Re: [libmicrohttpd] Change reason phrase

[Evgeny Grin]

From the new RFC 9112.
https://www.rfc-editor.org/rfc/rfc9112.html#section-4
------------------------------------------------------
A client SHOULD ignore the reason-phrase content because it is not a 
reliable channel for information (it might be translated for a given 
locale, overwritten by intermediaries, or discarded when the message is 
forwarded via other versions of HTTP).
------------------------------------------------------
So unless you are communicating only within a closed network, you cannot 
be sure that "reason-phrase" will be delivered.

HTTP is quite flexible, so you could deliver the same message via 
special header or within the body (context) or your reply.
The simplest way is use special header, like
Unauthorized-Reason: Account frozen

This is very simple, supported by HTTP, reliable and could be easily 
implemented with current MHD API.

--
Evgeny

On 06.12.2022 8:52, Christian Grothoff wrote:
> Well, the RFC says that the client SHOULD ignore it. Yes, the server MAY 
> change it, but to rely on it doesn't create a robust protocol: For 
> example, by my reading, HTTP (reverse) proxies between client and server 
> MAY change the message...
>
> So yes, having the 'wrong' message technically doesn't break the 
> standard, but using the message to convey significant information does.
>
> On 12/6/22 05:24, Tiaan via libmicrohttpd wrote:
> > Thank you, importantly you've answered my question that it is not 
> > possible.
> > May I complete the record then and respectfully disagree with your
> > assessment of the merit. I quote from RFC7231:
> >
> > 6.1 <https://www.rfc-editor.org/rfc/rfc7231#section-6.1>.  Overview of
> > Status Codes
> >
> >     The status codes listed below are defined in this specification,
> >     Section 4 of [RFC7232]
> > <https://www.rfc-editor.org/rfc/rfc7232#section-4>, Section 4 of
> > [RFC7233] <https://www.rfc-editor.org/rfc/rfc7233#section-4>, and
> > Section 3 of
> >     [RFC7235] <https://www.rfc-editor.org/rfc/rfc7235#section-3>.  The
> > reason phrases listed here are only recommendations
> >     -- they can be replaced by local equivalents without affecting the
> >     protocol.
> >
> >
> > and from 7230:
> >
> > The reason-phrase element exists for the sole purpose of providing a
> >     textual description associated with the numeric status code, mostly
> >     out of deference to earlier Internet application protocols that were
> >     more frequently used with interactive text clients.  A client SHOULD
> >     ignore the reason-phrase content.
> >
> >       reason-phrase  = *( HTAB / SP / VCHAR / obs-text )
> >
> >
> > Regards
> >
> >
> > > Only by changing the source code and recompiling MHD. But you should not
> > > do this, this is a very bad idea. You should stick to the standard
> > > messages of the HTTP protocol. If you need to convey additional
> > > information, do it in the body or in a header; try to use HTTP status
> > > codes narrowly to what the HTTP standard says they are for.
> >
> > > On 12/5/22 10:26, Tiaan via libmicrohttpd wrote:
> > > > Hi, is it possible to change the reason phrase of responses e.g. 
> > > > instead
> > of
> > > > HTTP/1.1 401 Unauthorized rather HTTP/1.1 401 Account frozen?

OpenPGP_0x460A317C3326D2AE.asc
Description: OpenPGP public key

OpenPGP_signature
Description: OpenPGP digital signature