



Registration Protocols Extensions (regext)                      G. Brown
Internet-Draft                                                 A. Newton
Intended status: Standards Track                                   ICANN
Expires: 19 June 2026                                   16 December 2025


                        Efficient RDAP Referrals
                  draft-ietf-regext-rdap-referrals-01

Abstract

   This document describes an RDAP extension that allows RDAP clients to
   request to be referred to a related RDAP record for a resource.

Status of This Memo

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   This Internet-Draft will expire on 19 June 2026.

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   provided without warranty as described in the Revised BSD License.







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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  RDAP Referral Request . . . . . . . . . . . . . . . . . . . .   3
   3.  RDAP Referral Response  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Selecting The Appropriate Link  . . . . . . . . . . . . .   4
     3.2.  Caching by Intermediaries . . . . . . . . . . . . . . . .   5
   4.  RDAP Conformance  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Changes from 00 to 01 . . . . . . . . . . . . . . . . . .   5
     6.2.  Changes from draft-brown-rdap-referrals-02 to
           draft-ietf-regext-rdap-referrals-00 . . . . . . . . . . .   5
     6.3.  Changes from 01 to 02 . . . . . . . . . . . . . . . . . .   6
     6.4.  Changes from 00 to 01 . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Many Registration Data Access Protocol (RDAP, described in [RFC7480],
   [RFC7481], [RFC9082], [RFC9083] and others) resources contain links
   to related RDAP resources.

   For example, in the domain space, an RDAP record for a domain name
   received from the registry operator may include a link for the RDAP
   record for the same object provided by the sponsoring registrar,
   while in the IP address space, an RDAP record for an address
   allocation may include links to enclosing or sibling prefixes.

   In both cases, RDAP service users are often equally if not more
   interested in these related RDAP resources than the resource provided
   by the TLD registry or RIR.

   While RDAP supports redirection of RDAP requests using HTTP
   redirections (which use a 3xx HTTP status and the "Location" header
   field, see Section 15.4 of [RFC9110]), it is not possible for RDAP
   servers to know _a priori_ whether a client requesting an RDAP record
   is doing so because it wants to retrieve a related RDAP record, or
   its own, so it can only respond by providing the full RDAP response.
   The client must then parse that response in order to extract the
   relevant URL from the "links" property of the object.

   This results in the wasteful expenditure of time, compute resources
   and bandwidth on the part of both the client and server.






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   This document describes an extension to RDAP that allows clients to
   request that an RDAP server refer them to the URL of a related
   resource.

2.  RDAP Referral Request

   To request a referral to a related resource, the client sends an HTTP
   GET request to the RDAP server with a path of the form:

   /referrals0_ref/<relation>/<lookup path>

   The client replaces <lookup path> with the lookup path of the object
   being sought and the <relation> with the desired relationship type.
   For example, a referral query for the domain example.com would be:

   /referrals0_ref/related/domain/example.com

   The referral query for the parent network of 192.0.2.42 would have
   the following full path:

   /referrals0_ref/rdap-up/ip/192.0.2.42

   Lookup paths for domain names, IP networks, autonomous system
   numbers, nameservers, and entities are described in [RFC9082].
   Lookups defined by RDAP extensions may also use this extension.

   Referral requests for searches, where more than one object is
   returned, and help queries, as described by [RFC9083], are not
   supported.  Servers MUST return an HTTP 400 for these requests.

3.  RDAP Referral Response

   If the object specified in the request exists, a single appropriate
   link exists, and the client is authorised to perform the request, the
   server response MUST have an HTTP status code of 301 or 302, and
   include an HTTP Location header field, whose value contains the URL
   of the linked resource.

   When an RDAP server holds in its datastore more than one relationship
   type for an object, a scenario that is possible but not common, only
   one of the URLs can be returned, as determined by server policy.

   The following examples use the HTTP/1.1 message exchange syntax as
   seen in [RFC9110].

   An example of a referral request from a domain registry to a domain
   registrar:




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   Client Request:

   GET /referrals0_ref/related/domain/example.com HTTP/1.1
   Accept: application/rdap+json

   Server Response:

   HTTP/1.1 200 OK
   Location: https://registrar.example/domain/example.com

   An example of a referral request for a parent IPv4 network:

   Client Request:

   GET /referrals0_ref/rdap-up/ip/192.0.2.42 HTTP/1.1
   Accept: application/rdap+json

   Server Response:

   HTTP/1.1 200 OK
   Location: https://rir.example/ip/192.0.2.0/24

   An example of a referral request for a parent IPv6 network:

   Client Request:

   GET /referrals0_ref/rdap-up/ip/2001%3adb8%3a%3a1 HTTP/1.1
   Accept: application/rdap+json"

   Server Response:

   HTTP/1.1 200 OK
   Location: https://rir.example/ip/2001%3adb8%3a%3a/32

3.1.  Selecting The Appropriate Link

   When the server receives a referral request, it must select which of
   an object's links it should use to construct the response.

   The rel property of the selected link MUST match <relation> path
   segment of the request.  The type and hreflang properties of the
   link, if present, MUST match the Accept and (if specified) Accept-
   Language header fields of the request.








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3.2.  Caching by Intermediaries

   To facilitate caching of RDAP resources by intermediary proxies,
   servers which provide a referral based on the value of the Accept
   header field in the request MUST include a Vary header field (See
   Section 12.5.5 of [RFC2535]) in the response.  This field MUST
   include accept, and MAY include other header field names.

   Example:

   Vary: accept, accept-language

4.  RDAP Conformance

   Servers which implement this specification MUST include the string
   "referrals0" in the "rdapConformance" array in all RDAP responses.

5.  IANA Considerations

   IANA is requested to register the following value in the RDAP
   Extensions Registry:

   *Extension identifier:* referrals0

   *Registry operator:* any.

   *Published specification:* this document.

   *Contact:* the authors of this document.

   *Intended usage:* this extension allows clients to request to be
   referred to a related resource for an RDAP resource.

6.  Change Log

   This section is to be removed before publishing as an RFC.

6.1.  Changes from 00 to 01

   *  Switch to using a path segment and a 30x redirect.

   *  Describe how the server behaves when multiple links exist.

6.2.  Changes from draft-brown-rdap-referrals-02 to draft-ietf-regext-
      rdap-referrals-00

   *  Nothing apart from the name.




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6.3.  Changes from 01 to 02

   *  add this change log.

6.4.  Changes from 00 to 01

   *  change extension identifer from registrar_link_header to
      referrals0.

7.  Normative References

   [RFC2535]  Eastlake 3rd, D., "Domain Name System Security
              Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999,
              <https://www.rfc-editor.org/info/rfc2535>.

   [RFC7480]  Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 7480, DOI 10.17487/RFC7480, March 2015,
              <https://www.rfc-editor.org/info/rfc7480>.

   [RFC7481]  Hollenbeck, S. and N. Kong, "Security Services for the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 7481, DOI 10.17487/RFC7481, March 2015,
              <https://www.rfc-editor.org/info/rfc7481>.

   [RFC9082]  Hollenbeck, S. and A. Newton, "Registration Data Access
              Protocol (RDAP) Query Format", STD 95, RFC 9082,
              DOI 10.17487/RFC9082, June 2021,
              <https://www.rfc-editor.org/info/rfc9082>.

   [RFC9083]  Hollenbeck, S. and A. Newton, "JSON Responses for the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 9083, DOI 10.17487/RFC9083, June 2021,
              <https://www.rfc-editor.org/info/rfc9083>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.

Authors' Addresses

   Gavin Brown
   ICANN
   12025 Waterfront Drive, Suite 300
   Los Angeles, CA 90292
   United States of America
   Email: gavin.brown@icann.org



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   URI:   https://icann.org


   Andy Newton
   ICANN
   12025 Waterfront Drive, Suite 300
   Los Angeles, CA 90292
   United States of America
   Email: andy.newton@icann.org
   URI:   https://icann.org









































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