Network Working Group C. Daboo Internet Draft: SIEVE Include Extension Document: draft-daboo-sieve-include-01.txt October 2003 SIEVE Include Extension Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Copyright Notice Copyright (C) The Internet Society 2003. All Rights Reserved. Daboo Expires April 2004 [Page 1] Internet Draft SIEVE Include Extension October 2003 Abstract The SIEVE [SIEVE] "include" extension permits users to include one SIEVE script inside another. This can make managing large scripts or multiple sets of scripts much easier, as well as supporting common 'libraries' of scripts. Users are able to include their own personal scripts or site-wide scripts provided by the local SIEVE implementation. Change History (to be removed prior to publication as an RFC) Changes from -00 to -01: 1 Added IPR boiler plate. 2 Re-ordered sections at start to conform to RFC style. 3 Moved recursion comment into General Considerations section. 4 Switched to using optional parameter to indicate personal vs global. 5 Explicitly state that an error occurs when a missing script is included. Table of Contents 1 Introduction and Overview . . . . . . . . . . . . . . . . . . 2 2 Conventions Used in This Document . . . . . . . . . . . . . . 2 3 SIEVE Include Extension . . . . . . . . . . . . . . . . . . . 3 3.1 General Considerations . . . . . . . . . . . . . . . . . . 3 3.2 Control Structure Include . . . . . . . . . . . . . . . . 3 3.3 Control Structure Return . . . . . . . . . . . . . . . . . 6 4 Security Considerations . . . . . . . . . . . . . . . . . . . 7 5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5.1 include registration . . . . . . . . . . . . . . . . . . 7 6 Normative References . . . . . . . . . . . . . . . . . . . . . 7 7 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 8 9 Intellectual Property Rights Statement . . . . . . . . . . . 8 10 Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8 1 Introduction and Overview Its convenient to be able to break SIEVE scripts down into smaller components which can be reused in a variety of different circumstances. For example, users may want to have a default script and a special 'vacation' script, the later being activated when the user goes on vacation. In that case the default actions should continue to be run, but a vacation command should be executed first. One option is to edit the default script to add or remove the vacation command as needed. Another is to have a vacation script that simply has a vacation command and then includes the default script. Daboo Expires April 2004 [Page 2] Internet Draft SIEVE Include Extension October 2003 2 Conventions Used in This Document Conventions for notations are as in [SIEVE] section 1.1, including use of [KEYWORDS]. 3 SIEVE Include Extension 3.1 General Considerations SIEVE implementations that implement the "include" and "return" control structures described below have an identifier of "include" for use with the capability mechanism. If either of the "include" or "return" control structures are used in a script, the "include" capability MUST be listed in the "require" statement in that script. SIEVE implementations must track the use of actions in included scripts so that implicit "keep" behaviour can be properly determined based on whether any actions have executed in any script. SIEVE implementations are allowed to limit the total number of nested included scripts, but MUST provide for a total of at least three levels of nested scripts including the top-level script. An error MUST be generated either when the script is uploaded to the SIEVE repository, or when the script is executed, if any nesting limit is exceeded. If such an error is detected whilst processing a SIEVE script, an implicit "keep" action MUST be executed to prevent loss of any messages. SIEVE implementations MUST ensure that recursive includes are not possible. i.e. if script "A" includes script "B", and script "B" includes script "A" an error MUST be generated either when the script is uploaded to the SIEVE repository, or when the script is executed. If such an error is detected whilst processing a SIEVE script, an implicit "keep" action MUST be executed to prevent loss of any messages. SIEVE implementations MUST handle missing scripts being referenced via an includes in an existing script. An error MUST be generated when a missing included script is descovered during execution. If such an error is detected an implicit "keep" action MUST be executed to prevent loss of any messages. 3.2 Control Structure Include Syntax: include [LOCATION] The "include" control structure includes an optional parameter, and a single string argument representing the name of the script to include in the main script at that point. Daboo Expires April 2004 [Page 3] Internet Draft SIEVE Include Extension October 2003 [LOCATION] is an optional parameter that has one of two values: Syntax: ":personal" / ":global" If the [LOCATION] parameter is not present, the location defaults to :personal. The location has the following meanings: :personal Indicates that the named script is stored in the user's own personal (private) SIEVE repository. :global Indicates that the named script is stored in a site-wide SIEVE repository, accessible to all users of the SIEVE system. The included script MUST be a valid SIEVE script, including having necessary "require" statements for all optional capabilities used by the script. The scope of a "require" statement in an included script is for that script only, not the including script. e.g. if script "A" includes script "B", and script "B" uses the "fileinto" extension, script "B" must have a "require" statement for "fileinto", irrespective of whether script "A" has one. In addition, if script "A" does not have a "require" statement for "fileinto", "fileinto" cannot be used anywhere in script "A", even after inclusion of script "B". A "stop" control statement in an included script MUST stop all script processing, including the processing of the scripts that include the current one. The "return" control statement (described below) stops processing of the current script only, and allows the scripts that include it to continue. Examples: In the examples below, script content is indicated by a '|' as the first non-space character on a line for clarity. The '|' characters are not part of the script itself. The user has four scripts stored in their personal repository: Daboo Expires April 2004 [Page 4] Internet Draft SIEVE Include Extension October 2003 "default" This is the default active script that includes several others. | require ["include"]; | | include :personal "always_allow"; | include :global "spam_tests"; | include :personal "my_spam_tests"; | include :personal "mailing_lists"; "always_allow" This script special cases some correspondent email addresses and makes sure any message containing those addresses are always kept. | if header :is "From" "boss@example.com" | { | keep; | } | elsif header :is "From" "ceo@example.com" | { | keep; | } "my_spam_tests" This script does some user-specific spam tests to catch spam messages not caught by the site-wide spam tests. | require ["reject"]; | | if header :contains "Subject" "XXXX" | { | reject; | } | elsif header :is "From" "money@example.com" | { | reject; | } Daboo Expires April 2004 [Page 5] Internet Draft SIEVE Include Extension October 2003 "mailing_lists" This script looks for messages from different mailing lists and files each into a mailbox specific to the mailing list. | require ["fileinto"]; | | if header :is "Sender" "owner-ietf-mta-filters@imc.org" | { | fileinto "lists.sieve"; | } | elsif header :is "Sender" "owner-ietf-imapext@imc.org" | { | fileinto "lists.imapext"; | } There is one script stored in the global repository: "spam_tests" This script does some site-wide spam tests which any user at the site can include in their own scripts at a suitable point. The script content is kept up to date by the site administrator. | require ["reject"]; | | if anyof (header :contains "Subject" "$$", | header :contains "Subject" "Make money") | { | reject; | } The "include" control structure may appear anywhere in the script where a control structure is legal. Example: | require ["include"]; | | if anyof (header :contains "Subject" "$$", | header :contains "Subject" "Make money") | { | include "my_reject_script"; | } 3.3 Control Structure Return Syntax: return The "return" control structure stops processing of the currently included script only and returns processing control to the script which includes it. If used in the main script (i.e. not in an Daboo Expires April 2004 [Page 6] Internet Draft SIEVE Include Extension October 2003 included script), it has the same effect as the "stop" control structure, including the appropriate "keep" action if no other actions have been executed up to that point. 4 Security Considerations SIEVE implementations MUST ensure adequate security for the global script repository to prevent unauthorized changes to global scripts. Beyond that, the "include" extension does not raise any security considerations that are not present in the base [SIEVE] protocol, and these issues are discussed in [SIEVE]. 5 IANA Considerations The following template specifies the IANA registration of the Sieve extension specified in this document: 5.1 include registration To: iana@iana.org Subject: Registration of new Sieve extension Capability name: include Capability keyword: include Capability arguments: N/A Standards Track/IESG-approved experimental RFC number: this RFC Person and email address to contact for further information: Cyrus Daboo Cyrusoft International, Inc. 5001 Baum Blvd., Suite 780, Pittsburgh, PA 15213 U.S.A. This information should be added to the list of sieve extensions given on http://www.iana.org/assignments/sieve-extensions. 6 Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [SIEVE] Showalter, "Sieve: A Mail Filtering Language", RFC 3028, January 2001. Daboo Expires April 2004 [Page 7] Internet Draft SIEVE Include Extension October 2003 7 Acknowledgments Thanks to Ken Murchison, Rob Siemborski, Alexey Melnikov, Marc Mutz and Kjetil Torgrim Homme for comments and corrections. 8 Author's Address Cyrus Daboo Cyrusoft International, Inc. 5001 Baum Blvd., Suite 780, Pittsburgh, PA 15213 U.S.A. 9 Intellectual Property Rights Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. 10 Full Copyright Statement Copyright (C) The Internet Society 2003. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. Daboo Expires April 2004 [Page 8] Internet Draft SIEVE Include Extension October 2003 The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. 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