Re: Pseudo Headers in Binary Representation of HTTP Messages (RFC 9292)

I find the second way you wrote it clearer, Lucas. In hyper, we forbid
colons in generic header names, and treat pseudo-fields specially.

On Thu, Jul 6, 2023, 11:28 AM Lucas Pardue <lucaspardue.24.7@gmail.com>
wrote:

> Hi Norman,
>
>
> On Thu, Jul 6, 2023 at 4:03 PM Norman Maurer <norman_maurer@apple..com>
> wrote:
>
>> Hi all,
>>
>> I have a question related to pseudo headers and binary http.
>>
>> https://www.rfc-editor.org/rfc/rfc9292.html#section-3.6
>>
>> Here it says:
>>
>> ----
>> For field names, byte values that are not permitted in an HTTP field name
>> cause the message to be invalid; see Section 5.1 of [HTTP] for a definition
>> of what is valid and Section 4 regarding the handling of invalid messages.
>> A recipient MUST treat a message that contains field values that would
>> cause an HTTP/2 message to be malformed according to Section 8.2.1 of
>> [HTTP/2] as invalid; see Section 4.
>> ----
>>
>> And later on:
>> ----
>> Other pseudo-fields that are defined by protocol extensions MAY be
>> included; pseudo-fields cannot be included in trailers (see Section 8.1 of
>> [HTTP/2]). A Field Line containing pseudo-fields MUST precede other Field
>> Line values. A message that contains a pseudo-field after any other field
>> is invalid; see Section 4.
>> ----
>>
>> This is a bit confusing to me as if I follow the first paragraph it seems
>> like it wouldnt be allowed to use “ANY” pseudo-headers as “:” is not a
>> valid char in header names for HTTP.
>>
>>
> I agree this text has the potential for confusion. It doesn't help that
> RFC 9292 uses the term "pseudo-field" when RFC 9113 uses consistently only
> pseudo-header field
>
> The intent of RFC 9292 seems to be to allow other pseudo-header fields in
> the messages. One way to read this is that a psuedo-header field name !=
> HTTP field name (see https://www.rfc-editor.org/rfc/rfc9113#section-8.3)
> and therefore the rules can be bent a bit to allow the colon. However, this
> seems a bit of a stretch. It might be clearer to state that a Field Line
> can either represent an HTTP field or a pseudo-header field, and that only
> the first byte of the Name field may contain a : character (ASCII 0x3a)
> that identifies the type.
>
> Cheers
> Lucas
>
>