Internet Engineering Task Force (IETF)
Request for Comments: 8521
BCP: 221
Updates: 7484
Category: Best Current Practice
ISSN: 2070-1721

S. Hollenbeck
Verisign Labs
A. Newton
ARIN
November 2018

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.

Copyright Notice

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.

   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

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.

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" :
     [
       ...
     ],
     "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

{

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

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].

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

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].

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>.
   
   [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