When you’re enthusiastic about Sizzling Reload like me AND you additionally need an “A” grade from SecurityHeaders.com (actually, go do that now) then you’ll study in a short time about Content material-Safety-Coverage headers. It’s good to spend a while studying and you might find yourself with a considerably subtle record of allowed issues, scripts, stylesheets, and so on.
In DasBlog Core (the cross platform weblog engine that runs this weblog) Mark Downie makes these configurable and makes use of the NWebSpec ASP.NET Middleware library so as to add the wanted headers.
if (SecurityStyleSources != null && SecurityScriptSources != null && DefaultSources != null)
{
app.UseCsp(choices => choices
.DefaultSources(s => s.Self()
.CustomSources(DefaultSources)
)
.StyleSources(s => s.Self()
.CustomSources(SecurityStyleSources)
.UnsafeInline()
)
.ScriptSources(s => s.Self()
.CustomSources(SecurityScriptSources)
.UnsafeInline()
.UnsafeEval()
)
);
}
Every of these variables comes out of a config file. Sure, it could be extra safety in the event that they got here out of a vault or have been even arduous coded.
DasBlog is a pretty big and funky app and we observed instantly upon Mark upgrading it to .NET 6 that we have been unable to make use of Sizzling Reload (by way of dotnet watch or from VS 2022). We will complain about it, or we are able to find out about the way it works and why it is not working for us!
Keep in mind: Nothing in your laptop is hidden from you.
Beginning with a easy “View Supply” we are able to see a JavaScript embody on the very backside that’s undoubtedly not mine!
<script src="http://feeds.hanselman.com/_framework/aspnetcore-browser-refresh.js"></script>
Okay, this is smart as we all know not solely does HotReload assist C# (code behinds) but in addition Markup by way of Razor Pages and altering CSS! It will undoubtedly want to speak “again house” to the runner which is both “dotnet watch” or VS2022.
If I alter the ASPNETCORE_ENVIRONMENT to “Manufacturing” (both by way of launch.json, launchsettings, or an setting variable like this, I can see that additional HotReload helper script is not there:
C:githubwshotreloadtest>dotnet run --environment="Manufacturing"
Constructing...
data: Microsoft.Internet hosting.Lifetime[14]
Now listening on: https://localhost:7216
data: Microsoft.Internet hosting.Lifetime[14]
Now listening on: http://localhost:5216
Keep in mind: You by no means wish to use dotnet run in manufacturing! It is an SDK constructing command! You will wish to use dotnet exec your.dll, dotnet your.dll, or better of all, in .NET 6 simply name the EXE immediately! .binDebugnet6.0wshotreloadtest.exe in my instance. Why? dotnet run will all the time assume it is in Growth (you actually inform it to revive, construct, and exec in a single run command) for those who run it. You will word that operating the precise EXE is all the time WAY quicker as properly! Do not ship your .NET SDK to your webserver and do not recompile the entire thing on startup in manufacturing!
We will see that that aspnnetcore-browser-refresh.js is the shopper facet of Growth-time HotReload. Taking a look at our browser console we see :
Refused to hook up with 'wss://localhost:62486/'
as a result of it violates the next Content material Safety Coverage
directive: "default-src 'self'".
Be aware that 'connect-src' was not explicitly set,
so 'default-src' is used as a fallback.
That is loads to consider. I began out my ASP.NET Internet App’s center ware saying it was OK to speak “again to myself” however nowhere else.
app.UseCsp(choices => choices.DefaultSources(s => s.Self()));
Hm, self appears affordable, why cannot the browser join BACK to the dotnet run’ed Kestrel Internet Server? It is all localhost, proper? Nicely, particularly it is http://localhost not ws://localhost, and even wss://localhost (that additional s is for safe) so I must explicitly permit ws: or wss: or each, however solely in Growth.
Possibly like this (once more, I am utilizing NWebSpec, however these are simply HTTP Headers so you may actually simply add them if you would like, hardcoded.)
app.UseCsp(choices => choices.DefaultSources(s => s.Self())
.ConnectSources(s => s.CustomSources("wss://localhost:62895")));
However port numbers change, proper? Let’s just do wss:, solely in Growth. Now, if I am utilizing each CSPs and WebSockets (ws:, wss:) in Manufacturing, I will should be intentional about this.
What is the ethical?
When you begin utilizing CSP Headers to tighten issues up, be aware and conscious of the headers you want for conveniences like Sizzling Reload in Growth versus no matter issues you might want in Manufacturing.
Hope this helps prevent a while!
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About Scott
Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, guide, father, diabetic, and Microsoft worker. He’s a failed stand-up comedian, a cornrower, and a e book writer.
