Implement a fast lookup for wildcard certificates

[arontsang]

No description provided.

[gfoidl]

Nit: there are quite a few blank lines that could be removed too.

[gfoidl]

You compare it backwards?
Is it better then, to write the loop backwards and have normal index access?

[gfoidl]

So the JIT can't elide the bound-check for indexing into the spans.
I think it's better to slice the spans to the common (= min) length and use one span in the loop, in order to elide at least one bound check (the JIT should handle the downward loop (see other comment) in a recent version).

Roughly:

Suggested change

	var length = Math.Min(x.Length, y.Length);
	for (var i = 1; i <= length; i++)
	if (x.Length < y.Length)
	{
	y = y.Slice(0, x.Length);
	}
	else if (y.Length < x.Length)
	{
	x = x.Slice(0, y.Length);
	}
	for (var i = x.Length; i >= 1; --i)

[KLuuKer]

domainName CAN BE NULL!
when SNI is not available.

https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.server.kestrel.https.httpsconnectionadapteroptions.servercertificateselector?view=aspnetcore-9.0