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For those who’re enthusiastic about Scorching Reload like me AND you additionally need an “A” grade from SecurityHeaders.com (actually, go do this now) then you’ll study in a short time about Content material-Safety-Coverage headers. You want to spend a while studying and it’s possible you’ll find yourself with a considerably subtle checklist 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 pretty big and funky app and we observed instantly upon Mark upgrading it to .NET 6 that we had been unable to make use of Scorching Reload (by way of dotnet watch or from VS 2022). We will 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 embrace on the very backside that’s undoubtedly not mine!
<script src="http://feeds.hanselman.com/_framework/aspnetcore-browser-refresh.js"></script>
Okay, this is sensible 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 might undoubtedly want to speak “again residence” 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 setting 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 wish to use dotnet run in manufacturing! It is an SDK constructing command! You may wish 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 all the time assume it is in Growth (you actually inform it to revive, construct, and exec in a single run command) when you run it. You may be aware that working the precise EXE is all the time WAY sooner as effectively! 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. 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 further s is for safe) so I must explicitly enable 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’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 must 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 Scorching 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 ebook writer.
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