The Net::HTTPHeader can't process the HTTP2-Settings header, which is a valid header destined to pass base64-encoded settings to a soon-to-be-upgraded-to-http2 connection.
Although one could say that net-http doesn't support to-http2-upgraded connections and even doesn't provide access to the raw socket, it's still a valid HTTP1.1 header, and the headers current MO "force to downcase and store; capitalize on fetch" works against custom Upgrade headers.
As of now, net-http can't upgrade. I'd suggest an API for such things, in that after a successful Upgrade request (101 switch protocols), the http connection "gives up" the socket to something else.
The Net::HTTPHeader can't process the HTTP2-Settings header, which is a valid header destined to pass base64-encoded settings to a soon-to-be-upgraded-to-http2 connection.
Aren't HTTP header names case-insensitive? What specifically breaks because the string is "Http2-Settings"?
Each header field consists of a case-insensitive field name followed
by a colon (":"), optional leading whitespace, the field value, and
optional trailing whitespace.
In HTTP/1.1 header field names are case-insensitive.
(In HTTP/2 they must be lower-case: https://tools.ietf.org/html/rfc7540#section-8.1.2 ; but that only applies after the upgrade dance has completed and you're encoding into HEADERS frames using HPACK.)
You are right. I just tried with http://nghttp2.org, which supports upgrade-to-http2 http1 requests, and it worked well also with "Http2-Settings". I guess we can close this.