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 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Distribution of this memo is unlimited. 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. <> 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. <> 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. <> 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 <> 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. <> 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. <> 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 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" 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 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 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 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. <> Interoperability considerations: None. Security considerations: <>. Contact: Alexey Melnikov Author/Change controller: IESG. References: This document and <> [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. <> 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 <> 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 <> 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. <> <> 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 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 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. <> Person & email address to contact for further information: Alexey Melnikov 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 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 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 Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. 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 retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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.