HTTP/3: Write static header names

[JamesNK]

Map known headers to QPACK static table. Write name id instead of full value when header is in the static table.

[halter73]

We should consider adding the un-"known" response headers given the methodology described in the quickwg QPACK static table appendix.

I also think the following headers only make sense on the request: Cookie, Authorization, UserAgent, Referer, Origin, IfModifiedSince, IfNoneMatch, Method, Accept, AcceptEncoding, AcceptLanguage, Range, IfRange and UpgradeInsecureRequests

Do we think there would be much value in trying to use the static header values too?

[JamesNK]

I didn't add more known headers because there is a limit to how many we can have. Eventually, the bit flags will be too large for 64bits.

I will look at using the static table for values in a future PR. It will require greater changes.

[Tratcher]

I also think the following headers only make sense on the request: Cookie, Authorization, UserAgent, Referer, Origin, IfModifiedSince, IfNoneMatch, Method, Accept, AcceptEncoding, AcceptLanguage, Range, IfRange and UpgradeInsecureRequests

Yes, remove request headers from this list, if only to make it easier to reason about.

[JamesNK]

For HPACK, we have the complete list:

aspnetcore/src/Servers/Kestrel/Core/src/Internal/Http2/Http2HeadersEnumerator.cs

Lines 149 to 203 in 465f929

	internal static int GetResponseHeaderStaticTableId(KnownHeaderType responseHeaderType)
	{
	switch (responseHeaderType)
	{
	case KnownHeaderType.CacheControl:
	return H2StaticTable.CacheControl;
	case KnownHeaderType.Date:
	return H2StaticTable.Date;
	case KnownHeaderType.TransferEncoding:
	return H2StaticTable.TransferEncoding;
	case KnownHeaderType.Via:
	return H2StaticTable.Via;
	case KnownHeaderType.Allow:
	return H2StaticTable.Allow;
	case KnownHeaderType.ContentType:
	return H2StaticTable.ContentType;
	case KnownHeaderType.ContentEncoding:
	return H2StaticTable.ContentEncoding;
	case KnownHeaderType.ContentLanguage:
	return H2StaticTable.ContentLanguage;
	case KnownHeaderType.ContentLocation:
	return H2StaticTable.ContentLocation;
	case KnownHeaderType.ContentRange:
	return H2StaticTable.ContentRange;
	case KnownHeaderType.Expires:
	return H2StaticTable.Expires;
	case KnownHeaderType.LastModified:
	return H2StaticTable.LastModified;
	case KnownHeaderType.AcceptRanges:
	return H2StaticTable.AcceptRanges;
	case KnownHeaderType.Age:
	return H2StaticTable.Age;
	case KnownHeaderType.ETag:
	return H2StaticTable.ETag;
	case KnownHeaderType.Location:
	return H2StaticTable.Location;
	case KnownHeaderType.ProxyAuthenticate:
	return H2StaticTable.ProxyAuthenticate;
	case KnownHeaderType.RetryAfter:
	return H2StaticTable.RetryAfter;
	case KnownHeaderType.Server:
	return H2StaticTable.Server;
	case KnownHeaderType.SetCookie:
	return H2StaticTable.SetCookie;
	case KnownHeaderType.Vary:
	return H2StaticTable.Vary;
	case KnownHeaderType.WWWAuthenticate:
	return H2StaticTable.WwwAuthenticate;
	case KnownHeaderType.AccessControlAllowOrigin:
	return H2StaticTable.AccessControlAllowOrigin;
	case KnownHeaderType.ContentLength:
	return H2StaticTable.ContentLength;
	default:
	return -1;
	}

Do you want to trim the HPACK list as well? Which items?

Or leave both HPACK and QPACK lists as is?

[Tratcher]

Oh, ok, leave it.

[halter73]

It looks to me that Http2HeadersEnumerator.GetResponseHeaderStaticTableId() only handles response headers. I don't see request headers like Cookie, Authorization or any of the rest in there.

[JamesNK]

You're right. I'll make the change to remove them in another PR.

[halter73]

I like the test reorganization under Http1/Http2/Http3

[Tratcher]

I noticed the status compression is out of date: #38604