Network Working Group N. Freed Internet-Draft Sun Microsystems Expires: September 20, 2007 March 19, 2007 Sieve Email Filtering: Environment Extension draft-freed-sieve-environment-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 20, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes the "environment" extension to the Sieve email filtering language. The "environment" extension gives Sieve access to information about the environment where the Sieve interpreter is running. Change History (to be removed prior to publication as an RFC Changed one place string result from "UA" to "MUA". Freed Expires September 20, 2007 [Page 1] Internet-Draft Sieve Environment Extension March 2007 Updated the IANA registration template Moved the ihave extension to a separate document. 1. Introduction Sieve [I-D.ietf-sieve-3028bis] is a language for filtering email messages at or around the time of final delivery. It is designed to be implementable on either a mail client or mail server. It is suitable for running on a mail server where users may not be allowed to execute arbitrary programs, such as on black box Internet Message Access Protocol [RFC3501] servers, as it has no user-controlled loops or the ability to run external programs. Although sieve is intended to be independent of access protocol, mail architecture, and operating system, in some cases it is useful to allow scripts to access information about their execution context. The "environment" extension provides a new environment test that can be used to implement scripts that behave differently when moved from one system to another or otherwise operated in different contexts. 2. Conventions used in this document 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]. The terms used to describe the various components of the Sieve language are taken from [I-D.ietf-sieve-3028bis] section 1.1. 3. Capability Identifiers The capability string associated with the extension defined in this document is "environment". 4. Environment Test Usage: environment [COMPARATOR] [MATCH-TYPE] The environment test retrieves the item of environment information specified by the name string and matches it to the values specified in the key-list. The test succeeds if a match occurs. The type of Freed Expires September 20, 2007 [Page 2] Internet-Draft Sieve Environment Extension March 2007 match defaults to ":is" and the default comparator is "i;ascii- casemap". The current message is not a direct source of information for the environment test; the item of information specified by the name string is extracted from the environment and key-list comes from the script. The environment test MUST fail unconditionally if the specified information item does not exist. A script MUST NOT fail with an error if the item does not exist. This allows scripts to be written that handle nonexistent items gracefully. The "relational" extension [I-D.ietf-sieve-3431bis] adds a match type called ":count". The count of an environment test is 0 if the environment information returned is the empty string, or 1 otherwise. Environment items can be standardized or vendor-defined. An IANA registry is defined for both types of items. 4.1. Standard Environment Items The initial set of standardized environment items is as follows: "name" => the product name associated with the Sieve interpreter "version" => the product version associated with the Sieve interpreter "host" => the fully-qualified domain name of the host where the Sieve script is executing "domain" => the primary DNS domain associated with the Sieve execution context, usually but not always a proper suffix of the host name "evaluation-time" => Sieve processing is normally performing around or after the time of final delivery. This item provides additional information about the relationship to final delivery. Possible return values are "MTA", meaning the Sieve is being evaluated before final delivery, "MDA", meaning evaluation is occurring during final delivery", and "MUA", meaning evaluation is occurring after final delivery. Implementations SHOULD support as many of the items on this initial list as possible. Additional standardized items can only be defined in standards-track or experimental RFCs. Freed Expires September 20, 2007 [Page 3] Internet-Draft Sieve Environment Extension March 2007 4.2. Vendor-defined Environment Items Environment item names beginning with "vnd." represent vendor-defined extensions. Such extensions are not defined by Internet standards or RFCs, but are still registered with IANA in order to prevent conflicts. Environment item names starting with "vnd." SHOULD be followed by the name of the vendor and product, such as "vnd.acme.rocket-sled-status". 4.3. IANA Registration of Environment Items A registry of environment items is provided by IANA. Item names may be registered on a first-come, first-served basis. Extensions designed for interoperable use SHOULD be defined as standards track or IESG approved experimental RFCs. 4.3.1. Template for Environment Registrations The following template is to be used for registering new Sieve environment item names with IANA. To: iana@iana.org Subject: Registration of new Sieve environment item Item name: [the string for use in the 'environment' test] Description: [a brief description of the semantics of the value the item returns] RFC number: [for extensions published as RFCs] Contact address: [email and/or physical address to contact for additional information] 4.3.2. Initial Environment Item Registrations TBD once the initial list has been determined. 5. Security Considerations The environment extension may be used to obtain information about the system the sieve implementation is running on. This information in turn may reveal details about service provider or enterprise infrastructure. All of the security considerations given in the base Sieve specification also apply to this extension. Freed Expires September 20, 2007 [Page 4] Internet-Draft Sieve Environment Extension March 2007 6. IANA Considerations This specification defines a new IANA registry for Sieve environment item names. The specifics of this registry are given in Section 4.3. The following templates specify the IANA registrations of the two Sieve extensions specified in this document: To: iana@iana.org Subject: Registration of new Sieve extension Capability name: environment Description: The "environment" extension provides a new environment test that can be used to implement scripts that behave differently when moved from one system to another or otherwise operated in different contexts. RFC number: RFC XXXX Contact address: Ned Freed This information should be added to the list of sieve extensions given on http://www.iana.org/assignments/sieve-extensions. 7. References 7.1. Normative references [I-D.ietf-sieve-3028bis] Guenther, P. and T. Showalter, "Sieve: An Email Filtering Language", draft-ietf-sieve-3028bis-12 (work in progress), February 2007, . [I-D.ietf-sieve-3431bis] Segmuller, W. and B. Leiba, "Sieve Extension: Relational Tests", draft-ietf-sieve-3431bis-04 (work in progress), December 2005, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative references [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1", RFC 3501, March 2003. Freed Expires September 20, 2007 [Page 5] Internet-Draft Sieve Environment Extension March 2007 Author's Address Ned Freed Sun Microsystems 3401 Centrelake Drive, Suite 410 Ontario, CA 92761-1205 USA Phone: +1 909 457 4293 Email: ned.freed@mrochek.com Freed Expires September 20, 2007 [Page 6] Internet-Draft Sieve Environment Extension March 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. 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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Freed Expires September 20, 2007 [Page 7]