One document matched: draft-ietf-weirds-using-http-04.txt
Differences from draft-ietf-weirds-using-http-03.txt
Network Working Group A.L. Newton
Internet-Draft ARIN
Intended status: Standards Track B.J. Ellacott
Expires: October 17, 2013 APNIC
N. Kong
CNNIC
April 17, 2013
HTTP usage in the Registration Data Access Protocol (RDAP)
draft-ietf-weirds-using-http-04
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).
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 October 17, 2013.
Copyright Notice
Copyright (c) 2013 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 (http://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
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This document describes the usage of HTTP 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 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 GET. 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 known query/response model used by HTTP
[RFC2616]. 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, multiple response formats are supported by this protocol. At
present the IETF WEIRDS working group is defining only a JSON
[RFC4627] response format, but server operators may use other data
formats when those formats are requested.
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.
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.
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4. Queries
4.1. Accept Header
RDAP clients MUST include an Accept: header field specifying
application/rdap+json, application/json, or both. Servers receiving
an RDAP request MUST return an entity with Content-Type application/
rdap+json.
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 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. 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 encodes the answer in the format most appropriate according to the
standard and defined rules for processing the HTTP Accept header
field, and return 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 MUST return a 301 response code to
indicate a permanent move, or a 307 response code to indicate a non-
permanent redirection, and include an HTTP(s) URL in the Location:
header field. The client is expected to issue a 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/
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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 no information regarding
the query, it MUST return 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 MUST return 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 SHOULD return 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
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).
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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 / "_" )
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).
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.
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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>
Intended usage: COMMON
8.2. RDAP Media Type Registration
This specification registers the "application/rdap+json" media type.
Type name: application
Subtype name: rdap+json
Required parameters: n/a
Encoding considerations: n/a
Security considerations: n/a
Interoperability considerations: n/a
Published specification: [[ this document ]]
Applications that use this media type: RDAP
Additional information: n/a
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Person & email address to contact for further information: Andy
Newton <andy@hxr.us>
Intended usage: COMMON
Restrictions on usage: none
Author: Andy Newton
Change controller: IETF
Provisional Registration: Yes
9. Internationalization Considerations
9.1. URIs and IRIs
Clients MAY use IRIs [RFC3987] 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 clients MAY transform
these URIs to IRIs.
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
[RFC2616] 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.
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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.
Jean-Phillipe Dionne provided text for the Security Considerations
section.
11. References
[SAC-051] Piscitello, D., Ed., "SSAC Report on Domain Name WHOIS
Terminology and Structure", September 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC3912] Daigle, L., "WHOIS Protocol Specification", RFC 3912,
September 2004.
[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.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[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.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, April 2012.
[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>.
Appendix A. Protocol Example
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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 301 Moved Permanently
Location: http://rdap-ip.example.com/ip/203.0.113.0/24
Content-Length: 0
Content-Type: application/rdap+json; charset=UTF-8
<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 200 OK
Content-Type: application/rdap_json; charset=UTF-8
Content-Length: 9001
{ ... }
<TCP disconnect>
Appendix B. Cache Busting
Some HTTP [RFC2616] 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 MAY use an
adhoc and improbably used query parameter with a random value of
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
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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
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
-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.
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* Added and corrected references: CORS, RFC3912, RFC3987,
RFC5890.
* Expanded on first use several acronyms.
* Updated 2119 language.
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
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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