Internet DRAFT - draft-murchison-sieve-processimip
draft-murchison-sieve-processimip
Network Working Group K. Murchison
Internet-Draft R. Signes
Intended status: Experimental M. Horsfall
Expires: 28 August 2022 Fastmail
24 February 2022
Sieve Email Filtering: Extension for Processing iMIP Messages
draft-murchison-sieve-processimip-00
Abstract
This document describes the "processimip" extension to the Sieve
email filtering language. The "processimip" extension gives Sieve
the ability to process messages using the iCalendar Message-Based
Interoperability Protocol (iMIP).
Open Issues
1. The Cyrus implementation used at Fastmail also adds an
:invitesonly option to the processimip action in order to emulate
existing functionality elsewhere within our stack. Is there any
interest in formalizing this option? This may be superfluous as
it might not make sense to auto-process an initial invitation but
then NOT auto-process future updates to an event.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 28 August 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Capability Identifier . . . . . . . . . . . . . . . . . . . . 3
4. Process iMIP Action . . . . . . . . . . . . . . . . . . . . . 3
4.1. Addresses Argument . . . . . . . . . . . . . . . . . . . 4
4.2. Updates Only Argument . . . . . . . . . . . . . . . . . . 4
4.3. Calendar ID Argument . . . . . . . . . . . . . . . . . . 4
4.4. Delete Canceled Argument . . . . . . . . . . . . . . . . 4
4.5. Outcome Argument . . . . . . . . . . . . . . . . . . . . 5
4.6. Error String Argument . . . . . . . . . . . . . . . . . . 5
4.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Implementation Status . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8.1. Registration of Sieve Extension . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Users typically receive invites, replies, and cancelations for
events, tasks, etc. via Internet mail messages. It is sometimes
desirable to have such messages automatically parsed and the attached
iCalendar [RFC5545] objects added to, updated on, or deleted from the
user's calendars.
This document defines an extension to the Sieve language [RFC5228]
that enables scripts to process messages using the iCalendar
Message-Based Interoperability Protocol (iMIP) [RFC6047].
Specifically, this extension provides the ability to alter iCalendar
objects on a user's calendars referenced in iMIP messages.
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2. Conventions Used in This Document
Conventions for notations are as in Section 1.1 of [RFC5228],
including use of the "Usage:" label for the definition of action and
tagged arguments syntax.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Capability Identifier
Sieve interpreters that implement this extension have an identifier
of "processimip" for use with the capability mechanism.
4. Process iMIP Action
Usage: processimip [ :addresses <string-list> ]
[ :updatesonly | :calendarid <string> ]
[ :deletecanceled ]
[ :outcome <variablename: string> ]
[ :errstr <variablename: string> ]
The "processimip" action can be used with or without the "variables"
[RFC5229] extension. When the "variables" extension is enabled in a
script using <require "variables">, the script can use the ":outcome"
(Section 4.5) and ":errstr" (Section 4.6) arguments to the
"processimip" action described below. When the "variables" extension
is not enabled, the ":outcome" and ":errstr" arguments MUST NOT be
used and MUST cause an error according to [RFC5228].
"processimip" MUST NOT process a message unless it is a well-formed
iMIP message and one of the recipient user's email addresses matches
the Calendar User Address (see Section 3.3.3 of [RFC5545]) of the
intended target of the message, as determined by the iTIP method (see
Section 1.4 of [RFC5546]) of the message:
"REPLY": Value of the "Organizer" property (see Section 3.8.4.1 of
[RFC5545])
"REQUEST", "CANCEL", "ADD": Value of one of the "Attendee"
properties (see Section 3.8.4.3 of [RFC5545])
The recipient user's email address matches the Calender User Address
of the target if the Calendar User Address is in the form of a mailto
URI and the email address matches the "addr-spec" of the URI.
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An email address is considered to belong to the recipient if it is
one of:
1. an email address known by the implementation to be associated
with the recipient,
2. the final envelope recipient address if it's available to the
implementation, or
3. an address specified by the script writer via the :addresses
(Section 4.1) argument.
The "processimip" action does not cancel the implicit keep.
4.1. Addresses Argument
The optional :addresses argument is used to specify email addresses
that belong to the recipient in addition to the addresses known to
the implementation.
4.2. Updates Only Argument
The optional :updatesonly argument is used to limit the messages
processed to those targeting existing iCalendar objects only. If the
message contains a new iCalendar object (initial invitation), the
implementation MUST NOT add the object to a calendar.
If :updatesonly is omitted, new iCalendar objects (initial
invitations) may be added to one of the user's calendars.
4.3. Calendar ID Argument
The optional :calendarid argument specifies the identifier of the
calendar onto which new iCalendar objects (initial invitations)
should placed.
If :calendarid is omitted, new iCalendar objects will be placed on
the user's "default" calendar as determined by the implementation.
4.4. Delete Canceled Argument
The optional :deletecanceled argument is used to tell the
implementation that if it receives a cancelation message, it should
remove the associated iCalendar object from the calendar.
If :deletecanceled is omitted, the associated iCalendar object will
be marked as canceled and will remain on the calendar.
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4.5. Outcome Argument
The optional :outcome argument specifies the name of a variable into
which one of the following strings specifying the outcome of the
action will be stored:
* "no_action": No action was performed (E.g., the message wasn't an
iMIP message, or the message contained a new iCalendar object but
the ":updatesonly" argument was used)
* "added": A new iCalendar object was added to a calendar
* "update": An iCalendar resource was updated or canceled
* "error": An error processing the iMIP message occurred
4.6. Error String Argument
The optional :errstr argument specifies the name of a variable into
which a string describing the reason for the outcome will be stored.
4.7. Examples
TODO: Actually add examples.
5. Implementation Status
< RFC Editor: before publication please remove this section and the
reference to [RFC7942] >
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
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According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
5.1. Cyrus Server
The open source Cyrus Server (http://www.cyrusimap.org/) project is a
highly scalable enterprise mail system which supports Sieve email
filtering at the point of final delivery. This production level
Sieve implementation supports all of the requirements described in
this document. This implementation is freely distributable under a
BSD style license from Computing Services at Carnegie Mellon
University (http://www.cmu.edu/computing/).
6. Security Considerations
Security considerations are discussed in [RFC5228].
TODO: Discuss calendar SPAM.
7. Privacy Considerations
It is believed that this extension doesn't introduce any privacy
considerations beyond those in [RFC5228].
8. IANA Considerations
8.1. Registration of Sieve Extension
This document defines the following new Sieve extension to be added
to the registry defined in Section 6.2 of [RFC5228] and located here:
https://www.iana.org/assignments/sieve-extensions/sieve-
extensions.xhtml#sieve-extensions
IANA are requested to add a capability to the Sieve Extensions
registry:
To: iana@iana.org
Subject: Registration of new Sieve extension
Capability name: processimip
Description: Adds the "processimip" action command to add and
update iCalendar objects on a user's calendars.
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RFC number: RFC XXXX
Contact address: The Sieve discussion list <sieve@ietf.org>
9. Acknowledgments
The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Ned Freed and Alexey Melnikov.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5228] Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email
Filtering Language", RFC 5228, DOI 10.17487/RFC5228,
January 2008, <https://www.rfc-editor.org/info/rfc5228>.
[RFC5229] Homme, K., "Sieve Email Filtering: Variables Extension",
RFC 5229, DOI 10.17487/RFC5229, January 2008,
<https://www.rfc-editor.org/info/rfc5229>.
[RFC6047] Melnikov, A., Ed., "iCalendar Message-Based
Interoperability Protocol (iMIP)", RFC 6047,
DOI 10.17487/RFC6047, December 2010,
<https://www.rfc-editor.org/info/rfc6047>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
DOI 10.17487/RFC5546, December 2009,
<https://www.rfc-editor.org/info/rfc5546>.
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[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
Authors' Addresses
Kenneth Murchison
Fastmail US LLC
1429 Walnut Street - Suite 1201
Philadelphia, PA 19102
United States of America
Email: murch@fastmailteam.com
Ricardo Signes
Fastmail US LLC
1429 Walnut Street - Suite 1201
Philadelphia, PA 19102
United States of America
Email: rjbs@fastmailteam.com
Matthew Horsfall
Fastmail US LLC
1429 Walnut Street - Suite 1201
Philadelphia, PA 19102
United States of America
Email: alh@fastmailteam.com
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