Snippet to demo how an http module can be used to check pdf requests

PdfModule.cs

public class PdfModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.PostAuthorizeRequest += PostAuthorizeRequest;
    }

    void PostAuthorizeRequest(object sender, EventArgs e)
    {
        var context = HttpContext.Current;
        var url = context.Request.Url.AbsolutePath;
        if (!url.EndsWith(".pdf"))
        {
            return;
        }
        
        // do some logic here, then just return if no further action is needed
    }

    public void Dispose()
    {
    }
}