Run a custom method immediately after Azure AD Authentication - asp.net-core

Question

I have an ASP.NET Core Web App which successfully uses Azure AD Authentication. I would like to run a process immediately after a user logs in. I thought I might somehow handle the Redirect URI specified in the Azure app registration but I couldn't figure it out as much of the login process is nicely handled by the .AddAzureAd() method in my Startup.cs.
Can anyone suggest an easy way to call a method or redirect to a razor page after authentication? Preferably something which would not be circumvented by specifying a returnUrl in the initial request.
Update
Between posting the question and seeing the answers I found what might be considered a hack:
Basically I created a service and injected it into my _LoginPartial.cshtml page and then call a method on the service.
...
#inject MyService myService
...
#if (User.Identity.IsAuthenticated)
{
await MyService.MyCustomMethod();
...
}

Answer 1

For running code or changing the redirect url, you could configure OpenIdConnectOptions.
services.AddAuthentication(AzureADDefaults.AuthenticationScheme)
.AddAzureAD(options => Configuration.Bind("AzureAd", options));
services.Configure<OpenIdConnectOptions>(AzureADDefaults.OpenIdScheme, options =>
{
options.Events = new OpenIdConnectEvents
{
OnTokenValidated = ctx =>
{
ctx.Properties.RedirectUri = "/Home/Privacy";
return Task.CompletedTask;
},
};
});
If you want to run code after authentication, you could place your code in the OnTokenValidated.
If you want to change the uri, you could replace /Home/Privacy.

Answer 2

You can define the route in Startup.cs file. I used the sample here.
public void ConfigureServices(IServiceCollection services)
{
services.AddAuthentication(sharedOptions =>
{
sharedOptions.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
sharedOptions.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
})
.AddAzureAd(options => Configuration.Bind("AzureAd", options))
.AddCookie();
services.AddMvc();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
}
app.UseStaticFiles();
app.UseAuthentication();
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Contact}/{id?}");
});
}