SieveNetwork Working Group W. SegmullerInternet-DraftRequest for Comments: 5231 B. Leiba Obsoletes: 3431(if approved)IBM T.J. Watson Research CenterExpires: June 30, 2006 December 27, 2005Category: Standards Track January 2008 SieveExtension:Email Filtering: RelationalTests draft-ietf-sieve-3431bis-04Extension Status ofthisThis MemoBy 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 ofThis document specifies an Internet standards track protocol for the InternetEngineering Task Force (IETF), its areas,community, andits working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents validrequests discussion and suggestions fora maximumimprovements. Please refer to the current edition ofsix monthsthe "Internet Official Protocol Standards" (STD 1) for the standardization state andmay 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 liststatus ofcurrent Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The listthis protocol. Distribution ofInternet-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).this memo is unlimited. 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.NoteThis documentis intended to be an update to the existing "relational" extension to the Sieve mail filtering language, available from theobsoletes RFCrepository 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/.3431. Table of Contents 1.Conventions used in this documentIntroduction . . . . . . . . . . . . . .3 2. Introduction. . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . .42 3. Comparators . . . . . . . . . . . . . . . . . . . . . . . . .5. 2 4. Match Types . . . . . . . . . . . . . . . . . . . . . . . . .6 4.1. 3 4.1. Match Type VALUE . . . . . . . . . . . . . . . . . . . . .. . 6 4.23 4.2. Match Type COUNT . . . . . . . . . . . . . . . . . . . . .. . 63 5. InteractionWithwith Other Sieve Actions . . . . . . . . . . . . .84 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . .9. 4 7. Extended Example . . . . . . . . . . . . . . . . . . . . . . .106 8. ChangesSincesince RFC 3431 . . . . . . . . . . . . . . . . . . . .116 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . .12. 7 10. Security Considerations . . . . . . . . . . . . . . . . . . .13. 7 11. Normative References . . . . . . . . . . . . . . . . . . . . .13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 157 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]. 2. IntroductionIntroduction 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 recipientfield. For example: arefield, for example, whether there are more than 5 addresses in the to and cc fields. The capability string associated with the extension defined in this document is "relational". 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, RFC 2119. Conventions for notations are as in [Sieve] section 1.1, including the use of [Kwds] and the use of [ABNF]. 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],[RFC4790], MUST be supported for any implementation of this extension. The comparator "i;ascii-numeric" MUST support at least32 bit32-bit unsigned integers. Larger integers MAY be supported. Note: the "i;ascii-numeric" comparator does not support negative numbers. 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 "!=".4.14.1. Match Type VALUE The VALUE match type does a relational comparison between strings. The VALUE match type may be used with any comparatorwhichthat 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.4.24.2. 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 definedbelowbelow, 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. 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.ThereUsing this test, there is no way a Sieve script can determine if the message was actually sent to someoneelse using this test.else. 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 COUNTtest,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". 5. InteractionWithwith 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. 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 totruetrue, 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. 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"; } 8. ChangesSincesince 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 fromACAPthe Application Configuration Access Protocol (ACAP) to the "Internet Application Protocol Collation Registry"document.document [RFC4790]. 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. 9. IANA ConsiderationsThis document requests thatThe following template specifies the IANAupdate the entry forregistration of the"relational"relational Sieve extensionto point tospecified in thisdocument.document: To: iana@iana.org Subject: Registration of new Sieve extension Capability name: relational Description: Extends existing conditional tests in Sieve language to allow relational operators RFC number: RFC 5231 Contact address: The Sieve discussion list <ietf-mta-filters@imc.org> 10. Security Considerations An implementation MUST ensure that the test for envelope "to" only reflects the delivery to the current user.ItUsing this test, it MUST not be possible for a user to determine if this message was delivered to someoneelse using this test.else. 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. [RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet Application Protocol Collation Registry", RFC 4790, March 2007. [Sieve] Guenther,P.P., Ed. and T. Showalter, Ed., "Sieve: An Email Filtering Language",work in progress, draft-ietf-sieve-3028bis, July 2005.RFC 5228, January 2008. Authors' Addresses Wolfgang Segmuller IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7408Email:EMail: werewolf@us.ibm.com Barry Leiba IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7941Email:EMail: leiba@watson.ibm.com Full Copyright Statement Copyright (C) The IETF Trust (2008). 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