WebDAV Current Principal Extension
RFC 5397

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Network Working Group                                         W. Sanchez
Request for Comments: 5397                                      C. Daboo
Category: Standards Track                                     Apple Inc.
                                                           December 2008

                   WebDAV Current Principal Extension

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2008 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.

Abstract

   This specification defines a new WebDAV property that allows clients
   to quickly determine the principal corresponding to the current
   authenticated user.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Conventions Used in This Document . . . . . . . . . . . . . . . 2
   3.  DAV:current-user-principal  . . . . . . . . . . . . . . . . . . 3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . . . 4

Sanchez & Daboo              Standards Track                    [Page 1]
RFC 5397                WebDAV Current Principal           December 2008

1.  Introduction

   WebDAV [RFC4918] is an extension to HTTP [RFC2616] to support
   improved document authoring capabilities.  The WebDAV Access Control
   Protocol ("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 which [RFC3744] principal 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 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.  For example, 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 property to resources under access control
   on the server.  This property provides a URL to a principal resource
   corresponding to the currently authenticated user.  This allows a
   client to "bootstrap" itself by performing additional queries on the
   principal resource to obtain additional information from that
   resource, which is the purpose of this extension.  Note that while it
   is possible for multiple URLs to refer to the same principal
   resource, or for multiple principal resources to correspond to a
   single principal, this specification only allows for a single http(s)
   URL in the DAV:current-user-principal property.  If a client wishes
   to obtain alternate URLs for the principal, it can query the
   principal resource for this information; it is not the purpose of
   this extension to provide a complete list of such URLs, but simply to
   provide a means to locate a resource which contains that (and other)
   information.

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].

Sanchez & Daboo              Standards Track                    [Page 2]
RFC 5397                WebDAV Current Principal           December 2008

   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.

   Processing of XML by clients and servers MUST follow the rules