RFC 7622, "Extensible Messaging and Presence Protocol (XMPP): Address Format", September 2015Source of RFC: xmpp (art)
Errata ID: 5769
Status: Held for Document Update
Publication Format(s) : TEXT
Reported By: Florian Schmaus
Date Reported: 2019-06-30
Held for Document Update by: Barry Leiba
Date Held: 2019-07-02
Section 3.2.1 says:
An entity that prepares a string for inclusion in an XMPP domainpart slot MUST ensure that the string consists only of Unicode code points that are allowed in NR-LDH labels or U-labels as defined in [RFC5890].
It should say:
An entity that prepares a string for inclusion in an XMPP domainpart slot MUST ensure that the string consists only of Unicode code points that are allowed in NR-LDH labels or U-labels as defined in [RFC5890], or the DNS label separator "dot" (U+002E, FULL STOP).
The current specification forbids the inclusion of dots (".") in the domainpart, since they are not allowed in NR-LDH nor U-labels. But they should be allowed, as otherwise a DNS name could never be put into an XMPP domainpart (which is commonly done).
----- Verifier notes -----
This is correct as far as it goes, but there's more to the fix than this, so proper discussion, consensus, and document update are needed. There are, for example, other dot characters that need to be allowed as well as U+002E. The bottom line is that Florian is correct that DNS label separators need to be allowed, and the proper fix to the text is deferred to any future document update.