One document matched: draft-ietf-sieve-include-07.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM 'rfc2629.dtd' [
<!ENTITY rfc2119 PUBLIC ''
'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml'>
<!ENTITY rfc5228 PUBLIC ''
'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5228.xml'>
<!ENTITY rfc5229 PUBLIC ''
'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5229.xml'>
<!ENTITY rfc5804 PUBLIC ''
'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5804.xml'>
]>
<?rfc toc="yes" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc ipr='trust200902' docName='draft-ietf-sieve-include-07' category='std'>
<front>
<title abbrev="Sieve Extension: Include">
Sieve Email Filtering: Include Extension
</title>
<author initials='C.' surname='Daboo' fullname='Cyrus Daboo'>
<organization></organization>
<address>
<email>cyrus@daboo.name</email>
</address>
</author>
<author initials='A.' surname='Stone' fullname='Aaron Stone'>
<organization></organization>
<address>
<email>aaron@serendipity.cx</email>
</address>
</author>
<date month='July' year='2011' />
<area>Applications</area>
<abstract>
<t>
The Sieve Email Filtering "include" extension permits users to include
one Sieve script inside another. This can make managing large scripts or
multiple sets of scripts much easier, and allows a site and its users to
build up libraries of scripts. Users are able to include their own personal
scripts or site-wide scripts.
</t>
</abstract>
</front>
<middle>
<note title='Change History (to be removed prior to publication as an RFC)'>
<t>Changes from ietf-06 to ietf-07:
<list style='letters'>
<t>Nits from Stephan Bosch.</t>
</list>
</t>
<t>Changes from ietf-05 to ietf-06:
<list style='letters'>
<t>Nits from Barry Leiba.</t>
</list>
</t>
<t>Changes from ietf-04 to ietf-05:
<list style='letters'>
<t>Integrate review from Barry Leiba.</t>
</list></t>
<t>Changes from ietf-03 to ietf-04:
<list style='letters'>
<t>No changes.</t>
</list></t>
<t>Changes from ietf-02 to ietf-03:
<list style='letters'>
<t>Setting a variable then calling global on it is an error (something like 'use strict').</t>
<t>Specify that the 'global' keyword is only available when 'variables' has also been required.</t>
<t>Uploading a script that includes a nonexistent script is not an error at upload time.</t>
</list></t>
<t>Changes from ietf-01 to ietf-02:
<list style='letters'>
<t>Require that script names must be constant strings, not subject to variable expansion.</t>
<t>Try the phrase immediate script instead of current script.</t>
<t>Clarify that "global 'varname'" and "global.varname" refer to the same variable.</t>
<t>Drop the requirement the global keywords come after require and before anything else.</t>
</list></t>
<t>Changes from ietf-00 to ietf-01:
<list style='letters'>
<t>Replaced import/export with global.</t>
<t>Added :once modifier to include.</t>
<t>Added global namespace to see if it holds water.</t>
</list></t>
<t>Changes from daboo-06 to ietf-00:
<list style='letters'>
<t>None</t>
</list></t>
<t>Changes from -05 to -06:
<list style='letters'>
<t>Aaron Stone joins as author.</t>
<t>Removed | characters from the script examples.</t>
<t>Updated draft references to published RFCs.</t>
</list></t>
<t>Changes from -04 to -05:
<list style='letters'>
<t>Fixed examples.</t>
<t>Relaxed requirement that imported/exported variables be set before being used.</t>
</list></t>
<t>Changes from -03 to -04:
<list style='letters'>
<t>Fixed missing 2119 definitions.</t>
<t>Defined interaction with variables through use of import and export commands.</t>
</list></t>
<t>Changes from -02 to -03:
<list style='letters'>
<t>Refreshing expired draft (updated for nits).</t>
<t>Syntax -> Usage.</t>
<t>Updated to 3028bis reference.</t>
</list></t>
<t>Changes from -01 to -02:
<list style='letters'>
<t>Minor formatting changes only - refreshing expired draft.</t>
</list></t>
<t>Changes from -00 to -01:
<list style='letters'>
<t>Added IPR boiler plate.</t>
<t>Re-ordered sections at start to conform to RFC style.</t>
<t>Moved recursion comment into General Considerations section.</t>
<t>Switched to using optional parameter to indicate personal vs global.</t>
<t>Explicitly state that an error occurs when a missing script is included.</t>
</list></t>
</note>
<section title='Introduction and Overview'>
<t>
It's convenient to be able to break <xref target='RFC5228'>SIEVE</xref>
scripts down into smaller components which can be reused in a variety
of different circumstances. For example, users may want to have a
default script and a special 'vacation' script, the latter being
activated when the user goes on vacation. In that case the default
actions should continue to be run, but a vacation command should be
executed first. One option is to edit the default script to add or
remove the vacation command as needed. Another is to have a vacation
script that simply has a vacation command and then includes the default
script.
</t>
</section>
<section title='Conventions Used in This Document'>
<t>
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 <xref target='RFC2119'/>.
</t>
<t>
Conventions for notations are as in <xref target='RFC5228'>SIEVE</xref>
Section 1.1.
</t>
<t>
The following key phrases are used to describe scripts and script execution:
<list style="hanging">
<t hangText="script"><vspace />
a valid Sieve script.
</t>
<t hangText="script execution"><vspace />
an instance of a Sieve interpreter invoked for a
given message delivery, starting with the user's active script and
continuing through any included scripts until the message is
delivered.
</t>
<t hangText="immediate script"><vspace />
the individual Sieve script file being executed.
</t>
<t hangText="including script"><vspace />
the individual Sieve script file that had an
include statement which included the immediate script.
</t>
</list>
</t>
</section>
<section title='Include Extension'>
<section title='General Considerations'>
<t>
Sieve implementations that implement the "include", "return", and
"global" commands described below have an identifier of "include" for
use with the capability mechanism. If any of the "include", "return",
or "global" commands are used in a script, the "include" capability
MUST be listed in the "require" statement in that script.
</t>
<t>
Sieve implementations need to track the use of actions in included
scripts so that implicit "keep" behavior can be properly determined
based on whether any actions have executed in any script.
</t>
<t>
Sieve implementations are allowed to limit the total number of
nested included scripts, but MUST provide for a total of at least
three levels of nested scripts including the top-level script. An
error MUST be generated either when the script is uploaded to the
Sieve repository, or when the script is executed, if any nesting
limit is exceeded. If such an error is detected whilst processing a
Sieve script, an implicit "keep" action MUST be executed to prevent
loss of any messages.
</t>
<t>
Sieve implementations MUST ensure that recursive includes are not
possible. For example, if script "A" includes script "B", and script "B"
includes script "A" an error MUST be generated either when the script
is uploaded to the Sieve repository, or when the script is executed.
If such an error is detected whilst processing a Sieve script, an
implicit "keep" action MUST be executed to prevent loss of any
messages.
</t>
<t>
Sieve implementations MUST generate an error at execution time if an
included script does not exist. Implementations MUST NOT generate
errors for scripts missing at upload time, as this would force
an upload ordering requirement upon script authors / generators.
</t>
<t>
If the Sieve "variables" extension <xref target='RFC5229'/> is
present, an issue arises with the "scope" of variables defined in
scripts that may include each other. For example, if a script defines
the variable "${status}" with one particular meaning or usage, and
another defines "${status}" with a different meaning, then if one
script includes the other there is an issue as to which "${status}"
is being referenced. To solve this problem, Sieve implementations
MUST follow the scoping rules defined in <xref target='variables'/>
and support the "global" command defined there.
</t>
</section>
<section title='Control Structure include'>
<figure>
<artwork><![CDATA[
Usage: include [LOCATION] [ONCE] <value: string>
LOCATION = ":personal" / ":global"
ONCE = ":once"
]]></artwork>
</figure>
<t>
The "include" command takes an optional "location" parameter, an
optional ":once" parameter, and a single string argument representing
the name of the script to include for processing at that point. It is
RECOMMENDED that implementations restrict script names according to
<xref target='RFC5804'>MANAGESIEVE</xref> Section 1.7. Implementations MUST NOT
allow variables to be expanded into the names of Sieve scripts; in
other words, the value MUST be a constant string as defined in
<xref target='RFC5229'>VARIABLES</xref>, Section 3.
</t>
<t>
The "location" parameter MUST default to ":personal" if not specified.
The "location" has the following meanings:
</t>
<t>
<list style="hanging">
<t hangText=":personal"><vspace />
Indicates that the named script is stored in the user's own
personal (private) Sieve repository.
</t>
<t hangText=":global"><vspace />
Indicates that the named script is stored in a site-wide Sieve
repository, accessible to all users of the Sieve system.
</t>
</list>
</t>
<t>
The ":once" parameter tells the interpreter only to include the named
script if it has not already been included at any other point during
script execution. If the script has already been included, processing
continues immediately following the include command. Implementations
MUST NOT generate an error if an "include :once" command names a script
whose inclusion would be recursive; in this case, the script MUST
be considered previously included and therefore "include :once" will not
include it again.
</t>
<t>
Note: It is RECOMMENDED that script authors / generators use this
parameter only when including a script that performs general duties
such as declaring global variables and making sanity checks of the
environment.
</t>
<t>
The included script MUST be a valid Sieve script, including having
necessary "require" statements for all optional capabilities used by
the script. The scope of a "require" statement in an included script
is for the immediate script only, not the including script. For example, if
script "A" includes script "B", and script "B" uses the "fileinto"
extension, script "B" must have a "require" statement for "fileinto",
irrespective of whether script "A" has one. In addition, if script
"A" does not have a "require" statement for "fileinto", "fileinto"
cannot be used anywhere in script "A", even after inclusion of script
"B".
</t>
<t>
A "stop" command in an included script MUST stop all script
processing, including the processing of the scripts that include the
immediate one. The "return" command (described below) stops processing
of the immediate script only, and allows the scripts that include it to
continue.
</t>
<t>Examples:</t>
<t>The user has four scripts stored in their personal repository:</t>
<t>"default"</t>
<t><list>
<t>This is the default active script that includes several others.</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["include"];
include :personal "always_allow";
include :global "spam_tests";
include :personal "spam_tests";
include :personal "mailing_lists";
]]></artwork>
</figure>
<t>Personal script "always_allow"</t>
<t><list>
<t>This script special-cases some correspondent email addresses and
makes sure any message containing those addresses are always kept.
</t>
</list></t>
<figure>
<artwork><![CDATA[
if address :is "from" "boss@example.com"
{
keep;
}
elsif address :is "from" "ceo@example.com"
{
keep;
}
]]></artwork>
</figure>
<t>Personal script "spam_tests"</t>
<t><list>
<t>
This script does some user-specific spam tests to catch spam
messages not caught by the site-wide spam tests.
</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["reject"];
if header :contains "Subject" "XXXX"
{
reject "Subject XXXX is unacceptable.";
}
elsif address :is "from" "money@example.com"
{
reject "Mail from this sender is unwelcome.";
}
]]></artwork>
</figure>
<t>Personal script "mailing_lists"</t>
<t><list>
<t>
This script looks for messages from different mailing lists and
files each into a mailbox specific to the mailing list.
</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["fileinto"];
if header :is "List-ID" "sieve.ietf.org"
{
fileinto "lists.sieve";
}
elsif header :is "List-ID" "ietf-imapext.imc.org"
{
fileinto "lists.imapext";
}
]]></artwork>
</figure>
<t>There is one script stored in the global repository:</t>
<t>Site script "spam_tests"</t>
<t><list>
<t>
This script does some site-wide spam tests which any user at the
site can include in their own scripts at a suitable point. The
script content is kept up to date by the site administrator.
</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["reject"];
if anyof (header :contains "Subject" "$$",
header :contains "Subject" "Make money")
{
reject;
}
]]></artwork>
</figure>
<t>
The "include" command may appear anywhere in the script where a
control structure is legal.
</t>
<t>Example:</t>
<figure>
<artwork><![CDATA[
require ["include"];
if anyof (header :contains "Subject" "$$",
header :contains "Subject" "Make money")
{
include "my_reject_script";
}
]]></artwork>
</figure>
</section>
<section title='Control Structure return'>
<figure>
<artwork><![CDATA[
Usage: return
]]></artwork>
</figure>
<t>
The "return" command stops processing of the immediately included
script only and returns processing control to the script which
includes it. If used in the main script (i.e., not in an included
script), it has the same effect as the "stop" command, including the
appropriate "keep" action if no other actions have been executed up
to that point.
</t>
</section>
<section anchor='variables' title='Interaction with Variables'>
<t>
In order to avoid problems of variables in an included script
"overwriting" those from the script that includes it, this
specification requires that all variables defined in a script MUST be
kept "private" to the immediate script by default - that is, they are not
"visible" to other scripts. This ensures that two script authors
cannot inadvertently cause problems by choosing the same name for a
variable.
</t>
<t>
However, sometimes there is a need to make a variable defined in one
script available to others. This specification defines the new
command "global" to declare that a variable is shared among scripts.
Effectively, two namespaces are defined: one local to the immediate
script, and another shared among all scripts. Implementations MUST
allow a non-global variable to have the same name as a global
variable but have no interaction between them.
</t>
<section title='Control Structure global'>
<figure>
<artwork><![CDATA[
Usage: global <value: string-list>
]]></artwork>
</figure>
<t>
The "global" command contains a string list argument that defines
one or more names of variables to be stored in the global variable
space.
</t>
<t>
The "global" command is only available when the script has both
"include" and "variables" in its require line. If the "global"
command appears when only "include" or only "variables" has been
required, an error MUST be generated when the script is uploaded.
</t>
<t>
If a "global" command is given the name of a variable that has
previously been defined in the immediate script with "set", an
error MUST be generated either when the script is uploaded or at
execution time.
</t>
<t>
If a "global" command lists a variable that has not been defined in
the global namespace, the name of the variable is now
marked as global, and any subsequent "set" command will set the
value of the variable in global scope.
</t>
<t>
A variable has global scope in all scripts that have declared it with
the "global" command. If a script uses that variable name without
declaring it global, the name specifies a separate, non-global
variable within that script.
</t>
<t>
Interpretation of a string containing a variable marked as global,
but without any value set, SHALL behave as any other access to an
unknown variable, as specified in <xref target='RFC5229'>VARIABLES</xref>, Section 3
(i.e., evaluates to an empty string).
</t>
<t>Example:</t>
<t>The active script</t>
<t><list>
<t>
The included script may contain repetitive code that is
effectively a subroutine that can be factored out. In this
script, the test which matches last will leave its value in
the test-mailbox variable and the top-level script will
file the message into that mailbox. If no tests matched,
the message will be implicitly kept in the INBOX.
</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["include", "variables", "relational"];
global "test";
global "test-mailbox";
set "test" "$$"
include "spam_checks";
set "test" "Make money"
include "spam_checks";
if string :count "eq" "${test-mailbox}" "1"
{
fileinto "${test-mailbox}";
stop;
}
]]></artwork>
</figure>
<t>Personal script "spam_checks"</t>
<t><list>
<t>
This script is makes a number of tests against the message, falling
through back to the top-level script having set the global test-mailbox
variable with a target folder to file the message into.
</t>
</list></t>
<figure>
<artwork><![CDATA[
require ["include", "variables"];
global ["test", "test-mailbox"];
if header :contains "Subject" "${test}"
{
set "test-mailbox" "spam-${test}";
}
]]></artwork>
</figure>
</section>
<section title='Variables Namespace global'>
<t>
In addition to the "global" command, this document defines the
variables namespace "global", as specified in
<xref target="RFC5229">VARIABLES</xref>, Section 3.
</t>
<t>Example:</t>
<figure>
<artwork><![CDATA[
require ["variables", "include"];
set "global.i_am_on_vacation" "1";
]]></artwork>
</figure>
<t>
Variables declared global and variables accessed via the global
namespace MUST be one and the same. In the following example
script, we see the variable "i_am_on_vacation" used in a "global"
command, and again with the "global." namespace. Consider these as
two syntaxes with identical meaning.
</t>
<t>Example:</t>
<figure>
<artwork><![CDATA[
require ["variables", "include"];
global "i_am_on_vacation";
set "global.i_am_on_vacation" "1";
if string :is "${i_am_on_vacation}" "1"
{
vacation "It's true, I am on vacation."
}
]]></artwork>
</figure>
</section>
</section>
</section>
<section title='Security Considerations'>
<t>
Sieve implementations MUST ensure adequate security for the global
script repository to prevent unauthorized changes to global scripts.
</t>
<t>
Sieve implementations MUST ensure that script names are checked for
validity and proper permissions prior to inclusion, in order to prevent
a malicious user from gaining acess to files accessible to the mail
server software that should not be accessible to the user.
</t>
<t>
Beyond these, the "include" extension does not raise any security
considerations that are not present in the base
<xref target='RFC5228'>SIEVE</xref> document and the
<xref target='RFC5229'>VARIABLES</xref> extension.
</t>
</section>
<section anchor="iana" title="IANA Considerations">
<t>
The following template specifies the IANA registration of the Sieve
extension specified in this document:
</t>
<section anchor="iana-include" title=""include" Extension Registration">
<figure>
<artwork><![CDATA[
Capability name: include
Description: adds the "include" command to execute other Sieve
scripts, and the "global" command and "global"
variables namespace to access variables shared
among included scripts.
RFC number: this RFC
Contact address: the Sieve discussion list <sieve@ietf.org>
]]></artwork>
</figure>
</section>
</section>
</middle>
<back>
<references title="Normative References">
&rfc2119;
&rfc5228;
&rfc5229;
</references>
<references title="Informative References">
&rfc5804;
</references>
<section title="Acknowledgments">
<t>
Thanks to Ken Murchison, Rob Siemborski, Alexey Melnikov, Marc Mutz,
Kjetil Torgrim Homme, Stephan Bosch, Arnt Gulbrandsen, Barry Leiba, and
Jeffrey Hutzelman for comments and corrections.
</t>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 16:43:49 |