RFC Errata
RFC 6376, "DomainKeys Identified Mail (DKIM) Signatures", September 2011
Source of RFC: dkim (art)See Also: RFC 6376 w/ inline errata
Errata ID: 5070
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Chris Newman
Date Reported: 2017-07-15
Verifier Name: Barry Leiba
Date Verified: 2019-04-30
Section 3.2 says:
tag-spec = [FWS] tag-name [FWS] "=" [FWS] tag-value [FWS] tag-name = ALPHA *ALNUMPUNC tag-value = [ tval *( 1*(WSP / FWS) tval ) ] ; Prohibits WSP and FWS at beginning and end
It should say:
tag-spec = [FWS] tag-name [FWS] "=" [FWS] [tag-value [FWS]] tag-name = ALPHA *ALNUMPUNC tag-value = tval *( 1*(WSP / FWS) tval ) ; Prohibits WSP and FWS at beginning and end
Notes:
The ABNF in the document permits two FWS rules to appear in the row. This results in permitting a line with only whitespace in the header which falls into obsolete syntax in RFC 5322 (Appendix B rule 12). The corrected text disallows this by eliding the second FWS when the tag-value is empty/omitted.