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Erratum 5918: Header Field name length limit #36

Closed ietf-svn-bot closed 3 years ago

ietf-svn-bot commented 3 years ago

owner:resnick@episteme.net resolution_fixed type_defect | by alexey.melnikov@isode.com

Section 2.2 says:

Header fields are lines beginning with a field name, followed by a colon (":"), followed by a field body, and terminated by CRLF. A field name MUST be composed of printable US-ASCII characters (i.e., characters that have values between 33 and 126, inclusive), except colon.

Notes from Marcus Bointon:

I'm reporting an omission rather than a correction. The description of field names in S2.2 does not describe any length limit, but it implicitly prohibits folding by not permitting WSP chars in the name. 3.6.8 defines an ABNF for field-name, but does not specify a length limit either.

As far as I can see this means that field names should be limited to 77 characters – the field name and a trailing : – after which the field body can start after FWS on the next line.

I suspect this will be open to some debate, so I'm not sure what to suggest as a correction beyond that. Nor do I know whether common clients & servers impose their own arbitrary limits on field names.

Issue migrated from trac:36 at 2022-01-31 12:36:34 +0000

ietf-svn-bot commented 3 years ago

@alexey.melnikov@isode.com commented

As per the online meeting feedback (to be verified on the mailing list):

Add ABNF comment based on Ned Freed's proposal:

You can’t fold a header field name, so the effect is you SHOULD limit things to 78 characters including the colon.

ietf-svn-bot commented 3 years ago

@alexey.melnikov@isode.com commented

Based on the mailing list discussion and discussion during the virtual Bangkok IETF 109, there is rough consensus to add an ABNF comment pointing out that due to the line length limit of 78 octets (including the ":") the header field length limit is 77 octets.

ietf-svn-bot commented 3 years ago

@alexey.melnikov@isode.com commented

ABNF comment added in draft-ietf-emailcore-rfc5322bis-01

ietf-svn-bot commented 3 years ago

@alexey.melnikov@isode.com changed status from new to closed

ietf-svn-bot commented 3 years ago

@alexey.melnikov@isode.com set resolution to fixed