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JID Preperation and Validation Service This specification defines a way for an XMPP entity to request another entity to prepare and validate a given JID. &LEGALNOTICE; 0328 Experimental Standards Track Standards XMPP Core XMPP IM XEP-0030 jid-prep Lance Stout lance@lance.im lance@lance.im &flow; 0.2 2019-09-09 fs
  • Do not return error IQ result if the string to validate is not a valid JID. It is indistinguishable if the error is caused by the string to check, or if some other involved JID, like the one in the 'to' attribute, is malformed.
  • Return the normalized JID in its parts, to make it clear which parts constitute the JID
  • Do not use text as child of an IQ child element. Using text makes it impossible to inject further child elements as XMPP disallows mixed content.
  • Add support for base64 encoding.
  • Always announce the jidprep identity.
0.1 2013-05-28 psa

Initial published version approved by the XMPP Council.

0.0.2 2013-05-21 lance

Incorporated feedback.

0.0.1 2013-05-08 lance

Initial version.

To accurately compare and match JIDs, a normalization step is required by &rfc7622;. This normalization is split into two steps called 'Preparation' and 'Enforcement' by &rfc8264; and maybe resource-intensive. The protocol defined herein, called "JID Prep" can be used to ask XMPP entities to perform such a normalization. Amongst other use-cases, this protocol can be used for testing purposes, where a test suite checks the conformance of an normalization implementation of, e.g., an XMPP server implementation.

Furthermore, in some environments, especially ones like IoT where devices with constraint resources are used, a client may not have access to the various Unicode and internationalization libraries necessary to properly normalize a JID. For those situations, this protocol can be used by a client to ask a server to normalize a JID on its behalf.

If a server supports JID Prep queries, it MUST specify the 'urn:xmpp:jidprep:1' feature in its service discovery information features as specified in &xep0030;.

... ]]>

To request preparation and enforcement, and thus normalization and validation, of a string to a JID, the client sends a JID Prep request to the service. This request is an &IQ; of type 'get', containing a <jid-validate-request/> element qualified by the 'urn:xmpp:jidprep:1' namespace. This element contains a <maybe-jid/> child element whose textual content is the string to normalize to and validate as JID.

Σ@example.com/resource ]]>

If the given string can be enforced to a valid JID, then a <jid-validate-result/> with a <valid-jid/> child element is returned. This child element contains the normalized JID parts. The valid-jid element MUST contain <domainpart/> and may contain <localpart/> and/or <resourcepart/> elements. If the JID does not contain a local- or resourcepart, then the corresponding element is omitted. Those elements contain the normalized, i.e., PRECIS enforced, strings of the own JID parts.

σ example.com resource ]]>

If the service is given an invalid JID, a <jid-validate-result/> IQ result response with an <invalid-jid/> elmeent is returned.

henryⅣ@example.com ]]> Invalid codepoint 'Ⅳ' in localpart. ]]>

To be able to feed arbitrary strings into the validator, not being limited by XML 1.0, the protocol supports an optional Base64 encoding of the string to validate. The requestor first encodes the string to UTF-8, then encodes the UTF-8 byte-sequence using Base64 (&rfc4648; § 4) and places the result into an <base64-maybe-jid/> element. This element is a put under the <jid-validate-base64-request/> IQ child element qualified by the 'urn:xmpp:jidprep:1' namespace.

The IQ respones of the service are identical to the ones of the non-Base64 case.

If supported, service announces 'urn:xmpp:jidprep:base64:1' feature.

zqNAZXhhbXBsZS5jb20vcmVzb3VyY2U= ]]>

If a client has the ability to perform the normalization process itself, it SHOULD NOT make use of the protocol defined herein.

Upon a successful response, it is RECOMMENDED that the client caches the result, mapping the original JID to the normalized version.

As the process for normalizing and validating a JID can be resource intensive, there is a possibility for denial of service attacks. A server MAY rate limit the number of requests to prevent such attacks. Likewise, the server MAY restrict access to the service torequests from users that are local to the server or otherwhise trusted.

This document requires no interaction with &IANA;.

The ®ISTRAR; includes 'urn:xmpp:jidprep:1' in its registry of protocol namespaces (see &NAMESPACES;).

  • urn:xmpp:jidprep:1
&NSVER;

TODO: Add once the XEP leaves the experimental state.