Network Working Group A. Newton
Internet-Draft ARIN
Intended status: Standards Track B. Ellacott
Expires: February 8, 2015 APNIC
N. Kong
CNNIC
August 7, 2014
HTTP usage in the Registration Data Access Protocol (RDAP)
draft-ietf-weirds-using-http-09
Abstract
This document is one of a collection that together describe the
Registration Data Access Protocol (RDAP). It describes how RDAP is
transported using the Hypertext Transfer Protocol (HTTP).
Normative Reference Note
Normative references to RFC 7231 and draft-ietf-httpbis-http2 can be
replaced with a reference to RFC 2616 if draft-ietf-httpbis-http2 is
still a work in progress when this document is ready for publication.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 8, 2015.
Copyright Notice
Copyright (c) 2014 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
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(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Design Intents . . . . . . . . . . . . . . . . . . . . . . . 4
4. Queries . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Accept Header . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Query Parameters . . . . . . . . . . . . . . . . . . . . 5
5. Types of HTTP Response . . . . . . . . . . . . . . . . . . . 5
5.1. Positive Answers . . . . . . . . . . . . . . . . . . . . 5
5.2. Redirects . . . . . . . . . . . . . . . . . . . . . . . . 5
5.3. Negative Answers . . . . . . . . . . . . . . . . . . . . 6
5.4. Malformed Queries . . . . . . . . . . . . . . . . . . . . 6
5.5. Rate Limits . . . . . . . . . . . . . . . . . . . . . . . 6
5.6. Cross-Origin Resource Sharing . . . . . . . . . . . . . . 7
6. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8.1. RDAP Extensions Registry . . . . . . . . . . . . . . . . 8
9. Internationalization Considerations . . . . . . . . . . . . . 9
9.1. URIs and IRIs . . . . . . . . . . . . . . . . . . . . . . 9
9.2. Language Identifiers in Queries and Responses . . . . . . 9
9.3. Language Identifiers in HTTP Headers . . . . . . . . . . 9
10. Contributing Authors and Acknowledgements . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
11.1. Normative References . . . . . . . . . . . . . . . . . . 10
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Appendix A. Protocol Example . . . . . . . . . . . . . . . . . . 11
Appendix B. Cache Busting . . . . . . . . . . . . . . . . . . . 11
Appendix C. Changelog . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
This document describes the usage of HTT[RFC7231]P for Registration
Data Directory Services. The goal of this document is to tie
together usage patterns of HTTP into a common profile applicable to
the various types of Directory Services serving Registration Data
using RESTful practices. By giving the various Directory Services
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common behavior, a single client is better able to retrieve data from
Directory Services adhering to this behavior.
The registration data expected to be presented by this service is
Internet resource registration data - registration of domain names
and Internet number resources. This data is typically provided by
WHOIS [RFC3912] services, but the WHOIS protocol is insufficient to
modern registration data service requirements. A replacement
protocol is expected to retain the simple transactional nature of
WHOIS, while providing a specification for queries and responses,
redirection to authoritative sources, support for Internationalized
Domain Names (IDNs, [RFC5890]), and support for localized
registration data such as addresses and organisation or person names.
In designing these common usage patterns, this document introduces
considerations for a simple use of HTTP. Where complexity may
reside, it is the goal of this document to place it upon the server
and to keep the client as simple as possible. A client
implementation should be possible using common operating system
scripting tools.
This is the basic usage pattern for this protocol:
1. A client issues an HTTP query using GE[I-D.ietf-httpbis-http2]T.
As an example, a query for the network registration 192.0.2.0
might be http://example.com/ip/192.0.2.0.
2. If the receiving server has the information for the query, it
examines the Accept header field of the query and returns a 200
response with a response entity appropriate for the requested
format.
3. If the receiving server does not have the information for the
query but does have knowledge of where the information can be
found, it will return a redirection response (3xx) with the
Location: header field containing an HTTP(S) URL (Uniform
Resource Locator) pointing to the information or another server
known to have knowledge of the location of the information. The
client is expected to re-query using that HTTP URL.
4. If the receiving server does not have the information being
requested and does not have knowledge of where the information
can be found, it returns a 404 response.
5. If the receiving server will not answer a request for policy
reasons, it will return an error response (4xx) indicating the
reason for giving no answer.
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It is important to note that it is not the intent of this document to
redefine the meaning and semantics of HTTP. The purpose of this
document is to clarify the use of standard HTTP mechanisms for this
application.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
As is noted in SSAC Report on WHOIS Terminology and Structure
[SAC-051], the term "WHOIS" is overloaded, often referring to a
protocol, a service and data. In accordance with [SAC-051], this
document describes the base behavior for a Registration Data Access
Protocol (RDAP). [SAC-051] describes a protocol profile of RDAP for
Domain Name Registries (DNRs), the Domain Name Registration Data
Access Protocol (DNRD-AP).
In this document, an RDAP client is an HTTP User Agent performing an
RDAP query, and an RDAP server is an HTTP server providing an RDAP
response. RDAP query and response formats are described in other
documents in the collection of RDAP specifications, while this
document describes how RDAP clients and servers use HTTP to exchange
queries and responses.
3. Design Intents
There are a few design criteria this document attempts to meet.
First, each query is meant to return either zero or one result. With
the maximum upper bound being set to one, the issuance of redirects
is simplified to the traditional query/response model used by HTTP
[RFC7231]. Should an entity contain more than one result, some of
which are better served by other servers, the redirection model
becomes much more complicated.
Second, the semantics of the request/response allow for future and/or
non-standard response formats. In this document, only a JSON
[RFC4627] response media type is noted, with the response contents to
be described separately. This document only describes how RDAP is
transported using HTTP with this format.
Third, this protocol is intended to be able to make use of the range
of mechanisms available for use with HTTP. HTTP offers a number of
mechanisms not described further in this document. Operators are
able to make use of these mechanisms according to their local policy,
including cache control, authorization, compression, and redirection.
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HTTP also benefits from widespread investment in scalability,
reliability, and performance, and widespread programmer understanding
of client behaviours for RESTful web services, reducing the cost to
deploy Registration Data Directory Services and clients.
4. Queries
4.1. Accept Header
To indicate to servers that an RDAP response is desired, clients
include an Accept: header field with an RDAP specific JSON media
type, the generic JSON media type, or both. Servers receiving an
RDAP request return an entity with a Content-Type: header containing
the RDAP specific JSON media type.
This specification does not define the responses a server returns to
a request with any other media types in the Accept: header field, or
with no Accept: header field. One possibility would be to return a
response in a media type suitable for rendering in a web browser.
4.2. Query Parameters
Servers MUST ignore unknown query parameters. Use of unknown query
parameters for cache-busting is described in Appendix B.
5. Types of HTTP Response
This section describes the various types of responses a server may
send to a client. While no standard HTTP response code is forbidden
in usage, at a minimum clients SHOULD understand the response codes
described in this section as they will be in common use by servers.
It is expected that usage of response codes and types for this
application not defined here will be described in subsequent
documents.
5.1. Positive Answers
If a server has the information requested by the client and wishes to
respond to the client with the information according to its policies,
it returns that answer in the body of a 200 response.
5.2. Redirects
If a server wishes to inform a client that the answer to a given
query can be found elsewhere, it returns either a 301 response code
to indicate a permanent move, or a 302, 303 or 307 response code to
indicate a non-permanent redirection, and it includes an HTTP(s) URL
in the Location: header field. The client is expected to issue a
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subsequent request to satisfy the original query using the given URL
without any processing of the URL. In other words, the server is to
hand back a complete URL and the client should not have to transform
the URL to follow it.
For this application, such an example of a permanent move might be a
Top Level Domain (TLD) operator informing a client the information
being sought can be found with another TLD operator (i.e. a query for
the domain bar in foo.example is found at http://foo.example/domain/
bar).
For example, if the client sends
http://serv1.example.com/weirds/domain/example.com, the server
redirecting to https://serv2.example.net/weirds2/ would set the
Location: field to the value:
https://serv2.example.net/weirds2/domain/example.com.
5.3. Negative Answers
If a server wishes to respond that it has an empty result set, it
returns a 404 response code. Optionally, it MAY include additional
information regarding the negative answer in the HTTP entity body.
If a server wishes to inform the client that information about the
query is available, but cannot include the information in the
response to the client for policy reasons, the server MUST respond
with an appropriate response code out of HTTP's 4xx range. Clients
MAY retry the query based on the respective response code.
5.4. Malformed Queries
If a server receives a query which it cannot interpret as an RDAP
query, it returns a 400 response code. Optionally, it MAY include
additional information regarding this negative answer in the HTTP
entity body.
5.5. Rate Limits
Some servers apply rate limits to deter address scraping and other
abuses. When a server declines to answer a query due to rate limits,
it returns a 429 response code as described in [RFC6585]. A client
that receives a 429 response SHOULD decrease its query rate, and
honor the Retry-After header field if one is present.
Note that this is not a defense against denial-of-service attacks,
since a malicious client could ignore the code and continue to send
queries at a high rate. A server might use another response code if
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it did not wish to reveal to a client that rate limiting is the
reason for the denial of a reply.
5.6. Cross-Origin Resource Sharing
When responding to queries, it is RECOMMENDED that servers use the
Access-Control-Allow-Origin header field, as specified by
[W3C.CR-cors-20130129].
6. Extensibility
For extensibility purposes, this document defines an IANA registry
for prefixes used in JSON [RFC4627] data serialization and URI path
segments (see Section 8).
Prefixes and identifiers SHOULD only consist of the alphabetic ASCII
characters A through Z in both uppercase and lowercase, the numerical
digits 0 through 9, underscore characters, and SHOULD NOT begin with
an underscore character, numerical digit or the characters "xml".
The following describes the production of JSON names in ABNF
[RFC5234].
ABNF for JSON names
name = ALPHA *( ALPHA / DIGIT / "_" )
Figure 1
This restriction is a union of the Ruby programming language
identifier syntax and the XML element name syntax and has two
purposes. First, client implementers using modern programming
languages such as Ruby or Java can use libraries that automatically
promote JSON names to first order object attributes or members.
Second, a clean mapping between JSON and XML is easy to accomplish
using these rules.
7. Security Considerations
This document does not pose strong security requirements to the RDAP
protocol. However, it does not restrict against the use of security
mechanisms offered by the HTTP protocol.
This document made recommendations for server implementations against
denial-of-service (Section 5.5) and interoperability with existing
security mechanism in HTTP clients (Section 5.6).
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Additional security considerations to the RDAP protocol will be
covered in future RFCs documenting specific security mechanisms and
schemes.
8. IANA Considerations
8.1. RDAP Extensions Registry
This specification proposes an IANA registry for RDAP extensions.
The purpose of this registry is to ensure uniqueness of extension
identifiers. The extension identifier is used as a prefix in JSON
names and as a prefix of path segments in RDAP URLs.
The production rule for these identifiers is specified in Section 6.
In accordance with RFC5226, the IANA policy for assigning new values
shall be Specification Required: values and their meanings must be
documented in an RFC or in some other permanent and readily available
reference, in sufficient detail that interoperability between
independent implementations is possible.
The following is a preliminary template for an RDAP extension
registration:
Extension identifier: the identifier of the extension
Registry operator: the name of the registry operator
Published specification: RFC number, bibliographical reference or
URL to a permanent and readily available specification
Person & email address to contact for further information: The
names and email addresses of individuals for contact regarding
this registry entry
Intended usage: brief reasons for this registry entry
The following is an example of a registration in the RDAP extension
registry:
Extension identifier: lunarNic
Registry operator: The Registry of the Moon, LLC
Published specification: http://www.example/moon_apis/rdap
Person & email address to contact for further information:
Professor Bernardo de la Paz <berny@moon.example>
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Intended usage: COMMON
9. Internationalization Considerations
9.1. URIs and IRIs
Clients can use IRIs [RFC3987] for internal use as they see fit, but
MUST transform them to URIs [RFC3986] for interaction with RDAP
servers. RDAP servers MUST use URIs in all responses, and again
clients can transform these URIs to IRIs for internal use as they see
fit.
9.2. Language Identifiers in Queries and Responses
Under most scenarios, clients requesting data will not signal that
the data be returned in a particular language or script. On the
other hand, when servers return data and have knowledge that the data
is in a language or script, the data SHOULD be annotated with
language identifiers whenever they are available, thus allowing
clients to process and display the data accordingly.
The mechanism for including a language identifier in a response will
be defined in subsequent documents describing specific response
formats.
9.3. Language Identifiers in HTTP Headers
Given the description of the use of language identifiers in
Section 9.2, unless otherwise specified servers SHOULD ignore the
HTTP [RFC7231] Accept-Language header field when formulating HTTP
entity responses, so that clients do not conflate the Accept-Language
header with the 'lang' values in the entity body.
However, servers MAY return language identifiers in the Content-
Language header field so as to inform clients of the intended
language of HTTP layer messages.
10. Contributing Authors and Acknowledgements
John Levine provided text to tighten up the Accept header field usage
and the text for the section on 429 responses.
Marc Blanchet provided some clarifying text regarding the use of URLs
with redirects, as well as very useful feedback during WGLC.
Normative language reviews were provided by Murray S. Kucherawy and
Andrew Sullivan.
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Jean-Phillipe Dionne provided text for the Security Considerations
section.
11. References
11.1. Normative References
[I-D.ietf-httpbis-http2]
Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
Protocol version 2", draft-ietf-httpbis-http2-14 (work in
progress), July 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, April 2012.
[RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Semantics and Content", RFC 7231, June 2014.
[W3C.CR-cors-20130129]
Kesteren, A., "Cross-Origin Resource Sharing", World Wide
Web Consortium Candidate Recommendation CR-cors-20130129,
January 2013,
<http://www.w3.org/TR/2013/CR-cors-20130129>.
11.2. Informative References
[RFC3912] Daigle, L., "WHOIS Protocol Specification", RFC 3912,
September 2004.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework",
RFC 5890, August 2010.
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[SAC-051] Piscitello, D., Ed., "SSAC Report on Domain Name WHOIS
Terminology and Structure", September 2011.
Appendix A. Protocol Example
To demonstrate typical behaviour of an RDAP client and server, the
following is an example of an exchange, including a redirect. The
data in the response has been elided for brevity, as the data format
is not described in this document.
An example of an RDAP client and server exchange:
Client:
<TCP connect to rdap.example.com port 80>
GET /ip/203.0.113.0/24 HTTP/1.1
Host: rdap.example.com
Accept: application/rdap+json
rdap.example.com:
HTTP/1.1 301 Moved Permanently
Location: http://rdap-ip.example.com/ip/203.0.113.0/24
Content-Length: 0
Content-Type: application/rdap+json
<TCP disconnect>
Client:
<TCP connect to rdap-ip.example.com port 80>
GET /ip/203.0.113.0/24 HTTP/1.1
Host: rdap-ip.example.com
Accept: application/rdap+json
rdap-ip.example.com:
HTTP/1.1 200 OK
Content-Type: application/rdap+json
Content-Length: 9001
{ ... }
<TCP disconnect>
Appendix B. Cache Busting
Some HTTP [RFC7231] cache infrastructure does not adhere to caching
standards adequately, and could cache responses longer than is
intended by the server. To overcome these issues, clients can use an
adhoc and improbably used query parameter with a random value of
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their choosing. As Section 4.2 instructs servers to ignore unknown
parameters, this is unlikely to have any known side effects.
An example of using an unknown query parameter to bust caches:
http://example.com/ip/192.0.2.0?__fuhgetaboutit=xyz123
Use of an unknown parameter to overcome misbehaving caches is not
part of any specification and is offered here for informational
purposes.
Appendix C. Changelog
RFC Editor: Please remove this section.
Initial WG -00: Updated to working group document 2012-September-20
-01
* Updated for the sections moved to the JSON responses draft.
* Simplified media type, removed "level" parameter.
* Updated 2119 language and added boilerplate.
* In section 1, noted that redirects can go to redirect servers
as well.
* Added Section 9.2 and Section 9.3.
-02
* Added a section on 429 response codes.
* Changed Accept header language in section 4.1
* Removed reference to the now dead requirements draft.
* Added contributing authors and acknowledgements section.
* Added some clarifying text regarding complete URLs in the
redirect section.
* Changed media type to application/rdap+json
* Added media type registration
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-03
* Removed forward reference to draft-ietf-weirds-json-response.
* Added reference and recommended usage of CORS
-04
* Revised introduction and abstract.
* Added negative responses other than 404.
* Added security considerations.
* Added and corrected references: CORS, RFC3912, RFC3987,
RFC5890.
* Expanded on first use several acronyms.
* Updated 2119 language.
-05
* Update the media type registration.
* Further explained the SHOULD in section 5.
* Split the references into normative and informative.
* Other minor fixes.
-06
* Rewritten the third paragraph in Section 3 to avoid
contradictions
* Simplified the wording in Seciton 5.1.
* Removed some RFC 2119 words in Section 5.2, 5.3, 5.4 and 5.5.
* Corrected RFC 6839 as an informative reference.
* Replaced MAYs with cans in Seciton 9.1.
* Replaced MAY with can in Appendix B.
* Added a note in in Appendix C for the RFC Editor to remove this
section.
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-07
* Dropped reference to MUST with application/rdap+json
* Dropped IANA registration of application/rdap+json
-08
* Keep alive version.
-09
* Changed status lines in example to include http version number.
* Removed charset from media types in examples.
* Changed wording of 404 negative response to specifically say
"empty result set".
* Changed references to HTTP.
Authors' Addresses
Andrew Lee Newton
American Registry for Internet Numbers
3635 Concorde Parkway
Chantilly, VA 20151
US
Email: andy@arin.net
URI: http://www.arin.net
Byron J. Ellacott
Asia Pacific Network Information Center
6 Cordelia Street
South Brisbane QLD 4101
Australia
Email: bje@apnic.net
URI: http://www.apnic.net
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Ning Kong
China Internet Network Information Center
4 South 4th Street, Zhongguancun, Haidian District
Beijing 100190
China
Phone: +86 10 5881 3147
Email: nkong@cnnic.cn
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