For those who’re enthusiastic about Sizzling Reload like me AND you additionally need an “A” grade from SecurityHeaders.com (actually, go do this now) then you’ll be taught in a short time about Content material-Safety-Coverage headers. It is advisable to spend a while studying and chances are you’ll find yourself with a considerably subtle record of allowed issues, scripts, stylesheets, and many others.
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 will be extra safety in the event that they got here out of a vault or have been even arduous coded.
DasBlog is a fairly large and funky app and we seen instantly upon Mark upgrading it to .NET 6 that we have been unable to make use of Sizzling Reload (through dotnet watch or from VS 2022). We are able to 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 positively 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 through Razor Pages and altering CSS! It might positively want to speak “again dwelling” to the runner which is both “dotnet watch” or VS2022.
If I modify the ASPNETCORE_ENVIRONMENT to “Manufacturing” (both through 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...
information: Microsoft.Internet hosting.Lifetime[14]
Now listening on: https://localhost:7216
information: Microsoft.Internet hosting.Lifetime[14]
Now listening on: http://localhost:5216
Keep in mind: You by no means need to use dotnet run in manufacturing! It is an SDK constructing command! You will need to use dotnet exec your.dll, dotnet your.dll, or better of all, in .NET 6 simply name the EXE straight! .binDebugnet6.0wshotreloadtest.exe in my instance. Why? dotnet run will at all times assume it is in Improvement (you actually inform it to revive, construct, and exec in a single run command) if you happen to run it. You will word that working the precise EXE is at all times WAY quicker as nicely! Do not ship your .NET SDK to your webserver and do not recompile the entire thing on startup in manufacturing!
We are able to see that that aspnnetcore-browser-refresh.js is the consumer aspect of Improvement-time HotReload. our browser console we see :
Refused to connect with 'wss://localhost:62486/'
as a result of it violates the next Content material Safety Coverage
directive: "default-src 'self'".
Notice 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 enable ws: or wss: or each, however solely in Improvement.
Possibly like this (once more, I am utilizing NWebSpec, however these are simply HTTP Headers so you may actually simply add them in order for you, 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 Improvement. Now, if I am utilizing each CSPs and WebSockets (ws:, wss:) in Manufacturing, I am going to should be intentional about this.
What is the ethical?
For those who begin utilizing CSP Headers to tighten issues up, be acutely aware and conscious of the headers you want for conveniences like Sizzling Reload in Improvement versus no matter issues chances are you’ll 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, advisor, father, diabetic, and Microsoft worker. He’s a failed stand-up comedian, a cornrower, and a e book creator.
