Registration Data Access Protocol (RDAP) Object Tagging
A hyphen and a short provider tag on the end of an RDAP handle tell clients which server to ask.
Hollenbeck, S. and A. Newton, "Registration Data Access Protocol (RDAP) Object Tagging", BCP 221, RFC 8521, DOI 10.17487/RFC8521, November 2018, <https://www.rfc-editor.org/info/rfc8521>.
@misc{rfc8521,
series = {Request for Comments},
number = 8521,
howpublished = {RFC 8521},
publisher = {RFC Editor},
doi = {10.17487/RFC8521},
url = {https://www.rfc-editor.org/info/rfc8521},
author = {S. Hollenbeck and A. Newton},
title = {{Registration Data Access Protocol (RDAP) Object Tagging}},
pagetotal = 13,
year = 2018,
month = nov,
} RFC text
Contents
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.
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
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
AI ELI5
On this page
§1The Bootstrapping Gap in RDAP
The Registration Data Access Protocol (RDAP) has a method, defined in RFC 7484, for finding the authoritative server that should answer a query. It works for domain names, IP addresses and Autonomous System Numbers (ASNs), because each of these is structured so that it can be tied to one service provider. A domain name, for example, has labels such as com, net and org that belong to specific providers.
The same RFC notes that the method does not cover entity queries, name server queries, help queries or queries using certain search patterns. The identifiers behind those queries are typically unstructured, so nothing in them points to a provider.
RFC 8521 is a Best Current Practice that updates RFC 7484. It describes an operational practice that adds structure to RDAP identifiers so that the authoritative server can be found for these additional queries.
Some lookups, like finding a person's record, do not say which office keeps it. This document adds a label so you know which office to ask.
§2Tagging Object Identifiers
A service provider tag is built by putting the HYPHEN-MINUS character HYPHEN-MINUS (U+002D) in front of an IANA-registered value that stands for the provider. A provider identified as ARIN therefore has the tag -ARIN. The tag is added to the end of an RDAP object identifier, so a handle XXXX at that provider becomes XXXX-ARIN.
Implementing the practice means tagging the unstructured identifiers that appear in RDAP responses. The RFC shows elided response examples in which the handle of a domain, an entity, a nameserver and an IP network carry tags such as -RIR, -DNR and -ABC.
Responses can also contain self links. The tag and the self reference SHOULD be consistent. If they are not, the service provider tag is processed with higher priority when identifying the provider.
The provider's short name is glued onto the end of each ID with a dash, like a name tag that says KID-SCHOOLNAME.
§2How a Client Finds the Server
A client that wants to bootstrap an entity query splits the tagged identifier into a handle and a provider identifier. Handles can themselves contain hyphens, so the provider identifier is whatever follows the last hyphen.
The client then looks the provider identifier up in an IANA registry to get a base RDAP URL. In the RFC's example, XXXX-YYYY splits into handle XXXX and provider YYYY. The registry maps YYYY to https://example.com/rdap/, and the client forms the query URL https://example.com/rdap/entity/XXXX-YYYY using the entity path segment from RFC 7482.
The client sends the full tagged handle to the provider. Only the lookup in the IANA registry uses the part after the last hyphen.
You read the school name after the last dash, look it up in a big phone book, and call that school's number to ask about the kid.
- Look up YYYYThe client splits XXXX-YYYY at the last hyphen and asks about the provider identifier.
- https://example.com/rdap/The base RDAP URL registered for YYYY.
- entity/XXXX-YYYYQuery URL: https://example.com/rdap/entity/XXXX-YYYY
§2Why the Hyphen-Minus
There is a risk if a hyphen appears in a handle for some purpose other than separating the tag. A client could wrongly treat it as a separator and look up the text after it as a provider identifier. It would likely get an unexpected, invalid result from the IANA registry. For this reason, any use of the hyphen as a provider tag separator MUST be noted with an rdapConformance value.
The RFC gives two reasons for choosing the hyphen: it is a familiar separator in operational use, and it avoids collision with URI-reserved characters. It considered the unreserved characters from RFC 3986 (letters, digits, and the characters hyphen, full stop, underscore and tilde). Letters and digits were excluded because they are commonly used in handles for non-separator purposes. The remaining characters were excluded because they are not broadly used as separators in entity handles.
A dash is the character people already use to split names, and it does not clash with the special characters that web addresses use, so it was the best pick.
§3The IANA Bootstrap Registry
IANA created a bootstrap service registry for provider object tags and makes it available as a JSON object. It uses the structure from RFC 7484. Each entry holds a contact email address, an alphanumeric provider identifier and one or more base RDAP URLs. The URLs are expected to supply the same data, though they can differ in scheme or other components.
Provider identifiers match the suffix portion (\w{1,8}) of the roidType syntax in RFC 5730. The registry is filled using the First Come First Served policy from RFC 8126. A request gives an email address, the identifier wanted (or asks IANA to assign one) and one or more base RDAP URLs. IANA also registered the extension identifier rdap_objectTag in the RDAP Extensions registry.
There is a big public phone book run by a trusted office. Each school signs up first-come, first-served and lists its name and phone number.
§4Declaring Conformance
An RDAP response that contains values described in this document MUST say so by including the rdapConformance value rdap_objectTag_level_0. This is how a client learns that a hyphen in a handle is a provider tag separator and not just part of the name.
The RFC's example response lists both rdap_level_0 and rdap_objectTag_level_0.
The answer carries a sticker saying 'my IDs end with a school tag', so nobody mistakes the dash for part of the name.
"rdapConformance" :
[
"rdap_level_0",
"rdap_objectTag_level_0"
]§6Security Considerations
The practice uses IANA as a well-known, centrally trusted authority so that users can get RDAP data from an authoritative source. That lowers the risk of sending queries to non-authoritative sources and revealing query information to unintended parties.
Protecting the connection to IANA with TLS 1.2 (RFC 5246) or TLS 1.3 (RFC 8446) lets the server authenticate itself as operated by IANA. It also gives integrity protection for the referral information and confidentiality for privacy. The later RDAP connection works as usual and keeps the security properties described in RFC 7481.
You get the phone number from a trusted phone book over a private line, so you do not call the wrong office and tell a stranger what you wanted to know.