How to debug problems in [Authorize] attribute

Question

The problem

That's everything in the title, really. I have an [Authorize] attribute that's always returning 401 and I don't know why. How can I step through the logic behind it?

A little more detail

I'm trying to use Azure AD authorization via JWT tokens. I've done this successfully with other projects, so I'm sure the problem is some minor configuration issue, but as far as I can tell, the only interaction I get to have with [Authorize] is in Startup.cs, where I have this:

app.UseWindowsAzureActiveDirectoryBearerAuthentication(
    new WindowsAzureActiveDirectoryBearerAuthenticationOptions
    {
        TokenValidationParameters = new TokenValidationParameters
        {
            ValidAudience = ConfigurationManager.AppSettings["ida:Audience"],
            SaveSigninToken = true,
        },
        Tenant = ConfigurationManager.AppSettings["ida:Tenant"]
    });

But that bit only runs when the application starts. Otherwise, [Authorize] is kind of a black box to me.

Thanks for the help!

Answer 1

try put breakpoint in OnAuthenticationFailed method of JwtBearerEvents class, there you can read exception message and then set your config accordingly

.AddJwtBearer(options =>
            {
                options.Authority = Configuration["OIDC:Authority"];
                options.Audience =  Configuration["OIDC:Audience"];
                options.RequireHttpsMetadata = true;
                options.TokenValidationParameters = new 
                TokenValidationParameters()
                {
                    ValidIssuer = Configuration["OIDC:Issuer"]                        
                };
                options.Events = new JwtBearerEvents
                {                        
                    OnAuthenticationFailed = async ctx => 
                     {
                         var putBreakpointHere = true;
                         var exceptionMessage = ctx.Exception;
                     },
                };
            });