How to allow executable .exe files to be downloaded with ASP.NET Core and UseStaticFiles middleware

In the long process of upgrading this blog and moving it to Azure I've been slowly fixing small bugs and also dealing with the dozens of microsites I have hanging off of hanselman.com. Some were forgotten, and some just keep chugging along. https://www.babysmash.com/ is one of them.

BabySmash is a silly WPF app I wrote 15 years ago for my baby, natch. He's now learning to drive a car, but it still gets thousands of downloads a month. The code is on Github.

The ClickOnce application and manifests hangs off of http://hanselman.com/babysmash, but the /setup.exe returns a 404.

I had assumed that using this simple code in my Startup.cs's Configure() method would enable static files like setup.exe:

app.UseDefaultFiles();

app.UseStaticFiles();

This was naive I suppose as ASP.NET Core is very much locked down by default so you are really encouraged to be specific and there are few unsafe defaults.

UseStaticFiles includes a parameter for options, so I needed to update the list of mappings from extension to mime/type. So this little helper function:

private StaticFileOptions GetStaticFileOptions()

{

    var p = new FileExtensionContentTypeProvider();

    p.Mappings[".exe"] = "application/octect-stream";

    return new StaticFileOptions { ContentTypeProvider = p };

}

and then you pass that StaticFileOptions class into UseStaticFiles.

app.UseStaticFiles(GetStaticFileOptions());

Clearly a "secure by default" decision, but also one that's easily extended for my needs.

Sponsor: Suffering from a lack of clarity around software bugs? Give your customers the experience they deserve and expect with error monitoring from Raygun.com. Installs in minutes, try it today!