Internet Engineering Task Force (IETF) S. Hollenbeck

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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RFC 8521 RDAP Object Tagging November 2018

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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RFC 8521 RDAP Object Tagging November 2018

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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RFC 8521 RDAP Object Tagging November 2018

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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RFC 8521 RDAP Object Tagging November 2018

[
...
],
"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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RFC 8521 RDAP Object Tagging November 2018

{
"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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RFC 8521 RDAP Object Tagging November 2018

[
...
],
"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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RFC 8521 RDAP Object Tagging November 2018

],
"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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RFC 8521 RDAP Object Tagging November 2018

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": [
[
["[email protected]"],
["YYYY"],
[
"https://example.com/rdap/"
]
],
[
["[email protected]"],
["ZZ54"],
[
"http://rdap.example.org/"
]
],
[
["[email protected]"],
["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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RFC 8521 RDAP Object Tagging November 2018

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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RFC 8521 RDAP Object Tagging November 2018

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 <[email protected]>

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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RFC 8521 RDAP Object Tagging November 2018

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: [email protected]
URI: http://www.verisignlabs.com/

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

Email: [email protected]
URI: http://www.arin.net

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