mirror of
https://git.friendi.ca/friendica/friendica-addons.git
synced 2024-11-09 19:02:59 +00:00
451 lines
14 KiB
Text
451 lines
14 KiB
Text
|
||
|
||
|
||
|
||
|
||
|
||
Internet Engineering Task Force (IETF) M. Nottingham
|
||
Request for Comments: 5785 E. Hammer-Lahav
|
||
Updates: 2616, 2818 April 2010
|
||
Category: Standards Track
|
||
ISSN: 2070-1721
|
||
|
||
|
||
Defining Well-Known Uniform Resource Identifiers (URIs)
|
||
|
||
Abstract
|
||
|
||
This memo defines a path prefix for "well-known locations",
|
||
"/.well-known/", in selected Uniform Resource Identifier (URI)
|
||
schemes.
|
||
|
||
Status of This Memo
|
||
|
||
This is an Internet Standards Track document.
|
||
|
||
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
|
||
Internet Standards is available in Section 2 of RFC 5741.
|
||
|
||
Information about the current status of this document, any errata,
|
||
and how to provide feedback on it may be obtained at
|
||
http://www.rfc-editor.org/info/rfc5785.
|
||
|
||
Copyright Notice
|
||
|
||
Copyright (c) 2010 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.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 1]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
Table of Contents
|
||
|
||
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
|
||
1.1. Appropriate Use of Well-Known URIs . . . . . . . . . . . . 3
|
||
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
|
||
3. Well-Known URIs . . . . . . . . . . . . . . . . . . . . . . . . 3
|
||
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
|
||
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
|
||
5.1. The Well-Known URI Registry . . . . . . . . . . . . . . . . 4
|
||
5.1.1. Registration Template . . . . . . . . . . . . . . . . . 5
|
||
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
|
||
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
|
||
6.2. Informative References . . . . . . . . . . . . . . . . . . 5
|
||
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 7
|
||
Appendix B. Frequently Asked Questions . . . . . . . . . . . . . . 7
|
||
|
||
1. Introduction
|
||
|
||
It is increasingly common for Web-based protocols to require the
|
||
discovery of policy or other information about a host ("site-wide
|
||
metadata") before making a request. For example, the Robots
|
||
Exclusion Protocol <http://www.robotstxt.org/> specifies a way for
|
||
automated processes to obtain permission to access resources;
|
||
likewise, the Platform for Privacy Preferences [W3C.REC-P3P-20020416]
|
||
tells user-agents how to discover privacy policy beforehand.
|
||
|
||
While there are several ways to access per-resource metadata (e.g.,
|
||
HTTP headers, WebDAV's PROPFIND [RFC4918]), the perceived overhead
|
||
(either in terms of client-perceived latency and/or deployment
|
||
difficulties) associated with them often precludes their use in these
|
||
scenarios.
|
||
|
||
When this happens, it is common to designate a "well-known location"
|
||
for such data, so that it can be easily located. However, this
|
||
approach has the drawback of risking collisions, both with other such
|
||
designated "well-known locations" and with pre-existing resources.
|
||
|
||
To address this, this memo defines a path prefix in HTTP(S) URIs for
|
||
these "well-known locations", "/.well-known/". Future specifications
|
||
that need to define a resource for such site-wide metadata can
|
||
register their use to avoid collisions and minimise impingement upon
|
||
sites' URI space.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 2]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
1.1. Appropriate Use of Well-Known URIs
|
||
|
||
There are a number of possible ways that applications could use Well-
|
||
known URIs. However, in keeping with the Architecture of the World-
|
||
Wide Web [W3C.REC-webarch-20041215], well-known URIs are not intended
|
||
for general information retrieval or establishment of large URI
|
||
namespaces on the Web. Rather, they are designed to facilitate
|
||
discovery of information on a site when it isn't practical to use
|
||
other mechanisms; for example, when discovering policy that needs to
|
||
be evaluated before a resource is accessed, or when using multiple
|
||
round-trips is judged detrimental to performance.
|
||
|
||
As such, the well-known URI space was created with the expectation
|
||
that it will be used to make site-wide policy information and other
|
||
metadata available directly (if sufficiently concise), or provide
|
||
references to other URIs that provide such metadata.
|
||
|
||
2. Notational Conventions
|
||
|
||
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].
|
||
|
||
3. Well-Known URIs
|
||
|
||
A well-known URI is a URI [RFC3986] whose path component begins with
|
||
the characters "/.well-known/", and whose scheme is "HTTP", "HTTPS",
|
||
or another scheme that has explicitly been specified to use well-
|
||
known URIs.
|
||
|
||
Applications that wish to mint new well-known URIs MUST register
|
||
them, following the procedures in Section 5.1.
|
||
|
||
For example, if an application registers the name 'example', the
|
||
corresponding well-known URI on 'http://www.example.com/' would be
|
||
'http://www.example.com/.well-known/example'.
|
||
|
||
Registered names MUST conform to the segment-nz production in
|
||
[RFC3986].
|
||
|
||
Note that this specification defines neither how to determine the
|
||
authority to use for a particular context, nor the scope of the
|
||
metadata discovered by dereferencing the well-known URI; both should
|
||
be defined by the application itself.
|
||
|
||
Typically, a registration will reference a specification that defines
|
||
the format and associated media type to be obtained by dereferencing
|
||
the well-known URI.
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 3]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
It MAY also contain additional information, such as the syntax of
|
||
additional path components, query strings and/or fragment identifiers
|
||
to be appended to the well-known URI, or protocol-specific details
|
||
(e.g., HTTP [RFC2616] method handling).
|
||
|
||
Note that this specification does not define a format or media-type
|
||
for the resource located at "/.well-known/" and clients should not
|
||
expect a resource to exist at that location.
|
||
|
||
4. Security Considerations
|
||
|
||
This memo does not specify the scope of applicability of metadata or
|
||
policy obtained from a well-known URI, and does not specify how to
|
||
discover a well-known URI for a particular application. Individual
|
||
applications using this mechanism must define both aspects.
|
||
|
||
Applications minting new well-known URIs, as well as administrators
|
||
deploying them, will need to consider several security-related
|
||
issues, including (but not limited to) exposure of sensitive data,
|
||
denial-of-service attacks (in addition to normal load issues), server
|
||
and client authentication, vulnerability to DNS rebinding attacks,
|
||
and attacks where limited access to a server grants the ability to
|
||
affect how well-known URIs are served.
|
||
|
||
5. IANA Considerations
|
||
|
||
5.1. The Well-Known URI Registry
|
||
|
||
This document establishes the well-known URI registry.
|
||
|
||
Well-known URIs are registered on the advice of one or more
|
||
Designated Experts (appointed by the IESG or their delegate), with a
|
||
Specification Required (using terminology from [RFC5226]). However,
|
||
to allow for the allocation of values prior to publication, the
|
||
Designated Expert(s) may approve registration once they are satisfied
|
||
that such a specification will be published.
|
||
|
||
Registration requests should be sent to the
|
||
wellknown-uri-review@ietf.org mailing list for review and comment,
|
||
with an appropriate subject (e.g., "Request for well-known URI:
|
||
example").
|
||
|
||
Before a period of 14 days has passed, the Designated Expert(s) will
|
||
either approve or deny the registration request, communicating this
|
||
decision both to the review list and to IANA. Denials should include
|
||
an explanation and, if applicable, suggestions as to how to make the
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 4]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
request successful. Registration requests that are undetermined for
|
||
a period longer than 21 days can be brought to the IESG's attention
|
||
(using the iesg@iesg.org mailing list) for resolution.
|
||
|
||
5.1.1. Registration Template
|
||
|
||
URI suffix: The name requested for the well-known URI, relative to
|
||
"/.well-known/"; e.g., "example".
|
||
|
||
Change controller: For Standards-Track RFCs, state "IETF". For
|
||
others, give the name of the responsible party. Other details
|
||
(e.g., postal address, e-mail address, home page URI) may also be
|
||
included.
|
||
|
||
Specification document(s): Reference to the document that specifies
|
||
the field, preferably including a URI that can be used to retrieve
|
||
a copy of the document. An indication of the relevant sections
|
||
may also be included, but is not required.
|
||
|
||
Related information: Optionally, citations to additional documents
|
||
containing further relevant information.
|
||
|
||
6. References
|
||
|
||
6.1. Normative References
|
||
|
||
[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.
|
||
|
||
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
|
||
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
|
||
May 2008.
|
||
|
||
6.2. Informative References
|
||
|
||
[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.
|
||
|
||
[RFC4918] Dusseault, L., "HTTP Extensions for Web Distributed
|
||
Authoring and Versioning (WebDAV)", RFC 4918, June 2007.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 5]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
[W3C.REC-P3P-20020416]
|
||
Marchiori, M., "The Platform for Privacy Preferences 1.0
|
||
(P3P1.0) Specification", World Wide Web Consortium
|
||
Recommendation REC-P3P-20020416, April 2002,
|
||
<http://www.w3.org/TR/2002/ REC-P3P-20020416>.
|
||
|
||
[W3C.REC-webarch-20041215]
|
||
Jacobs, I. and N. Walsh, "Architecture of the World Wide
|
||
Web, Volume One", World Wide Web Consortium
|
||
Recommendation REC- webarch-20041215, December 2004,
|
||
<http:// www.w3.org/TR/2004/REC-webarch-20041215>.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 6]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
Appendix A. Acknowledgements
|
||
|
||
We would like to acknowledge the contributions of everyone who
|
||
provided feedback and use cases for this document; in particular,
|
||
Phil Archer, Dirk Balfanz, Adam Barth, Tim Bray, Brian Eaton, Brad
|
||
Fitzpatrick, Joe Gregorio, Paul Hoffman, Barry Leiba, Ashok Malhotra,
|
||
Breno de Medeiros, John Panzer, and Drummond Reed. However, they are
|
||
not responsible for errors and omissions.
|
||
|
||
Appendix B. Frequently Asked Questions
|
||
|
||
1. Aren't well-known locations bad for the Web?
|
||
|
||
They are, but for various reasons -- both technical and social --
|
||
they are commonly used and their use is increasing. This memo
|
||
defines a "sandbox" for them, to reduce the risks of collision and
|
||
to minimise the impact upon pre-existing URIs on sites.
|
||
|
||
2. Why /.well-known?
|
||
|
||
It's short, descriptive, and according to search indices, not
|
||
widely used.
|
||
|
||
3. What impact does this have on existing mechanisms, such as P3P and
|
||
robots.txt?
|
||
|
||
None, until they choose to use this mechanism.
|
||
|
||
4. Why aren't per-directory well-known locations defined?
|
||
|
||
Allowing every URI path segment to have a well-known location
|
||
(e.g., "/images/.well-known/") would increase the risks of
|
||
colliding with a pre-existing URI on a site, and generally these
|
||
solutions are found not to scale well, because they're too
|
||
"chatty".
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 7]
|
||
|
||
RFC 5785 Defining Well-Known URIs April 2010
|
||
|
||
|
||
Authors' Addresses
|
||
|
||
Mark Nottingham
|
||
|
||
EMail: mnot@mnot.net
|
||
URI: http://www.mnot.net/
|
||
|
||
|
||
Eran Hammer-Lahav
|
||
|
||
EMail: eran@hueniverse.com
|
||
URI: http://hueniverse.com/
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Hammer-Lahav Standards Track [Page 8]
|
||
|