Network Working Group K. Zeilenga Request for Comments: 3909 OpenLDAP Foundation Category: Standards Track October 2004 Lightweight Directory Access Protocol (LDAP) Cancel Operation 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) The Internet Society (2004). Abstract This specification describes a Lightweight Directory Access Protocol (LDAP) extended operation to cancel (or abandon) an outstanding operation. Unlike the LDAP Abandon operation, but like the X.511 Directory Access Protocol (DAP) Abandon operation, this operation has a response which provides an indication of its outcome. 1. Background and Intent of Use The Lightweight Directory Access Protocol (LDAP) [RFC3377] provides an Abandon operation [RFC2251] which clients may use to cancel other operations. The Abandon operation does not have a response and requires no response from the abandoned operation. These semantics provide the client with no clear indication of the outcome of the Abandon operation. The X.511 Directory Access Protocol (DAP) [X.511] provides an Abandon operation which has a response and also requires the abandoned operation to return a response indicating it was canceled. The LDAP Cancel operation is modeled after the DAP Abandon operation. The LDAP Cancel operation SHOULD be used instead of the LDAP Abandon operation when the client needs an indication of the outcome. This operation may be used to cancel both interrogation and update operations. Zeilenga Standards Track [Page 1]  RFC 3909 LDAP Cancel Operation October 2004 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]. DSA stands for Directory System Agent (or 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]. 2. Cancel Operation The Cancel operation is defined as an LDAP Extended Operation [RFC2251, Section 4.12] identified by the object identifier 1.3.6.1.1.8. This section details the syntax of the Cancel request and response messages and defines additional LDAP resultCodes. 2.1. Cancel Request The Cancel request is an ExtendedRequest with the requestName field containing 1.3.6.1.1.8 and a requestValue field which contains a BER-encoded cancelRequestValue value. cancelRequestValue ::= SEQUENCE { cancelID MessageID -- MessageID is as defined in [RFC2251] } The cancelID field contains the message ID associated with the operation to be canceled. 2.2. Cancel Response A Cancel response is an ExtendedResponse where the responseName and response fields are absent. 2.3. Additional Result Codes Implementations of this specification SHALL recognize the following additional resultCode values: canceled (118) noSuchOperation (119) tooLate (120) cannotCancel (121) Zeilenga Standards Track [Page 2]  RFC 3909 LDAP Cancel Operation October 2004 3. Operational Semantics The function of the Cancel Operation is to request that the server cancel an outstanding operation issued within the same session. The client requests the cancelation of an outstanding operation by issuing a Cancel Response with a cancelID set to the message ID of the outstanding operation. The Cancel Request itself has a distinct message ID. Clients SHOULD NOT request the cancelation of an operation multiple times. If the server is willing and able to cancel the outstanding operation identified by the cancelId, the server SHALL return a Cancel Response with a success resultCode, and the canceled operation SHALL fail with canceled resultCode. Otherwise the Cancel Response SHALL have a non-success resultCode and SHALL NOT have an impact upon the outstanding operation (if it exists). The protocolError resultCode is returned if the server is unable to parse the requestValue or the requestValue is absent, The noSuchOperation resultCode is returned if the server has no knowledge of the operation requested for cancelation. The cannotCancel resultCode is returned if the identified operation does not support cancelation or the cancel operation could not be performed. The following classes of operations are not cancelable: - operations which have no response, - operations which create, alter, or destroy authentication and/or authorization associations, - operations which establish, alter, or tear-down security services, and - operations which abandon or cancel other operations. Specifically, the Abandon, Bind, Start TLS [RFC2830], Unbind, and Cancel operations are not cancelable. The Cancel operation cannot be abandoned. The tooLate resultCode is returned to indicate that it is too late to cancel the outstanding operation. For example, the server may return tooLate for a request to cancel an outstanding modify operation which has already committed updates to the underlying data store. Zeilenga Standards Track [Page 3]  RFC 3909 LDAP Cancel Operation October 2004 Servers SHOULD indicate their support for this extended operation by providing 1.3.6.1.1.8 as a value of the 'supportedExtension' attribute type in their root DSE. A server MAY choose to advertise this extension only when the client is authorized to use it. 4. Security Considerations This operation is intended to allow a user to cancel operations they previously issued during the current LDAP association. In certain cases, such as when the Proxy Authorization Control is in use, different outstanding operations may be processed under different LDAP associations. Servers MUST NOT allow a user to cancel an operation belonging to another user. Some operations should not be cancelable for security reasons. This specification disallows the cancelation of the Bind operation and Start TLS extended operation so as to avoid adding complexity to authentication, authorization, and security layer semantics. Designers of future extended operations and/or controls should disallow abandonment and cancelation when appropriate. 5. IANA Considerations The following values [RFC3383] have been registered by the IANA. 5.1. Object Identifier The IANA has registered upon Standards Action the LDAP Object Identifier 1.3.6.1.1.8 to identify the LDAP Cancel Operation as 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 3909 Author/Change Controller: IESG Comments: Identifies the LDAP Cancel Operation Zeilenga Standards Track [Page 4]  RFC 3909 LDAP Cancel Operation October 2004 5.2. LDAP Protocol Mechanism The IANA has registered upon Standards Action the LDAP Protocol Mechanism described in this document. Subject: LDAP Protocol Mechanism Registration Object Identifier: 1.3.6.1.1.8 Description: LDAP Cancel Operation Person & email address to contact for further information: Kurt Zeilenga <kurt@openldap.org> Usage: Extended Operation Specification: RFC 3909 Author/Change Controller: IESG Comments: none 5.3. LDAP Result Codes The IANA has registered upon Standards Action the LDAP Result Codes described in this document. Subject: LDAP Result Code Registration Person & email address to contact for further information: Kurt Zeilenga <kurt@OpenLDAP.org> Result Code Name: canceled (118) Result Code Name: noSuchOperation (119) Result Code Name: tooLate (120) Result Code Name: cannotCancel (121) Specification: RFC 3909 Author/Change Controller: IESG 6. Acknowledgment The LDAP Cancel operation is modeled after the X.511 DAP Abandon operation. Zeilenga Standards Track [Page 5]  RFC 3909 LDAP Cancel Operation October 2004 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2251] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. [RFC2830] Hodges, J., Morgan, R., and M. Wahl, "Lightweight Directory Access Protocol (v3): Extension for Transport Layer Security", RFC 2830, May 2000. [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). 7.2. Informative References [RFC3383] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", BCP 64, RFC 3383, September 2002. [X.511] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory: Abstract Service Definition", X.511(1993). 8. Author's Address Kurt D. Zeilenga OpenLDAP Foundation EMail: Kurt@OpenLDAP.org Zeilenga Standards Track [Page 6]  RFC 3909 LDAP Cancel Operation October 2004 9. Full Copyright Statement Copyright (C) The Internet Society (2004). 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Zeilenga Standards Track [Page 7]