RFC4525

Network Working Group K. Zeilenga Request for Comments: 4525 OpenLDAP Foundation Category: Informational June 2006

          Lightweight Directory Access Protocol (LDAP)
                   Modify-Increment Extension

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

This document describes an extension to the Lightweight Directory Access Protocol (LDAP) Modify operation to support an increment capability. This extension is useful in provisioning applications, especially when combined with the assertion control and/or the pre- read or post-read control extension.

Background and Intended Use

The Lightweight Directory Access Protocol (LDAP) RFC4510 does not currently provide an operation to increment values of an attribute. A client must read the values of the attribute and then modify those values to increment them by the desired amount. As the values may be updated by other clients between this add and modify, the client must

be careful to construct the modify request so that it fails in this case, and upon failure, to re-read the values and construct a new modify request.

This document extends the LDAP Modify Operation RFC4511 to support an increment values capability. This feature is intended to be used with either the LDAP pre-read or post-read control extensions RFC4527. This feature may also be used with the LDAP assertion control extension RFC4528 to provide test-and-increment functionality.

In this document 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.

The Modify-Increment Extension

This document extends the LDAP Modify request to support a increment values capability. Implementations of this extension SHALL support an additional ModifyRequest operation enumeration value increment (3), as described herein. Implementations not supporting this extension will treat this value as they would an unlisted value, e.g., as a protocol error.

The increment (3) operation value specifies that an increment values modification is requested. All existing values of the modification attribute are to be incremented by the listed value. The modification attribute must be appropriate for the request (e.g., it must have INTEGER or other increment-able values), and the modification must provide one and only one value. If the attribute is not appropriate for the request, a constraintViolation or other appropriate error is to be returned. If multiple values are provided, a protocolError is to be returned.

Servers supporting this feature SHOULD publish the object identifier (OID) 1.3.6.1.1.14 as a value of the 'supportedFeatures' RFC4512 attribute in the root DSE. Clients supporting this feature SHOULD NOT use the feature unless they know the server supports it.

LDIF Support

To represent Modify-Increment requests in LDAP Data Interchange Format RFC2849, the ABNF RFC4234 production <mod-spec> is extended as follows:

   mod-spec =/ "increment:" FILL AttributeDescription SEP
        attrval-spec "-" SEP

For example,

   # Increment uidNumber
   dn: cn=max-assigned uidNumber,dc=example,dc=com
   changetype: modify
   increment: uidNumber
   uidNumber: 1
   -

This LDIF fragment represents a Modify request to increment the value(s) of uidNumber by 1.

Security Considerations

General LDAP security considerations RFC4510, as well as those specific to the LDAP Modify RFC4511, apply to this Modify-Increment extension. Beyond these considerations, it is noted that introduction of this extension should reduce application complexity (by providing one operation for what presently requires multiple operations) and, hence, it may aid in the production of correct and secure implementations.

IANA Considerations

Registration of the following values RFC4520 have been completed.

Object Identifier

The IANA has assigned an LDAP Object Identifier to identify the LDAP Modify-Increment feature, as defined in this document.

   Subject: Request for LDAP Object Identifier Registration
   Person & email address to contact for further information:
       Kurt Zeilenga <[email protected]>
   Specification: RFC 4525
   Author/Change Controller: Author
   Comments:
       Identifies the LDAP Modify-Increment feature

LDAP Protocol Mechanism

The following LDAP Protocol Mechanism has been registered.

   Subject: Request for LDAP Protocol Mechanism Registration
   Object Identifier: 1.3.6.1.1.14
   Description: Modify-Increment
   Person & email address to contact for further information:
       Kurt Zeilenga <[email protected]>

   Usage: Feature
   Specification: RFC 4525
   Author/Change Controller: Kurt Zeilenga <[email protected]>
   Comments: none

LDAP Protocol Mechanism

The IANA has assigned an LDAP ModifyRequest Operation Type (3) RFC4520 for use in this document.

   Subject: Request for LDAP Protocol Mechanism Registration
   ModifyRequest Operation Name: increment
   Description: Modify-Increment
   Person & email address to contact for further information:
       Kurt Zeilenga <[email protected]>
   Usage: Feature
   Specification: RFC 4525
   Author/Change Controller: Kurt Zeilenga <[email protected]>
   Comments: none

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. and P. Overell, "Augmented BNF for Syntax

             Specifications: ABNF", RFC 4234, October 2005.

RFC2849 Good, G., "The LDAP Data Interchange Format (LDIF) -

             Technical Specification", RFC 2849, June 2000.

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.

Informative References

RFC4520 Zeilenga, K., "Internet Assigned Numbers Authority

             (IANA) Considerations for the Lightweight Directory
             Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.

RFC4527 Zeilenga, K., "Lightweight Directory Access Protocol

             (LDAP) Read Entry Controls", RFC 4527, June 2006.

RFC4528 Zeilenga, K., "Lightweight Directory Access Protocol

             (LDAP) Assertion Control", RFC 4528, June 2006.

Author's Address

Kurt D. Zeilenga OpenLDAP Foundation

EMail: [email protected]

Full Copyright Statement

Copyright (C) The Internet Society (2006).

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