In the event you’re enthusiastic about Scorching 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 worthwhile to spend a while studying and you could find yourself with a considerably refined checklist 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 might be extra safety in the event that they got here out of a vault or have been even exhausting coded.
DasBlog is a fairly large and funky app and we observed instantly upon Mark upgrading it to .NET 6 that we have been unable to make use of Scorching Reload (through 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 isn’t 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 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 through 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 alter the ASPNETCORE_ENVIRONMENT to “Manufacturing” (both through launch.json, launchsettings, or an atmosphere 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 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) should you run it. You may observe that operating the precise EXE is all the time 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 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'".
Notice that 'connect-src' was not explicitly set,
so 'default-src' is used as a fallback.
That is so much to consider. I began out my ASP.NET Net 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 Net Server? It is all localhost, proper? Effectively, 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 possibly can 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 do exactly wss:, solely in Growth. 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?
In the event you begin utilizing CSP Headers to tighten issues up, be aware and conscious of the headers you want for conveniences like Scorching Reload in Growth versus no matter issues you could 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.
