validate server connection before dismissing login dialogs

backend/servermanager.go

@@ -1,7 +1,9 @@
 package backend
 
 import (
+	"errors"
 	"net/http"
+	"time"
 
 	"github.com/dweymouth/go-subsonic/subsonic"
 	"github.com/google/uuid"
@@ -16,18 +18,15 @@ type ServerManager struct {
 	onLogout          []func()
 }
 
+var ErrUnreachable = errors.New("server is unreachable")
+
 func NewServerManager() *ServerManager {
 	return &ServerManager{}
 }
 
 func (s *ServerManager) ConnectToServer(conf *ServerConfig, password string) error {
-	cli := &subsonic.Client{
-		Client:     &http.Client{},
-		BaseUrl:    conf.Hostname,
-		User:       conf.Username,
-		ClientName: "supersonic",
-	}
-	if err := cli.Authenticate(password); err != nil {
+	cli, err := s.testConnectionAndCreateClient(conf.Hostname, conf.Username, password)
+	if err != nil {
 		return err
 	}
 	s.Server = cli
@@ -38,6 +37,37 @@ func (s *ServerManager) ConnectToServer(conf *ServerConfig, password string) err
 	return nil
 }
 
+func (s *ServerManager) TestConnectionAndAuth(hostname, username, password string) error {
+	err := ErrUnreachable
+	done := make(chan bool)
+	go func() {
+		_, err = s.testConnectionAndCreateClient(hostname, username, password)
+		close(done)
+	}()
+	select {
+	case <-time.After(200 * time.Millisecond):
+		return err
+	case <-done:
+		return err
+	}
+}
+
+func (s *ServerManager) testConnectionAndCreateClient(hostname, username, password string) (*subsonic.Client, error) {
+	cli := &subsonic.Client{
+		Client:     &http.Client{},
+		BaseUrl:    hostname,
+		User:       username,
+		ClientName: "supersonic",
+	}
+	if !cli.Ping() {
+		return nil, ErrUnreachable
+	}
+	if err := cli.Authenticate(password); err != nil {
+		return nil, err
+	}
+	return cli, nil
+}
+
 func (s *ServerManager) Logout() {
 	if s.Server != nil {
 		keyring.Delete(AppName, s.ServerID.String())

ui/controller/controller.go

@@ -42,6 +42,8 @@ func (m Controller) PromptForFirstServer() {
 	d := dialogs.NewAddEditServerDialog("Connect to Server", nil)
 	pop := widget.NewModalPopUp(d, m.MainWindow.Canvas())
 	d.OnSubmit = func() {
+		if m.testConnectionAndUpdateDialogError(d) {
+			// connection is good
 			pop.Hide()
 			server := m.App.Config.AddServer(d.Nickname, d.Host, d.Username)
 			if err := m.App.ServerManager.SetServerPassword(server, d.Password); err != nil {
@@ -50,6 +52,7 @@ func (m Controller) PromptForFirstServer() {
 			}
 			m.DoConnectToServerWorkflow(server)
 		}
+	}
 	pop.Show()
 }
 
@@ -88,13 +91,13 @@ func (c Controller) DoConnectToServerWorkflow(server *backend.ServerConfig) {
 	pass, err := c.App.ServerManager.GetServerPassword(server)
 	if err != nil {
 		log.Printf("error getting password from keyring: %v", err)
-		c.PromptForLogin()
+		c.PromptForLoginAndConnect()
 	} else {
 		c.tryConnectToServer(server, pass)
 	}
 }
 
-func (m Controller) PromptForLogin() {
+func (m Controller) PromptForLoginAndConnect() {
 	// TODO: this will need to be rewritten a bit when we support multi servers
 	// need to make sure the intended server is first in the list passed to NewLoginDialog
 	d := dialogs.NewLoginDialog(m.App.Config.Servers)
@@ -108,28 +111,46 @@ func (m Controller) PromptForLogin() {
 		editD := dialogs.NewAddEditServerDialog("Edit server", server)
 		editPop := widget.NewModalPopUp(editD, m.MainWindow.Canvas())
 		editD.OnSubmit = func() {
+			if m.testConnectionAndUpdateDialogError(editD) {
+				// connection is good
 				editPop.Hide()
 				server.Hostname = editD.Host
 				server.Nickname = editD.Nickname
 				server.Username = editD.Username
 				m.trySetPasswordAndConnectToServer(server, editD.Password)
 			}
+		}
 		editPop.Show()
 	}
 	pop.Show()
 }
 
-func (c Controller) trySetPasswordAndConnectToServer(server *backend.ServerConfig, password string) {
+func (c Controller) trySetPasswordAndConnectToServer(server *backend.ServerConfig, password string) error {
 	if err := c.App.ServerManager.SetServerPassword(server, password); err != nil {
 		log.Printf("error setting keyring credentials: %v", err)
-		// TODO: handle?
+		// TODO: how best to handle this unexpected codepath
+		// fall back to prompting for password on each run of the app?
+		return err
 	}
-	c.tryConnectToServer(server, password)
+	return c.tryConnectToServer(server, password)
 }
 
-func (c Controller) tryConnectToServer(server *backend.ServerConfig, password string) {
+func (c Controller) tryConnectToServer(server *backend.ServerConfig, password string) error {
 	if err := c.App.ServerManager.ConnectToServer(server, password); err != nil {
 		log.Printf("error connecting to server: %v", err)
-		// TODO: surface error to user
+		return err
 	}
+	return nil
+}
+
+func (c Controller) testConnectionAndUpdateDialogError(dlg *dialogs.AddEditServerDialog) bool {
+	err := c.App.ServerManager.TestConnectionAndAuth(dlg.Host, dlg.Username, dlg.Password)
+	if err == backend.ErrUnreachable {
+		dlg.SetErrorText("Could not reach server (wrong hostname?)")
+		return false
+	} else if err != nil {
+		dlg.SetErrorText("Authentication failed (wrong username/password)")
+		return false
+	}
+	return true
 }

ui/dialogs/addeditserverdialog.go

@@ -7,6 +7,7 @@ import (
 	"fyne.io/fyne/v2/container"
 	"fyne.io/fyne/v2/data/binding"
 	"fyne.io/fyne/v2/layout"
+	"fyne.io/fyne/v2/theme"
 	"fyne.io/fyne/v2/widget"
 )
 
@@ -19,6 +20,7 @@ type AddEditServerDialog struct {
 	Password string
 	OnSubmit func()
 
+	errPromptText *widget.RichText
 	container     *fyne.Container
 }
 
@@ -47,6 +49,9 @@ func NewAddEditServerDialog(title string, prefillServer *backend.ServerConfig) *
 			a.OnSubmit()
 		}
 	})
+	a.errPromptText = widget.NewRichTextWithText("")
+	a.errPromptText.Segments[0].(*widget.TextSegment).Style.ColorName = theme.ColorNameError
+	a.errPromptText.Hidden = true
 
 	a.container = container.NewVBox(
 		container.NewHBox(layout.NewSpacer(), titleLabel, layout.NewSpacer()),
@@ -62,14 +67,26 @@ func NewAddEditServerDialog(title string, prefillServer *backend.ServerConfig) *
 		),
 		widget.NewSeparator(),
 		container.NewHBox(
+			a.errPromptText,
 			layout.NewSpacer(),
-			submit))
+			submit),
+	)
 	return a
 }
 
+func (a *AddEditServerDialog) SetErrorText(text string) {
+	a.errPromptText.Segments[0].(*widget.TextSegment).Text = text
+	if text != "" {
+		a.errPromptText.Show()
+	} else {
+		a.errPromptText.Hide()
+	}
+	a.errPromptText.Refresh()
+}
+
 func (a *AddEditServerDialog) MinSize() fyne.Size {
 	a.ExtendBaseWidget(a)
-	return fyne.NewSize(300, a.container.MinSize().Height)
+	return fyne.NewSize(450, a.container.MinSize().Height)
 }
 
 func (a *AddEditServerDialog) CreateRenderer() fyne.WidgetRenderer {

ui/mainwindow.go

@@ -69,7 +69,7 @@ func NewMainWindow(fyneApp fyne.App, appName string, app *backend.App, size fyne
 		m.BrowsingPane.DisableNavigationButtons()
 		m.BrowsingPane.SetPage(nil)
 		m.BrowsingPane.ClearHistory()
-		m.Controller.PromptForLogin()
+		m.Controller.PromptForLoginAndConnect()
 	})
 	m.BrowsingPane.AddSettingsMenuItem("Log Out", app.ServerManager.Logout)
 	m.addNavigationButtons()