| Internet-Draft | Use of EAI in EPP | June 2022 |
| Belyavskiy & Gould | Expires 10 December 2022 | [Page] |
This document describes an EPP extension that permits usage of Internationalized Email Addresses in the EPP protocol and specifies the terms when it can be used by EPP clients and servers. The Extensible Provisioning Protocol (EPP), being developed before the standards for Internationalized Email Addresses (EAI), does not support such email addresses.¶
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[RFC6530] introduced the framework for Internationalized Email Addresses. To make such addresses more widely accepted, the changes to various protocols need to be introduced.¶
This document describes an Extensible Provisioning Protocol (EPP) extension that permits usage of Internationalized Email Addresses in the EPP protocol and specifies the terms when it can be used by EPP clients and servers. A new form of EPP extension, referred to as a Functional Extension, is defined and used to apply the rules for the handling of email address elements in all of the [RFC5730] extensions negotiated in the EPP session, which include the object and command-responses extensions. The described mechanism can be applied to any object or command-response extension that uses an email address.¶
The Extensible Provisioning Protocol (EPP) specified in [RFC5730] is a base document for object management operations and an extensible framework that maps protocol operations to objects. The specifics of various objects managed via EPP is described in separate documents. This document is only referring to an email address as a property of a managed object, such as the <contact:email> element in the EPP contact mapping [RFC5733] or the <org:email> element in the EPP organization mapping [RFC8543], and command-response extensions applied to a managed object.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
Servers that implement this extension SHOULD provide a way for clients to progressively update their implementations when a new version of the extension is deployed. A newer version of the extension is expected to use an XML namespace with a higher version number than the prior versions.¶
Support of non-ASCII email address syntax is defined in RFC 6530 [RFC6530]. This mapping does not prescribe minimum or maximum lengths for character strings used to represent email addresses. The exact syntax of such addresses is described in Section 3.3 of [RFC6531]. The validation rules introduced in RFC 6531 MUST be followed when processing this extension.¶
The definition of email address in the EPP RFCs, including Section 2.6 of [RFC5733] and Section 4.1.2, 4.2.1, and 4.2.5 of [RFC8543], references [RFC5322] for the email address syntax. The XML schema definition in Section 4 of [RFC5733] and Section 5 of [RFC8543] defines the "email" element using the type "eppcom:minTokenType", which is defined in Section 4.2 of [RFC5730] as an XML schema "token" type with minimal length of one. The XML schema "token" type will fully support the use of EAI addresses, so the primary application of the EAI extension is to apply the use of [RFC6531] instead of [RFC5322] for the email address syntax. Other EPP extensions may follow the formal syntax definition using the XML schema type "eppcom:minTokenType" and the [RFC5322] format specification, where this extension applies to all EPP extensions with the same or similar definitions.¶
The email address format is formally defined in Section 3.4.1 of [RFC5322], which only consists of printable US-ASCII characters for both the local-part and the domain ABNF rules. [RFC6531] extends the Mailbox, Local-part and Domain ABNF rules in [RFC5321] to support "UTF8-non-ascii", defined in Section 3.1 of [RFC6532], for the local-part and U-label, defined in Section 2.3.2.1 of [RFC5890], for the domain. By applying the syntax rules of [RFC6531], the EPP extensions will change from supporting only ASCII characters to supporting Internationalized characters both in the email address local-part and domain-part.¶
[RFC5730] defines three types of extensions at the protocol, object, and command-response level, which impact the structure of the EPP messages. A Functional Extension applies a functional capability to an existing set of EPP extensions and properties. The scope of the applicable EPP extensions and applicable extension properties are defined in the Functional Extension along with the requirements for the servers and clients that support it. The Functional Extension needs to cover the expected behavior of the supporting client or server when interacting with an unsupporting client or server. Negotiating support for a Functional Extension is handled using the EPP Greeting and EPP Login services.¶
The functional extension applies to all object extensions and command-response extensions negotiated in the EPP session that include email address properties. Examples include the <contact:email> element in the EPP contact mapping [RFC5733] or the <org:email> element in the EPP organization mapping [RFC8543]. All registry zones (e.g., top-level domains) authorized for the client in the EPP session apply. There is no concept of a per-client, per-zone, per-extension, or per-field setting that is used to indicate support for EAI, but instead it's a global setting that applies to the EPP session.¶
The client and the server can signal support for the functional extension using a namespace URI in the login and greeting extension services respectively. The namespace URI "urn:ietf:params:xml:ns:epp:eai-1.0" is used to signal support for the functional extension. The client includes the namespace URI in an <svcExtension> <extURI> element of the [RFC5730] <login> Command. The server includes the namespace URI in an <svcExtension> <extURI> element of the [RFC5730] Greeting.¶
If both client and server have indicated the support of the EAI addresses during the session establishment, it implies the possibility to process the EAI address in any message having an email property during the established EPP session. Below are the server and client obligations when the EAI extension has been successfuly negotiated in the EPP session.¶
The server MUST satisfy the following obligations when the EAI extension has been negotiated:¶
The client MUST satisfy the following obligations when THE EAI extension has been negotiated:¶
The lack of EAI support can cause data and functional issues, so an EAI supporting client or server needs to handle cases where the opposite party doesn't support EAI. Below are the server and client obligations when the EAI extension is not negotiated due to the lack of support by the peer.¶
The EAI supporting server MUST satisfy the following obligations when the client does not support the EAI extension:¶
The EAI supporting client MUST satisfy the following obligations when the server does not support the EAI extension:¶
This document uses URNs to describe XML namespaces and XML schemas conforming to a registry mechanism described in RFC 3688 [RFC3688]. The following URI assignment should be made by IANA:¶
Registration request for the eai namespace:¶
URI: urn:ietf:params:xml:ns:epp:eai-1.0 Registrant Contact: IESG XML: None. Namespace URIs do not represent an XML specification.¶
The EPP extension described in this document should be registered by IANA in the "Extensions for the Extensible Provisioning Protocol (EPP)" registry described in RFC 7451 [RFC7451]. The details of the registration are as follows:¶
Name of Extension: Use of Internationalized Email Addresses
in EPP protocol
Document status: Standards Track
Reference: TBA
Registrant Name and Email Address: IESG, <iesg@ietf.org>
Top-Level Domains(TLDs): Any
IPR Disclosure: None
Status: Active
Notes: None
¶
Note to RFC Editor: Please remove this section and the reference to RFC 7942 [RFC7942] before publication.¶
This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in RFC 7942 [RFC7942]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.¶
According to RFC 7942 [RFC7942], "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".¶
Organization: Verisign Inc.¶
Name: Verisign EPP SDK¶
Description: The Verisign EPP SDK includes both a full client implementation and a full server stub implementation of draft-ietf-regext-epp-eai.¶
Level of maturity: Development¶
Coverage: All aspects of the protocol are implemented.¶
Licensing: GNU Lesser General Public License¶
Contact: jgould@verisign.com¶
URL: https://www.verisign.com/en_US/channel-resources/domain-registry-products/epp-sdks¶
The extended security considerations discussion in [RFC6530] and [RFC6531] applies here.¶
As email address is often a primary end user contact, an invalid email address may put the communication with the end user into risk in case when such contact is necessary. In case of an invalid domain name in the email address a malicious actor can register a valid domain name with similar U-label (homograph attack) and get a control over the domain name associated with the contact using social engineering techniques. To reduce the risk of the use of invalid domain names in email addresses, registries SHOULD validate the domain name syntax in the provided email addresses and validate all code points in the domain name according to IDNA2008 [RFC5892].¶
The authors would like to thank Alexander Mayrhofer, Gustavo Lozano, Jody Kolker, John C Klensin, John Levine, Klaus Malorny, Marco Schrieck, Mario Loffredo, Murray S. Kucherawy, Patrick Mevzek, Pete Resnick, Scott Hollenbeck, Taras Heichenko, and Thomas Corte for their careful review and valuable comments.¶