RFC4529
Network Working Group K. Zeilenga Request for Comments: 4529 OpenLDAP Foundation Category: Informational June 2006
Requesting Attributes by Object Class in the
Lightweight Directory Access Protocol (LDAP)
Status of This Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
The Lightweight Directory Access Protocol (LDAP) search operation provides mechanisms for clients to request all user application attributes, all operational attributes, and/or attributes selected by their description. This document extends LDAP to support a mechanism that LDAP clients may use to request the return of all attributes of an object class.
Contents
Background and Intended Use
In the Lightweight Directory Access Protocol (LDAP) RFC4510, the search operation RFC4511 supports requesting the return of a set of attributes. This set is determined by a list of attribute descriptions. Two special descriptors are defined to request all user attributes ("*") RFC4511 and all operational attributes ("+") RFC3673. However, there is no convenient mechanism for requesting pre-defined sets of attributes such as the set of attributes used to represent a particular class of object.
This document extends LDAP to allow an object class identifier to be specified in attributes lists, such as in Search requests, to request the return of all attributes belonging to an object class. The COMMERCIAL AT ("@", U+0040) character is used to distinguish an object class identifier from an attribute descriptions.
For example, the attribute list of "@country" is equivalent to the attribute list of 'c', 'searchGuide', 'description', and 'objectClass'. This object class is described in RFC4519.
This extension is intended primarily to be used where the user is in direct control of the parameters of the LDAP search operation, for instance when entering an LDAP URL RFC4516 into a web browser, such as <ldap:///dc=example,dc=com?@organization?base>.
Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14 RFC2119.
DSA stands for Directory System Agent (or server). DSE stands for DSA-specific Entry.
Return of All Attributes of an Object Class
This extension allows object class identifiers to be provided in the attributes field of the LDAP SearchRequest RFC4511 or other request values of the AttributeSelection data type (e.g., attributes field in pre/post read controls [ReadEntry]) and/or <attributeSelector> production (e.g., attributes of an LDAP URL RFC4516). For each object class identified in the attributes field, the request is to be treated as if each attribute allowed by that class (by "MUST" or "MAY", directly or by "SUP"erior) RFC4512 were itself listed.
This extension extends the <attributeSelector> RFC4511 production as indicated by the following ABNF RFC4234:
attributeSelector =/ objectclassdescription
objectclassdescription = ATSIGN oid options
ATSIGN = %x40 ; COMMERCIAL AT ("@" U+0040)
where <oid> and <options> productions are as defined in RFC4512.
The <oid> component of an <objectclassdescription> production identifies the object class by short name (descr) or object identifier (numericoid). If the value of the <oid> component is unrecognized or does not refer to an object class, the object class description is to be treated as an unrecognized attribute description.
The <options> production is included in the grammar for extensibility purposes. An object class description with an unrecognized or inappropriate option is to be treated as unrecognized.
Although object class description options and attribute description options share the same syntax, they are not semantically related. This document does not define any object description option.
Servers supporting this feature SHOULD publish the object identifier (OID) 1.3.6.1.4.1.4203.1.5.2 as a value of the 'supportedFeatures' RFC4512 attribute in the root DSE. Clients supporting this feature SHOULD NOT use the feature unless they know that the server supports it.
Security Considerations
This extension provides a shorthand for requesting all attributes of an object class. Because these attributes could have been listed individually, introduction of this shorthand is not believed to raise additional security considerations.
Implementors of this LDAP extension should be familiar with security considerations applicable to the LDAP search operation RFC4511, as well as with general LDAP security considerations RFC4510.
IANA Considerations
Registration of the LDAP Protocol Mechanism RFC4520 defined in this document has been completed.
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: 1.3.6.1.4.1.4203.1.5.2
Description: OC AD Lists
Person & email address to contact for further information:
Kurt Zeilenga <[email protected]>
Usage: Feature
Specification: RFC 4529
Author/Change Controller: Kurt Zeilenga <[email protected]>
Comments: none
This OID was assigned [ASSIGN] by OpenLDAP Foundation, under its IANA-assigned private enterprise allocation [PRIVATE], for use in this specification.
References
Normative References
RFC2119 Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
RFC4234 Crocker, D., Ed. and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", RFC 4234, October 2005.
RFC4510 Zeilenga, K., Ed., "Lightweight Directory Access
Protocol (LDAP): Technical Specification Road Map", RFC
4510, June 2006.
RFC4511 Sermersheim, J., Ed., "Lightweight Directory Access
Protocol (LDAP): The Protocol", RFC 4511, June 2006.
RFC4512 Zeilenga, K., "Lightweight Directory Access Protocol
(LDAP): Directory Information Models", RFC 4512, June 2006.
RFC4516 Smith, M., Ed. and T. Howes, "Lightweight Directory
Access Protocol (LDAP): Uniform Resource Locator", RFC
4516, June 2006.
[X.680] International Telecommunication Union -
Telecommunication Standardization Sector, "Abstract
Syntax Notation One (ASN.1) - Specification of Basic
Notation", X.680(2002) (also ISO/IEC 8824-1:2002).
Informative References
RFC3673 Zeilenga, K., "Lightweight Directory Access Protocol
version 3 (LDAPv3): All Operational Attributes", RFC
3673, December 2003.
RFC4519 Sciberras, A., Ed., "Lightweight Directory Access
Protocol (LDAP): Schema for User Applications", RFC
4519, June 2006.
RFC4520 Zeilenga, K., "Internet Assigned Numbers Authority
(IANA) Considerations for the Lightweight Directory
Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.
[ReadEntry] Zeilenga, K., "Lightweight Directory Access Protocol
(LDAP) Read Entry Controls", RFC 4527, June 2006.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
Author's Address
Kurt D. Zeilenga OpenLDAP Foundation
EMail: [email protected]
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