Network Working Group W. Sanchez
Internet-Draft C. Daboo
Expires: November 14, 2008 Apple Inc.
May 13, 2008
WebDAV Current Principal Extension
draft-sanchez-webdav-current-principal-00
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Abstract
This specification defines a new WebDAV property that allows clients
to quickly determine the principal corresponding to the current
authenticated user.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . . 3
3. DAV:current-user-principal-resource . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
WebDAV [RFC4918] is an extension to HTTP [RFC2616] to support
improved document authoring capabilities. The WebDAV ACL [RFC3744]
extension adds access control capabilities to WebDAV. It introduces
the concept of a "principal resource" which is used to represent
information about authenticated entities on the system.
Some clients have a need to determine the [RFC3744] principal that a
server is associating with the currently authenticated HTTP user.
While [RFC3744] defines a DAV:current-user-privilege-set property for
retrieving the privileges granted to that principal, there is no
recommended way to do identify the principal in question, which is
necessary to perform other useful operations. For example, a client
may wish to determine which groups the current user is a member of,
or modify a property of the principal resource associated with the
current user.
The DAV:principal-match REPORT provides some useful functionality,
but there are common situations where the results from that query can
be ambiguous (e.g. not only is an individual user principal returned,
but also every group principal that the user is a member of, and
there is no clear way to distinguish which is which).
This specification proposes an extension to WebDAV ACL that adds a
DAV:current-user-principal-resource property to all resources under
access control on the server. This property contains a single DAV:
href element whose value is a URL to the principal resource
corresponding to the currently authenticated user.
2. Conventions Used in This Document
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 [RFC2119].
When XML element types in the namespace "DAV:" are referenced in this
document outside of the context of an XML fragment, the string "DAV:"
will be prefixed to the element type names.
3. DAV:current-user-principal-resource
Name: current-user-principal-resource
Namespace: DAV:
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Purpose: Indicates a URL for the current authenticated user's
principal resource on the server.
Value: Single DAV:href element.
Protected: This property is computed on a per-request basis, and
therefore is protected.
Description: The DAV:current-user-principal-resource property
contains either a DAV:href or DAV:unauthenticed XML element. The
DAV:href element contains a URL to a principal resource
corresponding to the currently authenticated user. That URL MUST
be one of the URLs in the DAV:principal-URL or DAV:alternate-URI-
set properties defined on the principal resource and MUST be an
http(s) scheme URL. When authentication has not been done or has
failed, this property MUST contain the DAV:unauthenticated pseudo-
principal.
In some cases there may be multiple principal resources
corresponding to the same authenticated principal. In that case
the server is free to choose any one of the principal resource
URIs for the value of the DAV:current-user-principal-resource
property. However, servers SHOULD be consistent and use the same
principal resource URI for each authenticated principal.
COPY/MOVE behavior: This property is computed on a per-request
basis, and is thus never copied or moved.
Definition:
<!ELEMENT current-user-principal-resource (DAV:unauthenticated |
DAV:href)>
DAV:href value: a URL to a principal resource
Example:
<D:current-user-principal-resource xmlns:D="DAV:">
<D:href>/principals/users/cdaboo</D:href>
</D:current-user-principal-resource>
4. Security Considerations
This specification does not introduce any additional security issues
beyond those defined in HTTP [RFC2616], WebDAV [RFC4918] and WebDAV
ACL [RFC3744].
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5. IANA Considerations
This document does not require any actions on the part of IANA.
6. Acknowledgments
This specification was suggested by discussion that took place within
the Calendaring and Scheduling Consortium's CalDAV Technical
Committee. The authors thank the participants of that group for
their input.
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web
Distributed Authoring and Versioning (WebDAV)
Access Control Protocol", RFC 3744, May 2004.
[RFC4918] Dusseault, L., "HTTP Extensions for Web Distributed
Authoring and Versioning (WebDAV)", RFC 4918, June 2007.
Authors' Addresses
Wilfredo Sanchez
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
EMail: wsanchez@wsanchez.net
URI: http://www.apple.com/
Cyrus Daboo
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
EMail: cyrus@daboo.name
URI: http://www.apple.com/
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