Network Working Group Tim Martin
INTERNET-DRAFT BeThereBeSquare Inc.
Intended status: Standards Track Alexey Melnikov
Expires: February 2008 Isode Limited
August 14, 2007
A Protocol for Remotely Managing Sieve Scripts
<draft-martin-managesieve-08.txt>
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Sieve scripts allow users to filter incoming email. Message stores
are commonly sealed servers so users cannot log into them, yet users
must be able to update their scripts on them. This document
describes a protocol "sieve" for securely managing Sieve scripts on
a remote server. This protocol allows a user to have multiple
scripts, and also alerts a user to syntactically flawed scripts.
Table of Contents
Status of this Memo . . . . . . . . . . . . . . . . . . . . . . . . 1
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Conventions Used in the Document . . . . . . . . . . . . . . 4
1.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4. Response Codes . . . . . . . . . . . . . . . . . . . . . . . 5
1.5. Active Script . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6. Quotas . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.7. Script Names . . . . . . . . . . . . . . . . . . . . . . . . 7
1.8. Capabilities . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Commands . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1. AUTHENTICATE Command . . . . . . . . . . . . . . . . . . . . 8
2.2. STARTTLS Command . . . . . . . . . . . . . . . . . . . . . . 10
2.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . . . . . 10
2.4. CAPABILITY Command . . . . . . . . . . . . . . . . . . . . . 11
2.5. HAVESPACE Command . . . . . . . . . . . . . . . . . . . . . . 11
2.6. PUTSCRIPT Command . . . . . . . . . . . . . . . . . . . . . . 11
2.7. LISTSCRIPTS Command . . . . . . . . . . . . . . . . . . . . . 13
2.8. SETACTIVE Command . . . . . . . . . . . . . . . . . . . . . . 13
2.9. GETSCRIPT Command . . . . . . . . . . . . . . . . . . . . . . 13
2.10. DELETESCRIPT Command . . . . . . . . . . . . . . . . . . . . 14
3. Sieve URL Scheme . . . . . . . . . . . . . . . . . . . . . . 14
4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. References . . . . . . . . . . . . . . . . . . . . . . . . .
7.1. Normative References . . . . . . . . . . . . . . . . . . . .
7.2. Informative References . . . . . . . . . . . . . . . . . . .
8. Author's Address . . . . . . . . . . . . . . . . . . . . . .
1. Introduction
1.1. Changes
[[Note to RFC editor: please delete this section before
publication]]
Changes since 07
-Fixed examples to match 3028bis - capability names are case
sensitive, so examples should show "fileinto" instead of
"FILEINTO", etc.
-Minor editorial changes
Changes since 06
-Clarified meaning of the QUOTA response code
-Clarified which characters are not allowed in script names
and the maximum script name length
-Clarified that the empty list of SASL mechanisms is allowed
-Clarified that PUTSCRIPT must not store data after anonymous
authentication
-Move text about NOTIFY capability into this document
-Additional examples
-Updated ABNF, References, Contact information
Changes since 05
-More ABNF fixes
-Added IANA considerations
-Added/fixed text about AUTHENTICATE.
-Updated the text om Sieve URLs.
-Updated and added new examples.
Changes since 04
-Updated boilerplate and some references. Added Alexey as co-editor.
-Minor ABNF fixes
-Cleaned up terminology (for example, made more consistent with
SASL)
-Added more examples, fixed some existing examples
-Clarified that STARTTLS command is optional
-Clarified that disabling an active script when there is no script
active is not an error.
Changes since 03
-Add referals and Sieve URLs
-Lots of spelling/grammer fixes
-Don't give capabilities after successful STARTTLS. This is because
it isn't consistant with AUTHENTICATE. There is language specifying
that a client should re-issue a CAPABILITY command after
AUTHENTICATE/STARTTLS.
-Putting a script of length 0 doesn't remove the script. If this
functionality is desired, the DELETESCRIPT command should be used.
Changes since 02
-add BYE response
-typo on line 588
-allow ANONYMOUS access for sieve script verification
-updated SIEVE spec reference
Changes since 01
-changed contact info
Changes since 00
-added response codes (from ACAP)
-removed special-ok response from authenticate command (response
codes obsolete it)
-changed service name to "sieve"
-ABNF fixes
-Alexey's wording changes
-Eliminated lame PLAIN paragraph
Changes since PRE
-dropped synchronized literals. added HAVESPACE command
-changed capability response syntax. added CAPABILITY command
-allowed pipelining
- "sieve" -> "Sieve". Other minor fixes
-made script names more flexible
-added starttls support
1.2. Conventions Used in the 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 [KEYWORDS].
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively. Line breaks that do not start a new "C:" or
"S:" exist for editorial reasons.
1.3. Syntax
This a line oriented protocol much like [IMAP4rev1] or [ACAP]. There
are three types: ATOMS, numbers and strings. Strings may be quoted
or literal. See [ACAP] for detailed descriptions of these types.
<<Clarify that the CRLF after the literal size is not "end of the
line">>
Each command consists of an atom followed by zero or more strings
and numbers terminated by a newline.
All client queries are replied to with either an OK, NO, or BYE
response. Each response may be followed by a response code (see
response codes section) and by a string consisting of human readable
text in the local language. The contents of the string SHOULD be
shown to the user and implementations MUST NOT attempt to parse the
message for meaning.
The BYE response may be used if the server wishes to close the
connection. A server may wish to do this because the client was idle
for too long or there were too many failed authentication attempts.
This response can be issued at any time and should be immediately
followed by a server hang-up of the connection. If a server has a
inactivity timeout resulting in client autologout it MUST be no less
than 30 minutes.
<<IANA registration is pending. Current implementations generally
use port number 2000.>>
1.4. Response Codes
An OK, NO, or BYE response from the server MAY contain a response
code to describe the event in a more detailed machine parsable
fashion. A response code consists of data inside parentheses in the
form of an atom, possibly followed by a space and arguments.
Response codes are defined when there is a specific action that a
client can take based upon the additional information. In order to
support future extension, the response code is represented as a
slash-separated hierarchy with each level of hierarchy representing
increasing detail about the error. Clients MUST tolerate additional
hierarchical response code detail which they don't understand.
The currently defined response codes are:
AUTH-TOO-WEAK
This response code is returned in the NO response from an
AUTHENTICATE command. It indicates that site security policy forbids
the use of the requested mechanism for the specified authentication
identity.
ENCRYPT-NEEDED
This response code is returned in the NO response from an
AUTHENTICATE command. It indicates that site security policy
requires the use of a strong encryption mechanism for the specified
authentication identity and mechanism.
QUOTA
If this response code is returned in the NO/BYE response, it means
that the command would have placed the user above the site-defined
quota constraints. If this response code is returned in the OK
response, it can mean that the user is near its quota or that the
user exceeded its quota, but the server supports soft quotas.
REFERRAL
This response code may be returned with a BYE result from any
command, and includes a mandatory parameter that indicates what
server to access to manage this user's sieve scripts. The server
will be specified by a Sieve URL (see "Sieve URL Scheme" section).
The scriptname portion of the URL MUST NOT be specified. The client
should authenticate to the specified server and use it for all
further commands in the current session.
SASL
This response code can occur in the OK response to a successful
AUTHENTICATE command and includes the optional final server response
data from the server as specified by [SASL].
TRANSITION-NEEDED
This response code occurs in a NO response of an AUTHENTICATE
command. It indicates that the user name is valid, but the entry in
the authentication database needs to be updated in order to permit
authentication with the specified mechanism. This is typically done
by establishing a secure channel using TLS, followed by
authenticating once using the [PLAIN] authentication mechanism.
The selected mechanism SHOULD then work for authentications in
subsequent sessions.
This condition can happen if a user has an entry in a system
authentication database such as Unix /etc/passwd, but does not have
credentials suitable for use by the specified mechanism.
TRYLATER
A command failed due to a temporary server failure. The client MAY
continue using local information and try the command later. This
response code only make sense when returned in a NO/BYE response.
Client implementations MUST tolerate response codes that they do not
recognize.
1.5. Active Script
A user may have multiple Sieve scripts on the server, yet only one
script may be used for filtering of incoming messages. This is the
active script. Users may have zero or one active scripts and MUST
use the SETACTIVE command described below for changing the active
script or disabling Sieve processing. For example, a user may have
an everyday script they normally use and a special script they use
when they go on vacation. Users can change which script is being
used without having to download and upload a script stored somewhere
else.
1.6. Quotas
Servers SHOULD impose quotas to prevent malicious users from
overflowing available storage. If a command would place a user over
a quota setting, servers that impose such quotas MUST reply with a
NO response. Client implementations MUST be able to handle commands
failing because of quota restrictions.
1.7. Script Names
Sieve script names may contain any valid UTF-8 characters, except
for NUL, CR or LF. Names MUST be at least one octet long. Zero
octets script name has special meaning (see SETACTIVE command
section). Servers MUST allow names of up to 128 Unicode characters
in length, and MAY allow longer names.
1.8. Capabilities
Server capabilities are sent by the server upon a client connection.
Clients may request the capabilities at a later time by issuing the
CAPABILITY command described later. The capabilities consist of a
series of lines each with one or two strings. The first string is
the name of the capability, which is case-insensitive. The second
optional string is the value associated with that capability.
Order of capabilities is arbitrary, but each capability name can
appear at most once.
The following capabilities are defined in this document:
IMPLEMENTATION - Name of implementation and version
SASL - List of SASL mechanisms supported by the server, each
separated by a space. This list can be empty if and only if
STARTTLS is also advertised. This means that the client must
negotiate TLS encryption with STARTTLS first, at which point
the SASL capability will list a non empty list of SASL mechanisms.
<<But STARTTLS is optional!>>
SIEVE - List of space separated Sieve extensions (as listed
in Sieve "require" action [SIEVE]) supported by the Sieve engine
STARTTLS - If TLS [TLS] is supported by this implementation
NOTIFY - A space separated list of URI schema parts for supported
notification methods. This capability MUST be specified if the
Sieve implementation supports the "enotify" extension
[NOTIFY].
A server implementation MUST return SIEVE and IMPLEMENTATION
capabilities.
A client implementation MUST ignore any listed capabilities
that it does not understand.
Example:
S: "IMPlemENTATION" "Example1 ManageSieved v001"
S: "SASl" "DIGEST-MD5 GSSAPI"
S: "SIeVE" "fileinto vacation"
S: "StaRTTLS"
S: "NOTIFY" "xmpp mailto"
S: OK
<<Add RENAMESCRIPT>>
2. Commands
The following commands are valid. Prior to successful authentication
only the AUTHENTICATE, CAPABILITY, STARTTLS, and LOGOUT commands are
valid. Servers MUST reject all other commands with a NO response.
Clients may pipeline commands (send more than one command at a time
without waiting for completion of the first command ). However, a
group of commands sent together MUST NOT have an AUTHENTICATE,
a STARTTLS or a HAVESPACE command anywhere but the last command in
the list.
2.1. AUTHENTICATE Command
Arguments:
String - mechanism
String - initial data (optional)
The AUTHENTICATE command indicates a SASL [SASL] authentication
mechanism to the server. If the server supports the requested
authentication mechanism, it performs an authentication protocol
exchange to identify and authenticate the user. Optionally, it also
negotiates a security layer for subsequent protocol interactions.
If the requested authentication mechanism is not supported, the
server rejects the AUTHENTICATE command by sending the NO response.
The authentication protocol exchange consists of a series of server
challenges and client responses that are specific to the selected
authentication mechanism. A server challenge consists of a string
(quoted or literal) followed by a CRLF. The contents of the string
is a base-64 encoding [BASE64] of the SASL data. A client response
consists of a string (quoted or literal) with the base-64 encoding
of the SASL data followed by a CRLF. If the client wishes to cancel
the authentication exchange, it issues a string containing a single
"*". If the server receives such a response, it MUST reject the
AUTHENTICATE command by sending an NO reply.
Note that an empty challenge/response is sent as an empty string.
If the mechanism dictates that the final response is sent by the
server this data MAY be placed within the data portion of the SASL
response code to save a round trip.
The optional initial-response argument to the AUTHENTICATE command
is used to save a round trip when using authentication mechanisms
that are defined to send no data in the initial challenge. When the
initial-response argument is used with such a mechanism, the initial
empty challenge is not sent to the client and the server uses the
data in the initial-response argument as if it were sent in response
to the empty challenge. If the initial-response argument to the
AUTHENTICATE command is used with a mechanism that sends data in the
initial challenge, the server rejects the AUTHENTICATE command by
sending the NO response.
The service name specified by this protocol's profile of SASL is
"sieve".
Reauthentication is not supported by ManageSieve protocol's profile
of SASL. I.e. after a successfully completed AUTHENTICATE command,
no more AUTHENTICATE commands may be issued in the same session.
After a successful AUTHENTICATE command completes, a server MUST
reject any further AUTHENTICATE commands with a NO reply.
If a security layer is negotiated through the SASL authentication
exchange, it takes effect immediately following the CRLF that
concludes the authentication exchange for the client, and the CRLF
of the OK response for the server.
When a security layer takes effect, the ManageSieve protocol is
reset to the initial state (the state in ManageSieve after a client
has connected to the server). The server MUST discard any
knowledge obtained from the client which was not obtained from
the SASL (or TLS) negotiation itself.
Likewise, the client MUST discard any knowledge obtained from
the server, such as the list of ManageSieve extensions, which
was not obtained from the SASL (or TLS) negotiation itself.
(Note that a client MAY compare the advertised SASL mechanisms
before and after authentication in order to detect an active
down-negotiation attack. See below.)
Once a SASL security layer is established, the server MUST re-issue
the capability results, followed by an OK response. This is
necessary to protect against man-in-the-middle attacks which alter
the capabilities list prior to SASL negotiation.
The capability results MUST include all SASL mechanisms. This is
done in order to allow client to detect active down-negotiation
attack.
When both [TLS] and SASL security layers are in effect, the
TLS encoding MUST be applied (when sending data) after the SASL
encoding, regardless of the order in which the layers were
negotiated.
Server implementations SHOULD support SASL proxy authentication so
that an administrator can administer a user's scripts. Proxy
authentication is when a user authenticates as herself/himself but
requests the server to act (authorize) as another user.
<<The authorization identity generated by this [SASL] exchange
is a simple username, and both client and server MUST use the
[SASLprep] profile of the [StringPrep] algorithm to prepare
these names for transmission or comparison. If preparation of
the authorization identity fails or results in an empty string
(unless it was transmitted as the empty string), the server
MUST fail the authentication.>>
If an AUTHENTICATE command fails with a NO response, the client may
try another authentication mechanism by issuing another AUTHENTICATE
command. In other words, the client may request authentication
types in decreasing order of preference.
Note that a failed NO response to the AUTHENTICATE command may
contain one of the following response codes: AUTH-TOO-WEAK,
ENCRYPT-NEEDED or TRANSITION-NEEDED. See section 1.4 for detailed
description of the relevant conditions.
To ensure interoperability, client and server implementations
of this extension MUST implement the [DIGEST-MD5] SASL
mechanism. <<What is the IESG policy on this?>>
Implementations MAY advertise the ANONYMOUS SASL mechanism
[SASL-ANON]. This indicates that the server supports ANONYMOUS SIEVE
script syntax verification. Only the CAPABILITY, PUTSCRIPT and
LOGOUT commands are available to the anonymous user. All other
commands MUST give NO responses. Furthermore the PUTSCRIPT command
MUST NOT persistently store any data. In this mode a positive
response to the PUTSCRIPT command indicates that the given script
does not have any syntax errors.
Examples (Note that long lines are folded for readability and are
not part of protocol exchange):
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" "DIGEST-MD5 GSSAPI"
S: "SIEVE" "fileinto vacation"
S: "STARTTLS"
S: OK
C: Authenticate "DIGEST-MD5"
S: "cmVhbG09ImVsd29vZC5pbm5vc29mdC5jb20iLG5vbmNlPSJPQTZNRzl0
RVFHbTJoaCIscW9wPSJhdXRoIixhbGdvcml0aG09bWQ1LXNlc3MsY2hh
cnNldD11dGYtOA=="
C: "Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
QuaW5ub3NvZnQuY29tIixub25jZT0iT0E2TUc5dEVRR20yaGgiLG5jPTAw
MDAwMDAxLGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLGRpZ2VzdC11cmk9Im
ltYXAvZWx3b29kLmlubm9zb2Z0LmNvbSIscmVzcG9uc2U9ZDM4OGRhZDkw
ZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcscW9wPWF1dGg="
S: OK (SASL "cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZ
mZmZA==")
A slightly different variant of the same authentication exchange:
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" "DIGEST-MD5 GSSAPI"
S: "SIEVE" "fileinto vacation"
S: "STARTTLS"
S: OK
C: Authenticate "DIGEST-MD5"
S: {128+}
S: cmVhbG09ImVsd29vZC5pbm5vc29mdC5jb20iLG5vbmNlPSJPQTZNRzl0
RVFHbTJoaCIscW9wPSJhdXRoIixhbGdvcml0aG09bWQ1LXNlc3MsY2hh
cnNldD11dGYtOA==
C: {276+}
C: Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
QuaW5ub3NvZnQuY29tIixub25jZT0iT0E2TUc5dEVRR20yaGgiLG5jPTAw
MDAwMDAxLGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLGRpZ2VzdC11cmk9Im
ltYXAvZWx3b29kLmlubm9zb2Z0LmNvbSIscmVzcG9uc2U9ZDM4OGRhZDkw
ZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcscW9wPWF1dGg="
S: {56+}
S: cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA==
C: ""
S: OK
Another example demostrating use of SASL PLAIN mechanism under TLS.
This example also demonstrate use of SASL "initial response"
(the second parameter to the Authenticate command):
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" ""
S: "SIEVE" "fileinto vacation"
S: "STARTTLS"
S: OK
C: STARTTLS
S: OK
<TLS negotiation, further commands are under TLS layer>
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" "PLAIN"
S: "SIEVE" "fileinto vacation"
S: OK
C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xu"
S: NO
C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xz"
S: NO
C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xy"
S: BYE "Too many failed authentication attempts"
<Server closes connection>
The following example demonstrate use of SASL "initial response".
It also demonstrates that an empty response can be sent as a
literal:
C: AUTHENTICATE "GSSAPI" {1488+}
C: YIIE[...1480 octets here ...]dA==
S: {208+}
S: YIGZBgkqhkiG9xIBAgICAG+BiTCBhqADAgEFoQMCAQ+iejB4oAMCARKic
[...114 octets here ...]
/yzpAy9p+Y0LanLskOTvMc0MnjgAa4YEr3eJ6
C: {0+}
C:
S: {44+}
S: BQQF/wAMAAwAAAAAYRGFAo6W0vIHti8i1UXODgEAEAA=
C: {44+}
C: BQQE/wAMAAwAAAAAIsT1iv9UkZApw471iXt6cwEAAAE=
S: OK
2.2. STARTTLS Command
Support for STARTTLS command in servers is optional. Its
availability is advertised with "STARTTLS" capability as described
in section 1.8.
The STARTTLS command requests commencement of a TLS negotiation.
The negotiation begins immediately after the CRLF in the OK
response. After a client issues a STARTTLS command, it MUST NOT
issue further commands until a server response is seen and the TLS
negotiation is complete.
The STARTTLS command is only valid in non-authenticated state. The
server remains in non-authenticated state, even if client
credentials are supplied during the TLS negotiation. The SASL [SASL]
EXTERNAL mechanism MAY be used to authenticate once TLS client
credentials are successfully exchanged, but servers supporting the
STARTTLS command are not required to support the EXTERNAL mechanism.
After the TLS layer is established, the server MUST re-issue the
capability results, followed by an OK response. This is necessary to
protect against man-in-the-middle attacks which alter the
capabilities list prior to STARTTLS. This capability result MUST NOT
include the STARTTLS capability.
The client MUST discard cached capability information and replace it
with the new information. The server MAY advertise different
capabilities after STARTTLS.
Example:
C: StartTls
S: oK
<TLS negotiation, further commands are under TLS layer>
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" "PLAIN DIGEST-MD5 GSSAPI"
S: "SIEVE" "fileinto vacation"
S: ok
2.3. LOGOUT Command
The client sends the LOGOUT command when it is finished with a
connection and wishes to terminate it. The server MUST reply with an
OK response and terminate the connection. The server MUST ignore
commands issued by the client after the LOGOUT command.
Example:
C: Logout
S: Ok
<connection terminated>
2.4. CAPABILITY Command
The CAPABILITY command requests the server capabilities as described
earlier in this document. While the capabilities are sent upon
connection, they may change during authentication. The client SHOULD
issue a CAPABILITY command after successful authentication or after
negotiating a security layer using STARTTLS.
Example:
C: CAPABILITY
S: "IMPLEMENTATION" "Example1 ManageSieved v001"
S: "SASL" "PLAIN KERBEROS_V4 GSSAPI"
S: "SIEVE" "fileinto vacation"
S: "STARTTLS"
S: OK
2.5. HAVESPACE Command
Arguments:
String - name
Number - size
The HAVESPACE command is used to query the server for available
space. Clients specify the name they wish to save the script as and
its size in octets. Servers respond with an NO if storing a script
with that name and size would fail or OK otherwise. Clients SHOULD
issue this command before attempting to place a script on the
server.
Example:
C: HAVESPACE "myscript" 999999
S: NO (QUOTA) "Quota exceeded"
C: HAVESPACE "foobar" 435
S: OK
2.6. PUTSCRIPT Command
Arguments:
String - Script name
String - Script content
The PUTSCRIPT command is used by the client to submit a Sieve script
to the server.
If the script already exists, upon success the old script will be
overwritten. The old script MUST NOT be overwritten if PUTSCRIPT
fails in any way. A script of zero length SHOULD be disallowed.
This command places the script on the server. It does not affect
whether the script is processed on incoming mail, unless it replaces
the script which is already active. The SETACTIVE
command is used to mark a script as active.
When submitting large scripts clients SHOULD use the HAVESPACE
command beforehand to query if the server is willing to accept a
script of that size.
The server MUST check the submitted script for syntactic validity.
If the script fails this test the server MUST reply with a NO
response. Any script that fails the validity test MUST NOT be stored
on the server. The message given with a NO response MUST be human
readable and SHOULD contain a specific error message giving the line
number of the first error. Implementors should strive to produce
helpful error messages similar to those given by programming
language compilers. Client implementations should note that this may
be a multiline literal string with more than one error message
separated by newlines.
Example:
C: Putscript "foo" {31+}
C: #comment
C: InvalidSieveCommand
C:
S: NO "line 2: Syntax error"
C: Putscript "mysievescript" {110+}
C: require ["fileinto"];
C:
C: if envelope :contains "to" "tmartin+sent" {
C: fileinto "INBOX.sent";
C: }
S: OK
2.7. LISTSCRIPTS Command
This command lists the scripts the user has on the server. Upon
success a list of CRLF separated script names (each represented
as a quoted or literal string) is returned followed by an OK
response. If there exists an active script the atom ACTIVE is
appended to the corresponding script name. The atom ACTIVE
MUST NOT appear on more than one response line.
Example:
C: Listscripts
S: "summer_script"
S: "vacation_script"
S: {13+}
S: clever"script
S: "main_script" ACTIVE
S: OK
C: listscripts
S: "summer_script"
S: "main_script" active
S: OK
2.8. SETACTIVE Command
Arguments:
String - script name
This command sets a script active. If the script name is the empty
string (i.e. "") then any active script is disabled. Disabling an
active script when there is no script active is not an error and
MUST result in OK reply.
If the script does not exist on the server then the server MUST
reply with a NO response.
Examples:
C: Setactive "vacationscript"
S: Ok
C: Setactive ""
S: Ok
C: Setactive "baz"
S: No "There is no script by that name"
C: Setactive "baz"
S: No {31+}
S: There is no script by that name
2.9. GETSCRIPT Command
Arguments:
String - Script name
This command gets the contents of the specified script. If the
script does not exist the server MUST reply with a NO response. Upon
success a string with the contents of the script is returned
followed by a OK response.
Example:
C: Getscript "myscript"
S: {54+}
S: #this is my wonderful script
S: reject "I reject all";
S:
S: OK
2.10. DELETESCRIPT Command
Parameters:
sieve-name - Script name
This command is used to delete a user's Sieve script. Servers MUST
reply with a NO response if the script does not exist. The server
MUST NOT allow the client to delete an active script, so the server
MUST reply with a NO response if attempted. If a client wishes to
delete an active script it should use the SETACTIVE command to
disable the script first.
Example:
C: Deletescript "foo"
S: Ok
C: Deletescript "baz"
S: No "You may not delete an active script"
3. Sieve URL Scheme
URI scheme name: sieve
Status: permanent
URI scheme syntax:
Described using ABNF [ABNF] and ABNF entities from [URI-GEN].
sieveurl = sieveurl-server / sieveurl-script
sieveurl-server = "sieve://" authority
sieveurl-script = "sieve://" [ authority ] "/" scriptname
scriptname = *pchar
URI scheme semantics:
A Sieve URL identifies a Sieve server or a Sieve
script on a Sieve server. <<The latter form is associated with
application/sieve MIME type.>>
<<There is no MIME type associated with this URI.>>
The server form is used in the REFERRAL response code in order
to designate another server where the client should perform
its operations.
The script form allows to retrieve (GETSCRIPT), update
(PUTSCRIPT), delete (DELETESCRIPT) or activate (SETACTIVE)
the named script, however the most typical action would be to
retrieve the script. If the script name is empty, the URI
requests that the client lists available scripts using
the LISTSCRIPTS command.
Encoding considerations: The script name, if present,
is in UTF-8. Non-US-ASCII UTF-8 octets MUST be percent-encoded as
described in [URI-GEN].
The user name (in the "authority" part), if present,
is in UTF-8. Non-US-ASCII UTF-8 octets MUST be percent-encoded as
described in [URI-GEN].
Applications/protocols that use this URI scheme name:
ManageSieve [RFC XXXX] clients and servers.
Clients that can store user preferences in protocols such as
LDAP or ACAP. <<Add ref>>
Interoperability considerations: None.
Security considerations: <<None>>.
Contact: Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
References: This document and <<RFC 3028>> [SIEVE].
4. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) notation as specified in [ABNF]. This uses the ABNF core
rules as specified in Appendix A of the ABNF specification [ABNF].
Except as noted otherwise, all alphabetic characters are case-
insensitive. The use of upper or lower case characters to define
token strings is for editorial clarity only. Implementations MUST
accept these strings in a case-insensitive fashion.
SAFE-CHAR = %x01-09 / %x0B-0C / %x0E-21 / %x23-5B /
%x5D-7F
;; any TEXT-CHAR except QUOTED-SPECIALS
QUOTED-CHAR = SAFE-UTF8-CHAR / DQUOTE QUOTED-SPECIALS
QUOTED-SPECIALS = DQUOTE / "\"
SAFE-UTF8-CHAR = SAFE-CHAR / UTF8-2 / UTF8-3 / UTF8-4 /
UTF8-5 / UTF8-6
UTF8-1 = %x80-BF
UTF8-2 = %xC0-DF UTF8-1
UTF8-3 = %xE0-EF 2UTF8-1
UTF8-4 = %xF0-F7 3UTF8-1
UTF8-5 = %xF8-FB 4UTF8-1
UTF8-6 = %xFC-FD 5UTF8-1
auth-type = DQUOTE auth-type-name DQUOTE
auth-type-name = iana-token
;; as defined in SASL [SASL]
command = command-authenticate / command-logout /
command-getscript / command-setactive /
command-listscripts / command-deletescript /
command-putscript / command-capability /
command-havespace / command-starttls
command-authenticate = "AUTHENTICATE" SP auth-type [SP string]
*(CRLF string) CRLF
command-capability = "CAPABILITY" CRLF
command-deletescript = "DELETESCRIPT" SP sieve-name CRLF
command-getscript = "GETSCRIPT" SP sieve-name CRLF
command-havespace = "HAVESPACE" SP sieve-name SP number CRLF
command-listscripts = "LISTSCRIPTS" CRLF
command-logout = "LOGOUT" CRLF
command-putscript = "PUTSCRIPT" SP sieve-name SP string CRLF
command-setactive = "SETACTIVE" SP sieve-name CRLF
command-starttls = "STARTTLS" CRLF
literal = "{" number "+}" CRLF *OCTET
;; The number represents the number of
;; octets.
<<Need to make "+" only allowed from clients to server, to match
IMAP LITERAL+). Also need to also update the examples to match.>>
number = 1*DIGIT
;; A 32-bit unsigned number.
;; (0 <= n < 4,294,967,296)
quoted = DQUOTE *1024QUOTED-CHAR DQUOTE
;; limited to 1024 octets between the <">s
resp-code = "AUTH-TOO-WEAK" / "ENCRYPT-NEEDED" /
"QUOTA" / resp-code-sasl /
resp-code-referral /
"TRANSITION-NEEDED" / "TRYLATER" /
resp-code-ext
resp-code-referral = "REFERRAL" SP sieveurl
resp-code-sasl = "SASL" SP string
resp-code-ext = iana-token [SP extension-data]
;; unknown response codes MUST be tolerated
;; by the client. <<"iana-token" and
;; "extension-data" are defined in ACAP>>
response = response-authenticate /
response-logout /
response-getscript /
response-setactive /
response-listscripts /
response-deletescript /
response-putscript /
response-capability /
response-havespace /
response-starttls
response-authenticate = *(string CRLF) (response-oknobye)
response-capability = *(single-capability) response-oknobye
single-capability = capability-name [SP string] CRLF
capability-name = string
<<Note that literals are allowed!>>
initial-capabilities = DQUOTE "IMPLEMENTATION" DQUOTE SP string /
DQUOTE "SASL" DQUOTE SP sasl-mechs /
DQUOTE "SIEVE" DQUOTE SP sieve-extensions /
DQUOTE "STARTTLS" DQUOTE
;; Each capability conforms to
;; the syntax for single-capability.
;; Also note that the capability name
;; can be returned as either literal
;; or quoted, even though only "quoted"
;; string is shown above.
sasl-mechs = string
; space separated list of SASL mechanisms,
; can be empty
sieve-extensions = string
; space separated list of supported SIEVE extensions,
; can be empty
response-deletescript = response-oknobye
response-getscript = [string CRLF] response-oknobye
<<Need to rewrite ABNF to make it clear that
script content is required with OK response
and must not be sent with the NO (and
possibly BYE) response.>>
response-havespace = response-oknobye
response-listscripts = *(sieve-name [SP "ACTIVE"] CRLF)
response-oknobye
;; ACTIVE may only occur with one sieve-name
response-logout = response-oknobye
response-oknobye = ("OK" / "NO" / "BYE") [SP "(" resp-code ")"]
[SP string] CRLF
response-putscript = response-oknobye
response-setactive = response-oknobye
response-starttls = response-oknobye
sieve-name = string
;; MUST NOT contain NUL, CR or LF
string = quoted / literal
5. Security Considerations
The AUTHENTICATE command uses SASL [SASL] to provide authentication
and authorization services.
Integrity and privacy services can be provided by [SASL] and/or
[TLS]. When a SASL mechanism is used the security considerations for
that mechanism apply.
This protocol's transactions are susceptible to passive observers or
man in the middle attacks which alter the data, unless the optional
encryption and integrity services of the SASL (via the AUTHENTICATE
command) and/or [TLS] (via the STARTTLS command) are enabled, or an
external security mechanism is used for protection. It may be useful
to allow configuration of both clients and servers to refuse to
transfer sensitive information in the absence of strong encryption.
6. IANA Considerations
IANA is requested to reserve TCP port number 2000 for use with
the Manage Sieve protocol described in this document.
IANA is requested to create a new registry for Manage Sieve
capabilities. The registration template for Manage Sieve
capabilities is specified in the next section.
Manage Sieve protocol capabilities MUST be specified in a standards
track or IESG approved experimental RFC.
<<Add a new registry for response codes, as per ABNF comments.>>
<<Reference to SIEVE URL registration.>>
6.1. Manage Sieve Capability Registration Template
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name:
Description:
Relevant publications:
Person & email address to contact for further information:
Author/Change controller:
6.2. Registration of Initial Manage Sieve capabilities.
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name: IMPLEMENTATION
Description: Its value contains name of server
implementation and its version.
Relevant publications: this RFC, section 1.8.
Person & email address to contact for further information:
Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name: SASL
Description: Its value contains a space separated
list of SASL mechanisms supported by server.
Relevant publications: this RFC, sections 1.8 and 2.1.
Person & email address to contact for further information:
Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name: SIEVE
Description: Its value contains a space separated
list of supported SIEVE extensions
Relevant publications: this RFC, section 1.8.
<<Also [SIEVE]>>
Person & email address to contact for further information:
Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name: STARTTLS
Description: This capability is returned if server
supports TLS (STARTTLS command).
Relevant publications: this RFC, sections 1.8 and 2.2.
Person & email address to contact for further information:
Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
To: iana@iana.org
Subject: Manage Sieve Capability Registration
Please register the following Manage Sieve Capability:
Capability name: NOTIFY
Description: This capability is returned if server
supports 'enotify' Sieve extension.
Relevant publications: this RFC, section 1.8.
Person & email address to contact for further information:
Alexey Melnikov <alexey.melnikov@isode.com>
Author/Change controller: IESG.
7. References
7.1. Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[ACAP] Newman, Myers, "ACAP -- Application Configuration Access
Protocol", RFC 2244, Innosoft, Netscape, November 1997.
[SASL] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006.
[SASLprep] Zeilega, K., "SASLprep: Stringprep profile for User Names
and Passwords", RFC 4013, February 2005.
[StringPrep] Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("stringprep")", RFC 3454, December 2002.
[SASL-ANON] K. Zeilenga (Ed.), "Anonymous Simple Authentication and
Security Layer (SASL) Mechanism", RFC 4505, June 2006.
[SIEVE] Guenther, P. and Showalter, T., "Sieve: An Email Filtering
Language", work in Progress, draft-ietf-sieve-3028bis-XX.txt
[TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[URI-GEN] Berners-Lee, T., Fielding, R. and L. Masinter,
"Uniform Resource Identifier (URI): Generic Syntax", RFC 3986,
January 2005.
[BASE64] - Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[NOTIFY] Melnikov, A. (Ed.), Leiba, B. (Ed.), Segmuller, W. and
T. Martin, "Sieve Extension: Notifications", work in progress,
draft-ietf-sieve-notify-XX.txt.
7.2. Informative References
[IMAP4rev1] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 3501, March 2003.
[PLAIN] K. Zeilenga, "The PLAIN Simple Authentication and Security
Layer (SASL) Mechanism", RFC 4616, August 2006.
[DIGEST-MD5] Melnikov, A. (Ed.), "Using Digest Authentication as
a SASL Mechanism", work in progress,
draft-ietf-sasl-rfc2831bis-XX.txt.
8. Author's Address
Tim Martin
BeThereBeSquare Inc.
672 Haight st.
San Francisco, CA 94117
Phone: (510) 260-4175
EMail: timmartin@alumni.cmu.edu
Alexey Melnikov
Isode Ltd.
5 Castle Business Village
36 Station Road
Hampton, Middlesex, TW12 2BX, GB
Email: alexey.melnikov@isode.com
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18. Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
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This document and the information contained herein are provided on
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Appendix A. Acknowledgments
Thanks to Simon Josefsson, Larry Greenfield, Allen Johnson, Chris
Newman, Lyndon Nerenberg, Tim Showalter, Sarah Robeson, Walter
Wong, Barry Leiba, Arnt Gulbrandsen, Stephan Bosch for help with
this document.