OWIN startup class in VB.NET

Question

I'm trying to create an OWIN startup class for Azure AD authentication using a sample project from Microsoft as reference. The sample is in C# but the project I'm adapting it to is in VB.NET so I need to convert the following C# to VB.NET:

public class Startup
{
    // The Client ID is used by the application to uniquely identify itself to Azure AD.
    string clientId = System.Configuration.ConfigurationManager.AppSettings["ClientId"];

    // RedirectUri is the URL where the user will be redirected to after they sign in.
    string redirectUri = System.Configuration.ConfigurationManager.AppSettings["RedirectUri"];

    // Tenant is the tenant ID (e.g. contoso.onmicrosoft.com, or 'common' for multi-tenant)
    static string tenant = System.Configuration.ConfigurationManager.AppSettings["Tenant"];

    // Authority is the URL for authority, composed by Azure Active Directory v2 endpoint and the tenant name (e.g. https://login.microsoftonline.com/contoso.onmicrosoft.com/v2.0)
    string authority = String.Format(System.Globalization.CultureInfo.InvariantCulture, System.Configuration.ConfigurationManager.AppSettings["Authority"], tenant);

    /// <summary>
    /// Configure OWIN to use OpenIdConnect 
    /// </summary>
    /// <param name="app"></param>
    public void Configuration(IAppBuilder app)
    {
        app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);

        app.UseCookieAuthentication(new CookieAuthenticationOptions());
        app.UseOpenIdConnectAuthentication(
            new OpenIdConnectAuthenticationOptions
            {
                // Sets the ClientId, authority, RedirectUri as obtained from web.config
                ClientId = clientId,
                Authority = authority,
                RedirectUri = redirectUri,
                // PostLogoutRedirectUri is the page that users will be redirected to after sign-out. In this case, it is using the home page
                PostLogoutRedirectUri = redirectUri,
                Scope = OpenIdConnectScope.OpenIdProfile,
                // ResponseType is set to request the id_token - which contains basic information about the signed-in user
                ResponseType = OpenIdConnectResponseType.IdToken,
                // ValidateIssuer set to false to allow personal and work accounts from any organization to sign in to your application
                // To only allow users from a single organizations, set ValidateIssuer to true and 'tenant' setting in web.config to the tenant name
                // To allow users from only a list of specific organizations, set ValidateIssuer to true and use ValidIssuers parameter 
                TokenValidationParameters = new TokenValidationParameters()
                {
                    ValidateIssuer = false
                },
                // OpenIdConnectAuthenticationNotifications configures OWIN to send notification of failed authentications to OnAuthenticationFailed method
                Notifications = new OpenIdConnectAuthenticationNotifications
                {
                    AuthenticationFailed = OnAuthenticationFailed
                }
            }
        );
    }

    /// <summary>
    /// Handle failed authentication requests by redirecting the user to the home page with an error in the query string
    /// </summary>
    /// <param name="context"></param>
    /// <returns></returns>
    private Task OnAuthenticationFailed(AuthenticationFailedNotification<OpenIdConnectMessage, OpenIdConnectAuthenticationOptions> context)
    {
        context.HandleResponse();
        context.Response.Redirect("/?errormessage=" + context.Exception.Message);
        return Task.FromResult(0);
    }
}

Here's my converted VB.NET:

Public Class Startup
    Private clientId As String = ConfigurationManager.AppSettings("ClientId")
    Private redirectUri As String = ConfigurationManager.AppSettings("RedirectUri")
    Shared tenant As String = ConfigurationManager.AppSettings("Tenant")
    Private authority As String = String.Format(Globalization.CultureInfo.InvariantCulture, ConfigurationManager.AppSettings("Authority"), tenant)

    Public Sub Configuration(ByVal app As IAppBuilder)
        app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)
        app.UseCookieAuthentication(New CookieAuthenticationOptions())

        app.UseOpenIdConnectAuthentication(New OpenIdConnectAuthenticationOptions With {
            .ClientId = clientId,
            .Authority = authority,
            .RedirectUri = redirectUri,
            .PostLogoutRedirectUri = redirectUri,
            .Scope = OpenIdConnectScope.OpenIdProfile,
            .ResponseType = OpenIdConnectResponseType.IdToken,
            .TokenValidationParameters = New TokenValidationParameters() With {
                .ValidateIssuer = False
            },
            .Notifications = New OpenIdConnectAuthenticationNotifications With {
                .AuthenticationFailed = OnAuthenticationFailed() '<---ERROR HERE
            }
        })
    End Sub

    Private Function OnAuthenticationFailed(ByVal context As AuthenticationFailedNotification(Of OpenIdConnectMessage, OpenIdConnectAuthenticationOptions)) As Task
        context.HandleResponse()
        context.Response.Redirect("/?errormessage=" & context.Exception.Message)
        Return Task.FromResult(0)
    End Function
End Class

I'm getting an error, though, on the line .AuthenticationFailed = OnAuthenticationFailed(). The error says I need to pass in the context parameter which makes sense but I'm confused about why it wasn't required in the C# version and what I'm supposed to pass in the VB.NET.

Thanks!

Based on the context, I think the `AuthenticationFailed` argument is a delegate. In VB, that means you need to use `AddressOf`, so it should read `.AuthenticationFailed = AddressOf OnAuthenticationFailed`. — Craig, May 29 '19 at 15:45
yes; use AddressOf, like @Craig above said. Note that c# had () after the method, where in vb.net you should remove those. Just like Craig said: .AuthenticationFailed = AddressOf OnAuthenticationFailed — StevieTimes, Aug 28 '20 at 18:08

score 2 · Accepted Answer · edited Oct 05 '20 at 14:02

I ended up just writing the OnAuthenticationFailed() function inline:

Public Sub Configuration(ByVal app As IAppBuilder)
        app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)
        app.UseCookieAuthentication(New CookieAuthenticationOptions())

        app.UseOpenIdConnectAuthentication(New OpenIdConnectAuthenticationOptions With {
            .ClientId = clientId,
            .Authority = authority,
            .RedirectUri = redirectUri,
            .PostLogoutRedirectUri = redirectUri,
            .Scope = OpenIdConnectScope.OpenIdProfile,
            .ResponseType = OpenIdConnectResponseType.IdToken,
            .TokenValidationParameters = New TokenValidationParameters() With {
                .ValidateIssuer = True
            },
            .Notifications = New OpenIdConnectAuthenticationNotifications With {
                .AuthenticationFailed = Function(context)
                                            context.HandleResponse()
                                            context.Response.Redirect(HttpContext.Current.Server.MapPath("~") & "?errormessage=" & context.Exception.Message)
                                            Return Task.FromResult(0)
                                        End Function
            }
        })
End Sub

OWIN startup class in VB.NET

1 Answers1