Network Working Group K. Zeilenga

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.

Table of Contents

1. Background and Intended Use .....................................1
2. The Modify-Increment Extension ..................................2
3. LDIF Support ....................................................2
4. Security Considerations .........................................3
5. IANA Considerations .............................................3
5.1. Object Identifier ..........................................3
5.2. LDAP Protocol Mechanism ....................................3
5.3. LDAP Protocol Mechanism ....................................4
6. References ......................................................4
6.1. Normative References .......................................4
6.2. Informative References .....................................5

1. 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

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RFC 4525 LDAP Modify-Increment Extension June 2006

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].

2. 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.

3. 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

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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.

4. 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.

5. IANA Considerations

Registration of the following values [RFC4520] have been completed.

5.1. 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

5.2. 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]>

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RFC 4525 LDAP Modify-Increment Extension June 2006

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

5.3. 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

6. References

6.1. 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.

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RFC 4525 LDAP Modify-Increment Extension June 2006

6.2. 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]

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RFC 4525 LDAP Modify-Increment Extension June 2006

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Copyright (C) The Internet Society (2006).

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