    Internet Engineering Task Force (IETF)                     S. Hollenbeck
    Request for Comments: 8521                                 Verisign Labs
    BCP: 221                                                       A. Newton
    Updates: 7484                                                       ARIN
    Category: Best Current Practice                            November 2018
    ISSN: 2070-1721

            Registration Data Access Protocol (RDAP) Object Tagging

    Abstract

       The Registration Data Access Protocol (RDAP) includes a method that
       can be used to identify the authoritative server for processing
       domain name, IP address, and autonomous system number queries.  The
       method does not describe how to identify the authoritative server for
       processing other RDAP query types, such as entity queries.  This
       limitation exists because the identifiers associated with these query
       types are typically unstructured.  This document updates RFC 7484 by
       describing an operational practice that can be used to add structure
       to RDAP identifiers and that makes it possible to identify the
       authoritative server for additional RDAP queries.

    Status of This Memo

       This memo documents an Internet Best Current Practice.

       This document is a product of the Internet Engineering Task Force
       (IETF).  It represents the consensus of the IETF community.  It has
       received public review and has been approved for publication by the
       Internet Engineering Steering Group (IESG).  Further information on
       BCPs is available in Section 2 of RFC 7841.

       Information about the current status of this document, any errata,
       and how to provide feedback on it may be obtained at
       https://www.rfc-editor.org/info/rfc8521.

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    Copyright Notice

       Copyright (c) 2018 IETF Trust and the persons identified as the
       document authors.  All rights reserved.

       This document is subject to BCP 78 and the IETF Trust's Legal
       Provisions Relating to IETF Documents
       (https://trustee.ietf.org/license-info) in effect on the date of
       publication of this document.  Please review these documents
       carefully, as they describe your rights and restrictions with respect
       to this document.  Code Components extracted from this document must
       include Simplified BSD License text as described in Section 4.e of
       the Trust Legal Provisions and are provided without warranty as
       described in the Simplified BSD License.

    Table of Contents

       1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.  Object Naming Practice  . . . . . . . . . . . . . . . . . . .   3
       3.  Bootstrap Service Registry for Provider Object Tags . . . . .   9
         3.1.  Registration Procedure  . . . . . . . . . . . . . . . . .  10
       4.  RDAP Conformance  . . . . . . . . . . . . . . . . . . . . . .  10
       5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
         5.1.  Bootstrap Service Registry Structure  . . . . . . . . . .  11
         5.2.  RDAP Extensions Registry  . . . . . . . . . . . . . . . .  11
       6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
       7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
         7.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
         7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
       Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  13
       Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

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    1.  Introduction

       The Registration Data Access Protocol (RDAP) includes a method
       [RFC7484] that can be used to identify the authoritative server for
       processing domain name, IP address, and Autonomous System Number
       (ASN) queries.  This method works because each of these data elements
       is structured in a way that facilitates automated parsing of the
       element and association of the data element with a particular RDAP
       service provider.  For example, domain names include labels (such as
       "com", "net", and "org") that are associated with specific service
       providers.

       As noted in Section 9 of RFC 7484 [RFC7484], the method does not
       describe how to identify the authoritative server for processing
       entity queries, name server queries, help queries, or queries using
       certain search patterns.  This limitation exists because the
       identifiers bound to these queries are typically not structured in a
       way that makes it easy to associate an identifier with a specific
       service provider.  This document describes an operational practice
       that can be used to add structure to RDAP identifiers and makes it
       possible to identify the authoritative server for additional RDAP
       queries.

       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.

    2.  Object Naming Practice

       Tagging object identifiers with a service provider tag makes it
       possible to identify the authoritative server for processing an RDAP
       query using the method described in RFC 7484 [RFC7484].  A service
       provider tag is constructed by prepending the Unicode HYPHEN-MINUS
       character "-" (U+002D, described as an "unreserved" character in RFC
       3986 [RFC3986]) to an IANA-registered value that represents the
       service provider.  For example, a tag for a service provider
       identified by the string value "ARIN" is represented as "-ARIN".

       In combination with the rdapConformance attribute described in
       Section 4, service provider tags are concatenated to the end of RDAP
       query object identifiers to unambiguously identify the authoritative
       server for processing an RDAP query.  Building on the example from
       Section 3.1.5 of RFC 7482 [RFC7482], an RDAP entity handle can be
       constructed to allow an RDAP client to bootstrap an entity query.

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       The following identifier is used to find information for the entity
       associated with handle "XXXX" at service provider "ARIN":

          XXXX-ARIN

       Clients that wish to bootstrap an entity query can parse this
       identifier into distinct handle and service provider identifier
       elements.  Handles can themselves contain HYPHEN-MINUS characters;
       the service provider identifier is found following the last HYPHEN-
       MINUS character in the tagged identifier.  The service provider
       identifier is used to retrieve a base RDAP URL from an IANA registry.
       The base URL and entity handle are then used to form a complete RDAP
       query path segment.  For example, if the base RDAP URL
       "https://example.com/rdap/" is associated with service provider
       "YYYY" in an IANA registry, an RDAP client will parse a tagged entity
       identifier "XXXX-YYYY" into distinct handle ("XXXX") and service
       provider ("YYYY") identifiers.  The service provider identifier
       "YYYY" is used to query an IANA registry to retrieve the base RDAP
       URL "https://example.com/rdap/".  The RDAP query URL is formed using
       the base RDAP URL and entity path segment described in Section 3.1.5
       of RFC 7482 [RFC7482] and using "XXXX-YYY" as the value of the handle
       identifier.  The complete RDAP query URL becomes
       "https://example.com/rdap/entity/XXXX-YYYY".

       Implementation of this practice requires tagging of unstructured
       potential query identifiers in RDAP responses.  Consider these elided
       examples ("..." is used to note elided response objects) from
       Section 5.3 of RFC 7483 [RFC7483] in which the handle identifiers
       have been tagged with service provider tags "RIR", "DNR", and "ABC",
       respectively:

       {
         "objectClassName" : "domain",
         "handle" : "XXXX-RIR",
         "ldhName" : "0.2.192.in-addr.arpa",
         "nameservers" :
         [
           ...
         ],
         "secureDNS":
         {
           ...
         },
         "remarks" :
         [
           ...
         ],
         "links" :

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         [
           ...
         ],
         "events" :
         [
           ...
         ],
         "entities" :
         [
           {
             "objectClassName" : "entity",
             "handle" : "XXXX-RIR",
             "vcardArray":
             [
               ...
             ],
             "roles" : [ "registrant" ],
             "remarks" :
             [
               ...
             ],
             "links" :
             [
               ...
             ],
             "events" :
             [
               ...
             ]
           }
         ],
         "network" :
         {
           "objectClassName" : "ip network",
           "handle" : "XXXX-RIR",
           "startAddress" : "192.0.2.0",
           "endAddress" : "192.0.2.255",
           "ipVersion" : "v4",
           "name": "NET-RTR-1",
           "type" : "DIRECT ALLOCATION",
           "country" : "AU",
           "parentHandle" : "YYYY-RIR",
           "status" : [ "active" ]
         }
       }

                                     Figure 1

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       {
         "objectClassName" : "domain",
         "handle" : "XXXX-YYY-DNR",
         "ldhName" : "xn--fo-5ja.example",
         "unicodeName" : "foo.example",
         "variants" :
         [
           ...
         ],
         "status" : [ "locked", "transfer prohibited" ],
         "publicIds":
         [
           ...
         ],
         "nameservers" :
         [
           {
             "objectClassName" : "nameserver",
             "handle" : "XXXX-DNR",
             "ldhName" : "ns1.example.com",
             "status" : [ "active" ],
             "ipAddresses" :
             {
               ...
             },
             "remarks" :
             [
               ...
             ],
             "links" :
             [
               ...
             ],
             "events" :
             [
               ...
             ]
           },
           {
             "objectClassName" : "nameserver",
             "handle" : "XXXX-DNR",
             "ldhName" : "ns2.example.com",
             "status" : [ "active" ],
             "ipAddresses" :
             {
               ...
             },
             "remarks" :

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             [
               ...
             ],
             "links" :
             [
               ...
             ],
             "events" :
             [
               ...
             ]
           }
          ],
          "secureDNS":
          {
            ...
          },
          "remarks" :
          [
            ...
          ],
          "links" :
          [
            ...
          ],
          "port43" : "whois.example.net",
          "events" :
          [
            ...
          ],
          "entities" :
          [
            {
              "objectClassName" : "entity",
              "handle" : "XXXX-ABC",
              "vcardArray":
              [
                ...
              ],
              "status" : [ "validated", "locked" ],
              "roles" : [ "registrant" ],
              "remarks" :
              [
                ...
              ],
              "links" :
              [
                ...

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              ],
              "events" :
              [
                ...
              ]
            }
          ]
       }

                                     Figure 2

       As described in Section 5 of RFC 7483 [RFC7483], RDAP responses can
       contain "self" links.  Service provider tags and self references
       SHOULD be consistent.  If they are inconsistent, the service provider
       tag is processed with higher priority when using these values to
       identify a service provider.

       There is a risk of unpredictable processing behavior if the HYPHEN-
       MINUS character is used for naturally occurring, non-separator
       purposes in an entity handle.  This could lead to a client mistakenly
       assuming that a HYPHEN-MINUS character represents a separator and
       that the text that follows HYPHEN-MINUS is a service provider
       identifier.  A client that queries the IANA registry for what they
       assume is a valid service provider will likely receive an unexpected,
       invalid result.  As a consequence, use of the HYPHEN-MINUS character
       as a service provider tag separator MUST be noted by adding an
       rdapConformance value to query responses as described in Section 4.

       The HYPHEN-MINUS character was chosen as a separator for two reasons:
       1) it is a familiar separator character in operational use, and 2) it
       avoids collision with URI-reserved characters.  The list of
       unreserved characters specified in Section 2.3 of RFC 3986 [RFC3986]
       provided multiple options for consideration:

          unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"

       ALPHA and DIGIT characters were excluded because they are commonly
       used in entity handles for non-separator purposes.  HYPHEN-MINUS is
       commonly used as a separator, and recognition of this practice will
       reduce implementation requirements and operational risk.  The
       remaining characters were excluded because they are not broadly used
       as separators in entity handles.

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    3.  Bootstrap Service Registry for Provider Object Tags

       The bootstrap service registry for the RDAP service provider space is
       represented using the structure specified in Section 3 of RFC 7484
       [RFC7484].  The JSON output of this registry contains contact
       information for the registered service provider identifiers,
       alphanumeric identifiers that identify RDAP service providers, and
       base RDAP service URLs as shown in this example.

    {
      "version": "1.0",
      "publication": "YYYY-MM-DDTHH:MM:SSZ",
      "description": "RDAP bootstrap file for service provider object tags",
      "services": [
        [
          ["contact@example.com"],
          ["YYYY"],
          [
            "https://example.com/rdap/"
          ]
        ],
        [
          ["contact@example.org"],
          ["ZZ54"],
          [
            "http://rdap.example.org/"
          ]
        ],
        [
          ["contact@example.net"],
          ["1754"],
          [
            "https://example.net/rdap/",
            "http://example.net/rdap/"
          ]
        ]
      ]
     }

                                     Figure 3

       Alphanumeric service provider identifiers conform to the suffix
       portion ("\w{1,8}") of the "roidType" syntax specified in Section 4.2
       of RFC 5730 [RFC5730].

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    3.1.  Registration Procedure

       The service provider registry is populated using the "First Come
       First Served" policy defined in RFC 8126 [RFC8126].  Provider
       identifier values can be derived and assigned by IANA on request.
       Registration requests include an email address to be associated with
       the registered service provider identifier, the requested service
       provider identifier (or an indication that IANA should assign an
       identifier), and one or more base RDAP URLs to be associated with the
       service provider identifier.

    4.  RDAP Conformance

       RDAP responses that contain values described in this document MUST
       indicate conformance with this specification by including an
       rdapConformance [RFC7483] value of "rdap_objectTag_level_0".  The
       information needed to register this value in the "RDAP Extensions"
       registry is described in Section 5.2.

       The following is an example rdapConformance structure with the
       extension specified.

                 "rdapConformance" :
                 [
                   "rdap_level_0",
                   "rdap_objectTag_level_0"
                 ]

                                     Figure 4

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    5.  IANA Considerations

       IANA has created the RDAP "Bootstrap Service Registry for Provider
       Object Tags" listed below and made it available as a JSON object.
       The contents of this registry are described in Section 3; the formal
       syntax is specified in Section 10 of RFC 7484 [RFC7484].

    5.1.  Bootstrap Service Registry Structure

       Entries in this registry contain the following information:

       o  an email address that identifies a contact associated with the
          registered RDAP service provider value.
       o  an alphanumeric value that identifies the RDAP service provider
          being registered.
       o  one or more URLs that provide the RDAP service regarding this
          registration.  The URLs are expected to supply the same data, but
          they can differ in scheme or other components as required by the
          service operator.

    5.2.  RDAP Extensions Registry

       IANA has registered the following value in the "RDAP Extensions"
       registry:

          Extension identifier: rdap_objectTag
          Registry operator: Any
          Published specification: This document
          Contact: IESG <iesg@ietf.org>

          Intended usage: This extension describes a best practice for
          structuring entity identifiers to enable query bootstrapping.

    6.  Security Considerations

       This practice uses IANA as a well-known, centrally trusted authority
       to allow users to get RDAP data from an authoritative source, which
       reduces the risk of sending queries to non-authoritative sources and
       divulging query information to unintended parties.  Using TLS 1.2
       [RFC5246] or TLS 1.3 [RFC8446], which obsoletes TLS 1.2, to protect
       the connection to IANA allows the server to authenticate itself as
       being operated by IANA and provides integrity protection for the
       resulting referral information, as well as provides privacy
       protection via data confidentiality.  The subsequent RDAP connection
       is performed as usual and retains the same security properties of the
       RDAP protocols themselves as described in RFC 7481 [RFC7481].

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    7.  References

    7.1.  Normative References

       [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119,
                  DOI 10.17487/RFC2119, March 1997,
                  <https://www.rfc-editor.org/info/rfc2119>.

       [RFC5730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
                  STD 69, RFC 5730, DOI 10.17487/RFC5730, August 2009,
                  <https://www.rfc-editor.org/info/rfc5730>.

       [RFC7484]  Blanchet, M., "Finding the Authoritative Registration Data
                  (RDAP) Service", RFC 7484, DOI 10.17487/RFC7484, March
                  2015, <https://www.rfc-editor.org/info/rfc7484>.

       [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
                  Writing an IANA Considerations Section in RFCs", BCP 26,
                  RFC 8126, DOI 10.17487/RFC8126, June 2017,
                  <https://www.rfc-editor.org/info/rfc8126>.

       [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
                  2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
                  May 2017, <https://www.rfc-editor.org/info/rfc8174>.

    7.2.  Informative References

       [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
                  Resource Identifier (URI): Generic Syntax", STD 66,
                  RFC 3986, DOI 10.17487/RFC3986, January 2005,
                  <https://www.rfc-editor.org/info/rfc3986>.

       [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
                  (TLS) Protocol Version 1.2", RFC 5246,
                  DOI 10.17487/RFC5246, August 2008,
                  <https://www.rfc-editor.org/info/rfc5246>.

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

       [RFC7482]  Newton, A. and S. Hollenbeck, "Registration Data Access
                  Protocol (RDAP) Query Format", RFC 7482,
                  DOI 10.17487/RFC7482, March 2015,
                  <https://www.rfc-editor.org/info/rfc7482>.

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    RFC 8521                   RDAP Object Tagging             November 2018

       [RFC7483]  Newton, A. and S. Hollenbeck, "JSON Responses for the
                  Registration Data Access Protocol (RDAP)", RFC 7483,
                  DOI 10.17487/RFC7483, March 2015,
                  <https://www.rfc-editor.org/info/rfc7483>.

       [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
                  Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
                  <https://www.rfc-editor.org/info/rfc8446>.

    Acknowledgements

       The authors would like to acknowledge the following individuals for
       their contributions to the development of this document: Tom
       Harrison, Patrick Mevzek, and Marcos Sanz.  In addition, the authors
       would like to recognize the Regional Internet Registry (RIR)
       operators (AFRINIC, APNIC, ARIN, LACNIC, and RIPE) that have been
       implementing and using the practice of tagging handle identifiers for
       several years.  Their experience provided significant inspiration for
       the development of this document.

    Authors' Addresses

       Scott Hollenbeck
       Verisign Labs
       12061 Bluemont Way
       Reston, VA  20190
       United States of America

       Email: shollenbeck@verisign.com
       URI:   http://www.verisignlabs.com/

       Andrew Lee Newton
       American Registry for Internet Numbers
       PO Box 232290
       Centreville, VA  20120
       United States of America

       Email: andy@arin.net
       URI:   http://www.arin.net

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