draft-ietf-sieve-external-lists-04.txt   draft-ietf-sieve-external-lists-05.txt 
Sieve Working Group A. Melnikov Sieve Working Group A. Melnikov
Internet-Draft Isode Limited Internet-Draft Isode Limited
Intended status: Standards Track B. Leiba Intended status: Standards Track B. Leiba
Expires: May 12, 2011 Huawei Technologies Expires: September 2, 2011 Huawei Technologies
November 8, 2010 March 1, 2011
Sieve Extension: Externally Stored Lists Sieve Extension: Externally Stored Lists
draft-ietf-sieve-external-lists-04 draft-ietf-sieve-external-lists-05
Abstract Abstract
The Sieve scripting language can be used to implement whitelisting, The Sieve scripting language can be used to implement whitelisting,
blacklisting, personal distribution lists, and other sorts of list blacklisting, personal distribution lists, and other sorts of list
matching. Currently, this requires that all members of such lists be matching. Currently, this requires that all members of such lists be
hardcoded in the script itself. Whenever a member of a list is added hardcoded in the script itself. Whenever a member of a list is added
or deleted, the script needs to be updated and possibly uploaded to a or deleted, the script needs to be updated and possibly uploaded to a
mail server. mail server.
This document defines a Sieve extension for accessing externally This document defines a Sieve extension for accessing externally
stored lists -- lists whose members are stored externally to the stored lists -- lists whose members are stored externally to the
script, such as using LDAP (RFC 4510), ACAP (RFC 2244), or relational script, such as using LDAP (RFC 4510), ACAP (RFC 2244), or relational
databases. databases.
ToDo ToDo
o Do we need support for URI schemes in ihave? From IETF 77
minutes: "Can use ihave to test if a URI is valid, both that the
scheme is supported and that the URI can be retrieved/queried."
o Do we need to say anything about comparators? We can be silent
(as now), we can say that comparators MAY be ignored as a list-
specific thing, or we can say that comparators MUST NOT be used.
o Should we add a mandatory-to-implement tag? Ned suggests (and I o Should we add a mandatory-to-implement tag? Ned suggests (and I
agree) that it might be good to add a registry of well-defined agree) that it might be good to add a registry of well-defined
strings that can be used instead of URIs, and define the initial strings that can be used instead of URIs, and define the initial
string "pab" to represent the user's personal address book. string "ab" to represent the user's personal address book.
o Do we want to have the :list test set variables? See Ned's
comments in the text.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 12, 2011. This Internet-Draft will expire on September 2, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 3, line 16 skipping to change at page 3, line 16
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conventions used in this document . . . . . . . . . . . . 4 1.1. Conventions used in this document . . . . . . . . . . . . 4
2. Extlists extension . . . . . . . . . . . . . . . . . . . . 4 2. Extlists extension . . . . . . . . . . . . . . . . . . . . 4
2.1. Capability Identifier . . . . . . . . . . . . . . . . . . 4 2.1. Capability Identifier . . . . . . . . . . . . . . . . . . 4
2.2. :list match type for supported tests . . . . . . . . . . . 4 2.2. :list match type for supported tests . . . . . . . . . . . 4
2.3. :list tagged argument to the "redirect" action . . . . . . 5 2.3. :list tagged argument to the "redirect" action . . . . . . 5
2.4. Other uses for external lists . . . . . . . . . . . . . . 6 2.4. Other uses for external lists . . . . . . . . . . . . . . 6
2.5. Syntax of an externally stored list name . . . . . . . . . 6 2.5. Syntax of an externally stored list name . . . . . . . . . 6
2.6. Interaction with ManageSieve . . . . . . . . . . . . . . . 6 2.6. Test valid_ext_list . . . . . . . . . . . . . . . . . . . 7
2.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.7. Interaction with ManageSieve . . . . . . . . . . . . . . . 7
2.7.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 7 2.8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.7.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 7 2.8.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 7
2.7.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . . . 7 2.8.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 8
2.8.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Security Considerations . . . . . . . . . . . . . . . . . 8 3. Security Considerations . . . . . . . . . . . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . 10
4.1. Registration of Sieve extension . . . . . . . . . . . . . 9 4.1. Registration of Sieve extension . . . . . . . . . . . . . 10
4.2. Registration of ManageSieve capability . . . . . . . . . . 9 4.2. Registration of ManageSieve capability . . . . . . . . . . 10
4.3. Registration of a new URI scheme . . . . . . . . . . . . . 10
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 10 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 11
6. References . . . . . . . . . . . . . . . . . . . . . . . . 10 6. References . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Normative References . . . . . . . . . . . . . . . . . . . 10 6.1. Normative References . . . . . . . . . . . . . . . . . . . 11
6.2. Informative References . . . . . . . . . . . . . . . . . . 10 6.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
This document specifies an extension to the Sieve language [RFC5228] This document specifies an extension to the Sieve language [RFC5228]
for checking membership in an external list or for redirecting for checking membership in an external list or for redirecting
messages to an external list of recipients. An "external list" is a messages to an external list of recipients. An "external list" is a
list whose members are stored externally to the Sieve script, such as list whose members are stored externally to the Sieve script, such as
using LDAP [RFC4510], ACAP [RFC2244], or relational databases. using LDAP [RFC4510], ACAP [RFC2244], or relational databases.
This extension adds a new match type to apply to supported tests, and This extension adds a new match type to apply to supported tests, and
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; only valid for supported tests ; only valid for supported tests
The new ":list" match type changes the interpretation of the "key- The new ":list" match type changes the interpretation of the "key-
list" parameter (the second parameter) to supported tests. When the list" parameter (the second parameter) to supported tests. When the
match type is ":list", the key-list becomes a list of names of match type is ":list", the key-list becomes a list of names of
externally stored lists. The external lists are queried, perhaps externally stored lists. The external lists are queried, perhaps
through a list-specific mechanism, and the test evaluates to "true" through a list-specific mechanism, and the test evaluates to "true"
if any of the specified values matches any member of one or more of if any of the specified values matches any member of one or more of
the lists. the lists.
Comparators are not allowed together with the ":list" match type, so
if both are specified in a test, that MUST result in an error.
Implementations MUST support "address", "envelope" and "header" Implementations MUST support "address", "envelope" and "header"
tests. Implementations that include the Variables extension tests. Implementations that include the Variables extension
[RFC5229] MUST also support "string" tests. [RFC5229] MUST also support "string" tests.
Implementations MAY support other tests but MUST raise an error Implementations MAY support other tests but MUST raise an error
(which SHOULD be a compile-time error, but MAY be a runtime error) (which SHOULD be a compile-time error, but MAY be a runtime error)
when a script uses :list with a test for which it is not supported. when a script uses :list with a test for which it is not supported.
To maintain interoperability, other tests that can be used with :list To maintain interoperability, other tests that can be used with :list
SHOULD be documented in a specification that defines a capability SHOULD be documented in a specification that defines a capability
string that can be tested (in a "require" statement, or using ihave string that can be tested (in a "require" statement, or using ihave
[RFC5463]). [RFC5463]).
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[RFC5229] MUST also support "string" tests. [RFC5229] MUST also support "string" tests.
Implementations MAY support other tests but MUST raise an error Implementations MAY support other tests but MUST raise an error
(which SHOULD be a compile-time error, but MAY be a runtime error) (which SHOULD be a compile-time error, but MAY be a runtime error)
when a script uses :list with a test for which it is not supported. when a script uses :list with a test for which it is not supported.
To maintain interoperability, other tests that can be used with :list To maintain interoperability, other tests that can be used with :list
SHOULD be documented in a specification that defines a capability SHOULD be documented in a specification that defines a capability
string that can be tested (in a "require" statement, or using ihave string that can be tested (in a "require" statement, or using ihave
[RFC5463]). [RFC5463]).
For example, testing ':header ["to", "cc"]' against a list would For example, testing 'header ["to", "cc"]' against a list would cause
cause each "to" and "cc" value, ignoring leading and trailing each "to" and "cc" value, ignoring leading and trailing whitespace,
whitespace, to be queried. If any value is found to belong to the to be queried. If any value is found to belong to the list, the test
list, the test returns "true". If no value belongs to the list, the returns "true". If no value belongs to the list, the test returns
test returns "false". Once a value is found in the list, there is no "false". Once a value is found in the list, there is no need for the
need for the query mechanism to look further. query mechanism to look further.
For some lists, the Sieve engine might directly retrieve the list and For some lists, the Sieve engine might directly retrieve the list and
make its own comparison. Other lists might not work that way -- they make its own comparison. Other lists might not work that way -- they
might provide a way to ask if a value is in the list, but not permit might provide a way to ask if a value is in the list, but not permit
retrieval of the list itself. It is up to the Sieve implementation retrieval of the list itself. It is up to the Sieve implementation
to understand how to interact with any supported list. If the Sieve to understand how to interact with any supported list. If the Sieve
engine is permanently unable to query the list (perhaps because the engine is permanently unable to query the list (perhaps because the
list doesn't support the required operation), the test MUST result in list doesn't support the required operation), the test MUST result in
a runtime error in the Sieve script. a runtime error in the Sieve script.
See Section 2.5 for the detailed description of syntax used for See Section 2.5 for the detailed description of syntax used for
naming externally stored lists. naming externally stored lists.
[[anchor4: Ned: There's one addition I'd like to make to the list.
I've proposed saying that if variables are enabled ${0} should return
the thing that matched in a :list match, just like it does for
:matches. ${1} and so on would return optional, list-specific
information. In the case of pab: URLs I'd suggest defining ${1} to
be a sort of status for the entry returned.]]
[[anchor5: Alexey: Can you elaborate on what you mean by "status"
here and how would this work for other types of URIs?]]
2.3. :list tagged argument to the "redirect" action 2.3. :list tagged argument to the "redirect" action
Usage: redirect :list <ext-list-name: string> Usage: redirect :list <ext-list-name: string>
The "redirect" action with the ":list" argument is used to send the The "redirect" action with the ":list" argument is used to send the
message to one or more email addresses stored in the externally message to one or more email addresses stored in the externally
stored list 'ext-list-name'. This variant of the redirect command stored list 'ext-list-name'. This variant of the redirect command
can be used to implement a personal distribution list. can be used to implement a personal distribution list.
For this feature to work, one of the following conditions has to be For this feature to work, one of the following conditions has to be
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lists, using other Sieve features, might be devised in the future, lists, using other Sieve features, might be devised in the future,
and such uses can be described in extensions to this document. and such uses can be described in extensions to this document.
2.5. Syntax of an externally stored list name 2.5. Syntax of an externally stored list name
A name of an externally stored list is always an absolute URI A name of an externally stored list is always an absolute URI
[RFC3986]. Implementations might find URIs such as LDAP [RFC4510], [RFC3986]. Implementations might find URIs such as LDAP [RFC4510],
CardDAV [I-D.ietf-vcarddav-carddav], or Tag [RFC4151] to be useful CardDAV [I-D.ietf-vcarddav-carddav], or Tag [RFC4151] to be useful
for naming external lists. for naming external lists.
[[anchor7: This might have to change with the introduction of "ab:"
URIs]]
The "tag" URI scheme [RFC4151] MUST be supported, and can be used to The "tag" URI scheme [RFC4151] MUST be supported, and can be used to
represent opaque, but user friendlier identifiers. Resolution of represent opaque, but user friendlier identifiers. Resolution of
such identifiers is going to be implementation specific and it can such identifiers is going to be implementation specific and it can
help in hiding the complexity of an implementation from end users. help in hiding the complexity of an implementation from end users.
For example, an implementation can provide a web interface for For example, an implementation can provide a web interface for
managing lists of users stored in LDAP. Requiring users to know managing lists of users stored in LDAP. Requiring users to know
generic LDAP URI syntax might not be very practical, due to its generic LDAP URI syntax might not be very practical, due to its
complexity. An implementation can instead use a fixed tag URI prefix complexity. An implementation can instead use a fixed tag URI prefix
such as "tag:example.com,<date>:" (where <date> can be, for example, such as "tag:example.com,<date>:" (where <date> can be, for example,
a date generated once on installation of the web interface and left a date generated once on installation of the web interface and left
untouched upon upgrades) and the prefix doesn't even need to be shown untouched upon upgrades) and the prefix doesn't even need to be shown
to end users. to end users.
2.6. Interaction with ManageSieve 2.6. Test valid_ext_list
Usage: valid_ext_list <ext-list-names: string-list>
The "valid_ext_list" test is true if all of the external list names
in the ext-list-names argument are supported, and they are valid both
syntactically (including URI parameters) and semantically (including
implementation-specific semantic restrictions). Otherwise the test
returns false.
This test MUST perform exactly the same validation of an external
list name as would be performed by the "header :list" test.
2.7. Interaction with ManageSieve
This extension defines the following new capability for ManageSieve This extension defines the following new capability for ManageSieve
(see [RFC5804] section 1.7): (see [RFC5804] section 1.7):
EXTLISTS - A space-separated list of URI schema parts [RFC3986] for EXTLISTS - A space-separated list of URI schema parts [RFC3986] for
supported externally stored list types. This capability MUST be supported externally stored list types. This capability MUST be
returned if the Sieve implementation supports the "extlists" returned if the corresponding Sieve implementation supports the
extension defined in this document. "extlists" extension defined in this document.
This also extends the ManageSieve ABNF as follows: This also extends the ManageSieve ABNF as follows:
single-capability =/ DQUOTE "EXTLISTS" DQUOTE SP ext-list-types CRLF single-capability =/ DQUOTE "EXTLISTS" DQUOTE SP ext-list-types CRLF
; single-capability is defined in [RFC5804] ; single-capability is defined in [RFC5804]
ext-list-types = string ext-list-types = string
; space separated list of URI schema parts ; space separated list of URI schema parts
; for supported externally stored list types. ; for supported externally stored list types.
; MUST NOT be empty. ; MUST NOT be empty.
2.7. Examples 2.8. Examples
2.7.1. Example 1 2.8.1. Example 1
This example uses the "envelope" option [RFC5228] and the This example uses the "envelope" option [RFC5228] and the
"subaddress" extension [RFC5233]: "subaddress" extension [RFC5233]:
require ["extlists", "envelope", "subaddress"]; require ["extlists", "envelope", "subaddress"];
# Submission from list members is sent to all members # Submission from list members is sent to all members
if allof (envelope :detail :list "to" if allof (envelope :detail :list "to"
"tag:example.com,2009-05-28:mylist", "tag:example.com,2009-05-28:mylist",
header :list "from" header :list "from"
"tag:example.com,2009-05-28:mylist") { "tag:example.com,2009-05-28:mylist") {
redirect :list "tag:example.com,2009-05-28:mylist"; redirect :list "tag:example.com,2009-05-28:mylist";
} }
2.7.2. Example 2 2.8.2. Example 2
This example uses the "currentdate" test [RFC5260] and a list This example uses the "currentdate" test [RFC5260] and a list
containing the dates of local holidays. If today is a holiday, the containing the dates of local holidays. If today is a holiday, the
script will notify [RFC5435] the user via XMPP [RFC5437] about the script will notify [RFC5435] the user via XMPP [RFC5437] about the
message. message.
require ["extlists", "date", "enotify"]; require ["extlists", "date", "enotify"];
if currentdate :list "date" if currentdate :list "date"
"tag:example.com,2010-01-01:localHolidays" { "tag:example.com,2010-01-01:localHolidays" {
notify "xmpp:romeo@im.example.com"; notify "xmpp:romeo@im.example.com";
} }
2.7.3. Example 3 2.8.3. Example 3
This example uses a personal address book, along with spamtest This example uses a personal address book, along with spamtest
[RFC5235] and the relational extension [RFC5231] to give a different [RFC5235] and the relational extension [RFC5231] to give a different
level of spam tolerance to known senders. level of spam tolerance to known senders.
require ["envelope", "extlists", "fileinto", "spamtest", require ["envelope", "extlists", "fileinto", "spamtest",
"relational", "comparator-i;ascii-numeric"]; "relational", "comparator-i;ascii-numeric"];
if allof ( if allof (
envelope :list "from" "tag:example.com,2010-04-10:pab", envelope :list "from" "tag:example.com,2010-04-10:pab",
spamtest :value "ge" :comparator "i;ascii-numeric" "8" spamtest :value "ge" :comparator "i;ascii-numeric" "8"
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4.2. Registration of ManageSieve capability 4.2. Registration of ManageSieve capability
The following requests IANA to register a new ManageSieve Capability The following requests IANA to register a new ManageSieve Capability
according to the IANA registration template specified in [RFC5804]: according to the IANA registration template specified in [RFC5804]:
To: iana@iana.org To: iana@iana.org
Subject: ManageSieve Capability Registration Subject: ManageSieve Capability Registration
Capability name: extlists Capability name: extlists
Description: This capability is returned if the server supports the Description: This capability is returned if the server supports the
"extlists" [RFCXXXX] Sieve extension. "extlists" [RFCXXXX] Sieve extension.
Relevant publications: this RFC, Section 2.6 Relevant publications: this RFC, Section 2.7
Person & email address to contact for further information: Alexey Person & email address to contact for further information: Alexey
Melnikov <alexey.melnikov@isode.com> Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG Author/Change controller: IESG
4.3. Registration of a new URI scheme
The following requests IANA to register a new URI scheme according to
the IANA registration template specified in [RFC4395]:
URI scheme name: ab
Status: Permanent
URI scheme syntax:
paburi = "ab:" addrbook [ "?" extensions ]
addrbook = segment
; <segment> defined in [RFC3986]
extensions = query
; <query> defined in [RFC3986]
URI scheme semantics: "ab" URIs are used for designating references
to personal address books. A personal address book is an internal
concept used by different applications (such as Sieve interpreters)
for describing a list of named entries, and maybe translated into
other types of address books, such as LDAP Groups.
Encoding considerations: Percent-encoding is allowed in "segment" and
"query" components. Internationalization is handled by IRI
processing.
Intended usage: An "ab" URI is designed to be used internally by
applications for referencing address books.
Applications and/or protocols that use this URI scheme name:
Currently only Sieve External List extension is using this URI
scheme. Email clients that use URIs internally might find this URI
scheme to be useful as well.
Interoperability considerations: Applications are only REQUIRED to
support "ab:default".
Security considerations: Applications SHOULD ensure appropriate
restrictions are in place to protect sensitive information that might
be revealed by "ab" URIs from access or modification by untrusted
sources.
Relevant publications: this RFC
Contact: Sieve IETF WG <sieve@ietf.org>
Author/Change controller: IETF/IESG
5. Acknowledgements 5. Acknowledgements
Thanks to Alexandros Vellis, Nigel Swinson, Ned Freed, Kjetil Torgrim Thanks to Alexandros Vellis, Nigel Swinson, Ned Freed, Kjetil Torgrim
Homme, Dave Cridland, Cyrus Daboo, Pete Resnick, and Robert Burrell Homme, Dave Cridland, Cyrus Daboo, Pete Resnick, and Robert Burrell
Donkin for ideas, comments and suggestions. Kristin Hubner also Donkin for ideas, comments and suggestions. Kristin Hubner also
helped greatly with the examples. helped greatly with the examples.
6. References 6. References
6.1. Normative References 6.1. Normative References
skipping to change at page 10, line 36 skipping to change at page 12, line 6
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005. RFC 3986, January 2005.
[RFC4151] Kindberg, T. and S. Hawke, "The 'tag' URI Scheme", [RFC4151] Kindberg, T. and S. Hawke, "The 'tag' URI Scheme",
RFC 4151, October 2005. RFC 4151, October 2005.
[RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
Registration Procedures for New URI Schemes", BCP 35,
RFC 4395, February 2006.
[RFC5228] Guenther, P. and T. Showalter, "Sieve: An Email Filtering [RFC5228] Guenther, P. and T. Showalter, "Sieve: An Email Filtering
Language", RFC 5228, January 2008. Language", RFC 5228, January 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely [RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely
Managing Sieve Scripts", RFC 5804, July 2010. Managing Sieve Scripts", RFC 5804, July 2010.
6.2. Informative References 6.2. Informative References
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