- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Wed, 25 Oct 2017 19:47:31 +0200
- To: David Matson <dmatson@microsoft.com>, RFC Errata System <rfc-editor@rfc-editor.org>, "fielding@gbiv.com" <fielding@gbiv.com>, "ben@nostrum.com" <ben@nostrum.com>, "aamelnikov@fastmail.fm" <aamelnikov@fastmail.fm>, "adam@nostrum.com" <adam@nostrum.com>, "mnot@mnot.net" <mnot@mnot.net>, "pmcmanus@mozilla.com" <pmcmanus@mozilla.com>
- Cc: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
On 2017-10-25 19:31, David Matson wrote: > When generic code does know the ABNF of the header field, is it still allowed to remove spaces in field values before processing/passing downstream? If so, where should this behavior be documented as permissible? (Is this something that each field now needs to document separately?) By my definition, it wouldn't be generic anymore :-)- > (FWIW, the spec doesn't technically use OWS inside field-content; the ABNF between field-vchar is equivalent to RWS, I believe.) OWS appears as part of list productions, see <https://www.greenbytes.de/tech/webdav/rfc7230.html#abnf.extension>. It also appears in specific header fields, such as <https://www.greenbytes.de/tech/webdav/rfc7231.html#media.type>... > For example, if a proxy understands the ABNF of all the following headers and receives a response with Allow, Server, Vary, etc header fields set where there's more than one space separating items in the list, can it still normalize down to one space before passing the response back to the client? The Allow case is perhaps the most interesting - RFC 7231 specifically prohibits modifying the Allow header field, but I suspect the intent there is more around the list of methods rather than the whitespace characters between them. > ... Aha: <https://www.greenbytes.de/tech/webdav/rfc7231.html#rfc.section.7.4.1.p.4>: "A proxy MUST NOT modify the Allow header field — it does not need to understand all of the indicated methods in order to handle them according to the generic message handling rules." I agree with you about the intent, and that modifying OWS here would be harmless. Do we need to state that, and yes, what header fields are affected? Best regards, Julian
Received on Wednesday, 25 October 2017 17:48:32 UTC