[quicwg/base-drafts] Is absence of both :authority and Host an error? (#3408)

[Mike Bishop <[e-mail]>]

>From an interop discussion with @martinduke and @kazuho.

HTTP/1.1 [requires](https://httpwg.org/http-core/draft-ietf-httpbis-semantics-latest.html#header.host) the presence of a Host header:
> A client MUST send a Host header field in all HTTP/1.1 request messages. If the target URI includes an authority component, then a client MUST send a field value for Host that is identical to that authority component, excluding any userinfo subcomponent and its "@" delimiter (Section 2.5.1). If the authority component is missing or undefined for the target URI, then a client MUST send a Host header field with an empty field value.
If no Host header is present, the section on [Effective Request URI](https://httpwg.org/http-core/draft-ietf-httpbis-messaging-latest.html#h1.effective.request.uri) describes how you determine what host is being asked for, ending with "heuristics" if it's an HTTP/1.0 request.

HTTP/2 says that you generate an `:authority` pseudo-header if sending direct-to-H2 and carry through the Host header if you're relaying HTTP/1.1.  There is no discussion about what to do with an HTTP/1.0 (or 0.9) request being relayed over HTTP/2, which wouldn't have a Host header; you're neither required to generate or send one, even an empty one, nor are you given guidance about how to figure it out.

HTTP/3 carries forward the H2 language (currently by reference, and explicitly after #3407).  Do we want to have some guidance here?  Or does this issue instead belong in https://httpwg.org/http-core/ to move some of the existing guidance to be HTTP version-independent?

(@royfielding)

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/3408