state.state = .displayCode(.deviceCode(checkCodeString))
-                case .waitingForAuthorisation(let url):
-                    requestOAuthAuthorization(url: url)
+                case .waitingForAuthorisation(let verificationURL, let continuationSender):
+                    requestOAuthAuthorization(url: verificationURL, continuationSender: continuationSender)
                 case .syncingSecrets:
                     break // Nothing to do.
                 case .done:
@@ -221,8 +235,8 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
                     break // Nothing to do, we are already showing the code by the time this method is called.
                 case .qrScanned(let checkCodeSender):
                     state.state = .confirmCode(.inputCode(checkCodeSender))
-                case .waitingForAuthorisation(let url):
-                    requestOAuthAuthorization(url: url)
+                case .waitingForAuthorisation(let url, let continuationSender):
+                    requestOAuthAuthorization(url: url, continuationSender: continuationSender)
                 case .syncingSecrets:
                     break // Nothing to do.
                 case .done:
@@ -232,37 +246,29 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
             }
     }
     
-    private func regenerateQRCode() async {
-        guard case .linkMobile(_, let clientProxy) = state.mode else {
-            fatalError("Cannot display a QR code in this mode.")
+    /// Starts the timeout for scanning a desktop's QR code. The flow will expire (cancelling the scan)
+    /// if the secure channel isn't established within the timeout period.
+    private func scheduleLinkDesktopExpiration() {
+        guard case .linkDesktop = state.mode else { fatalError("Expiration requested on an unexpected flow") }
+        
+        expirationTask = Task { [weak self, linkDesktopTimeout] in
+            try? await Task.sleep(for: linkDesktopTimeout, tolerance: .zero)
+            guard !Task.isCancelled else { return }
+            self?.handleExpiration()
+        }
+        .asCancellable()
+    }
+    
+    private func handleExpiration() {
+        // Don't override an error that's already being shown.
+        if case .error = state.state {
+            currentTask = nil // Cancel the scan (just in case).
+            return
         }
         
-        let linkNewDeviceService = clientProxy.linkNewDeviceService()
-        let progressPublisher = linkNewDeviceService.linkMobileDevice()
-        
-        do {
-            async let minimumDelay = Task.sleep(for: .seconds(1)) // To show the spinner for long enough so there isn't a flicker.
-            async let qrReadyProgress = progressPublisher.values
-                .first { progress in
-                    switch progress {
-                    case .qrReady: true
-                    default: false
-                    }
-                }
-            
-            guard case .qrReady(let image) = try await (qrReadyProgress, minimumDelay).0 else {
-                state.state = .error(.unknown)
-                return
-            }
-            
-            state.state = .displayQR(.active(image))
-        } catch let error as QRCodeLoginError {
-            handleError(error)
-        } catch {
-            handleError(.unknown)
-        }
-        
-        listenToDisplayQRProgress(progressPublisher: progressPublisher)
+        MXLog.info("Timed out establishing a secure channel, expiring.")
+        currentTask = nil // Cancel the scan.
+        handleError(.expired)
     }
     
     private func sendCheckCode() async {
@@ -284,7 +290,11 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
         }
     }
     
-    private func requestOAuthAuthorization(url: URL) {
+    private func requestOAuthAuthorization(url: URL, continuationSender: ContinuationMessageSenderProxy) {
+        // There's no OAuth redirect, so the WAS always returns a cancellation failure (both for a declined system prompt and
+        // when closing after successful authorisation). We can't use the continuation as intended, so confirm it and continue.
+        Task { await continuationSender.confirm() }
+        
         let (stream, continuation) = AsyncStream<Result<Void, OAuthError>>.makeStream()
         actionsSubject.send(.requestOAuthAuthorisation(url, continuation))
         
@@ -324,9 +334,6 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
             state.state = .error(.declined)
         case .linkingNotSupported:
             state.state = .error(.linkingNotSupported)
-        case .expired where state.state.isDisplayQR:
-            state.state = .displayQR(.expired)
-            Task { await regenerateQRCode() }
         case .expired:
             state.state = .error(.expired)
         case .slidingSyncNotAvailable:
@@ -341,6 +348,7 @@ class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScr
     /// Only for mocking initial states
     fileprivate init(state: QRCodeLoginState, mode: QRCodeLoginScreenMode, canSignInManually: Bool, checkCodeInput: String) {
         appMediator = AppMediatorMock(.init())
+        linkDesktopTimeout = .seconds(3600)
         super.init(initialViewState: .init(state: state,
                                            mode: mode,
                                            canSignInManually: canSignInManually,

ElementX/Sources/Screens/QRCodeLoginScreen/View/QRCodeLoginScreen.swift

@@ -214,26 +214,19 @@ struct QRCodeLoginScreen: View {
     
     @ViewBuilder
     private var displayQRContent: some View {
-        if case let .displayQR(qrState) = context.viewState.state {
+        if case let .displayQR(image) = context.viewState.state {
             FullscreenDialog(topPadding: 24, horizontalPadding: 24) {
                 VStack(spacing: 32) {
                     TitleAndIcon(title: L10n.screenLinkNewDeviceMobileTitle(InfoPlistReader.main.productionAppName),
                                  icon: \.takePhotoSolid,
                                  iconStyle: .default)
                     
-                    switch qrState {
-                    case .active(let image):
-                        Image(uiImage: image)
-                            .interpolation(.none) // to stop it getting blurred
-                            .resizable()
-                            .scaledToFit()
-                            .frame(width: 200, height: 200)
-                            .accessibilityLabel(L10n.a11yQrCode)
-                    case .expired:
-                        ProgressView()
-                            .controlSize(.large)
-                            .frame(width: 200, height: 200)
-                    }
+                    Image(uiImage: image)
+                        .interpolation(.none) // to stop it getting blurred
+                        .resizable()
+                        .scaledToFit()
+                        .frame(width: 200, height: 200)
+                        .accessibilityLabel(L10n.a11yQrCode)
                     
                     SFNumberedListView(items: context.viewState.instructions.linkMobileItems)
                 }
@@ -351,8 +344,7 @@ struct QRCodeLoginScreen_Previews: PreviewProvider, TestablePreview {
     static let deviceNotSignedInStateViewModel = QRCodeLoginScreenViewModel.mock(state: .scan(.scanFailed(.deviceNotSignedIn)))
     
     /// Showing
-    static let showingStateViewModel = QRCodeLoginScreenViewModel.mock(state: .displayQR(.active(LinkNewDeviceServiceMock.mockQRCodeImage)))
-    static let showingExpiredStateViewModel = QRCodeLoginScreenViewModel.mock(state: .displayQR(.expired))
+    static let showingStateViewModel = QRCodeLoginScreenViewModel.mock(state: .displayQR(LinkNewDeviceServiceMock.mockQRCodeImage))
     
     // Displaying codes
     static let deviceCodeStateViewModel = QRCodeLoginScreenViewModel.mock(state: .displayCode(.deviceCode("12")))
@@ -384,8 +376,6 @@ struct QRCodeLoginScreen_Previews: PreviewProvider, TestablePreview {
         
         ElementNavigationStack { QRCodeLoginScreen(context: showingStateViewModel.context) }
             .previewDisplayName("Showing")
-        ElementNavigationStack { QRCodeLoginScreen(context: showingExpiredStateViewModel.context) }
-            .previewDisplayName("Showing expired")
         
         ElementNavigationStack { QRCodeLoginScreen(context: deviceCodeStateViewModel.context) }
             .previewDisplayName("Device code")

ElementX/Sources/Services/Authentication/AuthenticationService.swift

@@ -377,7 +377,7 @@ private extension HumanQrLoginError {
             .qrCodeError(.deviceNotSignedIn)
         case .UnsupportedQrCodeType:
             .qrCodeError(.invalidQRCode)
-        case .Unknown, .OAuthMetadataInvalid, .CheckCodeAlreadySent, .CheckCodeCannotBeSent, .ContinuationCannotBeSent, .ContinuationAlreadySent:
+        case .Unknown, .OAuthMetadataInvalid, .CheckCodeAlreadySent, .CheckCodeCannotBeSent, .ContinuationAlreadySent, .ContinuationCannotBeSent:
             .qrCodeError(.unknown)
         }
     }

ElementX/Sources/Services/Authentication/LinkNewDeviceService.swift

@@ -29,7 +29,7 @@ class LinkNewDeviceService: LinkNewDeviceServiceProtocol {
         case starting
         case qrReady(UIImage)
         case qrScanned(CheckCodeSenderProxy)
-        case waitingForAuthorisation(verificationURL: URL)
+        case waitingForAuthorisation(verificationURL: URL, continuationSender: ContinuationMessageSenderProxy)
         case syncingSecrets
         case done
     }
@@ -38,7 +38,7 @@ class LinkNewDeviceService: LinkNewDeviceServiceProtocol {
     enum LinkDesktopProgress: Equatable {
         case starting
         case establishingSecureChannel(checkCodeString: String)
-        case waitingForAuthorisation(verificationURL: URL)
+        case waitingForAuthorisation(verificationURL: URL, continuationSender: ContinuationMessageSenderProxy)
         case syncingSecrets
         case done
     }
@@ -163,10 +163,10 @@ extension LinkNewDeviceService.LinkMobileProgress: CustomStringConvertible {
                 throw Error.invalidQRCodeData
             }
         case .qrScanned(let checkCodeSender): .qrScanned(.init(underlyingSender: checkCodeSender))
-        case .waitingForAuth(let verificationURI, _):
+        case .waitingForAuth(let verificationURI, let continuationSender):
             // verificationURI is a String; ASWebAuthenticationSession requires a URL.
             if let url = URL(string: verificationURI) {
-                .waitingForAuthorisation(verificationURL: url)
+                .waitingForAuthorisation(verificationURL: url, continuationSender: .init(underlyingSender: continuationSender))
             } else {
                 throw Error.invalidVerificationURI(verificationURI)
             }
@@ -194,10 +194,10 @@ extension LinkNewDeviceService.LinkDesktopProgress: CustomStringConvertible {
         self = switch rustProgress {
         case .starting: .starting
         case .establishingSecureChannel(_, let checkCodeString): .establishingSecureChannel(checkCodeString: checkCodeString)
-        case .waitingForAuth(let verificationURI, _):
+        case .waitingForAuth(let verificationURI, let continuationSender):
             // verificationURI is a String; ASWebAuthenticationSession requires a URL.
             if let url = URL(string: verificationURI) {
-                .waitingForAuthorisation(verificationURL: url)
+                .waitingForAuthorisation(verificationURL: url, continuationSender: .init(underlyingSender: continuationSender))
             } else {
                 throw Error.invalidVerificationURI(verificationURI)
             }
@@ -240,8 +240,9 @@ private extension QRCodeLoginError {
     }
 }
 
-nonisolated class CheckCodeSenderProxy: Equatable {
+final nonisolated class CheckCodeSenderProxy: Equatable, Sendable {
     static func == (lhs: CheckCodeSenderProxy, rhs: CheckCodeSenderProxy) -> Bool {
+        // Not ideal but good enough as the equality check is purely for removing duplicates from the progress stream.
         lhs.underlyingSender === rhs.underlyingSender
     }
     
@@ -256,6 +257,35 @@ nonisolated class CheckCodeSenderProxy: Equatable {
     }
 }
 
+final nonisolated class ContinuationMessageSenderProxy: Equatable, Sendable {
+    static func == (lhs: ContinuationMessageSenderProxy, rhs: ContinuationMessageSenderProxy) -> Bool {
+        // Not ideal but good enough as the equality check is purely for removing duplicates from the progress stream.
+        lhs.underlyingSender === rhs.underlyingSender
+    }
+    
+    let underlyingSender: ContinuationMessageSenderProtocol
+    
+    init(underlyingSender: ContinuationMessageSenderProtocol) {
+        self.underlyingSender = underlyingSender
+    }
+    
+    func confirm() async {
+        do {
+            try await underlyingSender.confirm()
+        } catch {
+            MXLog.error("Failed to confirm the continuation of the login grant: \(error)")
+        }
+    }
+    
+    func cancel() async {
+        do {
+            try await underlyingSender.cancel()
+        } catch {
+            MXLog.error("Failed to cancel the login grant: \(error)")
+        }
+    }
+}
+
 extension UIImage {
     convenience init?(qrCodeData: Data) {
         let qrContext = CIContext()