If you happen to’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 be taught in a short time about Content material-Safety-Coverage headers. You must spend a while studying and it’s possible you’ll 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 will be extra safety in the event that they got here out of a vault or had been even laborious coded.
DasBlog is a fairly large and funky app and we seen instantly upon Mark upgrading it to .NET 6 that we had been unable to make use of Sizzling Reload (by way of dotnet watch or from VS 2022). We are able to complain about it, or we are able to study the way it works and why it is not working for us!
Bear 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 help C# (code behinds) but in addition Markup by way of Razor Pages and altering CSS! It could positively want to speak “again house” to the runner which is both “dotnet watch” or VS2022.
If I modify the ASPNETCORE_ENVIRONMENT to “Manufacturing” (both by way of launch.json, launchsettings, or an surroundings variable like this, I can see that further 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
Bear 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 instantly! .binDebugnet6.0wshotreloadtest.exe in my instance. Why? dotnet run will at all times assume it is in Growth (you actually inform it to revive, construct, and exec in a single run command) in case you run it. You will observe that working the precise EXE is at all times WAY sooner as properly! 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 shopper aspect of Growth-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'".
Word that 'connect-src' was not explicitly set,
so 'default-src' is used as a fallback.
That is rather a lot 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 cheap, 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 further s is for safe) so I must explicitly enable ws: or wss: or each, however solely in Growth.
Perhaps like this (once more, I am utilizing NWebSpec, however these are simply HTTP Headers so you may actually simply add them if you’d 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 have to be intentional about this.
What is the ethical?
If you happen to 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 it’s possible 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.
