I have implemented a regular expression extension to CMU Sieve, which
I'm told will be included in the upcoming version of Cyrus Imapd. In
order to promote some discussion on a possible specification for this
extension, I have written a *very* rough draft as a starting point.
An issue which I encountered while implementing the code is that of
escaped meta-characters. Should they be single-escaped (ie, "\+") or
double-escaped (ie, "\\+")? Section 2.4.2 of [SIEVE] is sort of vague
on this topic, only saying that "Other escape sequences may be permitted
depending on context."
CMU Sieve currently strips all single backslashes in quoted strings,
which seems to be one reasonable implementation based on the working in
the spec. This behavior requires that any escaped meta-character in a
regex must be preceded by two backslashes. This behavior also effects
the :matches match-type in the base spec and imapflags as defined in
draft-melnikov-sieve-imapflags-02.
I am not up to speed on the discussions that led to the current wording
in the spec, but I'd like to see all escape sequences passed through
untouched, or perhaps be context-sensitive as hinted at in the spec.
But, "this is just my opinion, and I could be wrong."
Regards,
Ken
--
Kenneth Murchison Oceana Matrix Ltd.
Software Engineer 21 Princeton Place
716-662-8973 x26 Orchard Park, NY 14127
--PGP Public Key-- http://www.oceana.com/~ken/ksm.pgp
Network Working Group Ken Murchison
Document: draft-murchison-sieve-regex-00.txt Oceana Matrix Ltd.
Expires August 14, 2000 9 February 2000
Sieve -- Regular Expression 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
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Internet-Drafts are draft documents valid for a maximum of six
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To view the list Internet-Draft Shadow Directories, see
http://www.ietf.org/shadow.html.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society 2000. All Rights Reserved.
Abstract
In some cases, it is desireable to have a string matching mechanism
which is more powerful than a simple exact match, a substring match
or a glob-style wildcard match. The regular expression matching
mechanism defined in this draft should allow users to isolate just
about any string or address in a message header or envelope.
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Internet Draft Sieve -- Regex Extension February 9, 2000
Tablee of Contents
Status of this Memo . . . . . . . . . . . . . . . . . . . . . . . . 1
Copyright Notice . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Capability Identifier . . . . . . . . . . . . . . . . . . . . 3
3. Regex Match Type . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 3
6. Author's Address . . . . . . . . . . . . . . . . . . . . . . 3
Appendix A. References . . . . . . . . . . . . . . . . . . . . . . 4
Appendix B. Full Copyright Statement . . . . . . . . . . . . . . . 4
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Internet Draft Sieve -- Regex Extension February 9, 2000
1. Introduction
This is an extension to the Sieve language defined by [SIEVE] for
comparing strings to regular expressions.
Conventions for notations are as in [SIEVE] section 1.1, including
use of [KEYWORDS].
2. Capability Identifier
The capability string associated with the extension defined in this
document is "regex".
3. Regex Match Type
Commands that support matching may take the optional tagged argument
":regex" to specify that a regular expression match should be
performed. The ":regex" match type is subject to the same rules and
restrictions as the standard match types defined in [SIEVE].
The ":regex" match type is compatible with both the "i;octet" and
"i;ascii-casemap" comparators and may be used with them.
Implementations MUST support extended ("modern") regular expressions
as defined by [POSIX.2] Any regular expression not defined by
[POSIX.2], including [POSIX.2] basic ("obsolete") regular
expressions are not supported by this extension.
4. Security Considerations
Security considerations are discussed in [SIEVE]. It is believed
that this extension doesn't introduce any additional security
concerns.
5. Acknowledgments
Thanks to ??? for help with this document.
6. Author's Address
Ken Murchison
Oceana Matrix Ltd.
21 Princeton Place
Orchard Park, NY 14127
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Internet Draft Sieve -- Regex Extension February 9, 2000
Phone: (716) 662-8973
EMail: ken(_at_)oceana(_dot_)com
Appendix A. References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", Harvard University, RFC 2119, March, 1997.
[SIEVE] Showalter, T., "Sieve: A Mail Filtering Language", Mira-
point, Inc., Work In Progress.
[POSIX.2], "Portable Operating System Interface (POSIX). Part 2,
Shell and utilities", National Institute of Standards and Tech-
nology (U.S.).
Appendix B. Full Copyright Statement
Copyright (C) The Internet Society 2000. 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 develop-
ing 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.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS 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.
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