





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                                26 October 2003


                         LDAP Read Entry Controls
                  <draft-zeilenga-ldap-readentry-01.txt>


1.      Status of this Memo

  This document is an Internet-Draft and is in full conformance with all
  provisions of Section 10 of RFC2026.

  This document is intended to be, after appropriate review and
  revision, submitted to the RFC Editor as a Standard Track document.
  Distribution of this memo is unlimited.  Technical discussion of this
  document will take place on the IETF LDAP Extensions mailing list
  <ldapext@ietf.org>.  Please send editorial comments directly to the
  author <Kurt@OpenLDAP.org>.

  Internet-Drafts are working documents of the Internet Engineering Task
  Force (IETF), its areas, and its working groups.  Note that other
  groups may also distribute working documents as Internet-Drafts.
  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.''

  The list of current Internet-Drafts can be accessed at
  <http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
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  <http://www.ietf.org/shadow.html>.

  Copyright (C) The Internet Society (2003).  All Rights Reserved.

  Please see the Full Copyright section near the end of this document
  for more information.


Abstract

  This specification describes controls which can be attached to a
  Lightweight Directory Access Protocol (LDAP) update request to obtain
  copies of the target entry before and/or after the requested update is
  applied.





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1. Background and Intent of Use

  This specification describes controls [RFC2251] which can be attached
  to Lightweight Directory Access Protocol (LDAP) [RFC3377] update
  requests to request and return copies of the target entry.  One
  request control, called the Pre-Read request control, indicates that a
  copy of the entry before application of update is to be returned.
  Another control, called the Post-Read request control, indicates that
  a copy of the entry after application of the update is to be returned.
  Each request control has a corresponding response control used to
  return the entry.

  The functionality offered by these controls is based upon similar
  functionality in the X.500 Directory Access Protocol (DAP) [X.511].

  The Pre-Read controls may be used to obtain replaced or deleted values
  of modified attributes or a copy of the entry being deleted.

  The Post-Read controls may be used to obtain values of operational
  attributes, such as the 'entryUUID' [EntryUUID] and 'modifytimestamp'
  [RFC2252] attributes, updated by the server as part of the update
  operation.


2. Terminology

  Protocol elements are described using ASN.1 [X.680] with implicit
  tags.  The term "BER-encoded" means the element is to be encoded using
  the Basic Encoding Rules [X.690] under the restrictions detailed in
  Section 5.1 of [RFC2251].

  DN stands for Distinguished Name.
  DSA stands for Directory System Agent (i.e., a directory server).
  DSE stands for DSA-specific Entry.

  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 BCP 14 [RFC2119].


3. Read Entry Controls

3.1. The Pre-Read Controls

  The Pre-Read request and response controls are identified by the
  IANA-ASSIGNED-OID.1 object identifier.  Servers implementing these
  controls SHOULD publish IANA-ASSIGNED-OID.1 as a value of the
  'supportedControl' [RFC2252] in their root DSE.



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  The Pre-Read request control is an LDAP Control [RFC2251] whose
  controlType is IANA-ASSIGNED-OID.1 and controlValue is a BER-encoded
  AttributeDescriptionList [RFC2251].  The criticality may be TRUE or
  FALSE.  This control is appropriate for the modifyRequest, delRequest,
  and modDNRequest LDAP messages.

  The corresponding response control is a LDAP Control whose controlType
  is IANA-ASSIGNED-OID.1 and the controlValue, an OCTET STRING, contains
  a BER-encoded SearchResultEntry.  The criticality may be TRUE or
  FALSE.  This control is appropriate for the modifyResponse,
  delResponse, and modDNResponse LDAP messages with a resultCode of
  success (0).

  When the request control is attached to an appropriate update LDAP
  request, the control requests the return of a copy of target entry
  prior to the application of the update.  The AttributeDescriptionList
  indicates which attributes are requested to appear in the copy.  There
  are two special AttributeDescriptions which may be included in the
  list, "*" and "+".  "*" requests all user attributes.  "+" requests
  all operational attributes.  If the list is empty, all user attributes
  are requested.  If the list contains an unrecognized attribute type,
  that type is simply ignored.  If all attribute types are unrecognized,
  no attributes are to be returned.  The server is to return a
  SearchResultEntry containing, subject to access controls and other
  constraints, values of the requested attributes.

  The normal processing of the update operation and the processing of
  this control MUST be performed as one atomic action isolated from
  other update operations.

  If the update operation fails, no response control is provided.


3.2. The Post-Read Controls

  The Post-Read request and response controls are identified by the
  IANA-ASSIGNED-OID.2 object identifier.  Servers implementing these
  controls SHOULD publish IANA-ASSIGNED-OID.2 as a value of the
  'supportedControl' [RFC2252] in their root DSE.

  The Post-Read request control is an LDAP Control [RFC2251] whose
  controlType is IANA-ASSIGNED-OID.2 and controlValue, an OCTET STRING,
  contains a BER-encoded AttributeDescriptionList [RFC2251].  The
  criticality may be TRUE or FALSE.  This control is appropriate for the
  addRequest, modifyRequest, and modDNRequest LDAP messages.

  The corresponding response control is a LDAP Control whose controlType
  is IANA-ASSIGNED-OID.2 and controlValue is a BER-encoded



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  SearchResultEntry.  The criticality may be TRUE or FALSE.  This
  control is appropriate for the addResponse, modifyResponse, and
  modDNResponse LDAP messages with a resultCode of success (0).

  When the request control is attached to an appropriate update LDAP
  request, the control requests the return of a copy of target entry
  after the application of the update.  The AttributeDescriptionList
  indicates which attributes are requested to appear in the copy.  There
  are two special AttributeDescriptions which may be included in the
  list, "*" and "+".  "*" requests all user attributes.  "+" requests
  all operational attributes.  If the list is empty, all user attributes
  are requested.  If the list contains an unrecognized attribute type,
  that type is simply ignored.  If all attribute types are unrecognized,
  no attributes are to be returned.  The server is to return a
  SearchResultEntry containing, subject to access controls and other
  constraints, values of the requested attributes.

  The normal processing of the update operation and the processing of
  this control MUST be performed as one atomic action isolated from
  other update operations.

  If the update operation fails, no response control is provided.


4. Interaction with other controls

  The Pre- and Post-Read controls may be combined with each other and/or
  with a variety of other controls.  When combined with the assertion
  control [ASSERT], the manageDsaIT control [RFC3296], and/or the proxy
  authorization control [PROXYAUTH], the semantics of each control
  included in the combination apply.  The Pre- and Post-Read controls
  may be combined with other controls as detailed in other technical
  specifications.


5. Security Considerations

  The controls defined in this document extend update operations to
  support read capabilities.  Servers MUST ensure that the client is
  authorized both for reading of the information provided in this
  control in addition to ensuring the client is authorized to perform
  the requested directory update.

  Implementors of this (or any) LDAP extension should be familiar with
  general LDAP security considerations [RFC3377].


6.  IANA Considerations



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  Registration of the following protocol values [RFC3383] is requested.


6.1.  Object Identifier

  It is requested that IANA register an LDAP Object Identifier to
  identify LDAP protocol elements defined in this document.

      Subject: Request for LDAP Object Identifier Registration
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
      Specification: RFC XXXX
      Author/Change Controller: IESG
      Comments:
           Identifies the LDAP Read Entry Controls


6.2.  LDAP Protocol Mechanisms

  It is requested that IANA register the LDAP Protocol Mechanism
  described in this document.

      Subject: Request for LDAP Protocol Mechanism Registration
      Object Identifier: IANA-ASSIGNED-OID.1
      Description: LDAP Pre-read Control
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@openldap.org>
      Usage: Control
      Specification: RFC XXXX
      Author/Change Controller: IESG
      Comments: none
      in 2

      Subject: Request for LDAP Protocol Mechanism Registration
      Object Identifier: IANA-ASSIGNED-OID.2
      Description: LDAP Post-read Control
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@openldap.org>
      Usage: Control
      Specification: RFC XXXX
      Author/Change Controller: IESG
      Comments: none
      in 2


7. Acknowledgment

      The LDAP Pre- and Post-Read controls are modeled after similar



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      capabilities offered in the DAP [X.511].


8. Normative References

  [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14 (also RFC 2119), March 1997.

  [RFC2251]     Wahl, M., T. Howes and S. Kille, "Lightweight Directory
                Access Protocol (v3)", RFC 2251, December 1997.

  [RFC2252]     Wahl, M., A. Coulbeck, T. Howes, and S. Kille,
                "Lightweight Directory Access Protocol (v3):  Attribute
                Syntax Definitions", RFC 2252, December 1997.

  [RFC2830]     Hodges, J., R. Morgan, and M. Wahl, "Lightweight
                Directory Access Protocol (v3): Extension for Transport
                Layer Security", RFC 2830, May 2000.

  [RFC3296]     Zeilenga, K., "Named Subordinate References in
                Lightweight Directory Access Protocol (LDAP)
                Directories", RFC 3296, July 2002.

  [RFC3377]     Hodges, J. and R. Morgan, "Lightweight Directory Access
                Protocol (v3): Technical Specification", RFC 3377,
                September 2002.

  [X.680]       International Telecommunication Union -
                Telecommunication Standardization Sector, "Abstract
                Syntax Notation One (ASN.1) - Specification of Basic
                Notation", X.680(1997) (also ISO/IEC 8824-1:1998).

  [X.690]       International Telecommunication Union -
                Telecommunication Standardization Sector, "Specification
                of ASN.1 encoding rules: Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER), and Distinguished
                Encoding Rules (DER)", X.690(1997) (also ISO/IEC
                8825-1:1998).

  [PROXYAUTH]   Weltman, R., "LDAP Proxy Authentication Control", draft-
                weltman-ldapv3-proxy-xx.txt, a work in progress.

  [ASSERT]      Zeilenga, K., "LDAP Assertion Control",
                draft-zeilenga-ldap-assert-xx.txt, a work in progress.


9. Informative References




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  [RFC3383]     Zeilenga, K., "IANA Considerations for LDAP", BCP 64
                (also RFC 3383), September 2002.

  [X.511]       International Telecommunication Union -
                Telecommunication Standardization Sector, "The
                Directory: Abstract Service Definition", X.511(1993).

  [EntryUUID]   Zeilenga, K., "The LDAP EntryUUID Operational
                Attribute", draft-zeilenga-ldap-uuid-xx.txt, a work in
                progress.


10. Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation
  <Kurt@OpenLDAP.org>



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Full Copyright

  Copyright (C) The Internet Society (2003). All Rights Reserved.




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