Sieve Working Group W. Segmuller Internet-Draft B. Leiba Obsoletes: 3431 (if approved) IBM T.J. Watson Research Center Expires: June 30, 2006 December 27, 2005 Sieve Extension: Relational Tests draft-ietf-sieve-3431bis-04 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 June 30, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document describes the RELATIONAL extension to the Sieve mail filtering language defined in RFC 3028. This extension extends existing conditional tests in Sieve to allow relational operators. In addition to testing their content, it also allows for testing of the number of entities in header and envelope fields. Note Segmuller & Leiba Expires June 30, 2006 [Page 1]
Internet-Draft Sieve Extension: Relational Tests December 2005 This document is intended to be an update to the existing "relational" extension to the Sieve mail filtering language, available from the RFC repository as ftp://ftp.isi.edu/in-notes/rfc3431.txt. This document and the Sieve language itself are being discussed on the MTA Filters mailing list at mailto:ietf-mta-filters@imc.org. Subscription requests can be sent to mailto:ietf-mta-filters-request@imc.org?body=subscribe (send an email message with the word "subscribe" in the body). More information on the mailing list along with a WWW archive of back messages is available at http://www.imc.org/ietf-mta-filters/. Table of Contents 1. Conventions used in this document . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Comparators . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Match Types . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1 Match Type VALUE . . . . . . . . . . . . . . . . . . . . . . . 6 4.2 Match Type COUNT . . . . . . . . . . . . . . . . . . . . . . . 6 5. Interaction With Other Sieve Actions . . . . . . . . . . . . . 8 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. Extended Example . . . . . . . . . . . . . . . . . . . . . . . 10 8. Changes Since RFC 3431 . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 11. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 15 Segmuller & Leiba Expires June 30, 2006 [Page 2]
Internet-Draft Sieve Extension: Relational Tests December 2005 1. 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, RFC 2119. Conventions for notations are as in [Sieve] section 1.1, including the use of [Kwds] and the use of [ABNF]. Segmuller & Leiba Expires June 30, 2006 [Page 3]
Internet-Draft Sieve Extension: Relational Tests December 2005 2. Introduction The RELATIONAL extension to the Sieve mail filtering language [Sieve] provides relational operators on the address, envelope, and header tests. This extension also provides a way of counting the entities in a message header or address field. With this extension, the Sieve script may now determine if a field is greater than or less than a value instead of just equivalent. One use is for the x-priority field: move messages with a priority greater than 3 to the "work on later" folder. Mail could also be sorted by the from address. Those userids that start with 'a'-'m' go to one folder, and the rest go to another folder. The Sieve script can also determine the number of fields in the header, or the number of addresses in a recipient field. For example: are there more than 5 addresses in the to and cc fields. The capability string associated with the extension defined in this document is "relational". Segmuller & Leiba Expires June 30, 2006 [Page 4]
Internet-Draft Sieve Extension: Relational Tests December 2005 3. Comparators This document does not define any comparators or exempt any comparators from the require clause. Any comparator used must be treated as defined in [Sieve]. The "i;ascii-numeric" comparator, as defined in [Comp], MUST be supported for any implementation of this extension. The comparator "i;ascii-numeric" MUST support at least 32 bit unsigned integers. Larger integers MAY be supported. Note: the "i;ascii-numeric" comparator does not support negative numbers. Segmuller & Leiba Expires June 30, 2006 [Page 5]
Internet-Draft Sieve Extension: Relational Tests December 2005 4. Match Types This document defines two new match types. They are the VALUE match type and the COUNT match type. The syntax is: MATCH-TYPE =/ COUNT / VALUE COUNT = ":count" relational-match VALUE = ":value" relational-match relational-match = DQUOTE ("gt" / "ge" / "lt" / "le" / "eq" / "ne") DQUOTE ; "gt" means "greater than", the C operator ">". ; "ge" means "greater than or equal", the C operator ">=". ; "lt" means "less than", the C operator "<". ; "le" means "less than or equal", the C operator "<=". ; "eq" means "equal to", the C operator "==". ; "ne" means "not equal to", the C operator "!=". 4.1 Match Type VALUE The VALUE match type does a relational comparison between strings. The VALUE match type may be used with any comparator which returns sort information. A value from the message is considered the left side of the relation. A value from the test expression, the key-list for address, envelope, and header tests, is the right side of the relation. If there are multiple values on either side or both sides, the test is considered true if any pair is true. 4.2 Match Type COUNT The COUNT match type first determines the number of the specified entities in the message and does a relational comparison of the number of entities, as defined below to the values specified in the test expression. The COUNT match type SHOULD only be used with numeric comparators. The Address Test counts the number of addresses (the number of "mailbox" elements, as defined in [RFC2822]) in the specified fields. Segmuller & Leiba Expires June 30, 2006 [Page 6]
Internet-Draft Sieve Extension: Relational Tests December 2005 Group names are ignored, but the contained mailboxes are counted. The Envelope Test counts the number of addresses in the specified envelope parts. The envelope "to" will always have only one entry, which is the address of the user for whom the Sieve script is running. There is no way a Sieve script can determine if the message was actually sent to someone else using this test. The envelope "from" will be 0 if the MAIL FROM is empty, or 1 if MAIL FROM is not empty. The Header Test counts the total number of instances of the specified fields. This does not count individual addresses in the "to", "cc", and other recipient fields. In all cases, if more than one field name is specified, the counts for all specified fields are added together to obtain the number for comparison. Thus, specifying ["to", "cc"] in an address COUNT test, compares the total number of "to" and "cc" addresses; if separate counts are desired, they must be done in two comparisons, perhaps joined by "allof" or "anyof". Segmuller & Leiba Expires June 30, 2006 [Page 7]
Internet-Draft Sieve Extension: Relational Tests December 2005 5. Interaction With Other Sieve Actions This specification adds two match types. The VALUE match type only works with comparators that return sort information. The COUNT match type only makes sense with numeric comparators. There is no interaction with any other Sieve operations, nor with any known extensions. In particular, this specification has no effect on implicit KEEP, nor on any explicit message actions. Segmuller & Leiba Expires June 30, 2006 [Page 8]
Internet-Draft Sieve Extension: Relational Tests December 2005 6. Example Using the message: received: ... received: ... subject: example to: foo@example.com, baz@example.com cc: qux@example.com The test: address :count "ge" :comparator "i;ascii-numeric" ["to", "cc"] ["3"] would evaluate to true and the test anyof ( address :count "ge" :comparator "i;ascii-numeric" ["to"] ["3"], address :count "ge" :comparator "i;ascii-numeric" ["cc"] ["3"] ) would evaluate to false. To check the number of received fields in the header, the following test may be used: header :count "ge" :comparator "i;ascii-numeric" ["received"] ["3"] This would evaluate to false. But header :count "ge" :comparator "i;ascii-numeric" ["received", "subject"] ["3"] would evaluate to true. The test: header :count "ge" :comparator "i;ascii-numeric" ["to", "cc"] ["3"] will always evaluate to false on an RFC 2822 compliant message [RFC2822], since a message can have at most one "to" field and at most one "cc" field. This test counts the number of fields, not the number of addresses. Segmuller & Leiba Expires June 30, 2006 [Page 9]
Internet-Draft Sieve Extension: Relational Tests December 2005 7. Extended Example require ["relational", "comparator-i;ascii-numeric", "fileinto"]; if header :value "lt" :comparator "i;ascii-numeric" ["x-priority"] ["3"] { fileinto "Priority"; } elsif address :count "gt" :comparator "i;ascii-numeric" ["to"] ["5"] { # everything with more than 5 recipients in the "to" field # is considered SPAM fileinto "SPAM"; } elsif address :value "gt" :all :comparator "i;ascii-casemap" ["from"] ["M"] { fileinto "From N-Z"; } else { fileinto "From A-M"; } if allof ( address :count "eq" :comparator "i;ascii-numeric" ["to", "cc"] ["1"] , address :all :comparator "i;ascii-casemap" ["to", "cc"] ["me@foo.example.com"] ) { fileinto "Only me"; } Segmuller & Leiba Expires June 30, 2006 [Page 10]
Internet-Draft Sieve Extension: Relational Tests December 2005 8. Changes Since RFC 3431 Apart from several minor editorial/wording changes, the following list describes the notable changes to this specification since RFC 3431. o Updated references, including changing the comparator reference from ACAP to the "Internet Application Protocol Collation Registry" document. o Updated and corrected the examples. o Added definition comments to ABNF for "gt", "lt", etc. o Clarified what RFC 2822 elements are counted in the COUNT test. o Removed the requirement to strip white space from header fields before comparing; a more general version of this requirement has been added to the Sieve base spec. Segmuller & Leiba Expires June 30, 2006 [Page 11]
Internet-Draft Sieve Extension: Relational Tests December 2005 9. IANA Considerations This document requests that the IANA update the entry for the "relational" Sieve extension to point to this document. Segmuller & Leiba Expires June 30, 2006 [Page 12]
Internet-Draft Sieve Extension: Relational Tests December 2005 10. Security Considerations An implementation MUST ensure that the test for envelope "to" only reflects the delivery to the current user. It MUST not be possible for a user to determine if this message was delivered to someone else using this test. Additional security considerations are discussed in [Sieve]. 11. Normative References [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. [Comp] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet Application Protocol Collation Registry", work in progress, draft-newman-i18n-comparator, September 2005. [Kwds] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [Sieve] Guenther, P. and T. Showalter, "Sieve: An Email Filtering Language", work in progress, draft-ietf-sieve-3028bis, July 2005. Authors' Addresses Wolfgang Segmuller IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7408 Email: werewolf@us.ibm.com Segmuller & Leiba Expires June 30, 2006 [Page 13]
Internet-Draft Sieve Extension: Relational Tests December 2005 Barry Leiba IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7941 Email: leiba@watson.ibm.com Segmuller & Leiba Expires June 30, 2006 [Page 14]
Internet-Draft Sieve Extension: Relational Tests December 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. 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. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Segmuller & Leiba Expires June 30, 2006 [Page 15]
