Cancel OAuth listener if necessary.

Cancel OAuth listener when login dialog is closed, or the user switches between .com and enterprise while waiting for an OAuth callback.

Author: grokys

src/GitHub.App/Services/OAuthCallbackListener.cs

@@ -41,9 +41,6 @@ public OAuthCallbackListener(IHttpListener httpListener)
 
         public async Task<string> Listen(string id, CancellationToken cancel)
         {
-            var internalCancel = new CancellationTokenSource();
-            var combinedCancel = CancellationTokenSource.CreateLinkedTokenSource(cancel, internalCancel.Token);
-
             if (httpListener.IsListening) httpListener.Stop();
             httpListener.Start();
 

src/GitHub.App/ViewModels/LoginTabViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
+using System.Net;
 using System.Reactive;
 using System.Reactive.Linq;
 using System.Reactive.Threading.Tasks;
@@ -23,6 +24,7 @@ namespace GitHub.ViewModels
     public abstract class LoginTabViewModel : ReactiveObject
     {
         static readonly ILogger log = LogManager.ForContext<LoginTabViewModel>();
+        CancellationTokenSource oauthCancel;
 
         protected LoginTabViewModel(
             IConnectionManager connectionManager,
@@ -46,25 +48,12 @@ protected LoginTabViewModel(
                 (x, y) => x.Value && y.Value).ToProperty(this, x => x.CanLogin);
 
             Login = ReactiveCommand.CreateAsyncObservable(this.WhenAny(x => x.CanLogin, x => x.Value), LogIn);
-
-            Login.ThrownExceptions.Subscribe(ex =>
-            {
-                if (ex.IsCriticalException()) return;
-
-                log.Information(ex, "Error logging into '{BaseUri}' as '{UsernameOrEmail}'", BaseUri, UsernameOrEmail);
-                if (ex is Octokit.ForbiddenException)
-                {
-                    Error = new UserError(Resources.LoginFailedForbiddenMessage, ex.Message);
-                }
-                else
-                {
-                    Error = new UserError(ex.Message);
-                }
-            });
+            Login.ThrownExceptions.Subscribe(HandleError);
 
             LoginViaOAuth = ReactiveCommand.CreateAsyncTask(
                 this.WhenAnyValue(x => x.IsLoggingIn, x => !x),
                 LogInViaOAuth);
+            LoginViaOAuth.ThrownExceptions.Subscribe(HandleError);
 
             isLoggingIn = Login.IsExecuting.ToProperty(this, x => x.IsLoggingIn);
 
@@ -146,6 +135,8 @@ public UserError Error
             set { this.RaiseAndSetIfChanged(ref error, value); }
         }
 
+        public void Deactivated() => oauthCancel?.Cancel();
+
         protected abstract IObservable<AuthenticationResult> LogIn(object args);
         protected abstract Task<AuthenticationResult> LogInViaOAuth(object args);
 
@@ -200,13 +191,16 @@ protected IObservable<AuthenticationResult> LogInToHost(HostAddress hostAddress)
 
         protected async Task LoginToHostViaOAuth(HostAddress address)
         {
+            oauthCancel = new CancellationTokenSource();
+
             try
             {
-                await ConnectionManager.LogInViaOAuth(address, CancellationToken.None);
+                await ConnectionManager.LogInViaOAuth(address, oauthCancel.Token);
             }
-            catch (Exception e)
+            finally
             {
-                Error = new UserError(e.Message);
+                oauthCancel.Dispose();
+                oauthCancel = null;
             }
         }
 
@@ -224,5 +218,32 @@ protected virtual Task ResetValidation()
             // noop
             return Task.FromResult(0);
         }
+
+        void HandleError(Exception ex)
+        {
+            // The Windows ERROR_OPERATION_ABORTED error code.
+            const int operationAborted = 995;
+
+            if (ex is HttpListenerException &&
+                ((HttpListenerException)ex).ErrorCode == operationAborted)
+            {
+                // An Oauth listener was aborted, probably because the user closed the login
+                // dialog or switched between the GitHub and Enterprise tabs while listening
+                // for an Oauth callbacl.
+                return;
+            }
+
+            if (ex.IsCriticalException()) return;
+
+            log.Information(ex, "Error logging into '{BaseUri}' as '{UsernameOrEmail}'", BaseUri, UsernameOrEmail);
+            if (ex is Octokit.ForbiddenException)
+            {
+                Error = new UserError(Resources.LoginFailedForbiddenMessage, ex.Message);
+            }
+            else
+            {
+                Error = new UserError(ex.Message);
+            }
+        }
     }
 }

src/GitHub.Exports.Reactive/ViewModels/ILoginToHostViewModel.cs

@@ -74,5 +74,10 @@ public interface ILoginToHostViewModel
         /// Gets an error to display to the user.
         /// </summary>
         UserError Error { get; }
+
+        /// <summary>
+        /// Called when the login UI is hidden or dismissed.
+        /// </summary>
+        void Deactivated();
     }
 }

src/GitHub.VisualStudio/UI/Views/Controls/LoginControl.xaml.cs

@@ -32,6 +32,7 @@ public LoginControl()
                 SetupDotComBindings(d);
                 SetupEnterpriseBindings(d);
                 SetupSelectedAndVisibleTabBindings(d);
+                d(Disposable.Create(Deactivate));
             });
 
             IsVisibleChanged += (s, e) =>
@@ -45,6 +46,27 @@ public LoginControl()
                 x => x.ViewModel.GitHubLogin.LoginViaOAuth,
                 x => x.ViewModel.EnterpriseLogin.LoginViaOAuth)
                 .Subscribe(_ => Application.Current.MainWindow?.Activate());
+
+            hostTabControl.SelectionChanged += (s, e) =>
+            {
+                foreach (var i in e.RemovedItems)
+                {
+                    if (i == dotComTab)
+                    {
+                        ViewModel?.GitHubLogin.Deactivated();
+                    }
+                    else if (i == enterpriseTab)
+                    {
+                        ViewModel?.EnterpriseLogin.Deactivated();
+                    }
+                }
+            };
+        }
+
+        void Deactivate()
+        {
+            ViewModel?.GitHubLogin.Deactivated();
+            ViewModel?.EnterpriseLogin.Deactivated();
         }
 
         void SetupDotComBindings(Action<IDisposable> d)